Discoidin Domain Receptors: Novel Targets in Breast Cancer Bone Metastasis

DTIC Science & Technology

2017-02-01

of invasive BrCa cases with different molecular subtypes, and found a significant inverse association between cytoplasmic DDR1 localization and... inverse association between DDR1 cytoplasmic expression and PR expression in the BrCa tissues analyzed. Specific Aim 2, Task 1 and 2: We defined

Faulting and erosion in the Argentine Precordillera during changes in subduction regime: Reconciling bedrock cooling and detrital records

NASA Astrophysics Data System (ADS)

Fosdick, Julie C.; Carrapa, Barbara; Ortíz, Gustavo

2015-12-01

The Argentine Precordillera is an archetypal retroarc fold-and-thrust belt that records tectonics associated with changing subduction regimes. The interactions between exhumation and faulting in the Precordillera were investigated using apatite and zircon (U-Th-Sm)/He and apatite fission track thermochronometry from the Precordillera and adjacent geologic domains. Inverse modeling of thermal histories constrains eastward in-sequence rock cooling associated with deformation and erosion from 18 to 2 Ma across the Central Precordillera tracking thrusting during this time. The youngest AHe ages (5-2 Ma) and highest erosion rates are located in the eastern and western extremities of the Precordillera and indicate that recent denudation is concentrated at its structural boundaries. Moreover, synchronous rapid Pliocene cooling of the Frontal Cordillera, Eastern Precordillera, and Sierra del Valle Fértil was coeval with initiation of basement-involved faulting in the foreland. Detrital zircon U-Pb geochronology from the ca. 16-8.1 Ma Bermejo foreland basin strata suggests fluvial connectivity westward beyond the Frontal Cordillera to the Main Cordillera and Coast Range followed by an important shift in sediment provenance at ca. 10 Ma. At this time, we suggest that a substantial decrease in Permo-Triassic igneous sources in the Frontal Cordillera and concurrent increase in recycled zircons signatures of Paleozoic strata are best explained by uplift and erosion of the Precordillera during widening of the thrust-belt. Bedrock thermochronology and modeling indicate a 2-6 Myr lag time between faulting-related cooling in the hinterland and the detrital record of deformation in the foreland basin, suggesting that for tectonically active semi-arid settings, bedrock cooling may be more sensitive to onset of faulting. We suggest that high erosion rates in the Frontal Cordillera and Eastern Precordillera are associated with increased interplate coupling during shallowing of the subducting Nazca plate that may concentrate stress along weak structural boundaries of the Precordillera.

Ca isotopes reveal weak control of tectonic uplift on long-term climate change

NASA Astrophysics Data System (ADS)

Moore, J.; Jacobson, A. D.; Holmden, C. E.; Craw, D.

2010-12-01

Ca-Mg silicate weathering consumes atmospheric CO2 over geological timescales (≥106 yr) whereas carbonate weathering has no effect. High Ca fluxes from active orogens have been used to argue that mountain uplift is a disproportionately large CO2 sink. To test this hypothesis, it is essential to determine proportions of Ca from silicate versus carbonate weathering. High precision measurement of Ca isotopes (δ44/40Ca) provides a novel method to directly quantify Ca sources. To this end, we examined δ44/40Ca in rivers draining the Southern Alps of New Zealand. The Southern Alps have large tectonic and climatic gradients but nearly constant bedrock chemistry. West of the main topographic divide, uplift and precipitation rates are high, and steep, fast-flowing rivers drain schist. East of the divide, uplift and precipitation rates are low, and low-gradient, braided rivers drain either schist or greywacke. Both schist and greywacke contain up to 3% hydrothermal and metamorphic calcite. Glaciers feed several schist and greywacke catchments. Examined as δ44/40Ca versus Sr/Ca, values measured for carbonate and silicate end-members define two-component mixing envelopes. Rivers west of the divide plot within the envelope, ruling out isotopic fractionation as a factor for these streams. Several rivers east of the divide are 40Ca enriched relative to the envelope. In-situ fractionation of stream water Ca cannot explain this pattern because fractionation is expected to preferentially remove 40Ca. We measured δ42/44Ca ratios to test if chemical weathering preferentially releases 40Ca. When examined as δ40/44Ca versus δ42/44Ca, the data only display mass-dependent isotope effects. Ca in grass and the exchangeable pool of shallow soils is enriched in 40Ca relative to waters and bedrock. This Ca defines a third mixing end-member that contributes 15-30% of the Ca in rivers east of the divide. Evidence of the plant-fractionated signal likely reflects water residence times, which are longer on the eastern side of the main divide. After correcting for this input, we apportion Ca in all rivers to silicate versus carbonate weathering using a two-component mixing equation. For non-glaciated streams, the δ44/40Ca method and a conventional Ca/Na method agree within 2%. Silicate weathering contributes less Ca west of the main divide where uplift rates are highest. For actively glaciated catchments, the δ44/40Ca method attributes 26% more Ca to silicate weathering than the Ca/Na method. We ascribe this difference to non-stoichiometric leaching of Ca from freshly cleaved rock surfaces. This reaction must occur even faster than carbonate weathering, which dominates in adjacent non-glaciated watersheds. Our results support the assertion that mountain uplift does not dramatically elevate long-term atmospheric CO2 consumption rates compared to tectonically stable landscapes. However, δ44/40Ca reveals that glaciation, which is genetically linked to mountain uplift, yields moderately higher CO2 consumption rates than previously realized. Additionally, our study highlights how biological processes can influence the terrestrial Ca cycle.

Making the case for the Picuris orogeny: Evidence for a 1500 to 1400 Ma orogenic event in the southwestern United States

USGS Publications Warehouse

Daniel, Christopher G.; Jones, James V.; Andronicos, Christopher L.; Gray, Mary Beth; Abbott, Lon D.; Hancock, Gregory S.

2013-01-01

The early Mesoproterozoic (ca. 1400 Ma) is an enigmatic time in the tectonic evolution of southern Laurentia. Circa 1400 Ma granites within Laurentia and multiple other continents have distinctive geochemistry consistent with crustal extension or mantle upwelling. In the southwestern United States, these granites are commonly foliated and are often spatially associated with km-scale ductile shear zones. Deformation is attributed to intracontinental tectonism driven by active convergence along the distal southern margin of Laurentia. The recent discovery of deformed and metamorphosed, ca. 1450 Ma sedimentary rocks in northern New Mexico has strengthened the case for regional deformation and orogenesis. However, important questions remain about the tectonic significance of these events and how to reconcile tectonic models with granite petrology at the regional to global scale. This trip focuses on the protolith age of Proterozoic metasedimentary rocks and the kinematics, timing, and tectonic significance of deformation, magmatism, and metamorphism for the Mesoproterozoic across different crustal levels in the southern Rocky Mountains to highlight the ongoing questions and controversies regarding the Mesoproterozoic tectonic setting of Laurentia.This field trip will examine some of the diverse and most recently discovered evidence for ca. 1400 Ma orogenesis in the southern Rocky Mountains. We hope this trip will promote new interest and discussion about the Mesoproterozoic tectonic evolution of Laurentia. We will visit multiple outcrops in the Wet Mountains of southern Colorado and the Picuris Mountains of northern New Mexico. Stops in the Wet Mountains are arranged from north to south to examine contrasting styles of ca. 1400 Ma deformation with increasing paleodepth across the tilted Proterozoic crustal section. In the Picuris Mountains, we focus on detrital zircon geochronology and revisions to the lithostratigraphy of Paleoproterozoic and recently documented Mesoproterozoic metasedimentary rocks, the nature of regional metamorphism, and the style of deformation, ca. 1450–1400 Ma.

Albari granodiorite - a typical calcalkaline diapir of volcanic arc stage from the Arabian Shield

NASA Astrophysics Data System (ADS)

Radain, Abdulaziz A.

Granodiorite rocks of the Arabian Shield are generally considered to be collision-related granitoids. However, there are some granodiorites that were formed during the volcanic arc stage. Major and trace elements studies are carried out on Albari diapiric granodiorite to reveal its tectonic environment. This intrusive rock type is common in the Taif arc province (Mahd adh Dhahab quadrangle) of the Asir microplate near the border of the southeast dipping subduction zone that ended up with arc-arc collision (Asir-Hijaz microplates) along the now known Bir Umq suture zone. The granodiorite exhibits a calcalkaline trend on ternary AFM and K 2ONa 2OCaO diagrams. Tectonic discrimination diagrams using multicationic parameters (R1 = 4Sill(Na+K)2(Fe+Ti); R2 = 6Ca+2Mg+Al), SiO 2-trace elements (Nb, Y, Rb), and Y versus Nb and Rb versus (Y+Nb) indicate a destructive active plate margin or volcanic arc stage tectonic environment. Albari calcalkaline granodiorite might have been derived directly from partial melting of subducted oceanic crust or overlying mantle contaminated with variable amounts of intermediate (quartz diorite, diorite, tonalite, trondhjemite) early and late volcanic arc-related plutonic country rocks.

Spatial variation of present-day stress field and tectonic regime in Tunisia and surroundings from formal inversion of focal mechanisms: Geodynamic implications for central Mediterranean

NASA Astrophysics Data System (ADS)

Soumaya, Abdelkader; Ben Ayed, Noureddine; Delvaux, Damien; Ghanmi, Mohamed

2015-06-01

We compiled 123 focal mechanisms from various sources for Tunisia and adjacent regions up to Sicily, to image the current stress field in the Maghrebides chain (from Tunisia to Sicily) and its foreland. Stress inversion of all the available data provides a first-order stress field with a N150°E horizontal compression (SHmax) and a transpressional tectonic regime, but the obtained stress tensor poorly fit to the data set. We separated them into regional subsets (boxes) in function of their geographical proximity, kinematic regime, homogeneity of kinematic orientations, and tectonic setting. Their respective inversion evidences second- and third-order spatial variations in tectonic regime and horizontal stress directions. The stress field gradually changes from compression in the Maghrebides thrust belt to transpression and strike slip in the Atlassic and Pelagian foreland, respectively, where preexisting NW-SE to E-W deep faults system are reactivated. This spatial variation of the sismotectonic stress field and tectonic regime is consistent with the neotectonic stress field determined by others from fault slip data. The major Slab Transfer Edge Propagator faults (i.e., North-South Axis-Hammamet relay and Malte Escarpment), which laterally delimit the subducting slabs, play an active role in second- and third-order lateral variations of the tectonic regime and stress field orientations over the Tunisian/Sicilian domain. The past and current tectonic deformations and kinematics of the central Mediterranean are subordinately guided by the plate convergence (i.e., Africa-Eurasia), controlled or influenced by lateral slab migration/segmentation and by deep dynamics such as lithosphere-mantle interaction.

Sedimentary manganese metallogenesis in response to the evolution of the Earth system

NASA Astrophysics Data System (ADS)

Roy, Supriya

2006-08-01

The concentration of manganese in solution and its precipitation in inorganic systems are primarily redox-controlled, guided by several Earth processes most of which were tectonically induced. The Early Archean atmosphere-hydrosphere system was extremely O 2-deficient. Thus, the very high mantle heat flux producing superplumes, severe outgassing and high-temperature hydrothermal activity introduced substantial Mn 2+ in anoxic oceans but prevented its precipitation. During the Late Archean, centered at ca. 2.75 Ga, the introduction of Photosystem II and decrease of the oxygen sinks led to a limited buildup of surface O 2-content locally, initiating modest deposition of manganese in shallow basin-margin oxygenated niches (e.g., deposits in India and Brazil). Rapid burial of organic matter, decline of reduced gases from a progressively oxygenated mantle and a net increase in photosynthetic oxygen marked the Archean-Proterozoic transition. Concurrently, a massive drawdown of atmospheric CO 2 owing to increased weathering rates on the tectonically expanded freeboard of the assembled supercontinents caused Paleoproterozoic glaciations (2.45-2.22 Ga). The spectacular sedimentary manganese deposits (at ca. 2.4 Ga) of Transvaal Supergroup, South Africa, were formed by oxidation of hydrothermally derived Mn 2+ transferred from a stratified ocean to the continental shelf by transgression. Episodes of increased burial rate of organic matter during ca. 2.4 and 2.06 Ga are correlatable to ocean stratification and further rise of oxygen in the atmosphere. Black shale-hosted Mn carbonate deposits in the Birimian sequence (ca. 2.3-2.0 Ga), West Africa, its equivalents in South America and those in the Francevillian sequence (ca. 2.2-2.1 Ga), Gabon are correlatable to this period. Tectonically forced doming-up, attenuation and substantial increase in freeboard areas prompted increased silicate weathering and atmospheric CO 2 drawdown causing glaciation on the Neoproterozoic Rodinia supercontinent. Tectonic rifting and mantle outgassing led to deglaciation. Dissolved Mn 2+ and Fe 2+ concentrated earlier in highly saline stagnant seawater below the ice cover were exported to shallow shelves by transgression during deglaciation. During the Sturtian glacial-interglacial event (ca. 750-700 Ma), interstratified Mn oxide and BIF deposits of Damara sequence, Namibia, was formed. The Varangian (≡ Marinoan; ca. 600 Ma) cryogenic event produced Mn oxide and BIF deposits at Urucum, Jacadigo Group, Brazil. The Datangpo interglacial sequence, South China (Liantuo-Nantuo ≡ Varangian event) contains black shale-hosted Mn carbonate deposits. The Early Paleozoic witnessed several glacioeustatic sea level changes producing small Mn carbonate deposits of Tiantaishan (Early Cambrian) and Taojiang (Mid-Ordovician) in black shale sequences, China, and the major Mn oxide-carbonate deposits of Karadzhal-type, Central Kazakhstan (Late Devonian). The Mesozoic period of intense plate movements and volcanism produced greenhouse climate and stratified oceans. During the Early Jurassic OAE, organic-rich sediments host many Mn carbonate deposits in Europe (e.g., Úrkút, Hungary) in black shale sequences. The Late Jurassic giant Mn Carbonate deposit at Molango, Mexico, was also genetically related to sea level change. Mn carbonates were always derived from Mn oxyhydroxides during early diagenesis. Large Mn oxide deposits of Cretaceous age at Groote Eylandt, Australia and Imini-Tasdremt, Morocco, were also formed during transgression-regression in greenhouse climate. The Early Oligocene giant Mn oxide-carbonate deposit of Chiatura (Georgia) and Nikopol (Ukraine) were developed in a similar situation. Thereafter, manganese sedimentation was entirely shifted to the deep seafloor and since ca. 15 Ma B.P. was climatically controlled (glaciation-deglaciation) assisted by oxygenated polar bottom currents (AABW, NADW). The changes in climate and the sea level were mainly tectonically forced.

Analytically based forward and inverse models of fluvial landscape evolution during temporally continuous climatic and tectonic variations

NASA Astrophysics Data System (ADS)

Goren, Liran; Petit, Carole

2017-04-01

Fluvial channels respond to changing tectonic and climatic conditions by adjusting their patterns of erosion and relief. It is therefore expected that by examining these patterns, we can infer the tectonic and climatic conditions that shaped the channels. However, the potential interference between climatic and tectonic signals complicates this inference. Within the framework of the stream power model that describes incision rate of mountainous bedrock rivers, climate variability has two effects: it influences the erosive power of the river, causing local slope change, and it changes the fluvial response time that controls the rate at which tectonically and climatically induced slope breaks are communicated upstream. Because of this dual role, the fluvial response time during continuous climate change has so far been elusive, which hinders our understanding of environmental signal propagation and preservation in the fluvial topography. An analytic solution of the stream power model during general tectonic and climatic histories gives rise to a new definition of the fluvial response time. The analytic solution offers accurate predictions for landscape evolution that are hard to achieve with classical numerical schemes and thus can be used to validate and evaluate the accuracy of numerical landscape evolution models. The analytic solution together with the new definition of the fluvial response time allow inferring either the tectonic history or the climatic history from river long profiles by using simple linear inversion schemes. Analytic study of landscape evolution during periodic climate change reveals that high frequency (10-100 kyr) climatic oscillations with respect to the response time, such as Milankovitch cycles, are not expected to leave significant fingerprints in the upstream reaches of fluvial channels. Linear inversion schemes are applied to the Tinee river tributaries in the southern French Alps, where tributary long profiles are used to recover the incision rate history of the Tinee main trunk. Inversion results show periodic, high incision rate pulses, which are correlated with interglacial episodes. Similar incision rate histories are recovered for the past 100 kyr when assuming constant climatic conditions or periodic climatic oscillations, in agreement with theoretical predictions.

New 40Ar-39Ar dating of Lower Cretaceous basalts at the southern front of the Central High Atlas, Morocco: insights on late Mesozoic tectonics, sedimentation and magmatism

NASA Astrophysics Data System (ADS)

Moratti, G.; Benvenuti, M.; Santo, A. P.; Laurenzi, M. A.; Braschi, E.; Tommasini, S.

2018-04-01

This study is based upon a stratigraphic and structural revision of a Middle Jurassic-Upper Cretaceous mostly continental succession exposed between Boumalne Dades and Tinghir (Southern Morocco), and aims at reconstructing the relation among sedimentary, tectonic and magmatic processes that affected a portion of the Central High Atlas domains. Basalts interbedded in the continental deposits have been sampled in the two studied sites for petrographic, geochemical and radiogenic isotope analyses. The results of this study provide: (1) a robust support to the local stratigraphic revision and to a regional lithostratigraphic correlation based on new 40Ar-39Ar ages (ca. 120 Ma) of the intervening basalts; (2) clues for reconstructing the relation between magma emplacement in a structural setting characterized by syn-depositional crustal shortening pre-dating the convergent tectonic inversion of the Atlasic rifted basins; (3) a new and intriguing scenario indicating that the Middle Jurassic-Lower Cretaceous basalts of the Central High Atlas could represent the first signal of the present-day Canary Islands mantle plume impinging, flattening, and delaminating the base of the Moroccan continental lithosphere since the Jurassic, and successively dragged passively by the Africa plate motion to NE. The tectono-sedimentary and magmatic events discussed in this paper are preliminarily extended from their local scale into a peculiar geodynamic setting of a continental plate margin flanked by the opening and spreading Central Atlantic and NW Tethys oceans. It is suggested that during the late Mesozoic this setting created an unprecedented condition of intraplate stress for concurrent crustal shortening, related mountain uplift, and thinning of continental lithosphere.

Realizing 2D magnetotelluric inversion in the case of divergent geoelectric strike directions in the crust and mantle - Case study using synthetic models and real data from the Tajo Basin (Spain)

NASA Astrophysics Data System (ADS)

Schmoldt, J.; Jones, A. G.; Muller, M. R.; Kiyan, D.; Hogg, C.; Rosell, O.

2010-12-01

Two-dimensional (2D) inversions of magnetotelluric (MT) data are presently far more commonly used than three-dimensional (3D) inversions as they still significantly outperform 3D inversions in terms of speed, thus allowing for much better resolution of the subsurface through a larger feasible number of grid cells. The suitability of 2D inversion needs thereby to be tested for cases where the electric resistivity structure of the subsurface is potentially 3D to some extent. One particular case of a 3D subsurface structure consists of lateral interfaces with varying orientations at crustal and mantle depths. Such a case might emerge, for instance, where crustal faulting, originating from present day tectonics, is situated above a mantle where structures are dominated by earlier or current plate tectonic processes. Those plate tectonic processes could comprise continental collision from an oblique direction, or lattice preferred orientation in the lithosphere-asthenosphere transition zone due to an oblique relative motion between lithosphere and asthenosphere. Whereas recovery of crustal structures can usually be achieved in a straightforward manner by confining the modelled frequency range to the crustal depths, deriving mantle structures is more challenging. Different approaches for this case have been investigated here using synthetic model studies as well as inversion of a real MT dataset collected in southern Spain as part of the PICASSO fieldwork campaign. The PICASSO project intends to enhance knowledge about the geological setting of the Alboran Domain beneath the western Mediterranean Sea and its surrounding regions, and through that knowledge to understand processes related to continent-continent collision. The Iberian Peninsula is the focus of the first phase of DIAS’s PICASSO efforts, and comprised a magnetotelluric profile crossing the Tajo Basin and Betics Cordillera. Analyses of MT responses and seismic tomography data indicate varying geologic strike direction with depth and along the profile. Geoelectric strike direction in the Tajo Basin crust is approximately NW-SE, coinciding with the direction of the Iberian Range and Neogene faults, whereas at mantle depths a dominant NNE-SSW direction is determined; the Betics region on the contrary exhibits a highly 3D structure originating from its complex tectonic orogeny. This circumstance motivated separate inversions for crustal and mantle structures of the Tajo Basin, as well as for the Betics region. Inversion results of the Tajo Basin subsurface indicate a relatively conducting upper crust underlain by more resistive structures in the lower crust and mantle. The most noticeable features of the models are the apparent upward extension of an electrical resistive lower crustal layer beneath the centre of the basin and the presence of a resistive mantle region that coincides with an area of low seismic velocity. The later indicates an unusual geological situation since typical causes for decreased seismic velocity, e.g. higher temperature, fluids, and less depleted rock chemistry, are commonly thought to decrease electric resistivity.

Determination of Adsorption Equations for Chloro Derivatives of Aniline on Halloysite Adsorbents Using Inverse Liquid Chromatography.

PubMed

Słomkiewicz, Piotr M; Szczepanik, Beata; Garnuszek, Magdalena; Rogala, Paweł; Witkiewicz, Zygfryd

2017-11-01

Chloro derivatives of aniline are commonly used in the production of dyes, pharmaceuticals, and agricultural agents. They are toxic compounds with a large accumulation ability and low natural biodegradability. Halloysite is known as an efficient adsorbent of toxic compounds, such as phenols or herbicides, from wastewater. Inverse LC was applied to measure the adsorption of aniline and 2-chloroaniline (2-CA), 3-chloroaniline (3-CA), and 4-chloroaniline (4-CA) on halloysite adsorbents. A peak division (PD) method was used to determine a Langmuir equation in accordance with the adsorption measurement results. The values of adsorption equilibrium constants and enthalpy were determined and compared by breakthrough curve and PD methods. The physical sense of the calculated adsorption enthalpy values was checked by applying Boudart's entropy criteria. Of note, adsorption enthalpy values for halloysite adsorbents decreased in the following order: aniline > 4-CA > 2-CA > 3-CA.

Basin analysis in the Southern Tethyan margin: Facies sequences, stratal pattern and subsidence history highlight extension-to-inversion processes in the Cretaceous Panormide carbonate platform (NW Sicily)

NASA Astrophysics Data System (ADS)

Basilone, Luca; Sulli, Attilio

2018-01-01

In the Mediterranean, the South-Tethys paleomargin experienced polyphased tectonic episodes and paleoenvironmental perturbations during Mesozoic time. The Cretaceous shallow-water carbonate successions of the Panormide platform, outcropping in the northern edge of the Palermo Mountains (NW Sicily), were studied by integrating facies and stratal pattern with backstripping analysis to recognize the tectonics vs. carbonate sedimentation interaction. The features of the Requienid limestone, including geometric configuration, facies sequence, lithological changes and significance of the top-unconformity, highlight that at the end of the Lower Cretaceous the carbonate platform was tectonically dismembered in various rotating fault-blocks. The variable trends of the subsidence curves testify to different responses, both uplift and downthrow, of various platform-blocks impacted by extensional tectonics. Physical stratigraphic and facies analysis of the Rudistid limestone highlight that during the Upper Cretaceous the previously carbonate platform faulted-blocks were subjected to vertical movements in the direction opposite to the displacement produced by the extensional tectonics, indicating a positive tectonic inversion. Comparisons with other sectors of the Southern Tethyan and Adria paleomargins indicate that during the Cretaceous these areas underwent the same extensional and compressional stages occurring in the Panormide carbonate platform, suggesting a regional scale significance, in time and kinematics, for these tectonic events.

S-type granite from the Gongpoquan arc in the Beishan Orogenic Collage, southern Altaids: Implications for the tectonic transition

NASA Astrophysics Data System (ADS)

Wang, Xinyu; Yuan, Chao; Zhang, Yunying; Long, Xiaoping; Sun, Min; Wang, Lixing; Soldner, Jeremie; Lin, Zhengfan

2018-03-01

Voluminous Paleozoic intrusions occur in the Beishan Orogenic Collage (BOC) and their genesis and tectonic background are important to reconstruct the accretion-collision processes in the southernmost Altaids. Paleozoic is an important period for arc development in the BOC, where the Gongpoquan and Huaniushan arcs are located. There are two pulses of magmatism in the Huaniushan and Gongpoquan arcs, i.e., the ca. 470-423 Ma I-type and ca. 424-395 Ma S- and A-type granitoids. In this study, we focus on two peraluminous granitic plutons in the Gongpoquan arc, i.e., the Baitoushan muscovite granite and Haergen two-mica granite, aiming at unraveling their petrogenesis and tectonic background. Zircon LA-ICP-MS U-Pb dating yields emplacement ages of ca. 409-395 Ma and ca. 409 Ma for the Baitoushan and Haergen plutons, respectively. Both the granitic plutons are strongly peraluminous with A/CNK ratios of 1.10-1.20, indicative of S-type affinities. The rocks are characterized by high SiO2 and K2O contents with high CaO/Na2O ratios. Moreover, the rocks possess low MgO contents, Rb/Sr and Rb/Ba ratios, together with their relatively high initial 87Sr/86Sr ratios (0.7139-0.7152) and less radiogenic εNd(t) values (-3.15 to -5.17), implying a clay-poor and plagioclase-rich crustal source. Compared with earlier pulse of arc-related magmatism (ca. 470-423 Ma), the latter pulse of magmatism (ca. 424-395 Ma) consists mainly of "normal granite" characterized by higher SiO2 (>66%) and K2O contents, weaker fractionated REE patterns and lower δEu values, and gabbroic to dioritic intrusions are only sporadic. Moreover, the granitoids of the latter pulse show variable but more crust-like Sr-Nd isotopic compositions ((87Sr/86Sr)0 = 0.7038-0.7327; εNd(t) = -6.70 to +0.33) than the earlier ones ((87Sr/86Sr)0 = 0.7024-0.7080; εNd(t) = -2.56 to +8.86), indicating that the Early Devonian (ca. 424-395 Ma) experienced extensive crustal melting with minor involvement of mantle materials. Considering Early Devonian geological evidence, the transition from I- to S- and A-type magmatism probably reflects the Early Devonian amalgamation between the Gongpoquan and Huaniushan arcs, which caused not only regional unconformity and strong deformation-metamorphism, but also extensive melting of the accreted crustal materials in the BOC.

Two contrasting late Paleozoic magmatic episodes in the northwestern Chinese Tianshan Belt, NW China: Implication for tectonic transition from plate convergence to intra-plate adjustment during accretionary orogenesis

NASA Astrophysics Data System (ADS)

Wang, Xiangsong; Cai, Keda; Sun, Min; Xiao, Wenjiao; Xia, Xiaoping; Wan, Bo; Bao, Zihe; Wang, Yannan

2018-03-01

Late Carboniferous to Early Permian is a critical period for the final amalgamation of the Central Asian Orogenic Belt (CAOB). However, as most of the accreted terranes of the CAOB are unclear in tectonic nature and origin, the timing and processes of their mutual amalgamation have been poorly constrained. To understand assembly of the West Junggar Terrane with the Yili Block, a suite of the late Paleozoic magmatic rocks, including ignimbrite, rhyolite and granite, in northwestern Chinese Tianshan Belt were studied for their petrogenesis and tectonic implications. Our new results of secondary ion mass spectrometry (SIMS) zircon U-Pb dating reveal two separate magmatic episodes, ca. 300 Ma volcanism (ignimbrite and rhyolite) and ca. 288 Ma plutonsim (biotite granite). Geochemically, for the ca. 300 Ma volcanism, the ignimbrites have low SiO2 (65.8-71.5 wt.%) and Mg# (6-13) values, and exhibit arc affinity with significantly enriched in large ion lithophile elements (LILE) and depleted in high field strength elements (HFSE) such as Nb, Ta and Ti. The whole-rock εNd(t) and zircon εHf(t) values range from +6.9 to +7.0 and +9.9 to +14.1 respectively, indicating a juvenile basaltic lower crustal origin. Rhyolites have slightly high SiO2 (72.7-74.0 wt.%) and K2O (3.86-4.53 wt.%) contents, high zircon δ18O (11.67-13.23‰) values, and low whole-rock εNd(t) (+2.9 to +3.8) and zircon εHf(t) (+2.8 to +10.0) values, which may suggest sediment involvements during magma generation. In contrast, for the ca. 288 Ma plutonism, the biotite granites have obviously higher SiO2 (74.7-75.5 wt.%) contents and whole-rock εNd(t) (+7.7 to +8.8), zircon εHf(t) (+9.8 to +12.7), and lower zircon δ18O (5.99-6.84‰) values, than those of the ca. 300 Ma volcanic rocks, which are consistent with signatures of juvenile magma source. According to our estimates of zircon saturation temperatures, together with their contrasting genesis, we attribute the formation of ca. 300 Ma high temperature (815-938 °C) volcanism to oceanic slab break-off during assembly of the West Junggar Terrane with the Yili Block, and relate the generation of ca. 288 Ma low temperature (723-735 °C) plutonism to subsequent strike-slipping of North Tianshan Fault that facilitated introduction of water-fluxes triggering hydrous partial melting of juvenile lower crust. The sequential magmatic episodes in the northwestern Chinese Tianshan Belt may provide a crucial clue to a tectonic transition from plate convergence to intra-plate adjustment during the formation of the Kazakhstan Orocline in the late Paleozoic.

Inversion for the driving forces of plate tectonics

NASA Technical Reports Server (NTRS)

Richardson, R. M.

1983-01-01

Inverse modeling techniques have been applied to the problem of determining the roles of various forces that may drive and resist plate tectonic motions. Separate linear inverse problems have been solved to find the best fitting pole of rotation for finite element grid point velocities and to find the best combination of force models to fit the observed relative plate velocities for the earth's twelve major plates using the generalized inverse operator. Variance-covariance data on plate motion have also been included. Results emphasize the relative importance of ridge push forces in the driving mechanism. Convergent margin forces are smaller by at least a factor of two, and perhaps by as much as a factor of twenty. Slab pull, apparently, is poorly transmitted to the surface plate as a driving force. Drag forces at the base of the plate are smaller than ridge push forces, although the sign of the force remains in question.

Reactivation of the Archean-Proterozoic suture along the southern margin of Laurentia during the Mazatzal orogeny: Petrogenesis and tectonic implications of ca. 1.63 Ga granite in southeastern Wyoming

USGS Publications Warehouse

Jones, Daniel S.; Barnes, Calvin G.; Premo, Wayne R.; Snoke, Arthur W.

2013-01-01

The presence of ca. 1.63 Ga monzogranite (the “white quartz monzonite”) in the southern Sierra Madre, southeastern Wyoming, is anomalous given its distance from the nearest documented plutons of similar age (central Colorado) and the nearest contemporaneous tectonic margin (New Mexico). It is located immediately south of the Cheyenne belt—a ca. 1.75 Ga Archean-Proterozoic tectonic suture. New geochronological, isotopic, and geochemical data suggest that emplacement of the white quartz monzonite occurred between ca. 1645 and 1628 Ma (main pulse ca. 1628 Ma) and that the white quartz monzonite originated primarily by partial melting of the Big Creek Gneiss, a modified arc complex. There is no evidence that mafic magmas were involved. Open folds of the ca. 1750 Ma regional foliation are cut by undeformed white quartz monzonite. On a regional scale, rocks intruded by the white quartz monzonite have experienced higher pressure and temperature conditions and are migmatitic as compared to the surrounding rocks, suggesting a genetic relationship between the white quartz monzonite and tectonic exhumation. We propose that regional shortening imbricated the Big Creek Gneiss, uplifting the now-exposed high-grade rocks of the Big Creek Gneiss (hanging wall of the thrust and wall rock to the white quartz monzonite) and burying correlative rocks, which partially melted to form the white quartz monzonite. This tectonism is attributed to the ca. 1.65 Ga Mazatzal orogeny, as foreland shortening spread progressively into the Yavapai Province. Mazatzal foreland effects have also been described in the Great Lakes region and have been inferred in the Black Hills of South Dakota. We suggest that the crustal-scale rheologic contrast across the Archean-Proterozoic suture, originally developed along the southern margin of Laurentia, and including the Cheyenne belt, facilitated widespread reactivation of that boundary during the Mazatzal orogeny. This finding emphasizes the degree to which crustal heterogeneities can localize subsequent deformation in accretionary orogens, producing significant crustal melting in the distal foreland—a region not typically associated with orogenic magmatism.

Latest Neoproterozoic basin inversion of the Beardmore Group, central Transantarctic Mountains, Antarctica

NASA Astrophysics Data System (ADS)

Goodge, John W.

1997-08-01

Structural and age relationships in Beardmore Group rocks in the central Transantarctic Mountains of Antarctica indicate that they experienced a single deformation in latest Neoproterozoic to early Paleozoic time. New structural data contrast with earlier suggestions that Beardmore rocks record two orogenic deformations, one of the early Paleozoic Ross orogeny and a distinct earlier tectonic event of presumed Neoproterozoic age referred to as the Beardmore orogeny. In the Nimrod Glacier area, Beardmore metasedimentary rocks contain only a single set of geometrically related regional structures associated with the development of upright, large- and small-scale flexural-slip folds. Deformation of Beardmore strata involved west directed contraction of modest regional strain at relatively high crustal levels. Existing ages of detrital zircons from the Cobham and Goldie formations constrain Beardmore Group deposition to be younger than ˜600 Ma. This is significantly younger than previous age estimates and suggests that Beardmore deposition may be closely linked to a latest Neoproterozoic East Antarctic rift margin. The lack of structural evidence for polyphase deformation and the relatively young depositional age for the Beardmore Group thus raises the question of a temporally and/or technically unique Beardmore orogeny. Here I suggest that Beardmore shortening may be related to tectonic inversion of East Antarctic marginal-basin strata because of localized compression during proto-Pacific seafloor spreading. Basin inversion is but one stage in a protracted Ross tectonic cycle of rifting, tectonic inversion, subduction initiation, and development of a mature convergent continental margin during latest Neoproterozoic and early Paleozoic time. The term "Beardmore orogeny" has little meaning as an event of orogenic status, and it should be abandoned. Recognition of this latest Neoproterozoic history reinforces the view that the broader Ross orogeny was not a single event but rather was a long-lived postrifting tectonic process along the East Antarctic margin of Gondwanaland.

Early Mesozoic paleogeography and tectonic evolution of the western United States: Insights from detrital zircon U-Pb geochronology, Blue Mountains Province, northeastern Oregon

USGS Publications Warehouse

LaMaskin, Todd A.; Vervoort, J.D.; Dorsey, R.J.; Wright, J.E.

2011-01-01

This study assesses early Mesozoic provenance linkages and paleogeographic-tectonic models for the western United States based on new petrographic and detrital zircon data from Triassic and Jurassic sandstones of the "Izee" and Olds Ferry terranes of the Blue Mountains Province, northeastern Oregon. Triassic sediments were likely derived from the Baker terrane offshore accretionary subduction complex and are dominated by Late Archean (ca. 2.7-2.5 Ga), Late Paleoproterozoic (ca. 2.2-1.6 Ga), and Paleozoic (ca. 380-255 Ma) detrital zircon grains. These detrital ages suggest that portions of the Baker terrane have a genetic affinity with other Cordilleran accretionary subduction complexes of the western United States, including those in the Northern Sierra and Eastern Klamath terranes. The abundance of Precambrian grains in detritus derived from an offshore complex highlights the importance of sediment reworking. Jurassic sediments are dominated by Mesozoic detrital ages (ca. 230-160 Ma), contain significant amounts of Paleozoic (ca. 290, 380-350, 480-415 Ma), Neoproterozoic (ca. 675-575 Ma), and Mesoproterozoic grains (ca. 1.4-1.0 Ga), and have lesser quantities of Late Paleoproterozoic grains (ca. 2.1-1.7 Ga). Detrital zircon ages in Jurassic sediments closely resemble well-documented age distributions in transcontinental sands of Ouachita-Appalachian provenance that were transported across the southwestern United States and modified by input from cratonal, miogeoclinal, and Cordilleran-arc sources during Triassic and Jurassic time. Jurassic sediments likely were derived from the Cordilleran arc and an orogenic highland in Nevada that yielded recycled sand from uplifted Triassic backarc basin deposits. Our data suggest that numerous Jurassic Cordilleran basins formed close to the Cordilleran margin and support a model for moderate post-Jurassic translation (~400 km) of the Blue Mountains Province. ?? 2011 Geological Society of America.

Fouling Resistant CA/PVA/TiO2 Imprinted Membranes for Selective Recognition and Separation Salicylic Acid from Waste Water

PubMed Central

Yu, Xiaopeng; Mi, Xueyang; He, Zhihui; Meng, Minjia; Li, Hongji; Yan, Yongsheng

2017-01-01

Highly selective cellulose acetate (CA)/poly (vinyl alcohol) (PVA)/titanium dioxide (TiO2) imprinted membranes were synthesized by phase inversion and dip coating technique. The CA blend imprinted membrane was synthesized by phase inversion technique with CA as membrane matrix, polyethyleneimine (PEI) as the functional polymer, and the salicylic acid (SA) as the template molecule. The CA/PVA/TiO2 imprinted membranes were synthesized by dip coating of CA blend imprinted membrane in PVA and different concentration (0.05, 0.1, 0.2, 0.4 wt %) of TiO2 nanoparticles aqueous solution. The SEM analysis showed that the surface morphology of membrane was strongly influenced by the concentration of TiO2 nanoparticles. Compared with CA/PVA-TiO2(0.05, 0.1, 0.2%)-MIM, the CA/PVA-TiO2(0.4%)-MIM possessed higher membrane flux, kinetic equilibrium adsorption amount, binding capacity and better selectivity for SA. It was found that the pseudo-second-order kinetic model was studied to describe the kinetic of CA/PVA-TiO2(0.2%)-MIM judging by multiple regression analysis. Adsorption isotherm analysis indicated that the maximum adsorption capacity for SA were 24.43 mg g−1. Moreover, the selectivity coefficients of CA/PVA-TiO2 (0.2%)-MIM for SA relative to p-hydroxybenzoic acid (p-HB) and methyl salicylate (MS) were 3.87 and 3.55, respectively. PMID:28184369

Age mapping and dating of monazite on the electron microprobe: Deconvoluting multistage tectonic histories

NASA Astrophysics Data System (ADS)

Williams, Michael L.; Jercinovic, Michael J.; Terry, Michael P.

1999-11-01

High-resolution X-ray mapping and dating of monazite on the electron microprobe are powerful geochronological tools for structural, metamorphic, and tectonic analysis. X-ray maps commonly show complex Th, U, and Pb zoning that reflects monazite growth and overgrowth events. Age maps constructed from the X-ray maps simplify the zoning and highlight age domains. Microprobe dating offers a rapid, in situ method for estimating ages of mapped domains. Application of these techniques has placed new constraints on the tectonic history of three areas. In western Canada, age mapping has revealed multiphase monazite, with older cores and younger rims, included in syntectonic garnet. Microprobe ages show that tectonism occurred ca. 1.9 Ga, 700 m.y. later than mylonitization in the adjacent Snowbird tectonic zone. In New Mexico, age mapping and dating show that the dominant fabric and triple-point metamorphism occurred during a 1.4 Ga reactivation, not during the 1.7 Ga Yavapai-Mazatzal orogeny. In Norway, monazite inclusions in garnet constrain high-pressure metamorphism to ca. 405 Ma, and older cores indicate a previously unrecognized component of ca. 1.0 Ga monazite. In all three areas, microprobe dating and age mapping have provided a critical textural context for geochronologic data and a better understanding of the complex age spectra of these multistage orogenic belts.

Overview of Recent Coastal Tectonic Deformation in the Mexican Subduction Zone

NASA Astrophysics Data System (ADS)

Ramírez-Herrera, M. Teresa; Kostoglodov, Vladimir; Urrutia-Fucugauchi, Jaime

2011-08-01

Holocene and Pleistocene tectonic deformation of the coast in the Mexico subudction margin is recorded by geomorphic and stratigraphic markers. We document the spatial and temporal variability of active deformation on the coastal Mexican subduction margin. Pleistocene uplift rates are estimated using wave-cut platforms at ca. 0.7-0.9 m/ka on the Jalisco block coast, Rivera-North America tectonic plate boundary. We examine reported measurements from marine notches and shoreline angle elevations in conjunction with their radiocarbon ages that indicate surface uplift rates increasing during the Holocene up to ca. 3 ± 0.5 m/ka. In contrast, steady rates of uplift (ca. 0.5-1.0 m/ka) in the Pleistocene and Holocene characterize the Michoacan coastal sector, south of El Gordo graben and north of the Orozco Fracture Zone (OFZ), incorporated within the Cocos-North America plate boundary. Significantly higher rates of surface uplift (ca. 7 m/ka) across the OFZ subduction may reflect the roughness of subducting plate. Absence of preserved marine terraces on the coastal sector across El Gordo graben likely reflects slow uplift or coastal subsidence. Stratigraphic markers and their radiocarbon ages show late Holocene (ca. last 6 ka bp) coastal subsidence on the Guerrero gap sector in agreement with a landscape barren of marine terraces and with archeological evidence of coastal subsidence. Temporal and spatial variability in recent deformation rates on the Mexican Pacific coast may be due to differences in tectonic regimes and to localized processes related to subduction, such as crustal faults, subduction erosion and underplating of subducted materials under the southern Mexico continental margin.

Moment Tensor Inversion of the 1998 Aiquile Earthquake Using Long-period surface waves

NASA Astrophysics Data System (ADS)

Wang, H.

2016-12-01

On 22nd May 1998 at 04:49(GMT), an earthquake of magnitude Mw = 6.6 struck the Aiquile region of Bolivia, causing 105 deaths and significant damage to the nearby towns of Hoyadas and Pampa Grande. This was the largest shallow earthquake (15 km depth) in Bolivia in over 50 years, and was felt as far Sucre, approximately 100 km away. In this report, a centroid moment tensor (CMT) inversion is carried using body waves and surface waves from 1998 Aiquile earthquake with 1-D and 3-D earth models to obtain the source model parameters and moment tensor, which are the values will be subsequently compared against the Global Centroid Moment Tensor Catalog(GCMT). Also, the excitation kernels could be gained and synthetic data can be created with different earth models. The two method for calculating synthetic seismograms are SPECFEM3D Globe which is based on shear wave mantle model S40RTS and crustal model CRUST 2.0, and AxiSEM which is based on PREM 1-D earth Model. Within the report, the theory behind the CMT inversion was explained and the source parameters gained from the inversion can be used to reveal the tectonics of the source of this earthquake, these information could be helpful in assessing seismic hazard and overall tectonic regime of this region. Furthermore, results of synthetic seismograms and the solution of inversion are going to be used to assess two models.

Purinergic signaling triggers endfoot high-amplitude Ca2+ signals and causes inversion of neurovascular coupling after subarachnoid hemorrhage

PubMed Central

Pappas, Anthony C; Koide, Masayo

2016-01-01

Neurovascular coupling supports brain metabolism by matching focal increases in neuronal activity with local arteriolar dilation. Previously, we demonstrated that an emergence of spontaneous endfoot high-amplitude Ca2+ signals (eHACSs) caused a pathologic shift in neurovascular coupling from vasodilation to vasoconstriction in brain slices obtained from subarachnoid hemorrhage model animals. Extracellular purine nucleotides (e.g., ATP) can trigger astrocyte Ca2+ oscillations and may be elevated following subarachnoid hemorrhage. Here, the role of purinergic signaling in subarachnoid hemorrhage-induced eHACSs and inversion of neurovascular coupling was examined by imaging parenchymal arteriolar diameter and astrocyte Ca2+ signals in rat brain slices using two-photon fluorescent and infrared-differential interference contrast microscopy. We report that broad-spectrum inhibition of purinergic (P2) receptors using suramin blocked eHACSs and restored vasodilatory neurovascular coupling after subarachnoid hemorrhage. Importantly, eHACSs were also abolished using a cocktail of inhibitors targeting Gq-coupled P2Y receptors. Further, activation of P2Y receptors in brain slices from un-operated animals triggered high-amplitude Ca2+ events resembling eHACSs and disrupted neurovascular coupling. Neither tetrodotoxin nor bafilomycin A1 affected eHACSs suggesting that purine nucleotides are not released by ongoing neurotransmission and/or vesicular release after subarachnoid hemorrhage. These results indicate that purinergic signaling via P2Y receptors contributes to subarachnoid hemorrhage-induced eHACSs and inversion of neurovascular coupling. PMID:27207166

Purinergic signaling triggers endfoot high-amplitude Ca2+ signals and causes inversion of neurovascular coupling after subarachnoid hemorrhage.

PubMed

Pappas, Anthony C; Koide, Masayo; Wellman, George C

2016-11-01

Neurovascular coupling supports brain metabolism by matching focal increases in neuronal activity with local arteriolar dilation. Previously, we demonstrated that an emergence of spontaneous endfoot high-amplitude Ca 2+ signals (eHACSs) caused a pathologic shift in neurovascular coupling from vasodilation to vasoconstriction in brain slices obtained from subarachnoid hemorrhage model animals. Extracellular purine nucleotides (e.g., ATP) can trigger astrocyte Ca 2+ oscillations and may be elevated following subarachnoid hemorrhage. Here, the role of purinergic signaling in subarachnoid hemorrhage-induced eHACSs and inversion of neurovascular coupling was examined by imaging parenchymal arteriolar diameter and astrocyte Ca 2+ signals in rat brain slices using two-photon fluorescent and infrared-differential interference contrast microscopy. We report that broad-spectrum inhibition of purinergic (P2) receptors using suramin blocked eHACSs and restored vasodilatory neurovascular coupling after subarachnoid hemorrhage. Importantly, eHACSs were also abolished using a cocktail of inhibitors targeting G q -coupled P2Y receptors. Further, activation of P2Y receptors in brain slices from un-operated animals triggered high-amplitude Ca 2+ events resembling eHACSs and disrupted neurovascular coupling. Neither tetrodotoxin nor bafilomycin A1 affected eHACSs suggesting that purine nucleotides are not released by ongoing neurotransmission and/or vesicular release after subarachnoid hemorrhage. These results indicate that purinergic signaling via P2Y receptors contributes to subarachnoid hemorrhage-induced eHACSs and inversion of neurovascular coupling. © The Author(s) 2016.

Tectonic stress pattern in the Chinese Mainland from the inversion of focal mechanism data

NASA Astrophysics Data System (ADS)

Wei, Ju; Weifeng, Sun; Xiaojing, Ma

2017-04-01

The tectonic stress pattern in the Chinese Mainland and kinematic models have been subjected to much debate. In the past several decades, several tectonic stress maps have been figured out; however, they generally suffer a poor time control. In the present study, 421 focal mechanism data up to January 2010 were compiled from the Global/Harvard CMT catalogue, and 396 of them were grouped into 23 distinct regions in function of geographic proximity. Reduced stress tensors were obtained from formal stress inversion for each region. The results indicated that, in the Chinese Mainland, the directions of maximum principal stress were ˜NE-SW-trending in the northeastern region, ˜NEE-SWW-trending in the North China region, ˜N-S-trending in western Xinjiang, southern Tibet and the southern Yunnan region, ˜NNE-SSW-trending in the northern Tibet and Qinghai region, ˜NW-SE-trending in Gansu region, and ˜E-W-trending in the western Sichuan region. The average tectonic stress regime was strike-slip faulting (SS) in the eastern Chinese Mainland and northern Tibet region, normal faulting (NF) in the southern Tibet, western Xinjiang and Yunnan region, and thrust faulting (TF) in most regions of Xinjiang, Qinghai and Gansu. The results of the present study combined with GPS velocities in the Chinese Mainland supported and could provide new insights into previous tectonic models (e.g., the extrusion model). From the perspective of tectonics, the mutual actions among the Eurasian plate, Pacific plate and Indian plate caused the present-day tectonic stress field in the Chinese Mainland.

Tectonic map of Liberia based on geophysical and geological surveys

USGS Publications Warehouse

Behrendt, John Charles; Wotorson, Cletus S.

1972-01-01

Interpretation of the results of aeromagnetic, total-gamma radioactivity, and gravity surveys combined with geologic data for Western Liberia from White and Leo (1969) and other geologic information allows the construction of a tectonic map of Liberia. The map approximately delineates the boundaries between the Liberian (ca. 2700 m.y.) province in the northwestern two-thirds of the country, the Eburnean (ca. 2000 m.y.) province in the south-eastern one-third, and the Pan-African (ca. 550 m.y.) province in the coastal area of the northwestern two-thirds of the country. Rock follation and tectonic structural features trend northeastward in the Liberian province, east-northeastward to north-northeastward in the Eburnean province, and northwestward in the Pan-African age province. Linear residual magnetic anomailes 20-80 km wide and 200-600 gammas in amplitude and following the northeast structural trend typical of the Liberian age province cross the entire country and extend into Sierra Leone and Ivory Coast.

The carbon cycle and biogeochemical dynamics in lake sediments

USGS Publications Warehouse

Dean, W.E.

1999-01-01

The concentrations of organic carbon (OC) and CaCO3 in lake sediments are often inversely related. This relation occurs in surface sediments from different locations in the same lake, surface sediments from different lakes, and with depth in Holocene sediments. Where data on accumulation rates are available, the relation holds for organic carbon and CaCO3 accumulation rates as well. An increase of several percent OC is accompanied by a decrease of several tens of percent CaCO3 indicating that the inverse relation is not due to simple dilution of one component by another. It appears from core data that once the OC concentration in the sediments becomes greater than about 12%, the CO2 produced by decomposition of that OC and production of organic acids lowers the pH of anoxic pore waters enough to dissolve any CaCO3 that reaches the sediment-water interface. In a lake with a seasonally anoxic hypolimnion, processes in the water column also can produce an inverse relation between OC and CaCO3 over time. If productivity of the lake increases, the rain rate of OC from the epilimnion increases. Biogenic removal of CO2 and accompanying increase in pH also may increase the production of CaCO3. However, the decomposition of organic matter in the hypolimnion will decrease the pH of the hypolimnion causing greater dissolution of CaCO3 and therefore a decrease in the rain rate of CaCO3 to the sediment-water interface.

Stress field during early magmatism in the Ali Sabieh Dome, Djibouti, SE Afar rift

NASA Astrophysics Data System (ADS)

Sue, Christian; Le Gall, Bernard; Daoud, Ahmed Mohamed

2014-09-01

The so-called Ali Sabieh range, SE Afar rift, exhibits an atypical antiform structure occurring in the overall extensional tectonic context of the Afar triple junction. We dynamically analyzed the brittle deformation of this specific structural high using four different methods in order to better constrain the tectonic evolution of this key-area in the Afar depression. Paleostress inversions appear highly consistent using the four methods, which a posteriori validates this approach. Computed paleostress fields document two major signals: an early E-W extensional field, and a later transcurrent field, kinematically consistent with the previous one. The Ali Sabieh range may have evolved continuously during Oligo-Miocene times from large-scale extensional to transcurrent tectonism, as the result of probable local stress permutation between σ1 and σ2 stress axes.

Tectonic evolution of the northern African margin in Tunisia from paleostress data and sedimentary record

NASA Astrophysics Data System (ADS)

Bouaziz, Samir; Barrier, Eric; Soussi, Mohamed; Turki, Mohamed M.; Zouari, Hédi

2002-11-01

A reconstruction of the tectonic evolution of the northern African margin in Tunisia since the Late Permian combining paleostress, tectonic stratigraphic and sedimentary approaches allows the characterization of several major periods corresponding to consistent stress patterns. The extension lasting from the Late Permian to the Middle Triassic is contemporaneous of the rifting related to the break up of Pangea. During Liassic times, regional extensional tectonics originated the dislocation of the initial continental platform. In northern Tunisia, the evolution of the Liassic NE-SW rifting led during Dogger times to the North African passive continental margin, whereas in southern Tunisia, a N-S extension, associated with E-W trending subsiding basins, lasted from the Jurassic until the Early Cretaceous. After an Upper Aptian-Early Albian transpressional event, NE-SW to ENE-WSW trending extensions prevailed during Late Cretaceous in relationship with the general tectonic evolution of the northeastern African plate. The inversions started in the Late Maastrichtian-Paleocene in northern Tunisia, probably as a consequence of the Africa-Eurasia convergence. Two major NW-SE trending compressions occurred in the Late Eocene and in the Middle-Late Miocene alternating with extensional periods in the Eocene, Oligocene, Early-Middle Miocene and Pliocene. The latter compressional event led to the complete inversion of the basins of the northwestern African plate, originating the Maghrebide chain. Such a study, supported by a high density of paleostress data and including complementary structural and stratigraphic approaches, provides a reliable way of determining the regional tectonic evolution.

On some basic principles of the wave planetology illustrated by real shapes and tectonic patterns of celestial bodies

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2011-10-01

The physical background. Celestial bodies move in orbits and keep them due to equality of centrifugal and attractio n forces. These forces are oppositely directed. There is a third force -the inert ia-gravity one directed at the right angle to mentioned above and, thus, not interfering with them (Fig. 1). This force is caused by moving all celestial bodies in non -circular keplerian orbits with periodically changing accelerations. A clear illustration of status of this third force is a stretched rope never achieving a straight line because of the not compensated rope weight acting at the right angle to the stretching force s. In the cas e of cosmic bodies this "not compens ated" inertia-gravity force is absorbed in a cosmic body mass making this mass to warp, undulate. This warping in form of standing waves in rotating bodies is decomposed in four interfering direct ions (ortho - and diagonal) (Fig. 2) producing uplifted (+, ++), subsided (-, --) and neutral (0) blocks (Fig. 2). An interfe rence of fundamental waves 1 long 2π R ma kes always pres ent in bodies tectonic dichotomy: an oppos ition of two hemispheres-segments - one uplifted, another subsided (Fig. 2-6). The first overtone of the wave 1 - wave 2 long πR ma kes tectonic sectors superimposed on segments -hemispheres (Fig. 2, 7, 8). Along with the segment -sectoral pattern in cosmic bodies tectonic granulation develops (Fig. 9, 10). The granule sizes are inversely proportional to orbital frequencies [1-3]. The sectoral tectonic blocks are clearly visible also on Venus and icy satellites of Saturn, especially on polar views. Earth and photosphere are remarkable reference points of this fundamental dependence: orbits - tectonic granulation (Fig. 9, 10).

The Bowland Basin, NW England: Base metal mineralisation and its relationship to basin evolution

NASA Astrophysics Data System (ADS)

Gaunt, Jonathan Mark

The Bowland Basin of NW England is a Carboniferous half graben. The Basin was initiated in the Devonian and actively extended during the Carboniferous until the late Westphalian. From the late Westphalian to the early Permian the Bowland Basin underwent inversion in response to Hercynian collision tectonics. Renewed subsidence commenced in the Permian and continued until inversion in the Cenozoic. The sedimentary succession of the Bowland Basin is dominated by Carboniferous strata, but some Permo-Triassic strata are present. The basal sedimentary succession may be comprised of Devonian to early Dinantian syn-rift clastics. The main Dinantian succession is comprised of interbedded limestones, calcareous mudstones and clastic strata. The Dinantian strata include the Waulsortian-facies Clitheroe Limestone and the Limekiln Wood Limestone, both of which host mineralisation. The overlying Namurian is comprised of shales and sandstones. The diagenetic history of the Limekiln Wood Limestone and Waulsortian-facies Clitheroe Limestone in the Cow Ark-Marl Hill Moor district is a function of changes in the burial environment during the Carboniferous. Both exhibit a pre-basin inversion diagenetic sequence that changes with time from shallow to moderate burial depth cements. Late Carbonifeous basin inversion resulted in the formation of tectonic stylolites. Tectonic stylolitisation was postdated by dolomitisation and silicification. Dolomitisation and silicification are suggested to have taken place in the deep burial environment. The base metal mineralisation studied in this work comes from the Cow Ark- Marl Hill Moor district, which is sited on the present basin inversion axis. Mineralisation occurs as four distinct episodes (Period 1, Period 2, Period 3 and Post-Period 3) within a complex multigeneration vein suite. The vein suite, which postdates tectonic stylolitisation and hence end-Carboniferous basin inversion, is comprised of calcite, baroque dolomite, baroque ankerite and siderite. The veins, which are often spatially associated with faults, exhibit a variety of morphologies, and are largely hosted by hydraulic shear fractures. Compositional variations between the different vein carbonates occur with time and the calcites, baroque dolomites, baroque ankerites and siderites are interpreted to have had several different fluid sources. Fluids precipitating siderite, baroque dolomite and baroque ankerite may have been produced by clay mineral transformations and decarboxylation of organic matter within the calcareous strata. The multiple vein calcite generations belong to three MnO:FeO compositional classes, each occupying a specific paragenetic position. The trend from ferroan to manganoan calcite with time may be a consequence of calcite-forming fluids being derived from successively shallower depths within the sedimentary succession, or of increased permeation by meteoric fluids. (Abstract shortened by ProQuest.).

Developing Regionalized Models of Lithospheric Thickness and Velocity Structure Across Eurasia and the Middle East from Jointly Inverting P-Wave and S-Wave Receiver Functions with Rayleigh Wave Group and Phase Velocities

DTIC Science & Technology

2010-09-01

lithospheric velocity structure for a wide variety of tectonic regions throughout Eurasia and the Middle East. We expect the regionalized models will improve...constructed by combining the 1D joint inversion models within each tectonic region and validated through regional waveform modeling. The velocity models thus...important differences in lithospheric structure between the cratonic regions of Eastern Europe and the tectonic regions of Western Europe and the

Easy handling of tectonic data: the programs TectonicVB for Mac and TectonicsFP for Windows™

NASA Astrophysics Data System (ADS)

Ortner, Hugo; Reiter, Franz; Acs, Peter

2002-12-01

TectonicVB for Macintosh and TectonicsFP for Windows TM operating systems are two menu-driven computer programs which allow the shared use of data on these environments. The programs can produce stereographic plots of orientation data (great circles, poles, lineations). Frequently used statistical procedures like calculation of eigenvalues and eigenvectors, calculation of mean vector with concentration parameters and confidence cone can be easily performed. Fault data can be plotted in stereographic projection (Angelier and Hoeppener plots). Sorting of datasets into homogeneous subsets and rotation of tectonic data can be performed in interactive two-diagram windows. The paleostress tensor can be calculated from fault data sets using graphical (calculation of kinematic axes and right dihedra method) or mathematical methods (direct inversion or numerical dynamical analysis). The calculations can be checked in dimensionless Mohr diagrams and fluctuation histograms.

Late-Variscan Tectonic Inheritance and Salt Tectonics Interplay in the Central Lusitanian Basin

NASA Astrophysics Data System (ADS)

Nogueira, Carlos R.; Marques, Fernando O.

2017-04-01

Tectonic inheritance and salt structures can play an important role in the tectono-sedimentary evolution of basins. The Alpine regional stress field in west Iberia had a horizontal maximum compressive stress striking approximately NNW-SSE, related to the Late Miocene inversion event. However, this stress field cannot produce a great deal of the observed and mapped structures in the Lusitanian Basin. Moreover, many observed structures show a trend similar to well-known basement fault systems. The Central Lusitanian basin shows an interesting tectonic structure, the Montejunto structure, generally assigned to this inversion event. Therefore, special attention was paid to: (1) basement control of important observed structures; and (2) diapir tectonics (vertical maximum compressive stress), which can be responsible for significant vertical movements. Based on fieldwork, tectonic analysis and interpretation of geological maps (Portuguese Geological Survey, 1:50000 scale) and geophysical data, our work shows: (1) the Montejunto structure is a composite structure comprising an antiform with a curved hinge and middle Jurassic core, and bounding main faults; (2) the antiform can be divided into three main segments: (i) a northern segment with NNE-SSW trend showing W-dipping bedding bounded at the eastern border by a NNE-SSW striking fault, (ii) a curved central segment, showing the highest topography, with a middle Jurassic core and radial dipping bedding, (iii) a western segment with ENE-WSW trend comprising an antiform with a steeper northern limb and periclinal termination towards WSW, bounded to the south by ENE-WSW reverse faulting, (3) both fold and fault trends at the northern and western segments are parallel to well-known basement faults related to late-Variscan strike-slip systems with NNE-SSW and ENE-WSW trends; (4) given the orientation of Alpine maximum compressive stress, the northern segment border fault should be mostly sinistral strike-slip and the western segment border fault should be a pure thrust; (5) uplift along the northern and central segments may point out to the presence of a salt diapir at depth, aiding vertical movement and local uplift of the structure; (6) geometry of seismic units of the neighboring basins is consistent with halokinesis related to the antiform growth during the Jurassic; (7) sedimentary filling of the neighbouring basins shows relationship to antiform development and growth into a structural high before the Late Miocene Alpine event. These data suggest that: (1) pre-existing basement faults and their reactivation played important role on the development of Montejunto complex tectonic structure; (2) important vertical movements occurred as the result of regional and local (diapir) tectonics; (3) subsidence in neighbouring basins may have promoted maturation, and possible targets with strong potential for hydrocarbon trapping and accumulation may have also developed; (4) diapir tectonics initiated before the Cretaceous; (5) given the topography, and the geometry and inferred kinematics of all segments, it seems that the Montejunto structure formed in a restraining bend controlled by inherited late-Variscan basement faults.

Escape tectonism in the Gulf of Thailand: Paleogene left-lateral pull-apart rifting in the Vietnamese part of the Malay Basin

NASA Astrophysics Data System (ADS)

Fyhn, Michael B. W.; Boldreel, Lars O.; Nielsen, Lars H.

2010-03-01

The Malay Basin represents one of the largest rift basins of SE Asia. Based on a comprehensive 2-D seismic database tied to wells covering mainly Vietnamese acreage, the evolution of the Vietnamese part of the basin is outlined and a new tectonic model is proposed for the development of the basin. The Vietnamese part of the Malay Basin comprises a large and deep Paleogene pull-apart basin formed through Middle or Late Eocene to Oligocene left-lateral strike-slip along NNW-trending fault zones. The Tho Chu Fault Zone constitutes a significant Paleogene left-lateral strike-slip zone most likely associated with SE Asian extrusion tectonism. The fault zone outlines a deep rift that widens to the south and connects with the main Malay Basin. In the central northern part of the basin, a series of intra-basinal left-lateral fracture zones are interconnected by NW to WNW-trending extensional faults and worked to distribute sinistral shearing across the width of the basin. Extensive thermal sagging throughout the Neogene has led to the accommodation of a very thick sedimentary succession. Moderate rifting resumed during the Early Miocene following older structural fabric. The intensity of rifting increases towards the west and was probably related to coeval extension in the western part of the Gulf of Thailand. Neogene extension culminated before the Pliocene, although faults in places remains active. Late Neogene basin inversion has been attributed to c. 70 km of right-lateral movement across major c. N-S-trending faults in the central part of the basin. However, the lack of inversion in Vietnamese territory only seems to merit a few kilometers of dextral inversion.

Deep structure of the Alborz Mountains by joint inversion of P receiver functions and dispersion curves

NASA Astrophysics Data System (ADS)

Rastgoo, Mehdi; Rahimi, Habib; Motaghi, Khalil; Shabanian, Esmaeil; Romanelli, Fabio; Panza, Giuliano F.

2018-04-01

The Alborz Mountains represent a tectonically and seismically active convergent boundary in the Arabia - Eurasia collision zone, in western Asia. The orogenic belt has undergone a long-lasted tectono-magmatic history since the Cretaceous. The relationship between shallow and deep structures in this complex tectonic domain is not straightforward. We present a 2D velocity model constructed by the assemblage of 1D shear wave velocity (Vs) models from 26 seismic stations, mainly distributed along the southern flank of the Alborz Mountains. The shear wave velocity structure has been estimated beneath each station using joint inversion of P-waves receiver functions and Rayleigh wave dispersion curves. A substantiation of the Vs inversion results sits on the modeling of Bouguer gravity anomaly data. Our velocity and density models show low velocity/density anomalies in uppermost mantle of western and central Alborz at a depth range of ∼50-100 km. In deeper parts of the uppermost mantle (depth range of 100-150 km), a high velocity/density anomaly is located beneath most of the Mountain range. The spatial pattern of these low and high velocity/density structures in the upper mantle is interpreted as the result of post collisional delamination of lower part of the western and central Alborz lithosphere.

Lead mobilization during tectonic reactivation of the western Baltic Shield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romer, R.L.; Wright, J.E.

Lead isotope data from sulfide deposits of the western part of the Baltic Shield define mixing lines in the [sup 206]Pb/[sup 204]Pb-[sup 207]Pb/[sup 204]Pb diagram. Lead from two types of sulfide deposits have been investigated: (1) Exhalative and volcanogenic deposits that are syngenetic with their host rocks; and (2) vein deposits. The syngenetic deposits locally show a very wide range of lead isotopic compositions that reflect a variable addition of highly radiogenic lead, while the vein deposits, although they have radiogenic lead isotopic compositions, exhibit only limited isotopic variations. In different provinces of the shield, both types of deposits fallmore » on the same lead mixing array. The slope of the lead mixing lines varies as a function of the age of basement rocks and the age of the tectonic event which produced the lead mobilization and therefore relates the source rock age with the age of lead mobilization. Calculated mixing ages fall into several short time periods that correspond either to orogenic events or to major phases of continental rifting. The orogenic events are the ca 360--430 Ma Caledonian, ca 900--1100 Ma Sveconorwegian, and the ca 1800--1900 Ma Svecofennian orogenic cycles. The rifting events correspond to the formation of the ca 280 Ma Oslo rift and the Ordovician (ca 450 Ma) graben system in the area of the present Gulf of Bothnia. Each mixing age indicates that lead was mobilized, probably as a consequence of mild thermal disturbances, and that the crust was permeable to lead migration. The data show that the geographic distribution of sulfide deposits with highly radiogenic lead isotopic compositions coincides with old graben systems, orogenic belts, and orogenic forelands on the Baltic Shield. The ages of vein deposits and their geographic distribution demonstrate multiple tectonic reactivation of the interior of the Baltic Shield in response to orogenic events at its margin. 68 refs., 6 refs., 4 tabs.« less

FAST INVERSION OF SOLAR Ca II SPECTRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beck, C.; Choudhary, D. P.; Rezaei, R.

We present a fast (<<1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ∼ –3 and increases to valuesmore » of 2.5 and 4 at log τ = –6 in the quiet Sun and the umbra, respectively.« less

Comparing The North-east German Basin With The Polish Basin, Influenced By Major Crustal Fractures

NASA Astrophysics Data System (ADS)

Lamarche, J.; Scheck, M.; Otto, V.; Bayer, U.; Lewerenz, B.

The North-East German Basin (NEGB) and the Polish Basin (PB) are two intraplate sedimentary basins in Central Europe, the development of which was controlled by deep crustal structures: the Elbe Fault System and the Teisseyre-Tornquist Zone, re- spectively. 3D structural models performed separately for each basin led to indepen- dent interpretations showing major similarities, but also significant differences. The outlook of the comparison between the NEGB and the PB is to lead to a joined 3D structural model, which allows reconstructing the synthetic geodynamic evolution of the area. The NEGB and PB are NW-SE-oriented. Both were initiated during Late Carboniferous and Lower Permian, when the post-Variscan rifting affected the com- posite Palaeozoic basement of Central Europe. During Triassic to Cretaceous times, both basins evolved due to thermal subsidence and pulses of tectonic subsidence. At the end of Cretaceous, the basins were tectonically inverted. The sedimentary succes- sions of the NEGB and PB are comparable. Particularly, the Zechstein salt induced comparable sedimentary structures and provided a decoupling level between pre- and post-Zechstein rocks during the Late Cretaceous tectonic inversion in both basins. At the crustal scale, both basins are presently limited to the SW by the NW-SE-oriented Elbe Fault System, that correlates with a positive gravity anomaly. Finally, both basins show a N-S differentiation regarding the detailed subsidence history, the structural set- ting and the salt pattern. In spite of the very similar tectonic evolution of the NEGB and the PB, their large-scale geometry and inversion-related structures are different. The NEGB is asymmetric with a shallow northern slope and a steep bounding fault at the SW margin (Elbe Fault System). In the NEGB, the Late Cretaceous tectonic inversion resulted in asymmetric uplift of the SW' border along the Elbe Fault Sys- tem, and in decreasing deformation in the cover towards North. In contrast, the PB is a symmetric basin, that developed above the Teisseyre-Tornquist Zone. The tectonic inversion resulted in a rather symmetric swell, uplifted along the axis of the former basin. The occurrence and rejuvenation of the deep-seated Teisseyre-Tornquist Zone is held responsible for the symmetry of the PB during its development and later inver- sion, whereas the reactivation of the Elbe Fault Zone induced asymmetric deformation in the Mesozoic cover at the SW margin of the NEGB.

Origin of the Lyme Dome and implications for the timing of multiple Alleghanian deformational and intrusive events in southern Connecticut

USGS Publications Warehouse

Walsh, G.J.; Aleinikoff, J.N.; Wintsch, R.P.

2007-01-01

Geologic mapping, structural analysis, and geochronology in the area of the Lyme dome, southern Connecticut provides constraints on the origin of the rocks in the core of the dome, the absolute timing of the principal deformational and thermal events attributed to Alleghanian orogenesis, and the processes that generated the dome. Detrital zircon geochronology in combination with ages on intrusive rocks brackets the deposition of quartzite in the core of the dome sometime between ca. 925 and 620 Ma. Granite and granodiorite intruded the Neoproteorozic metasedimentary rocks in the core of the dome at ca. 620 to 610 Ma. Four major early Permian events associated with the Alleghanian orogeny affected the rocks in the Lyme dome area. Syn-tectonic migmatization and widespread penetrative deformation (D1, ca. 300 - 290 Ma) included emplacement of alaskite at 290 ?? 4 Ma during regional foliation development and aluminosilicate-orthoclase metamorphic conditions. Rocks of the Avalon terrane may have wedged between Gander cover rocks and Gander basement in the core of the Lyme during D1. Limited structural evidence for diapiric uplift of the Lyme dome indicates that diapirism started late in D1 and was completed by D2 (ca. 290 - 280 Ma) when horizontal WNW contractional stresses dominated over vertical stresses. Second sillimanite metamorphism continued and syn-tectonic D2 granite pegmatite (288 ?? 4 Ma) and the Joshua Rock Granite Gniess (284 ?? 3 Ma) intruded at this time. North-northwest extension during D3 (ca. 280 - 275 Ma) led to granitic pegmatite intrusion along S3 cleavage planes and in extensional zones in boudin necks during hydraulic failure and decompression melting. Intrusion of a Westerly Granite dike at 275 ?? 4 Ma suggests that D3 extension was active, and perhaps concluding, by ca. 275 Ma. Late randomly oriented but gently dipping pegmatite dikes record a final stage of intrusion during D4 (ca. 275 - 260 Ma), and a switch from NNW extension to vertical unloading and exhumation. Monazite and metamorphic zircon rim ages record this event at ca. 259 Ma. The evolution of the Lyme dome involved D1 mylonitization, intrusion, and migmatization during north-directed contraction, limited late D1 diapirism, D2 migmatization during WNW contraction with associated flexural flow and fold interference, D3 NNW horizontal extension and decompression melting, and final D4 vertical extension and rapid exhumation. Late regional uplift, extension, and normal faulting at higher crustal levels may have been caused by diapiric rise of the lower crust, below the structural level of the Lyme dome. The rocks record no evidence of Acadian metamorphism or deformation, suggesting that the Gander zone here was not tectonically juxtaposed with Avalon until the Alleghanian orogeny.

PRE- AND POST-SYNAPTIC EFFECTS OF MANIPULATING SURFACE CHARGE WITH DIVALENT CATIONS AT THE PHOTORECEPTOR SYNAPSE

PubMed Central

CADETTI, L.; THORESON, W. B.; PICCOLINO, M.

2006-01-01

Persistence of horizontal cell (HC) light responses in extracellular solutions containing low Ca2+ plus divalent cations to block Ca2+ currents (ICa) has been attributed to Ca2+-independent neurotransmission. Using a retinal slice preparation to record both ICa and light responses, we demonstrate that persistence of HC responses in low [Ca2+]o can instead be explained by a paradoxical increase of Ca2+ influx into photoreceptor terminals arising from surface charge-mediated shifts in ICa activation. Consistent with this explanation, application of Zn2+ or Ni2+ caused a hyperpolarizing block of HC light responses that was relieved by lowering [Ca2+]o. The same concentrations of Zn2+ and Ni2+ reduced the amplitude of ICa at the rod dark potential and this reduction was relieved by a hyperpolarizing shift in voltage dependence induced by lowering [Ca2+]o. Block of ICa by Mg2+, which has weak surface charge effects, was not relieved by low [Ca2+]o. Recovery of HC responses in low [Ca2+]o was assisted by enhancement of rod light responses. To bypass light stimulation, OFF bipolar cells were stimulated by steps to −40 mV applied to presynaptic rods during simultaneous paired recordings. Consistent with surface charge theory, the post-synaptic current was inhibited by Zn2+ and this inhibition was relieved by lowering [Ca2+]o. Nominally divalent-free media produced inversion of HC light responses even though rod light responses remained hyperpolarizing; HC response inversion can be explained by surface charge-mediated shifts in ICa. In summary, HC light responses modifications induced by low divalent cation solutions can be explained by effects on photoreceptor light responses and membrane surface charge without necessitating Ca2+-independent neurotransmission. Furthermore, these results suggest that surface charge effects accompanying physiological changing divalent cation levels in the synaptic cleft may provide a means for modulating synaptic output from photoreceptors. PMID:15541900

Advanced Multivariate Inversion Techniques for High Resolution 3D Geophysical Modeling

DTIC Science & Technology

2010-09-01

crustal structures. But short periods are difficult to measure, especially in tectonically and geologically complex areas. On the other hand, gravity...East Africa Rift System Knowledge of crustal and upper mantle structure is of importance for understanding East Africa’s geodynamic evolution and for...area with less lateral heterogeneity but great tectonic complexity. To increase the effectiveness of the technique in this region, we explore gravity

Stress states in the Zagros fold-and-thrust belt from passive margin to collisional tectonic setting

NASA Astrophysics Data System (ADS)

Navabpour, Payman; Barrier, Eric

2012-12-01

The present-day Zagros fold-and-thrust belt of SW-Iran corresponds to the former Arabian passive continental margin of the southern Neo-Tethyan basin since the Permian-Triassic rifting, undergoing later collisional deformation in mid-late Cenozoic times. In this paper an overview of brittle tectonics and palaeostress reconstructions of the Zagros fold-and-thrust belt is presented, based on direct stress tensor inversion of fault slip data. The results indicate that, during the Neo-Tethyan oceanic opening, an extensional tectonic regime affectedthe sedimentary cover in Triassic-Jurassic times with an approximately N-S trend of the σ3 axis, oblique to the margin, which was followed by some local changes to a NE-SW trend during Jurassic-Cretaceous times. The stress state significantly changed to thrust setting, with a NE-SW trend of the σ1 axis, and a compressional tectonic regime prevailed during the continental collision and folding of the sedimentary cover in Oligocene-Miocene times. This compression was then followed by a strike-slip stress state with an approximately N-S trend of the σ1 axis, oblique to the belt, during inversion of the inherited extensional basement structures in Pliocene-Recent times. The brittle tectonic reconstructions, therefore, highlighted major changes of the stress state in conjunction with transitions between thin- and thick-skinned structures during different extensional and compressional stages of continental deformation within the oblique divergent and convergent settings, respectively.

Late Cretaceous to Cenozoic deformation and exhumation of the Chilean Frontal Cordillera (28°-29°S), Central Andes

NASA Astrophysics Data System (ADS)

Martínez, Fernando; Parra, Mauricio; Arriagada, César; Mora, Andrés; Bascuñan, Sebastián; Peña, Matías

2017-11-01

The Frontal Cordillera in northern Chile is located over the flat-slab subduction segment of the Central Andes. This tectonic province is characterized by a thick-skinned structural style showing evidence of tectonic inversion and basement-involved compressive structures. Field data, U-Pb geochronological and apatite fission track data were used to unravel partially the tectonic history of the area. Previous U-Pb ages of synorogenic deposits exposed on the flanks of basement-core anticlines indicate that Andean deformation started probably during Late Cretaceous with the tectonic inversion of Triassic and Jurassic half-grabens. New U-Pb ages of the synorogenic Quebrada Seca Formation suggest that this deformation continued during Paleocene (66-60 Ma) with the reverse faulting of pre-rift basement blocks. The analysis of new apatite fission-track data shows that a rapid and coeval cooling related to exhumation of the pre-rift basement blocks occurred during Eocene times. This exhumation event is interpreted for first time in the Chilean Frontal Cordillera and it could have occurred simultaneously with the propagation of basement-involved structures. The age of this exhumation event coincides with the Incaic orogenic phase, which is interpreted as the most important to the Central Andes in terms of shortening, uplift and exhumation.

Activation of TRPV4 channels does not mediate inversion of neurovascular coupling after SAH.

PubMed

Koide, Masayo; Wellman, George C

2015-01-01

Neurovascular coupling (NVC) allows increased blood flow to metabolically active neurons and involves the Ca²⁺ -dependent release of vasodilator influences by astrocyte endfeet that encase parenchymal arterioles. We previously reported inversion of NVC from dilation to constriction in brain slices from subarachnoid hemorrhage (SAH) model rats. Corresponding to NVC inversion, there was a marked increase in the amplitude of spontaneous Ca²⁺ oscillations in astrocyte endfeet. Calcium-permeable transient receptor potential vanilloid (TRPV)-4 channels have been reported in astrocyte endfeet, and activators of these channels enhance Ca²⁺ oscillations in healthy animals. Here, we examined the role of TRPV4 channels in the development of high-amplitude spontaneous Ca²⁺ oscillations in astrocyte endfeet and the inversion of neurovascular coupling after SAH. Treatment of brain slices with the TRPV4 channel antagonist, HC-067047 (10 μM), did not alter the amplitude of spontaneous Ca²⁺ oscillations after SAH. In addition, HC-067047 did not inhibit or change SAH-induced inversion of neurovascular coupling. In summary, TRPV4 channels do not appear to be involved in the inversion of neurovascular coupling after SAH. Further studies examining the impact of SAH on additional Ca²⁺ signaling pathways in astrocytes are likely to reveal valuable insights into new therapeutic strategies to advance SAH treatments.

Ca isotopes, chemical weathering, and geomorphic controls on long-term climate

NASA Astrophysics Data System (ADS)

Moore, J.; Jacobson, A. D.; Holmden, C. E.; Craw, D.

2009-12-01

Calcium isotope geochemistry (δ44Ca) offers a unique opportunity to directly quantify proportions of riverine Ca originating from silicate versus carbonate weathering, which is essential for understanding how geomorphic processes affecting landscape evolution, such as tectonic uplift and glaciation, influence the long-term cycling of atmospheric CO2. We measured the elemental and δ44Ca chemistry of river and rock samples from the New Zealand Southern Alps. In combination with our geochemical data, we used runoff and suspended sediment fluxes to elucidate relationships between chemical weathering, mechanical erosion, and long-term climate. The S. Alps have uniform bedrock chemistry but significant tectonic and climatic gradients. West of the main topographic divide, watersheds drain schist and experience high runoff, uplift, and erosion rates. East of the main divide, watersheds drain greywacke or schist and experience lower runoff, uplift, and erosion rates. Glaciated watersheds with high erosion rates are present throughout the mountain range. Both schist and greywacke contain up to 3% metamorphic and hydrothermal calcite. Waters exhibit two-component mixing between calcite and silicate end-members when plotted as δ44Ca versus Ca/Sr. Scatter about the mixing curve is generally smaller than the analytical uncertainty of the measurements and likely reflects variability of the end-member compositions rather than fractionation. We used the mixing relationships to calculate percentages of Ca from silicate weathering. Rivers draining greywacke average 27.6% of Ca from silicate weathering with glaciated and non-glaciated watersheds yielding 41.8 and 19.5%, respectively. Rivers draining schist average 9.8% with glaciated and non-glaciated watersheds yielding 17.7 and 3.9%, respectively. Although Ca fluxes are larger west of the main divide where erosion and runoff are higher, the percentage of Ca from silicate weathering is smaller. Hence, long-term atmospheric CO2 consumption rates do not increase linearly with mechanical erosion because erosion continuously exposes fresh calcite. For non-glacial watersheds, δ44Ca and traditional Ca/Na mixing models yield similar results. However, a substantial difference exists for glacial watersheds. We think δ44Ca is a more sensitive tracer as the difference likely reflects glacial communition, which facilitates rapid and non-stoichiometric release of Ca ions from freshly cleaved silicate surfaces.¶ This study demonstrates the utility of using δ44Ca to trace silicate versus carbonate sources of riverine Ca. Our findings support previous contentions that much of the riverine Ca flux emanating from active orogens originates from carbonate weathering, which is not a sink for atmospheric CO2 over geologic timescales. However, our findings also reveal that silicate weathering and atmospheric CO2 consumption rates in glaciated watersheds are higher than previously realized.

Ca2+/calmodulin binding to PSD-95 mediates homeostatic synaptic scaling down.

PubMed

Chowdhury, Dhrubajyoti; Turner, Matthew; Patriarchi, Tommaso; Hergarden, Anne C; Anderson, David; Zhang, Yonghong; Sun, Junqing; Chen, Chao-Yin; Ames, James B; Hell, Johannes W

2018-01-04

Postsynaptic density protein-95 (PSD-95) localizes AMPA-type glutamate receptors (AMPARs) to postsynaptic sites of glutamatergic synapses. Its postsynaptic displacement is necessary for loss of AMPARs during homeostatic scaling down of synapses. Here, we demonstrate that upon Ca 2+ influx, Ca 2+ /calmodulin (Ca 2+ /CaM) binding to the N-terminus of PSD-95 mediates postsynaptic loss of PSD-95 and AMPARs during homeostatic scaling down. Our NMR structural analysis identified E17 within the PSD-95 N-terminus as important for binding to Ca 2+ /CaM by interacting with R126 on CaM. Mutating E17 to R prevented homeostatic scaling down in primary hippocampal neurons, which is rescued via charge inversion by ectopic expression of CaM R 126E , as determined by analysis of miniature excitatory postsynaptic currents. Accordingly, increased binding of Ca 2+ /CaM to PSD-95 induced by a chronic increase in Ca 2+ influx is a critical molecular event in homeostatic downscaling of glutamatergic synaptic transmission. © 2017 The Authors.

Reconstruction of Northeast Asian Deformation Integrated with Western Pacific Plate Subduction since 200 Ma

NASA Astrophysics Data System (ADS)

Liu, S.; Gurnis, M.; Ma, P.; Zhang, B.

2017-12-01

The configuration and kinematics of continental deformation and its marginal plate tectonics on the Earth's surface are intrinsic manifestations of plate-mantle coupling. The complex interactions of plate boundary forces result in plate motions that are dominated by slab pull and ridge push forces and the effects of mantle drag; these interactions also result in continental deformation with a complex basin-mountain architecture and evolution. The kinematics and evolution of the western Pacific subduction and northeast Asian continental-margin deformation are a first-order tectonic process whose nature and chronology remains controversial. This paper implements a "deep-time" reconstruction of the western Pacific subduction, continental accretion or collision and basin-mountain deformation in northeast Asia since 200 Ma based on a newly revised global plate model. The results demonstrate a NW-SE-oriented shortening from 200-137 Ma, a NWW-SEE-oriented extension from 136-101 Ma, a nearly N-S-oriented extension and uplift with a short-term NWW-SEE-oriented compressional inversion in northeast China from 100-67 Ma, and a NW-SE- and nearly N-S-oriented extension from 66 Ma to the present day. The western Pacific oceanic plate subducted forward under East Asia along Mudanjiang-Honshu Island during the Jurassic, and the trenches retreated to the Sikhote-Alin, North Shimanto, and South Shimanto zones from ca. 137-128 Ma, ca. 130-90 Ma, and in ca. 60 Ma, respectively. Our time-dependent analysis of plate motion and continental deformation coupling suggests that the multi-plate convergent motion and ocean-continent convergent orogeny were induced by advance subduction during the Jurassic and earliest Cretaceous. Our analysis also indicates that the intra-continent rifting and back-arc extension were triggered by trench retreat during the Cretaceous and that the subduction of oceanic ridge and arc were triggered by trench retreat during the Cenozoic. Therefore, reconstructing the history of plate motion and subduction and tracing the geological and deformation records in continents play a significant role in revealing the effects of complex plate motions and the interactions of plate boundary forces on plate-mantle coupling and plate motion-intracontinental deformation coupling.

Geospeedometry in the inverted metamorphic gradient of the Nestos Thrust Zone in central Rhodope (Northern Greece)

NASA Astrophysics Data System (ADS)

Cioldi, Stefania; Moulas, Evangelos; Burg, Jean-Pierre

2015-04-01

Thrust tectonics and inverted metamorphic gradients are major consequences of large and likely fast movements of crustal segments in compressional environments. The purpose of this study is to investigate the tectonic setting and the timescale of inverted metamorphic zonations related to crustal-scale thrusting. The aim is to contribute understanding the link between mechanical and thermal evolution of major thrust zones and to clarify the nature and the origin of orogenic heat. The Rhodope metamorphic complex (Northern Greece) is interpreted as a part of the Alpine-Himalaya orogenic belt and represents a collisional system with an association of both large-scale thrusting and pervasive exhumation tectonics. The Nestos Shear Zone overprints the suture boundary with a NNE-dipping pile of schists displaying inverted isograds. The inverted metamorphic zones start from chlorite-muscovite grade at the bottom and reach kyanite-sillimanite grades with migmatites in the upper structural levels. In order to reconstruct the thermo-tectonic evolution of inverted metamorphic zonation, reliable geochronological data are essential. 40Ar/39Ar geochronology with step-heating technique on white mica from micaschists provided a temporal resolution with the potential to characterize shearing. 40Ar/39Ar dating across the Nestos Shear Zone yields Late Eocene-Early Oligocene (40-30 Ma) cooling (~400-350° C) ages, which correspond to local thermo-deformation episodes linked to late and post-orogenic intrusions. U-Pb Sensitive High Resolution Ion Microprobe (SHRIMP) zircon geochronology on leucosomes from migmatitic orthogneisses were considered to estimate the age of peak metamorphic conditions, contemporaneous with anatexis. U-Pb ages of zircon rims specify regional partial melting during the Early Cretaceous (160-120 Ma). This is in disagreement with previous assertions, which argued that the formation of leucosomes in this region is Late Eocene (42-35 Ma) and implied multiple subductions and multiple metamorphic cycles during orogeny. Garnet geospeedometry considers the kinetic response of minerals and allowed estimating the absolute time-dependent thermal evolution by diffusive element profiles in garnet. Inverse-fitting numerical model considering Fractionation and Diffusion in GarnEt (FRIDGE) calculates garnet composition profiles by introducing P-T-t paths and bulk-rock composition of a specific sample. Preliminary results of Fe-Mg - Ca - Mn garnet fractionation-diffusion modelling indicate very short timescale (between 2 and 5 Ma) for peak metamorphic conditions in the Rhodope collisional system.

Petrogenesis, detrital zircon SHRIMP U-Pb geochronology, and tectonic implications of the Upper Paleoproterozoic Seosan iron formation, western Gyeonggi Massif, Korea

NASA Astrophysics Data System (ADS)

Kim, Chang Seong; Jang, Yirang; Samuel, Vinod O.; Kwon, Sanghoon; Park, Jung-Woo; Yi, Keewook; Choi, Seon-Gyu

2018-05-01

This study involves investigations on the Upper Paleoproterozoic iron formation (viz., Seosan iron formation) from the Seosan Group, Gyeonggi Massif of the southwestern Korean Peninsula. It occurs as thin banded layers within meta-arkosic sandstone, formed by alternating processes of chemical (hydrothermal) and detrital depositions under a shallow marine environment. It mainly consists of alternating layers of iron oxides, mostly hematite, and quartz. Minor amounts of magnetite surrounded by muscovite, clinopyroxene and amphibole indicate hydrothermal alteration since its formation. Meta-arkosic sandstone is composed of recrystallized or porphyroclastic quartz and microcline, with small amounts of hematite and pyrite clusters. The Seosan iron formation has high contents of total Fe2O3 and SiO2 with positive Eu anomalies similar to those of other Precambrian banded iron formations, and its formation is clearly related to hydrothermal alteration since its deposition. Detrital zircon SHRIMP U-Pb geochronology data from a meta-arkosic sandstone (SN-1) and an iron formation (SN-2) show mainly two age groups of ca. 2.5 Ga and ca. 1.9-1.75 Ga. This together with intrusion age of the granite gneiss (ca. 1.70-1.65 Ga) clearly indicate that the iron formations were deposited during the Upper Paleoproterozoic. The dominant Paleoproterozoic detrital zircon bimodal age peaks preserved in the Seosan iron formation compare well with those from the South China Craton sedimentary basins, reflecting global tectonic events related to the Columbia supercontinent in East Asia.

Investigation of spreading center ecolution by joint inversion of seafloor magnetic anomaly and tectonic fabric data

NASA Technical Reports Server (NTRS)

Shoberg, Tom; Stein, Seth

1994-01-01

Spreading center segments that have experienced a complex tectonic history including rift propagation may have a complicated signature in bathymetric and magnetic anomaly data. To gain insight into the history of such regions, we have developed techniques in which both the magnetic anomaly patterns and seafloor fabric trends are predicted theoretically, and the combined predictions are compared numerically with the data to estimate best fitting parameters for the propagation history. Fitting functions are constructed to help determine which model best matches the digitized fabric and magnetic anomaly data. Such functions offer statistical criteria for choosing the best fit model. We use this approach to resolve the propagation history of the Cobb Offset along the Juan de Fuca ridge. In this example, the magnetic anomaly data prove more useful in defining the geometry of the propagation events, while the fabric, with its greater temporal resolution, is more useful for constraining the rate of propagation. It thus appears that joint inversion of magnetic and seafloor fabric data can be valuable in tectonic analyses.

Thermal evolution and exhumation of deep-level batholithic exposures, southernmost Sierra Nevada, California

USGS Publications Warehouse

Saleeby, J.; Farley, K.A.; Kistler, R.W.; Fleck, R.J.

2007-01-01

The Tehachapi complex lies at the southern end of the Sierra Nevada batholith adjacent to the Neogene-Quaternary Garlock fault. The complex is composed principally of high-pressure (8-10 kbar) Cretaceous batholithic rocks, and it represents the deepest exposed levels of a continuous oblique crustal section through the southern Sierra Nevada batholith. Over the southern ???100 km of this section, structural/petrologic continuity and geochronological data indicate that ???35 km of felsic to intermediate-composition crust was generated by copious arc magmatism primarily between 105 and 99 Ma. In the Tehachapi complex, these batholithic rocks intrude and are bounded to the west by similar-composition gneissic-textured high-pressure batholithic rocks emplaced at ca. 115-110 Ma. This lower crustal complex is bounded below by a regional thrust system, which in Late Cretaceous time tectonically eroded the underlying mantle lithosphere, and in series displaced and underplated the Rand Schist subduction assemblage by low-angle slip from the outboard Franciscan trench. Geophysical and mantle xenolith studies indicate that the remnants of this shallow subduction thrust descend northward through the crust and into the mantle, leaving the mantle lithosphere intact beneath the greater Sierra Nevada batholith. This north-dipping regional structure records an inflection in the Farallon plate, which was segmented into a shallow subduc-tion trajectory to the south and a normal steeper trajectory to the north. We combine new and published data from a broad spectrum of thermochronom-eters that together form a coherent data array constraining the thermal evolution of the complex. Integration of these data with published thermobarometric and petro-genetic data also constrains the tectonically driven decompression and exhumation history of the complex. The timing of arc magmatic construction of the complex, as denoted above, is resolved by a large body of U/Pb zircon ages. High-confidence thermochronometric data track a single retrogressing path commencing from widely established solidus conditions at ca. 100 Ma, and traversing through time-temperature space as follows: (1) Sm/Nd garnet ???770-680 ??C at ca. 102-95 Ma, (2) U/Pb titanite ???750-600 ??C at ca. 102-95 Ma, (3) Ar/Ar hornblende ???570-490 ??C at ca. 94-91 Ma, (4) Rb/Sr biotite ???390-260 ??C at ca. 90-86 Ma, (5) Ar/Ar biotite ???320-240 ??C at ca. 88-85 Ma, and (6) (U-Th)/He zircon ???230-170 ??C at ca. 88-83 Ma. Additional stratigraphic constraints place the complex at surface conditions in Paleocene-early Eocene time (ca. 66-55 Ma). Integration of these results with thermobarometric and structural data, including published data on the underlying Rand Schist, reveals a profound tectonic event whereby rapid cooling and exhumation at rates potentially as high as 100s ??C/m.y. and >5 mm/yr initiated at ca. 98 Ma and peaked between 96 and 94 Ma. Between 93 and 85 Ma, cooling rates remained high, but decelerated with or without significant exhumation. Subsequent cooling and exhumation rates are poorly constrained but were much slower and ultimately resulted in Paleocene-Eocene surface exposure. Initial rapid exhumation and cooling are hypothesized to have been driven by abrupt flattening in the corresponding segment of the Farallon plate and the resulting tectonic erosion of the underlying mantle lithosphere. Protolith as well as meta-morphic pressure-temperature and age constraints on the Rand Schist indicate its rapid low-angle subduction between 93 and 88 Ma. Comparison of the Rand Schist and Tehachapi complex pressure-temperature-time paths in conjunction with structural relations strongly suggest that the schist ascended the equivalent of ???4 kbar relative to the Tehachapi complex by low-angle normal displacement along the Rand fault between 88 and 80 Ma to attain its current underplated structural position. Such extensional tectonism is hypothesized to have been driven by slab rollback

A petrological study of Paleoarchean rocks of the Onverwacht Group: New insights into the geologic evolution of the Barberton Greenstone Belt, South Africa

NASA Astrophysics Data System (ADS)

Grosch, E. G.; Mcloughlin, N.; Abu-Alam, T. S.; Vidal, O.

2012-12-01

This study presents a multi-disciplinary petrological approach applied to surface samples and a total of 800 m of scientific drill core that furthers our understanding of the geologic evolution of the ca. 3.5 to 3.2 Ga Onverwacht Group of the Barberton greenstone belt (BGB), South Africa. Detrital zircon grains in coarse (diamictite) to fine-grained clastic sedimentary rocks of the Noisy formation (drill core KD2a) that unconformably overlies the volcanic ca. 3472 Ma Hooggenoeg Formation, are investigated by laser ablation LA-ICP-MS to constrain their 207Pb/206Pb ages for depositional age and provenance. A wide range in 207Pb/206Pb ages between ca. 3600 and 3430 Ma is reported, corresponding to surrounding TTG plutons and the ca.3667-3223 Ma Ancient Gneiss Complex. The youngest detrital zircon grain identified has an age of 3432 ± 10 Ma. Given the short time interval for a major change in geologic environment between ca. 3472 Ma and ca. 3432 Ma, it is argued here, that the Noisy formation is the earliest tectonic basin in the BGB, which developed during major tectonic uplift at ca. 3432 Ma. In the overlying ca. 3334 Ma Kromberg type-section, application of a chlorite thermodynamic multi-equilibrium calculation, dioctahedral mica hydration-temperature curve and pseudosection modelling, indicates a wide range in metamorphic conditions from sub-greenschist to the uppermost greenschist facies across the Kromberg type-section. A central mylonitic fuchsite-bearing zone, referred to as the Kromberg Section Mylonites, records at least two metamorphic events: a high-T, low-P (420 ± 30oC, < 3kbar) metamorphism, and a lower-T event (T = 240-350oC, P = 2.9 ± 0.15kbar) related to retrograde metamorphism. An inverted metamorphic field gradient is documented beneath the KSM suggesting thrust repetition of the Kromberg sequence over the clastic rocks of the Noisy formation at ca. 3.2 Ga. This study also presents the first SIMS multiple sulfur isotope dataset on sulfides from the BGB and is used to test current models of mid-Archean biogeochemical sulfur cycling. In-situ δ34SCDT and Δ33S values of volcanic, detrital, diagenetic and hydrothermal pyrite of the Kromberg and Noisy Formations are presented. The Kromberg cherts and mafic-ultramafic hydrothermal vein pyrites exhibit Δ33S of -0.20 to +2.50‰, and δ34SCDT from -6.00 to +1.50‰ recording mixing between atmospheric sulfur and hydrothermal magmatic fluids. The Noisy sedimentary sequence contains detrital and diagenetic pyrites with a significant variation in Δ33S of -0.62 to +1.4‰ and δ34SCDT between -7.00 and +12.6‰ in the upper turbidite unit, to more narrow isotopic ranges with magmatic-atmospheric values in the underlying polymictitic diamictite. A sedimentary quartz-pyrite vein in the diamictite records the largest range and most negative δ34SCDT values so far reported from an Archean terrain (δ34SCDT = -55.04 to +27.46‰), and suggests shallow-level boiling and hydrogen release into early (ca. 3432 Ma) tectonic sedimentary basins during sulfide precipitation and a new possible environment for early microbial life.

Red/blue-shift dual-directional regulation of α-(Ca, Sr)2SiO4:Eu(2+) phosphors resulting from the incorporation content of Eu(2+)/Sr(2+) ions.

PubMed

Lu, Zhijuan; Mao, Zhiyong; Chen, Jingjing; Wang, Dajian

2015-09-21

In this work, tunable emission from green to red and the inverse tuning from red to green in α-(Ca, Sr)2SiO4:Eu(2+) phosphors were demonstrated magically by varying the incorporation content of Eu(2+) and Sr(2+) ions, respectively. The tunable emission properties and the tuning mechanism of red-shift resulting from the Eu(2+) content as well as that of blue-shift induced by the Sr(2+) content were investigated in detail. As a result of fine-controlling the incorporation content of Eu(2+), the emission peak red-shifts from 541 nm to 640 nm. On the other hand, the emission peak inversely blue-shifts from 640 nm to 546 nm through fine-adjusting the incorporation content of Sr(2+). The excellent tuning characteristics for α-(Ca, Sr)2SiO4:Eu(2+) phosphors presented in this work exhibited their various application prospects in solid-state lighting combining with a blue chip or a near-UV chip.

Microstructural evolution of garnet in a greenschist facies transpression zone

NASA Astrophysics Data System (ADS)

Massey, M. A.; Prior, D. J.; Moecher, D. P.

2007-12-01

Natural observations, laboratory experiments, and theoretical modeling support the interpretation of Grt plasticity in the lower crust and upper mantle; however, these processes are thought to be of little importance in shallow to middle crustal levels. Multiple textural varieties of Grt from the western boundary (Mt. Dumplin high strain zone) of an upper greenschist facies dextral transpression zone in southern New England, USA, display mesoscopic and microscopic evidence of syn-tectonic deformation and recrystallization. These microstructures were examined further by optical microscopy, electron probe microanalysis, orientation contrast imaging (OCI), and automated electron backscatter diffraction (EBSD) in order to understand possible low-grade deformation mechanisms and their significance. The N-S-striking shear zone dips steeply W, the mylonitic foliation is defined by aligned Ms- Chl-Rt, layers of Qtz and fine-grained Grt; Qtz-Chl-Ms and fine-grained Grt aggregates define lineations that plunge moderately SW. S-C-C¡¦ fabrics, asymmetric folds and porphyroclasts (delta- and sigma-type) are well developed on foliation-normal/lineation-parallel planes, and display sinistral kinematics; surfaces normal to foliation and normal to lineation exhibit strong asymmetries that indicate normal motion. Pre-tectonic mineral parageneses consist of St pseudomorphed by Chl-Ms-Ctd, Als pseudomorphed by Ms, and coarse-grained Grt and Ab porphyroclasts with associated asymmetric tails. Grt is manifest as three types: 1) equant Grt porphyroclasts; 2) elongate Grt aggregates consisting of 50-100 Ým equant Grt porphyroblasts; 3) type 1-type 2 transitional Grt morphology. Elemental x-ray mapping of Ca and Mn reveals at least two periods of growth in Grt types 1 and 3, and one period of growth in type 2 that correlates with type 1 and 3 rims; Mg is completely homogenized. Detailed mapping of type 3 Grt cores reveals ¡¥fractured¡¦ Ca-enriched cores ¡¥healed¡¦ with Ca- depleted composition. OCI of type 1 Grt shows no internal substructure. OCI of type 2 Grt also shows rare internal substructure (finer-grained equant inclusions with low angle boundaries), and EBSD shows aggregates have CPO symmetrical to tectonic fabric (parallel to lineation), high angle grain boundaries, and neighbor- neighbor grain pairs correlate with random grain pair distributions. Type 2 Grt also displays ¡¥stacking¡¦ structures where individual porphyroblasts are stacked vertically and grain boundaries are at low angle. OCI of type 3 Grt shows considerable internal substructure of three varieties: A) substructure boundaries that coincide with Ca-depleted compositions in cores; B) 50-100 Ým equant substructures included in rims; C) substructure boundaries in rims that ¡¥nucleate¡¦ from substructure A boundaries in cores. Detailed EBSD traverses across all substructure boundaries indicate rotation around rational crystallographic axes. Observations suggest that early amphibolite facies Grt (type 1 and 3 cores) was deformed non-penetratively by plastic deformation or sub-critical fracture (type 3 Grt, substructure A). Type 2 Grt nucleated pre- to syn-tectonically, at least partially through the consumption of type 3 Grt porphyroclasts, and was included in type 1 and 3 rims by rigid body rotations (substructure B). Substructures C in type 3 Grt rims are inherited from pre-existing crystallographic anisotropies in cores (substructure A). Additionally, type 2 Grt was deformed syn-tectonically to produce CPOs, likely as a result of flattening associated with transpression.

The central role of the Hikurangi Plateau in the Cenozoic tectonics of New Zealand and the Southwest Pacific

NASA Astrophysics Data System (ADS)

Reyners, Martin

2013-01-01

Recent work involving relocation of New Zealand seismicity using a nationwide 3-D seismic velocity model has located the subducted western edge of the Hikurangi Plateau. Both the thickness (ca. 35 km) and the area of the plateau subducted in the Cenozoic (ca. 287,000 km2) are much larger than previously supposed. From ca. 45 Ma, the westernmost tip of the plateau controlled the transition at the Pacific/Australia plate boundary from subduction to the north to Emerald Basin opening to the south. At ca. 23 Ma, curvature of the subduction zone against the western flank of the buoyant plateau became extreme, and a Subduction-Transform Edge Propagator (STEP fault) developed along the western edge of the plateau. This STEP fault corresponds to the Alpine Fault, and the resulting Pacific slab edge is currently defined by intermediate-depth seismicity under the northernmost South Island. Alpine STEP fault propagation was terminated at ca. 15 Ma, when the western edge of the plateau became parallel to the trench, and thus STEP fault formation was no longer favoured. Wholesale subduction of the plateau at the Hikurangi subduction zone began at ca. 10 Ma. The development of a subduction décollement above the plateau mechanically favoured deformation within the overlying Australian plate continental crust. This led to inception of the Marlborough fault system at ca. 7 Ma, and the North Island fault system at 1-2 Ma. At ca. 7 Ma, the western edge of the converging plateau again became more normal to the trench, and there is evidence supporting the development of a second STEP fault beneath the Taupo Volcanic Zone until ca. 3 Ma. Both episodes of STEP fault development at the plateau edge led to rapid slab rollback, and correspond closely with episodes of backarc basin opening to the north in the wider Southwest Pacific. The Cenozoic tectonics of New Zealand and the Southwest Pacific has been strongly influenced not only by the resistance to subduction of the buoyant Hikurangi Plateau, but also by the shape of its western edge and changing angle of attack of this edge at the plate boundary.

The ternary system K2SO4MgSO4CaSO4

USGS Publications Warehouse

Rowe, J.J.; Morey, G.W.; Silber, C.C.

1967-01-01

Melting and subsolidus relations in the system K2SO4MgSO4CaSO4 were studied using heating-cooling curves, differential thermal analysis, optics, X-ray diffraction at room and high temperatures and by quenching techniques. Previous investigators were unable to study the binary MgSO4CaSO4 system and the adjacent area in the ternary system because of the decomposition of MgSO4 and CaSO4 at high temperatures. This problem was partly overcome by a novel sealed-tube quenching method, by hydrothermal synthesis, and by long-time heating in the solidus. As a result of this study, we found: (1) a new compound, CaSO4??3MgSO4 (m.p. 1201??C) with a field extending into the ternary system; (2) a high temperature form of MgSO4 with a sluggishly reversible inversion. An X-ray diffraction pattern for this polymorphic form is given; (3) the inversion of ??-CaSO4 (anhydrite) to ??-CaSO4 at 1195??C, in agreement with grahmann; (1) (4) the melting point of MgSO4 is 1136??C and that of CaSO4 is 1462??C (using sealed tube methods to prevent decomposition of the sulphates); (5) calcium langbeinite (K2SO4??2CaSO4) is the only compound in the K2SO4CaSO4 binary system. This resolved discrepancies in the results of previous investigators; (6) a continuous solid solution series between congruently melting K2SOP4??2MgSO4 (langbeinite) and incongruently melting K2SO4??2CaSO4 (calcium langbeinite); (7) the liquidus in the ternary system consists of primary phase fields of K2SO4, MgSO4, CaSO4, langbeinite-calcium langbeinite solid solution, and CaSO4??3MgSO4. The CaSO4 field extends over a large portion of the system. Previously reported fields for the compounds (K2SO4??MgSO4??nCaSO4), K2SO4??3CaSO4 and K2SO4??CaSO4 were not found; (8) a minimum in the ternary system at: 740??C, 25% MgSO4, 6% CaSO4, 69% K2SO4; and ternary eutectics at 882??C, 49% MgSO4, 19% CaSO4, 32% K2SO4; and 880??, 67??5% MgSO4, 5% CaSO4, 27??5% K2SO4. ?? 1967.

New Insights into Tectonics of the Saint Elias, Alaska, Region Based on Local Seismicity and Tomography

NASA Astrophysics Data System (ADS)

Ruppert, N. A.; Zabelina, I.; Freymueller, J. T.

2013-12-01

Saint Elias Mountains in southern Alaska are manifestation of ongoing tectonic processes that include collision of the Yakutat block with and subduction of the Yakutat block and Pacific plate under the North American plate. Interaction of these tectonic blocks and plates is complex and not well understood. In 2005 and 2006 a network of 22 broadband seismic sites was installed in the region as part of the SainT Elias TEctonics and Erosion Project (STEEP), a five-year multi-disciplinary study that addressed evolution of the highest coastal mountain range on Earth. High quality seismic data provides unique insights into earthquake occurrence and velocity structure of the region. Local earthquake data recorded between 2005 and 2010 became a foundation for detailed study of seismotectonic features and crustal velocities. The highest concentration of seismicity follows the Chugach-St.Elias fault, a major on land tectonic structure in the region. This fault is also delineated in tomographic images as a distinct contrast between lower velocities to the south and higher velocities to the north. The low-velocity region corresponds to the rapidly-uplifted and exhumed sediments on the south side of the range. Earthquake source parameters indicate high degree of compression and undertrusting processes along the coastal area, consistent with multiple thrust structures mapped from geological studies in the region. Tomographic inversion reveals velocity anomalies that correlate with sedimentary basins, volcanic features and subducting Yakutat block. We will present precise earthquake locations and source parameters recorded with the STEEP and regional seismic network along with the results of P- and S-wave tomographic inversion.

Multifaulting in a tectonic syntaxis revealed by InSAR: The case of the Ziarat earthquake sequence (Pakistan)

NASA Astrophysics Data System (ADS)

Pinel-Puysségur, B.; Grandin, R.; Bollinger, L.; Baudry, C.

2014-07-01

On 28-29 October 2008, within 12 h, two similar Mw = 6.4 strike-slip earthquakes struck Baluchistan (Pakistan), as part of a complex seismic sequence. Interferometric Synthetic Aperture Radar (InSAR) data reveal that the peak of surface displacement is near the Ziarat anticline, a large active fold affected by Quaternary strike-slip faulting. All coseismic interferograms integrate the deformation due to both earthquakes. As their causative faults ruptured close to each other, the individual signals cannot be separated. According to their focal mechanisms, each earthquake may have activated a NE-SW sinistral or a NW-SE dextral fault segment, which leads to four possible scenarios of fault orientations. A nonlinear inversion of the InSAR data set allows rejecting two scenarios. The best slip distributions on the two fault segments for the two remaining scenarios are determined by linear inversion. Stress-change modeling favors a scenario involving two abutting conjugate strike-slip faults. Two other fault segments accommodated left-lateral strike slip during the seismic sequence. The activated fault system includes multiple fault segments with different orientations and little surface expression. This may highlight, at a smaller scale, the distributed, possibly transient character of deformation within a broader right-lateral shear zone. It suggests that the activated faults delineate a small tectonic block extruding and subtly rotating within the shear zone. It occurs in the vicinity of the local tectonic syntaxis where orogenic structures sharply turn around a vertical axis. These mechanisms could participate in the long-term migration of active tectonic structures within this kinematically unstable tectonic syntaxis.

Plio-Quaternary stress states in NE Iran: Kopeh Dagh and Allah Dagh-Binalud mountain ranges

NASA Astrophysics Data System (ADS)

Shabanian, Esmaeil; Bellier, Olivier; Abbassi, Mohammad R.; Siame, Lionel; Farbod, Yassaman

2010-01-01

NE Iran, including the Kopeh Dagh and Allah Dagh-Binalud deformation domains, comprises the northeastern boundary of the Arabia-Eurasia collision zone. This study focuses on the evolution of the Plio-Quaternary tectonic regimes of northeast Iran. We present evidence for drastic temporal changes in the stress state by inversion of both geologically and seismically determined fault slip vectors. The inversions of fault kinematics data reveal distinct temporal changes in states of stress during the Plio-Quaternary (since ˜ 5 Ma). The paleostress state is characterized by a regional transpressional tectonic regime with a mean N140 ± 10°E trending horizontal maximum stress axis ( σ1). The youngest (modern) state of stress shows two distinct strike-slip and compressional tectonic regimes with a regional mean of N030 ± 15°E trending horizontal σ1. The change from the paleostress to modern stress states has occurred through an intermediate stress field characterized by a mean regional N trending σ1. The inversion analysis of earthquake focal mechanisms reveals a homogeneous, transpressional tectonic regime with a regional N023 ± 5°E trending σ1. The modern stress state, deduced from the youngest fault kinematics data, is in close agreement with the present-day stress state given by the inversions of earthquake focal mechanisms. According to our data and the deduced results, in northeast Iran, the Arabia-Eurasia convergence is taken up by strike-slip faulting along NE trending left-lateral and NNW trending right-lateral faults, as well as reverse to oblique-slip reverse faulting along NW trending faults. Such a structural assemblage is involved in a mechanically compatible and homogeneous modern stress field. This implies that no strain and/or stress partitioning or systematic block rotations have occurred in the Kopeh Dagh and Allah Dagh-Binalud deformation domains. The Plio-Quaternary stress changes documented in this paper call into question the extrapolation of the present-day seismic and GPS-derived deformation rates over geological time intervals encompassing tens of millions of years.

Geochronology and geochemistry of tuff beds from the Shicaohe Formation of Shennongjia Group and tectonic evolution in the northern Yangtze Block, South China

NASA Astrophysics Data System (ADS)

Du, Qiuding; Wang, Zhengjiang; Wang, Jian; Deng, Qi; Yang, Fei

2016-03-01

Meso- to Neoproterozoic magmatic events are widespread in the Yangtze Block. The geochronology and tectonic significance of the Shennongjia Group in the Yangtze Block are still highly controversial. An integrated geochronology and geochemistry approach provides new insights into the geochronological framework, tectonic setting, magmatic events, and basin evolution of the northern Yangtze Block. Our new precise sensitive high-resolution ion microprobe U-Pb data indicate a deposition age of 1180 ± 15 Ma for the Shicaohe Formation subalkaline basaltic tuff that is geochemically similar to modern intracontinental rift volcanic rocks. The integration of available geochemical data together with our new U-Pb ages indicates the Shicaohe Formation subalkaline basaltic tuff formed ca. 1180 in a continental rift-related setting on a passive continental margin. The Shennongjia Group is topped by the Zhengjiaya Formation volcanic sequence, indicating arc-related igneous events at 1103 Ma. The transition of the late Mesoproterozoic tectonic regime from intracontinental extension to convergence occurred between ca. 1180 and 1103 Ma in the northern Yangtze Block. Tectonic evolution in the Neoproterozoic led to accretion along the northern margin of the Yangtze Block. These results provide geochronological evidence, which is of utmost importance for reconfiguration of the chronostratigraphic framework and for promoting research on Mesoproterozoic strata in China, thereby increasing understanding of magmatic events and basin evolutionary history in the northern Yangtze Block.

Unraveling tectonics and climate forcing in the late-Neogene exhumation history of South Alaska

NASA Astrophysics Data System (ADS)

Valla, Pierre; Champagnac, Jean-Daniel; Shuster, David; Herman, Frédéric; Giuditta Fellin, Maria

2015-04-01

The southern Alaska range presents an ideal setting to study the complex interactions between tectonics, climate and surface processes in landscape evolution. It exhibits active tectonics with the ongoing subduction/collision between Pacific and North America, and major active seismogenic reverse and strike-slip faults. The alpine landscape, rugged topography and the important ice-coverage at present reveal a strong glacial imprint associated with high erosion and sediment transport rates. Therefore, the relative importance of climatically-driven glacial erosion and tectonics for the observed late-exhumation history appears to be quite complex to decipher. Here, we first perform a formal inversion of an extensive bedrock thermochronological dataset from the literature to quantify the large-scale 20-Myr exhumation history over the entire southern Alaska. We show that almost half of the variability within the thermochronological record can be explained by modern annual precipitations spatial distribution, the residuals clearly evidencing localized exhumation along major tectonic structures of the frontal fold and thrust belt. Our results confirm high exhumation rates in the St Elias "syntaxis" and frontal zones for the last 0-2 Myr, where major ice fields and high precipitation rates likely sustained high exhumation rates; however the impact of late Cenozoic glaciations is difficult to constrain because of the low resolution on the exhumation history older than ~2 Myr. On the contrary, our inversion outcomes highlight that north of the Bagley Icefield the long-term exhumation has remained quite slow and continuous over the last ~20 Myr, with no late-stage signal of exhumation change since the onset of glaciations despite a clear glacial imprint on the landscape. We thus focus on the Granite Range (Wrangell-St Elias National Park, Alaska), an area presenting a strong glacial imprint but minor tectonic activity with only localized brittle deformation. We sampled four elevation profiles over an East-West transect for low-temperature thermochrometry. Apatite (U-Th-Sm)/He dating provides ages between ~10 and 30 Ma, in agreement with published data, and shows apparent low long-term exhumation rates (~0.1 km/Myr). 4He/3He thermochronometry on a subset of samples reveals a more complex exhumation history, with a significant increase in exhumation since ~6-4 Ma that we relate to the early onset of glaciations and associated glacial erosion processes. Our results, in agreement with offshore sediment records, thus confirm an early glacial activity and associated erosion response in Alaska, well before the onset of Pliocene-Pleistocene Northern Hemisphere glaciations.

Petrology and geochronology of Mesoproterozoic basement of the Mount Rogers area of southwestern Virginia and northwestern North Carolina: Implications for the Precambrian tectonic evolution of the southern Blue Ridge province

USGS Publications Warehouse

Tollo, Richard P.; Aleinikoff, John N.; Dickin, Alan P.; Radwany, Molly S.; Southworth, C. Scott; Fanning, C. Mark

2017-01-01

Results from new geologic mapping, SHRIMP U-Pb geochronology, and petrologic studies indicate that Mesoproterozoic basement in the northern French Broad massif near Mount Rogers consists of multiple, mostly granitic plutons, map- and outcrop-scale xenoliths of pre-existing crustal rocks, and remnants of formerly overlying meta-sedimentary lithologies. Zircon and titanite ages demonstrate that these rocks collectively record nearly 350 m.y. of tectonic evolution including periods of igneous intrusion at ca. 1190 to 1130 Ma (Early Magmatic Suite) and ca. 1075 to 1030 Ma (Late Magmatic Suite) and three episodes of regional metamorphism at ca. 1170 to 1140, 1070 to 1020, and 1000 to 970 Ma. The existence of ca. 1.3 Ga age crust is indicated by (1) orthogranofels of ca. 1.32 Ga age in a map-scale xenolith, (2) inherited zircons of ca. 1.33 to 1.29 Ga age in Early Magmatic Suite plutons, and (3) ca. 1.36 to 1.30 Ga age detrital zircons in meta-sedimentary lithologies. Mineral assemblages developed in amphibolites and granofelses indicate that metamorphism during both Mesoproterozoic episodes occurred at upper amphibolite- to lower granulite-facies conditions. Syn-orogenic Early Magmatic Suite plutons emplaced at ca. 1190 to 1145 Ma are characterized by high-K, variably magnesian, dominantly calc-alkalic compositions, and have trace-element characteristics indicative of continental-arc magmatic origin involving melting of thick continental crust. In contrast, ca. 1140 Ma age quartz syenite displays A-type features indicating derivation from depleted crustal sources with increased mantle input during waning stages of regional contraction. Plutons of the compositionally bimodal Late Magmatic Suite include (1) ca. 1060 Ma meta-granite with geochemical characteristics transitional between silicic rocks of arc systems and post-collisional granites of A-type lineage, and (2) ca. 1055 Ma monzodioritic rocks with A-type compositional characteristics that likely reflect derivation from fertile, mafic sources in the lower crust. Collectively, these data suggest that Mesoproterozoic rocks of the study area preserve evidence of multiple orogenic episodes that likely involved continental-arc development and deformation at ca. 1150 Ma followed by crustal thickening at ca. 1060 Ma. Field relations and geochronologic data indicate that regional uplift and sedimentation occurred at ca. 1100 Ma between the two episodes of overlapping magmatism and orogenesis. The nature and timing of Mesoproterozoic events recorded in basement rocks of the study area illustrate significant differences in the lithologic assemblages and geologic history preserved by Mesoproterozoic basement of the adjacent Shenandoah and French Broad massifs, suggesting that the Blue Ridge massifs occupied different locations within the regional Grenville-age orogen until about 1070 Ma when the effects of Ottawan-age tectonics began to affect both areas. The near ubiquity of Ottawan-age orogenic activity recorded in Mesoproterozoic rocks of the Blue Ridge, other Appalachian inliers such as the New Jersey Highlands, and the Grenville province of Canada, including the Adirondacks, suggests that these formerly disparate terranes were amalgamated to form a common, regional orogen by this time.

Paleozoic intrusive rocks from the Dunhuang tectonic belt, NW China: Constraints on the tectonic evolution of the southernmost Central Asian Orogenic Belt

NASA Astrophysics Data System (ADS)

Zhao, Yan; Sun, Yong; Diwu, Chunrong; Zhu, Tao; Ao, Wenhao; Zhang, Hong; Yan, Jianghao

2017-05-01

The Dunhuang tectonic belt (DTB) is of great importance for understanding the tectonic evolution of the southernmost Central Asian Orogenic Belt (CAOB). In this study, the temporal-spatial distribution, petrogenesis and tectonic setting of the Paleozoic representative intrusive rocks from the DTB were systematically investigated to discuss crustal evolution history and tectonic regime of the DTB during Paleozoic. Our results reveal that the Paleozoic magmatism within the DTB can be broadly divided into two distinct episodes of early Paleozoic and late Paleozoic. The early Paleozoic intrusive rocks, represented by a suite metaluminous-slight peraluminous and medium- to high-K calc-alkaline I-type granitoids crystallized at Silurian (ca. 430-410 Ma), are predominantly distributed along the northern part of the DTB. They were probably produced with mineral assemblage of eclogite or garnet + amphibole + rutile in the residue, and were derived from magma mixing source of depleted mantle materials with various proportions of Archean-Mesoproterozoic continental crust. The late Paleozoic intrusive rocks can be further subdivided into two stages of late Devonian stage (ca. 370-360 Ma) and middle Carboniferous stage (ca. 335-315 Ma). The former stage is predominated by metaluminous to slight peraluminous and low-K tholeiite to high-K calc-alkaline I-type granitic rocks distributed in the central part of the DTB. They were also generated with mineral assemblage of amphibolite- to eclogite-facies in the residue, and originated from magma source of depleted mantle materials mixed with different degrees of old continental crust. The later stage is represented by adakite and alkali-rich granite exposed in the southern part of the DTB. The alkali-rich granites studied in this paper were possibly produced with mineral assemblage of granulite-facies in the residue and were generated by partial melting of thickened lower continental crust. Zircon Hf isotopes and field distribution of those Paleozoic intrusive rocks reveal that both the Silurian and the late Devonian magmatic activities predominantly represent crustal growth processes in the DTB, accompanied by different degrees of reworking of pre-existing continental crust. However, the middle Carboniferous (ca. 335-315 Ma) magmatic activity reflects a crustal reworking process. The Silurian and late Devonian intrusive rocks were most likely formed in the arc-related subduction zones, whereas, the middle Carboniferous intrusive rocks were possibly formed in a transitional tectonic setting from compression to extension, representing the final stage of Paleozoic orogeny in the DTB. These Paleozoic magmatic rocks further suggest that the DTB has reactivated from a stable block to an orogen and undergone two episodes (the early Paleozoic and the late Paleozoic) of orogeny during Paleozoic. It represents a Paleozoic accretionary orogen of the southernmost margin of the CAOB between the Tarim Craton and North China Craton, and tectonically extends northward to the Beishan orogen and westward to the eastern South Tianshan Belt.

Tectonic plates, D (double prime) thermal structure, and the nature of mantle plumes

NASA Technical Reports Server (NTRS)

Lenardic, A.; Kaula, W. M.

1994-01-01

It is proposed that subducting tectonic plates can affect the nature of thermal mantle plumes by determining the temperature drop across a plume source layer. The temperature drop affects source layer stability and the morphology of plumes emitted from it. Numerical models are presented to demonstrate how introduction of platelike behavior in a convecting temperature dependent medium, driven by a combination of internal and basal heating, can increase the temperature drop across the lower boundary layer. The temperature drop increases dramatically following introduction of platelike behavior due to formation of a cold temperature inversion above the lower boundary layer. This thermal inversion, induced by deposition of upper boundary layer material to the system base, decays in time, but the temperature drop across the lower boundary layer always remains considerably higher than in models lacking platelike behavior. On the basis of model-inferred boundary layer temperature drops and previous studies of plume dynamics, we argue that generally accepted notions as to the nature of mantle plumes on Earth may hinge on the presence of plates. The implication for Mars and Venus, planets apparently lacking plate tectonics, is that mantle plumes of these planets may differ morphologically from those of Earth. A corollary model-based argument is that as a result of slab-induced thermal inversions above the core mantle boundary the lower most mantle may be subadiabatic, on average (in space and time), if major plate reorganization timescales are less than those acquired to diffuse newly deposited slab material.

Ambient Noise Tomography of central Java, with Transdimensional Bayesian Inversion

NASA Astrophysics Data System (ADS)

Zulhan, Zulfakriza; Saygin, Erdinc; Cummins, Phil; Widiyantoro, Sri; Nugraha, Andri Dian; Luehr, Birger-G.; Bodin, Thomas

2014-05-01

Delineating the crustal structure of central Java is crucial for understanding its complex tectonic setting. However, seismic imaging of the strong heterogeneity typical of such a tectonically active region can be challenging, particularly in the upper crust where velocity contrasts are strongest and steep body wave ray-paths provide poor resolution. We have applied ambient noise cross correlation of pair stations in central Java, Indonesia by using the MERapi Amphibious EXperiment (MERAMEX) dataset. The data were collected between May to October 2004. We used 120 of 134 temporary seismic stations for about 150 days of observation, which covered central Java. More than 5000 Rayleigh wave Green's function were extracted by cross-correlating the noise simultaneously recorded at available station pairs. We applied a fully nonlinear 2D Bayesian inversion technique to the retrieved travel times. Features in the derived tomographic images correlate well with previous studies, and some shallow structures that were not evident in previous studies are clearly imaged with Ambient Noise Tomography. The Kendeng Basin and several active volcanoes appear with very low group velocities, and anomalies with relatively high velocities can be interpreted in terms of crustal sutures and/or surface geological features.

Thin-section ratiometric Ca2+ images obtained by optical sectioning of fura-2 loaded mast cells

PubMed Central

1992-01-01

The availability of the ratiometric Ca2+ indicator dyes, fura-2, and indo-1, and advances in digital imaging and computer technology have made it possible to detect Ca2+ changes in single cells with high temporal and spatial resolution. However, the optical properties of the conventional epifluorescence microscope do not produce a perfect image of the specimen. Instead, the observed image is a spatial low pass filtered version of the object and is contaminated with out of focus information. As a result, the image has reduced contrast and an increased depth of field. This problem is especially important for measurements of localized Ca2+ concentrations. One solution to this problem is to use a scanning confocal microscope which only detects in focus information, but this approach has several disadvantages for low light fluorescence measurements in living cells. An alternative approach is to use digital image processing and a deblurring algorithm to remove the out of focus information by using a knowledge of the point spread function of the microscope. All of these algorithms require a stack of two-dimensional images taken at different focal planes, although the "nearest neighbor deblurring" algorithm only requires one image above and below the image plane. We have used a modification of this scheme to construct a simple inverse filter, which extracts optical sections comparable to those of the nearest neighbors scheme, but without the need for adjacent image sections. We have used this "no neighbors" processing scheme to deblur images of fura-2-loaded mast cells from beige mice and generate high resolution ratiometric Ca2+ images of thin sections through the cell. The shallow depth of field of these images is demonstrated by taking pairs of images at different focal planes, 0.5-microns apart. The secretory granules, which exclude the fura-2, appear in focus in all sections and distinct changes in their size and shape can be seen in adjacent sections. In addition, we show, with the aid of model objects, how the combination of inverse filtering and ratiometric imaging corrects for some of the inherent limitations of using an inverse filter and can be used for quantitative measurements of localized Ca2+ gradients. With this technique, we can observe Ca2+ transients in narrow regions of cytosol between the secretory granules and plasma membrane that can be less than 0.5-microns wide. Moreover, these Ca2+ increases can be seen to coincide with the swelling of the secretory granules that follows exocytotic fusion. PMID:1730775

Different Topological Quantum States in Ternary Zintl compounds: BaCaX (X = Si, Ge, Sn and Pb)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lin-Lin; Kaminski, Adam; Canfield, Paul C.

Topological quantum states require stringent combination of crystal symmetry and spin–orbit coupling (SOC) strength. Here in this paper, we report that the ternary Zintl compound series BaCaX (X = Si, Ge, Sn and Pb, Group IV) in the same crystal structure having eight valence electrons per formula unit can host two different topological quantum phases, controlled by atomic size and SOC strength. BaCaSi is a nodal-line semimetal (NLSM) with band inversion protected by mirror symmetry and hosts a strong topological insulator (TI) state when SOC is turned on, thus, a NLSM-TI phase. Moving to larger atomic sizes and heavier atoms,more » BaCaGe and BaCaSn are normal insulators (NIs); then, with the strongest SOC in BaCaPb, a different band inversion is induced, giving a strong TI phase without the need of NLSM. Thus, we also predict two types of topological transitions in a phase diagram for BaCaX: (1) NLSM-TI to NI, then to TI by tuning atomic size and SOC strength via alloying, and (2) NI or TI to NLSM-TI via pressure.« less

Different Topological Quantum States in Ternary Zintl compounds: BaCaX (X = Si, Ge, Sn and Pb)

DOE PAGES

Wang, Lin-Lin; Kaminski, Adam; Canfield, Paul C.; ...

2017-12-14

Topological quantum states require stringent combination of crystal symmetry and spin–orbit coupling (SOC) strength. Here in this paper, we report that the ternary Zintl compound series BaCaX (X = Si, Ge, Sn and Pb, Group IV) in the same crystal structure having eight valence electrons per formula unit can host two different topological quantum phases, controlled by atomic size and SOC strength. BaCaSi is a nodal-line semimetal (NLSM) with band inversion protected by mirror symmetry and hosts a strong topological insulator (TI) state when SOC is turned on, thus, a NLSM-TI phase. Moving to larger atomic sizes and heavier atoms,more » BaCaGe and BaCaSn are normal insulators (NIs); then, with the strongest SOC in BaCaPb, a different band inversion is induced, giving a strong TI phase without the need of NLSM. Thus, we also predict two types of topological transitions in a phase diagram for BaCaX: (1) NLSM-TI to NI, then to TI by tuning atomic size and SOC strength via alloying, and (2) NI or TI to NLSM-TI via pressure.« less

Multiple Emplacement and Exhumation History of the Late Mesozoic Dayunshan-Mufushan Batholith in Southeast China and Its Tectonic Significance: 1. Structural Analysis and Geochronological Constraints

NASA Astrophysics Data System (ADS)

Ji, Wenbin; Faure, Michel; Lin, Wei; Chen, Yan; Chu, Yang; Xue, Zhenhua

2018-01-01

The South China Block (SCB) experienced a polyphase reworking by the Phanerozoic tectonothermal events. To better understand its Late Mesozoic tectonics, an integrated multidisciplinary investigation has been conducted on the Dayunshan-Mufushan composite batholith in the north-central SCB. This batholith consists of two major intrusions that recorded distinct emplacement features. According to our structural analysis, two deformation events in relation to batholith emplacement and subsequent exhumation are identified. The early one (D1) was observed mostly at the southern border of the batholith, characterized by a top-to-the-SW ductile shearing in the early-stage intrusion and along its contact zone. This deformation, chiefly associated with the pluton emplacement at ca. 150 Ma, was probably assisted by farfield compression from the northern Yangtze foreland belt. The second but main event (D2) involved two phases: (1) ductile shearing (D2a) prominently expressed along the Dayunshan detachment fault at the western border of the batholith where the syntectonic late-stage intrusion and minor metasedimentary basement in the footwall suffered mylonitization with top-to-the-NW kinematics; and (2) subsequent brittle faulting (D2b) further exhumed the entire batholith that behaved as rift shoulder with half-graben basins developed on its both sides. Geochronological constraints show that the crustal ductile extension occurred during 132-95 Ma. Such a Cretaceous NW-SE extensional tectonic regime, as indicated by the D2 event, has been recognized in a vast area of East Asia. This tectonism was responsible not only for the destruction of the North China craton but also for the formation of the so-called "southeast China basin and range tectonics."

Tectonic Inversion Along the Algerian and Ligurian Margins: On the Insight Provided By Latest Seismic Processing Techniques Applied to Recent and Vintage 2D Offshore Multichannel Seismic Data

NASA Astrophysics Data System (ADS)

Schenini, L.; Beslier, M. O.; Sage, F.; Badji, R.; Galibert, P. Y.; Lepretre, A.; Dessa, J. X.; Aidi, C.; Watremez, L.

2014-12-01

Recent studies on the Algerian and the North-Ligurian margins in the Western Mediterranean have evidenced inversion-related superficial structures, such as folds and asymmetric sedimentary perched basins whose geometry hints at deep compressive structures dipping towards the continent. Deep seismic imaging of these margins is difficult due to steep slope and superficial multiples, and, in the Mediterranean context, to the highly diffractive Messinian evaporitic series in the basin. During the Algerian-French SPIRAL survey (2009, R/V Atalante), 2D marine multi-channel seismic (MCS) reflection data were collected along the Algerian Margin using a 4.5 km, 360 channel digital streamer and a 3040 cu. in. air-gun array. An advanced processing workflow has been laid out using Geocluster CGG software, which includes noise attenuation, 2D SRME multiple attenuation, surface consistent deconvolution, Kirchhoff pre-stack time migration. This processing produces satisfactory seismic images of the whole sedimentary cover, and of southward dipping reflectors in the acoustic basement along the central part of the margin offshore Great Kabylia, that are interpreted as inversion-related blind thrusts as part of flat-ramp systems. We applied this successful processing workflow to old 2D marine MCS data acquired on the North-Ligurian Margin (Malis survey, 1995, R/V Le Nadir), using a 2.5 km, 96 channel streamer and a 1140 cu. in. air-gun array. Particular attention was paid to multiple attenuation in adapting our workflow. The resulting reprocessed seismic images, interpreted with a coincident velocity model obtained by wide-angle data tomography, provide (1) enhanced imaging of the sedimentary cover down to the top of the acoustic basement, including the base of the Messinian evaporites and the sub-salt Miocene series, which appear to be tectonized as far as in the mid-basin, and (2) new evidence of deep crustal structures in the margin which the initial processing had failed to reveal.

Fault kinematics and localised inversion within the Troms-Finnmark Fault Complex, SW Barents Sea

NASA Astrophysics Data System (ADS)

Zervas, I.; Omosanya, K. O.; Lippard, S. J.; Johansen, S. E.

2018-04-01

The areas bounding the Troms-Finnmark Fault Complex are affected by complex tectonic evolution. In this work, the history of fault growth, reactivation, and inversion of major faults in the Troms-Finnmark Fault Complex and the Ringvassøy Loppa Fault Complex is interpreted from three-dimensional seismic data, structural maps and fault displacement plots. Our results reveal eight normal faults bounding rotated fault blocks in the Troms-Finnmark Fault Complex. Both the throw-depth and displacement-distance plots show that the faults exhibit complex configurations of lateral and vertical segmentation with varied profiles. Some of the faults were reactivated by dip-linkages during the Late Jurassic and exhibit polycyclic fault growth, including radial, syn-sedimentary, and hybrid propagation. Localised positive inversion is the main mechanism of fault reactivation occurring at the Troms-Finnmark Fault Complex. The observed structural styles include folds associated with extensional faults, folded growth wedges and inverted depocentres. Localised inversion was intermittent with rifting during the Middle Jurassic-Early Cretaceous at the boundaries of the Troms-Finnmark Fault Complex to the Finnmark Platform. Additionally, tectonic inversion was more intense at the boundaries of the two fault complexes, affecting Middle Triassic to Early Cretaceous strata. Our study shows that localised folding is either a product of compressional forces or of lateral movements in the Troms-Finnmark Fault Complex. Regional stresses due to the uplift in the Loppa High and halokinesis in the Tromsø Basin are likely additional causes of inversion in the Troms-Finnmark Fault Complex.

Inheritance vs ongoing evolution of the passive margin lithosphere in the southeastern United States: A comparison of <50Ma tectonism with tomographically imaged lithospheric structures.

NASA Astrophysics Data System (ADS)

Wagner, L. S.; Fischer, K. M.; Hawman, R. B.; Hopper, E.; Howell, D.

2017-12-01

The southeastern United States is an archetypical passive margin, and yet significant evidence exists that this region, separated from the nearest plate boundary by thousands of kilometers and over 170 Ma, has experienced significant tectonism since the Eocene. This tectonism includes volcanism, uplift/deformation, and ongoing seismicity such as the 2011 Mw = 5.8 Mineral, VA earthquake and the 1886 M=7 Charleston, SC event. For each of these examples, numerous theories exist on their respective causes. However, there are two common themes that span all of these types of events: first, their proximity to regional terrane boundaries whose inherited structures could play a role; second, the nature of the mantle lithosphere underlying them. We present a recently completed inversion of seismic Rayleigh waves for the shear wave velocity structure of the uppermost 150 - 200 km beneath the southeastern United States. This inversion includes not only EarthScope Transportable Array data, but also the data from the 85 broadband stations installed as part of the Flex Array SouthEastern Suture of the Appalachian Mountains Experiment (SESAME). We find some evidence for structures inherited from previous episodes of rifting, accretion, and orogenesis. However, we also find several examples of mantle lithospheric structures that spatially correlate strongly with Eocene to recent tectonic activity, but do not correlate to any known inherited geometries. These examples include a small but pronounced sub-crustal low velocity anomaly beneath the Eocene volcanoes in western Virginia and eastern West Virginia, as well as evidence for mantle delamination beneath the Cape Fear Arch and uplifted portions of the Orangeburg Escarpment. We will discuss these, along with instances of recent tectonism in our study area that do not bear any obvious relationship to lithospheric structures, in order to shed light on the causes of ongoing tectonic activity in this supposedly "passive" margin setting.

Post-rift deformation of the Red Sea Arabian margin

NASA Astrophysics Data System (ADS)

Zanoni, Davide; Schettino, Antonio; Pierantoni, Pietro Paolo; Rasul, Najeeb

2017-04-01

Starting from the Oligocene, the Red Sea rift nucleated within the composite Neoproterozoic Arabian-Nubian shield. After about 30 Ma-long history of continental lithosphere thinning and magmatism, the first pulse of oceanic spreading occurred at around 4.6 Ma at the triple junction of Africa, Arabia, and Danakil plate boundaries and propagated southward separating Danakil and Arabia plates. Ocean floor spreading between Arabia and Africa started later, at about 3 Ma and propagated northward (Schettino et al., 2016). Nowadays the northern part of the Red Sea is characterised by isolated oceanic deeps or a thinned continental lithosphere. Here we investigate the deformation of thinned continental margins that develops as a consequence of the continental lithosphere break-up induced by the progressive oceanisation. This deformation consists of a system of transcurrent and reverse faults that accommodate the anelastic relaxation of the extended margins. Inversion and shortening tectonics along the rifted margins as a consequence of the formation of a new segment of ocean ridge was already documented in the Atlantic margin of North America (e.g. Schlische et al. 2003). We present preliminary structural data obtained along the north-central portion of the Arabian rifted margin of the Red Sea. We explored NE-SW trending lineaments within the Arabian margin that are the inland continuation of transform boundaries between segments of the oceanic ridge. We found brittle fault zones whose kinematics is consistent with a post-rift inversion. Along the southernmost transcurrent fault (Ad Damm fault) of the central portion of the Red Sea we found evidence of dextral movement. Along the northernmost transcurrent fault, which intersects the Harrat Lunayyir, structures indicate dextral movement. At the inland termination of this fault the evidence of dextral movement are weaker and NW-SE trending reverse faults outcrop. Between these two faults we found other dextral transcurrent systems that locally are associated with metre-thick reverse fault zones. Along the analysed faults there is evidence of tectonic reworking. Relict kinematic indicators or the sense of asymmetry of sigmoidal Miocene dykes may suggest that a former sinistral movement was locally accommodated by these faults. This evidence of inversion of strike-slip movement associated with reverse structures, mostly found at the inland endings of these lineaments, suggests an inversion tectonics that could be related to the progressive and recent oceanisation of rift segments. Schettino A., Macchiavelli C., Pierantoni P.P., Zanoni D. & Rasul N. 2016. Recent kinematics of the tectonic plates surrounding the Red Sea and Gulf of Aden. Geophysical Journal International, 207, 457-480. Schlische R.W., Withjack M.O. & Olsen P.E., 2003. Relative timing of CAMP, rifting, continental breakup, and basin inversion: tectonic significance, in The Central Atlantic Magmatic Province: Insights from Fragments of Pangea, eds Hames W., Mchone J.G., Renne P. & Ruppel C., American Geophysical Union, 33-59.

Magnetic fabrics in tectonically inverted sedimentary basins: a review

NASA Astrophysics Data System (ADS)

García-Lasanta, Cristina; Román-Berdiel, Teresa; Casas-Sainz, Antonio; Oliva-Urcia, Belén; Soto, Ruth; Izquierdo-Llavall, Esther

2017-04-01

Magnetic fabric studies in sedimentary rocks were firstly focused on strongly deformed tectonic contexts, such as fold-and-thrust belts. As measurement techniques were improved by the introduction of high-resolution equipments (e.g. KLY3-S and more recent Kappabridge susceptometers from AGICO Inc., Czech Republic), more complex tectonic contexts could be subjected to anisotropy of magnetic susceptibility (AMS) analyses in order to describe the relationship between tectonic conditions and the orientation and shape of the resultant magnetic ellipsoids. One of the most common complex tectonic frames involving deformed sedimentary rocks are inverted extensional basins. In the last decade, multiple AMS studies revealed that the magnetic fabric associated with the extensional stage (i.e. a primary magnetic fabric) can be preserved despite the occurrence of subsequent deformational processes. In these cases, magnetic fabrics may provide valuable information about the geometry and kinematics of the extensional episode (i.e. magnetic ellipsoids with their minimum susceptibility axis oriented perpendicular to the deposit plane and magnetic lineation oriented parallel to the extension direction). On the other hand, several of these studies have also determined how the subsequent compressional stage can modify the primary extensional fabric in some cases, particularly in areas subjected to more intense deformation (with development of compression-related cleavage). In this contribution we present a compilation of AMS studies developed in sedimentary basins that underwent different degree of tectonic inversion during their history, in order to describe the relationship of this degree of deformation and the degree of imprint that tectonic conditions have in the previous magnetic ellipsoid (primary extension-related geometry). The inverted basins included in this synthesis are located in the Iberian Peninsula and show: i) weak deformation (W Castilian Branch and Maestrazgo basin, Iberian Range); ii) transport along the hangingwall of thrusts with very slight internal deformation (Organyà basin, Central Pyrenees); iii) record of incipient compressive strain and foliation development (Cabuerniga basin, Basque-Cantabrian Basin; Lusitanian basin, W Portugal); iv) complete inversion associated with a remarkable transport along the hangingwall of thrusts and relatively large internal deformation (Cameros basin, Iberian Range); and v) major folding and flattening linked to foliation (Mauléon basin, Northern Pyrenees; Nogueres unit, Pyrenean Axial Zone).

Chromospheric heating during flux emergence in the solar atmosphere

NASA Astrophysics Data System (ADS)

Leenaarts, Jorrit; de la Cruz Rodríguez, Jaime; Danilovic, Sanja; Scharmer, Göran; Carlsson, Mats

2018-04-01

Context. The radiative losses in the solar chromosphere vary from 4 kW m-2 in the quiet Sun, to 20 kW m-2 in active regions. The mechanisms that transport non-thermal energy to and deposit it in the chromosphere are still not understood. Aim. We aim to investigate the atmospheric structure and heating of the solar chromosphere in an emerging flux region. Methods: We have used observations taken with the CHROMIS and CRISP instruments on the Swedish 1-m Solar Telescope in the Ca II K , Ca II 854.2 nm, Hα, and Fe I 630.1 nm and 630.2 nm lines. We analysed the various line profiles and in addition perform multi-line, multi-species, non-local thermodynamic equilibrium (non-LTE) inversions to estimate the spatial and temporal variation of the chromospheric structure. Results: We investigate which spectral features of Ca II K contribute to the frequency-integrated Ca II K brightness, which we use as a tracer of chromospheric radiative losses. The majority of the radiative losses are not associated with localised high-Ca II K-brightness events, but instead with a more gentle, spatially extended, and persistent heating. The frequency-integrated Ca II K brightness correlates strongly with the total linear polarization in the Ca II 854.2 nm, while the Ca II K profile shapes indicate that the bulk of the radiative losses occur in the lower chromosphere. Non-LTE inversions indicate a transition from heating concentrated around photospheric magnetic elements below log τ500 = -3 to a more space-filling and time-persistent heating above log τ500 = -4. The inferred gas temperature at log τ500 = -3.8 correlates strongly with the total linear polarization in the Ca II 854.2 nm line, suggesting that that the heating rate correlates with the strength of the horizontal magnetic field in the low chromosphere. Movies attached to Figs. 1 and 4 are available at http://https://www.aanda.org/

Mineralogy and geochemistry of the Mahi River sediments in tectonically active western India: Implications for Deccan large igneous province source, weathering and mobility of elements in a semi-arid climate

NASA Astrophysics Data System (ADS)

Sharma, Anupam; Sensarma, Sarajit; Kumar, Kamlesh; Khanna, P. P.; Saini, N. K.

2013-03-01

Large igneous provinces (LIPs) hosting mafic rocks over million km2 are likely to influence global sediment production and distribution and help in resolving discrepancies in upper continental crust (UCC) compositions. This work focuses on the texture, mineralogy, and compositions including REE of fine sand/silt deposited by a small to medium-sized river, the Mahi River (about 600 km) in a tectonically active, semi-arid region draining the Deccan Traps in western India, one of the largest LIPs in the world. The results are also applied to a sedimentary rock of fluvial origin (Siwalik mudstone/siltstone) to ascertain the source characteristics of this alluvium and evaluate comparative element (K, Ba, Sr, Na, Ca and Mg) mobility. The Mahi sediments are lithiarenite, mostly composed of quartz and basalt fragments with lesser pyroxene, biotite, feldspar, calcite and clay minerals (smectite ± illite). The Mahi sediments have higher FeOt (⩽10.9 wt.%), TiO2 (⩽2.41 wt.%), Al2O3 (⩽15.2 wt.%), Cr (⩽737 ppm), Co (⩽36 ppm), Cu (⩽107 ppm) than the UCC and PAAS; Ni (⩽54 ppm) higher than the UCC (33.5 ppm), but similar to PAAS (60 ppm). The low CIA (37-59) values and presence of basalt fragments and smectite in the samples suggest incipient weathering in the semi-arid Mahi catchment. In agreement with the mineralogy, the UCC-normalized LREE depleted patterns (LREE/HREE < 1) in the Mahi sediments confirm Deccan basalt contributions from the provenance with about 70-75% basalts and 25-30% Archean biotite-rich granitoids. The mafic contribution, in addition to the UCC, is important for the Siwalik rocks too. Similarly limited depletion of Ba, K and Ca (Ba ⩾ K > Ca) in weathering-limited Mahi (aver CIA 47.5) and transport-limited Siwalik (aver CIA 69) systems indicate their climate insensitivity. At the same time, more Ba depletion than Ca is new for the Deccan Traps River. Decoupling of Ca and Sr, however, could be mineralogy controlled.

A PILOT SEARCH FOR EVIDENCE OF EXTRASOLAR EARTH-ANALOG PLATE TECTONICS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jura, M.; Klein, B.; Xu, S.

Relative to calcium, both strontium and barium are markedly enriched in Earth's continental crust compared to the basaltic crusts of other differentiated rocky bodies within the solar system. Here, we both re-examine available archived Keck spectra to place upper bounds on n(Ba)/n(Ca) and revisit published results for n(Sr)/n(Ca) in two white dwarfs that have accreted rocky planetesimals. We find that at most only a small fraction of the pollution is from crustal material that has experienced the distinctive elemental enhancements induced by Earth-analog plate tectonics. In view of the intense theoretical interest in the physical structure of extrasolar rocky planets,more » this search should be extended to additional targets.« less

Polar Oxides without Inversion Symmetry through Vacancy and Chemical Order.

PubMed

Young, Joshua; Moon, Eun Ju; Mukherjee, Debangshu; Stone, Greg; Gopalan, Venkatraman; Alem, Nasim; May, Steven J; Rondinelli, James M

2017-02-22

One synthetic modality for materials discovery proceeds by forming mixtures of two or more compounds. In transition metal oxides (TMOs), chemical substitution often obeys Vegard's principle, and the resulting structure and properties of the derived phase follow from its components. A change in the assembly of the components into a digital nanostructure, however, can stabilize new polymorphs and properties not observed in the constituents. Here we formulate and demonstrate a crystal-chemistry design approach for realizing digital TMOs without inversion symmetry by combining two centrosymmetric compounds, utilizing periodic anion-vacancy order to generate multiple polyhedra that together with cation order produce a polar structure. We next apply this strategy to two brownmillerite-structured TMOs known to display centrosymmetric crystal structures in their bulk, Ca 2 Fe 2 O 5 and Sr 2 Fe 2 O 5 . We then realize epitaxial (SrFeO 2.5 ) 1 /(CaFeO 2.5 ) 1 thin film superlattices possessing both anion-vacancy order and Sr and Ca chemical order at the subnanometer scale, confirmed through synchrotron-based diffraction and aberration corrected electron microscopy. Through a detailed symmetry analysis and density functional theory calculations, we show that A-site cation ordering lifts inversion symmetry in the superlattice and produces a polar compound. Our results demonstrate how control of anion and cation order at the nanoscale can be utilized to produce acentric structures markedly different than their constituents and open a path toward novel structure-based property design.

Phanerozoic polyphase orogenies recorded in the northeastern Okcheon Belt, Korea from SHRIMP U-Pb detrital zircon and K-Ar illite geochronologies

NASA Astrophysics Data System (ADS)

Jang, Yirang; Kwon, Sanghoon; Song, Yungoo; Kim, Sung Won; Kwon, Yi Kyun; Yi, Keewook

2018-05-01

We present the SHRIMP U-Pb detrital zircon and K-Ar illite 1Md/1M and 2M1 ages, suggesting new insight into the Phanerozoic polyphase orogenies preserved in the northeastern Okcheon Belt, Korea since the initial basin formation during Neoproterozoic rifting through several successive contractional orogens. The U-Pb detrital zircon ages from the Early Paleozoic strata of the Taebaeksan Zone suggest a Cambrian maximum deposition age, and are supported by trilobite and conodont biostratigraphy. Although the age spectra from two sedimentary groups, the Yeongwol and Taebaek Groups, show similar continuous distributions from the Late Paleoproterozoic to Early Paleozoic ages, a Grenville-age hiatus (1.3-0.9 Ga) in the continuous stratigraphic sequence from the Taebaek Group suggests the existence of different peripheral clastic sources along rifted continental margin(s). In addition, we present the K-Ar illite 1Md/1M ages of the fault gouges, which confirm fault formation/reactivation during the Late Cretaceous to Early Paleogene (ca. 82-62 Ma) and the Early Miocene (ca. 20-18 Ma). The 2M1 illite ages, at least those younger than the host rock ages, provide episodes of deformation, metamorphism and hydrothermal effects related to the tectonic events during the Devonian (ca.410 Ma) and Permo-Triassic (ca. 285-240 Ma). These results indicate that the northeastern Okcheon Belt experienced polyphase orogenic events, namely the Okcheon (Middle Paleozoic), Songrim (Late Paleozoic to Early Mesozoic), Daebo (Middle Mesozoic) and Bulguksa (Late Mesozoic to Early Cenozoic) Orogenies, reflecting the Phanerozoic tectonic evolution of the Korean Peninsula along the East Asian continental margin.

The Rae craton of Laurentia/Nuna: a tectonically unique entity providing critical insights into the concept of Precambrian supercontinental cyclicity

NASA Astrophysics Data System (ADS)

Bethune, K. M.

2015-12-01

Forming the nucleus of Laurentia/Nuna, the Rae craton contains rocks and structures ranging from Paleo/Mesoarchean to Mesoproterozoic in age and has long been known for a high degree of tectonic complexity. Recent work strongly supports the notion that the Rae developed independently from the Hearne; however, while the Hearne appears to have been affiliated with the Superior craton and related blocks of 'Superia', the genealogy of Rae is far less clear. A diagnostic feature of the Rae, setting it apart from both Hearne and Slave, is the high degree of late Neoarchean to early Paleoproterozoic reworking. Indeed, following a widespread 2.62-2.58 Ga granite bloom, the margins of Rae were subjected to seemingly continuous tectonism, with 2.55-2.50 Ga MacQuoid orogenesis in the east superseded by 2.50 to 2.28 Ga Arrowsmith orogenesis in the west. A recent wide-ranging survey of Hf isotopic ratios in detrital and magmatic zircons across Rae has demonstrated significant juvenile, subduction-related crustal production in this period. Following break-up at ca. 2.1 Ga, the Rae later became a tectonic aggregation point as the western and eastern margins transitioned back to convergent plate boundaries (Thelon-Taltson and Snowbird orogens) marking onset of the 2.0-1.8 Ga assembly of Nuna. The distinctive features of Rae, including orogenic imprints of MacQuoid and Arrowsmith vintage have now been identified in about two dozen cratonic blocks world-wide, substantiating the idea that the Rae cratonic family spawned from an independent earliest Paleoproterozoic landmass before its incorportation in Nuna. While critical tests remain to be made, including more reliable ground-truthing of proposed global correlations, these relationships strongly support the notion of supercontinental cyclicity in the Precambrian, including the Archean. They also challenge the idea of a globally quiescent period in the early Paleoproterozoic (2.45-2.2 Ga) in which plate tectonics slowed or shut down.

Structure and structural evolution of the Rechnitz window and adjacent units, Eastern Alps: changing Neogene extension directions due to motion around a foreland promontory

NASA Astrophysics Data System (ADS)

Neubauer, Franz; Cao, Shuyun

2013-04-01

The Rechnitz window is part of Penninic window group exposed along the South Burgenland basement high within the large Neogene Pannonian basin, which is formed by changing the extension directions during the motion of the Alcapa block around the Bohemian foreland promontory. Based on new data of the structural history of Penninic units, its burial and exhumation is proposed during eastward and northeastward motion around the Bohemian foreland promontory. Two tectonic units within the Rechnitz window are distinguished, the Schlaining unit with ophiolites, which show a Paleogene history of subduction (deformation stage D1), and the Köszeg unit with distal continental margin successions indicated by their richness of continent-derived clastic material. Previous fossil findings indicate a persistence of sedimentation until early Late Cretaceous. Both units were subducted during Paleogene and suffered blueschist metamorphism. The age of ophiolite obduction onto the Köszeg unit must be between latest Paleocene and earliest Miocene associated with peak temperature conditions (deformation stage D2, likely at 22 Ma). A new 40Ar/39Ar white mica age shows a plateau-type pattern at 22.3 ± 0.2 Ma and a subsequent thermal event of Ar loss at 19.2 ± 0.5 Ma. Exhumation and extension of buried Penninic rocks were facilitated by a sequence of normal faults and the change of the motion direction from northeastward to eastward motion (D3 and D4a). In present-day coordinates, the initial stage of faulting along a major ductile low-angle normal fault was directed northeastward at ca. 19 Ma. In the subsequent stage (Early Miocene), extension resulted in a ca. eastward prograding rolling hinge, which separates the Rechnitz window from Danube basin located in the east (D4a). Gently W-dipping thrust faults indicate ca. WSW-ENE shortening and also resulted in ca. N-S trending E-vergent folds occur in lower sectors of the Köszeg unit (deformation stage D4b). Finally, small Late Miocene to Early Quaternary alkali-basaltic volcanic centers with lava flows and tuffs spread in a regular sequence over 95 km from Pauliberg/Oberpullendorf (ca. 11 Ma) located in the NE over Güssing (ca. 5 Ma), and finally to the SW (e.g. Klöch, 2.6 to 1.6 Ma). We interpret this volcanism to have resulted from thinning of the lithosphere in the Pannonian basin over a hot-spot with the Alcapa plate moving from SW to the NE between 11 and ca. 2 Ma. Subsequent ca. ESE-trending dextral and ca. NNW-trending sinistral strike-slip faults indicate NW-SE strike-slip compression (D5a), which progressively shifted to N-S strike-slip compression facilitated by NNE-trending sinistral strike-slip faults and NNW-trending dextral strike-slip faults (D5b). This event (D5b) likely also resulted in gentle high-wavelength crustal-scale folding and is interpreted to result from Pliocene inversion of the entire Pannonian-Carpathian basin system.

Electrical resistivity structure of the Great Slave Lake shear zone, northwest Canada: implications for tectonic history

NASA Astrophysics Data System (ADS)

Yin, Yaotian; Unsworth, Martyn; Liddell, Mitch; Pana, Dinu; Craven, James A.

2014-10-01

Three magnetotelluric (MT) profiles in northwestern Canada cross the central and western segments of Great Slave Lake shear zone (GSLsz), a continental scale strike-slip structure active during the Slave-Rae collision in the Proterozoic. Dimensionality analysis indicates that (i) the resistivity structure is approximately 2-D with a geoelectric strike direction close to the dominant geological strike of N45°E and that (ii) electrical anisotropy may be present in the crust beneath the two southernmost profiles. Isotropic and anisotropic 2-D inversion and isotropic 3-D inversions show different resistivity structures on different segments of the shear zone. The GSLsz is imaged as a high resistivity zone (>5000 Ω m) that is at least 20 km wide and extends to a depth of at least 50 km on the northern profile. On the southern two profiles, the resistive zone is confined to the upper crust and pierces an east-dipping crustal conductor. Inversions show that this dipping conductor may be anisotropic, likely caused by conductive materials filling a network of fractures with a preferred spatial orientation. These conductive regions would have been disrupted by strike-slip, ductile deformation on the GSLsz that formed granulite to greenschist facies mylonite belts. The pre-dominantly granulite facies mylonites are resistive and explain why the GSLsz appears as a resistive structure piercing the east-dipping anisotropic layer. The absence of a dipping anisotropic/conductive layer on the northern MT profile, located on the central segment of the GSLsz, is consistent with the lack of subduction at this location as predicted by geological and tectonic models.

Using Vertical Electrical Soundings for Characterizing Hydrogeological and Tectonic Settings in Deir El-Adas Area, Yarmouk Basin, Syria

NASA Astrophysics Data System (ADS)

Al-Fares, Walid

2016-06-01

The present study is aimed at characterizing the subsurface geological and tectonic structure in Deir El-Adas area, by using Vertical Electrical Sounding survey (VES) and hydrogeological investigations, in order to determine the causes of the failure for the majority of the wells drilled in the area. The survey data was treated in three different approaches including direct VES inversion, pseudo-2D method and horizontal profiling, in order to maximize the reliability of the data interpretation. The results revealed the presence of a local faulted anticline structure at the top of the Paleogene formation, underneath the basaltic outcrops where Deir El-Adas village is situated. The appearance of this subsurface anticline structure has complicated the local hydro-geological situation, and most likely led to limitation of the groundwater recharge in the area. Moreover, the performed piezometric and discharge maps indicated the presence of a notable groundwater watershed, in addition to feeble water productivity of the wells drilled adjacent to Deir El-Adas, mostly related to the subsurface geological and tectonic settings in the area.

A Bootstrap-Based Probabilistic Optimization Method to Explore and Efficiently Converge in Solution Spaces of Earthquake Source Parameter Estimation Problems: Application to Volcanic and Tectonic Earthquakes

NASA Astrophysics Data System (ADS)

Dahm, T.; Heimann, S.; Isken, M.; Vasyura-Bathke, H.; Kühn, D.; Sudhaus, H.; Kriegerowski, M.; Daout, S.; Steinberg, A.; Cesca, S.

2017-12-01

Seismic source and moment tensor waveform inversion is often ill-posed or non-unique if station coverage is poor or signals are weak. Therefore, the interpretation of moment tensors can become difficult, if not the full model space is explored, including all its trade-offs and uncertainties. This is especially true for non-double couple components of weak or shallow earthquakes, as for instance found in volcanic, geothermal or mining environments.We developed a bootstrap-based probabilistic optimization scheme (Grond), which is based on pre-calculated Greens function full waveform databases (e.g. fomosto tool, doi.org/10.5880/GFZ.2.1.2017.001). Grond is able to efficiently explore the full model space, the trade-offs and the uncertainties of source parameters. The program is highly flexible with respect to the adaption to specific problems, the design of objective functions, and the diversity of empirical datasets.It uses an integrated, robust waveform data processing based on a newly developed Python toolbox for seismology (Pyrocko, see Heimann et al., 2017, http://doi.org/10.5880/GFZ.2.1.2017.001), and allows for visual inspection of many aspects of the optimization problem. Grond has been applied to the CMT moment tensor inversion using W-phases, to nuclear explosions in Korea, to meteorite atmospheric explosions, to volcano-tectonic events during caldera collapse and to intra-plate volcanic and tectonic crustal events.Grond can be used to optimize simultaneously seismological waveforms, amplitude spectra and static displacements of geodetic data as InSAR and GPS (e.g. KITE, Isken et al., 2017, http://doi.org/10.5880/GFZ.2.1.2017.002). We present examples of Grond optimizations to demonstrate the advantage of a full exploration of source parameter uncertainties for interpretation.

Counter-intuitive features of the dynamic topography unveiled by tectonically realistic 3D numerical models of mantle-lithosphere interactions

NASA Astrophysics Data System (ADS)

Burov, Evgueni; Gerya, Taras

2013-04-01

It has been long assumed that the dynamic topography associated with mantle-lithosphere interactions should be characterized by long-wavelength features (> 1000 km) correlating with morphology of mantle flow and expanding beyond the scale of tectonic processes. For example, debates on the existence of mantle plumes largely originate from interpretations of expected signatures of plume-induced topography that are compared to the predictions of analytical and numerical models of plume- or mantle-lithosphere interactions (MLI). Yet, most of the large-scale models treat the lithosphere as a homogeneous stagnant layer. We show that in continents, the dynamic topography is strongly affected by rheological properties and layered structure of the lithosphere. For that we reconcile mantle- and tectonic-scale models by introducing a tectonically realistic continental plate model in 3D large-scale plume-mantle-lithosphere interaction context. This model accounts for stratified structure of continental lithosphere, ductile and frictional (Mohr-Coulomb) plastic properties and thermodynamically consistent density variations. The experiments reveal a number of important differences from the predictions of the conventional models. In particular, plate bending, mechanical decoupling of crustal and mantle layers and intra-plate tension-compression instabilities result in transient topographic signatures such as alternating small-scale surface features that could be misinterpreted in terms of regional tectonics. Actually thick ductile lower crustal layer absorbs most of the "direct" dynamic topography and the features produced at surface are mostly controlled by the mechanical instabilities in the upper and intermediate crustal layers produced by MLI-induced shear and bending at Moho and LAB. Moreover, the 3D models predict anisotropic response of the lithosphere even in case of isotropic solicitations by axisymmetric mantle upwellings such as plumes. In particular, in presence of small (i.e. insufficient to produce solely any significant deformation) uniaxial extensional tectonic stress field, the plume-produced surface and LAB features have anisotropic linear shapes perpendicular to the far-field tectonic forces, typical for continental rifts. Compressional field results in singular sub-linear folds above the plume head, perpendicular to the direction of compression. Small bi-axial tectonic stress fields (compression in one direction and extension in the orthogonal direction) result in oblique, almost linear segmented normal or inverse faults with strike-slip components (or visa verse , strike-slip faults with normal or inverse components)

Tectono-climatic implications of Eocene Paratethys regression in the Tajik basin of central Asia

NASA Astrophysics Data System (ADS)

Carrapa, Barbara; DeCelles, Peter G.; Wang, Xin; Clementz, Mark T.; Mancin, Nicoletta; Stoica, Marius; Kraatz, Brian; Meng, Jin; Abdulov, Sherzod; Chen, Fahu

2015-08-01

Plate tectonics and eustatic sea-level changes have fundamental effects on paleoenvironmental conditions and bio-ecological changes. The Paratethys Sea was a large marine seaway that connected the Mediterranean Neotethys Ocean with Central Asia during early Cenozoic time. Withdrawal of the Paratethys from central Asia impacted the distribution and composition of terrestrial faunas in the region and has been largely associated with changes in global sea level and climate such as cooling associated with the Eocene/Oligocene transition (EOT). Whereas the regression has been dated in the Tarim basin (China), the pattern and timing of regression in the Tajik basin, 400 km to the west, remain unresolved, precluding a test of current paleogeographic models. Here we date the Paratethys regression in Tajikistan at ca. 39 million years ago (Ma), which is several million years older than the EOT (at ca. 34 Ma) marking the greenhouse to icehouse climate transition of the Cenozoic. Our data also show a restricted, evaporitic marine environment since the middle-late Eocene and establishment of desert like environments after ca. 39 Ma. The overall stratigraphic record from the Tajik basin and southern Tien Shan points to deposition in a foreland basin setting by ca. 40 Ma in response to active tectonic growth of the Pamir-Tibet Mountains at the same time. Combined with the northwestward younging trend of the regression in the region, the Tajik basin record is consistent with northward growth of the Pamir and suggests significant tectonic control on Paratethys regression and paleoenvironmental changes in Central Asia.

A Nonlinear Inversion Approach to Map the Magnetic Basement: A Case Study from Central India Using Aeromagnetic Data

NASA Astrophysics Data System (ADS)

Kumar, R.; Bansal, A. R.; Anand, S. P.; Rao, V. K.; Singh, U. K.

2016-12-01

The central India region is having complex geology covering various geological units e.g., Precambrian Bastar Craton (including Proterozoic Chhattisgarh Basin, granitic intrusions etc.) and Eastern Ghat Mobile Belt, Gondwana Godavari and Mahanadi Grabens, Late Cretaceous Deccan Traps etc. The central India is well covered by reconnaissance scale aeromagnetic data. We analyzed this data for mapping the basement by dividing into143 overlapping blocks of 100×100km using least square nonlinear inversion method for fractal distribution of sources. The scaling exponents and depth values are optimized using grid search method. We interpreted estimated depths of anomalous sources as magnetic basement and shallow anomalous magnetic sources. The shallow magnetic anomalies are found to vary from 1 to 3km whereas magnetic basement depths are found to vary from 2km to 7km. The shallowest basement depth of 2km found corresponding to Kanker granites a part of Bastar Craton whereas deepest basement depth of 7km is associated with Godavari Graben and south eastern part of Eastern Ghat Mobile Belts near the Parvatipuram Bobbili fault. The variation of magnetic basement, shallow depths and scaling exponent in the region indicate complex tectonic, heterogeneity and intrusive bodies at different depths which is due to different tectonic processes in the region. The detailed basement depth of central India is presented in this study.

Rifting, drifting, convergence and orogenesis: The sedimentary record of the Wernecke Supergroup on the Paleoproterozoic margin of northwestern Columbia

NASA Astrophysics Data System (ADS)

Furlanetto, F.; Thorkelson, D. J.; Rainbird, R.; Davis, B.; Gibson, D.; Marshall, D. D.

2015-12-01

The Wernecke Supergroup was deposited when the northwestern margin of Laurentia was undergoing major adjustments related to the assembly of the supercontinent Columbia (Nuna) in the late Paleoproterozoic. The succession was deposited between ca. 1663 and ca. 1620 Ma in two clastic to carbonate grand cycles. The detrital zircon population is bimodal, reflecting derivation from cratonic Laurentia. Basin shallowing at the end of the second grand cycle corresponds to a significant younging of detrital zircon populations. Specifically, the late Paleoproterozoic peak of zircon ages shifted from ca. 1900 Ma to ca. 1825 Ma, and the proportion of Archaean and early Paleoproterozoic zircon decreased. These shifts were caused by a change in drainage pattern in northern Laurentia during an early phase of the Forward orogeny, farther inland. The orogeny also led to inversion of the broadly correlative Hornby Bay Group. Zircon younger than 1.75 Ga is present throughout the sedimentary succession and may have originated from small igneous suites in northern Laurentia or larger magmatic arc terranes of the Yavapai and early Mazatzal orogenies in southern Laurentia. Eastern and southern Australia and the intervening Bonnetian arc may have contributed. The Wernecke Supergroup shares similar detrital zircon age and Nd isotope signatures with the Hornby Bay, Muskwa, Athabasca and Thelon successions of Canada; the Tarcoola Formation, Willyama Supergroup, and Isan Supergroup of Australia; and of the Dongchuan-Dahongshan-Hondo successions of South China. These similarities are compelling evidence for a shared depositional system in the late Paleoproterozoic. Western Columbia may have had a dynamic SWEAT-like configuration with Australia, East Antarctica and South China moving in a complex manner near the margin of western Laurentia. All of the continents except for South China underwent post-Wernecke tectonism during the Racklan, Forward, Olarian, Isan, Mazatzal and related orogenies, ca. 1.6-1.5 Ga.

A multidisciplinary study on the crustal architecture and tectonic evolution of the Biligiri Rangan Block, southern India: Implications for Neoarchean plate tectonics

NASA Astrophysics Data System (ADS)

Raveendran Thankamoni, Ratheesh Kumar

2017-04-01

Southern India is comprised of a collage of crustal blocks ranging in age from Archean to Neoproterozoic. Previous studies considered the Archean high-grade granulite terrain to the north of the Southern Granuilte Terrain (SGT) of southern India as the part of the Dharwar Craton and hence subdivided this craton into western, central and eastern provinces. This contribution presents my detailed examinations on the least studied Central Dharwar Province, comprising the Biligiri Rangan (BR) - Male Mahadeshwara (MM) Hills domain composed predominantly of charnockites. One of my recent study (Ratheesh-Kumar et al., 2016) for the first time provided necessary evidence for Neoarchean subduction-accretion-collision tectonic evolution of this domain as a separate crustal block which has been named as Biligiri Rangan Block (BRB) by using a multidisciplinary approach involving field investigation, petrography, mineral chemistry, thermodynamic modeling of metamorphic P-T evolution, and LA-ICPMS U-Pb and Lu-Hf analyses of zircons on representative rocks together with regional-scale crustal thickness model derived using isostatic gravimetric geophysical method. The important findings of this study are: (1) The BRB preserves the vestiges of a Mesoarchean primitive continental crust as indicated by the age (ca. 3207) and positive ɛHf value (+2.7) of quartzofeldspathic gneiss occurred in the central part of the block (2) The charnockites and associated mafic granulites and granites provide ages between ca. 2650 Ma and ca. 2498 Ma with large negative ɛHf values are suggestive of Neoarchean charnockitization and crustal remelting (3) New geochemical data of charnockites and mafic granulites from BRB are consistent with arc magmatic rocks generated through oceanic plate subduction (4) Delineation of a suture zone along the Kollegal structural lineament bounding the BRB and the Western Dharwar Craton surmised from the occurrences of quartzite-iron formation intercalations and also mafic-ultramafic lenses along this lineament with their evolution through a clockwise prograde and retrograde metamorphism in a subduction zone setting at a high-pressure of 18-19 kbar and temperature of ˜840°C (5) Spatial variation of crustal thickness data reveal high crustal thickness in the Biligiri Rangan and the Nilgiri Blocks, and are attributed to a more competently thickened crust resulted by the subduction and collision processes. Based on these results, this study proposes a new tectonic model for the evolution of the BRB that envisages eastward subduction of the Western Dharwar oceanic crust beneath the BRB along the Kollegal suture zone resulted in the arc magmatism during the Neoarchean. The relevance of this study relies on the fact that the proposed evolutionary model revises the existing debates on the tectonic framework and evolution of the Archean terranes of southern India.

Tectonic and sedimentary linkages between the Belt-Purcell basin and southwestern Laurentia during the Mesoproterozoic ca. 1.60-1.40 Ga

USGS Publications Warehouse

Jones, James V.; Dainel, Christohper G; Doe, Michael F

2015-01-01

Mesoproterozoic sedimentary basins in western North America provide key constraints on pre-Rodinia craton positions and interactions along the western rifted margin of Laurentia. One such basin, the Belt-Purcell basin, extends from southern Idaho into southern British Columbia and contains a >18-km-thick succession of siliciclastic sediment deposited ca. 1.47–1.40 Ga. The ca. 1.47–1.45 Ga lower part of the succession contains abundant distinctive non-Laurentian 1.61–1.50 Ga detrital zircon populations derived from exotic cratonic sources. Contemporaneous metasedimentary successions in the southwestern United States–the Trampas and Yankee Joe basins in Arizona and New Mexico–also contain abundant 1.61–1.50 Ga detrital zircons. Similarities in depositional age and distinctive non-Laurentian detrital zircon populations suggest that both the Belt-Purcell and southwestern successions record sedimentary and tectonic linkages between western Laurentia and one or more cratons including North Australia, South Australia, and (or) East Antarctica. At ca. 1.45 Ga, both the Belt-Purcell and southwest successions underwent major sedimentological changes, with a pronounced shift to Laurentian provenance and the disappearance of the 1.61–1.50 Ga detrital zircon. Upper Belt-Purcell strata contain strongly unimodal ca. 1.73 Ga detrital zircon age populations that match the detrital zircon signature of Paleoproterozoic metasedimentary rocks of the Yavapai province to the south and southeast. We propose that the shift at ca. 1.45 Ga records the onset of orogenesis in southern Laurentia coeval with rifting along its northwestern margin. Bedrock uplift associated with orogenesis and widespread, coeval magmatism caused extensive exhumation and erosion of the Yavapai province ca. 1.45–1.36 Ga, providing a voluminous and areally extensive sediment source–with suitable zircon ages–during upper Belt deposition. This model provides a comprehensive and integrated view of the Mesoproterozoic tectonic evolution of western Laurentia and its position within the supercontinent Columbia as it evolved into Rodinia.

Extensional vs. compressional deformation in the Central High Atlas salt province: A paleomagnetic approach

NASA Astrophysics Data System (ADS)

Calvín, P.; Casas-Sainz, A. M.; Villalaín, J. J.; Moussaid, B.

2018-06-01

In this paper we address the problem of the distinction between diapiric, salt-driven and compressional structures, using the outstanding example of the Central High Atlas (Morocco). A remagnetized component carried by magnetite has been isolated in 32 new paleomagnetic sites. It is characterized by: maximum unblocking temperatures around 450 °C, syn-folding behavior and normal polarity. These 33 mean paleomagnetic directions were analyzed together with other 68 from published works around the study area to construct a robust paleomagnetic dataset along a cross-section perpendicular to the main structures. The remagnetization direction (n: 100, Dec: 332.2°, Inc: 34.5°, η: 6.2°, ξ: 2.0°, A/n: 6.427°) and the paleo-dip of beds (the attitude of the beds at the remagnetization occurrence) were calculated through small circle methods. The remagnetization can be dated as ca. 100 Ma. Because of its occurrence between the extensional and compressional periods, this remagnetization offers the possibility of restore the basin to its pre-inversion geometry. Comparison between present-day and pre-inversion structure allows discriminating three different evolutionary patterns: (i) thrusted and welded salt-walls mainly structured during the extensional stage (Ikkou ridge) with steep limbs close to the salt-wall core. (ii) Jurassic salt-walls with weaker deformation, restricted to the areas adjacent to the structure (Tadaghmamt and Timedouine); in this case, Cenozoic compression is limited to welding of the salt-walls and buttressing of the sedimentary sequences against faults. (iii) salt-rollers gently initiated during the Jurassic (Toumliline diapir), thrusted during the Cenozoic compression. Results show the importance of salt tectonics both during extension and compression, as well as the control of the compressional features by the inherited extensional structures. The performed restorations prove that paleomagnetism is a useful, independent tool to obtain palinspastic restorations and to separate, and quantify, the imprint generated during the basinal stage from the inversional features.

Advanced Multivariate Inversion Techniques for High Resolution 3D Geophysical Modeling

DTIC Science & Technology

2011-09-01

of seismic ambient noise – has been used to image crustal Vs variation with a lateral resolution upward of 100 km either on regional or on sub...to East Africa, we solve for velocity structure in an area with less lateral heterogeneity but great tectonic complexity. To increase the...demonstrate correlation with crustal geology. Figure 1 shows the 3D S-wave velocity model obtained from the joint inversion. The low-velocity anomaly

3D Modeling of Iran and Surrounding Areas from Simultaneous Inversion of Multiple Geophysical Datasets (Postprint). Annual Report 3

DTIC Science & Technology

2012-03-22

2003). This is particularly true at shallow depths where the shorter periods, which are primarily sensitive to upper crustal structures, are difficult...to measure, and especially true in tectonically and geologically complex areas. On the other hand, regional gravity inversions have the greatest...the slower deep crustal speeds into the Caspian region does not make sense geologically. These effects are driven by the simple Laplacian smoothness

Coxsackievirus protein 2B modifies endoplasmic reticulum membrane and plasma membrane permeability and facilitates virus release.

PubMed Central

van Kuppeveld, F J; Hoenderop, J G; Smeets, R L; Willems, P H; Dijkman, H B; Galama, J M; Melchers, W J

1997-01-01

Digital-imaging microscopy was performed to study the effect of Coxsackie B3 virus infection on the cytosolic free Ca2+ concentration and the Ca2+ content of the endoplasmic reticulum (ER). During the course of infection a gradual increase in the cytosolic free Ca2+ concentration was observed, due to the influx of extracellular Ca2+. The Ca2+ content of the ER decreased in time with kinetics inversely proportional to those of viral protein synthesis. Individual expression of protein 2B was sufficient to induce the influx of extracellular Ca2+ and to release Ca2+ from ER stores. Analysis of mutant 2B proteins showed that both a cationic amphipathic alpha-helix and a second hydrophobic domain in 2B were required for these activities. Consistent with a presumed ability of protein 2B to increase membrane permeability, viruses carrying a mutant 2B protein exhibited a defect in virus release. We propose that 2B gradually enhances membrane permeability, thereby disrupting the intracellular Ca2+ homeostasis and ultimately causing the membrane lesions that allow release of virus progeny. PMID:9218794

Full-waveform inversion for the Iranian plateau

NASA Astrophysics Data System (ADS)

Masouminia, N.; Fichtner, A.; Rahimi, H.

2017-12-01

We aim to obtain a detailed tomographic model for the Iranian plateau facilitated by full-waveform inversion. By using this method, we intend to better constrain the 3-D structure of the crust and the upper mantle in the region. The Iranian plateau is a complex tectonic area resulting from the collision of the Arabian and Eurasian tectonic plates. This region is subject to complex tectonic processes such as Makran subduction zone, which runs along the southeastern coast of Iran, and the convergence of the Arabian and- Eurasian plates, which itself led to another subduction under Central Iran. This continent-continent collision has also caused shortening and crustal thickening, which can be seen today as Zagros mountain range in the south and Kopeh Dagh mountain range in the northeast. As a result of such a tectonic activity, the crust and the mantle beneath the region are expected to be highly heterogeneous. To further our understanding of the region and its tectonic history, a detailed 3-D velocity model is required.To construct a 3-D model, we propose to use full-waveform inversion, which allows us to incorporate all types of waves recorded in the seismogram, including body waves as well as fundamental- and higher-mode surface waves. Exploiting more information from the observed data using this approach is likely to constrain features which have not been found by classical tomography studies so far. We address the forward problem using Salvus - a numerical wave propagation solver, based on spectral-element method and run on high-performance computers. The solver allows us to simulate wave field propagating in highly heterogeneous, attenuating and anisotropic media, respecting the surface topography. To improve the model, we solve the optimization problem. Solution of this optimization problem is based on an iterative approach which employs adjoint methods to calculate the gradient and uses steepest descent and conjugate-gradient methods to minimize the objective function. Each iteration of such an approach is expected to bring the model closer to the true model.Our model domain extends between 25°N and 40°N in latitude and 42°E and 63°E in longitude. To constrain the 3-D structure of the area we use 83 broadband seismic stations and 146 earthquakes with magnitude Mw>4.5 -that occurred in the region between 2012 and 2017.

Near real time inverse source modeling and stress filed assessment: the requirement of a volcano fast response system

NASA Astrophysics Data System (ADS)

Shirzaei, Manoochehr; Walter, Thomas

2010-05-01

Volcanic unrest and eruptions are one of the major natural hazards next to earthquakes, floods, and storms. It has been shown that many of volcanic and tectonic unrests are triggered by changes in the stress field induced by nearby seismic and magmatic activities. In this study, as part of a mobile volcano fast response system so-called "Exupery" (www.exupery-vfrs.de) we present an arrangement for semi real time assessing the stress field excited by volcanic activity. This system includes; (1) an approach called "WabInSAR" dedicated for advanced processing of the satellite data and providing an accurate time series of the surface deformation [1, 2], (2) a time dependent inverse source modeling method to investigate the source of volcanic unrest using observed surface deformation data [3, 4], (3) the assessment of the changes in stress field induced by magmatic activity at the nearby volcanic and tectonic systems. This system is implemented in a recursive manner that allows handling large 3D data sets in an efficient and robust way which is requirement of an early warning system. We have applied and validated this arrangement on Mauna Loa volcano, Hawaii Island, to assess the influence of the time dependent activities of Mauna Loa on earthquake occurrence at the Kaoiki seismic zone. References [1] M. Shirzaei and T. R. Walter, "Wavelet based InSAR (WabInSAR): a new advanced time series approach for accurate spatiotemporal surface deformation monitoring," IEEE, pp. submitted, 2010. [2] M. Shirzaei and R. T. Walter, "Deformation interplay at Hawaii Island through InSAR time series and modeling," J. Geophys Res., vol. submited, 2009. [3] M. Shirzaei and T. R. Walter, "Randomly Iterated Search and Statistical Competency (RISC) as powerful inversion tools for deformation source modeling: application to volcano InSAR data," J. Geophys. Res., vol. 114, B10401, doi:10.1029/2008JB006071, 2009. [4] M. Shirzaei and T. R. Walter, "Genetic algorithm combined with Kalman filter as powerful tool for nonlinear time dependent inverse modelling: Application to volcanic deformation time series," J. Geophys. Res., pp. submitted, 2010.

Stratigraphy, geochronology and regional tectonic setting of the Late Cretaceous (ca. 82-70 Ma) Cabullona basin, Sonora, Mexico

NASA Astrophysics Data System (ADS)

González-León, Carlos M.; Solari, Luigi A.; Madhavaraju, Jayagopal

2017-12-01

The Cabullona basin in northeastern Sonora is a continental depocenter whose origin is related to the adjacent Sierra Anibacachi uplift that bounds its tectonic eastern flank. Its exposed, mostly fluvial and lacustrine sedimentary fill, the Cabullona Group, was deposited between 81.9 ± 0.7 and 69.8 ± 0.7 Ma and its outcrops extends for 70 km from north to south. The oldest measured stratigraphic column of the Cabullona Group is the Los Atolillos column of the southern part of the basin, but its base is not exposed. A basal conglomerate in the younger El Malacate (ca. 80 Ma), Cuauhtémoc (ca. 75 Ma) and San Joaquín (ca. 70 Ma) columns onlaps deformed basement rocks. The type section in which the Cabullona Group was previously named is herein referred as the Naco section and is dated ∼73-72 Ma. The younger strata of the Cabullona Group correspond to the fluvial San Joaquín column that onlaps the eastern tectonic boundary of the basin and to the lacustrine Esqueda column. These columns are dated at ca. 70 Ma and may represent the late evolution of the Cabullona basin. Sandstone petrography and detrital zircon geochronology are used to infer provenance of sediments of the Cabullona Group. Sandstones consist of lithic arkose to feldespathic litharenite, indicating provenance from dissected to transitional volcanic arc, but samples of the El Malacate column classify as arkose and lithic arkose with possible provenance from basement uplift of Sierra Los Ajos; litharenite from the Esqueda column indicate arc provenance. Detrital zircons yielded mostly Proterozoic and Mesozoic ages with age peaks at ca. 1568, 167, 100, 80 and 73 Ma indicating possible provenance from the Precambrian basement rocks and the Jurassic continental magmatic arc that underlie the region, the Alisitos arc and La Posta plutons in Baja California, and from the Laramide magmatic arc of Sonora. The Cabullona basin developed nearly contemporaneous to the early, eastwards migrating Laramide magmatic arc that located to the west of the basin, and to a tectonic shortening that occurred in northern Sonora during Late Cretaceous time. In the older columns of the Cabullona Group and in columns of the northern part, the early arc had a distal influence during sedimentation as shown by interbedded ash fall tuffs and minor rhyolitic flows, but sections in the southern part of the basin record more abundant rhyolitic ash-fall tuffs and flows indicating the arc proximity. An important regional flare-up of the arc at ca. 74 Ma is recorded by the Ejido Ruiz Cortines column, while the upper part of the Cabullona Group was interdigitating with rhyolitic rocks by 70 Ma. The Cabullona basin started to form during the shortening event whose age is constrained between ca. 93 and 76 Ma according to U-Pb ages of the syntectonic Cocóspera Formation of northern Sonora and from Laramide arc rocks that overlie it. Ages and correlation of the Cocóspera and the Altar formations may indicate that a Laramide tectonic front extended from north-central Sonora to the Caborca region and whose trace may correspond to a westward extension of the San Antonio fault.

Paleoseismic study of the Kamishiro Fault on the northern segment of the Itoigawa-Shizuoka Tectonic Line, Japan

NASA Astrophysics Data System (ADS)

Lin, Aiming; Sano, Mikako; Wang, Maomao; Yan, Bing; Bian, Di; Fueta, Ryoji; Hosoya, Takashi

2017-07-01

The Mw 6.2 (Mj 6.8) Nagano (Japan) earthquake of 22 November 2014 produced a 9.3-km long surface rupture zone with a thrust-dominated displacement of up to 1.5 m, which duplicated the pre-existing Kamishiro Fault along the Itoigawa-Shizuoka Tectonic Line (ISTL), the plate-boundary between the Eurasian and North American plates, northern Nagano Prefecture, central Japan. To characterize the activity of the seismogenic fault zone, we conducted a paleoseismic study of the Kamishiro Fault. Field investigations and trench excavations revealed that seven morphogenic paleohistorical earthquakes (E2-E8) prior to the 2014 Mw 6.2 Nagano earthquake (E1) have occurred on the Kamishiro Fault during the last ca. 6000 years. Three of these events (E2-E4) are well constrained and correspond to historical earthquakes occurring in the last ca. 1200 years. This suggests an average recurrence interval of ca. 300-400 years on the seismogenic fault of the 2014 Kamishiro earthquake in the past 1200 years. The most recent event prior to the 2014 earthquakes (E1) is E2 and the penultimate and antepenultimate faulting events are E3 and E4, respectively. The penultimate faulting event (E3) occurred during the period of AD 1800-1400 and is associated with the 1791 Mw 6.8 earthquake. The antepenultimate faulting event (E4) is inferred to have occurred during the period of ca. AD 1000-700, likely corresponding to the AD 841 Mw 6.5 earthquake. The oldest faulting event (E8) in the study area is thought to have occurred during the period of ca. 5600-6000 years. The throw rate during the early Holocene is estimated to be 1.2-3.3 mm/a (average, 2.2 mm/a) with an average amount of characteristic offset of 0.7-1.1 m produced by individual event. When compared with active intraplate faults on Honshu Island, Japan, these slip rates and recurrence interval estimated for morphogenic earthquakes on the Kamishiro Fault along the ISTL appear high and short, respectively. This indicates that present activity on this fault is closely related to seismic faulting along the plate boundary between the Eurasian and North American plates.

Paleoseismic study of the Kamishiro Fault on the northern segment of the Itoigawa-Shizuoka Tectonic Line, Japan.

PubMed

Lin, Aiming; Sano, Mikako; Wang, Maomao; Yan, Bing; Bian, Di; Fueta, Ryoji; Hosoya, Takashi

2017-01-01

The M w 6.2 (Mj 6.8) Nagano (Japan) earthquake of 22 November 2014 produced a 9.3-km long surface rupture zone with a thrust-dominated displacement of up to 1.5 m, which duplicated the pre-existing Kamishiro Fault along the Itoigawa-Shizuoka Tectonic Line (ISTL), the plate-boundary between the Eurasian and North American plates, northern Nagano Prefecture, central Japan. To characterize the activity of the seismogenic fault zone, we conducted a paleoseismic study of the Kamishiro Fault. Field investigations and trench excavations revealed that seven morphogenic paleohistorical earthquakes (E2-E8) prior to the 2014 M w 6.2 Nagano earthquake (E1) have occurred on the Kamishiro Fault during the last ca. 6000 years. Three of these events (E2-E4) are well constrained and correspond to historical earthquakes occurring in the last ca. 1200 years. This suggests an average recurrence interval of ca. 300-400 years on the seismogenic fault of the 2014 Kamishiro earthquake in the past 1200 years. The most recent event prior to the 2014 earthquakes (E1) is E2 and the penultimate and antepenultimate faulting events are E3 and E4, respectively. The penultimate faulting event (E3) occurred during the period of AD 1800-1400 and is associated with the 1791 M w 6.8 earthquake. The antepenultimate faulting event (E4) is inferred to have occurred during the period of ca. AD 1000-700, likely corresponding to the AD 841 M w 6.5 earthquake. The oldest faulting event (E8) in the study area is thought to have occurred during the period of ca. 5600-6000 years. The throw rate during the early Holocene is estimated to be 1.2-3.3 mm/a (average, 2.2 mm/a) with an average amount of characteristic offset of 0.7-1.1 m produced by individual event. When compared with active intraplate faults on Honshu Island, Japan, these slip rates and recurrence interval estimated for morphogenic earthquakes on the Kamishiro Fault along the ISTL appear high and short, respectively. This indicates that present activity on this fault is closely related to seismic faulting along the plate boundary between the Eurasian and North American plates.

Deep conductivity characteristics and preliminary acquaintance of the Lushan earthquake, east edge of Tibetan Plateau, China

NASA Astrophysics Data System (ADS)

Zhou, J.; Wang, X.; Wang, Y.; Min, G.

2013-12-01

1. Introduction The Longmenshan foreland basin developed as a flexural foredeep at western Yangtze Platfrom during the Late Triassic Indosinian orogeny with strong tectonic activity. 2008 Wenchuan earthquake (Mw7.9) happened along the middle segment of the Longmenshan overthrusting belt. 2013 Lushan earthquake (Mw6.6) occurred along the south segment of Longmenshan tectonic zone which belongs to seismic gap during the Wenchuan earthquake. The recent researches ( Yan Zhan etc., 2013; Zhuqi Zhang etc., 2013; Xiwei Xu etc., 2013) indicate that the Lushan earthquake may closely related to the activity of Longmenshan ';s piedmont fault zone while the seismogenic fault and other issues are still controversial. In order to provide an electromagnetic basis in deep earthquake area structure, we detect magnetotelluric(MT) sounding in Lushan earthquake zone to obtain the electrical structure characteristics of Longmenshan's south segment. 2. Data acquisition and processing To research the deep electrical structure of earthquake zone assigning a MT profile through the epicenter which transects the Sichuan platform concave, Longmenshan tectonic belt and Songpan-Ganzi fold system. To analysis the MT data, we carried out the impedance tensor decompositionincluding the swift rotation and bahr method which based on the phase deviation. Ultimately, NLCG method was adopted to inverse MT data. 3. Conclusion The result of MT data discloses deep electrical structure feature of the southern section of Longmenshan overthrusting belt: the burial depth of conductive layer in the upper crust of Songpan-Ganzi plot is larger than that of middle-northern part; there is no conductive zone in Longmenshan high resistance body which connect with the high conductivity layer in the crust of the western section of Songpan-Ganzi plot; there exists a relatively large range of conductive zone in the basin to Longmenshan tectonic belt, which is mostly related to the piedmont of concealed fault zone and resistive intermediate belt at the edge of western basin. Be different form Wenchuan earthquake, Lushan earthquake located in the south of Longmenshan tectonic zone which have a strong connection with the piedmont fault. MT research reveals the difference of the deep electrical structure between the south of Longmenshan tectonic belt and the middle-north belt, from which we can infer that the seismogenic environment are not the same. The epicenter of Lushan earthquake occurred in the east edge of Longmenshan tectonic belt which close to Longmenshan ';s piedmont fault combine with the MT inversion infer that Lushan earthquake has a stronger relationship with Longmenshan ';s piedmont fault. Because of the short term of our work, now further work is ongoing.

Tectonic reversal of the western Doruneh Fault System: Implications for Central Asian tectonics

NASA Astrophysics Data System (ADS)

Javadi, Hamid Reza; Esterabi Ashtiani, Marzieh; Guest, Bernard; Yassaghi, Ali; Ghassemi, Mohammad Reza; Shahpasandzadeh, Majid; Naeimi, Amir

2015-10-01

The left-lateral Doruneh Fault System (DFS) bounds the north margin of the Central Iranian microplate and has played an important role in the structural evolution of the Turkish-Iranian plateau. The western termination of the DFS is a sinistral synthetic branch fault array that shows clear kinematic evidence of having undergone recent slip sense inversion from a dextral array to a sinistral array in the latest Neogene or earliest Quaternary. Similarly, kinematic evidence from the Anarak Metamorphic complex suggests that this complex initially developed at a transpressive left-stepping termination of the DFS and that it was inverted in the latest Neogene to a transtensional fault termination. The recognition that the DFS and other faults in NE Iran were inverted from dextral to sinistral strike slip in the latest Neogene and the likely connection between the DFS and the Herat Fault of Afghanistan suggests that prior to the latest Miocene, all of the north Iranian and northern Afghan ranges were part of a distributed dextral fault network that extended from the west Himalayan syntaxes to the western Alborz. Also, the recognition that regional slip sense inversion occurred across northern and northeastern Iran after the latest Miocene invalidates tectonic models that extrapolate Pleistocene to recent fault slip kinematics and rates back beyond this time.

Extension joints: a tool to infer the active stress field orientation (case study from southern Italy)

NASA Astrophysics Data System (ADS)

De Guidi, Giorgio; Caputo, Riccardo; Scudero, Salvatore; Perdicaro, Vincenzo

2013-04-01

An intense tectonic activity in eastern Sicily and southern Calabria is well documented by the differential uplift of Late Quaternary coastlines and by the record of the strong historical earthquakes. The extensional belt that crosses this area is dominated by a well established WNW-ESE-oriented extensional direction. However, this area is largely lacking of any structural analysis able to define the tectonics at a more local scale. In the attempt to fill this gap of knowledge, we carried out a systematic analysis of extension joint sets. In fact, the systematic field collection of these extensional features, coupled with an appropriate inversion technique, allows to determine the characteristic of the causative tectonic stress field. Joints are defined as outcrop-scale mechanical discontinuities showing no evidence of shear motion and being originated as purely extensional fractures. Such tectonic features are one of the most common deformational structures in every tectonic environment and particularly abundant in the study area. A particular arrangement of joints, called "fracture grid-lock system", and defined as an orthogonal joint system where mutual abutting and crosscutting relationships characterize two geologically coeval joint sets, allow to infer the direction and the magnitude of the tectonic stress field. We performed the analyses of joints only on Pleistocene deposits of Eastern Sicily and Southern Calabria. Moreover we investigated only calcarenite sediments and cemented deposits, avoiding claysh and loose matrix-supported clastic sediments where the deformation is generally accomodated in a distributed way through the relative motion between the single particles. In the selection of the sites, we also took into account the possibility to clearly observe the geometric relationships among the joints. For this reason we chose curvilinear road cuts or cliffs, wide coastal erosional surfaces and quarries. The numerical inversions show a similar stress tensors at all the investigated sites. Indeed, the maximum principal stress axis σ1 is vertical or subvertical, while the intermediate and the least axes (σ2 and σ3) lie on the horizontal plane or show low plunging values. The main direction of extension (σ3) at each site is in general agreement with the first-order regional stress field (WNW-ESE) even though some local perturbations have been recognized. These are interpreted as due to interferences between large active faults and their particular geometrical arrangement. In particular local stress deflections and stress swaps systematically occur in zones characterized by two overlapping fault segments or close to their tips.

Arctic and N Atlantic Crustal Thickness and Oceanic Lithosphere Distribution from Gravity Inversion

NASA Astrophysics Data System (ADS)

Kusznir, Nick; Alvey, Andy

2014-05-01

The ocean basins of the Arctic and N. Atlantic formed during the Mesozoic and Cenozoic as a series of distinct ocean basins, both small and large, leading to a complex distribution of oceanic crust, thinned continental crust and rifted continental margins. The plate tectonic framework of this region was demonstrated by the pioneering work of Peter Ziegler in AAPG Memoir 43 " Evolution of the Arctic-North Atlantic and the Western Tethys" published in 1988. The spatial evolution of Arctic Ocean and N Atlantic ocean basin geometry and bathymetry are critical not only for hydrocarbon exploration but also for understanding regional palaeo-oceanography and ocean gateway connectivity, and its influence on global climate. Mapping crustal thickness and oceanic lithosphere distribution represents a substantial challenge for the Polar Regions. Using gravity anomaly inversion we have produced comprehensive maps of crustal thickness and oceanic lithosphere distribution for the Arctic and N Atlantic region, We determine Moho depth, crustal basement thickness, continental lithosphere thinning and ocean-continent transition location using a 3D spectral domain gravity inversion method, which incorporates a lithosphere thermal gravity anomaly correction (Chappell & Kusznir 2008). Gravity anomaly and bathymetry data used in the gravity inversion are from the NGA (U) Arctic Gravity Project and IBCAO respectively; sediment thickness is from a new regional compilation. The resulting maps of crustal thickness and continental lithosphere thinning factor are used to determine continent-ocean boundary location and the distribution of oceanic lithosphere. Crustal cross-sections using Moho depth from the gravity inversion allow continent-ocean transition structure to be determined and magmatic type (magma poor, "normal" or magma rich). Our gravity inversion predicts thin crust and high continental lithosphere thinning factors in the Eurasia, Canada, Makarov, Podvodnikov and Baffin Basins consistent with these basins being oceanic. Larger crustal thicknesses, in the range 20 - 30 km, are predicted for the Lomonosov, Alpha and Mendeleev Ridges. Crustal basement thicknesses of 10-15 km are predicted under the Laptev Sea which is interpreted as highly thinned continental crust formed at the eastward continuation of Eurasia Basin sea-floor spreading. Thin continental or oceanic crust of thickness 7 km or less is predicted under the North Chukchi Basin and has major implications for understanding the Mesozoic and Cenozoic plate tectonic history of the Siberian and Chukchi Amerasia Basin margins. Restoration of crustal thickness and continent-ocean boundary location from gravity inversion may be used to test and refine plate tectonic reconstructions. Using crustal thickness and continental lithosphere thinning factor maps with superimposed shaded-relief free-air gravity anomaly, we improve the determination of pre-breakup rifted margin conjugacy and sea-floor spreading trajectory within the Arctic and N Atlantic basins. By restoring crustal thickness & continental lithosphere thinning maps of the Eurasia Basin & NE Atlantic to their initial post-breakup configuration we show the geometry and segmentation of the rifted continental margins at their time of breakup, together with the location of highly-stretched failed breakup basins and rifted micro-continents. We interpret gravity inversion crustal thicknesses underneath Morris Jessop Rise & Yermak Plateau as continental crust which provided a barrier to the tectonic and palaeo-oceanic linkage between the Arctic & North Atlantic until the Oligocene. Before this time, we link the seafloor spreading within the Eurasia Basin to that in Baffin Bay.

Oil core microcapsules by inverse gelation technique.

PubMed

Martins, Evandro; Renard, Denis; Davy, Joëlle; Marquis, Mélanie; Poncelet, Denis

2015-01-01

A promising technique for oil encapsulation in Ca-alginate capsules by inverse gelation was proposed by Abang et al. This method consists of emulsifying calcium chloride solution in oil and then adding it dropwise in an alginate solution to produce Ca-alginate capsules. Spherical capsules with diameters around 3 mm were produced by this technique, however the production of smaller capsules was not demonstrated. The objective of this study is to propose a new method of oil encapsulation in a Ca-alginate membrane by inverse gelation. The optimisation of the method leads to microcapsules with diameters around 500 μm. In a search of microcapsules with improved diffusion characteristics, the size reduction is an essential factor to broaden the applications in food, cosmetics and pharmaceuticals areas. This work contributes to a better understanding of the inverse gelation technique and allows the production of microcapsules with a well-defined shell-core structure.

Mesozoic evolution of the northeast African shelf margin, Libya and Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aadland, R.K.; Schamel, S.

1988-08-01

The present tectonic features of the northeast African shelf margin between the Nile delta and the Gulf of Sirte are products of (1) precursory late Paleozoic basement arches, (2) early Mesozoic rifting and plate separation, and (3) Late Cretaceous structural inversion. Isopach and structural maps, cross sections, and sediment accumulation (geohistory) curves constructed from 89 wells in the Western Desert and 27 wells in northeastern Libya depict the structural and stratigraphic development of the northeast African shelf margin.

Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aftalion, M.; Bowes, D.R.; Dash, B.

1988-11-01

Charnockite formation in the Angul district of Orissa took place between 1088 + 26/ -17 Ma, the U-Pb zircon upper intercept crystallization age of a leptynite neosome, and 957 +8/ -4-956 {plus minus} 4 Ma, the U-Pb zircon-monazite upper intercept and U-Pb monazite crystallization ages of a granite. Confirmation of the Proterozoic age of the charnockites is given by (1) a U-Pb zircon upper intercept 1159 + 59/ -30 Ma age and a Rb-Sr whole-rock 1080 {plus minus} 65 Ma age for an augen gneiss which pre-dates the leptynite, and (2) U-Pb monazite ages of 973 {plus minus} 5,964 {plusmore » minus} 4, and 953 {plus minus} 4 Ma for a gray quartzofeldspathic gneiss, the augen gneiss, and the leptynite, respectively: these late Proterozoic dates are interpreted as representing ages recorded during charnockitization. The ca. 950-980 Ma charnockite- and granite-forming events are related to the evolution of mantle-derived, CO{sub 2}-bearing basic magma emplaced into the deeper levels of an extensional tectonic-transcurrent fault regime. The ca. 1100-1150 Ma tectonothermal and igneous events represent compressional tectonism in reactivated crystalline basement in the late mid-Proterozoic Eastern Ghats orogenic belt.« less

Late Cretaceous (ca. 95 Ma) magnesian andesites in the Biluoco area, southern Qiangtang subterrane, central Tibet: Petrogenetic and tectonic implications

NASA Astrophysics Data System (ADS)

He, Haiyang; Li, Yalin; Wang, Chengshan; Zhou, Aorigele; Qian, Xinyu; Zhang, Jiawei; Du, Lintao; Bi, Wenjun

2018-03-01

The tectonic evolutionary history of the Lhasa and Qiangtang collision zones remains hotly debated because of the lack of pivotal magmatic records in the southern Qiangtang subterrane, central Tibet. We present zircon U-Pb dating, whole-rock major and trace-element geochemical analyses, and Sr-Nd isotopic data for the newly discovered Biluoco volcanic rocks from the southern Qiangtang subterrane, central Tibet. Zircon U-Pb dating reveals that the Biluoco volcanic rocks were crystallized at ca. 95 Ma. The samples are characterized by low SiO2 (50.26-54.53 wt%), high Cr (109.7-125.92 ppm) and Ni (57.4-71.58 ppm), and a high Mg# value (39-56), which plot in the magnesian andesites field on the rock classification diagram. They display highly fractionated rare earth element patterns with light rare earth element enrichment ([La/Yb]N = 21.04-25.24), high Sr/Y (63.97-78.79) and no negative Eu anomalies (Eu/Eu* = 0.98-1.04). The Biluoco volcanic rocks are depleted in Nb, Ta and Ti and enriched in Ba, Th, U and Pb. Moreover, the eight samples of Biluoco volcanic rocks display constant (87Sr/86Sr)i ratios (0.70514-0.70527), a positive εNd(t) value (2.16-2.68) and younger Nd model ages (0.56-0.62 Ga). These geochemical signatures indicate that the Biluoco volcanic rocks were most likely derived from partial melting of the mantle wedge peridotite metasomatized by melts of subducted slab and sediment in the subducted slab, invoked by asthenospheric upwelling resulting from the slab break-off of the northward subduction of the Bangong-Nujiang oceanic lithosphere. Identification of ca. 95 Ma Biluoco magnesian andesites suggests they were a delayed response of slab break-off of the northward subduction of the Bangong-Nujiang oceanic lithosphere at ca. 100 Ma.

Ciproxifan, a histamine H{sub 3} receptor antagonist and inverse agonist, presynaptically inhibits glutamate release in rat hippocampus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Cheng-Wei; Lin, Tzu-Yu

2017-03-15

Ciproxifan is an H{sub 3} receptor antagonist and inverse agonist with antipsychotic effects in several preclinical models; its effect on glutamate release has been investigated in the rat hippocampus. In a synaptosomal preparation, ciproxifan reduced 4-aminopyridine (4-AP)-evoked Ca{sup 2+}-dependent glutamate release and cytosolic Ca{sup 2+} concentration elevation but did not affect the membrane potential. The inhibitory effect of ciproxifan on 4-AP-evoked glutamate release was prevented by the Gi/Go-protein inhibitor pertussis toxin and Ca{sub v}2.2 (N-type) and Ca{sub v}2.1 (P/Q-type) channel blocker ω-conotoxin MVIIC, but was not affected by the intracellular Ca{sup 2+}-release inhibitors dantrolene and CGP37157. Furthermore, the phospholipase A{submore » 2} (PLA{sub 2}) inhibitor OBAA, prostaglandin E{sub 2} (PGE{sub 2}), PGE2 subtype 2 (EP{sub 2}) receptor antagonist PF04418948, and extracellular signal-regulated kinase (ERK) inhibitor FR180204 eliminated the inhibitory effect of ciproxifan on glutamate release. Ciproxifan reduced the 4-AP-evoked phosphorylation of ERK and synapsin I, a presynaptic target of ERK. The ciproxifan-mediated inhibition of glutamate release was prevented in synaptosomes from synapsin I-deficient mice. Moreover, ciproxifan reduced the frequency of miniature excitatory postsynaptic currents without affecting their amplitude in hippocampal slices. Our data suggest that ciproxifan, acting through the blockade of Gi/Go protein-coupled H{sub 3} receptors present on hippocampal nerve terminals, reduces voltage-dependent Ca{sup 2+} entry by diminishing PLA{sub 2}/PGE{sub 2}/EP{sub 2} receptor pathway, which subsequently suppresses the ERK/synapsin I cascade to decrease the evoked glutamate release. - Highlights: • Ciproxifan presynaptically reduces glutamate release in the hippocampus in vitro. • Decrease in voltage-dependent Ca{sup 2+} influx is involved. • A role for the PLA{sub 2}/PGE{sub 2}/EP{sub 2} pathway in the action of ciproxifan is suggested. • Decreased ERK and synapsin I activity is also involved. • This study provides new insight into the mode by which ciproxifan acts in the brain.« less

Some fundamental questions about the evolution of the Sea of Japan back-arc

NASA Astrophysics Data System (ADS)

Van Horne, A.; Sato, H.; Ishiyama, T.

2016-12-01

The Japanese island arc separated from Asia through the rifting of an active continental margin, and the opening of the Sea of Japan back-arc, in the middle Miocene. Due to its complex tectonic setting, the Sea of Japan back-arc was affected by multiple external events contemporary with its opening, including a plate reorganization, the opening of at least two other nearby back-arcs (Shikoku Basin and Okhotsk Sea/Kuril Basin), and two separate arc-arc collisions, involving encroachment upon Japan of the Izu-Bonin and Kuril arcs. Recent tectonic inversion has exposed entire sequences of back-arc structure on land, which remain virtually intact because of the short duration of inversion. Japan experiences a high level of seismic activity due to its position on the overriding plate of an active subduction margin. Continuous geophysical monitoring via a dense nationwide seismic/geodetic network, and a program of controlled-source refraction/wide-angle reflection profiling, directed towards earthquake hazard mitigation, have made it the repository of a rich geophysical data set through which to understand the processes that have shaped back-arc development. Timing, structural evolution, and patterns of magmatic activity during back-arc opening in the Sea of Japan were established by earlier investigations, but fundamental questions regarding back-arc development remain outstanding. These include (1) timing of the arrival of the Philippine Sea plate in southwest Japan, (2) the nature of the plate boundary prior to its arrival, (3) the pre-rift location of the Japanese island arc when it was attached to Asia, (4) the mechanism of back-arc opening (pull-apart or trench retreat), (5) the speed of opening, (6) simultaneous or sequential development of the multi-rift system, (7) the origin of the anomalously thick Yamato Basin ocean crust, and (8) the pattern of concentrated deformation in the failed-rift system of the eastern Sea of Japan since tectonic inversion. Resolving uncertainties like those posed here will be necessary for a more complete understanding of the nature of and processes involved in back-arc development in the Sea of Japan.

The Proterozoic of NW Mexico revisited: U-Pb geochronology and Hf isotopes of Sonoran rocks and their tectonic implications

NASA Astrophysics Data System (ADS)

Solari, L. A.; González-León, C. M.; Ortega-Obregón, C.; Valencia-Moreno, M.; Rascón-Heimpel, M. A.

2018-04-01

Several Proterozoic basement units crop out in the Sonora State of NW Mexico, and the same can be correlated with crustal provinces of southern Laurentia in the neighboring southwestern USA. Zircon U-Pb and Hf isotopic determinations in more than 300 grains separated from igneous and metaigneous rocks from these units indicate that the crystalline basement in Sonora is made up of different components, which are from west to east: (1) The Caborca-Mojave province to the west, characterized by the so-called Bámori Complex, have U-Pb ages between 1696 and 1772 Ma, with moderately juvenile to slightly evolved ɛHf values, yielding T DM ages of ca. 2.1-2.4 Ga; (2) in the intermediate area, east of Hermosillo, the Palofierral and La Ramada orthogneiss units yield an age of 1640 and 1703 Ma, respectively, both having juvenile ɛHf with the Palofierral overlapping the depleted mantle curve at ca. 1.65 Ga; and (3) in the northeastern Sonora, samples from the southern extension of the Mazatzal province, represented by the Pinal Schist, yielded ages between 1674 and 1694 Ma, with moderately juvenile to juvenile ɛHf values and a T DM age of ca. 1.9 Ga. In addition, a suite of post-tectonic granites was also studied in Caborca (San Luis granite) as well as in northeastern Sonora (Cananea granite), both yielding ages of ca. 1.44 Ga with moderately juvenile ɛHf values ranging from -1 to +8 and T DM dates of ca. 1.8-1.9 Ga and 1.6-1.7 Ga, respectively. These two isotopically contrasting provinces may imply the existence of a Proterozoic paleo-suture. However, if the Palofierral gneiss, of which the Hf signature straddles the depleted mantle array, is taken as the source for the 1.44 Ga Cananea granite, then the location of such a suture zone should lay farther south than the proposed trace of the Mojave-Sonora megashear.

Ca(5)Zr(3)F(22).

PubMed

Oudahmane, Abdelghani; El-Ghozzi, Malika; Avignant, Daniel

2012-04-01

Single crystals of Ca(5)Zr(3)F(22), penta-calcium trizirconium docosafluoride, were obtained unexpectedly by solid-state reaction between CaF(2) and ZrF(4) in the presence of AgF. The structure of the title compound is isotypic with that of Sr(5)Zr(3)F(22) and can be described as being composed of layers with composition [Zr(3)F(20)](8-) made up from two different [ZrF(8)](4-) square anti-prisms (one with site symmetry 2) by corner-sharing. The layers extending parallel to the (001) plane are further linked by Ca(2+) cations, forming a three-dimensional network. Amongst the four crystallographically different Ca(2+) ions, three are located on twofold rotation axes. The Ca(2+) ions exhibit coordination numbers ranging from 8 to 12, depending on the cut off, with very distorted fluorine environments. Two of the Ca(2+) ions occupy inter-stices between the layers whereas the other two are located in void spaces of the [Zr(3)F(20)](8-) layer and alternate with the two Zr atoms along [010]. The crystal under investigation was an inversion twin.

Seismotectonics and crustal stress across the northern Arabian plate

NASA Astrophysics Data System (ADS)

yassminh, R.; Gomez, F. G.; Sandvol, E. A.; Ghalib, H. A.; Daoud, M.

2013-12-01

The region encompassing the collision of northern Arabia with Eurasia is a tectonically heterogeneous region of distributed deformation. The northern Arabia plate is bounded to the west by the subducting Sinai plate and the left-lateral Dead Sea transform. This complexity suggests that there are, multiple competing processes that may influence regional tectonics in northern Arabia and adjacent areas. Earthquake mechanisms provide insight into crustal kinematics and stress; however, reliable determination of earthquake source parameters can be challenging in a complex geological region, such as the continental collision zone between the Arabian and Eurasian plates. The goal of this study is to investigate spatial patterns of the crustal stress in the northern Arabian plate and surrounding area. The focal mechanisms used in this study are based on (1) first-motion polarities for earthquakes recorded by Syrian earthquake center during 2000-2011, and (2) regional moment tensors from broadband seismic data, from Turkey and Iraq. First motion focal mechanisms were assigned quality classifications based on the variation of both nodal planes. Regional moment tensor analysis can be significantly influenced by seismic velocity structure; thus, we have divided the study area into regions based on tectonic units. For each region, a specific velocity model is defined using waveform-modeling technique prior to the regional moment tensor inversion. The resulting focal mechanisms, combined with other previously published focal mechanisms for the study area, provide a basis for stress inversion analysis. The resulting deviatoric stress tensors show the spatial distribution of the maximum horizontal stress varies from NW-SE along the Dead Sea Fault to the N-S toward the east. We interpret this to reflect the eastward change from the transform to collision processes in northern Arabia. Along the Dead Sea Fault, transposition of the sigma-1 and sigma-2 to vertical and horizontal, respectively, may relate to influences from the subducted part of the Sinai plate. This change in regional stress is also consistent with extensional strains observed from GPS velocities.

Soil radon profile of the Alhama de Murcia Fault: implications in tectonic segmentation

NASA Astrophysics Data System (ADS)

Bejar-Pizarro, M.; Perez Lopez, R.; Fernández Cortés, A.; Martínez-Díaz, J. J.; Staller, A.; Sánchez-Malo, A.; Sanz, E.; Cuezva, S.; Sánchez-Moral, S.

2017-12-01

Soil radon exhalation in active faults has been reported in several cases. Mobilization of radon gas in tectonic areas is related to CO2emission, acting as gas carrier from deeper fractured zones. Fluctuation of radon values can be correlated with earthquake occurrence. We have used the soil radon emission for characterizing different tectonic segment of the Alhama de Murcia Fault (FAM), one of the most active on-shore tectonic faults in Spain. The FAM is a NE-SW trending strike-slip fault with reverse component, 90 km long and it is capable to trigger M7 earthquakes, as far as several paleoseismic studies shown. The last destructive earthquake took place in 2011 and killed 9 people. Tectonic segmentation of this fault has been proposed, with a tectonic slip-rate close to 0.1 mm/yr from geomorphic evidence, whereas 0.5 mm/yr has been suggested from GPS geodetic measurements. We have developed a perpendicular profile for measuring the soil radon exhalation, in relationship with three principal segments of FAM from west to east: (1) Goñar-Lorca segment, (2) Lorca Totana segment and (3) Alhama segment. We have introduced radon passive detectors equipped with LR115 films in colluvium detritic deposits and at 0.8 m depth. Using detritic deposits affected by Quaternary fault movement we assure equal permeability conditions for radon transport. We used passive closed housings type DRF, with a filter that avoid thoron disturbance. Results show the largest values of radon emission close to the Quaternary surface ruptures (ca 3-5.5 kBq/m3). Furthermore, the Goñar segment exhibits the highest value (6 kBq/m3) although the Lorca segment shows an isotopic signal of 13dCO2 (-7.24‰) which indicates this is a mantle-rootled CO2, i.e. non-soil derived CO2 flux, likely related to CO2 produced by thermal decarbonation of underlying sedimentary rocks containing more marine carbonate minerals. These results are part of the combined Spanish projects GEIs-SUB (CGL2016- 78318-C2-1-R and CGL2016-78318-C2-2-R) and INTERGEO and SISMOSIMA (CGL2013-47412-C2-1-P, CGL2013-47412-C2-2-P).

Integrated geophysical and geological study and petroleum appraisal of Cretaceous plays in the Western Gulf of Gabes, Tunisia

NASA Astrophysics Data System (ADS)

Dkhaili, Noomen; Bey, Saloua; El Abed, Mahmoud; Gasmi, Mohamed; Inoubli, Mohamed Hedi

2015-09-01

An integrated study of available seismic and calibrated wells has been conducted in order to ascertain the structural development and petroleum potential of the Cretaceous Formations of the Western Gulf of Gabes. This study has resulted in an understanding of the controls of deep seated Tethyan tectonic lineaments by analysis of the Cretaceous deposits distribution. Three main unconformities have been identified in this area, unconformity U1 between the Jurassic and Cretaceous series, unconformity U2 separating Early from Late Cretaceous and known as the Austrian unconformity and the major unconformity U3 separating Cretaceous from Tertiary series. The seismic analysis and interpretation have confirmed the existence of several features dominated by an NE-SW extensive tectonic regime evidenced by deep listric faults, asymmetric horst and graben and tilted blocks structures. Indeed, the structural mapping of these unconformities, displays the presence of dominant NW-SE fault system (N140 to N160) bounding a large number of moderate sized basins. A strong inversion event related to the unconformity U3 can be demonstrated by the mapping of the unconformities consequence of the succession of several tectonic manifestations during the Cretaceous and post-Cretaceous periods. These tectonic events have resulted in the development of structural and stratigraphic traps further to the porosity and permeability enhancement of Cretaceous reservoirs.

The thermal history of the Karoo Moatize-Minjova Basin, Tete Province, Mozambique: An integrated vitrinite reflectance and apatite fission track thermochronology study

NASA Astrophysics Data System (ADS)

Fernandes, Paulo; Cogné, Nathan; Chew, David M.; Rodrigues, Bruno; Jorge, Raul C. G. S.; Marques, João; Jamal, Daud; Vasconcelos, Lopo

2015-12-01

The Moatize-Minjova Basin is a Karoo-aged rift basin located in the Tete Province of central Mozambique along the present-day Zambezi River valley. In this basin the Permian Moatize and Matinde formations consist of interbedded carbonaceous mudstones and sandstones with coal seams. The thermal history has been determined using rock samples from two coal exploration boreholes (ca. 500 m depth) to constrain the burial and exhumation history of the basin. Organic maturation levels were determined using vitrinite reflectance and spore fluorescence/colour. Ages and rates of tectonic uplift and denudation have been assessed by apatite fission track analysis. The thermal history was modelled by inverse modelling of the fission track and vitrinite reflectance data. The Moatize Formation attained a coal rank of bituminous coals with low to medium volatiles (1.3-1.7%Rr). Organic maturation levels increase in a linear fashion downhole in the two boreholes, indicating that burial was the main process controlling peak temperature maturation. Calculated palaeogeothermal gradients range from 59 °C/km to 40 °C/km. According to the models, peak burial temperatures were attained shortly (3-10 Ma) after deposition. Apatite fission track ages [146 to 84 Ma (Cretaceous)] are younger than the stratigraphic age. Thermal modelling indicates two episodes of cooling and exhumation: a first period of rapid cooling between 240 and 230 Ma (Middle - Upper Triassic boundary) implying 2500-3000 m of denudation; and a second period, also of rapid cooling, from 6 Ma (late Miocene) onwards implying 1000-1500 m of denudation. The first episode is related to the main compressional deformation event within the Cape Fold Belt in South Africa, which transferred stress northwards on pre-existing transtensional fault systems within the Karoo rift basins, causing tectonic inversion and uplift. During the Mesozoic and most of the Cenozoic the basin is characterized by very slow cooling. The second period of fast cooling and denudation during the Pliocene was likely related to the southward propagation of the East African Rift System into Mozambique.

Polynomial dual energy inverse functions for bone Calcium/Phosphorus ratio determination and experimental evaluation.

PubMed

Sotiropoulou, P; Fountos, G; Martini, N; Koukou, V; Michail, C; Kandarakis, I; Nikiforidis, G

2016-12-01

An X-ray dual energy (XRDE) method was examined, using polynomial nonlinear approximation of inverse functions for the determination of the bone Calcium-to-Phosphorus (Ca/P) mass ratio. Inverse fitting functions with the least-squares estimation were used, to determine calcium and phosphate thicknesses. The method was verified by measuring test bone phantoms with a dedicated dual energy system and compared with previously published dual energy data. The accuracy in the determination of the calcium and phosphate thicknesses improved with the polynomial nonlinear inverse function method, introduced in this work, (ranged from 1.4% to 6.2%), compared to the corresponding linear inverse function method (ranged from 1.4% to 19.5%). Copyright © 2016 Elsevier Ltd. All rights reserved.

Multi-phase inversion tectonics related to the Hendijan-Nowrooz-Khafji Fault activity, Zagros Mountains, SW Iran

NASA Astrophysics Data System (ADS)

Kazem Shiroodi, Sadjad; Ghafoori, Mohammad; Faghih, Ali; Ghanadian, Mostafa; Lashkaripour, Gholamreza; Hafezi Moghadas, Naser

2015-11-01

Distinctive characteristics of inverted structures make them important criteria for the identification of certain structural styles of folded belts. The interpretation of 3D seismic reflection and well data sheds new light on the structural evolution and age of inverted structures associated to the Hendijan-Nowrooz-Khafji Fault within the Persian Gulf Basin and northeastern margin of Afro-Arabian plate. Analysis of thickness variations of growth strata using "T-Z plot" (thickness versus throw plot) method revealed the kinematics of the fault. Obtained results show that the fault has experienced a multi-phase evolutionary history over six different extension and compression deformation events (i.e. positive and negative inversion) between 252.2 and 11.62 Ma. This cyclic activity of the growth fault was resulted from alteration of sedimentary processes during continuous fault slip. The structural development of the study area both during positive and negative inversion geometry styles was ultimately controlled by the relative motion between the Afro-Arabian and Central-Iranian plates.

U-Pb ages and metamorphic evolution of the La Pampa Gneisses: Implications for the evolution of the Chilenia Terrane and Permo-Triassic tectonics of north Central Chile

NASA Astrophysics Data System (ADS)

Álvarez, Javier; Mpodozis, Constantino; Blanco-Quintero, Idael; García-Casco, Antonio; Arriagada, César; Morata, Diego

2013-11-01

The La Pampa Gneisses are an enclave of orthogneisses emplaced within late Paleozoic to Triassic granitoids of the Chollay Batholith, in the Cordillera Frontal, to the east of Vallenar. Previous geochronological data (a Rb/Sr “errorchron” of 415 ± 4 Ma) allowed to some authors to suggest that these rocks were part of the Chilenia Terrane accreted to Gondwana during the Middle Devonian (ca. 390 Ma). New petrographic, chemical and geothermobarometric studies, together with U-Pb geochronological data show that the protolith of the La Pampa Gneisses derives from peraluminous tonalites emplaced during the Pennsylvanian at 306.5 ± 1.8 Ma, ruling out the hypothesis considering these rocks as remnant of the pre-collisional Chilenia basement. The tonalites were metamorphosed between 5.06 and 5.58 kbar and 709-779 °C during the middle Permian (267.6 ± 2.1 Ma), possibly in conjunction with the San Rafael tectonic event and the emplacement of the oldest granitoids of the Chollay Batholith. A new intrusive episode occurred at ca. 240 Ma, followed by exhumation and cooling during a regional Triassic extensional episode.

Evolution Process and Structural Analysis of Precambrian Jirisan Metamorphic and Sancheong Anorthosite Complexes in the Jirisan Province, Yeongnam Massif, Korea

NASA Astrophysics Data System (ADS)

Kang, J. H.; Lee, D. S.

2016-12-01

The Jirisan metamorphic complex consists mainly of schist, blastoporphyritic granite gneiss, granitic gneiss, leucocratic gneiss, biotite gneiss, banded gneiss, migmatitic gneiss and granite gneiss. The Paleoproterozoic (1.87 1.79 Ga) Sancheong anorthosite complex, which intrude it, is classified into massive-type and foliation-type Sancheong anorthosite, Fe-Ti ore body, and mafic granulite which were formed from the multiple fractionation and polybaric crystallization of the coeval and cogenetic magma. These complexes went at least through three times of ductile deformation during Early Proterozoic Late Paleozoic. The D1 deformation formed sheath or "A" type folds and its characteristic orientation was uncertain due to the intensive multi-deformation superimposed after that. The D2 deformation occurred under the EW- or WNW-directed tectonic compression, and formed a regional NS or NNE trend of isoclinal and intrafolial folds and an extensive ductile shear zone accompanied by mylonitization. The D3 deformation occurred under the NS- or NNW-directed tectonic compression environment, and formed an EW or ENE trend of open and tight folds and a partial semibrittle shear zone accompanied by mylonitization, and rearranged the NS-trend pre-D3 structural elements into (E)NE or (W)NW direction. The D2 deformation generally increases from the center toward the margin of Sancheong anorthosite complex but is more intensive in the eastern than western parts of Sancheong anorthosite complex. While the D3 deformation is inversely more intensive in the its western than eastern parts. The D2 and D3 deformations are closely related to the distribution features of Sancheong anorthosite complex. These three tectonic events are expected to give important information in understanding and reconstructing the tectonic movement after the formation of Columbia Supercontinent as well as the present NS-trend tectonic frame of the Jirisan province of the Yeongnam massif, the Korean Peninsula.

An internally consistent inverse model to calculate ridge-axis hydrothermal fluxes

NASA Astrophysics Data System (ADS)

Coogan, L. A.; Dosso, S.

2010-12-01

Fluid and chemical fluxes from high-temperature, on-axis, hydrothermal systems at mid-ocean ridges have been estimated in a number of ways. These generally use simple mass balances based on either vent fluid compositions or the compositions of altered sheeted dikes. Here we combine these approaches in an internally consistent model. Seawater is assumed to enter the crust and react with the sheeted dike complex at high temperatures. Major element fluxes for both the rock and fluid are calculated from balanced stoichiometric reactions. These reactions include end-member components of the minerals plagioclase, pyroxene, amphibole, chlorite and epidote along with pure anhydrite, quartz, pyrite, pyrrhotite, titanite, magnetite, ilmenite and ulvospinel and the fluid species H2O, Mg2+, Ca2+, Fe2+, Na+, Si4+, H2S, H+ and H2. Trace element abundances (Li, B, K, Rb, Cs, Sr, Ba, U, Tl, Mn, Cu, Zn, Co, Ni, Pb and Os) and isotopic ratios (Li, B, O, Sr, Tl, Os) are calculated from simple mass balance of a fluid-rock reaction. A fraction of the Cu, Zn, Pb, Co, Ni, Os and Mn in the fluid after fluid-rock reaction is allowed to precipitate during discharge before the fluid reaches the seafloor. S-isotopes are tied to mineralogical reactions involving S-bearing phases. The free parameters in the model are the amounts of each mineralogical reaction that occurs, the amounts of the metals precipitated during discharge, and the water-to-rock ratio. These model parameters, and their uncertainties, are constrained by: (i) mineral abundances and mineral major element compositions in altered dikes from ODP Hole 504B and the Pito and Hess Deep tectonic windows (EPR crust); (ii) changes in dike bulk-rock trace element and isotopic compositions from these locations relative to fresh MORB glass compositions; and (iii) published vent fluid compositions from basalt-hosted high-temperature ridge axis hydrothermal systems. Using a numerical inversion algorithm, the probability density of different model parameter sets has been computed and thus the probability of different fluid and chemical fluxes. Most data can be fit by the model within their uncertainty. The entire dataset is best-fit with a water-to-rock mass ratio between 1.3 and 2.1 (~1 to 1.5 x10**13 kg yr-1) implying a substantial fraction of the magmatic (latent) heat available to drive the axial hydrothermal system is extracted by these systems. Many element fluxes are better constrained than in previous studies (e.g., Sr: 2 to 7 x10**8 moles yr-1; Ca: 2 to 7 x10**11 moles yr-1). Future developments will use experimental data to further constrain the model.

The genetic algorithm: A robust method for stress inversion

NASA Astrophysics Data System (ADS)

Thakur, Prithvi; Srivastava, Deepak C.; Gupta, Pravin K.

2017-01-01

The stress inversion of geological or geophysical observations is a nonlinear problem. In most existing methods, it is solved by linearization, under certain assumptions. These linear algorithms not only oversimplify the problem but also are vulnerable to entrapment of the solution in a local optimum. We propose the use of a nonlinear heuristic technique, the genetic algorithm, which searches the global optimum without making any linearizing assumption or simplification. The algorithm mimics the natural evolutionary processes of selection, crossover and mutation and, minimizes a composite misfit function for searching the global optimum, the fittest stress tensor. The validity and efficacy of the algorithm are demonstrated by a series of tests on synthetic and natural fault-slip observations in different tectonic settings and also in situations where the observations are noisy. It is shown that the genetic algorithm is superior to other commonly practised methods, in particular, in those tectonic settings where none of the principal stresses is directed vertically and/or the given data set is noisy.

Metamorphic reprocessing of a serpentinized carbonate-bearing peridotite after detachment from the mantle wedge: A P-T path constrained from textures and phase diagrams in the system CaO-MgO-Al 2O 3-SiO 2-CO 2-H 2O

NASA Astrophysics Data System (ADS)

Mposkos, E.; Baziotis, I.; Proyer, A.

2010-08-01

In the central Rhodope mountains of Greece a carbonate-bearing metaperidotite lens ˜ 200 × 500 m in size crops out as part of the high- to ultrahigh-pressure metamorphic Upper Sidironero Complex ˜ 500 m SE of the Gorgona Village, north of Xanthi town. It is composed primarily of coarse grained (3-20 mm in size) olivine and orthopyroxene, medium grained clinohumite and medium to fine grained tremolite, chlorite, dolomite, magnesite, talc, antigorite and various spinel phases. Whole-rock chemistry, mineral textures and compositions, and phase diagram calculations show that the metaperidotite was subjected to a prograde HP metamorphism, isofacial with the surrounding migmatitic gneisses, metapelites and amphibolites. The prograde character of metamorphism is demonstrated by inclusions of talc, antigorite, chlorite, dolomite, magnesite and Ti-clinohumite in ferrit-chromite, olivine, and orthopyroxene, as well as of olivine in orthopyroxene, and by the typical change in composition of zoned spinel minerals from ferrit-chromite in the core to chromian spinel at the rim. The prograde path is characterized by successive growth of amphibole, Ti-clinohumite, olivine and orthopyroxene, followed by the breakdown of Ti-clinohumite to olivine + Mg-ilmenite and of chlorite to olivine + spinel, probably during exhumation. The construction of a partial petrogenetic P- T grid in the system CaO-MgO-Al 2O 3-SiO 2-CO 2-H 2O (CMASCH) for Ca-poor ultramafic bulk compositions has proven highly useful for the reconstruction of the metamorphic evolution and a P- T path, indicating that the use of univariant reactions in mixed volatile systems is highly warranted. The P- T path is clearly constrained to pressures below 1.5-1.7 GPa by the absence of clinopyroxene. These pressures are slightly lower than those recorded in the closely associated Jurassic eclogites and much lower than those recorded in the diamond-bearing gneisses 5 km to the south in the same tectonic unit. The carbonate-bearing metaperidotite from Gorgona probably represents a fragment of the hydrated mantle wedge. This is indicated by the REE compositions which differ from those of ophiolitic peridotites and resemble those of spinel or garnet peridotites of sub-continental origin. The ultramafic slice was incorporated tectonically into the subduction channel, most likely by tectonic erosion in the Early Jurassic, but did not experience ultrahigh-pressure metamorphism like the nearby metapelites that exhumed along the same subduction channel.

Seismological and structural constraints on the 2011-2013, Mmax 4.6 seismic sequence at the south-eastern edge of the Calabrian arc (North-eastern Sicily, Italy)

NASA Astrophysics Data System (ADS)

Cammarata, Laura; Catalano, Stefano; Gambino, Salvatore; Palano, Mimmo; Pavano, Francesco; Romagnoli, Gino; Scaltrito, Antonio; Tortorici, Giuseppe

2018-01-01

Between June 2011 and September 2013, the Nebrodi Mountains region was affected by a seismic swarm consisting of > 2700 events with local magnitude 1.3 ≤ ML ≤ 4.6 and located in the 5-9 km depth interval. The seismic swarm defines a seismogenetic volume elongated along the E-W direction and encompasses the NW-SE-oriented tectonic boundary between the Calabrian arc (north-eastward) and the Sicilide units (south-westward). By exploring the recent tectonic deformation and the seismic behavior of the region, this study aims at providing additional constraints on the seismogenetic faults at the southern termination of the Calabrian arc. Waveform similarities analysis allowed observing that 45% of the whole dataset can be grouped into six different families of seismic events. Earthquake multiplet families are mainly located in the eastern part of the seismogenetic volume. We suggest that such a feature is responsive to the lateral lithological variations as highlighted by geology (at the surface) and P-wave seismic tomography (at depth of 10 km). Stress tensor inversions performed on FPSs indicate that the investigated region is currently subject to a nearly biaxial stress state in an extensional regime, such that crustal stretching occurs along both NW-SE and NE-SW directions. Accordingly, mesoscale fault geometries and kinematics analyses evidence that a younger normal faulting stress regime led to a tectonic negative inversion by replacing the pre-existing strike-slip one. Based on our results and findings reported in recent literature, we refer such a crustal stretching to mantle upwelling process (as evidenced by diffuse mantle-derived gas emissions) coupled with a tectonic uplift involving north-eastern Sicily since Middle Pleistocene. Moreover, seismic swarms striking the region would be related to the migration of mantle and sub-crustal fluids toward the surface along the complex network of tectonic structures cutting the crust and acting as pathways.

In search of transient subduction interfaces in the Dent Blanche-Sesia Tectonic System (W. Alps)

NASA Astrophysics Data System (ADS)

Angiboust, Samuel; Glodny, Johannes; Oncken, Onno; Chopin, Christian

2014-09-01

In this paper we study the Alpine metamorphic history of a major tectonic zone which formed during Alpine orogeny, the Dent Blanche Thrust (DBT). This contact, located in the Northern Western Alps, juxtaposes some ophiolitic metasediment-rich remnants of the Liguro-Piemontese ocean (Tsaté Complex) with a composite continental, km-sized complex (Dent Blanche Tectonic System, DBTS) of Adriatic affinity thrusted over the ophiolite. In order to better understand the geodynamic meaning of the DBT region and adjacent units, we have reconstructed the pressure-temperature-time-deformation (P-T-t-d) history of these two units using modern thermobarometric tools, Rb/Sr geochronology, and field relationships. We show that the Tsaté Complex is formed by a stack of km-thick calcschists-bearing tectonic slices having experienced variable maximum burial temperatures between 360 °C and 490 °C at depths of ca. 25-40 km. Associated deformation ages span a range between 37 Ma and 41 Ma. The Arolla gneissic mylonites at the base of the DBTS experienced high-pressure (12-14 kbar), top-to-NW deformation at ca. 450 °C between 43 and 48 Ma. A first age of ca. 58 Ma has been obtained for high-pressure ductile deformation in the Valpelline shear zone, atop Arolla gneisses. Some of the primary, peak metamorphic fabrics have been reworked and later backfolded during exhumation and collisional overprint (ca. 20 km depth, 37-40 Ma) leading to the regional greenschist-facies retrogression which is particularly prominent within Tsaté metasediments. We interpret the Dent Blanche Thrust, at the base of the Arolla unit, as a fossilized subduction interface active between 43 and 48 Ma. Our geochronological results on the shear zone lining the top of the Arolla unit, together with previous P-T-t estimates on equivalent blueschist-facies shear zones cutting the Sesia unit, indicate an older tectonic activity between 58 and 65 Ma. We demonstrate here that observed younger ages towards lowermost structural levels are witness of the transient, downwards migration of the Alpine early Cenozoic blueschist-facies subduction interface. This down-stepping is interpreted to reflect the progressive underplating acting between 30 and 40 km depth in the Alpine subduction zone between late Cretaceous and late Eocene. Underplating involved first continental material derived from the stretched Adriatic margin followed by underplating of ocean-derived rocks in the Eocene. These results shed light on subduction-zone accretion processes and therefore provide a new perspective for the understanding of geophysical results imaging the plate-interface region in active subduction zones.

Study of complex permittivity spectra of binary mixtures of 2-chloroaniline and methanol in frequency range 10 KHz to 2 MHz at different temperatures

NASA Astrophysics Data System (ADS)

Shah, N. S.; Vankar, H. P.; Rana, V. A.

2017-05-01

The complex relative dielectric function ɛ*(ω)=ɛ'-jɛ″ of the binary mixture of 2-chloroaniline(2-CA) and methanol (MeOH) were measured using precision LCR meter in the frequency range of 10 KHz to 2 MHz The measurements were carried out at eight different temperatures and five different concentrations of 2-CA and MeOH. The loss tangent peaks were observed in the studied frequency range for all the binary mixtures. From the loss tangent peaks electrode polarization relaxation time were evaluated. In the plot of real part of complex permittivity against frequency, at different temperatures for 2-CA (54.54%) + MeOH (45.45%) and 2-CA (27.27%) + MeOH (72.72%)and 100% MeOH systems permittivity inversion effect was observed.

Ordovician magmatism in the Lévézou massif (French Massif Central): tectonic and geodynamic implications

NASA Astrophysics Data System (ADS)

Lotout, Caroline; Pitra, Pavel; Poujol, Marc; Van Den Driessche, Jean

2017-03-01

New U-Pb dating on zircon yielded ca. 470 Ma ages for the granitoids from the Lévézou massif in the southern French Massif Central. These new ages do not support the previous interpretation of these granitoids as syn-tectonic intrusions emplaced during the Late Devonian-Early Carboniferous thrusting. The geochemical and isotopic nature of this magmatism is linked to a major magmatic Ordovician event recorded throughout the European Variscan belt and related to extreme thinning of continental margins during a rifting event or a back-arc extension. The comparable isotopic signatures of these granitoids on each side of the eclogite-bearing leptyno-amphibolitic complex in the Lévézou massif, together with the fact that they were emplaced at the same time, strongly suggest that these granitoids were originally part of a single unit, tectonically duplicated by either isoclinal folding or thrusting during the Variscan tectonics.

The metamorphic record of subduction-accretion processes in the Neoarchaean: the Nuuk region, southern West Greenland.

NASA Astrophysics Data System (ADS)

Dziggel, Annika; Kolb, Jochen

2013-04-01

The Nuuk region of southern West Greenland exposes an exceptionally well preserved section through Archaean mid- to lower continental crust, and therefore provides a natural laboratory to study the tectonic processes in the Archaean. The area mainly consists of amphibolite to granulite facies TTG gneisses, narrow supracrustal belts, and minor late-tectonic granites. It is made up of several distinct terranes, including, from NW to SE, the Færingehavn, Tre Brødre, and Tasiusarsuaq terranes. Extensive high-grade metamorphism and a clockwise PT evolution of the Færingehavn terrane in the Neoarchaean (2.72-2.71 Ga) have been interpreted as a result of crustal thickening and thrusting of the Tasiusarsuaq terrane on top of the Tre Brødre and Færingehavn terranes (Nutman and Friend, 2007). Prior to final collision, the Tasiusarsuaq terrane (the upper plate in a plate tectonic model) underwent a prolonged period of compressive deformation between 2.8 and 2.72 Ga (Kolb et al., 2012). The structural evolution was associated with near-isobaric cooling from medium-pressure granulite facies conditions of ca. 850°C and 7.5 kbar to amphibolite facies conditions of ca. 700°C and 6.5-7 kbar (Dziggel et al., 2012). Despite this long period of crustal convergence, there is no evidence for exhumation and/or loading, pointing to a rheologically weak and unstable Archaean crust perhaps due to low density differences and ongoing melt extraction. Rocks of the structurally underlying Færingehavn terrane record a distinctly different metamorphic evolution. Although generally more strongly retrogressed, relict higher-pressure mineral assemblages in mafic granulites and felsic gneisses record conditions of > 8-9 kbar and >= 750°C, indicating burial to depths of at least 30 km along an apparent geothermal gradient of 20-25°C/km. The peak of metamorphism was followed by isothermal decompression at ca. 2.715 Ga (Nutman and Friend, 2007), indicating rapid exhumation of lower crustal rocks during, or shortly after, the main accretionary event. The existence of dual thermal regimes with contrasting PT paths, as well as the good correlation between the timing of collision, high-pressure metamorphism and rapid exhumation are all consistent with plate-tectonic processes operating in the Neoarchaean. However, the crustal convergence in the Nuuk region was not associated with the extreme crustal thickening observed in many younger orogenic belts, and this likely reflects the generally higher mantle temperatures in the Neoarchaean. The prolonged period of crustal convergence prior to final collision may further indicate that the convergence rates in the Archaean were rather low. Dziggel, A., Diener, J.F.A., Stoltz, N.B., Kolb, J., 2012. Role of H2O in the formation of garnet coronas during near-isobaric cooling of mafic granulites: the Tasiusarsuaq terrane, southern West Greenland. Journal of Metamorphic Geology, 30, 957-972. Kolb, J., Kokfelt, T.F., Dziggel, A., 2012. Geodynamic setting and deformation history of an Archaean terrane at mid-crustal level: the Tasiusarsuaq terrane of southern West Greenland. Precambrian Research, 212-213, 34-56. Nutman, A.P. & Friend, C.R.L., 2007. Adjacent terranes with ca. 2715 and 2650 Ma high-pressure metamorphic assemblages in the Nuuk region of the North Atlantic Craton, southern West Greenland: Complexities of Neoarchaean collisional orogeny. Precambrian Research, 155, 159-203.

Relationship between deep structure and oil-gas in the eastern Tarim Basin

NASA Astrophysics Data System (ADS)

Yu, Changqing; Qu, Chen; Han, Jianguang

2017-04-01

The Tarim Basin is a large composite superimposed basin which developed in the Presinian continental basement. It is an important area for oil and gas replacement in China. In the eastern part of Tarim Basin, the exploration and research degree is very low and less system, especially in the study of tectonic evolution and physical property change. Basing on the study of geophysics, drilling and regional geological data in this area, analysis of comprehensive geophysical, geological and geophysical analysis comparison are lunched by new methods and new technology of geophysical exploration. Fault, tectonic evolution and change of deep character in the eastern Tarim Basin are analyzed in system. Through in-depth study and understanding of the deep structure and physical changes of the eastern region, we obtain the fault characteristics in the study area and the deep structure and physical change maps to better guide the oil and gas exploration in this area. The east area is located in the eastern Tarim Basin, west from the Garr Man depression, Well Kunan 1 - Well Gucheng 4 line to the East, north to Kuruketage uplift group near Qunke 1 wells, south to Cherchen fault zone, east to Lop Nor depression, an area of about 9 * 104 square kilometres, Including the East of Garr Man sag, Yingjisu depression, Kongquehe slope, Tadong low uplift and the Lop Nor uplift, five two grade tectonic units. The east area of Tarim is belonging to Tarim plate. It changes with the evolution of the Tarim plate. The Tarim plate is closely related to the collision between the Yining - the Junggar plate, the Siberia plate and the southern Qiangtang - the central Kunlun plate. Therefore, it creates a complex tectonic pattern in the eastern Tarim basin. Earth electromagnetic, gravity, deep seismic and other geophysical data are processed by a new generation of geophysical information theory and method, including multi-scale inversion of potential field inversion (Hou and Yang, 2011), 3D magnetotelluric data (Yang et al., 2012) and micro seismic wave field information recognition technology in the eastern Tarim Basin. Combining the information of the deep faults, tectonic evolution characteristics of the study area and the physical changes from geological data, we analyze the relationship between the change of the physical structure and the oil and gas, and predict the favorable oil and gas area and the exploration target area by information extraction, processing and interpretation analysis based on integrated geophysical technology. References 1. Hou, Z. Z., W. C. Yang, 2011, multi scale gravity field inversion and density structure in Tarim Basin: Chinese science, 41, 29-39. 2. Yang W. C., J. L. Wang, H. Z. Zhong, 2012, The main port of the Tarim Basin Analysis of magnetic field and magnetic source structure: Chinese Journal of Geophysics, 55, 1278-1287.

Structural evolution and tectonic context of the Mfongosi Group, Natal thrust front, Tugela terrane, South Africa

NASA Astrophysics Data System (ADS)

Basson, I. J.; Watkeys, M. K.; Phillips, D.

2005-11-01

The Mesoproterozoic Natal Metamorphic Province of Kwazulu-Natal in South Africa is an assemblage of several tectonic units, including accreted oceanic island arcs, obducted oceanic crust and deformed basin material. The highly deformed Mfongosi Group occurs at the leading edge of collision (the Natal thrust front), against and directly overlying the southern margin of the Kaapvaal Craton. Structures within the Mfongosi Group record "local" D1 and D2 events, the first of which was "oblique obduction", with predominantly N- to NNE-verging thrusting ( D1). This was followed by sinistral transpression combined with vertical constriction, forming SW-plunging kink folds and SW-plunging prolate pillow basalts ( D2). The third and final event ( D3) was E-W to ESE-WNW extension in a post-thrusting phase, defined by fibrous antitaxial quartz-calcite veining. The westernmost portion of the Mfongosi Group, the Ngubevu area, shows significantly higher finite strains (up to Rf = 12) compared to central Mfongosi and eastern Nkandlha areas ( Rf = 1.5 and less), suggesting highly oblique, largely NE-directed initial collision. Deformation of the NTF in the context of nappe emplacement is constrained by 40Ar/ 39Ar dating of post-cataclastic nematoblastic/porphyroblastic hornblende of the Manyane amphibolite close to the thrust between the Tugela nappe and the Mfongosi Group in the Mfongosi area. Hornblende overgrew the products of low-temperature deformation during the "local" D1 and D2. A minimum age of 1171 ± 16 Ma (95% conf., including J-error; weighted by √MSWD; MSWD = 4.3) is obtained for the tectonic juxtaposition of the Tugela nappe against the southern portions of the "Mfongosi Basin". This "local" D1 and D2 of the Mfongosi Group pre-dates the regional "oblique D1" and "left-lateral D2" previously determined for the central and southern terranes of the Natal Metamorphic Province by other researchers. Comparison of the 1171 ± 16 Ma age, with ages for shearing and intrusion, suggests that thrusting and/or mylonite-forming events migrated southwards throughout the Natal Metamorphic Province, being separated by approximately 25 million years. Thrusting and/or mylonite-forming events occurred in the nappe zone from ca. 1135 Ma to 1077 Ma, followed by a period of "quiescence" during which granites intruded, in turn followed by late-tectonic deformation of the southern Mzumbe and Margate terranes from ca. 1004 Ma to 970 Ma. Such a scenario supports previously-proposed indentation models with their implications of oblique convergence and late-tectonic escape of island arcs to the E/ENE (African azimuths).

Tectonic Constraints on the Evolution of Geothermal Systems in the Central Andean Volcanic Zone (CAVZ)

NASA Astrophysics Data System (ADS)

Veloso, E. E.; Tardani, D.; Aron, F.; Elizalde, J. D.; Sanchez-Alfaro, P.; Godoy, B.

2017-12-01

South of 19°S, geothermal fields and Pliocene-to-Holocene volcanic centers of the Central Andean Volcanic Zone are spatially associated with distinct, large-scale fault systems disrupting the volcanic arc, which control the architecture and dynamics of the fluids reservoirs at shallow crustal levels. Based on an extensive compilation of structural, lithological and isotopic data, and satellite imagery band-ratio analyses, we produced detailed maps of 13 areas comprising 19 identified and/or potential geothermal fields, to examine if particular local-scale tectonic configurations are associated to fluids migrating from different crustal levels. We defined three main tectonic environments according to the specific, kilometer-scale structural arrangement and its spatial relation to the geothermal surface manifestations. T1, dominated by left-lateral, pure strike-slip motion on a NW-trending duplex-like geometry with geothermal fields located along the faults - in turn distributed into five major subparallel zones cutting across the orogenic belt between ca. 20° and 27°S. T2, dominated by shortening on a series of N-trending thrust faults and fault-propagated folds, cut and displaced by the above mentioned NW-trending faults, with geothermal fields hosted at fault intersections and at fold hinges. And T3, characterized by transtension accommodated by NW-to-WNW-trending left-lateral/normal faults, with hot-springs lying along the fault traces. Interestingly, each of the independently defined tectonic environments has distinctive helium (in fluids) and strontium (in lavas) isotopic signatures and estimated geothermal reservoir temperatures. T1 shows a large 4He contribution, low 87Sr/86Sr ratio and temperatures varying between ca. 220°-310°C; T3 low 4He and high 87Sr/86Sr ratio and temperature (260°-320°C); T2 isotopic values fall between T1 and T3, yet showing the lowest (130°-250°C) temperatures. We suggest that these particular isotopic signatures are due to a strong structural control on the hot reservoir location and meteoric water content, T3 allowing deeper hot fluid provenances and T1 more meteoric influx.

Late Neoproterozoic to Carboniferous genesis of A-type magmas in Avalonia of northern Nova Scotia: repeated partial melting of anhydrous lower crust in contrasting tectonic environments

NASA Astrophysics Data System (ADS)

Murphy, J. Brendan; Shellnutt, J. Gregory; Collins, William J.

2018-03-01

Avalonian rocks in northern mainland Nova Scotia are characterized by voluminous 640-600 Ma calc-alkalic to tholeiitic mafic to felsic magmas produced in a volcanic arc. However, after the cessation of arc activity, repeated episodes of felsic magmatism between ca. 580 Ma and 350 Ma are dominated by A-type geochemical characteristics. Sm-Nd isotopic data, combined with zircon saturation temperature estimates, indicate that these magmas were formed by high temperature (800-1050 °C) melting of the same anhydrous crustal source. Regional tectonic considerations indicate that A-type felsic magmatism was produced (1) at 580 Ma in a San Andreas-type strike slip setting, (2) at 495 Ma as Avalonia rifted off Gondwana, (3) at 465 and 455 in an ensialic island arc environment and (4) at 360-350 Ma during post-collisional, intra-continental strike-slip activity as Avalonia was translated dextrally along the Laurentian margin. These results attest to the importance of crustal source, rather than tectonic setting, in the generation of these A-type magmas and are an example of how additional insights are provided by comparing the geochemical and isotopic characteristics of igneous suites of different ages within the same terrane. They also suggest that the shallow crustal rocks in northern mainland Nova Scotia were not significantly detached from their lower crustal source between ca. 620 Ma and 350 Ma, a time interval that includes the separation of Avalonia from Gondwana, its drift and accretion to Laurentia as well as post-accretionary strike-slip displacement.

Calcium sources used by post-natal human myoblasts during initial differentiation.

PubMed

Arnaudeau, Serge; Holzer, Nicolas; König, Stéphane; Bader, Charles R; Bernheim, Laurent

2006-08-01

Increases in cytoplasmic Ca(2+) are crucial for inducing the initial steps of myoblast differentiation that ultimately lead to fusion; yet the mechanisms that produce this elevated Ca(2+) have not been fully resolved. For example, it is still unclear whether the increase comes exclusively from membrane Ca(2+) influx or also from Ca(2+) release from internal stores. To address this, we investigated early differentiation of myoblast clones each derived from single post-natal human satellite cells. Initial differentiation was assayed by immunostaining myonuclei for the transcription factor MEF2. When Ca(2+) influx was eliminated by using low external Ca(2+) media, we found that approximately half the clones could still differentiate. Of the clones that required influx of external Ca(2+), most clones used T-type Ca(2+) channels, but others used store-operated channels as influx-generating mechanisms. On the other hand, clones that differentiated in low external Ca(2+) relied on Ca(2+) release from internal stores through IP(3) receptors. Interestingly, by following clones over time, we observed that some switched their preferred Ca(2+) source: clones that initially used calcium release from internal stores to differentiate later required Ca(2+) influx and inversely. In conclusion, we show that human myoblasts can use three alternative mechanisms to increase cytoplasmic Ca(2+) at the onset of the differentiation process: influx through T-types Ca(2+) channels, influx through store operated channels and release from internal stores through IP(3) receptors. In addition, we suggest that, probably because Ca(2+) elevation is essential during initial differentiation, myoblasts may be able to select between these alternate Ca(2+) pathways.

Quantification of Uncertainty in Full-Waveform Moment Tensor Inversion for Regional Seismicity

NASA Astrophysics Data System (ADS)

Jian, P.; Hung, S.; Tseng, T.

2013-12-01

Routinely and instantaneously determined moment tensor solutions deliver basic information for investigating faulting nature of earthquakes and regional tectonic structure. The accuracy of full-waveform moment tensor inversion mostly relies on azimuthal coverage of stations, data quality and previously known earth's structure (i.e., impulse responses or Green's functions). However, intrinsically imperfect station distribution, noise-contaminated waveform records and uncertain earth structure can often result in large deviations of the retrieved source parameters from the true ones, which prohibits the use of routinely reported earthquake catalogs for further structural and tectonic interferences. Duputel et al. (2012) first systematically addressed the significance of statistical uncertainty estimation in earthquake source inversion and exemplified that the data covariance matrix, if prescribed properly to account for data dependence and uncertainty due to incomplete and erroneous data and hypocenter mislocation, cannot only be mapped onto the uncertainty estimate of resulting source parameters, but it also aids obtaining more stable and reliable results. Over the past decade, BATS (Broadband Array in Taiwan for Seismology) has steadily devoted to building up a database of good-quality centroid moment tensor (CMT) solutions for moderate to large magnitude earthquakes that occurred in Taiwan area. Because of the lack of the uncertainty quantification and reliability analysis, it remains controversial to use the reported CMT catalog directly for further investigation of regional tectonics, near-source strong ground motions, and seismic hazard assessment. In this study, we develop a statistical procedure to make quantitative and reliable estimates of uncertainty in regional full-waveform CMT inversion. The linearized inversion scheme adapting efficient estimation of the covariance matrices associated with oversampled noisy waveform data and errors of biased centroid positions is implemented and inspected for improving source parameter determination of regional seismicity in Taiwan. Synthetic inversion tests demonstrate the resolved moment tensors would better match the hypothetical CMT solutions, and tend to suppress unreal non-double-couple components and reduce the trade-off between focal mechanism and centroid depth if individual signal-to-noise ratios and correlation lengths for 3-component seismograms at each station and mislocation uncertainties are properly taken into account. We further testify the capability of our scheme in retrieving the robust CMT information for mid-sized (Mw~3.5) and offshore earthquakes in Taiwan, which offers immediate and broad applications in detailed modelling of regional stress field and deformation pattern and mapping of subsurface velocity structures.

Carotenoid Intake and Adipose Tissue Carotenoid Levels in Relation to Prostate Cancer Aggressiveness among African-American and European-American Men in the North Carolina-Louisiana Prostate Cancer Project (PCaP)

PubMed Central

Antwi, Samuel O.; Steck, Susan E.; Su, L. Joseph; Hebert, James R.; Zhang, Hongmei; Craft, Neal E.; Fontham, Elizabeth T. H.; Smith, Gary J.; Bensen, Jeannette T.; Mohler, James L.; Arab, Lenore

2016-01-01

Background Associations between carotenoid intake and prostate cancer (CaP) incidence have varied across studies. This may be due to combining indolent with aggressive disease in most studies. This study examined whether carotenoid intake and adipose tissue carotenoid levels were inversely associated with CaP aggressiveness. Methods Data on African-American (AA, n=1,023) and European-American (EA, n=1,079) men with incident CaP from North Carolina and Louisiana were analyzed. Dietary carotenoid intake was assessed using a detailed food frequency questionnaire, and abdominal adipose tissue samples were analyzed for carotenoid concentrations using high-performance liquid chromatography. Multivariable logistic regression was used in race-stratified analysis to calculate odds ratios (ORs) and 95% confidence intervals (95%CI) comparing high aggressive CaP with low/intermediate aggressive CaP. Results Carotenoid intake differed significantly between AAs and EAs, which included higher intake of lycopene among EAs and higher β–cryptoxanthin intake among AAs. Comparing the highest and lowest tertiles, dietary lycopene was associated inversely with high aggressive CaP among EAs (OR=0.55, 95%CI: 0.34–0.89, Ptrend=0.02), while an inverse association was observed between dietary β–cryptoxanthin intake and high aggressive CaP among AAs (OR=0.56, 95%CI: 0.36–0.87, Ptrend=0.01). Adipose tissue α–carotene and lycopene (cis + trans) concentrations were higher among EAs than AAs, and marginally significant inverse linear trends were observed for adipose α–carotene (Ptrend=0.07) and lycopene (Ptrend=0.11), and CaP aggressiveness among EAs only. Conclusions These results suggest that diets high in lycopene and β–cryptoxanthin may protect against aggressive CaP among EAs and AAs, respectively. Differences in dietary behaviors may explain the racial differences in associations. PMID:27271547

Martian plate tectonics

NASA Astrophysics Data System (ADS)

Sleep, N. H.

1994-03-01

The northern lowlands of Mars have been produced by plate tectonics. Preexisting old thick highland crust was subducted, while seafloor spreading produced thin lowland crust during late Noachian and Early Hesperian time. In the preferred reconstruction, a breakup margin extended north of Cimmeria Terra between Daedalia Planum and Isidis Planitia where the highland-lowland transition is relatively simple. South dipping subduction occured beneath Arabia Terra and east dipping subduction beneath Tharsis Montes and Tempe Terra. Lineations associated with Gordii Dorsum are attributed to ridge-parallel structures, while Phelegra Montes and Scandia Colles are interpreted as transfer-parallel structures or ridge-fault-fault triple junction tracks. Other than for these few features, there is little topographic roughness in the lowlands. Seafloor spreading, if it occurred, must have been relatively rapid. Quantitative estimates of spreading rate are obtained by considering the physics of seafloor spreading in the lower (approx. 0.4 g) gravity of Mars, the absence of vertical scarps from age differences across fracture zones, and the smooth axial topography. Crustal thickness at a given potential temperature in the mantle source region scales inversely with gravity. Thus, the velocity of the rough-smooth transition for axial topography also scales inversely with gravity. Plate reorganizations where young crust becomes difficult to subduct are another constraint on spreading age. Plate tectonics, if it occurred, dominated the thermal and stress history of the planet. A geochemical implication is that the lower gravity of Mars allows deeper hydrothermal circulation through cracks and hence more hydration of oceanic crust so that more water is easily subducted than on the Earth. Age and structural relationships from photogeology as well as median wavelength gravity anomalies across the now dead breakup and subduction margins are the data most likely to test and modify hypotheses about Mars plate tectonics.

Late Jurassic-Early Cretaceous continental convergence and intracontinental orogenesis in East Asia: A synthesis of the Yanshan Revolution

NASA Astrophysics Data System (ADS)

Dong, Shuwen; Zhang, Yueqiao; Zhang, Fuqin; Cui, Jianjun; Chen, Xuanhua; Zhang, Shuanhong; Miao, Laicheng; Li, Jianhua; Shi, Wei; Li, Zhenhong; Huang, Shiqi; Li, Hailong

2015-12-01

The basic tectonic framework of continental East Asia was produced by a series of nearly contemporaneous orogenic events in the late Middle Jurassic to Early Cretaceous. Commonly, the Late Mesozoic orogenic processes were characterized by continent-continent collision, large-scale thrusting, strike-slip faulting and intense crustal shortening, crustal thickening, regional anatexis and metamorphism, followed by large-scale lithospheric extension, rifting and magmatism. To better understand the geological processes, this paper reviews and synthesizes existing multi-disciplinary geologic data related to sedimentation, tectonics, magmatism, metamorphism and geochemistry, and proposes a two-stage tectono-thermal evolutionary history of East Asia during the late Middle Jurassic to Early Cretaceous (ca. 170-120 Ma). In the first stage, three orogenic belts along the continental margins were formed coevally at ca. 170-135 Ma, i.e., the north Mongol-Okhotsk orogen, the east paleo-Pacific coastal orogen, and the west Bangong-Nujiang orogen. Tectonism related to the coastal orogen caused extensive intracontinental folding and thrusting that resulted in a depositional hiatus in the Late Jurassic, as well as crustal anatexis that generated syn-kinematic granites, adakites and migmatites. The lithosphere of the East Asian continent was thickened, reaching a maximum during the latest Jurassic or the earliest Cretaceous. In the second stage (ca. 135-120 Ma), delamination of the thickened lithosphere resulted in a remarkable (>120 km) lithospheric thinning and the development of mantle-derived magmatism, mineralization, metamorphic core complexes and rift basins. The Middle Jurassic-Early Cretaceous subduction of oceanic plates (paleo-Pacific, meso-Tethys, and Mongol-Okhotsk) and continent-continent collision (e.g. Lhasa and Qiangtang) along the East Asian continental margins produced broad coastal and intracontinental orogens. These significant tectonic activities, marked by widespread intracontinental orogeny and continental reconstruction, are commonly termed the Yanshan Revolution (Movement) in the Chinese literature.

Improper magnetic ferroelectricity of nearly pure electronic nature in helicoidal spiral CaMn7O12

NASA Astrophysics Data System (ADS)

Lim, Jin Soo; Saldana-Greco, Diomedes; Rappe, Andrew M.

2018-01-01

Helicoidal magnetic order breaks inversion symmetry in quadruple perovskite CaMn7O12 , generating one of the largest spin-induced ferroelectric polarizations measured to date. Here, the microscopic origin of the polarization, including exchange interactions, coupling to the spin helicity, and charge density redistribution, is explored via first-principles calculations. The B -site Mn4 + (Mn3) spin adopts a noncentrosymmetric configuration, stabilized not only by spin-orbit coupling (SOC), but also by the fully anisotropic Hubbard J parameter in the absence of SOC, to break inversion symmetry and generate polarization. Berry phase computed polarization (Pelec=2169 μ C /m2 ) exhibits nearly pure electronic behavior, with negligible Mn displacements (≈0.7 m Å ). Orbital-resolved density of states shows that p -d orbital mixing is microscopically driven by nonrelativistic exchange striction within the commensurate ionic structure. Persistent electronic polarization induced by helical spin order in the nearly inversion-symmetric ionic crystal lattice suggests opportunities for ultrafast magnetoelectric response.

Electrical and Ca2+ signaling in dendritic spines of substantia nigra dopaminergic neurons

PubMed Central

Hage, Travis A; Sun, Yujie; Khaliq, Zayd M

2016-01-01

Little is known about the density and function of dendritic spines on midbrain dopamine neurons, or the relative contribution of spine and shaft synapses to excitability. Using Ca2+ imaging, glutamate uncaging, fluorescence recovery after photobleaching and transgenic mice expressing labeled PSD-95, we comparatively analyzed electrical and Ca2+ signaling in spines and shaft synapses of dopamine neurons. Dendritic spines were present on dopaminergic neurons at low densities in live and fixed tissue. Uncaging-evoked potential amplitudes correlated inversely with spine length but positively with the presence of PSD-95. Spine Ca2+ signals were less sensitive to hyperpolarization than shaft synapses, suggesting amplification of spine head voltages. Lastly, activating spines during pacemaking, we observed an unexpected enhancement of spine Ca2+ midway throughout the spike cycle, likely involving recruitment of NMDA receptors and voltage-gated conductances. These results demonstrate functionality of spines in dopamine neurons and reveal a novel modulation of spine Ca2+ signaling during pacemaking. DOI: http://dx.doi.org/10.7554/eLife.13905.001 PMID:27163179

Prolonged episodic Paleoproterozoic metamorphism in the Thelon Tectonic Zone, Canada: an in-situ SHRIMP/EPMA monazite geochronology study

NASA Astrophysics Data System (ADS)

Mitchell, Rhea; William, Davis; Robert, Berman; Sharon, Carr; Michael, Jercinovic

2017-04-01

The Thelon Tectonic zone (TTZ), Nunavut, Canada, is a >500km long geophysically, lithologically and structurally distinct N-NNE striking Paleoproterozoic boundary zone between the Slave and Rae Archean provinces. The TTZ has been interpreted as a ca. 2.0 Ga continental arc on the western edge of the Rae craton, that was deformed during collision with the Slave craton ca. 1.97 Ga. Alternatively, the Slave-Rae collision is interpreted as occurring during the 2.35 Ga Arrowsmith orogeny while the 1.9-2.0 Ga TTZ represents an intra-continental orogenic belt formed in previously thinned continental crust, postdating the Slave-Rae collision. The central part of the TTZ comprises three >100 km long, 10-20 km wide belts of ca. 2.0 Ga, mainly charnockitic plutonic rocks, and a ca. 1910 Ma garnet-leucogranite belt. Metamorphism throughout these domains is upper-amphibolite to granulite-facies, with metasedimentary rocks occurring as volumetrically minor enclaves and strands of migmatites. The Ellice River domain occurs between the western and central plutonic belts. It contains ca. 1950 Ma ultramafic to dacitic volcanic rocks and foliated Paleoproterozoic psammitic metasedimentary rocks at relatively lower grade with lower to middle amphibolite-facies metamorphic assemblages. In-situ U-Pb analyses of monazite using a combination of Sensitive High-Resolution Ion Microprobe (SHRIMP) and Electron Probe Microanalyzer (EPMA) were carried out on high-grade metasedimentary rocks from seventeen samples representing the eastern margin of the Slave Province and all major lithological domains of the TTZ. 207Pb/206Pb monazite ages from SHRIMP analysis form the foundation of this dataset, while EPMA ages are supplementary. The smaller <6µm spot size of EPMA allowed for further constraint on ages of micro-scale intra-crystalline domains in some samples. Monazite ages define four distinct Paleoproterozoic metamorphic events and one Archean metamorphic event at ca. 2580 Ma. The latter is recorded exclusively along the eastern margin of the Slave Province. Metamorphism ca. 1996 Ma, recorded in one high-grade gneiss from the central plutonic belt appears to reflect a regional contact metamorphism associated with intrusion of 2000 Ma plutons. Throughout the TTZ, a selection of monazite grains included in garnet porphyroblasts define a metamorphic event ca. 1962 Ma. One sample from the eastern margin of the Slave Province similarly records metamorphism at 1961 Ma in monazite grains in the matrix. This sample interestingly does not record the ca. 2580 Ma metamorphism typical of the Slave Province. The longest lived and most wide spread metamorphic event in the TTZ occurred ca. 1922 to 1883 Ma. This event is interpreted as the main compressional/collisional and anatectic event, with partial melting forming the extensive ca. 1910 Ma garnet-leucogranite belts. Three samples, located in the eastern margin of the Slave province, the Ellice River domain and the eastern plutonic belt, record younger metamorphism at ca. 1814 Ma. These events may represent post-collisional transpression coeval with movement along nearby regional-scale faults.

Inversion of calcite twin data for paleostress orientations and magnitudes: A new technique tested and calibrated on numerically-generated and natural data

NASA Astrophysics Data System (ADS)

Parlangeau, Camille; Lacombe, Olivier; Schueller, Sylvie; Daniel, Jean-Marc

2018-01-01

The inversion of calcite twin data is a powerful tool to reconstruct paleostresses sustained by carbonate rocks during their geological history. Following Etchecopar's (1984) pioneering work, this study presents a new technique for the inversion of calcite twin data that reconstructs the 5 parameters of the deviatoric stress tensors from both monophase and polyphase twin datasets. The uncertainties in the parameters of the stress tensors reconstructed by this new technique are evaluated on numerically-generated datasets. The technique not only reliably defines the 5 parameters of the deviatoric stress tensor, but also reliably separates very close superimposed stress tensors (30° of difference in maximum principal stress orientation or switch between σ3 and σ2 axes). The technique is further shown to be robust to sampling bias and to slight variability in the critical resolved shear stress. Due to our still incomplete knowledge of the evolution of the critical resolved shear stress with grain size, our results show that it is recommended to analyze twin data subsets of homogeneous grain size to minimize possible errors, mainly those concerning differential stress values. The methodological uncertainty in principal stress orientations is about ± 10°; it is about ± 0.1 for the stress ratio. For differential stresses, the uncertainty is lower than ± 30%. Applying the technique to vein samples within Mesozoic limestones from the Monte Nero anticline (northern Apennines, Italy) demonstrates its ability to reliably detect and separate tectonically significant paleostress orientations and magnitudes from naturally deformed polyphase samples, hence to fingerprint the regional paleostresses of interest in tectonic studies.

Post-breakup tectonics in southeast Brazil from thermochronological data and combined inverse-forward thermal history modeling

NASA Astrophysics Data System (ADS)

Cogné, Nathan; Gallagher, Kerry; Cobbold, Peter R.; Riccomini, Claudio; Gautheron, Cecile

2012-11-01

The continental margin of southeast Brazil is elevated. Onshore Tertiary basins and Late Cretaceous/Paleogene intrusions are good evidence for post breakup tectono-magmatic activity. To constrain the impact of post-rift reactivation on the geological history of the area, we carried out a new thermochronological study. Apatite fission track ages range from 60.7 ± 1.9 Ma to 129.3 ± 4.3 Ma, mean track lengths from 11.41 ± 0.23 μm to 14.31 ± 0.24 μm and a subset of the (U-Th)/He ages range from 45.1 ± 1.5 to 122.4 ± 2.5 Ma. Results of inverse thermal history modeling generally support the conclusions from an earlier study for a Late Cretaceous phase of cooling. Around the onshore Taubaté Basin, for a limited number of samples, the first detectable period of cooling occurred during the Early Tertiary. The inferred thermal histories for many samples also imply subsequent reheating followed by Neogene cooling. Given the uncertainty of the inversion results, we did deterministic forward modeling to assess the range of possibilities of this Tertiary part of the thermal history. The evidence for reheating seems to be robust around the Taubaté Basin, but elsewhere the data cannot discriminate between this and a less complex thermal history. However, forward modeling results and geological information support the conclusion that the whole area underwent cooling during the Neogene. The synchronicity of the cooling phases with Andean tectonics and those in NE Brazil leads us to assume a plate-wide compressional stress that reactivated inherited structures. The present-day topographic relief of the margin reflects a contribution from post-breakup reactivation and uplift.

Structural architecture and tectonic evolution of the Maghara inverted basin, Northern Sinai, Egypt

NASA Astrophysics Data System (ADS)

Moustafa, Adel R.

2014-05-01

Large NE-SW oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed Mesozoic and Cenozoic sedimentary rocks of the Maghara area (northern Sinai). Seismic data indicate an earlier Jurassic rifting phase and surface structures indicate Late Cretaceous-Early Tertiary inversion phase. The geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines. Rift-parallel fault segments were reactivated by reverse slip whereas rift-oblique fault segments were reactivated as oblique-slip faults or lateral/oblique ramps. New syn-inversion faults include two short conjugate strike-slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs. Small anticline-syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stauderman, K.A.; Gandhi, V.C.; Jones, D.J.

Fluoxetine, a selective 5-Ht uptake inhibitor, inhibited 15 mM K{sup +}-induced ({sup 3}H)5-HT release from rat spinal cord and cortical synaptosomes at concentrations > 0.5 uM. This effect reflected a property shared by another selective 5-HT uptake inhibitor paroxetine but not by less selective uptake inhibitors such as amitriptyline, desipramine, imipramine or nortriptyline. Inhibition of release by fluoxetine was inversely related to both the concentration of K{sup +} used to depolarize the synaptosomes and the concentration of external Ca{sup 2+}. Experiments aimed at determining a mechanism of action revealed that fluoxetine did not inhibit voltage-independent release of ({sup 3}H)5-HT releasemore » induced by the Ca{sup 2+}-ionophore A 23187 or Ca{sup 2+}-independent release induced by fenfluramine. Moreover the 5-HT autoreceptor antagonist methiothepin did not reverse the inhibitory actions of fluoxetine on K{sup +}-induced release. Further studies examined the effects of fluoxetine on voltage-dependent Ca{sup 2+} channels and Ca{sup 2+} entry.« less

STIM proteins and the endoplasmic reticulum-plasma membrane junctions.

PubMed

Carrasco, Silvia; Meyer, Tobias

2011-01-01

Eukaryotic organelles can interact with each other through stable junctions where the two membranes are kept in close apposition. The junction that connects the endoplasmic reticulum to the plasma membrane (ER-PM junction) is unique in providing a direct communication link between the ER and the PM. In a recently discovered signaling process, STIM (stromal-interacting molecule) proteins sense a drop in ER Ca(2+) levels and directly activate Orai PM Ca(2+) channels across the junction space. In an inverse process, a voltage-gated PM Ca(2+) channel can directly open ER ryanodine-receptor Ca(2+) channels in striated-muscle cells. Although ER-PM junctions were first described 50 years ago, their broad importance in Ca(2+) signaling, as well as in the regulation of cholesterol and phosphatidylinositol lipid transfer, has only recently been realized. Here, we discuss research from different fields to provide a broad perspective on the structures and unique roles of ER-PM junctions in controlling signaling and metabolic processes.

Quantitative analysis of the tectonic subsidence in the Potiguar Basin (NE Brazil)

NASA Astrophysics Data System (ADS)

Lopes, Juliana A. G.; de Castro, David L.; Bertotti, Giovanni

2018-06-01

The Potiguar Basin, located in the Brazilian Equatorial Margin, evolved from a complex rifting process implemented during the Atlantic Ocean opening in the Jurassic/Cretaceous. Different driving mechanisms were responsible for the onset of an aborted onshore rift and an offshore rift that initiated crustal rupture and the formation of a continental transform margin. Therefore, we applied the backstripping method to quantify the tectonic subsidence during the rift and post-rift phases of Potiguar Basin formation and to analyze the spatial variation of subsidence during the two successive and distinct tectonic events responsible for the basin evolution. The parameters required to apply this methodology were extracted from 2D seismic lines and exploratory well data. The tectonic subsidence curves present periods with moderate subsidence rates (up to 300 m/My), which correspond to the evolution of the onshore Potiguar Rift (∼141 to 128 Ma). From 128-118 Ma, the tectonic subsidence curves show no subsidence in the onshore Potiguar Basin, whereas subsidence occurred at high rates (over 300 m/My) in the offshore rift. The post-rift phase began ca. 118 Ma (Aptian), when the tectonic subsidence drastically slowed to less than 35 m/My, probably related to thermal relaxation. The tectonic subsidence rates in the various sectors of the Potiguar Rift, during the different rift phases, indicate that more intense faulting occurred in the southern portion of the onshore rift, along the main border faults, and in the southeastern portion of the offshore rift. During the post-rift phase, the tectonic subsidence rates increased from the onshore portion towards the offshore portion until the continental slope. The highest rates of post-rift subsidence (up to 35 m/My) are concentrated in the central region of the offshore portion and may be related to lithospheric processes related to the continental crust rupture and oceanic seafloor spreading. The variation in subsidence rates and the pattern of tectonic subsidence curves allowed us to interpret the tectonic signature recorded by the sedimentary sequences of the Potiguar Basin during its evolution. In the onshore rift area, the tectonic subsidence curves presented subsidence rates up to 300 m/My during a long-term rift phase (13 Ma), which confirmed that this portion had an extensional tectonic regime. In the offshore rift, the curves presented high subsidence rates of over 300 m/My in a shorter period (5-10 My), typical of basins formed in a transtensional tectonic regime.

Parallel Extension Tectonics (PET): Early Cretaceous tectonic extension of the Eastern Eurasian continent

NASA Astrophysics Data System (ADS)

Liu, Junlai; Ji, Mo; Ni, Jinlong; Guan, Huimei; Shen, Liang

2017-04-01

The present study reports progress of our recent studies on the extensional structures in eastern North China craton and contiguous areas. We focus on characterizing and timing the formation/exhumation of the extensional structures, the Liaonan metamorphic core complex (mcc) and the Dayingzi basin from the Liaodong peninsula, the Queshan mcc, the Wulian mcc and the Zhucheng basin from the Jiaodong peninsula, and the Dashan magmatic dome within the Sulu orogenic belt. Magmatic rocks (either volcanic or plutonic) are ubiquitous in association with the tectonic extension (both syn- and post-kinematic). Evidence for crustal-mantle magma mixing are popular in many syn-kinematic intrusions. Geochemical analysis reveals that basaltic, andesitic to rhyolitic magmas were generated during the tectonic extension. Sr-Nd isotopes of the syn-kinematic magmatic rocks suggest that they were dominantly originated from ancient or juvenile crust partly with mantle signatures. Post-kinematic mafic intrusions with ages from ca. 121 Ma to Cenozoic, however, are of characteristic oceanic island basalts (OIB)-like trace element distribution patterns and relatively depleted radiogenic Sr-Nd isotope compositions. Integrated studies on the extensional structures, geochemical signatures of syn-kinematic magmatic rocks (mostly of granitic) and the tectono-magmatic relationships suggest that extension of the crust and the mantle lithosphere triggered the magmatisms from both the crust and the mantle. The Early Cretaceous tectono-magmatic evolution of the eastern Eurasian continent is governed by the PET in which the tectonic processes is subdivided into two stages, i.e. an early stage of tectonic extension, and a late stage of collapse of the extended lithosphere and transformation of lithospheric mantle. During the early stage, tectonic extension of the lithosphere led to detachment faulting in both the crust and mantle, resulted in the loss of some of the subcontinental roots, gave rise to the exhumation of the mccs, and triggered plutonic emplacement and volcanic eruptions of hybrid magmas. During the late stage, the nature of mantle lithosphere in North China was changed from the ancient SCLM to the juvenile SCLM. Extensional structures in eastern Eurasian continent provide a general architecture of the extensional tectonics of a rifted continent. Progressive extension resulted a sudden collaps of the crust (lithosphere) at ca. 130 to 120 Ma, associated with exhumation of mcc's and giant syn-kinematic magmatism, and post-kinematic magmatism. Parallel extension of both the crust and the mantle resulted in detachment faulting and magmatism, and also contributed to inhomogeneous thinning of the NCC lithosphere. Paleo-Pacific plate subduction and roll-back of the subducting oceanic plate contributed to the PET tectonic processes.

A review on the structural styles of deformation during Late Cretaceous and Paleocene tectonic phases in the southern North Sea area

NASA Astrophysics Data System (ADS)

Deckers, Jef; van der Voet, Eva

2018-04-01

The Mesozoic rifts in the southern North Sea area were affected by Late Cretaceous to Paleocene inversion. Two main inversion phases were traditionally identified in this interval: the Sub-Hercynian and the Laramide phases. The Sub-Hercynian phase started in the early Late Cretaceous, peaked during the Campanian and ended in the late Maastrichtian, while the Laramide phase started in the late Danian and ended in the Thanetian. The Late Cretaceous Sub-Hercynian phase was strong and occurred in several pulses. These pulses led to basin-scale uplift by large reverse movements along basin-bounding faults and resulted in large amounts of erosion (up to 2 km) of Mesozoic and older sediments. The middle Paleocene Laramide phase on the other hand resulted in mild, domal uplift of some Late Cretaceous inverted basins and subsidence (into depocenters) of others. The subsequent Cenozoic inversion phases displayed similar or lower amplitudes and wavelengths of vertical surface movements as the Laramide phase. The transition from the Sub-Hercynian to the Laramide phase in the southern North Sea area therefore coincides with the overall transition from fault-controlled inversion to broad domal vertical surface movements.

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

NASA Astrophysics Data System (ADS)

Cervi, F.; Ronchetti, F.; Martinelli, G.; Bogaard, T. A.; Corsini, A.

2012-11-01

Changes in soil water content, groundwater flow and a rise in pore water pressure are well-known causal or triggering factors for hillslope instability. Rainfall and snowmelt are generally assumed as the main sources of groundwater recharge. This assumption neglects the role of deep water inflow in highly tectonized areas, a factor that can influence long-term pore-pressure regimes and play a role on local slope instability. This paper aims to assess the origin of groundwater in the Ca' Lita landslide (northern Italian Apennines) and to qualify and quantify the aliquot attributable to deep water inflow. The research is essentially based on in situ monitoring and hydrochemical analyses. It involved 5 yr of continuous monitoring of groundwater levels, electrical conductivity and temperature and with groundwater sampling followed by determination of major ions (Na+, K+, Mg2+, Ca2+, Cl-, HCO3-, SO42-), tracers (such as Btot and Sr2+), and isotopes (δ18O, δ2H and 3H). Leaching experiments on soil samples, hydrochemical modelling and water recharge estimation were also carried out. Results show that the groundwater balance in the Ca' Lita landslide must take into account an inflow of deep and highly mineralised Na-SO4 water (more than 9500 μS cm-1) with non-negligible amounts of Cl- (up to 800 mg l-1). The chemical and isotopic fingerprint of this water points to oilfield water hosted at large depths in the Apennine chain and that uprises through a regional fault line crossing the landslide area. It recharges the aquifer hosted in the bedrock underlying the sliding surface (at a rate of about 49 000-85 700 m3 yr-1) and it also partly recharges the landslide body. In both the aquifers, the hydrochemical imprint of deep water mixed with rainfall and snowmelt water was observed. This indicates a probable influence of deep water inflow on the mobility of the Ca' Lita landslide, a finding that could be applicable to other large landslides occurring in highly tectonized areas in the northern Apennines or in other mountain chains. The paper demonstrates that hydrochemistry should, therefore, be considered as a valuable investigation method to define hydrogeological limits and the groundwater sources in hillslope and to assess groundwater flow patterns in deep-seated landslides.

Early Cretaceous ( 140 Ma) aluminous A-type granites in the Tethyan Himalaya, Tibet: Products of crust-mantle interaction during lithospheric extension

NASA Astrophysics Data System (ADS)

Ma, Lin; Kerr, Andrew C.; Wang, Qiang; Jiang, Zi-Qi; Hu, Wan-Long

2018-02-01

A-type granites have been the focus of considerable research due to their distinctive major- and trace-element signatures and tectonic significance. However, their petrogenesis, magmatic source and tectonic setting remain controversial, particularly for aluminous A-type granites. The earliest Cretaceous (ca. 140 Ma) Comei granite in the eastern Tethyan Himalaya is associated with coeval oceanic island basalt (OIB)-type mafic lava, and has A-type granite geochemical characteristics including high 10,000 × Ga/Al (up to 6), FeOtotal/MgO (4.6-6.1) and (Na2O + K2O)/Al2O3 (0.50-0.61) ratios but low CaO (0.6-1.6 wt%) and Na2O (1.8-2.6 wt%) contents. The Comei granite also has variable peraluminous compositions (A/CNK = 1.00-1.36) along with zircon δ18O, εNd(t) and initial 87Sr/86Sr values of 8.2‰ to 9.3‰, - 13.0 to - 12.4 and 0.7238 to 0.7295, respectively. This range of compositions can be interpreted as the interaction between high-temperature upwelling OIB type basaltic magmas and a shallow crustal (< 5 kbar) metapelitic source. The Comei granite and coeval OIB type basaltic rock could represent the earliest stage (145-140 Ma) of a large igneous event in eastern Tethyan Himalaya, which may well have been triggered by pre-breakup lithospheric extension prior to the arrival of the Kerguelen plume head.

Chronology of Miocene-Pliocene deposits at Split Mountain Gorge, Southern California: A record of regional tectonics and Colorado River evolution

USGS Publications Warehouse

Dorsey, R.J.; Fluette, A.; McDougall, K.; Housen, B.A.; Janecke, S.U.; Axen, G.J.; Shirvell, C.R.

2007-01-01

Late Miocene to early Pliocene deposit at Split Mountain Gorge, California, preserve a record of basinal response to changes in regional tectonics, paleogeography, and evolution of the Colorado River. The base of the Elephant Trees Formation, magnetostratigraphically dated as 8.1 ?? 0.4 Ma, provides the earliest well-dated record of extension in the southwestern Salton Trough. The oldest marine sediments are ca. 6.3 Ma. The nearly synchronous timing of marine incursion in the Salton Trough and northern Gulf of California region supports a model for localization of Pacific-North America plate motion in the Gulf ca. 6 Ma. The first appearance of Colorado River sand at the Miocene-Pliocene boundary (5.33 Ma) suggests rapid propagation of the river to the Salton Trough, and supports a lake-spillover hypothesis for initiation of the lower Colorado River. ?? 2007 Geological Society of America.

Some inner satellites of giant planets are still outgassing: Triton, Enceladus, Io

NASA Astrophysics Data System (ADS)

Kochemasov, Gennady G.

2010-05-01

Process of atmospheric formation in the Solar system continues. There are three celestial bodies (except Earth) still emitting considerable amounts of volatiles though these bodies' masses do not allow keeping appreciable amounts of emitted volatiles in their vicinity and creating real atmospheres. It was earlier shown that the wave oscillations in form of stationary waves more or less rapidly changing their phases (plus to minus and inversely) sweep out volatiles from planetary depths [1]. These stationary waves, proportional in their amplitudes to the radii of tectonic granules (Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2) and inversely proportional to orbital frequencies, form the planetary surface relief range of which increases with the solar distance [2]. In the opposite direction increases the sweeping out force of these waves and, consequently, atmospheric masses increase [3]. In the satellite systems of the outer giant planets this regularity is preserved in that the inner satellites (even small as Enceladus) surprisingly continue to push out volatiles. To do so, really very thorough washing out of entire body should be executed by very fine oscillations. Very fast orbits (Triton - 5.9 days; Enceladus - 1.37 d.; Io - 1.769 d.) secure this. Titan with rather fast orbit (16 d.) has enough mass and gravity to create and keep an atmosphere. Triton has a tenuous nitrogen atmosphere with small amounts of methane. A part of its crust (the southern "continental" segment) is dotted with geysers believed to erupt nitrogen with some admixture of dust entrained from beneath the surface. The geyser plumes are up to 8 km high. There are many streaks of dark material laid down by the geyser activity. Enceladus spews out icy material from the south pole region called "Tiger stripes". Some of the tiny ice particles go into Saturn orbit, forming the doughnut-shaped E ring ("detached Enceladus' atmosphere"). Io has at the moment more than 150 active volcanoes making plumes of sulfur and sulfur dioxide hundreds of kilometers high. It is admitted that Io's orbital eccentricity is a main reason for volcanism creating its patchy atmosphere and plasma tore ("detached atmosphere"). It is interesting that the latest MESSENGER data show that spacious volcanic effusions cover Mercury and one region appears to have experienced a high level of volcanic activity. Chains of small deep pits occur in the region along with the larger 30 km across crater. The innermost planet Mercury is deeply degassed and almost dry. Areal volcanic effusions, clear traces of contraction (escarps or lobate ledges), numerous chains of deep pits (craters) controlled by lineaments or weakness zones witness this. Not able to keep an atmosphere in the close vicinity to mighty Sun, Mercury still has traces of Na, K, Ca, Mg, and noble gases in its exosphere (but it seems that sputtering from the surface is a main reason for their appearance). References: [1] Kochemasov G.G. (2006) Venus, Earth, Mars, Titan: intensity of wiping out volatiles from celestial bodies and building atmospheres //36th COSPAR Scientific Assembly, Beijing, China, 16-23 July 2006, Abstr. COSPAR2006-A-00789, CD-ROM; [2] Kochemasov G.G. (2009) A regular row of planetary relief ranges connected with tectonic granulations of celestial bodies // New Concepts in Global Tectonics Newsletter, # 51, 58-61. [3] Kochemasov, G.G. (2006). Outgassing of planets in relation to their orbital frequencies // EUROPLANET-2006 Sci. Conference, Sept.22-26, 2006, Berlin, EPSC Abstracts, Vol. 1, EPSC2006-A-00043, CD-ROM.

Tomographic Imaging of the Seismic Structure Beneath the East Anatolian Plateau, Eastern Turkey

NASA Astrophysics Data System (ADS)

Gökalp, Hüseyin

2012-10-01

The high level of seismic activity in eastern Turkey is thought to be mainly associated with the continuing collision of the Arabian and Eurasian tectonic plates. The determination of a detailed three-dimensional (3D) structure is crucial for a better understanding of this on-going collision or subduction process; therefore, a body wave tomographic inversion technique was performed on the region. The tomographic inversion used high quality arrival times from earthquakes occurring in the region from 1999 to 2001 recorded by a temporary 29 station broadband IRIS-PASSCAL array operated by research groups from the Universities of Boğaziçi (Turkey) and Cornell (USA). The data was inverted and consisted of 3,114 P- and 2,298 S-wave arrival times from 252 local events with magnitudes ( M D) ranging from 2.5 to 4.8. The stability and resolution of the results were qualitatively assessed by two synthetic tests: a spike test and checkerboard resolution test and it was found that the models were well resolved for most parts of the imaged domain. The tomographic inversion results reveal significant lateral heterogeneities in the study area to a depth of ~20 km. The P- and S-wave velocity models are consistent with each other and provide evidence for marked heterogeneities in the upper crustal structure beneath eastern Turkey. One of the most important features in the acquired tomographic images is the high velocity anomalies, which are generally parallel to the main tectonic units in the region, existing at shallow depths. This may relate to the existence of ophiolitic units at shallow depths. The other feature is that low velocities are widely dispersed through the 3D structure beneath the region at deeper crustal depths. This feature can be an indicator of the mantle upwelling or support the hypothesis that the Anatolian Plateau is underlain by a partially molten uppermost mantle.

Including geological information in the inverse problem of palaeothermal reconstruction

NASA Astrophysics Data System (ADS)

Trautner, S.; Nielsen, S. B.

2003-04-01

A reliable reconstruction of sediment thermal history is of central importance to the assessment of hydrocarbon potential and the understanding of basin evolution. However, only rarely do sedimentation history and borehole data in the form of present day temperatures and vitrinite reflectance constrain the past thermal evolution to a useful level of accuracy (Gallagher and Sambridge,1992; Nielsen,1998; Trautner and Nielsen,2003). This is reflected in the inverse solutions to the problem of determining heat flow history from borehole data: The recent heat flow is constrained by data while older values are governed by the chosen a prior heat flow. In this paper we reduce this problem by including geological information in the inverse problem. Through a careful analysis of geological and geophysical data the timing of the tectonic processes, which may influence heat flow, can be inferred. The heat flow history is then parameterised to allow for the temporal variations characteristic of the different tectonic events. The inversion scheme applies a Markov chain Monte Carlo (MCMC) approach (Nielsen and Gallagher, 1999; Ferrero and Gallagher,2002), which efficiently explores the model space and futhermore samples the posterior probability distribution of the model. The technique is demonstrated on wells in the northern North Sea with emphasis on the stretching event in Late Jurassic. The wells are characterised by maximum sediment temperature at the present day, which is the worst case for resolution of the past thermal history because vitrinite reflectance is determined mainly by the maximum temperature. Including geological information significantly improves the thermal resolution. Ferrero, C. and Gallagher,K.,2002. Stochastic thermal history modelling.1. Constraining heat flow histories and their uncertainty. Marine and Petroleum Geology, 19, 633-648. Gallagher,K. and Sambridge, M., 1992. The resolution of past heat flow in sedimentary basins from non-linear inversion of geochemical data: the smoothest model approach, with synthetic examples. Geophysical Journal International, 109, 78-95. Nielsen, S.B, 1998. Inversion and sensitivity analysis in basin modelling. Geoscience 98. Keele University, UK, Abstract Volume, 56. Nielsen, S.B. and Gallagher, K., 1999. Efficient sampling of 3-D basin modelling scenarios. Extended Abstracts Volume, 1999 AAPG International Conference &Exhibition, Birmingham, England, September 12-15, 1999, p. 369 - 372. Trautner S. and Nielsen, S.B., 2003. 2-D inverse thermal modelling in the Norwegian shelf using Fast Approximate Forward (FAF) solutions. In R. Marzi and Duppenbecker, S. (Ed.), Multi-Dimensional Basin Modeling, AAPG, in press.

Transdimensional, hierarchical, Bayesian inversion of ambient seismic noise: Australia

NASA Astrophysics Data System (ADS)

Crowder, E.; Rawlinson, N.; Cornwell, D. G.

2017-12-01

We present models of crustal velocity structure in southeastern Australia using a novel, transdimensional and hierarchical, Bayesian inversion approach. The inversion is applied to long-time ambient noise cross-correlations. The study area of SE Australia is thought to represent the eastern margin of Gondwana. Conflicting tectonic models have been proposed to explain the formation of eastern Gondwana and the enigmatic geological relationships in Bass Strait, which separates Tasmania and the mainland. A geologically complex area of crustal accretion, Bass Strait may contain part of an exotic continental block entrained in colliding crusts. Ambient noise data recorded by an array of 24 seismometers is used to produce a high resolution, 3D shear wave velocity model of Bass Strait. Phase velocity maps in the period range 2-30 s are produced and subsequently inverted for 3D shear wave velocity structure. The transdimensional, hierarchical Bayesian, inversion technique is used. This technique proves far superior to linearised inversion. The inversion model is dynamically parameterised during the process, implicitly controlled by the data, and noise is treated as an inversion unknown. The resulting shear wave velocity model shows three sedimentary basins in Bass Strait constrained by slow shear velocities (2.4-2.9 km/s) at 2-10 km depth. These failed rift basins from the breakup of Australia-Antartica appear to be overlying thinned crust, where typical mantle velocities of 3.8-4.0 km/s occur at depths greater than 20 km. High shear wave velocities ( 3.7-3.8 km/s) in our new model also match well with regions of high magnetic and gravity anomalies. Furthermore, we use both Rayleigh and Love wave phase data to to construct Vsv and Vsh maps. These are used to estimate crustal radial anisotropy in the Bass Strait. We interpret that structures delineated by our velocity models support the presence and extent of the exotic Precambrian micro-continent (the Selwyn Block) that was most likely entrained during crustal accretion.

The tectonic setting and evolution of the 2.7 Ga Kalgoorlie-Kurnalpi Rift, a world-class Archean gold province

NASA Astrophysics Data System (ADS)

Witt, Walter K.; Cassidy, Kevin F.; Lu, Yong-Jun; Hagemann, Steffen G.

2018-01-01

The Yilgarn Craton results from three major mantle input events (at ca 3.0-2.9, 2.8 and 2.7 Ga) that have interacted with > 3.0 Ga continental crust. Zircon geochronology and Sm-Nd isotopic data subdivide the craton into an older Yilgarn proto-craton and the younger, more primitive Eastern Goldfields Superterrane (EGST). Formation of the Kalgoorlie-Kurnalpi Rift (KKR) within the EGST was associated with the 2.7 Ga event, which exploited weakened crust at the eastern margin of the Yilgarn proto-craton where thick sequences of komatiite and basalt were erupted between ca 2710 and 2690 Ma in the Kalgoorlie Terrane. Calc-alkaline volcanism in the Kurnalpi Terrane began at ca 2730 Ma and continued to ca 2690 Ma, overlapping rifting and plume-related volcanism in the Kalgoorlie Terrane. Deposition of siliciclastic sedimentary rocks within basins at ca 2660 resulted from an intra-orogenic extensional event and coincided with the transition from High-Ca to Low-Ca granite magmatism and peak emplacement of intrusions with a metasomatised mantle source component. Most aspects of the KKR are satisfied by broadly coincident plume-related magmatism in the Kalgoorlie Terrane and westward subduction to the east of the Burtville Terrane. Geochemical characteristics of 2730-2700 Ma calc-alkaline volcanism and 2685-2630 Ma low-SiO2 and alkali-rich intrusions support models for a continental margin subduction zone setting. World-class gold deposits formed in reactivated margins of the KKR, which became flux zones for mantle-derived magmas, hydrothermal fluids and heat during 2675-2620 Ma orogenesis. The orogenic gold mineralisation can be subdivided into proximal intrusion-related and distal-source deposits.

Inverse agonist abolishes desensitization of a constitutively active mutant of thyrotropin-releasing hormone receptor: role of cellular calcium and protein kinase C

PubMed Central

Grimberg, Hagit; Zaltsman, Ilona; Lupu-Meiri, Monica; Gershengorn, Marvin C; Oron, Yoram

1999-01-01

C335Stop is a constitutively active mutant of the TRH receptor (TRH-R). To investigate the mechanism of the decreased responsiveness of C335Stop TRH-R, we studied cellular Ca2+ concentrations ([Ca2+]i) in AtT20 cells stably transfected with C335Stop TRH-R cDNA, or Ca2+-activated chloride currents in Xenopus laevis oocytes expressing this mutant receptor after injection of cRNA. The competitive TRH-R binding antagonist, chlorodiazepoxide (CDE), was used as an inverse agonist to study the contribution of constitutive activity to desensitization. Acute treatment with CDE resulted in a rapid (within minutes) decrease in [Ca2+]i and an increase in the response amplitude to TRH with no measurable change in receptor density. Conversely, removal of chronically administered CDE caused a rapid increase in [Ca2+]i and a decrease in TRH response amplitude. CDE abolished heterologous desensitization induced by C335Stop TRH-R on muscarinic m1-receptor (m1-R) co-expressed in Xenopus oocytes. Chelation of extracellular calcium with EGTA caused a rapid decrease in [Ca2+]i and a concomitant increase in the response to TRH in AtT20 cells expressing C335Stop TRH-Rs. Chelerythrine, a specific inhibitor of protein kinase C (PKC), reversed the heterologous desensitization of the response to acetylcholine (ACh). The phosphoserine/phosphothreonine phosphatase inhibitor, okadaic acid, abolished the effect of chelerythrine. Down-regulation of PKC by chronic exposure to phorbol 12-myristate 13-acetate (PMA) or acute inhibition with chelerythrine caused a partial resensitization of the response to TRH. Western analysis indicated that the α subtype of protein kinase C was down-regulated in cells expressing C335Stop TRH-Rs. Following a 5 min exposure to PMA, the residual αPKC translocated to the particular fraction. We propose that cells expressing the constitutively active mutant TRH-R rapidly desensitize their response, utilizing a mechanism mediated by an increase in [Ca2+]i and PKC. PMID:10204996

3D Photonic Crystals Build Up By Self-Organization Of Nanospheres

DTIC Science & Technology

2006-05-23

variance for simple tetragonal Vst , of which general form is defined in Equation (5), could be an important parameter affecting band structure, and it is...plotted along with gap size both as a function of lattice parameter ratio c/a in Figure 2. Apparently, the inverse of variance, i.e. 1/ Vst , shows a...possible. 0.8 1.0 1.2 1.4 1.6 1.8 -2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 gap size (%) 1/ Vst c/a of simple tetragonal g ap s iz e (% ) 0.85 0.86

Himalayas

Atmospheric Science Data Center

2013-04-16

... million years ago as a result of the collision between the Indian and Eurasian plates, driven by tectonic processes. They continue to grow ... 14, 2000) Blocks 65-75 MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission ...

Impact effects and regional tectonic insights: Backstripping the Chesapeake Bay impact structure

USGS Publications Warehouse

Hayden, T.; Kominz, M.; Powars, D.S.; Edwards, L.E.; Miller, K.G.; Browning, J.V.; Kulpecz, A.A.

2008-01-01

The Chesapeake Bay impact structure is a ca. 35.4 Ma crater located on the eastern seaboard of North America. Deposition returned to normal shortly after impact, resulting in a unique record of both impact-related and subsequent passive margin sedimentation. We use backstripping to show that the impact strongly affected sedimentation for 7 m.y. through impact-derived crustal-scale tectonics, dominated by the effects of sediment compaction and the introduction and subsequent removal of a negative thermal anomaly instead of the expected positive thermal anomaly. After this, the area was dominated by passive margin thermal subsidence overprinted by periods of regional-scale vertical tectonic events, on the order of tens of meters. Loading due to prograding sediment bodies may have generated these events. ?? 2008 The Geological Society of America.

Groundwater solute chemistry and arsenic fate in aquifer of Brahmaputra river basin, India: Controls of geology and tectonic setting

NASA Astrophysics Data System (ADS)

Verma, S.; Mukherjee, A.; Mahanta, C.

2015-12-01

Elevated arsenic (As) concentrations in groundwater of the river Brahmaputra basin of India has been largely undocumented, and unexplored. Hydrogeochemical investigations in three different tectono-geomorphic settings of the basin i.e. the northwestern and northern part (located along foothills of the Eastern Himalayas) and southern part (in vicinity of Naga-thrust belt) demonstrate regional variability of groundwater chemistry and redox conditions with geology. Shallow alluvial aquifers of southern part, which are mainly composed of black/dark grey clay and fine sands are affected by high arsenic concentration whereas groundwater from sandy aquifer in the northwestern and northern part have comparatively lower As concentrations. Stable isotopes (δ2H and δ18O) in groundwater indicate suggest that some evaporation may have taken place through recharging water in the study areas. The major-ion composition shows that groundwater of northwestern and northern part are dominated by Ca2+-HCO3-, Ca2+-Na+-HCO3 while southern part is dominated by Na+-Ca2+-HCO3- hydrochemical facies. Molar ratios suggested that most groundwater solutes of northwestern and northern parts were derived from both silicate weathering and carbonate dissolution and have not been affected by cation exchange, while silicate weathering process dominates in aquifers of southern where cation exchange probably has little influence on water chemistry. Thermodynamic calculations show that most of samples fall along the equilibrium line between kaolinite and smectite. While, positive correlations of As with Fe, Mn and HCO3 were observed in northwestern and northern parts aquifers, no consistent correlation of As with any parameter was observed in the aquifers of southern part. Therefore, the results of the study clearly indicate geological control (i.e. change in lithofacies, tectonic set-up) on groundwater chemistry and distribution of redox-sensitive solutes such as As.

Paleostress maps and structural evolution of the Pontides

NASA Astrophysics Data System (ADS)

Hippolyte, Jean-Claude; Espurt, Nicolas; Kaymakci, Nuretdin; Sangu, Ercan; Müller, Carla

2014-05-01

In the frame of DARIUS programme we worked from 2010 to 2012 in the central and eastern Pontides. We aimed at understanding the timing and the characteristics of the extensional and compressional episodes that occurred along the southern margin of the Black Sea (Pontides belt). We used stress inversion technique (Angelier's softwares) for analyzing fault kinematics and characterizing the successive tectonic episodes in terms of paleostresses. The age of the tectonic episodes was constrained by combining structural analysis with nannoplankton dating of the sedimentary units. 1) In the central Pontides, structural analysis shows that deposition of the Barremian-Albian terrigenous sediments of the "syn-rift" Çaglayan Group was controlled by large normal faults under an ESE-WNW extension probably related to the SE-directed opening of the western Black Sea Basin. In contrast, the Coniacian-Santonian and the Paleocene "post-rift" sequences were deposited under NE-SW extension probably related to the SW-directed opening of the eastern Black Sea Basin. At the beginning of Eocene the stress regime changed from extensional to compressional which resulted in the formation of syn-compressional basins. In order to illustrate the two-dimensional structural evolution of the central Pontides we built a NNE-trending 75 km long balanced and restored cross section between Boyabat and Sinop cities. The section is constrained by 183 sites of field data, 5 seismic lines and 8 wells. We model the Pontides as a bi-vergent structure resulting from the structural inversion of Cretaceous normal faults of the southern Black Sea margin. Apatite fission track data along this section suggest that inversion started in the earliest Eocene (~55 Ma). Eocene-Miocene shortening reached ~28 km. 2) In the eastern Pontides, an early Campanian to late Paleocene NW-SE extension was followed by three successive compressional events. A Paleocene to early Eocene NW-SE compression resulted in the formation of the main structural elements of the eastern Pontides. This compression is probably the consequence of the oblique collision of the Tauride block in the South. Paleogene sediments in the Tercan region are interpreted as remnants of a flexural basin related to this collision. A more recent NE-SW compression created interference fold structures in particular in the easternmost Pontides. It may be related to the middle Miocene collision of the Arabian plate. The last event is a N-S to NW-SE compressional to transcurrent tectonics that uplifted the Tercan foreland basin. The change from the Miocene NE-SW compression to the modern stress field is correlated with the change from shortening to escape related strike-slip tectonics that occurred in the Zagros Belt and gave way to the inception of the North Anatolian Fault Zone along the southern margin of the Pontides Belt.

Excitation-dependent local symmetry reversal in single host lattice Ba2A(BO3)2:Eu3+ [A = Mg and Ca] phosphors with tunable emission colours.

PubMed

Jayakiruba, S; Chandrasekaran, S Selva; Murugan, P; Lakshminarasimhan, N

2017-07-05

Eu 3+ activated phosphors are widely used as red emitters in various display devices and light emitting diodes (LEDs). The emission characteristics of Eu 3+ depend on the local site symmetry. The present study demonstrates the role of excitation-dependent local symmetry changes due to the structural reorganization on the emission colour tuning of Eu 3+ from orange-red to orange in single host lattices, Ba 2 Mg(BO 3 ) 2 and Ba 2 Ca(BO 3 ) 2 . The choice of these lattices was based on the difference in the extent of strain experienced by the oxygen atoms. The samples with Eu 3+ at Ba or Mg (Ca) sites were synthesized using the conventional high-temperature solid-state reaction method. The samples were characterized using powder XRD, 11 B MAS-NMR, FT-IR, and diffuse reflectance UV-Vis spectroscopic techniques. The room temperature photoluminescence (PL) recorded using different excitation wavelengths revealed a clear difference in the PL emission features due to symmetry reversal from non-inversion to inversion symmetry around Eu 3+ . The reorganization of highly strained oxygen atoms leads to such symmetry reversal. First-principles calculations were used to deduce the optimized structures of the two borate host lattices, and local geometries and their distortions upon Eu 3+ substitution. The outcomes of these calculations support the experimental findings.

Sequence stratigraphy, tectonics and hydrocarbon trap geometries of Middle Tertiary strata in the southern San Joaquin Basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, S.; Hewlett, J.S.; Bazeley, W.J.M.

1996-01-01

Tectonic evolution of the southern San Joaquin basin exerted a fundamental control on Cenozoic sequence boundary development, reservoir, source and seal facies distribution, and hydrocarbon trap development. Spatial and temporal variations in Tertiary sequence architecture across the basin reflect differences in eastside versus westside basin-margin geometries and deformation histories. Deposition of Tertiary sequences initiated in a forearc basin setting, bounded on the east by a ramp-margin adjacent to the eroded Sierran arc complex and on the west by the imbricated accretionary wedge of the Coast Ranges thrust. The major stages of Cenozoic basin evolution are: (1) Episodic compressional folding andmore » thrusting associated with oblique convergence of the Farallon and North American plates (Late Cretaceous to Oligocene), (2) localized folding and onset of basin subsidence related to Pacific Plate reorganization, microplate formation and rotation (Oligocene to Early Miocene), (3) transtensional faulting, folding basin subsidence associated with initiation of the San Andreas transform and continued microplate rotation (Micocene to Pliocene), and (4) compressional folding, extensional and strike- slip faulting related to evolution of the Pacific-North American transform boundary (Plio- Pleistocene). Complex stratigraphic relationships within Eocene to Middle Miocene rocks provide examples of tectonic influences on sequence architecture. These include development of: (1) Tectonically enhanced sequence boundaries (Early Eocene base Domengine unconformity) and local mid-sequence angular unconformities, (2) westside-derived syntectonic [open quotes]lowstand[close quotes] systems (Yokut/Turitella Silt wedge and Leda Sand/Cymric/Salt Creek wedge), (3) regional seals associated with subsidence-related transgressions (Round Mountain Silt), and (4) combination traps formed by structural inversion of distal lowstand delta reservoirs (e.g. Coalinga East Extension field).« less

Sequence stratigraphy, tectonics and hydrocarbon trap geometries of Middle Tertiary strata in the southern San Joaquin Basin, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, S.; Hewlett, J.S.; Bazeley, W.J.M.

1996-12-31

Tectonic evolution of the southern San Joaquin basin exerted a fundamental control on Cenozoic sequence boundary development, reservoir, source and seal facies distribution, and hydrocarbon trap development. Spatial and temporal variations in Tertiary sequence architecture across the basin reflect differences in eastside versus westside basin-margin geometries and deformation histories. Deposition of Tertiary sequences initiated in a forearc basin setting, bounded on the east by a ramp-margin adjacent to the eroded Sierran arc complex and on the west by the imbricated accretionary wedge of the Coast Ranges thrust. The major stages of Cenozoic basin evolution are: (1) Episodic compressional folding andmore » thrusting associated with oblique convergence of the Farallon and North American plates (Late Cretaceous to Oligocene), (2) localized folding and onset of basin subsidence related to Pacific Plate reorganization, microplate formation and rotation (Oligocene to Early Miocene), (3) transtensional faulting, folding basin subsidence associated with initiation of the San Andreas transform and continued microplate rotation (Micocene to Pliocene), and (4) compressional folding, extensional and strike- slip faulting related to evolution of the Pacific-North American transform boundary (Plio- Pleistocene). Complex stratigraphic relationships within Eocene to Middle Miocene rocks provide examples of tectonic influences on sequence architecture. These include development of: (1) Tectonically enhanced sequence boundaries (Early Eocene base Domengine unconformity) and local mid-sequence angular unconformities, (2) westside-derived syntectonic {open_quotes}lowstand{close_quotes} systems (Yokut/Turitella Silt wedge and Leda Sand/Cymric/Salt Creek wedge), (3) regional seals associated with subsidence-related transgressions (Round Mountain Silt), and (4) combination traps formed by structural inversion of distal lowstand delta reservoirs (e.g. Coalinga East Extension field).« less

1.45 Ga granulites in the southwestern Grenville province: Geologic setting, P-T conditions, and U-Pb geochronology

NASA Astrophysics Data System (ADS)

Ketchum, J. W. F.; Jamieson, R. A.; Heaman, L. M.; Culshaw, N. G.; Krogh, T. E.

1994-03-01

In the southwestern Grenville province, the parautochthonous Britt domain includes a variety of pre-Grenvillian metamorphic and plutonic rocks that were reworked at upper amphibolite facies during the Grenvillian orogeny. Near Pointe-au-Baril, Ontario, a crustal block containing pre-Grenvillian granulite facies mineral assemblages and pre-Grenvillian to early Grenvillian tectonic fabrics has been identified. The block is bounded on the northwest and southeast by extensional shear zones that may have isolated it from regional late Gren- villian deformation. Multiequilibria pressure-temperature (P-T) calculations for orthopyroxene-bearing mafic rocks suggest conditions of 625-700 °C and 7.2-8.4 kbar for the pre-Grenvillian metamorphism. The granulite facies assemblages were locally overprinted during higher pressure Grenvillian metamorphism, which peaked at 720-775 °C and 10.8-11.5 kbar. U-Pb zircon data from migmatitic, mafic supracrustal gneiss indicate metamorphism and leucosome development at ca. 1450-1430 Ma, in agreement with other pre-Grenvillian metamorphic ages for the Central gneiss belt and Grenville Front tectonic zone. An expanding data base on pre-Grenvillian events in the southwestern Grenville province indicates that high-grade metamorphism at ca. 1450-1430 Ma affected a large region of crust and was coeval with widespread felsic to intermediate plutonism.

Knickpoint retreat and landscape evolution of the Amatlán de Cañas half-graben (northern sector of Jalisco Block, western Mexico)

NASA Astrophysics Data System (ADS)

Castillo, Miguel; Ferrari, Luca; Muñoz-Salinas, Esperanza

2017-08-01

Rivers are known to respond to changes in the rate of rock uplift by propagating knickpoints through the fluvial network. Downstream of knickpoints, river incision increases local relief producing also the steepening of hillslopes. Thus, knickpoints convey information about the amount of rock uplift to which the fluvial system must respond. Because the incisional pulse produced by the rapid rock uplift is recorded in the topography of channels, the analysis of longitudinal profiles can be used for evaluating the response of landscape to tectonic activity. Here we analyse the longitudinal profile of rivers (n = 84) and the river basin topography (n = 72) with the aim of unravelling the evolution of the Amatlán de Cañas half-graben (ACHG), a Plio-Quaternary structure located in the northern sector of the Jalisco Block (west-central Mexico). Our results indicate that two rock uplift pulses formed the footwall of the ACHG. The distance of knickpoint retreat from the fault scarp exhibit a strong correlation with the stream length (R2 = 0.80), highlighting the importance of stream discharge on knickpoint migration. Clustering of high values of relief, river incision and normalised channel steepness index (ksn) around the centre of the footwall confirms that this is the zone of maximum throw. The propagation of knickpoints along Ameca river is producing the degradation of fans and relief rejuvenation. Using compiled data of knickpoint retreat rates of other tectonically active landscapes, it was found that the stream discharge and the timing and rate of rock uplift are together a first order control on the rate of knickpoint recession. This study supports the idea that the understanding of knickpoints is crucial to unravel the evolution of tectonically active landscapes.

Modeling temporal changes of low-frequency earthquake bursts near Parkfield, CA

NASA Astrophysics Data System (ADS)

Wu, C.; Daub, E. G.

2016-12-01

Tectonic tremor and low-frequency earthquakes (LFE) are found in the deeper crust of various tectonic environments in the last decade. LFEs are presumed to be caused by failure of deep fault patches during a slow slip event, and the long-term variation in LFE recurrence could provide crucial insight into the deep fault zone processes that may lead to future large earthquakes. However, the physical mechanisms causing the temporal changes of LFE recurrence are still under debate. In this study, we combine observations of long-term changes in LFE burst activities near Parkfield, CA with a brittle and ductile friction (BDF) model, and use the model to constrain the possible physical mechanisms causing the observed long-term changes in LFE burst activities after the 2004 M6 Parkfield earthquake. The BDF model mimics the slipping of deep fault patches by a spring-drugged block slider with both brittle and ductile friction components. We use the BDF model to test possible mechanisms including static stress imposed by the Parkfield earthquake, changes in pore pressure, tectonic force, afterslip, brittle friction strength, and brittle contact failure distance. The simulation results suggest that changes in brittle friction strength and failure distance are more likely to cause the observed changes in LFE bursts than other mechanisms.

Earth tides, global heat flow, and tectonics

USGS Publications Warehouse

Shaw, H.R.

1970-01-01

The power of a heat engine ignited by tidal energy can account for geologically reasonable rates of average magma production and sea floor spreading. These rates control similarity of heat flux over continents and oceans because of an inverse relationship between respective depth intervals for mass transfer and consequent distributions of radiogenic heat production.

Multi-Grid and Resolution Full-Wave Tomography and Moment Tensor Inversion (Postprint)

DTIC Science & Technology

2012-06-04

Denver: University of Colorado. Chen, P., L. Zhao, and T.H. Jordan (2007). Full 3D tomography for crustal structure of the Los Angeles Region, Bull...M.J.R. Wortel, and W. Spakman (2006). Subduction history of the Tethyan region derived from seismic tomography and tectonic reconstructions, J. Geophys

Anisotropy of electrical conductivity of the excavation damaged zone in the Mont Terri Underground Rock Laboratory

NASA Astrophysics Data System (ADS)

Nicollin, Florence; Gibert, Dominique; Lesparre, Nolwenn; Nussbaum, Christophe

2010-04-01

Electrical resistivity measurements were performed to characterize the anisotropy of electrical resistivity of the excavation damaged zone (EDZ) at the end-face of a gallery in the Opalinus clay of the Mont Terri Underground Rock Laboratory (URL). The data were acquired with a combination of square arrays in 18 zones on the gallery's face and in two series of four boreholes perpendicular to the face. Each data set is independently inverted using simulated annealing to recover the resistivity tensor. Both the stability and the non-uniqueness of the inverse problem are discussed with synthetic examples. The inversion of the data shows that the face is split in two domains separated by a tectonic fracture, with different resistivity values but with a common orientation. The direction of the maximum resistivity is found perpendicular to the bedding plane, and the direction of minimum resistivity is contained in the face's plane. These results show that the geo-electrical structure of the EDZ is controlled by a combination of effects due to tectonics, stratigraphy, and recent fracturing produced by the excavation of the gallery.

Application of random seismic inversion method based on tectonic model in thin sand body research

NASA Astrophysics Data System (ADS)

Dianju, W.; Jianghai, L.; Qingkai, F.

2017-12-01

The oil and gas exploitation at Songliao Basin, Northeast China have already progressed to the period with high water production. The previous detailed reservoir description that based on seismic image, sediment core, borehole logging has great limitations in small scale structural interpretation and thin sand body characterization. Thus, precise guidance for petroleum exploration is badly in need of a more advanced method. To do so, we derived the method of random seismic inversion constrained by tectonic model.It can effectively improve the depicting ability of thin sand bodies, combining numerical simulation techniques, which can credibly reducing the blindness of reservoir analysis from the whole to the local and from the macroscopic to the microscopic. At the same time, this can reduce the limitations of the study under the constraints of different geological conditions of the reservoir, accomplish probably the exact estimation for the effective reservoir. Based on the research, this paper has optimized the regional effective reservoir evaluation and the productive location adjustment of applicability, combined with the practical exploration and development in Aonan oil field.

Global Cooling Drive Tectonic Scale Aridification of Asian Interior since Miocene

NASA Astrophysics Data System (ADS)

Jiang, F.; Zhu, X.

2017-12-01

Global cooling and the uplift of Tibetan Plateau are two potential mechanisms for tectonic scale aridification of Asian interior since Miocene. However, their relative importance is still controversial due to lack of continuous paleoclimate record. Here, using a 164 m long sediment core from Site U1438 in the Amami Sankaku Basin (ASB) in the NW Pacific, we show that the tectonic scale aridification of Asian interior is linked to global cooling rather than the uplift of the Tibetan Plateau. We analyzed the characteristics and variations of clastic mineral (e.g. quartz), clay minerals, radiogenic strontium (Sr) and neodymium (Nd) isotopes of the fine pelagic mud intervals from the sediment core. These new evidences indicate a continuous input of Asian dust from Asian interior to ASB since Miocene. We found that Asian dust in the ASB overall increased starting from ca.15.0 Myr (mid-Miocene), and ca. 3.5 Myr (Late Pliocene). The variations of Asian dust transport and accumulation closely responds to known times of enhanced Asian aridification and prevailing westerlies. The overall and gradual increase of Asian dust since mid-Miocene and Late Pliocene are in agreement with the formation and development of the polar ice caps, and are coupled with the gradual decrease of the global temperature recorded by the δ18O ratio of forams, but lag behind the tectonic uplift of the Tibetan Plateau. We argue that global cooling drove the aridification of the Asian interior and resulted in the increase of Asian dust deposition in the ASB.

Evidence for Depth-Dependent Metasomatism in Cratonic Lithosphere

NASA Astrophysics Data System (ADS)

Eeken, T.; Goes, S. D. B.; Pedersen, H.; Arndt, N. T.; Bouilhol, P.

2017-12-01

The long-term stability of the cratonic cores of continents has been attributed to low temperatures and depletion in iron and water. However, a long-standing enigma is that steady-state thermal models based on heat flow measurements and xenoliths systematically overpredict the seismic velocities in Archean lithospheric mantle. We perform a Monte-Carlo inversion for thermal parameters and water content (leading to metasomatism) to fit 1-D geotherms to average Rayleigh-wave dispersion curves for the Archean Kaapvaal, Yilgarn and Slave cratons and the Proterozoic Baltic Shield below Finland. To satisfactorily match the seismic profiles, we need a significant amount of hydrous and/or carbonated minerals starting between the Moho and 70 km depth and extending down to at least 100-150 km depth (if distributed over this depth range, this requires 0.5 and 1 wt% water for amphiboles, or 0.2 wt% water plus sufficient potassium to form phlogopites or 5 wt% CO2 and sufficient Ca to make carbonate, or a combination thereof). Lithospheric temperatures that lead to a good fit of the seismic constraints are commonly lower than those inferred from xenoliths, but consistent with heat flow constraints. The dispersion data also require differences in Moho heatflux between regions and 100-200°C lower sublithospheric mantle temperatures below Yilgarn, Slave and Finland than below Kaapvaal, consistent with regional tectonic settings inferred from global tomography. Thus, significant upward-increasing metasomatism by water and CO2-rich fluids is a plausible mechanism to explain the average seismic structure of cratonic lithosphere. Such metasomatism would also contribute to the positive chemical buoyancy of cratonic roots.

Deformational history of part of the Acatlán Complex: Late Ordovician Early Silurian and Early Permian orogenesis in southern Mexico

NASA Astrophysics Data System (ADS)

Malone, J. R.; Nance, R. D.; Keppie, J. D.; Dostal, J.

2002-10-01

The Paleozoic Acatlán Complex of southern Mexico comprises polydeformed metasedimentary, granitoid, and mafic-ultramafic rocks variously interpreted as recording the closure of the Iapetus, Rheic, and Ouachitan Oceans. The complex is tectonically juxtaposed on its eastern margin against Grenville-age gneisses (Oaxacan Complex) that are unconformably overlain by Lower Paleozoic strata containing fossils of Gondwanan affinity. A thick siliciclastic unit (Chazumba and Cosoltepec Formations) at the base of the complex is considered part of a Lower Paleozoic accretionary prism with a provenance that isotopically resembles the Oaxacan Complex. This unit is tectonically overridden by a locally eclogitic mafic-ultramafic unit interpreted as a westward-obducted ophiolite, the emplacement of which was synchronous with mylonitic granitoid intrusion at ca. 440 Ma. Both units are unconformably overlain by a deformed volcano-sedimentary sequence (Tecomate Formation) attributed to a volcanic arc of presumed Devonian age. Deformed granitoids in contact with this sequence have been dated at ca. 371 (La Noria granite) and 287 Ma (Totoltepec pluton). Three phases of penetrative deformation (D 1-3) affect the Cosoltepec Formation; the last two correlate with two penetrative deformational phases that affect the Tecomate Formation. D 1 is of unknown kinematics but predates deposition of the Tecomate Formation and likely records obduction at ca. 440 Ma (Acatecan orogeny). A folded foliation in the Totoltepec pluton appears to record both deformational phases in the Tecomate Formation, bracketing D 2 and D 3 between 287 Ma and the deposition of the nonconformably overlying Leonardian Matzitzi Formation. D 2 records north-south dextral transpression and south-vergent thrusting and is attributed to the collision of Gondwana and southern Laurentia (Ouachitan orogeny) at ca. 290 Ma, the kinematics being consistent with the northward motion of Mexico that is required by most continental reconstructions for the final assembly of Pangea. D 3, which produced broadly north-south, upright folds, is also attributed to this collision and likely followed D 2 closely in the latest Paleozoic.

Goechemical and Hydrogeochemical Properties of Cappadocia Geothermal Province

NASA Astrophysics Data System (ADS)

Furkan Sener, Mehmet; Sener, Mehmet; Uysal, Tonguc

2016-04-01

In order to determine the geothermal resource potential of Niǧde, Nevşehir and Aksaray provinces in Central Anatolian Volcanic Province (CAVP), geothermal fluids, surface water, and alteration rock samples from the Cappadocia volcanic zone in Turkey were investigated for their geochemical and stable isotopic characteristics in light of published geological and tectonic studies. Accordingly, the Cappadocia Geothermal Province (CGP) has two different geothermal systems located along tectonic zones including five active and two potential geothermal fields, which are located between Tuzgölü Fault Zone and Keçiboyduran-Melendiz Fault and north of Keçiboyduran-Melendiz Fault. Based on water chemistry and isotope compositions, samples from the first area are characterized by Ca-Mg-HCO3 ve Ca-HCO3 type mineral poor waters and Ca-Na-SO4 and Ca-Mg-SO4 type for the cold waters and the hot waters, respectively, whereas hot waters from the second area are Na-Cl-HCO3 and Ca-Na-HCO3 type mineral poor waters. According to δ18O and δ2H isotope studies, the geothermal waters are fed from meteoric waters. Results of silica geothermometer indicate that the reservoir temperature of Dertalan, Melendiz Mount, Keçiboyduran Mount, Hasan Mount (Keçikalesi), Ziga, Acıgöl, and Derinkuyu geothermal waters are 150-173 oC, 88-117 oC, 91-120 oC, 94-122 oC, 131-156 oC, 157-179 oC; 152-174 oC and 102-130 oC, respectively. The REE composition of geothermal fluids, surface water, and mineral precipitates indicate that temperature has a strong effect on REE fractionation of the sampled fluids. Eu- and Ce- anomalies (Eu/Eu*, Ce/Ce*) are visible in several samples, which are related to the inheritance from the host reservoir rocks and redox-controlled fractionation of these elements during water-rock interactions. REE and Yttrium geochemistry results of altered rock samples and water samples, which were taken from same locations exhibited quite similar features in each system. Hence, it was conclude that the same hydrothermal fluid in geothermal system was reached to the surface and interacted with the surface rocks. Our conceptual geothermal model for Cappadocia Geothermal Province based on our geochemical and hydrogeochemical data in combination with geological and geophysical information suggest that the geothermal resources in this region are controlled by primary (active fault) and secondary (buried fault) tectonic belts. Further, our geochemical data indicate the Paleozoic-Mesozoic marble and gneiss being the reservoir rocks. Geogradient and impending heat fluxes to the surface with a possible crustal thinning, which was developed after regional tectonic activities during the Late Pliocene-Quaternary period, constitutes the heat sources. In addition, our study suggest that the Quaternary tuff and ignimbrites of Cappadocia Volcanics represent the seal rock of the geothermal system. In conclusion this study provide evidence for a significant geothermal potential in the Cappadocia region with well-defined seal rocks. However, further studies are needed to resolve the geothermal fluid source problem. Keywords: Cappadocia, geothermal systems, geochemistry, rare earth elements, hydrogeochemistry, hydrothermal alteration.

Source rupture process of the 2016 Kaikoura, New Zealand earthquake estimated from the kinematic waveform inversion of strong-motion data

NASA Astrophysics Data System (ADS)

Zheng, Ao; Wang, Mingfeng; Yu, Xiangwei; Zhang, Wenbo

2018-03-01

On 2016 November 13, an Mw 7.8 earthquake occurred in the northeast of the South Island of New Zealand near Kaikoura. The earthquake caused severe damages and great impacts on local nature and society. Referring to the tectonic environment and defined active faults, the field investigation and geodetic evidence reveal that at least 12 fault sections ruptured in the earthquake, and the focal mechanism is one of the most complicated in historical earthquakes. On account of the complexity of the source rupture, we propose a multisegment fault model based on the distribution of surface ruptures and active tectonics. We derive the source rupture process of the earthquake using the kinematic waveform inversion method with the multisegment fault model from strong-motion data of 21 stations (0.05-0.35 Hz). The inversion result suggests the rupture initiates in the epicentral area near the Humps fault, and then propagates northeastward along several faults, until the offshore Needles fault. The Mw 7.8 event is a mixture of right-lateral strike and reverse slip, and the maximum slip is approximately 19 m. The synthetic waveforms reproduce the characteristics of the observed ones well. In addition, we synthesize the coseismic offsets distribution of the ruptured region from the slips of upper subfaults in the fault model, which is roughly consistent with the surface breaks observed in the field survey.

Carotenoid intake and adipose tissue carotenoid levels in relation to prostate cancer aggressiveness among African-American and European-American men in the North Carolina-Louisiana prostate cancer project (PCaP).

PubMed

Antwi, Samuel O; Steck, Susan E; Su, L Joseph; Hebert, James R; Zhang, Hongmei; Craft, Neal E; Fontham, Elizabeth T H; Smith, Gary J; Bensen, Jeannette T; Mohler, James L; Arab, Lenore

2016-09-01

Associations between carotenoid intake and prostate cancer (CaP) incidence have varied across studies. This may result from combining indolent with aggressive disease in most studies. This study examined whether carotenoid intake and adipose tissue carotenoid levels were inversely associated with CaP aggressiveness. Data on African-American (AA, n = 1,023) and European-American (EA, n = 1,079) men with incident CaP from North Carolina and Louisiana were analyzed. Dietary carotenoid intake was assessed using a detailed-food frequency questionnaire (FFQ), and abdominal adipose tissue samples were analyzed for carotenoid concentrations using high-performance liquid chromatography. Multivariable logistic regression was used in race-stratified analyses to calculate odds ratios (ORs) and 95% confidence intervals (95%CI) comparing high aggressive CaP with low/intermediate aggressive CaP. Carotenoid intake differed significantly between AAs and EAs, which included higher intake of lycopene among EAs and higher β-cryptoxanthin intake among AAs. Comparing the highest and lowest tertiles, dietary lycopene was associated inversely with high aggressive CaP among EAs (OR = 0.55, 95%CI: 0.34-0.89, Ptrend  = 0.02), while an inverse association was observed between dietary β-cryptoxanthin intake and high aggressive CaP among AAs (OR = 0.56, 95%CI: 0.36-0.87, Ptrend  = 0.01). Adipose tissue α-carotene and lycopene (cis + trans) concentrations were higher among EAs than AAs, and marginally significant inverse linear trends were observed for adipose α-carotene (Ptrend  = 0.07) and lycopene (Ptrend  = 0.11), and CaP aggressiveness among EAs only. These results suggest that diets high in lycopene and β-cryptoxanthin may protect against aggressive CaP among EAs and AAs, respectively. Differences in dietary behaviors may explain the observed racial differences in associations. Prostate 76:1053-1066, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Extent and architecture of major fault systems between northern Victoria Land and the eastern margin of the Wilkes Subglacial Basin (East Antarctica)

NASA Astrophysics Data System (ADS)

Armadillo, E.; Ferraccioli, F.; Balbi, P.; Bozzo, E.

2013-12-01

Terrane bounding and intra-terrane faults of the Ross Orogen in East Antarctica are linked to several phases of Cambrian to Ordovician age subduction and accretion along the active paleo-Pacific margin of Gondwana. Here we compile and analyse new enhanced aeromagnetic anomaly images over the Northern Victoria Land (NVL) segment of the Ross Orogen and the eastern margin of the Wilkes Subglacial Basin (WSB) that help constrain the extent and structural architecture of these fault systems and enable us re-assess their tectonic evolution. Long-wavelength magnetic lows and residual Bouguer gravity highs are modelled as several-km thick inverted sedimentary basins of early Cambrian(?) age. Tectonic inversion occurred along major thrust faults during the late stages of the Ross Orogen, forming a major high-grade pop-up structure within the central Wilson Terrane, flanked by lower grade rocks. The Prince Albert Fault System can now be recongnised as being located to the west of the Exiles Thrust fault system rather than representing its southern continuation. Relatively thin sheets of mylonitic sheared granitoids and possible ultramafic lenses are associated with the late-Ross (ca 480 Ma) Exiles Thrust fault system, while significantly larger and thicker batholiths were emplaced along the Prince Albert Fault System. Recent zircon U-Pb dating over small exposures of gabbro-diorites within the Prince Albert Mountains to the south lead us to propose that this part of the magmatic arc was emplaced during an earlier phase of subduction (~520 Ma or older?), compared to the late-Ross intrusions to the east. Whether the Prince Albert Fault System was indeed a major cryptic suture in early Cambrian times (Ferraccioli et al., 2002, GRL) remains speculative, but possible. Our aeromagnetic interpretation leads us to conclude that these inherited terrane bounding and intra-terrane fault systems of the Ross Orogen exerted a key influence on Cenozoic tectonic blocks and faults of the Transantarctic Mountains, and that the eastern margin of the WSB adjacent to NVL was also strongly controlled by a complex array of major intraplate strike-slip fault systems.

Tectonic analysis and paleo-stress determination of the upper lava section at ODP/IODP site 1256 (East Pacific Ocean)

NASA Astrophysics Data System (ADS)

Fontana, Emanuele

2015-09-01

Research on the deep sea is of great importance for a better understanding of the mechanism of magma emplacement and the tectonic evolution of oceanic crust. However, details of the internal structure in the upper levels of the oceanic crust are much less complete than that of the more fully studied sub-aerial areas. For the first time, this study proposes a dynamic analysis using the inversion method on core data derived from the drilled basement of the present-day intact oceanic crust at ODP/IODP Site 1256 in the Cocos plate. The research is based on an innovative core reorientation process and combines different stress hypothesis approaches for the analysis of heterogeneous failure-slip data via exploitation of two distinct techniques. From the analysis of the failure-slip data, both techniques produce 5 distinct subsystem datasets. All calculated subsystems are mechanically and geometrically admissible. Interpretation of the results allows the researchers to note a complex local and regional tectonic evolution deriving from the interplay of (1) the ridge push and rotation of both the East Pacific Rise and the Cocos-Nazca Spreading Center, (2) the effect of the slab pull of the Middle America Trench, (3) the influence of lava emplacement mechanisms, and (4) intra-plate deformation.

Block modeling of crustal deformation in Tierra del Fuego from GNSS velocities

NASA Astrophysics Data System (ADS)

Mendoza, L.; Richter, A.; Fritsche, M.; Hormaechea, J. L.; Perdomo, R.; Dietrich, R.

2015-05-01

The Tierra del Fuego (TDF) main island is divided by a major transform boundary between the South America and Scotia tectonic plates. Using a block model, we infer slip rates, locking depths and inclinations of active faults in TDF from inversion of site velocities derived from Global Navigation Satellite System observations. We use interseismic velocities from 48 sites, obtained from field measurements spanning 20 years. Euler vectors consistent with a simple seismic cycle are estimated for each block. In addition, we introduce far-field information into the modeling by applying constraints on Euler vectors of major tectonic plates. The difference between model and observed surface deformation near the Magallanes Fagnano Fault System (MFS) is reduced by considering finite dip in the forward model. For this tectonic boundary global plate circuits models predict relative movements between 7 and 9 mm yr- 1, while our regional model indicates that a strike-slip rate of 5.9 ± 0.2 mm yr- 1 is accommodated across the MFS. Our results indicate faults dipping 66- 4+ 6° southward, locked to a depth of 11- 5+ 5 km, which are consistent with geological models for the MFS. However, normal slip also dominates the fault perpendicular motion throughout the eastern MFS, with a maximum rate along the Fagnano Lake.

Synaptotagmin 4 Regulates Pancreatic β Cell Maturation by Modulating the Ca2+ Sensitivity of Insulin Secretion Vesicles.

PubMed

Huang, Chen; Walker, Emily M; Dadi, Prasanna K; Hu, Ruiying; Xu, Yanwen; Zhang, Wenjian; Sanavia, Tiziana; Mun, Jisoo; Liu, Jennifer; Nair, Gopika G; Tan, Hwee Yim Angeline; Wang, Sui; Magnuson, Mark A; Stoeckert, Christian J; Hebrok, Matthias; Gannon, Maureen; Han, Weiping; Stein, Roland; Jacobson, David A; Gu, Guoqiang

2018-05-07

Islet β cells from newborn mammals exhibit high basal insulin secretion and poor glucose-stimulated insulin secretion (GSIS). Here we show that β cells of newborns secrete more insulin than adults in response to similar intracellular Ca 2+ concentrations, suggesting differences in the Ca 2+ sensitivity of insulin secretion. Synaptotagmin 4 (Syt4), a non-Ca 2+ binding paralog of the β cell Ca 2+ sensor Syt7, increased by ∼8-fold during β cell maturation. Syt4 ablation increased basal insulin secretion and compromised GSIS. Precocious Syt4 expression repressed basal insulin secretion but also impaired islet morphogenesis and GSIS. Syt4 was localized on insulin granules and Syt4 levels inversely related to the number of readily releasable vesicles. Thus, transcriptional regulation of Syt4 affects insulin secretion; Syt4 expression is regulated in part by Myt transcription factors, which repress Syt4 transcription. Finally, human SYT4 regulated GSIS in EndoC-βH1 cells, a human β cell line. These findings reveal the role that altered Ca 2+ sensing plays in regulating β cell maturation. Copyright © 2018 Elsevier Inc. All rights reserved.

Population inversion calculations using near resonant charge exchange as a pumping mechanism

NASA Technical Reports Server (NTRS)

Chubb, D. L.; Rose, J. R.

1972-01-01

Near resonance charge exchange between ions of a large ionization potential gas such as helium or neon and vapors of metals such as zinc, cadmium, selenium, or tellurium has produced laser action in the metal ion gas. The possibility of obtaining population inversions in near resonant charge exchange systems (Xe-Ca, Xe-Mg, Xe-Sr, Xe-Ba, Ar-Mg, N-Ca) was investigated. The analysis is an initial value problem that utilizes rate equations for the densities of relevant levels of the laser gas (Ca, Ba, Mg, or Sr) and an electron energy equation. Electron excitation rates are calculated using the Bohr-Thomson approximation for the cross section. Approximations to experimental values of the electron ionization cross section and the ion-atom charge exchange cross section are used. Preliminary results have been obtained for the Ca-Xe system and show that it is possible to obtain gains greater than 10 to the 14th power/m with inversion times up to 8x10 to the minus 7th power second. A possible charge exchange laser system using a MPD arc plasma accelerator is also described.

Estimating tectonic history through basin simulation-enhanced seismic inversion: Geoinformatics for sedimentary basins

USGS Publications Warehouse

Tandon, K.; Tuncay, K.; Hubbard, K.; Comer, J.; Ortoleva, P.

2004-01-01

A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic optimization technique are found to be most effective in determining the optimal value of the tectonic parameters. Preliminary 1-D studies indicate that one can determine the geothermal gradient even in the presence of observation and numerical uncertainties. The algorithm succeeds even when the synthetic data has detailed information only in a limited depth interval and has a different dominant frequency in the synthetic and observed seismograms. The methodology presented here even works when the basin input data contains only 75 per cent of the stratigraphic layering information compared with the actual basin in a limited depth interval.

Integrated geophysical study of the northeastern margin of Tibetan Plateau

NASA Astrophysics Data System (ADS)

Shi, L.; Meng, X.; Guo, L.

2011-12-01

Tibetan Plateau, the so-called "Roof of the World", is a direct consequence of collision of the Indian plate with the Eurasian plate starting in the early Cenozoic time. The continent-continent collision is still going on. The northeastern margin of Tibetan Plateau is the front part of the Tibetan Plateau extends to mainland and favorable area for studying uplift and deformation of the Tibetan Plateau. In the past decades, a variety of geophysical methods were conducted to study geodynamics and geological tectonics of this region. We assembled satellite-derived free-air gravity anomalies with a resolution of one arc-minute from the Scripps Institution of Oceanography, and reduced them to obtain Complete Bouguer Gravity Anomalies. Then we gridded Complete Bouguer Gravity Anomalies on a regular grid, and subsequently processed them with the preferential continuation method to attenuate high-frequency noise and analyzed regional and residual anomalies. We also calculated tilt-angle derivative of Complete Bouguer Gravity Anomalies to derive clearer geological structures with more details. Then we calculated the depth distribution of the Moho discontinuity surface in this area by 3D density interface inversion. From the results of preliminary processing, we analyzed the main deep faults and geological tectonics in this region. We extracted seven important profiles' data of Complete Bouguer Gravity Anomalies in this area, and then did forward modeling and inversion on each profile with constraints of geological information and other geophysical data. In the future, we will perform 3D constrained inversion of Complete Bouguer Gravity Anomalies in this region for better understanding deep structure and tectonics of the northeastern margin of Tibetan Plateau. Acknowledgment: We acknowledge the financial support of the SinoProbe project (201011039), the Fundamental Research Funds for the Central Universities (2010ZY26 2011PY0184), and the National Natural Science Foundation of China (40904033).

Tectonic stress evolution in the Pan-African Lufilian Arc and its foreland (Katanga, DRC): orogenic bending, late orogenic extensional collapse and transition to rifting

NASA Astrophysics Data System (ADS)

Kipata, M. L.; Delvaux, D.; Sebagenzi, M. N.; Cailteux, J.; Sintubin, M.

2012-04-01

Between the paroxysm of the Lufilian orogeny at ~ 550 Ma and the late Neogene to Quaternary development of the south-western branch of the East African rift system, the tectonic evolution of the Lufilian Arc and Kundelungu foreland in the Katanga region of the Democratic Republic of Congo remains poorly unknown although it caused important Cu-dominated mineral remobilizations leading to world-class ore deposits. This long period is essentially characterized by brittle tectonic deformations that have been investigated by field studies in open mines spread over the entire arc and foreland. Paleostress tensors were computed for a database of 1450 fault-slip data by interactive stress tensor inversion and data subset separation, and the relative succession of 8 brittle deformation events established. The oldest brittle structures observed are related to the Lufilian brittle compressional climax (stage 1). They have been re-oriented during the orogenic bending that led to the arcuate shape of the belt. Unfolding the stress directions from the first stage allows to reconstruct a consistent NE-SW direction of compression for this stage. Constrictional deformation occurred in the central part of the arc, probably during orogenic bending (Stage 2). After the orogenic bending, a sequence of 3 deformation stages marks the progressive onset of late-orogenic extension: strike-slip deformations (stages 3-4) and late-orogenic arc-parallel extension (stage 5). It is proposed that these 3 stages correspond to orogenic collapse. In early Mesozoic, NW-SE compression was induced by a transpressional inversion, interpreted as induced by far-field stresses generated at the southern active margin of Gondwana (stage 6). Since then, this region was affected by rift-related extension, successively in a NE-SW direction (stage 7, Tanganyika trend) and NW-SE direction (stage 8, Moero trend).

Designing Ionic Liquids for CO2 Capture: What’s the role for computation?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brennecke, Joan F.

Presentation on the computational aspects of ionic liquid selection for carbon dioxide capture to the conference attendees at the New Vistas in Molecular Thermodynamics: Experimentation, Molecular Modeling, and Inverse Design, Berkeley, CA, January 7 through 9, 2018

Kinetics of Ca2+ binding to parvalbumin in bovine chromaffin cells: implications for [Ca2+] transients of neuronal dendrites

PubMed Central

Lee, Suk-Ho; Schwaller, Beat; Neher, Erwin

2000-01-01

The effect of parvalbumin (PV) on [Ca2+] transients was investigated by perfusing adrenal chromaffin cells with fura-2 and fluorescein isothiocyanate (FITC)-labelled PV. As PV diffused into cells, the decay of [Ca2+] transients was transformed from monophasic into biphasic. The proportion of the initial fast decay phase increased in parallel with the fluorescence intensity of FITC, indicating that PV is responsible for the initial fast decay phase.The relationship between the fast decay phase and the [Ca2+] level was investigated using depolarizing trains of stimuli. Within a train the relative amplitude of the fast decay phase was inversely dependent on the [Ca2+] level preceding a given stimulus.Based on these observations, we estimated the Ca2+ binding ratio of PV (κP), the apparent dissociation constant of PV for Ca2+ (Kdc,app), and the unbinding rate constant of Ca2+ from PV (kc-) in the cytosol of chromaffin cells. Assuming free [Mg2+] to be 0.14 mm, we obtained values of 51.4 ± 2.0 nm (n = 3) and 0.95 ± 0.026 s−1 (n = 3), for Kdc,app and kc-, respectively.With the parameters obtained in the perfusion study, we simulated [Ca2+] transients, using two different Ca2+ extrusion rates (γ) – 20 and 300 s−1– which represent typical values for chromaffin cells and neuronal dendrites, respectively. The simulation indicated that Ca2+ is pumped out before it is equilibrated with PV, when γ is comparable to the equilibration rates between PV and Ca2+, resulting in the fast decay phase of a biexponential [Ca2+] transient.From these results we conclude that Ca2+ buffers with slow kinetics, such as PV, may cause biexponential decays in [Ca2+] transients, thereby complicating the analysis of endogenous Ca2+ binding ratios (κS) based on time constants. Nevertheless, estimates of κS based on Ca2+ increments provide reasonable estimates for Ca2+ binding ratios before equilibration with PV. PMID:10835044

Prognostic value of preoperative serum CA 242 in Esophageal squamous cell carcinoma cases.

PubMed

Feng, Ji-Feng; Huang, Ying; Chen, Qi-Xun

2013-01-01

Carbohydrate antigen (CA) 242 is inversely related to prognosis in many cancers. However, few data regarding CA 242 in esophageal cancer (EC) are available. The aim of this study was to determine the prognostic value of CA 242 and propose an optimum cut-off point in predicting survival difference in patients with esophageal squamous cell carcinoma (ESCC). A retrospective analysis was conducted of 192 cases. A receiver operating characteristic (ROC) curve for survival prediction was plotted to verify the optimum cuf- off point. Univariate and multivariate analyses were performed to evaluate prognostic parameters for survival. The positive rate for CA 242 was 7.3% (14/192). The ROC curve for survival prediction gave an optimum cut-off of 2.15 (U/ml). Patients with CA 242 ≤ 2.15 U/ml had significantly better 5-year survival than patients with CA 242 >2.15 U/ml (45.4% versus 22.6%; P=0.003). Multivariate analysis showed that differentiation (P=0.033), CA 242 (P=0.017), T grade (P=0.004) and N staging (P<0.001) were independent prognostic factors. Preoperative CA 242 is a predictive factor for long-term survival in ESCC, especially in nodal-negative patients. We conclude that 2.15 U/ml may be the optimum cuf-off point for CA 242 in predicting survival in ESCC.

Age and height distribution of holocene transgressive deposits in eastern North Island, New Zealand

USGS Publications Warehouse

Ota, Y.; Berryman, K.R.; Hull, A.G.; Miyauchi, T.; Iso, N.

1988-01-01

Holocene transgressive deposits are frequently exposed near the present-day coastline of the study area along eastern North Island, New Zealand. They occur in sites of former estuaries that were filled during the postglacial rise in sea level. We present one hundred radiocarbon dates of Holocene transgressive deposits from the study area, ranging in age from ca. 10,000 to 5500 yr B.P. Relative sea level curves up to ca. 6000 yr B.P. were reconstructed for six locations. The curves have similar slopes prior to about 7000 yr B.P., indicating that sea level rise was much more rapid than any tectonic uplift at that time. The postglacial rise in sea level in New Zealand is considered, in general, to have culminated at about 6500 yr B.P. but the upper limit ages of transgressive deposits in our study area vary from ca. 5500 to 7000 yr B.P. At sites where the uplift rate is high the postglacial transgression culminated rather earlier than ca. 6500 yr B.P., and at sites where there is subsidence or there is very low uplift the culmination is later than ca. 6500 yr B.P. Nine of fourteen dates from fossil trees in growth position, that grew in and were buried by estuarine silt, cluster in the age range ca. 8000-8400 yr B.P. These data support the view that there was a minor regression or stillstand in the eustatic sea level rise at that time. Eleven tectonic subregions are recognized in the study area on the basis of average uplift rate. Most of these subregions coincide with those established from the number and ages of younger Holocene marine terraces of probable coseismic origin. ?? 1988.

Crustal stress across the northern Arabian plate and the relationship with the plate boundary forces

NASA Astrophysics Data System (ADS)

Yassminh, Rayan

The region encompassing the collision of northern Arabia with Eurasia is a tectonically heterogeneous region of distributed deformation. The northern Arabia plate is bounded to the west by the subducting Sinai plate and the left-lateral Dead Sea transform. This complexity suggests that there are multiple competing processes that may influence regional tectonics in northern Arabia and adjacent areas. Earthquake mechanisms provide insight into crustal kinematics and stress; however, reliable determination of earthquake source parameters can be challenging in a complex geological region, such as the continental collision zone between the Arabian and Eurasian plates. The goal of this study is to investigate spatial patterns of the crustal stress in the northern Arabian plate and surrounding area. The focal mechanisms used in this study are based on (1) first-motion polarities for earthquakes recorded by Syrian earthquake center during 2000-2011, and (2) regional moment tensors from broadband seismic data, from Turkey and Iraq. First motion focal mechanisms were assigned quality classifications based on the variation of both nodal planes. Regional moment tensor analysis can be significantly influenced by seismic velocity structure; thus, we have divided the study area into regions based on tectonic units. For each region, the velocity model is described using a waveform-modeling technique prior to the regional moment tensor inversion. The resulting focal mechanisms, combined with other previously published focal mechanisms for the study area, provide a basis for stress inversion analysis. The resulting deviatoric stress tensors show the spatial distribution of the maximum horizontal stress varies from NW-SE along the Dead Sea Fault to the N-S toward the east. We interpret this to reflect the eastward change from the transform to collision processes in northern Arabia. Along the Dead Sea Fault, transposition of the sigma-1 and sigma-2 to vertical and horizontal, respectively, may relate to influences from the subducted part of the Sinai plate. This change in regional stress is also consistent with extensional strains observed from GPS velocities.

Simultaneous, Joint Inversion of Seismic Body Wave Travel Times and Satellite Gravity Data for Three-Dimensional Tomographic Imaging of Western Colombia

NASA Astrophysics Data System (ADS)

Dionicio, V.; Rowe, C. A.; Maceira, M.; Zhang, H.; Londoño, J.

2009-12-01

We report on the three-dimensional seismic structure of western Colombia determined through the use of a new, simultaneous, joint inversion tomography algorithm. Using data recorded by the national Seismological Network of Colombia (RSNC), we have selected 3,609 earthquakes recorded at 33 sensors distributed throughout the country, with additional data from stations in neighboring countries. 20,338 P-wave arrivals and 17,041 S-wave arrivals are used to invert for structure within a region extending approximately 72.5 to 77.5 degrees West and 2 to 7.5 degrees North. Our algorithm is a modification of the Maceira and Ammon joint inversion code, in combination with the Zhang and Thurber TomoDD (double-difference tomography) program, with a fast LSQR solver operating on the gridded values jointly. The inversion uses gravity anomalies obtained during the GRACE2 satellite mission, and solves using these values with the seismic travel-times through application of an empirical relationship first proposed by Harkrider, mapping densities to Vp and Vs within earth materials. In previous work, Maceira and Ammon demonstrated that incorporation of gravity data predicts shear wave velocities more accurately than the inversion of surface waves alone, particularly in regions where the crust exhibits abrupt and significant lateral variations in lithology, such as the Tarim Basin. The significant complexity of crustal structure in Colombia, due to its active tectonic environment, makes it a good candidate for the application with gravity and body waves. We present the results of this joint inversion and compare it to results obtained using travel times alone

Integration of remote sensing, geochemical and field data in the Qena-Safaga shear zone: Implications for structural evolution of the Eastern Desert, Egypt

NASA Astrophysics Data System (ADS)

El-Din, Gamal Kamal; Abdelkareem, Mohamed

2018-05-01

The Qena-Safaga shear zone (QSSZ) represents a significant structural characteristic in the Eastern Desert of Egypt. Remote Sensing, field and geochemical data were utilized in the present study. The results revealed that the QSSZ dominated by metamorphic complex (MC) that intruded by syn-tectonic granitoids. The low angle thrust fault brings calc-alkaline metavolcanics to overlie MC and its association. Subsequently, the area is dissected by strike-slip faults and the small elongated basins of Hammamat sediments of Precambrian were accumulated. The MC intruded by late-to post-tectonic granites (LPG) and Dokhan Volcanics which comprise felsic varieties forming distinctive columnar joints. Remote sensing analysis and field data revealed that major sub-vertical conspicuous strike-slip faults (SSF) including sinistral NW-SE and dextral ca. E-W shaped the study area. Various shear zones that accompanying the SSF are running NW-SE, NE-SW, E-W, N-S and ENE-WSW. The obtained shear sense presented a multiphase of deformation on each trend. i.e., the predominant NW-SE strike-slip fault trend started with sinistral displacement and is reactivated during later events to be right (dextral) strike slip cutting with dextral displacement the E-W trending faults; while NE-SW movements are cut by both the N-S and NNW - SSE trends. Remote sensing data revealed that the NW-SE direction that dominated the area is associated with hydrothermal alteration processes. This allowed modifying the major and trace elements of the highly deformed rocks that showed depletion in SiO2 and enrichments in Fe2O3, MnO, Al2O3, TiO2, Na2O, K2O, Cu, Zn and Pb contents. The geochemical signatures of major and trace elements revealed two types of granites including I-type calc-alkaline granites (late-to post-tectonic) that formed during an extensional regime. However, syn-tectonic granitoids are related to subduction-related environment.

Eocene extension in Idaho generated massive sediment floods into Franciscan trench and into Tyee, Great Valley, and Green River basins

USGS Publications Warehouse

Dumitru, Trevor A.; Ernst, W.G.; Wright, James E.; Wooden, Joseph L.; Wells, Ray E.; Farmer, Lucia P.; Kent, Adam J.R.; Graham, Stephan A.

2013-01-01

The Franciscan Complex accretionary prism was assembled during an ∼165-m.y.-long period of subduction of Pacific Ocean plates beneath the western margin of the North American plate. In such fossil subduction complexes, it is generally difficult to reconstruct details of the accretion of continent-derived sediments and to evaluate the factors that controlled accretion. New detrital zircon U-Pb ages indicate that much of the major Coastal belt subunit of the Franciscan Complex represents a massive, relatively brief, surge of near-trench deposition and accretion during Eocene time (ca. 53–49 Ma). Sediments were sourced mainly from the distant Idaho Batholith region rather than the nearby Sierra Nevada. Idaho detritus also fed the Great Valley forearc basin of California (ca. 53–37 Ma), the Tyee forearc basin of coastal Oregon (49 to ca. 36 Ma), and the greater Green River lake basin of Wyoming (50–47 Ma). Plutonism in the Idaho Batholith spanned 98–53 Ma in a contractional setting; it was abruptly superseded by major extension in the Bitterroot, Anaconda, Clearwater, and Priest River metamorphic core complexes (53–40 Ma) and by major volcanism in the Challis volcanic field (51–43 Ma). This extensional tectonism apparently deformed and uplifted a broad region, shedding voluminous sediments toward depocenters to the west and southeast. In the Franciscan Coastal belt, the major increase in sediment input apparently triggered a pulse of massive accretion, a pulse ultimately controlled by continental tectonism far within the interior of the North American plate, rather than by some tectonic event along the plate boundary itself.

Dietary, Supplement, and Adipose Tissue Tocopherols Levels in Relation to Prostate Cancer Aggressiveness Among African and European Americans: The North Carolina-Louisiana Prostate Cancer Project (PCaP)

PubMed Central

Antwi, Samuel; Steck, Susan E.; Su, L. Joseph; Hebert, James R.; Zhang, Hongmei; Fontham, Elizabeth T. H.; Smith, Gary; Bensen, Jeannette T.; Mohler, James L.; Arab, Lenore

2016-01-01

Background Controversies remain over the safety and efficacy of vitamin E (i.e., α–tocopherol) supplementation use for the prevention of prostate cancer (CaP); however, associations of different tocopherol forms and CaP aggressiveness have yet to be examined. Methods This study examined whether food intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherol were associated with CaP aggressiveness among African-American (AA, n=1,023) and European-American (EA, n=1,079) men diagnosed with incident CaP. Dietary tocopherols were estimated from a food frequency questionnaire, supplement use from questionnaire/inventory, and biomarkers from abdominal adipose samples measured using high-performance liquid chromatography. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated from logistic regression comparing high aggressive CaP to low/intermediate aggressive CaP, adjusting for covariates. Results Dietary intakes of α-and δ-tocopherol were related inversely to CaP aggressiveness among EAs [OR (95% CI), highest versus lowest quartile: α-tocopherol, 0.34 (0.17–0.69), Ptrend = 0.006; δ-tocopherol, 0.45 (0.21–0.95) Ptrend = 0.007]. Inverse associations between dietary and supplemental α-tocopherol and CaP aggressiveness were observed among AAs, though these did not reach statistical significance [OR (95% CI), highest versus lowest quartile: dietary α-tocopherol, 0.58 (0.28–1.19), Ptrend = 0.20; supplemental α-tocopherol, 0.64 (0.31–1.21) Ptrend = 0.15]. No significant association was observed between adipose tocopherol levels and CaP aggressiveness [OR (95% CI), highest versus lowest quartiles of α-tocopherol for EAs 1.43 (0.66–3.11) and AAs 0.66 (0.27–1.62)]. Conclusions The inverse associations observed between dietary sources of tocopherols and CaP aggressiveness suggests a beneficial role of food sources of these tocopherols in CaP aggressiveness. PMID:26053590

Experimental study of 38Ar+α reaction cross sections relevant to the 41Ca abundance in the solar system

NASA Astrophysics Data System (ADS)

Talwar, R.; Bojazi, M. J.; Mohr, P.; Auranen, K.; Avila, M. L.; Ayangeakaa, A. D.; Harker, J.; Hoffman, C. R.; Jiang, C. L.; Kuvin, S. A.; Meyer, B. S.; Rehm, K. E.; Santiago-Gonzalez, D.; Sethi, J.; Ugalde, C.; Winkelbauer, J. R.

2018-05-01

In massive stars, the 41Ca(n ,α )38Ar and 41K(p ,α )38Ar reactions have been identified as the key reactions governing the abundance of 41Ca, which is considered as a potential chronometer for solar system formation. So far, due to experimental limitations, the 41Ca(n ,α )38Ar reaction rate is solely based on statistical model calculations. In the present study, we have measured the time-inverse 38Ar(α ,n )41Ca and 38Ar(α ,p )41K reactions using an active target detector. The reactions were studied in inverse kinematics using a 133-MeV 38Ar beam and 4He as the active-gas target. Both excitation functions were measured simultaneously in the energy range of 6.8 ≤Ec .m .≤9.3 MeV. Using detailed balance the 41Ca(n ,α )38Ar and 41K(p ,α )38Ar reaction rates were determined, which suggested a 20% increase in the 41Ca yield from massive stars.

Inverse modeling/transmit power levels : GPS-ABC Workshop VI RTCA, Washington, DC, March 30, 2017.

DOT National Transportation Integrated Search

2017-03-30

This presentation provides models for adjacent band transmitters (base stations and handsets), and : GNSS receiver antenna patterns, as well as provides C/A results for: (1) impacted regions for adjacent band transmitters of : various types, (2) maxi...

What controls diffuse fractures in platform carbonates? Insights from Provence (France) and Apulia (Italy)

NASA Astrophysics Data System (ADS)

Lavenu, Arthur P. C.; Lamarche, Juliette

2018-03-01

Fractures are widespread in rocks and regional opening-mode arrays are commonly ascribed to major tectonic events. However, fractures occur in otherwise undeformed rocks. Some of these are early-developed features independent of tectonics and forming a background network at regional scale. To overcome this lack of understanding, two hydrocarbon reservoir analogues from platform carbonates have been targeted: the Provence (SE France), and the Apulian platform (SE Italy). In both areas, an early fracturing stage has been observed, made of high-angle-to-bedding opening-mode fractures, and bed-parallel stylolites. These features developed synchronously during the first burial stages and prior to major tectonic events. The fracture sets are not genetically related to the present-day layering. Contrarily, fractures developed in a brittle media where facies transitions were not sharp and did not act as mechanical discontinuities. Carbonate facies distribution and early diagenetic imprint constrained the mechanical stratigraphy when fractures occurred. In addition, we observed that fractures related to late tectonic inversion were partly inhibited. Indeed, rock mechanical properties change through time. Characterizing the temporal evolution of carbonate rocks has revealed that diagenesis and sedimentary facies are the prime actors for brittleness and mechanical layering in carbonates.

Strain-induced topological transition in SrRu 2O 6 and CaOs 2O 6

DOE PAGES

Ochi, Masayuki; Arita, Ryotaro; Trivedi, Nandini; ...

2016-05-24

The topological property of SrRumore » $$_2$$O$$_6$$ and isostructural CaOs$$_2$$O$$_6$$ under various strain conditions is investigated using density functional theory. Based on an analysis of parity eigenvalues, we anticipate that a three-dimensional strong topological insulating state should be realized when band inversion is induced at the A point in the hexagonal Brillouin zone. For SrRu$$_2$$O$$_6$$, such a transition requires rather unrealistic tuning, where only the $c$ axis is reduced while other structural parameters are unchanged. However, given the larger spin-orbit coupling and smaller lattice constants in CaOs$$_2$$O$$_6$$, the desired topological transition does occur under uniform compressive strain. Our study paves a way to realize a topological insulating state in a complex oxide, which has not been experimentally demonstrated so far.« less

Holocene relative sea-level change in Hiroshima Bay, Japan: A semi-quantitative reconstruction based on ostracodes

USGS Publications Warehouse

Yasuhara, Moriaki; Seto, Koji

2006-01-01

Holocene relative sea-level changes in Hiroshima Bay were reconstructed from fossil ostracodes from a core, using a semi-quantitative method. In Hiroshima Bay, relative sea level rose rapidly (about 25 m) between ca. 9000 cal yr BP and ca. 5800 cal yr BP, after which it gradually fell (about 5 m) to its present level. The peak in relative sea level occurred at ca. 5800 cal yr BP. The sea-level curve for Hiroshima Bay is similar to curves for tectonically stable areas of Japan (e.g., Osaka Bay). ?? by the Palaeontological Society of Japan.

Mars: Difference Between Lowland and Highland Basalts Confirms A Tendency Observed In Terrestrial and Lunar Basaltic Compositions

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable 1 to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. 2 MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, 3 kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- 4 terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular 5 momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- 6 paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 7 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for 8 these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. 9 MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. Rock density is a very important factor for constructing tectonic blocks in celestial bodies (Theorem 4, [1]). Angular momenta regulation of different level tectonic blocks in rotating bodies is more effec- tively fulfilled at the crustal level as this level has the longest radius. Thus, composition of crustal basalts is very sensitive to hypsometric (tectonic0 position of certain plan- etary blocks. At Earth oceanic hollows are filled with Fe-rich tholeiites (the deepest Pacific depression is filled with the richest in Fe tholeiites), on continents prevail com- paratively Mg-rich continental basalts. Mare basalts of the Moon are predominantly Fe,Ti-rich. At higher crustal levels appear less dense feldspar-rich, KREEP basalts. This tendency for martian basalts became clear after TES experiment on MGS [2]. The TES data on mineralogy of low-albedo regions show that type1 spectra belong to less dense basic rocks (feldspar 50%, pyroxene 25%) than type2 spectra (feldspar 35%, pyroxene + glass 35%). It means that the highland basaltoids are less dense than the lowland ones. It is interesting that the type1 spectral shape is similar to a spec- trum of the Deccan Traps flood basalts [2]. These continental basalts of the low-lying Indostan subcontinent are known to be relatively Fe-rich and approach the oceanic tholeiites. Global gravity, magnetic, basaltic composition data, available upto now for these bodies: Earth, Moon, Mars, indicate that there is a regular planetology capable to make scientific predictions. References: [1] Kochemasov G.G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., v. 1,# 3, 700; [2] Bandfield J.L., Hamilton V.E., Christensen Ph.R. (2000) A global view of martian surface composi- tions from MGS-TES // Science, v.287, # 5458, 1626-1630. MARS: DIFFERENCE BETWEEN LOWLAND AND HIGHLAND BASALTS CONFIRMS A TENDENCY OBSERVED IN TERRESTRIAL AND LUNAR BASALTIC COMPOSITIONS G. Kochemasov, IGEM RAS, 35 Staromonetny, Moscow 109017, Russia, 10 kochem@igem.ru, Fax: (007)(095) 230 21 79 Basalts are very widespread lithology on surfaces of terrestrial planets because their mantles, by general opinion, are predominantly basic in composition. Planetary sur- face unevennesses are often filled with this very fluid under high temperatures ma- terial. Basaltic compositions are however variable and this is helped by a wide iso- morphism of constituent minerals: Na-Ca feldspars and Fe-Mg dark minerals. Ratios between light and dark minerals as well as Fe/Mg ratios in dark minerals play an important role in regulation of basaltic densities. v 11

Petrology, chronology and sequence of vein systems: Systematic magmatic and hydrothermal history of a major intracontinental shear zone, Canadian Appalachians

NASA Astrophysics Data System (ADS)

Pe-Piper, Georgia; Piper, David J. W.; McFarlane, Chris R. M.; Sangster, Chris; Zhang, Yuanyuan; Boucher, Brandon

2018-04-01

Intra-continental shear zones developed during continental collision may experience prolonged magmatism and mineralization. The Cobequid Shear Zone formed part of a NE-SW-trending, orogen-parallel shear system in the late Devonian-early Carboniferous, where syn-tectonic granite-gabbro plutons and volcanic rocks 4 km thick were progressively deformed. In late Carboniferous to Permian, Alleghanian collision of Africa with Laurentia formed the E-W trending Minas Fault Zone, reactivating parts of the Cobequid Shear Zone. The 50 Ma history of hydrothermal mineralization following pluton emplacement is difficult to resolve from field relationships of veins, but SEM study of thin sections provides clear detail on the sequence of mineralization. The general paragenesis is: albite ± quartz ± chlorite ± monazite → biotite → calcite, allanite, pyrite → Fe-carbonates, Fe-oxides, minor sulfides, calcite and synchysite. Chronology was determined from literature reports and new U-Pb LA-ICPMS dating of monazite and allanite in veins. Vein mineralization was closely linked to magmatic events. Vein emplacement occurred preferentially during fault movement recognised from basin-margin inversion, as a result of fractures opening in the damage zone of master faults. The sequence of mineralization, from ca. 355 Ma riebeckite and albite veins to ca. 327 (-305?) Ma siderite-magnetite and sulfide mineralization, resembles Precambrian iron-oxide-copper-gold (IOCG) systems in the literature. The abundant magmatic Na, halogens and CO2 in veins and some magmatic bodies, characteristic of IOCG systems, were derived from the deeply subducted Rheic Ocean slab with little terrigenous sediment. Regional extension of the Magdalen Basin caused asthenospheric upwelling and melting of the previously metasomatized sub-continental lithospheric mantle. Crustal scale strike-slip faulting facilitated the rise of magmas, resulting in high heat flow driving an active hydrothermal system. Table S2 Location of all illustrated samples. Table S3 Monazite geochronology lab data. Table S4 Allanite geochronology lab data. Fig. S1 Monazite geochronology analytical spots. Fig. S2 Allanite geochronology analytical spots.

Temporal and Spatial Evolution of Dynamic Support From River Profiles: A Framework for Madagascar and Africa

NASA Astrophysics Data System (ADS)

Paul, J. D.; Roberts, G. G.; White, N.

2012-04-01

It is generally accepted that the surface topography of Africa is a manifestation of convective circulation in the sub-lithospheric mantle. Here, we present an inverse method whereby longitudinal river profiles are interrogated to extract quantitative estimates of spatial and temporal variations in the rate of tectonic uplift. Surface processes can provide an important window into transient convective circulation in the sub-lithospheric mantle. River profiles act as 'tectonic tape recorders': we assume the generation of broad, convex-upward knickzones to represent the effect of tectonic uplift shifting the river system into a state of disequilibrium. Profiles evolve through time primarily via the headward retreat of these knickzones. We use a conjugate gradient inverse algorithm to minimise the misfit between observed river profiles - derived from a regional Digital Elevation Model (DEM) - and calculated profiles obtained by varying the uplift rate history. We jointly invert a total of 98 Malagasy and 570 African river profiles to obtain a history of the cumulative tectonic uplift through geological time. We show that Africa has undergone two phases of rapid uplift: first in Eocene times; secondly, since 10 Ma. While the first gave rise to broad, long wavelength topography, the second led to more localised domal swells of high relief. We propose the existence of two wavelengths of dynamic support, reflecting a change in the style of convection in the upper mantle since 50 Ma. Our results correlate strongly with independent geological estimates of uplift across Africa and Madagascar, while our calculated landscape surface following 50 Myr of uplift corresponds closely to a surface fit across present-day drainage divides. Finally we calculate the solid sediment flux delivered to major African deltas as a function of time. This onshore record provides an important indirect constraint on the history of vertical motions at the surface, and agrees well with the offshore flux record, obtained from mapping the thickness of chronostratigraphic sediment packages at the deltas.

Magnetotelluric Imaging of Lower Crustal Melt and Lithospheric Hydration in the Rocky Mountain Front Transition Zone, Colorado, USA

NASA Astrophysics Data System (ADS)

Feucht, D. W.; Sheehan, A. F.; Bedrosian, P. A.

2017-12-01

We present an electrical resistivity model of the crust and upper mantle from two-dimensional (2-D) anisotropic inversion of magnetotelluric data collected along a 450 km transect of the Rio Grande rift, southern Rocky Mountains, and High Plains in Colorado, USA. Our model provides a window into the modern-day lithosphere beneath the Rocky Mountain Front to depths in excess of 150 km. Two key features of the 2-D resistivity model are (1) a broad zone ( 200 km wide) of enhanced electrical conductivity (<20 Ωm) in the midcrust to lower crust that is centered beneath the highest elevations of the southern Rocky Mountains and (2) hydrated lithospheric mantle beneath the Great Plains with water content in excess of 100 ppm. We interpret the high conductivity region of the lower crust as a zone of partially molten basalt and associated deep-crustal fluids that is the result of recent (less than 10 Ma) tectonic activity in the region. The recent supply of volatiles and/or heat to the base of the crust in the late Cenozoic implies that modern-day tectonic activity in the western United States extends to at least the western margin of the Great Plains. The transition from conductive to resistive upper mantle is caused by a gradient in lithospheric modification, likely including hydration of nominally anhydrous minerals, with maximum hydration occurring beneath the Rocky Mountain Front. This lithospheric "hydration front" has implications for the tectonic evolution of the continental interior and the mechanisms by which water infiltrates the lithosphere.

Modulation of sarcoplasmic reticulum Ca(2+)-release channels by caffeine, Ca2+, and Mg2+ in skinned myocardial fibers of fetal and adult rats.

PubMed

Su, J Y; Chang, Y I

1993-05-01

Ryanodine causes depression of the caffeine-induced tension transient (ryanodine depression) in skinned muscle fibers, because it blocks the sarcoplasmic reticulum (SR) Ca(2+)-release channels [Su, J. Y. (1988) Pflügers Arch 411:132-136, 371-377; (1992) Pflügers Arch 421:1-6]. This study was performed to examine the sensitivity of SR Ca(2+)-release channels to ryanodine in fetal compared to adult myocardium and to investigate the influence of Ca2+, caffeine, and Mg2+ on ryanodine depression in skinned fibers. Ryanodine (0.3 nM-1 microM) caused a dose-dependent depression in skinned myocardial fibers of the rat, and the fetal fibers (IC50 approximately 74 nM) were 26-fold less sensitive than those of the adult (IC50 approximately 2.9 nM). The depression induced by 0.1 microM or 1 microM ryanodine was a function of [caffeine], or [Ca2+] (pCa < 6.0), which was potentiated by caffeine, and an inverse function of [Mg2+]. At pCa > 8.0 plus 25 mM caffeine, a 20% ryanodine depression was observed in both the fetal and adult fibers, indicating independence from Ca2+. Ryanodine depression in skinned fibers of the fetus was less affected than that seen in the adult by pCai, [caffeine]i, or 25 mM caffeine plus pCai or plus pMgi (IC50 approximately pCa 4.5 versus 5.1; caffeine 12.7 mM versus 2 mM; pCa 6.7 versus 7.3; and pMg 3.9 versus 3.3 respectively). The results show that the SR Ca(2+)-release channel in both fetal and adult myocardium is modulated by Ca2+, caffeine, and Mg2+.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced photoluminescence and thermal stability of divalent ions (Zn2+, Mg2+) assisted CaTiO3:Eu3+ perovskite phosphors for lighting applications

NASA Astrophysics Data System (ADS)

Singh, Dhananjay Kumar; Manam, J.

2018-03-01

Current study proposes the improved red emission of Zn2+ and Mg2+ ions incorporated CaTiO3:Eu3+ phosphors synthesized via the well-known solid-state reaction method. Under the 397 nm UV excitation, the Zn2+- and Mg2+-incorporated CaTiO3:0.15Eu3+ phosphor having orthorhombic structure with space group Pbnm exhibited an intense red emission at 619 nm. This can be credited to the hypersensitive 5D0 → 7F2 transition of Eu3+ ions, which is also indicative of the fact that the Eu3+ ions populated the non-inversion symmetry sites in the CaTiO3 lattices. The optimized composition CaTiO3:0.15Eu3+, 0.20Zn2+ and CaTiO3:0.15Eu3+, 0.10Mg2+ phosphors, pronounces in a magnificent enhancement of PL intensity by 5.5 and 2.5 times, respectively, as compared to CaTiO3:0.15 Eu3+ phosphor. From the temperature-dependent emission spectra, ΔEa were enunciated to be 0.101 and 0.086 eV for CaTiO3:0.15Eu3+, 0.20Zn2+ and CaTiO3:0.15Eu3+, 0.10Mg2+ phosphors, respectively, for thermal quenching. In addition, it can be better understood as related to the adequate thermal stability of 60% even at 450 and 420 K, respectively. Furthermore, the Judd-Ofelt theory was used to study the radiative intensity parameters of Eu3+ ions in the CaTiO3 lattices. The experimental results incited the bright prospects of synthesized ceramics as a promising candidate for lighting applications.

Inverse modeling with RZWQM2 to predict water quality

USGS Publications Warehouse

Nolan, Bernard T.; Malone, Robert W.; Ma, Liwang; Green, Christopher T.; Fienen, Michael N.; Jaynes, Dan B.

2011-01-01

This chapter presents guidelines for autocalibration of the Root Zone Water Quality Model (RZWQM2) by inverse modeling using PEST parameter estimation software (Doherty, 2010). Two sites with diverse climate and management were considered for simulation of N losses by leaching and in drain flow: an almond [Prunus dulcis (Mill.) D.A. Webb] orchard in the San Joaquin Valley, California and the Walnut Creek watershed in central Iowa, which is predominantly in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Inverse modeling provides an objective statistical basis for calibration that involves simultaneous adjustment of model parameters and yields parameter confidence intervals and sensitivities. We describe operation of PEST in both parameter estimation and predictive analysis modes. The goal of parameter estimation is to identify a unique set of parameters that minimize a weighted least squares objective function, and the goal of predictive analysis is to construct a nonlinear confidence interval for a prediction of interest by finding a set of parameters that maximizes or minimizes the prediction while maintaining the model in a calibrated state. We also describe PEST utilities (PAR2PAR, TSPROC) for maintaining ordered relations among model parameters (e.g., soil root growth factor) and for post-processing of RZWQM2 outputs representing different cropping practices at the Iowa site. Inverse modeling provided reasonable fits to observed water and N fluxes and directly benefitted the modeling through: (i) simultaneous adjustment of multiple parameters versus one-at-a-time adjustment in manual approaches; (ii) clear indication by convergence criteria of when calibration is complete; (iii) straightforward detection of nonunique and insensitive parameters, which can affect the stability of PEST and RZWQM2; and (iv) generation of confidence intervals for uncertainty analysis of parameters and model predictions. Composite scaled sensitivities, which reflect the total information provided by the observations for a parameter, indicated that most of the RZWQM2 parameters at the California study site (CA) and Iowa study site (IA) could be reliably estimated by regression. Correlations obtained in the CA case indicated that all model parameters could be uniquely estimated by inverse modeling. Although water content at field capacity was highly correlated with bulk density (−0.94), the correlation is less than the threshold for nonuniqueness (0.95, absolute value basis). Additionally, we used truncated singular value decomposition (SVD) at CA to mitigate potential problems with highly correlated and insensitive parameters. Singular value decomposition estimates linear combinations (eigenvectors) of the original process-model parameters. Parameter confidence intervals (CIs) at CA indicated that parameters were reliably estimated with the possible exception of an organic pool transfer coefficient (R45), which had a comparatively wide CI. However, the 95% confidence interval for R45 (0.03–0.35) is mostly within the range of values reported for this parameter. Predictive analysis at CA generated confidence intervals that were compared with independently measured annual water flux (groundwater recharge) and median nitrate concentration in a collocated monitoring well as part of model evaluation. Both the observed recharge (42.3 cm yr−1) and nitrate concentration (24.3 mg L−1) were within their respective 90% confidence intervals, indicating that overall model error was within acceptable limits.

Field measurements of dry deposition to spruce foliage and petri dishes in the Black Forest, F.R.G.

USGS Publications Warehouse

Shanley, J.B.

1989-01-01

Dry deposition fluxes Ca2+, Mg2+, K+, Mn2+, Pb2+ and SO42- to spruce foliage and petri dishes were measured in two high-elevation sites (>900 m) in the southern Black Forest, F.R.G., during 12 periods (2-7 days, each) from mid-September to mid-November, 1983, In situ extraction of deposited material from small spruce branches allowed repeated use of the same foliar collecting surfaces for a direct comparison of deposition between periods. Fluxes were corrected for leaching of internally cycled constituents using factors determined from serial extraction experiments. The ratio of flux to petri dishes vs foliage (P/F) was >1.0 for Ca2+, Pb2+ and SO42-, and somewhat 900 m) in the southern Black Forest, F.R.G., during 12 periods (2-7 days, each) from mid-September to mid-November, 1983. The ratio of flux to petri dishes vs foliage (P/F) was >1.0 for Ca2+, Pb2+, and SO42-, and somewhat <1.0 but more constant for Mg2+. Temporal variations in dry deposition fluxes at an exposed site near the industrialized Rhine Valley correlated with variations in total air particulate concentrations at a nearby air quality station. Deposition rates were comparable in magnitude but different in temporal pattern at a remote site in the Black Forest interior. Fluxes at each site reached a minimum during the period of 4-9 November when a regional air inversion confined pollutants to the Rhine Valley below the study sites. High fluxes accompanied the inversion break-up.

Thermal and exhumation history of the central Tianshan (NW China): Constraints by U-Pb geochronology and Ar-Ar and (U-Th)/He thermochronology

NASA Astrophysics Data System (ADS)

Yin, J.; Chen, W.; Hodges, K. V.; Xiao, W.; Van Soest, M. C.; Cai, K.; Zhang, B.; Mercer, C. M.; Yuan, C.

2015-12-01

Geochronology and thermochronology using multiple mineral-isotopic chronometers reveals the thermo-tectonic history of the central Tianshan (NW China) from emplacement to exhumation. Granites from the central Tianshan, which are associated with the southward subduction of the northern Tianshan Ocean, have been dated at 362-354 Ma using the LA-ICP-MS Zircon U-Pb method. A younger diorite sample (282 ± 1 Ma, Zircon U-Pb method by LA-ICP-MS) from northern Tianshan formed during the final closure of the Northern Tianshan Ocean when the Junggar Block collided with the Yili-Central Tianshan Block. 40Ar/39Ar step-wise heating plateau dates (biotite Ar/Ar: 312-293 Ma; Plagioclase Ar/Ar: 270-229 Ma) from the Central Tianshan show rapid post-magmatic cooling during the Late Carboniferous-Early Permian followed by a more modest rate of cooling from the middle Permian to the middle Jurassic. The northern Tianshan diorite (biotite Ar/Ar: 240 ± 1 Ma) also reveals a middle Jurassic cooling. Apatite (U-Th )/He dates from the central Tianshan samples range from ca. 130 Ma to ca. 116 Ma. The Apatite (U-Th )/He date for the northern Tianshan sample is ca. 27 Ma. Previous studies also reported Apatite (U-Th)/He ages of ca. 44 Ma-11 Ma in the Baluntai area of the southern Central Tianshan[1]. Two episodes of cooling are distinguished by thermal history modelling: (1) Mesozoic cooling occurred as the result of the exhumation and tectonic reactivation of the central Tianshan; and (2) The Tianshan orogenic belt has been rapidly exhumed since the Middle Cenozoic. References [1] Lü, H.H., Chang, Y., Wang, W., Zhou, Z.Y., 2013. Rapid exhumation of the Tianshan Mountains since the early Miocene: Evidence from combined apatite fission track and (U-Th)/He thermochronology. Science China: Earth Sciences, 43(12): 1964-1974 (in Chinese).

Gravity sliding in basinal setting, a surficial record of tectonic and geodynamic evolution; examples from the southern W. Alps and their foreland

NASA Astrophysics Data System (ADS)

Dumont, T.; Franzi, V.; Matthews, S. J.

2012-04-01

The occurrence of large-scale submarine landslides, although commonly observed in the present basins, is only exceptionally mentioned in the Alpine orogen and foreland. The southern part of the Western Alpine arc and the SE basin of France provide examples of such features which could be related with particular geodynamic events, in relation with the motion of the Iberian and Adriatic microplates : - A >50km2 slump scar formed in Aptian times at the northwestern edge of the SE France (so-called Vocontian) basin, giving a low-angle detachment surface which was onlapped by Albian hemipelagic marls (Ferry & Flandrin, 1979). The latter mark the maximum deepening stage of the basin, and the head of the scar is located over a deep-seated fault bounding the platform, which strongly suggest that sliding was caused by differential subsidence due to Middle Cretaceous extension, as a consequence of Iberia-Europe divergence. - Later on, a deep-marine erosion surface developed further down the basin over a >100km2 area (Dévoluy massif; Michard et al., 2010), which had been previously affected by Mid-Cretaceous extension. Typical inversion structures are found beneath the surface, which indicate that NS shortening overprinted the extensional pattern. The removal of up to 400m of Mesozoic sediments was controlled by gravity processes, probably triggered by the deformation of the basin floor following tectonic inversion. The overlying pelagic carbonates indicate that shortening occurred before the Campanian, which is closely comparable with the earliest stages of tectonic inversion in the Pyrenees. - The transition slope between the Paleogene Alpine flexural basin and the NW-ward propagating accretionary prism provides examples of basin floor degradation and of gravity-driven emplacement of large-scale blocks, generally regarded as thrust-sheets in the Alps. These features allow to reconstruct the early stages of the Adria-Europe collision, which strongly differ from the Oligo-Miocene dynamics and which are overprinted or crosscut by the modern orogen (Dumont et al., 2011). Theses examples show that, in different structural and geodynamic settings, detailed analysis of basin floor morphology, (re)sediments transport directions, syndepositional deformations and provenance of exotic blocks can provide useful information about the regional kinematics, which can be integrated with other datasets, i.e. tectonic, metamorphic, thermochronologic, etc. Dumont T., Schwartz S., Guillot S., Simon-Labric T., Tricart P. & Jourdan S. (2011), Structural and sedimentary records of the Oligocene revolution in the Western Alpine arc. Jour. Geodyn., in press. Ferry S. & Flandrin J. (1979), Mégabrèches de resédimentation, lacunes mécaniques et pseudo-« hard-grounds » sur la marge vocontienne au Barrémien et à l'Aptien inférieur (SE France). Géologie Alpine, 55, p. 75-92. Michard A., Dumont T., Andreani L. & Loget N. (2010), Structural and sedimentary records of the Oligocene revolution in the Western Alpine arc. Bull. Soc. Géol. Fr., 181, p. 565-581.

Carboniferous volcanic rocks associated with back-arc extension in the western Chinese Tianshan, NW China: Insight from temporal-spatial character, petrogenesis and tectonic significance

NASA Astrophysics Data System (ADS)

Su, Wenbo; Cai, Keda; Sun, Min; Wan, Bo; Wang, Xiangsong; Bao, Zihe; Xiao, Wenjiao

2018-06-01

The Yili-Central Tianshan Block, as a Late Paleozoic major continental silver of the Central Asian Orogenic Belt, holds a massive volume of Carboniferous volcanic rocks, occurring as subparallel magmatic belts. However, the petrogenesis and tectonic implications of these volcanic rocks remain enigmatic. This study compiled isotopic age data for mapping their temporal-spatial character, and conducted petrogenetic study of these magmatic belts, aiming to understand their tectonic implications. Our compiled dataset reveals four magmatic belts in the Yili-Central Tianshan Block, including the Keguqinshan-Tulasu belt and the Awulale belt in the north, and the Wusun Mountain belt and the Haerk-Nalati belt in the south. In addition, our new zircon U-Pb dating results define two significant Early Carboniferous eruptive events (ca. 355-350 Ma and 325 Ma) in the Wusun Mountain belt. Volcanic rocks of the early significant eruptive event (ca. 355-350 Ma) in the Wusun Mountain comprise basalt, trachy-andesite, andesite, dacite and rhyolite, which are similar to the typical rock assemblage of a continental arc. Their positive εNd(t) values (+0.3 to +1.5) and relatively high Th/Yb and Nb/Yb ratios suggest the derivation from a mantle source with additions of slab-derived components. The gabbroic dykes and rhyolites of the late volcanic event (ca. 325 Ma) form a bimodal rock association, and they show alkaline features, with relatively low Th/Yb and Th/Nb ratios, and higher positive εNd(t) values (εNd(t) = +3.3-+5.0). It is interpreted that the gabbroic dykes and rhyolites may have been derived from mantle and juvenile crustal sources, respectively. The isotopic and trace elemental variations with time elapse of the Wusun Mountain magmatic belt show an important clue for strengthening depletion of the magma sources. Considering the distinctive temporal-spatial character of the Carboniferous volcanic rocks, two separate subduction systems in the southern and northern margins of the Yili-Central Tianshan Block were suggested to be the causes for extensive emplacements of the igneous products, which may be in an association with synchronous subduction of the South Tianshan and the North Tianshan oceanic plates, respectively. In this tectonic context, the Carboniferous magmatic rocks of the Wusun Mountain may be a tectonic response to the change in magma sources due to back-arc propagation in the western Chinese Tianshan.

Resolution Study of Marine CSEM Imaging of Subduction Zones

NASA Astrophysics Data System (ADS)

Gustafson, C.; Key, K.

2016-12-01

Marine controlled source electromagnetic (CSEM) data allow us to image seafloor electrical resistivity from which we can constrain the porosity and fluid content of the subsurface. In subduction zones, CSEM data can be used to constrain geologic structure, hydrogeology and fluid-tectonic processes. The scales of features we are interested in recovering with CSEM data range from large-scale features such as the incoming tectonic plate and subducting slab, to the narrow dipping plate boundary interface where slip occurs, to thin faults that cut the overriding forearc crust and shallow fluid seeps and mounds on the seafloor. Thus electrical structure is expected to vary on scales ranging from scales of meters to tens of kilometers. CSEM data collected by Scripps at the Middle America Trench in 2010 is the first and to-date the only application of the method for studying a subduction zone. The results from this pioneering data set highlight the types of new discoveries that are possible with CSEM data, such as imaging conductive bending faults and a water-rich channel of subducting sediments. In this work we explore the magnitude and scale of 2D resistivity structures that can be resolved with CSEM data through a suite of synthetic inversion studies. We build resistivity models that are representative of various known and hypothesized subduction zone plate boundary structures. We generate synthetic noisy data for these models and invert them using the freely available MARE2DEM inversion code. We compare the recovered models to the original models in order to determine which resistivity structures may be successfully identified using CSEM. We explore the potential effects of receiver spacing, frequency bandwidth and system noise levels on the ability of CSEM to recover these different subduction zone structures.

Fingerprinting stress: Stylolite and calcite twinning paleopiezometry revealing the complexity of progressive stress patterns during folding—The case of the Monte Nero anticline in the Apennines, Italy

NASA Astrophysics Data System (ADS)

Beaudoin, Nicolas; Koehn, Daniel; Lacombe, Olivier; Lecouty, Alexandre; Billi, Andrea; Aharonov, Einat; Parlangeau, Camille

2016-07-01

In this study we show for the first time how quantitative stress estimates can be derived by combining calcite twinning and stylolite roughness stress fingerprinting techniques in a fold-and-thrust belt. First, we present a new method that gives access to stress inversion using tectonic stylolites without access to the stylolite surface and compare results with calcite twin inversion. Second, we use our new approach to present a high-resolution deformation and stress history that affected Meso-Cenozoic limestone strata in the Monte Nero Anticline during its late Miocene-Pliocene growth in the Umbria-Marche Arcuate Ridge (northern Apennines, Italy). In this area an extensive stylolite-joint/vein network developed during layer-parallel shortening (LPS), as well as during and after folding. Stress fingerprinting illustrates how stress in the sedimentary strata did build up prior to folding during LPS. The stress regime oscillated between strike slip and compressional during LPS before ultimately becoming strike slip again during late stage fold tightening. Our case study shows that high-resolution stress fingerprinting is possible and that this novel method can be used to unravel temporal relationships that relate to local variations of regional orogenic stresses. Beyond regional implications, this study validates our approach as a new powerful toolbox to high-resolution stress fingerprinting in basins and orogens combining joint and vein analysis with sedimentary and tectonic stylolite and calcite twin inversion techniques.

Distribution of flux-pinning energies in YBa2Cu3O(7-delta) and Bi2Sr2CaCu2O(8+delta) from flux noise

NASA Astrophysics Data System (ADS)

Ferrari, M. J.; Johnson, Mark; Wellstood, Frederick C.; Clarke, John; Mitzi, D.

1990-01-01

The spectral density of the magnetic flux noise measured in high-temperature superconductors in low magnetic fields scales approximately as the inverse of the frequency and increases with temperature. The temperature and frequency dependence of the noise are used to determine the pinning energies of individual flux vortices in thermal equilibrium. The distribution of pinning energies below 0.1 eV in YBa(2)Cu(3)O(7-delta) and near 0.2 eV in Bi(2)Sr(2)CaCu(2)O(8+delta). The noise power is proportional to the ambient magnetic field, indicating that the vortex motion is uncorrelated.

Analysis of seismicity in the region off the southeastern Korean Peninsula after the 2011 M9.0 Tohoku-Oki earthquake

NASA Astrophysics Data System (ADS)

Lee, J.; Kim, T. K.; Kim, W.; Hong, T. K.

2017-12-01

The Korean Peninsula is located in a stable intraplate regime with relatively low seismicity. The seismicity in the Korean Peninsula was, however, changed significantly after the 11 March 2011 M9.0 Tohoku-Oki megathrust earthquake. An M5.0 earthquake occurred in 2016 at the region off the southeastern Korean Peninsula. The M5.0 earthquake was the largest event in the region since 1978 when the national seismic monitoring began. Several nuclear power plants are placed near the region. It is requested to understand the seismo-tectonic structures of the region, which may be crucial for mitigation of seismic hazards. Analysis of seismicity may be useful for illumination of fault structures. We investigate the focal mechanism solutions, ambient stress field, and spatial distribution of earthquakes. It is intriguing to note that the number of earthquakes increased since the 2011 Tohoku-Oki earthquake. We refined the hypocenters of 52 events using a velocity-searching hypocentral inversion method (VELHYPO). We determined the focal mechanism solutions of 25 events using a P polarity analysis and long period waveform inversion. The ambient stress field was inferred from the focal mechanism solutions. Strike-slip events occurred dominantly although the paleo-tectonic structures suggest the presence of thrust faults in the region. We observe that the compressional stress field is applied in ENE-WSW, which may be a combination of lateral compressions from the Pacific and Philippine Sea plates. The active strike-slip events and compressional stress field suggest reactivation of paleo-tectonic structures.

Tectonic activity evolution of the Scotia-Antarctic Plate boundary from mass transport deposit analysis

NASA Astrophysics Data System (ADS)

Pérez, Lara F.; Bohoyo, Fernando; Hernández-Molina, F. Javier; Casas, David; Galindo-Zaldívar, Jesús; Ruano, Patricia; Maldonado, Andrés.

2016-04-01

The spatial distribution and temporal occurrence of mass transport deposits (MTDs) in the sedimentary infill of basins and submerged banks near the Scotia-Antarctic plate boundary allowed us to decode the evolution of the tectonic activity of the relevant structures in the region from the Oligocene to present day. The 1020 MTDs identified in the available data set of multichannel seismic reflection profiles in the region are subdivided according to the geographic and chronological distributions of these features. Their spatial distribution reveals a preferential location along the eastern margins of the eastern basins. This reflects local deformation due to the evolution of the Scotia-Antarctic transcurrent plate boundary and the impact of oceanic spreading along the East Scotia Ridge (ESR). The vertical distribution of the MTDs in the sedimentary record evidences intensified regional tectonic deformation from the middle Miocene to Quaternary. Intensified deformation started at about 15 Ma, when the ESR progressively replaces the West Scotia Ridge (WSR) as the main oceanic spreading center in the Scotia Sea. Coevally with the WSR demise at about 6.5 Ma, increased spreading rates of the ESR and numerous MTDs were formed. The high frequency of MTDs during the Pliocene, mainly along the western basins, is also related to greater tectonic activity due to uplift of the Shackleton Fracture Zone by tectonic inversion and extinction of the Antarctic-Phoenix Ridge and involved changes at late Pliocene. The presence of MTDs in the southern Scotia Sea basins is a relevant indicator of the interplay between sedimentary instability and regional tectonics.

Effect of hyper- and hypocapnia on cerebral arterial compliance in normal subjects.

PubMed

Carrera, Emmanuel; Kim, Dong-Joo; Castellani, Gianluca; Zweifel, Christian; Smielewski, Peter; Pickard, John D; Czosnyka, Marek

2011-04-01

Changes in partial pressure of carbon dioxide (PaCO2) are associated with a decrease in cerebral blood flow (CBF) during hypocapnia and an increase in CBF during hypercapnia. However, the effects of changes in PaCO2 on cerebral arterial compliance (Ca) are unknown. We assessed the changes in Ca in 20 normal subjects using monitoring of arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). Cerebral arterial blood volume (CaBV) was extracted from CBFV. Ca was defined as the ratio between the pulse amplitudes of CaBV (AMPCaBV ) and ABP (AMPABP). All parameters were recorded during normo-, hyper-, and hypocapnia. During hypocapnia, Ca was significantly lower than during normocapnia (.10±.04 vs. .17±.06; P<.001) secondary to a decrease in AMPCaBV (1.3±.4 vs. 1.9±.5; P<.001) and a concomitant increase in AMPABP (13.8±3.4 vs. 11.6±1.7 mmHg; P<.001). During hypercapnia, there was no change in Ca compared with normocapnia. Ca was inversely correlated with the cerebrovascular resistance during hypo- (R2=0.86; P<.001), and hypercapnia (R2=0.61; P<.001). Using a new mathematical model, we have described a reduction of Ca during hypocapnia. Further studies are needed to determine whether Ca may be an independent predictor of outcome in pathological conditions. Copyright © 2009 by the American Society of Neuroimaging.

Chemical osmosis, reverse chemical osmosis, and the origin of subsurface brines

NASA Astrophysics Data System (ADS)

Graf, Donald L.

1982-08-01

Calculations using recently-tabulated values of density and osmotic coefficient for NaCl-H 2O indicate that overpressuring is more than adequate to overcome chemical osmosis and drive reverse chemical osmosis in sedimentary sequences. The best-demonstrated overpressuring mechanism is the rapid deposition of fine-grained sediments. The dehydration of gypsum contributes to overpressuring for brief time intervals at shallow depths, whereas water evolved during the protracted conversion of smectite to illite is probably a subordinate, but continuing contributor to overpressuring at greater depth. Occurrences of overpressuring in sedimentary sections older than Cretaceous indicate that post-depositional mechanisms such as tectonic compression and aquathermal pressuring must also operate. The latter may be of major importance in geothermal areas with adequate low-permeability seals, and a nontrivial contributor in areas of normal geothermal gradient because of shales that sharply decrease normal fluid flow. The strongest arguments for the importance to present-day brine compositions of membrane concentration of sea-water solutes are (1) the correlation of δD values of water molecules of pore fluid with those of local meteoric water, (2) the need for major sources of Mg 2+ and Cl - in apparently evaporite-free basins. Even where dissolution of halite is a major contributor of solute, reverse chemical osmosis still operates to leak relatively dilute water. Of the associated diagenetic chemical reactions, that of Mg 2+ with limestone to form dolomite is particularly effective in generating concentrated Cl - brines rich in Ca 2+. It decreases the concentration of Mg 2+, increases that of Ca 2+, and decreases those of both SO 42- and CO 32- by precipitating CaCO 3 and CaSO 4 because of the Ca 2+ common-ion effect.

Rotund versus skinny orogens: Well-nourished or malnourished gold?

USGS Publications Warehouse

Goldfarb, R.J.; Groves, D.I.; Gardoll, S.

2001-01-01

Orogenic gold vein deposits require a particular conjunction of processes to form and be preserved, and their global distribution can be related to broad-scale, evolving tectonic processes throughout Earth history. A heterogeneous distribution of formation ages for these mineral deposits is marked by two major Precambrian peaks (2800-2555 Ma and 2100-1800 Ma), a singular lack of deposits for 1200 m.y. (1800-600 Ma), and relatively continuous formation since then (after 600 Ma). The older parts of the distribution relate to major episodes of continental growth, perhaps controlled by plume-influenced mantle overturn events, in the hotter early Earth (ca. 1800 Ma or earlier). This worldwide process allowed preservation of gold deposits in cratons, roughly equidimensional, large masses of buoyant continental crust. Evolution to a less episodic, more continuous, modern-style plate tectonic regime led to the accretion of volcano-sedimentary complexes as progressively younger linear orogenic belts sorrounding the margins of the more buoyant cratons. The susceptibility of these linear belts to uplift and erosion can explain the overall lack of orogenic gold deposits at 1800-600 Ma, their exposure in 600-50 Ma orogens, the increasing importance of placer deposits back through the Phanerozoic since ca. 100 Ma, and the absence of gold deposits in orogenic belts younger than ca. 50 Ma.

Implanting Strong Spin-Orbit Coupling at Magnetoelectric Interfaces

DTIC Science & Technology

2017-12-19

one is polar. Because the broken inversion symmetry in the polar structure is driven by a combination of the Sr-Ca cation mismatch and the octahedral...ME coefficient without breaking the inversion symmetry manifest a large boost of the ME effect with strong spin-orbit coupling. Results on the polar... inversion center. These peaks are absent in the nonpolar structure and appear here due to the A-site ordering and the resulting inversion symmetry

Fault-slip inversions: Their importance in terms of strain, heterogeneity, and kinematics of brittle deformation

NASA Astrophysics Data System (ADS)

Riller, U.; Clark, M. D.; Daxberger, H.; Doman, D.; Lenauer, I.; Plath, S.; Santimano, T.

2017-08-01

Heterogeneous deformation is intrinsic in natural deformation, but often underestimated in the analysis and interpretation of mesoscopic brittle shear faults. Based on the analysis of 11,222 faults from two distinct tectonic settings, the Central Andes in Argentina and the Sudbury area in Canada, interpolation of principal strain directions and scaled analogue modelling, we revisit controversial issues of fault-slip inversions, collectively adhering to heterogeneous deformation. These issues include the significance of inversion solutions in terms of (1) strain or paleo-stress; (2) displacement, notably plate convergence; (3) local versus far-field deformation; (4) strain perturbations and (5) spacing between stations of fault-slip data acquisition. Furthermore, we highlight the value of inversions for identifying the kinematics of master fault zones in the absence of displaced geological markers. A key result of our assessment is that fault-slip inversions relate to local strain, not paleo-stress, and thus can aid in inferring, the kinematics of master faults. Moreover, strain perturbations caused by mechanical anomalies of the deforming upper crust significantly influence local principal strain directions. Thus, differently oriented principal strain axes inferred from fault-slip inversions in a given region may not point to regional deformation caused by successive and distinct deformation regimes. This outcome calls into question the common practice of separating heterogeneous fault-slip data sets into apparently homogeneous subsets. Finally, the fact that displacement vectors and principal strains are rarely co-linear defies the use of brittle fault data as proxy for estimating directions of plate-scale motions.

Buried paleo-sedimentary basins in the north-eastern Black Sea-Azov Sea area and tectonic implications (DOBRE-2)

NASA Astrophysics Data System (ADS)

Starostenko, Vitaly; Stephenson, Randell; Janik, Tomasz; Tolkunov, Anatoly

2014-05-01

A number of independent but inter-related projects carried out under the auspices of various national and international programmes in Ukraine including DARIUS were aimed at imaging the upper lithosphere, crustal and sedimentary basin architecture in the north-eastern Black Sea, southern Crimea and Kerch peninsulas and the Azov Sea. This region marks the transition from relatively undisturbed Precambrian European cratonic crust and lithosphere north of the Azov Sea to areas of significant Phanerozoic tectonics and basin development, in both extensional as well as compressional environments, to the south, including the eastern Black Sea rift, which is the main sedimentary basin of the study area. The wide-angle reflection and refraction (WARR) profile DOBRE-2, a Ukrainian national project with international participation (see below), overlapping some 115 km of the southern end of the DOBREfraction'99 profile (that crosses the intracratonic Donbas Foldbelt) in the north and running to the eastern Black Sea basin in the south, utilised on- and offshore recording and energy sources. It maps crustal velocity structure across the craton margin and documents, among other things, that the Moho deepens from 40 km to ~47 km to the southwest below the Azov Sea and Crimean-Caucasus deformed zone. A regional CDP seismic profile coincident with DOBRE-2, crossing the Azov Sea, Kerch Peninsula and the north-eastern Black Sea southwest to the Ukraine-Turkey border, acquired by Ukrgeofisika (the Ukrainian national geophysical company) reveals in its inferred structural relationships the ages of Cretaceous and younger extensional and subsequent basin inversion tectonic events as well as the 2D geometry of basement displacement associated with post mid-Eocene inversion. A direct comparison of the results of the WARR velocity model and the near-vertical reflection structural image has been made by converting the former into the time domain. The results dramatically demonstrate that there are major, rift-like, sedimentary basins underlying the area of the Azov Sea and the inverted north-eastern margin of the Black Sea. It can be speculated that one of these basins may represent the previously unknown western prolongation of the Jurassic-aged Greater Caucasus back-arc basin and that the other may be the legacy of earlier - Late Palaeozoic-Triassic - extensional tectonics in this area. Individuals (in alphabetical order) from each institution involved scientifically in DOBRE-2 (listed alphabetically according to country) include: H. Thybo (Department of Geography and Geology, University of Copenhagen, Denmark); A. Dannowski and E. Flüh (IFM-GEOMAR, Kiel, Germany); W. Czuba, A. Guterch and P. Środa (Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland); M. Grad (Institute of Geophysics, University of Warsaw, Warsaw, Poland); D. Gryn, K. Kolomiyets, O. Legostaeva, D. Lysynchuk, V. Omelchenko and O. Rusakov (Institute of Geophysics, National Academy of Sciences of Ukraine, Kyiv); M. Pobedash, N. Polyvach, G. Sydorenko and Z. Voitsytskyi (Ukrgeofisika, Kyiv, Ukraine); as well as the named co-authors of this presentation.

Effect of tip polarity on Kelvin probe force microscopy images of thin insulator CaF2 films on Si(111)

NASA Astrophysics Data System (ADS)

Yurtsever, Ayhan; Sugimoto, Yoshiaki; Fukumoto, Masaki; Abe, Masayuki; Morita, Seizo

2012-08-01

We investigate thin insulating CaF2 films on a Si (111) surface using a combination of noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM). Atomic-scale NC-AFM and KPFM images are obtained in different imaging modes by employing two different tip polarities. The KPFM image contrast and the distance-dependent variation of the local contact potential difference (LCPD) give rise to a tip-polarity-dependent contrast inversion. Ca2+ cations had a higher LCPD contrast than F- anions for a positively terminated tip, while the LCPD provided by a negatively charged tip gave a higher contrast for F- anions. Thus, this result implies that it is essential to determine the tip apex polarity to correctly interpret LCPD signals acquired by KPFM.

Characterising East Antarctic Lithosphere and its Rift Systems using Gravity Inversion

NASA Astrophysics Data System (ADS)

Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; Golynsky, A. V. Sasha; Rogozhina, Irina

2013-04-01

Since the International Geophysical Year (1957), a view has prevailed that East Antarctica has a relatively homogeneous lithospheric structure, consisting of a craton-like mosaic of Precambrian terranes, stable since the Pan-African orogeny ~500 million years ago (e.g. Ferracioli et al. 2011). Recent recognition of a continental-scale rift system cutting the East Antarctic interior has crystallised an alternative view of much more recent geological activity with important implications. The newly defined East Antarctic Rift System (EARS) (Ferraccioli et al. 2011) appears to extend from at least the South Pole to the continental margin at the Lambert Rift, a distance of 2500 km. This is comparable in scale to the well-studied East African rift system. New analysis of RadarSat data by Golynsky & Golynsky (2009) indicates that further rift zones may form widely distributed extension zones within the continent. A pilot study (Vaughan et al. 2012), using a newly developed gravity inversion technique (Chappell & Kusznir 2008) with existing public domain satellite data, shows distinct crustal thickness provinces with overall high average thickness separated by thinner, possibly rifted, crust. Understanding the nature of crustal thickness in East Antarctica is critical because: 1) this is poorly known along the ocean-continent transition, but is necessary to improve the plate reconstruction fit between Antarctica, Australia and India in Gondwana, which will also better define how and when these continents separated; 2) lateral variation in crustal thickness can be used to test supercontinent reconstructions and assess the effects of crystalline basement architecture and mechanical properties on rifting; 3) rift zone trajectories through East Antarctica will define the geometry of zones of crustal and lithospheric thinning at plate-scale; 4) it is not clear why or when the crust of East Antarctica became so thick and elevated, but knowing this can be used to test models of Cenozoic ice sheet formation and stability. References Chappell, A.R. & Kusznir, N.J. 2008. Three-dimensional gravity inversion for Moho depth at rifted continental margins incorporating a lithosphere thermal gravity anomaly correction. Geophysical Journal International, 174 (1), 1-13. Ferraccioli, F., Finn, C.A., Jordan, T.A., Bell, R.E., Anderson, L.M. & Damaske, D. 2011. East Antarctic rifting triggers uplift of the Gamburtsev Mountains Nature, 479, 388-392. Golynsky, A.V. & Golynsky, D.A. 2009. Rifts in the tectonic structure of East Antarctica (in Russian). Russian Earth Science Research in Antarctica, 2, 132-162. Vaughan, A.P.M., Kusznir, N.J., Ferraccioli, F. & Jordan, T.A.R.M. 2012. Regional heat-flow prediction for Antarctica using gravity inversion mapping of crustal thickness and lithosphere thinning. Geophysical Research Abstracts, 14, EGU2012-8095.

Megacycles of atmospheric carbon dioxide concentration correlate with fossil plant genome size.

PubMed

Franks, Peter J; Freckleton, Rob P; Beaulieu, Jeremy M; Leitch, Ilia J; Beerling, David J

2012-02-19

Tectonic processes drive megacycles of atmospheric carbon dioxide (CO(2)) concentration, c(a), that force large fluctuations in global climate. With a period of several hundred million years, these megacycles have been linked to the evolution of vascular plants, but adaptation at the subcellular scale has been difficult to determine because fossils typically do not preserve this information. Here we show, after accounting for evolutionary relatedness using phylogenetic comparative methods, that plant nuclear genome size (measured as the haploid DNA amount) and the size of stomatal guard cells are correlated across a broad taxonomic range of extant species. This phylogenetic regression was used to estimate the mean genome size of fossil plants from the size of fossil stomata. For the last 400 Myr, spanning almost the full evolutionary history of vascular plants, we found a significant correlation between fossil plant genome size and c(a), modelled independently using geochemical data. The correlation is consistent with selection for stomatal size and genome size by c(a) as plants adapted towards optimal leaf gas exchange under a changing CO(2) regime. Our findings point to the possibility that major episodes of change in c(a) throughout Earth history might have selected for changes in genome size, influencing plant diversification.

Neogene tectonic evolution and exhumation of the southern Ecuadorian Andes: a combined stratigraphy and fission-track approach

NASA Astrophysics Data System (ADS)

Steinmann, Michael; Hungerbühler, Dominik; Seward, Diane; Winkler, Wilfried

1999-06-01

Coastal marine and continental sedimentary facies of Middle to Late Miocene age are exposed in the Andes of southern Ecuador (Cuenca, Girón-Santa Isabel, Loja, Malacatos-Vilcabamba and Catamayo-Gonzanamá Basins). The chronostratigraphy of the basin series was established by zircon fission-track dating on a total of 120 tephra layers. Subsequently, the timing of tectonic events was estimated through the well-dated stratigraphic sequences and intervening unconformities. Sedimentation from ≈15 to 9 Ma (termed Pacific Coastal Stage) was dominantly of coastal marine type, extending over an area far greater than the present basin perimeters. It ended when a period of east-west-oriented compression at ≈9.5-8 Ma exhumed the region, and sedimentation was then restricted to smaller basins (termed Intermontane Stage). These Late Miocene continental sediments were for the first time sourced from the west in the rising Western Cordillera. Apatite fission-track analysis was applied to some of the tephras in the Cuenca Basin and also to the older (Eocene, 42-35 Ma) Quingeo Basin series in order to quantify the basin histories with respect to timing and amount of burial and later exhumation. In the Quingeo Basin burial of the oldest sediments reached temperatures of ˜100°C at 18 Ma, when they started to cool down during a period of exhumation. This process preceded the Pacific Coastal Stage development of the other basins. In the Cuenca Basin, the oldest sediments were buried to temperatures of ca. 120°C by 9 Ma, when a period of inversion began and a phase of erosion was dominant. This timing correlates well with that estimated from structural evidence. At ca. 6 Ma the cooling rate slowed down and maybe even reverted to a small increase in temperature until 3 Ma, when the final stages of exhumation took place. Assuming a geothermal gradient of 35°C/km, total uplift for this part for Ecuador is about 6100 m over the last 9 million years. Assuming a steady state continuous movement, this means a mean rock uplift rate of ˜0.7 mm/yr and a surface uplift of 0.3 mm/yr to the Present.

ANOMALOUS RELATIVE AR/CA CORONAL ABUNDANCES OBSERVED BY THE HINODE/EUV IMAGING SPECTROMETER NEAR SUNSPOTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doschek, G. A.; Warren, H. P.; Feldman, U.

2015-07-20

In determining the element abundance of argon (a high first ionization potential; FIP element) relative to calcium (a low FIP element) in flares, unexpectedly high intensities of two Ar xiv lines (194.40, 187.96 Å) relative to a Ca xiv line (193.87 Å) intensity were found in small (a few arcseconds) regions near sunspots in flare spectra recorded by the Extreme-ultraviolet Imaging Spectrometer on the Hinode spacecraft. In the most extreme case the Ar xiv line intensity relative to the Ca xiv intensity was 7 times the value expected from the photospheric abundance ratio, which is about 30 times the abundancemore » of argon relative to calcium in active regions, i.e., the measured Ar/Ca abundance ratio is about 10 instead of 0.37 as in active regions. The Ar xiv and Ca xiv lines are formed near 3.4 MK and have very similar contribution functions. This is the first observation of the inverse FIP effect in the Sun. Other regions show increases of 2–3 over photospheric abundances, or just photospheric abundances. This phenomenon appears to occur rarely and only over small areas of flares away from the regions containing multi-million degree plasma, but more work is needed to quantify the occurrences and their locations. In the bright hot regions of flares the Ar/Ca abundance ratio is coronal, i.e., the same as in active regions. In this Letter we show three examples of the inverse FIP effect.« less

Geochemistry of tectonically expelled fluids from the northern Coast ranges, Rumsey Hills, California, USA

USGS Publications Warehouse

Davisson, M.L.; Presser, T.S.; Criss, R.E.

1994-01-01

Tectonic compression has created abnormally high pressure on deep basinal fluids causing their expulsion from areally exposed Upper Cretaceous rock along the eastern margin of the California Coast ranges. The fluids emerge as near-neutral, perennial sodium chloride springs at high elevations with flow rates as high as 10 L per min. Higher spring discharges are more common around the exposure of a west-vergent fault propagation fold axis. Spring waters range from ~1000 to 27,000 mg/L TDS. The least saline water (??18O = -7.5???) closely represents local meteoric water that mixes with saline fluid (??18O = +5.3???) and forms a slope of ~3.5 on a ??D vs. ??18O plot. A Na (125 to 8000 mg/L) vs. Cl (150 to 17,000 mg/L) plot shows a linear dilution trend that extends close to, but below, the values for modern seawater. Calcium (75-3000 mg/L) is considerably enriched relative to seawater and forms a nonlinear trend with chloride. In detail, the "Na deficit," defined by the difference between the measured Na content and the Na concentration on a hypothetical seawater dilution line, is approximately balanced by the Ca excess, similarly defined by the seawater dilution line. This relationship strongly suggests that the fluid is diluted seawater that is being modified by active albitization of plagioclase at different depths. Simultaneous B and 18O enrichment of the fluids, accompanied by deuterium depletion, further suggest that the seawater modification is influenced by clay diagenesis. Bicarbonate and SiO2 concentrations show an inverse correlation with Cl, with most waters being saturated or slightly oversaturated with calcite and quartz at the discharge temperatures. Some freshwater springs with near-meteoric stable isotope values may represent mixing of young groundwater from perched aquifers, but in many cases, the freshwater springs emerge along the same structures and have the same perennial nature as the saline fluids, and expulsion of an older fresh groundwater component that is under abnormal fluid pressures cannot be ruled out. Basinal fluids elsewhere commonly show dilution trends with local meteoric water, and in the case of the Rumsey Hills, some of the dilute saline waters may indicate deep penetration of meteoric water (> 1 km) in the Pleistocene before the latest tectonic uplift. Geothermometry of the spring waters (maximum ~90??C) suggest an origin from as deep as 4.0 km. This depth is consistent with the depth of the core of a fault propagation anticline below the surface of the Rumsey Hills developed by active internal deformation of an east-tapering wedge beneath the southwestern Sacramento Valley. Active tectonic compression causes near-lithostatic fluid pressures in the shallow subsurface below the Rumsey Hills and volume strain within the core of the anticline that results in upward expulsion of the saline fluids from the indicated depths. ?? 1994.

A kinetic study of Ca-containing ions reacting with O, O2, CO2 and H2O: implications for calcium ion chemistry in the upper atmosphere.

PubMed

Broadley, Sarah; Vondrak, Tomas; Wright, Timothy G; Plane, John M C

2008-09-14

A series of gas-phase reactions involving molecular Ca-containing ions was studied by the pulsed laser ablation of a calcite target to produce Ca+ in a fast flow of He, followed by the addition of reagents downstream and detection of ions by quadrupole mass spectrometry. Most of the reactions that were studied are important for describing the chemistry of meteor-ablated calcium in the earth's upper atmosphere. The following rate coefficients were measured: k(CaO+ + O --> Ca+ + O2) = (4.2 +/- 2.8) x 10(-11) at 197 K and (6.3 +/- 3.0) x 10(-11) at 294 K; k(CaO+ + CO --> Ca+ + CO2, 294 K) = (2.8 +/- 1.5) x 10(-10); k(Ca+.CO2 + O2 --> CaO2+ + CO2, 294 K) = (1.2 +/- 0.5) x10(-10); k(Ca+.CO2 + H2O --> Ca+.H2O + CO2) = (13.0 +/- 4.0) x 10(-10); and k(Ca+.H2O + O2 --> CaO2+ + H2O, 294 K) = (4.0 +/- 2.5) x 10(-10) cm3 molecule(-1) s(-1). The quoted uncertainties are a combination of the 1 sigma standard errors in the kinetic data and the systematic errors in the models used to extract the rate coefficients. Rate coefficients were also obtained for the following recombination (also termed association) reactions in He bath gas: k(Ca+.CO2 + CO2 --> Ca+.(CO2)2, 294 K) = (2.6 +/- 1.0) x 10(-29); k(Ca+.H2O + H2O --> Ca+.(H2O)2) = (1.6 +/- 1.1) x 10(-27); and k(CaO2+ + O2 --> CaO2+.O2) < 1 x 10(-31) cm6 molecule(-2) s(-1). These recombination rate coefficients, as well as those for the ligand-switching reactions listed above, were then interpreted using a combination of high level quantum chemistry calculations and RRKM theory using an inverse Laplace transform solution of the master equation. The surprisingly slow reaction between CaO+ and O was explained using quantum chemistry calculations on the lowest 2A', 2A'' and 4A'' potential energy surfaces. These calculations indicate that reaction mostly occurs on the 2A' surface, leading to production of Ca+ (2S) + O2(1 Delta g). The importance of this reaction for controlling the lifetime of Ca+ in the upper mesosphere and lower thermosphere is then discussed.

Effect of Evaporation Time on Separation Performance of Polysulfone/Cellulose Acetate (PSF/CA) Membrane

NASA Astrophysics Data System (ADS)

Syahbanu, Intan; Piluharto, Bambang; Khairi, Syahrul; Sudarko

2018-01-01

Polysulfone and cellulose acetate are common material in separation. In this research, polysulfone/cellulose actetate (PSF/CA) blend membrane was prepared. The aim of this research was to study effect of evaporation time in casting of PSF/CA membrane and its performance in filtration. CA was obtained by acetylation process of bacterial cellulose (BC) from fermentation of coconut water. Fourier Transform Infra Red (FTIR) Spectroscopy was used to examine functional groups of BC, CA and commercial cellulose acetate. Subtitution of acetyl groups determined by titration method. Blend membranes were prepared through phase inversion technique in which composition of PSF/PEG/CA/NMP(%w) was 15/5/5/75. Polyethyleneglycol (PEG) and N-methyl-2-pyrrolidone (NMP) were act as pore forming agent and solvent, respectively. Variation of evaporation times were used as parameter to examine water uptake, flux, and morphology of PSF/CA blend membranes. FTIR spectra of CA show characteristic peak of acetyl group at 1220 cm-1 indicated that BC was acetylated succesfully. Degree of subtitution of BCA was found at 2.62. Highest water flux was performed at 2 bar obtained at 106.31 L.m-2.h-1 at 0 minute variation, and decrease as increasing evaporation time. Morphology of PSF/BCA blend membranes were investigated by Scanning Electron Microscopy (SEM) showed that porous asymetric membrane were formed.

Geochemistry of Early Paleozoic boninites from the Central Qilian block, Northwest China: Constraints on petrogenesis and back-arc basin development

NASA Astrophysics Data System (ADS)

Gao, Zhong; Zhang, Hong-Fei; Yang, He; Luo, Bi-Ji; Guo, Liang; Xu, Wang-Chun; Pan, Fa-Bin

2018-06-01

Early Paleozoic boninites occur in the Central Qilian orogenic belt, Northwest China. Their petrogenesis provides insights into lithosphere process and tectonic evolution of the Qilian block. In this paper, we carry out a study of geochronological, geochemical and Sr-Nd isotopic compositions for the Early Paleozoic boninites in the Lajishan area of the Central Qilian block. The Lajishan boninites (∼483 Ma) have high Al2O3/TiO2 (36.7-64.7) and CaO/TiO2 (31.1-49.6) ratios, and high MgO (7.86-10.47 wt%), Cr (439-599 ppm) and Ni (104-130 ppm) contents, indicating that the boninites result from a refractory mantle source. They are depleted in high field-strength elements (HFSE) and enriched in large ion lithophile elements (LILE), coupled with slightly high initial 87Sr/86Sr values of 0.7059-0.7074 and low εNd(t) values of -1.05 to +2.66, indicating that the mantle source was metasomatized by subducted slab-derived components. We found that an assemblage of low-Ca group and high-Ca group boninites occurred in the Lajishan belt. The high-Ca group boninites were derived from relatively fertile mantle with slightly higher melting degree, whereas the low-Ca group boninites were generated by partial melting of more refractory mantle wedge peridotites with slightly lower melting degree. The assemblage of low-Ca group and high-Ca group boninites reveals that the low-Ca group boninites were generated by the further melting of the more refractory mantle source after the segregation of the high-Ca group boninitic magmas in response to the back-arc basin opening. In the light of reported boninites worldwide, a diagram of Zr/Y vs. CaO/Al2O3 is used to identify boninites in fore-arc and back-arc regions. We suggest that the Lajishan boninites represent the products of back-arc basin development in response to the northward subduction of the Qaidam-West Qinling ocean slab.

The Haselgebirge evaporitic mélange in central Northern Calcareous Alps (Austria): Part of the Permian to Lower Triassic rift of the Meliata ocean?

PubMed

Schorn, Anja; Neubauer, Franz; Genser, Johann; Bernroider, Manfred

2013-01-11

For the reconstruction of Alpine tectonics of the Eastern Alps, the evaporitic Permian to Lower Triassic Haselgebirge Formation plays a key role in (1) the origin of Haselgebirge bearing nappes, (2) the inclusion of magmatic and metamorphic rocks revealing tectonic processes not preserved in other units, and (3) the debated mode of emplacement of the nappes, namely gravity-driven or tectonic. Within the Moosegg quarry of the central Northern Calcareous Alps gypsum/anhydrite bodies are tectonically mixed with lenses of sedimentary rocks and decimeter- to meter-sized tectonic clasts of plutonic and subvolcanic rocks and rare metamorphics. We examined various types of (1) widespread biotite-diorite, meta-syenite, (2) meta-dolerite and rare ultramafic rocks (serpentinite, pyroxenite) as well as (3) rare metamorphic banded meta-psammitic schists and meta-doleritic blueschists. The apparent 40 Ar/ 39 Ar biotite ages from three biotite-diorite, meta-dolerite and meta-doleritic blueschist samples with variable composition and fabrics range from 248 to 270 Ma (e.g., 251.2 ± 1.1 Ma) indicating a Permian age of cooling after magma crystallisation or metamorphism. The chemical composition of biotite-diorite and meta-syenite indicates an alkaline trend interpreted to represent a rift-related magmatic suite. These, as well as Permian to Jurassic sedimentary rocks, were incorporated during Cretaceous nappe emplacement forming the sulphatic Haselgebirge mélange. The scattered 40 Ar/ 39 Ar white mica ages of a meta-doleritic blueschist (of N-MORB origin) and banded meta-psammitic schist are ca. 349 and 378 Ma, respectively, proving the Variscan age of pressure-dominated metamorphism. These ages are similar to detrital white mica ages reported from the underlying Rossfeld Formations, indicating a close source-sink relationship. According to our new data, the Haselgebirge bearing nappe was transported over the Lower Cretaceous Rossfeld Formations, which include many clasts derived from the Haselgebirge Formation and its exotic blocks deposited in front of the incoming nappe comprising the Haselgebirge Formation.

3-D Inversion of the MT EarthScope Data, Collected Over the East Central United States

NASA Astrophysics Data System (ADS)

Gribenko, A. V.; Zhdanov, M. S.

2017-12-01

The magnetotelluric (MT) data collected as a part of the EarthScope project provided a unique opportunity to study the conductivity structure of the deep interior of the North American continent. Besides the scientific value of the recovered subsurface models, the data also allowed inversion practitioners to test the robustness of their algorithms applied to regional long-period data. In this paper, we present the results of MT inversion of a subset of the second footprint of the MT data collection covering the East Central United States. Our inversion algorithm implements simultaneous inversion of the full MT impedance data both for the 3-D conductivity distribution and for the distortion matrix. The distortion matrix provides the means to account for the effect of the near-surface geoelectrical inhomogeneities on the MT data. The long-period data do not have the resolution for the small near-surface conductivity anomalies, which makes an application of the distortion matrix especially appropriate. The determined conductivity model of the region agrees well with the known geologic and tectonic features of the East Central United States. The conductivity anomalies recovered by our inversion indicate a possible presence of the hot spot track in the area.

Transposition of foliations and superposition of lineations during polyphase deformation in the Nevado-Filabride complex: tectonic implications

NASA Astrophysics Data System (ADS)

Ruiz-Fuentes, Alejandro; Aerden, Domingo G. A. M.

2018-01-01

Detailed structural analysis in a ca. 80 km2 area of the western Nevado-Filabride complex (Betic Cordillera) reveals a heterogeneous internal structure characterized by multiple cross-cutting foliations and lineations that locally transpose earlier ones. The large-scale geometry of these fabrics conflicts with continuous westward to south-westward tectonic transport related to thrusting or crustal extension, and mismatches a previously inferred extensional detachment in the area. Multiple crenulation lineations can be distinguished in the field and correlated with five foliation intersection axes (FIA1-5) preserved in garnet and plagioclase porphyroblasts of the western Sierra Nevada. These indicate crustal shortening in different directions associated with vertical foliation development and intermitted stages of gravitational collapse producing horizontal foliations. The large spread of lineation- and fold-axes trends in the Nevado-Filabride complex results from the mixed presence of multiple generations of these structures whose distinction is critical for tectonic models. The five principal FIA trends remarkably match successive vectors of relative Africa-Iberia plate motion since the Eocene, suggesting that deformation of the Nevado-Filabride took place during this period, although peak metamorphism in at least some of its parts was reached as late as the Middle Miocene.

Optimization of data analysis for the in vivo neutron activation analysis of aluminum in bone.

PubMed

Mohseni, H K; Matysiak, W; Chettle, D R; Byun, S H; Priest, N; Atanackovic, J; Prestwich, W V

2016-10-01

An existing system at McMaster University has been used for the in vivo measurement of aluminum in human bone. Precise and detailed analysis approaches are necessary to determine the aluminum concentration because of the low levels of aluminum found in the bone and the challenges associated with its detection. Phantoms resembling the composition of the human hand with varying concentrations of aluminum were made for testing the system prior to the application to human studies. A spectral decomposition model and a photopeak fitting model involving the inverse-variance weighted mean and a time-dependent analysis were explored to analyze the results and determine the model with the best performance and lowest minimum detection limit. The results showed that the spectral decomposition and the photopeak fitting model with the inverse-variance weighted mean both provided better results compared to the other methods tested. The spectral decomposition method resulted in a marginally lower detection limit (5μg Al/g Ca) compared to the inverse-variance weighted mean (5.2μg Al/g Ca), rendering both equally applicable to human measurements. Copyright © 2016 Elsevier Ltd. All rights reserved.

Eocene to mid-Pliocene landscape evolution in Scandinavia inferred from offshore sediment volumes and pre-glacial topography using inverse modelling

NASA Astrophysics Data System (ADS)

Pedersen, Vivi K.; Braun, Jean; Huismans, Ritske S.

2018-02-01

The origin of high topography in Scandinavia is highly debated, both in terms of its age and the underlying mechanism for its formation. Traditionally, the current high topography is assumed to have formed by several Cenozoic (mainly Neogene) phases of surface uplift and dissection of an old peneplain surface. These same surface uplift events are suggested to explain the increased deposition observed in adjacent offshore basins on the Norwegian shelf and in the North Sea. However, more recently it has been suggested that erosion and isostatic rock uplift of existing topography may also explain the recent evolution of topography in Scandinavia. For this latter view, the increased sedimentation towards the present is assumed to be a consequence of a climate related increase in erosion. In this study we explore whether inverse modelling of landscape evolution can give new insight into Eocene to mid-Pliocene (54-4 Ma) landscape evolution in the Scandinavian region. We do this by combining a highly efficient forward-in-time landscape evolution model (FastScape) with an optimization scheme suitable for non-linear inverse problems (the neighbourhood algorithm - NA). To limit our approach to the fluvial regime, we exclude the most recent mid-Pliocene-Quaternary time period where glacial erosion processes are expected to dominate landscape evolution. The "goodness" of our landscape evolution models is evaluated using i) sediment fluxes based on decompacted offshore sediment volumes and ii) maximum pre-glacial topography from a mid-Pliocene landscape, reconstructed using geophysical relief and offshore sediment volumes from the mid-Pliocene-Quaternary. We find several tested scenarios consistent with the offshore sediment record and the maximum elevation for our reconstructed pre-glacial (mid-Pliocene) landscape reconstruction, including: I) substantial initial topography ( 2 km) at 54 Ma and no induced tectonic rock uplift, II) the combination of some initial topography ( 1.1 km) at 54 Ma and minor continued rock uplift (< 0.04 mm/yr) until 4 Ma, and III) a two-phased tectonic rock uplift of an initially low topography ( 0.1 km). However, out of these, only scenario I (no tectonic rock uplift) matches large-scale characteristics of our reconstructed pre-glacial (mid-Pliocene) topography well. Our preferred model for Eocene to mid-Pliocene landscape evolution in Scandinavia is therefore one where high topography ( 2 km) has existed throughout the time interval from 54 to 4 Ma. We do not find several phases of peneplain surface uplift necessary to explain offshore sediment volumes and large-scale topographic patterns. On the contrary, extensive peneplain dissection seems inconsistent with the low rates of erosion we infer based on the offshore sediment volumes.

Construction of the seismic wave-speed model by adjoint tomography beneath the Japanese metropolitan area

NASA Astrophysics Data System (ADS)

Miyoshi, Takayuki

2017-04-01

The Japanese metropolitan area has high risks of earthquakes and volcanoes associated with convergent tectonic plates. It is important to clarify detail three-dimensional structure for understanding tectonics and predicting strong motion. Classical tomographic studies based on ray theory have revealed seismotectonics and volcanic tectonics in the region, however it is unknown whether their models reproduce observed seismograms. In the present study, we construct new seismic wave-speed model by using waveform inversion. Adjoint tomography and the spectral element method (SEM) were used in the inversion (e.g. Tape et al. 2009; Peter et al. 2011). We used broadband seismograms obtained at NIED F-net stations for 140 earthquakes occurred beneath the Kanto district. We selected four frequency bands between 5 and 30 sec and used from the seismograms of longer period bands for the inversion. Tomographic iteration was conducted until obtaining the minimized misfit between data and synthetics. Our SEM model has 16 million grid points that covers the metropolitan area of the Kanto district. The model parameters were the Vp and Vs of the grid points, and density and attenuation were updated to new values depending on new Vs in each iteration. The initial model was assumed the tomographic model (Matsubara and Obara 2011) based on ray theory. The source parameters were basically used from F-net catalog, while the centroid times were inferred from comparison between data and synthetics. We simulated the forward and adjoint wavefields of each event and obtained Vp and Vs misfit kernels from their interaction. Large computation was conducted on K computer, RIKEN. We obtained final model (m16) after 16 iterations in the present study. For the waveform improvement, it is clearly shown that m16 is better than the initial model, and the seismograms especially improved in the frequency bands of longer than 8 sec and changed better for seismograms of the events occurred at deeper than a depth of 30 km. We found distinct low wave-speed patterns in S-wave structure. One of the patterns extends in the E-W direction around a depth of 40 km. This zone was interpreted as the serpentinized mantle above the Philippine Sea slab (e.g. Kamiya and Kobayashi 2000). We also obtained the low wave-speed zone around the depth of 5 km. It seems this area extends along the Median tectonic line and this area is correspond to the sedimentary layer. We thank the NIED for providing seismic data, and also thank the researchers for providing the SPECFEM Cartesian program package.

Dietary, supplement, and adipose tissue tocopherol levels in relation to prostate cancer aggressiveness among African and European Americans: The North Carolina-Louisiana Prostate Cancer Project (PCaP).

PubMed

Antwi, Samuel O; Steck, Susan E; Su, L Joseph; Hébert, James R; Zhang, Hongmei; Fontham, Elizabeth T H; Smith, Gary J; Bensen, Jeannette T; Mohler, James L; Arab, Lenore

2015-09-01

Controversies remain over the safety and efficacy of vitamin E (i.e., α-tocopherol) supplementation use for the prevention of prostate cancer (CaP); however, associations of different tocopherol forms and CaP aggressiveness have yet to be examined. This study examined whether food intake of tocopherols, vitamin E supplement use, and adipose tissue biomarkers of tocopherol were associated with CaP aggressiveness among African-American (AA, n = 1,023) and European-American (EA, n = 1,079) men diagnosed with incident CaP. Dietary tocopherols were estimated from a food frequency questionnaire, supplement use from questionnaire/inventory, and biomarkers from abdominal adipose samples measured using high-performance liquid chromatography. Odds ratios (ORs) and 95% confidence intervals (95%CIs) were estimated from logistic regression comparing high-aggressive CaP to low/intermediate aggressive CaP, adjusting for covariates. Dietary intakes of α-and δ-tocopherol were related inversely to CaP aggressiveness among EAs [OR (95%CI), highest versus lowest quartile: α-tocopherol, 0.34 (0.17-0.69), P(trend)  = 0.006; δ-tocopherol, 0.45 (0.21-0.95) P(trend)  = 0.007]. Inverse associations between dietary and supplemental α-tocopherol and CaP aggressiveness were observed among AAs, though these did not reach statistical significance [OR (95%CI), highest versus lowest quartile: dietary α-tocopherol, 0.58 (0.28-1.19), P(trend)  = 0.20; supplemental α-tocopherol, 0.64 (0.31-1.21) P(trend)  = 0.15]. No significant association was observed between adipose tocopherol levels and CaP aggressiveness [OR (95%CI), highest versus lowest quartiles of α-tocopherol for EAs 1.43 (0.66-3.11) and AAs 0.66 (0.27-1.62)]. The inverse associations observed between dietary sources of tocopherols and CaP aggressiveness suggests a beneficial role of food sources of these tocopherols in CaP aggressiveness. © 2015 Wiley Periodicals, Inc.

Miocene tectonics of the Western Alboran domain: from mantle extensional exhumation to westward thrusting

NASA Astrophysics Data System (ADS)

Gueydan, F.; Frasca, G.; Brun, J. P.

2015-12-01

In the frame of the Africa-Europe convergence, the Mediterranean tectonic system presents a complex interaction between subduction rollback and upper-plate deformation during the Tertiary. The western Mediterranean is characterized by the exhumation of the largest subcontinental mantle massif worldwide (the Ronda Peridotite) and a narrow arcuate geometryacross the Gibraltar arc within the Betic-Rif belt (the internal part being called the Alboran domain), where the relationship between slab dynamics and surface tectonics is not well understood. New structural and geochronological data are used to argue for 1/ hyperstrechting of the continental lithosphere allowing extensional mantle exhumation to shallow depths, followed by 2/ lower miocene thrusting. Two Lower Miocene E-W-trending strike-slip corridors played a major role in the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60°-trending thrusts and N140°-trending normal faults developed simultaneously during dextral strike-slip simple shear. The inferred continuous westward translation of the Alboran Domain is accommodated by a major E-W-trending lateral ramp (strike-slip) and a N60°-trending frontal thrust. At lithosphere-scale, we interpret the observed deformation pattern as the upper-plate expression of a lateral slab tear and of its westward propagation since Lower Miocene. The crustal emplacement of the Ronda Peridotites occurred at the onset of this westward motion.The Miocene tectonics of the western Alboran is therefore marked by the inversion of a continental rift, triggered by shortening of the upper continental plate and accommodated by E-W dextral strike-slip corridors. During thrusting and westward displacement of the Alboran domain with respect to Iberia, the hot upper plate, which involved the previously exhumed sub-continental mantle, underwent fast cooling.

Origin of a crustal splay fault and its relation to the seismogenic zone and underplating at the erosional north Ecuador-south Colombia oceanic margin

NASA Astrophysics Data System (ADS)

Collot, J.-Y.; Agudelo, W.; Ribodetti, A.; Marcaillou, B.

2008-12-01

Splay faults within accretionary complexes are commonly associated with the updip limit of the seismogenic zone. Prestack depth migration of a multichannel seismic line across the north Ecuador-south Colombia oceanic margin images a crustal splay fault that correlates with the seaward limit of the rupture zone of the 1958 (Mw 7.7) tsunamogenic subduction earthquake. The splay fault separates 5-6.6 km/s velocity, inner wedge basement rocks, which belong to the accreted Gorgona oceanic terrane, from 4 to 5 km/s velocity outer wedge rocks. The outer wedge is dominated by basal tectonic erosion. Despite a 3-km-thick trench fill, subduction of 2-km-high seamount prevented tectonic accretion and promotes basal tectonic erosion. The low-velocity and poorly reflective subduction channel that underlies the outer wedge is associated with the aseismic, décollement thrust. Subduction channel fluids are expected to migrate upward along splay faults and alter outer wedge rocks. Conversely, duplexes are interpreted to form from and above subducting sediment, at ˜14- to 15-km depths between the overlapping seismogenic part of the splay fault and the underlying aseismic décollement. Coeval basal erosion of the outer wedge and underplating beneath the apex of inner wedge control the margin mass budget, which comes out negative. Intraoceanic basement fossil listric normal faults and a rift zone inverted in a flower structure reflect the evolution of the Gorgona terrane from Cretaceous extension to likely Eocene oblique compression. The splay faults could have resulted from tectonic inversion of listric normal faults, thus showing how inherited structures may promote fluid flow across margin basement and control seismogenesis.

GPS Imaging of Sierra Nevada Uplift

NASA Astrophysics Data System (ADS)

Hammond, W. C.; Blewitt, G.; Kreemer, C.

2015-12-01

Recent improvements in the scope and precision of GPS networks across California and Nevada have allowed for uplift of the Sierra Nevada to be observed directly. Much of the signal, in the range of 1 to 2 mm/yr, has been attributed to lithospheric scale rebound following massive groundwater withdrawal in the San Joaquin Valley in southern California, exacerbated by drought since 2011. However, natural tectonic deformation associated with long term uplift of the range may also contribute to the observed signal. We have developed new algorithms that enhance the signal of Sierra Nevada uplift and improve our ability to interpret and separate natural tectonic signals from anthropogenic contributions. We apply our new Median Interannual Difference Adjusted for Skewness (MIDAS) algorithm to the vertical times series and a inverse distance-weighted median spatial filtering and Delaunay-based interpolation to despeckle the rate map. The resulting spatially continuous vertical rate field is insensitive to outliers and steps in the GPS time series, and omits isolated features attributable to unstable stations or unrepresentative rates. The resulting vertical rate field for California and Nevada exhibits regionally coherent signals from the earthquake cycle including interseismic strain accumulation in Cascadia, postseismic relaxation of the mantle from recent large earthquakes in central Nevada and southern California, groundwater loading changes, and tectonic uplift of the Sierra Nevada and Coast Ranges. Uplift of the Sierra Nevada extends from the Garlock Fault in the south to an indefinite boundary in the north near the latitude of Mt. Lassen to the eastern Sierra Nevada range front in Owen's Valley. The rates transition to near zero in the southern Walker Lane. The eastern boundary of uplift coincides with the highest strain rates in the western Great Basin, suggesting higher normal fault slip rates and a component of tectonic uplift of the Sierra Nevada.

Cellulose acetate-based SiO2/TiO2 hybrid microsphere composite aerogel films for water-in-oil emulsion separation

NASA Astrophysics Data System (ADS)

Yang, Xue; Ma, Jianjun; Ling, Jing; Li, Na; Wang, Di; Yue, Fan; Xu, Shimei

2018-03-01

The cellulose acetate (CA)/SiO2-TiO2 hybrid microsphere composite aerogel films were successfully fabricated via water vapor-induced phase inversion of CA solution and simultaneous hydrolysis/condensation of 3-aminopropyltrimethoxysilane (APTMS) and tetrabutyl titanate (TBT) at room temperature. Micro-nano hierarchical structure was constructed on the surface of the film. The film could separate nano-sized surfactant-stabilized water-in-oil emulsions only under gravity. The flux of the film for the emulsion separation was up to 667 L m-2 h-1, while the separation efficiency was up to 99.99 wt%. Meanwhile, the film exhibited excellent stability during multiple cycles. Moreover, the film performed excellent photo-degradation performance under UV light due to the photocatalytic ability of TiO2. Facile preparation, good separation and potential biodegradation maked the CA/SiO2-TiO2 hybrid microsphere composite aerogel films a candidate in oil/water separation application.

Upper crustal structure of central Java, Indonesia, from transdimensional seismic ambient noise tomography

NASA Astrophysics Data System (ADS)

Zulfakriza, Z.; Saygin, E.; Cummins, P. R.; Widiyantoro, S.; Nugraha, A. D.; Lühr, B.-G.; Bodin, T.

2014-04-01

Delineating the crustal structure of central Java is crucial for understanding its complex tectonic setting. However, seismic imaging of the strong heterogeneity typical of such a tectonically active region can be challenging, particularly in the upper crust where velocity contrasts are strongest and steep body wave ray paths provide poor resolution. To overcome these difficulties, we apply the technique of ambient noise tomography (ANT) to data collected during the Merapi Amphibious Experiment (MERAMEX), which covered central Java with a temporary deployment of over 120 seismometers during 2004 May-October. More than 5000 Rayleigh wave Green's functions were extracted by cross-correlating the noise simultaneously recorded at available station pairs. We applied a fully non-linear 2-D Bayesian probabilistic inversion technique to the retrieved traveltimes. Features in the derived tomographic images correlate well with previous studies, and some shallow structures that were not evident in previous studies are clearly imaged with ANT. The Kendeng Basin and several active volcanoes appear with very low group velocities, and anomalies with relatively high velocities can be interpreted in terms of crustal sutures and/or surface geological features.

Estimating Stresses, Fault Friction and Fluid Pressure from Topography and Coseismic Slip Models

NASA Astrophysics Data System (ADS)

Styron, R. H.; Hetland, E. A.

2014-12-01

Stress is a first-order control on the deformation state of the earth. However, stress is notoriously hard to measure, and researchers typically only estimate the directions and relative magnitudes of principal stresses, with little quantification of the uncertainties or absolute magnitude. To improve upon this, we have developed methods to constrain the full stress tensor field in a region surrounding a fault, including tectonic, topographic, and lithostatic components, as well as static friction and pore fluid pressure on the fault. Our methods are based on elastic halfspace techniques for estimating topographic stresses from a DEM, and we use a Bayesian approach to estimate accumulated tectonic stress, fluid pressure, and friction from fault geometry and slip rake, assuming Mohr-Coulomb fault mechanics. The nature of the tectonic stress inversion is such that either the stress maximum or minimum is better constrained, depending on the topography and fault deformation style. Our results from the 2008 Wenchuan event yield shear stresses from topography up to 20 MPa (normal-sinistral shear sense) and topographic normal stresses up to 80 MPa on the faults; tectonic stress had to be large enough to overcome topography to produce the observed reverse-dextral slip. Maximum tectonic stress is constrained to be >0.3 * lithostatic stress (depth-increasing), with a most likely value around 0.8, trending 90-110°E. Minimum tectonic stress is about half of maximum. Static fault friction is constrained at 0.1-0.4, and fluid pressure at 0-0.6 * total pressure on the fault. Additionally, the patterns of topographic stress and slip suggest that topographic normal stress may limit fault slip once failure has occurred. Preliminary results from the 2013 Balochistan earthquake are similar, but yield stronger constraints on the upper limits of maximum tectonic stress, as well as tight constraints on the magnitude of minimum tectonic stress and stress orientation. Work in progress on the Wasatch fault suggests that maximum tectonic stress may also be able to be constrained, and that some of the shallow rupture segmentation may be due in part to localized topographic loading. Future directions of this work include regions where high relief influences fault kinematics (such as Tibet).

Subsidence transition during the post-rift stage of the Dongpu Sag, Bohai Bay Basin, NE China: A new geodynamic model

NASA Astrophysics Data System (ADS)

Xu, Han; Wang, Xin-Wen; Yan, Dan-Ping; Qiu, Liang

2018-06-01

The Dongpu Sag, located in the Bohai Bay Basin, NE China, is a Cenozoic continental rift basin. The post-rift evolution of the Dongpu Sag is associated with the development of petroleum reservoirs and has implications for Neogene-Quaternary basin evolution along the eastern margin of Eurasia. To determine the nature and origin of post-rift subsidence in the Dongpu Sag, we apply backstripping, modified strain-rate inversion, and revised finite extension modelling techniques, using data from 14 real and synthetic wells that are intersected by three seismic lines. Our results reveal discrepancies by subsidence based on backstripping of well data (the observed subsidence) minus that predicted by modified strain-rate inversion and revised finite extension modelling (the predicted subsidence). During the Miocene, the observed subsidence was smaller than the predicted subsidence, leaving negative discrepancies referred to here as "insufficient subsidence" ranging from -343 to -96 m. In contrast, during the Pliocene-Quaternary the observed subsidence was greater than the predicted subsidence by +123 to +407 m, which left positive discrepancies referred to as "over-sufficient subsidence". Therefore, we infer a transition from insufficient to over-sufficient subsidence during the post-rift stage. Normal faulting that started at ca. 5.3 Ma is estimated to have produced only ∼20% of the over-sufficient subsidence. Therefore, the remaining over-sufficient subsidence, as well as the preceding insufficient subsidence and the transition between the two, were likely controlled by lithosphere processes. We propose a new tectonic model in which variations in the conditions (e.g. rate, direction, and angle) associated with subduction of the Pacific plate resulted in a change of heat flow decreasing from a linear to a curvilinear pattern, leading to a transition from insufficient to over-sufficient subsidence.

Inverse analysis of giant macroscopic negative thermal expansion of Ca2RuO4‑ y ceramics based on elasticity and structural topology optimization

NASA Astrophysics Data System (ADS)

Takezawa, Akihiro; Takenaka, Koshi; Zhang, Xiaopeng

2018-05-01

Ca2RuO4‑ y ceramics exhibit a large volumetric negative thermal expansions (NTE), although the crystallographic volume contraction on heating is much smaller than the NTE. Therefore, we examine the differences in the mechanisms underlying the volumetric thermal expansion for ruthenate ceramics and crystals in the context of the elasticity. We identify the possible microstructure of ruthenate ceramics composed of crystal grains and cavities using structural topology optimization. We conclude that the measured large volumetric NTE of ruthenate ceramics is certainly possible via anisotropic crystallographic thermal expansion through an elastic mechanism.

Aeromagnetic anomalies reveal the link between magmatism and tectonics during the early formation of the Canary Islands.

PubMed

Blanco-Montenegro, Isabel; Montesinos, Fuensanta G; Arnoso, José

2018-01-08

The 3-D inverse modelling of a magnetic anomaly measured over the NW submarine edifice of the volcanic island of Gran Canaria revealed a large, reversely-magnetized, elongated structure following an ENE-WSW direction, which we interpreted as a sill-like magmatic intrusion emplaced during the submarine growth of this volcanic island, with a volume that could represent up to about 20% of the whole island. The elongated shape of this body suggests the existence of a major crustal fracture in the central part of the Canary Archipelago which would have favoured the rapid ascent and emplacement of magmas during a time span from 0.5 to 1.9 My during a reverse polarity chron of the Earth's magnetic field prior to 16 Ma. The agreement of our results with those of previous gravimetric, seismological and geodynamical studies strongly supports the idea that the genesis of the Canary Islands was conditioned by a strike-slip tectonic framework probably related to Atlas tectonic features in Africa. These results do not contradict the hotspot theory for the origin of the Canary magmatism, but they do introduce the essential role of regional crustal tectonics to explain where and how those magmas both reached the surface and built the volcanic edifices.

Solid earth as a recycling systems and the lateral growth of Precambrian North America

NASA Technical Reports Server (NTRS)

Veizer, Jan

1988-01-01

If plotted on mass vs time diagrams, geologic entities (for example, continental and oceanic crust, sediments, and mineral resources) display an exponential (power law) relationship, with entity per unit time increasing toward the present. This relationship is consistent with the concept of recycling and can be simulated mathematically. The approach is based on the plate tectonic theory and considers area-age or mass-age distributions of crystalline basement and sediments for major global tectonic realms. Each tectonic realm is characterized by a specific lifespan, which is an inverse function of its recycling rate. The estimated average half-area of half-mass ages are given. The corresponding parameters for continental crust are 690 Ma for K/Ar, and approximately 1200 Ma for Rb/St and U-Th/Pb dating pairs. Tectonic diversity preserved in the geologic record is therefore a function of time, with oceanic tectonic realms, because of their rapid recycling, underrepresented in the rocks older than approximately 300 Ma. The Sm/Nd isotopic systematic of sediments suggest that, for a near steady-state post-Archean sedimentary mass, recycling is approximately 90 + or - 5 percent cannibalistic. This yields an estimated upper limit on crust-mantle exchange via sediment subduction of approximately 1.1 + or - 0.5 x 10 g a(sup -1) considerably less than demanded by isotopic constraints. The discrepancy may indicate the existence of additional loci, such as orogenic belts, for significant crust-mantle interaction.

Tectonic stress regime in the 2003-2004 and 2012-2015 earthquake swarms in the Ubaye Valley, French Alps

NASA Astrophysics Data System (ADS)

Fojtíková, Lucia; Vavryčuk, Václav

2018-02-01

We study two earthquake swarms that occurred in the Ubaye Valley, French Alps within the past decade: the 2003-2004 earthquake swarm with the strongest shock of magnitude ML = 2.7, and the 2012-2015 earthquake swarm with the strongest shock of magnitude ML = 4.8. The 2003-2004 seismic activity clustered along a 9-km-long rupture zone at depth between 3 and 8 km. The 2012-2015 activity occurred a few kilometres to the northwest from the previous one. We applied the iterative joint inversion for stress and fault orientations developed by Vavryčuk (2014) to focal mechanisms of 74 events of the 2003-2004 swarm and of 13 strongest events of the 2012-2015 swarm. The retrieved stress regime is consistent for both seismic activities. The σ 3 principal axis is nearly horizontal with azimuth of 103°. The σ 1 and σ 2 principal axes are inclined and their stress magnitudes are similar. The active faults are optimally oriented for shear faulting with respect to tectonic stress and differ from major fault systems known from geological mapping in the region. The estimated low value of friction coefficient at the faults 0.2-0.3 supports an idea of seismic activity triggered or strongly affected by presence of fluids.

Application of MAGSAT to lithospheric modeling in South America

NASA Technical Reports Server (NTRS)

Keller, G. R.; Lidiak, E. G. (Principal Investigator)

1982-01-01

Progress continues on all aspects of the project. The prime emphasis is on the Rayleigh wave study and determination of both group and phase velocity dispersion is almost complete. Existing data sets were prepared for inversion. A paper on the relation of MAGSAT anomalies to the main tectonic provinces of South America was delivered at the annual meeting of the Society of Exploration Geophysicists.

DOE Office of Scientific and Technical Information (OSTI.GOV)

bedle, H; Matzel, E; Flanagan, M

This report summarizes the data analysis achieved during Heather Bedle's eleven-week Technical Scholar internship at Lawrence Livermore National Labs during the early summer 2006. The work completed during this internship resulted in constraints on the crustal and upper mantle S-velocity structure in Northern Africa, the Mediterranean, the Middle East, and Europe, through the fitting of regional waveform data. This data extends current raypath coverage and will be included in a joint inversion along with data from surface wave group velocity measurements, S and P teleseismic arrival time data, and receiver function data to create an improved velocity model of themore » upper mantle in this region. The tectonic structure of the North African/Mediterranean/Europe/Middle Eastern study region is extremely heterogeneous. This region consists of, among others, stable cratons and platforms such as the West Africa Craton, and Baltica in Northern Europe; oceanic subduction zones throughout the Mediterranean Sea where the African and Eurasian plate collide; regions of continental collision as the Arabian Plate moves northward into the Turkish Plate; and rifting in the Red Sea, separating the Arabian and Nubian shields. With such diverse tectonic structures, many of the waveforms were difficult to fit. This is not unexpected as the waveforms are fit using an averaged structure. In many cases the raypaths encounter several tectonic features, complicating the waveform, and making it hard for the software to converge on a 1D average structure. Overall, the quality of the waveform data was average, with roughly 30% of the waveforms being discarded due to excessive noise that interfered with the frequency ranges of interest. An inversion for the 3D S-velocity structure of this region was also performed following the methodology of Partitioned Waveform Inversion (Nolet, 1990; Van der Lee and Nolet, 1997). The addition of the newly fit waveforms drastically extends the range of the model. The model now extends as far east in Africa to cover Chad and Niger, and reaches south to cover Zambia. The model is also stretched eastward to cover the eastern half of India, and northward to cover the southern portion of Scandinavia.« less

The Tell-Rif belt in the geodynamic frame of the West Mediterranean

NASA Astrophysics Data System (ADS)

Leprêtre, Rémi; Frizon de Lamotte, Dominique; Combier, Violaine; Gorini, Christian; Eschard, Remi

2017-04-01

The Tell-Rif (Tell in Algeria and Tunisia; Rif in Morocco) or Maghrebides is the orogenic system fringing the West Mediterranean basins to the south. This system comprises 3 major tectonic-paleogeographic zones from north to south: (1) the internal zones (AlKaPeCa for Alboran, Kabylies, Peloritan, Calabria) originated from the former northern European margin of the Maghrebian Tethys (MT); (2) the "flyschs zone" regarded as the former sedimentary cover of the MT and (3) the external zones, the former southern African passive margin of the MT. In the geodynamic frame of the West Mediterranean basins formation, the Tell-Rif is interpreted as the direct result of the progressive closure of the MT until the collision between AlKaPeCa and Africa at 17 Ma and the propagation of the deformation within Africa. Such a scenario gives a consistent explanation for the off-shore geodynamics and is now shared by almost all the authors. Nevertheless, all the geodynamic models do not integrate recent developments regarding the geology the Tell-Rif. In particular, the following points must be integrated in any models: (1) The importance of pre-Late Oligocene (pre-30 Ma) contractional events not only in the Atlas System, where they are well established, but also in the Tell-Rif system, where their effects are often ignored or minimized; (2) The existence of MP-BT metamorphic rocks associated with fragments of ophiolites in the Eastern External Rif and likely in the Western External Tell suggesting that the southern Maghrebian Tethys margin is more complicated than what could be expected for a single linear oceanic domain; (3) The presence over the Rif and western Tell of wide Miocene basins developed along with the ones of the West Mediterranean Basins. Among these basins, the Cheliff Basin occupies a large part of the western Tell in Algeria. These elements must be taken into account for a reassessment of the complex relationships between the West Mediterranean Basins and the surrounding mountain belts. Integration of these major issues allows us to re-evaluate the configuration of the African margin before the inversion and to propose a kinematic scenario for the Tell-Rif.

Cyclotron-based of plant gravisensing

NASA Astrophysics Data System (ADS)

Kordyum, E.; Kalinina, Ia.; Bogatina, N.; Kondrachuk, A.

Roots exhibit positive gravitropism they grow in the direction of a gravitational vector while shoots respond negatively and grow opposite to a gravitational vector We first demonstrated the inversion of roots gravitropism from positive to negative one under gravistimulation in the weak combined magnetic field WCMF consisted of permanent magnetic field PMF with the magnitude of order of 50 mu T and altering magnetic field AMF with the 6 mu T magnitude and a frequency of 32 Hz It was found that the effect of inversion has a resonance nature It means that in the interval of frequencies 1-45 Hz inversion of root gravitropism occurs only at frequency 32 Hz 2-3-day old cress seedlings were gravistimulated in moist chambers which are placed in mu -metal shields Inside mu -metal shields combined magnetic fields have been created The magnitude of magnetic fields was measured by a flux-gate magnetometer Experiments were performed in darkness at temperature 20 pm 1 0 C We measured the divergence angle of a growing root from its horizontal position After 1 h of gravistimulation in the WCMF we observed negative gravitropism of cress roots i e they grow in the opposite direction to a gravitational vector Frequency of 32 Hz for the magnitude of the PMF applied formally corresponds to cyclotron frequency of Ca 2 ions This indicates possible participation of calcium ions in root gravitropism There are many evidences of resonance effects of the WCMF on the biological processes that involve Ca 2 but the nature of

[Compounds modulating parathyroid hormone (PTH) secretion].

PubMed

Nagano, N; Iijima, H

2001-08-01

The control of parathyroid hormone (PTH) secretion is strictly regulated by the parathyroid Ca receptor (CaR). Calcimimetics and calcilytics selectively act on the parathyroid CaR to inhibit and enhance PTH secretion, respectively. According to the recent pharmacological two-state model, calcimimetics act on the CaR as allosteric agonists to stabilize an active conformation of CaR. Conversely, calcilytics act on the CaR as allosteric inverse agonists to stabilize an inactive conformation of CaR. These compounds that can alter circulating levels of PTH and bone turnover might provide novel treatments for adynamic bone disease in patients with chronic renal failure.

Charge renormalization and inversion of a highly charged lipid bilayer: effects of dielectric discontinuities and charge correlations.

PubMed

Taheri-Araghi, Sattar; Ha, Bae-Yeun

2005-08-01

We reexamine the problem of charge renormalization and inversion of a highly charged surface of a low dielectric constant immersed in ionic solutions. To be specific, we consider an asymmetrically charged lipid bilayer, in which only one layer is negatively charged. In particular, we study how dielectric discontinuities and charge correlations (among lipid charges and condensed counterions) influence the effective charge of the surface. When counterions are monovalent (e.g., Na+), our mean-field approach implies that dielectric discontinuities can enhance counterion condensation. A simple scaling picture shows how the effects of dielectric discontinuities and surface-charge distributions are intertwined: Dielectric discontinuities diminish condensation if the backbone charge is uniformly smeared out while counterions are localized in space; they can, however, enhance condensation when the backbone charge is discrete. In the presence of asymmetric salts such as CaCl2 , we find that the correlation effect, treated at the Gaussian level, is more pronounced when the surface has a lower dielectric constant, inverting the sign of the charge at a smaller value of Ca2+ concentration.

3-D crustal structure beneath the southern Korean Peninsula from local earthquakes

NASA Astrophysics Data System (ADS)

Kim, K. H.; Park, J. H.; Park, Y.; Hao, T.; Kang, S. Y.; Kim, H. J.

2017-12-01

Located at the eastern margin of the Eurasian continent, the geology and tectonic evolution of the Korean Peninsula are closely related to the rest of the Asian continent. Although the widespread deformation of eastern Asia and its relation to the geology and tectonics of the Korean Peninsula have been extensively studied, the answers to many fundamental questions about the peninsula's history remain inconclusive. The three-dimensional subsurface structure beneath the southern Korean Peninsula is poorly known, even though such information could be key in verifying or rejecting several competing models of the tectonic evolution of East Asia. We constructed a three-dimensional velocity model of the upper crust beneath the southern Korean Peninsula using 19,935 P-wave arrivals from 747 earthquakes recorded by high-density local seismic networks maintained by Korea Meteorological Administration and Korea Institute of Geosciences and Mineral Resources. Results show significant lateral and vertical variations: velocity increases from northwest to southeast at shallow depths, and significant velocity variations are observed across the South Korea Tectonic Line between the Okcheon Fold Belt and the Youngnam Massif. Collision between the North China and South China blocks during the Early Cretaceous might have caused extensive deformation and the observed negative velocity anomalies in the region. The results of the tomographic inversion, combined with the findings of previous studies of Bouguer and isostatic gravity anomalies, indicate the presence of high-density material in the upper and middle crust beneath the Gyeongsang Basin in the southeastern Korean Peninsula. Although our results partially support the indentation tectonic model, it is still premature to discard other tectonic evolution models because our study only covers the southern half of the peninsula.

Multiple, discrete inversion episodes revealed by apatite fission track analysis along the southernmost Atlantic margin of South Africa

NASA Astrophysics Data System (ADS)

Wildman, M.; Brown, R. W.; Persano, C.; Stuart, F. M.

2013-12-01

The morpho-tectonic history of the western South African continental margin and interior plateau remains enigmatic. Recent investigations of offshore sediment accumulation and interpretations of onshore structural and geomorphological observations have highlighted the complex geological evolution of South Africa throughout the Mesozoic and Cenozoic. Moreover, advances in geodynamic modelling approaches have explored the crustal response to varying styles of rifting and the influence of mantle upwelling beneath the African plate. These geological observations and models, however, require validation from quantitative constraints on the surface response (i.e. uplift and erosion) to syn- and post rift thermal and tectonic processes Over the last two decades, low temperature thermochronometry, particularly apatite fission track analysis (AFTA) and apatite (U-Th)/He, have been effective tools in providing these constraints by tracking the time-temperature history of rocks through c. 60 - 110°C and 80 - 40°C, respectively. The unique ability of AFTA to constrain both the timing and nature of sample cooling rests largely on the sensitivity of fission track annealing to temperature. Here, we present new AFT data from a suite of samples across the entire western continental margin of South Africa which contributes to a now extensive AFT dataset spanning the entire sub-continent. This dataset broadly invokes at least two discrete episodes of cooling driven by km scale denudation at c. 130 Ma, following rifting and break up of West Gondwana, and 90 Ma as a response to renewed tectonic uplift. However, the apparent lack of correlation of AFT age with elevation or with distance from the coast highlight the spatial and temporal variability of post-rift cooling that may be related to Mid-Cretaceous structural reactivation along the margin. We also present thermal history modelling using the Bayesian transdimensional inverse modelling approach of QTQt (Gallagher, 2012). Modelling was performed for several outcrop samples, including a 604 m vertical profile, and two borehole profiles from the interior plateau with bottom depths of 2.5 (QU 1/65) and 6.2 km (KC 1/70). The results of this novel modelling approach are interpreted alongside independent on and offshore geological observations to lend additional support to the occurrence of multiple, discrete episodes of denudation driven cooling at c. 150 - 130 and 90 Ma, and possibly a later Cretaceous episode of cooling at c. 70 Ma. The existence of a Late Cretaceous or younger period of enhanced denudation is being further explored through ongoing work combining new AFT data with apatite (U-Th)/He data to generate more robust thermal history information and provide new insights into the timing and magnitude of the major periods of uplift and erosion that have formed the first order topography of South Africa. Gallagher, K., 2012, Transdimensional inverse thermal history modeling for quantitative thermochronology: Journal of Geophysical Research: Solid Earth, v. 117(B2).

Automated Carrier Landing of an Unmanned Combat Aerial Vehicle Using Dynamic Inversion

DTIC Science & Technology

2007-06-01

17 CN normal force coefficient . . . . . . . . . . . . . . . . . . . . 17 CA axial force coefficient...slug·ft2 Ixzb 0 slug·ft2 The aircraft has a single engine inlet for a single, centerline mounted turbofan engine. For purposes of this research, the...assumed to remain constant for each simulation run and were based on an assumed 10% fuel load with full weapons [2]. The rest of these values were

Crystal structures of Ca(ClO4)2·4H2O and Ca(ClO4)2·6H2O

PubMed Central

Hennings, Erik; Schmidt, Horst; Voigt, Wolfgang

2014-01-01

The title compounds, calcium perchlorate tetra­hydrate and calcium perchlorate hexa­hydrate, were crystallized at low temperatures according to the solid–liquid phase diagram. The structure of the tetra­hydrate consists of one Ca2+ cation eightfold coordinated in a square-anti­prismatic fashion by four water mol­ecules and four O atoms of four perchlorate tetra­hedra, forming chains parallel to [01-1] by sharing corners of the ClO4 tetra­hedra. The structure of the hexa­hydrate contains two different Ca2+ cations, each coordinated by six water mol­ecules and two O atoms of two perchlorate tetra­hedra, forming [Ca(H2O)6(ClO4)]2 dimers by sharing two ClO4 tetra­hedra. The dimers are arranged in sheets parallel (001) and alternate with layers of non-coordinating ClO4 tetra­hedra. O—H⋯O hydrogen bonds between the water mol­ecules as donor and ClO4 tetra­hedra and water mol­ecules as acceptor groups lead to the formation of a three-dimensional network in the two structures. Ca(ClO4)2·6H2O was refined as a two-component inversion twin, with an approximate twin component ratio of 1:1 in each of the two structures. PMID:25552974

Petrogenesis of the granitic Donkerhuk batholith in the Damara Belt of Namibia: protracted, syntectonic, short-range, crustal magma transfer

NASA Astrophysics Data System (ADS)

Clemens, J. D.; Buick, I. S.; Kisters, A. F. M.; Frei, D.

2017-07-01

The areally extensive (>5000 km2), syn-tectonic, ca. 520 Ma, mainly S-type Donkerhuk batholith was constructed through injection of thousands of mainly sheet-like magma pulses over 20-25 Myr. It intruded schists of the Southern Zone accretionary prism in the Damara Belt of Namibia. Each magma pulse had at least partly crystallised prior to the arrival of the following batch. However, much of the batholith may have remained partially molten for long periods, close to the H2O-saturated granite solidus. The batholith shows extreme variation in chemistry, while having limited mineralogical variation, and seems to be the world's most heterogeneous granitic mass. The Nd model ages of 2 Ga suggest that Eburnean rocks of the former magmatic arc, structurally overlain by the accretionary wedge, are the most probable magma sources. Crustal melting was initiated by mantle heat flux, probably introduced by thermal diffusion rather than magma advection. The granitic magmas were transferred from source to sink, with minimal intermediate storage; the whole process having occurred in the middle crust, resulting in feeble crustal differentiation despite the huge volume of silicic magma generated. Source heterogeneity controlled variation in the magmas and neither mixing nor fractionation was prominent. However, due to the transpressional emplacement régime, local filter pressing formed highly silicic liquids, as well as felsic cumulate rocks. The case of the Donkerhuk batholith demonstrates that emplacement-level tectonics can significantly influence compositional evolution of very large syn-tectonic magma bodies.

Lithosphere deformation methods and models constrained by surface fault data on Mars

NASA Astrophysics Data System (ADS)

Dimitrova, Lada L.

Models of lithospheric deformation tie observed field measurements of gravity and topography with surface observations of tectonic features. An understanding of the sources of stress, and the expected style, orientation, and magnitudes of stress and associated elastic strain is important for understanding the evolution of faulting on Mars and its relationship to loading. At the same time, theoretical models of deformation mechanisms and forces, when tied to tectonic observations, can be interpreted in terms of major tectonic events and allow insights into the planet's history and evolution as well as its internal structure and processes. This is particularly important for understanding solid planetary bodies other than Earth where the seismic data is either sparse, e.g. the Moon, or non-existent, e.g. Mars. This kind of research has implications for, and benefits from, an understanding of the petrology and surface processes. In this work, I use MGS MOLA and Radio Science data products (topography and gravity) to systematically test new geodynamic models and evaluate lithosphere dynamics on Mars as a function of time, while satisfying geologic surface observations (surface features) that have been and are being catalogued and studied from Viking, MOLA, MOC, and THEMIS IR images. I investigate (1) the role of internal loads (internal body force effects), (2) loading from the surface and base of lithosphere, and the effects of this loading on membrane and flexural strains and stresses, and (3) the role of global contraction, all viewed in the context of how the surface elastic layer has changed as the planet has evolved. I show that deviatoric stresses associated with gravitational potential differences do a good job at matching the normal faults; however, fitting all the surface-breaking faults is more difficult. I argue that global planetary contraction is an unlikely source of significant deformation. Instead, the simplest inverse models show that small lateral variations (1¡6%) in crust and mantle density in conjunction with small vertical displacement, O(100m), provide sufficient additional GPE and membrane stress to fit the majority of the data. These inverse models are consistent with lithosphere modification by erosion from running water.

Exhumation of the Deylaman fault trend and its effects on the deformation style of the western Alborz belt in Iran

NASA Astrophysics Data System (ADS)

Hakimi Asiabar, Saeid; Bagheriyan, Siyamak

2018-03-01

The Alborz range in northern Iran stretches along the southern coast of the Caspian Sea and finally runs northeast and merges into the Pamir mountains in Afghanistan. Alborz mountain belt is a doubly vergent orogen formed along the northern edge of the Iranian plateau in response to the closure of the Neo-Tethys ocean and continental collision between Arabia and Eurasia. The south Caspian depression—the Alborz basin of Mesozoic age (with W-E trend) in northern Iran—inverted in response to the Arabia-Eurasia collision. Pre-existing extensional faults of the south Caspian-Alborz system preferentially reactivated as contractional faults because of tectonic inversion. These contractional structures tend to run parallel to the trends of pre-existing extensional faults and acquire W and WNW-ESE orientations across the previous accommodation zones that were imposed by the reactivation of adjacent extensional faults with different directions. The NNE to N dipping faults show evidences of reactivation. The Deylaman fault is one of the important faults of western Alborz in Iran and is an example of inversion tectonic style of deformation in the western Alborz mountain range. The Deylaman fault, with an E-W trend, contains three discontinuous fault segments in the area under investigation. These fault segments have evidence of oblique right-lateral reverse motion and links eastward to the dextral Kandavan thrust. The importance of this fault is due to its effect on sedimentation of several rock units from the Jurassic to Neogene in western Alborz; the rock facies on each side of this fault are very different and illustrate different parts of tectonic history.

Complex brittle deformation pattern along the Southern Patagonian Andes (Argentina)

NASA Astrophysics Data System (ADS)

Barberón, Vanesa; Sue, Christian; Ronda, Gonzalo; Ghiglione, Matías

2016-04-01

The Southern Patagonian Andes is located in the southern extreme of the Pacific subduction zone, where the Antartic oceanic plate sinks underneath South America. The history of the area begins with compression during Paleozoic, Jurassic extension associated to the rift and opening of the South Atlantic Ocean, then a sag stage in the Lower Cretaceous followed by a foreland phase as a result of plate tectonics (Ghiglione et al., 2016). The kinematic study is concentrated in the Argentinean foothills, between 46°40' and 48° SL. We measured around 800 fault planes and their striaes with the sense of movement in order to characterize the stress field. The software used to make the stress inversion were Tensor (Delvaux, 2011) and Multiple Inverse Method MIM (Yamaji et al., 2011). The stress field map was built with the results of the MIM. We present new data from 48 sites located in the northern sector of the Southern Patagonian Andes. The measurements were made in several rocks from Paleozoic to Lower Cretaceous, even though most were taken in pyroclastic jurassic rocks from El Quemado Complex. Paleostress tensors obtained are mostly strike-slip, although a 25% is normal and there are a few compresional. The pattern of faults found is complex. In some sites the tensor can be locally linked to satellite images and observations from the field or be related to a major thrust front. There is no clear correlation between the age and/or lithology with the tensor since the youngest rocks measured are Lower Cretaceous. Probably there are several generations of family faults connected to different and recent tectonic phases then the paleostress tensors might correspond to the latest tectonic events.

Inversion of the Erlian Basin (NE China) in the early Late Cretaceous: Implications for the collision of the Okhotomorsk Block with East Asia

NASA Astrophysics Data System (ADS)

Guo, Zhi-Xin; Shi, Yuan-Peng; Yang, Yong-Tai; Jiang, Shuan-Qi; Li, Lin-Bo; Zhao, Zhi-Gang

2018-04-01

A significant transition in tectonic regime from extension to compression occurred throughout East Asia during the mid-Cretaceous and has stimulated much attention. However, the timing and driving mechanisms of the transition remain disputed. The Erlian Basin, a giant late Mesozoic intracontinental petroliferous basin located in the Inner Mongolia, Northeast China, contains important sedimentary and structural records related to the mid-Cretaceous compressional event. The stratigraphical, sedimentological and structural analyses reveal that a NW-SE compressional inversion occurred in the Erlian Basin between the depositions of the Lower Cretaceous Saihan and Upper Cretaceous Erlian formations, causing intense folding of the Saihan Formation and underlying strata, and the northwestward migration of the depocenters of the Erlian Formation. Based on the newly obtained detrital zircon U-Pb data and previously published paleomagnetism- and fossil-based ages, the Saihan and Erlian formations are suggested as latest Aptian-Albian and post-early Cenomanian in age, respectively, implying that the inversion in the Erlian Basin occurred in the early Late Cretaceous (Cenomanian time). Apatite fission-track thermochronological data record an early Late Cretaceous cooling/exhuming event in the basin, corresponding well with the aforementioned sedimentary, structural and chronological analyses. Combining with the tectono-sedimentary evolutions of the neighboring basins of the Erlian Basin, we suggest that the early Late Cretaceous inversional event in the Erlian Basin and the large scale tectonic transition in East Asia shared the common driving mechanism, probably resulting from the Okhotomorsk Block-East Asia collisional event at about 100-89 Ma.

U-Pb Geochronology and Hf-isotope constrains on Formation of Archaean Crust From the Lewisian of NW Scotland, Great Britain

NASA Astrophysics Data System (ADS)

Crowley, Q. G.; Noble, S. R.; Key, R.

2006-12-01

The Lewisian complex of NW Scotland is dominantly composed of Archaean tonalitic to granodioritic gneisses, ultramafic bodies and minor metasedimentary components. Although the area is internationally well known and has been much studied for over a century, the precise timing of crustal forming events has proven difficult to ascertain. We present data from both in-situ laser ablation (LA) ICP-MS and an adaptation of a new U-Pb chemical abrasion ID-TIMS technique (Mattinson 2006) applied to multi-age component zircons from the Assynt block of this region. The new data reveal a previously unrecognised complexity and provide the first unequivocal proof of an Archean metamorphic event in the area. In a wider context the data also elucidate some of the processes involved in early global crust formation and plate tectonic events. In-situ LA-ICPMS U-Pb dating has indicated a ca 2.8Ga protolith age for a tonalite gneiss with evidence for a ca. 3.6Ga xenocrystic component (the oldest discovered in the UK). Non-conventional U-Pb ID-TIMS utilising a combination of high-temperature annealing followed by multi-step incremental dissolution on single grains has dated zircon growth at ca 2.7Ga (Badcallian) and 2.5Ga (Inverian) with later Pb-loss occurring at ca 1.9Ga and ca 1.7Ga (early and late Laxfordian respectively). This latter method combines a pseudo-spatial resolution normally associated with an in-situ technique but benefits from the high-precision analysis of ID-TIMS. Zircon Hf isotopes indicate that some rocks from the Assynt area are typical of Archaean continental crust (epsilon Hf ca -1. The tonalite gneisses however have strongly negative epsilon Hf values of -7 to -10 indicating a more complex history of derivation through partial melting of ancient crust with residual garnet as a long- lived control on Hf. Archaean events at ca. 3.6Ga, ca 2.8Ga and ca 2.7Ga have also been recorded in west Greenland (e.g. Mojzsis & Harrison 1999, Richards and Appel, 1987, Whitehouse et al 1999). This points towards widespread and important crustal forming events. Locally in Assynt in the Lewisian of NW Scotland these events are recorded with zircon crystallisation from a magma at ca 3.6Ga, partial melting and crustal recycling producing the tonalite gneiss protoliths at ca 2.8Ga, a prolonged lower crustal residence in granulite P-T conditions by ca 2.7Ga, further metamorphism in amphibolite conditions at ca 2.5Ga and later deformation associated with punctuated terrane amalgamation events between ca 1.9Ga and ca 1.7Ga.

Timing of tectonic evolution of the East Kunlun Orogen, Northern Tibet Plateau

NASA Astrophysics Data System (ADS)

Dong, Yunpeng

2017-04-01

The East Kunlun Orogen, located at the northern Tibet Plateau, represents the western segment of the Central China Orogenic Belt which was formed by amalgamation of the North China blocks and South China blocks. It is a key to understanding the formation of Eastern Asian continent as well as the evolution of the Pangea supercontinent. Based on detailed geological mapping, geochemical and geochronological investigations, the orogen is divided into three main tectonic belts, from north to south, including the Northern Qimantagh, Central Kunlun and Southern Kunlun Belts by the Qimantagh suture, Central Kunlun suture and South Kunlun fault. The Qimantagh suture is marked by the Early Paleozoic ophiolites outcropped in the Yangziquan, Wutumeiren, and Tatuo areas, which consist mainly of peridotites, gabbros, diabases and basalts. Besides, the ophiolite in the Wutumeiren is characterized by occurring anorthosite while the ophiolite in the Tatuo occurring chert. The basalts and diabases from both Yaziquan and Tatuo areas display depletion of Nb, Ta, P and Ti, and enrichment of LILE, suggesting a subduction related tectonic setting. LA-ICP-MS zircon U-Pb age of 421 Ma for the diabase represents the formation age of the Yaziquan ophiolite, while the U-Pb ages of 490 Ma and 505 Ma for gabbro and anorthosite, respectively, constrain the formation age of the Tatuo ophiolite. The basaltic rocks in the Wutumeiren area display flat distribution of HFSEs (such as Nb, Ta, K, La, Ce, Pr, Nd, Zr, Sm, Eu, Ti, Dy, Y, Yb and Lu) and slightly enrichment in LREEs, while the peridotites showing depletion in MREEs. The LA-ICP-MS zircon U-Pb age of 431 Ma for the gabbro represents the formation age of the Wutumeiren ophiolite. Together with regional geology, we suggest herewith a back-arc basin tectonic setting during ca. 505-421 Ma at least for the Qimantagh suture. The Central Kunlun suture is represented by the ophiolite in the Wutuo area, which is characterized by depletion of Nb, Ta, P and Ti, and enrichment of LILEs, LREEs, K, Pb, Sr and Nd, accounting for a subduction relation setting. The gabbro yields a LA-ICP-MS zircon U-Pb age of 243 Ma, representing the formation age of the ophiolite. Taking into account of evidence from the Early Paleozoic ophiolites in the Buqinshan ( Bian Qiantao et al., 2001, 2007; Li Zuochen et al., 2013; Li Ruibao et al., 2014; Liu Zhanqing et al., 2011) and the Derni areas (Chen Liang et al., 2001, 2003), the Central Kunlun ocean might be existed from Early Paleozoic to Middle Triassic time. The Northern Qimantagh tectonic belt, to the north of the Qimantagh suture, exposes a large volume of Early Paleozoic granitic plutons and volcanic rocks. Geochemistry of the granites suggests an arc setting. LA-ICP-MS zircon U-Pb ages ranging from ca. 440 to 402 Ma constrain the time of the subduction and arc setting. The Central Kunlun tectonic belt is characterized by occurring of Paleo-Proterozoic basement which was intruded by large amounts of Triassic granitoids. The basement represented by the Jinshuikou Group including gneisses, amphibolites and marbles, yields a protolith formation age of 2.2 Ga which was overprinted by Neoproterozoic tectono-thermal event. The plutonic intrusions display LA-ICP-MS zircon ages mainly of 260-200 Ma with minor ages of 470-400 Ma, revealing a long-lived subduction from Early Paleozoic to Late Triassic. Taken into together all above evidence, trench-arc-back arc basin tectonics were suggested here accounting for the tectonic evolution of the East Kunlun Orogeny during Early Paleozoic to Triassic time.

Euro-African MAGSAT anomaly-tectonic observations

NASA Technical Reports Server (NTRS)

Hinze, W. J.; Olivier, R.; Vonfrese, R. R. B.

1985-01-01

Preliminary satellite (MAGSAT) scalar magnetic anomaly data are compiled and differentially reduced to radial polarization by equivalent point source inversion for comparison with tectonic data of Africa, Europe and adjacent marine areas. A number of associations are evident to constrain analyses of the tectonic features and history of the region. The Precambrian shields of Africa and Europe exhibit varied magnetic signatures. All shields are not magnetic highs and, in fact, the Baltic shield is a marked minimum. The reduced-to-the-pole magnetic map shows a marked tendency for northeasterly striking anomalies in the eastern Atlantic and adjacent Africa, which is coincident to the track of several hot spots for the past 100 million years. However, there is little consistency in the sign of the magnetic anomalies and the track of the hot spots. Comparison of the radially polarized anomalies of Africa and Europe with other reduced-to-the-pole magnetic satellite anomaly maps of the Western Hemisphere support the reconstruction of the continents prior to the origin of the present-day Atlantic Ocean in the Mesozoic Era.

Euro-african MAGSAT Anomaly-tectonic Observations

NASA Technical Reports Server (NTRS)

Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator); Olivier, R.

1984-01-01

Preliminary satellite (MAGSAT) scalar magnetic anomaly data are compiled and differentially reduced to radial polarization by equivalent point source inversion for comparison with tectonic data of Africa, Europe and adjacent marine areas. A number of associations are evident to constrain analyses of the tectonic features and history of the region. The Precambrian shields of Africa and Europe exhibit varied magnetic signatures. All shields are not magnetic highs and, in fact, the Baltic shield is a marked minimum. The reduced-to-the-pole magnetic map shows a marked tendency for northeasterly striking anomalies in the eastern Atlantic and adjacent Africa, which is coincident to the track of several hot spots for the past 100 million years. However, there is little consistency in the sign of the magnetic anomalies and the track of the hot spots. Comparison of the radially polarized anomalies of Africa and Europe with other reduced-to-the-pole magnetic satellite anomaly maps of the Western Hemisphere support the reconstruction of the continents prior to the origin of the present-day Atlantic Ocean in the Mesozoic Era.

Tensor Invariant Processing for Munitions/Clutter Classification

DTIC Science & Technology

2013-11-01

Report," U.S. Naval Research Laboratory Report NRL/MR/ 6110 --12-9401, April 2012. 5. ESTCP Live Site Demonstrations, Former Camp Beale, Marysville, CA ...currently valid OMB control number. 1. REPORT DATE NOV 2013 2 . REPORT TYPE 3. DATES COVERED 00-00-2013 to 00-00-2013 4. TITLE AND SUBTITLE...inversion............................................................. 4 Figure 2 . Multi-coil arrays exciting target with different primary field directions

Unravelling how βCaMKII controls the direction of plasticity at parallel fibre-Purkinje cell synapses

NASA Astrophysics Data System (ADS)

Pinto, Thiago M.; Schilstra, Maria J.; Steuber, Volker; Roque, Antonio C.

2015-12-01

Long-term plasticity at parallel fibre (PF)-Purkinje cell (PC) synapses is thought to mediate cerebellar motor learning. It is known that calcium-calmodulin dependent protein kinase II (CaMKII) is essential for plasticity in the cerebellum. Recently, Van Woerden et al. demonstrated that the β isoform of CaMKII regulates the bidirectional inversion of PF-PC plasticity. Because the cellular events that underlie these experimental findings are still poorly understood, our work aims at unravelling how β CaMKII controls the direction of plasticity at PF-PC synapses. We developed a bidirectional plasticity model that replicates the experimental observations by Van Woerden et al. Simulation results obtained from this model indicate the mechanisms that underlie the bidirectional inversion of cerebellar plasticity. As suggested by Van Woerden et al., the filamentous actin binding enables β CaMKII to regulate the bidirectional plasticity at PF-PC synapses. Our model suggests that the reversal of long-term plasticity in PCs is based on a combination of mechanisms that occur at different calcium concentrations.

Electronic structure of Mott-insulator CaCu3Ti4O12: Photoemission and inverse photoemission study

NASA Astrophysics Data System (ADS)

Im, H. J.; Iwataki, M.; Yamazaki, S.; Usui, T.; Adachi, S.; Tsunekawa, M.; Watanabe, T.; Takegahara, K.; Kimura, S.; Matsunami, M.; Sato, H.; Namatame, H.; Taniguchi, M.

2015-09-01

We have performed the photoemission and inverse photoemission experiments to elucidate the origin of Mott insulating states in A-site ordered perovskite CaCu3Ti4O12 (CCTO). Experimental results have revealed that Cu 3d-O 2p hybridized bands, which are located around the Fermi level in the prediction of the local-density approximation (LDA) band calculations, are actually separated into the upper Hubbard band at ~1.5 eV and the lower Hubbard band at ~-1.7 eV with a band gap of ~1.5-1.8 eV. We also observed that Cu 3d peak at ~-3.8 eV and Ti 3d peak at ~3.8 eV are further away from each other than as indicated in the LDA calculations. In addition, it is found that the multiplet structure around -9 eV includes a considerable number of O 2p states. These observations indicate that the Cu 3d and Ti 3d electrons hybridized with the O 2p states are strongly correlated, which originates in the Mott-insulating states of CCTO.

Accurate estimation of seismic source parameters of induced seismicity by a combined approach of generalized inversion and genetic algorithm: Application to The Geysers geothermal area, California

NASA Astrophysics Data System (ADS)

Picozzi, M.; Oth, A.; Parolai, S.; Bindi, D.; De Landro, G.; Amoroso, O.

2017-05-01

The accurate determination of stress drop, seismic efficiency, and how source parameters scale with earthquake size is an important issue for seismic hazard assessment of induced seismicity. We propose an improved nonparametric, data-driven strategy suitable for monitoring induced seismicity, which combines the generalized inversion technique together with genetic algorithms. In the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for attenuation and site contributions. Then, the retrieved source spectra are inverted by a nonlinear sensitivity-driven inversion scheme that allows accurate estimation of source parameters. We therefore investigate the earthquake source characteristics of 633 induced earthquakes (Mw 2-3.8) recorded at The Geysers geothermal field (California) by a dense seismic network (i.e., 32 stations, more than 17.000 velocity records). We find a nonself-similar behavior, empirical source spectra that require an ωγ source model with γ > 2 to be well fit and small radiation efficiency ηSW. All these findings suggest different dynamic rupture processes for smaller and larger earthquakes and that the proportion of high-frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with earthquake size. Furthermore, we observe also two distinct families of events with peculiar source parameters that in one case suggests the reactivation of deep structures linked to the regional tectonics, while in the other supports the idea of an important role of steeply dipping faults in the fluid pressure diffusion.

Progressive magmatism and evolution of the Variscan suture in southern Iberia

NASA Astrophysics Data System (ADS)

Braid, James A.; Murphy, J. Brendan; Quesada, Cecilio; Gladney, Evan R.; Dupuis, Nicolle

2018-04-01

Magmatic activity is an integral component of orogenic processes, from arc magmatism during convergence to post-collisional crustal melting. Southern Iberia exposes a Late Paleozoic suture zone within Pangea and where a crustal fragment of Laurussia (South Portuguese Zone) is juxtaposed with parautochthonous Gondwana (Ossa Morena Zone). Fault-bounded oceanic metasedimentary rocks, mélanges and ophiolite complexes characterize the suture zone and are intruded by plutonic rocks and mafic dykes. The generation and emplacement of these intrusive rocks and their relationship to development of the suture zone and the orogen are undetermined. Field evidence combined with U/Pb (zircon) geochronology reveals three main phases of plutonism, a pre-collisional unfoliated gabbroic phase emplaced at ca 354 Ma, crosscut by a syn-tectonic ca 345 Ma foliated granodiorite phase followed by a ca 335 Ma granitic phase. Geochemical analyses (major, trace, rare earth elements) indicate that the gabbro exhibits a calc-alkaline arc signature whereas the granodiorite and granite are typical of post-collisional slab break-off. Taken together, these data demonstrate a protracted development of the orogen and support a complex late stage evolution broadly similar to the tectonics of the modern eastern Mediterranean. In this scenario, the highly oblique closure of a small tract of oceanic lithosphere postdates the main collision event resulting in escape of parautochthonous and allochthonous terranes toward the re-entrant.

Dietary calcium intake is associated with adiposity, metabolic profile, inflammatory state and blood pressure, but not with erythrocyte intracellular calcium and endothelial function in healthy pre-menopausal women.

PubMed

da Silva Ferreira, Thaís; Torres, Márcia Regina Simas Gonçalves; Sanjuliani, Antonio Felipe

2013-09-28

Recent studies have suggested that dietary Ca may have beneficial effects on adiposity, insulin resistance, dyslipidaemia and blood pressure (BP). One potential mechanism underlying these benefits involves modifications in intracellular Ca concentration ([Ca2+]i). The present study aimed to evaluate the associations of dietary Ca with adiposity, erythrocyte [Ca2+]i, metabolic profile, BP, inflammatory state and endothelial function in healthy pre-menopausal women. In the present cross-sectional study, seventy-six women aged 18–50 years were submitted to the evaluation of dietary intake, anthropometric parameters, body composition, erythrocyte [Ca2+]i, biochemical variables, endothelial function and BP. A FFQ was used to assess usual dietary intake. Endothelial function was evaluated by serum concentrations of adhesion molecules and by the peripheral arterial tonometry (PAT) method, using Endo-PAT 2000®. Participants were allocated into two groups according to Ca intake: low-Ca group (LCG; n 32; < 600 mg/d) and high-Ca group (HCG; n 44; ≥ 600 mg/d). Women in the LCG compared with those in the HCG exhibited, after adjustments for potential confounders, higher values of BMI, waist circumference, waist:height ratio, percentage of body fat, insulin, homeostasis model assessment of insulin resistance, leptin, diastolic and mean BP; and lower levels of HDL-cholesterol, adiponectin and vascular cell adhesion molecule 1. Endothelial function assessed by PAT and [Ca2+]i was similar in both groups. Subjects in the HCG had lower OR for prevalent overweight, obesity, abdominal obesity, insulin resistance, HDL-cholesterol < 600 mg/l and systolic BP >120 mmHg. The findings of the present study suggest that high Ca intake is inversely associated with some cardiovascular risk factors.

2D Inviscid and Viscous Inverse Design Using Continuous Adjoint and Lax-Wendroff Formulation

NASA Astrophysics Data System (ADS)

Proctor, Camron Lisle

The continuous adjoint (CA) technique for optimization and/or inverse-design of aerodynamic components has seen nearly 30 years of documented success in academia. The benefits of using CA versus a direct sensitivity analysis are shown repeatedly in the literature. However, the use of CA in industry is relatively unheard-of. The sparseness of industry contributions to the field may be attributed to the tediousness of the derivation and/or to the difficulties in implementation due to the lack of well-documented adjoint numerical methods. The focus of this work has been to thoroughly document the techniques required to build a two-dimensional CA inverse-design tool. To this end, this work begins with a short background on computational fluid dynamics (CFD) and the use of optimization tools in conjunction with CFD tools to solve aerodynamic optimization problems. A thorough derivation of the continuous adjoint equations and the accompanying gradient calculations for inviscid and viscous constraining equations follows the introduction. Next, the numerical techniques used for solving the partial differential equations (PDEs) governing the flow equations and the adjoint equations are described. Numerical techniques for the supplementary equations are discussed briefly. Subsequently, a verification of the efficacy of the inverse design tool, for the inviscid adjoint equations as well as possible numerical implementation pitfalls are discussed. The NACA0012 airfoil is used as an initial airfoil and surface pressure distribution and the NACA16009 is used as the desired pressure and vice versa. Using a Savitsky-Golay gradient filter, convergence (defined as a cost function<1E-5) is reached in approximately 220 design iteration using 121 design variables. The inverse-design using inviscid adjoint equations results are followed by the discussion of the viscous inverse design results and techniques used to further the convergence of the optimizer. The relationship between limiting step-size and convergence in a line-search optimization is shown to slightly decrease the final cost function at significant computational cost. A gradient damping technique is presented and shown to increase the convergence rate for the optimization in viscous problems, at a negligible increase in computational cost, but is insufficient to converge the solution. Systematically including adjacent surface vertices in the perturbation of a design variable, also a surface vertex, is shown to affect the convergence capability of the viscous optimizer. Finally, a comparison of using inviscid adjoint equations, as opposed to viscous adjoint equations, on viscous flow is presented, and the inviscid adjoint paired with viscous flow is found to reduce the cost function further than the viscous adjoint for the presented problem.

Discoidin Domain Receptors: Novel Targets in Breast Cancer Bone Metastasis

DTIC Science & Technology

2017-02-01

BrCa cases with different molecular subtypes, and found a significant inverse association between cytoplasmic DDR1 localization and progesterone...DDR1 antibody, and completed the study of DDR1 expression and association with disease progression with one TMA. We found a significant inverse

A Comparison between Deep and Shallow Stress Fields in Korea Using Earthquake Focal Mechanism Inversions and Hydraulic Fracturing Stress Measurements

NASA Astrophysics Data System (ADS)

Lee, Rayeon; Chang, Chandong; Hong, Tae-kyung; Lee, Junhyung; Bae, Seong-Ho; Park, Eui-Seob; Park, Chan

2016-04-01

We are characterizing stress fields in Korea using two types of stress data: earthquake focal mechanism inversions (FMF) and hydraulic fracturing stress measurements (HF). The earthquake focal mechanism inversion data represent stress conditions at 2-20 km depths, whereas the hydraulic fracturing stress measurements, mostly conducted for geotechnical purposes, have been carried out at depths shallower than 1 km. We classified individual stress data based on the World Stress Map quality ranking scheme. A total of 20 FMF data were classified into A-B quality, possibly representing tectonic stress fields. A total of 83 HF data out of compiled 226 data were classified into B-C quality, which we use for shallow stress field characterization. The tectonic stress, revealed from the FMF data, is characterized by a remarkable consistency in its maximum stress (σ1) directions in and around Korea (N79±2° E), indicating a quite uniform deep stress field throughout. On the other hand, the shallow stress field, represented by HF data, exhibits local variations in σ1 directions, possibly due to effects of topography and geologic structures such as faults. Nonetheless, there is a general similarity in σ1 directions between deep and shallow stress fields. To investigate the shallow stress field statistically, we follow 'the mean orientation and wavelength analysis' suggested by Reiter et al. (2014). After the stress pattern analysis, the resulting stress points distribute sporadically over the country, not covering the entire region evenly. In the western part of Korea, the shallow σ1directions are generally uniform with their search radius reaching 100 km, where the average stress direction agrees well with those of the deep tectonic stress. We note two noticeable differences between shallow and deep stresses in the eastern part of Korea. First, the shallow σ1 orientations are markedly non-uniform in the southeastern part of Korea with their search radius less than 25 km. In this region, the average σ1orientation based on the entire B-C quality stress data is calculated to be 77±37° ; however, the average orientation is somewhat meaningless because of the high standard deviation. The southeastern part of Korea consists mainly of Cretaceous sedimentary basin, geologically younger than the rest of the country, where regional scale faults are intensely populated. The highly scattered stress directions in this region may represent the effect of the geologic structures on shallow stress field. Second, shallow σ1 directions in the northeastern part of Korea strike consistently to 135±12° , which is deviated by as much as 56° from the deep tectonic stress direction. This region is characterized by high altitude mountainous topography (an elevation of an order of 1 km) with its major ridge axis in the NW-SE direction. We interpret, as a rule of thumb, that the ridge-perpendicular shallow horizontal stress components may be weak, leading to the ridge-parallel components to be the maximum. Overall, there are similarity and also difference between shallow and deep stress fields. Thus, it will be necessary to differentiate the strategy to tackle the stress-related problems based on their natures.

Tectonic stress orientations and magnitudes, and friction of faults, deduced from earthquake focal mechanism inversions over the Korean Peninsula

NASA Astrophysics Data System (ADS)

Soh, Inho; Chang, Chandong; Lee, Junhyung; Hong, Tae-Kyung; Park, Eui-Seob

2018-05-01

We characterize the present-day stress state in and around the Korean Peninsula using formal inversions of earthquake focal mechanisms. Two different methods are used to select preferred fault planes in the double-couple focal mechanism solutions: one that minimizes average misfit angle and the other choosing faults with higher instability. We invert selected sets of fault planes for estimating the principal stresses at regularly spaced grid points, using a circular-area data-binning method, where the bin radius is optimized to yield the best possible stress inversion results based on the World Stress Map quality ranking scheme. The inversions using the two methods yield well constrained and fairly comparable results, which indicate that the prevailing stress regime is strike-slip, and the maximum horizontal principal stress (SHmax) is oriented ENE-WSW throughout the study region. Although the orientation of the stresses is consistent across the peninsula, the relative stress magnitude parameter (R-value) varies significantly, from 0.22 in the northwest to 0.89 in the southeast. Based on our knowledge of the R-values and stress regime, and using a value for vertical stress (Sv) estimated from the overburden weight of rock, together with a value for the maximum differential stress (based on the Coulomb friction of faults optimally oriented for slip), we estimate the magnitudes of the two horizontal principal stresses. The horizontal stress magnitudes increase from west to east such that SHmax/Sv ratio rises from 1.5 to 2.4, and the Shmin/Sv ratio from 0.6 to 0.8. The variation in the magnitudes of the tectonic stresses appears to be related to differences in the rigidity of crustal rocks. Using the complete stress tensors, including both orientations and magnitudes, we assess the possible ranges of frictional coefficients for different types of faults. We show that normal and reverse faults have lower frictional coefficients than strike-slip faults, suggesting that the former types of faults can be activated under a strike-slip stress regime. Our observations of the seismicity, with normal faulting concentrated offshore to the northwest and reverse faulting focused offshore to the east, are compatible with the results of our estimates of stress magnitudes.

Plasma carotenoids and tocopherols in relation to prostate-specific antigen (PSA) levels among men with biochemical recurrence of prostate cancer.

PubMed

Antwi, Samuel O; Steck, Susan E; Zhang, Hongmei; Stumm, Lareissa; Zhang, Jiajia; Hurley, Thomas G; Hebert, James R

2015-10-01

Although men presenting with clinically localized prostate cancer (PrCA) often are treated with radical prostatectomy or radiation therapy with curative intent, about 25-40% develop biochemically recurrent PrCA within 5 years of treatment, which has no known cure. Studies suggest that carotenoid and tocopherol intake may be associated with PrCA risk and progression. We examined plasma carotenoid and tocopherol levels in relation to prostate-specific antigen (PSA) levels among men with PSA-defined biochemical recurrence of PrCA. Data analyzed were from a 6-month diet, physical activity and stress-reduction intervention trial conducted in South Carolina among biochemically recurrent PrCA patients (n=39). Plasma carotenoids and tocopherol levels were measured using high-performance liquid chromatography (HPLC). Linear regression was used to estimate least-square means comparing PSA levels of men with high versus low carotenoid/tocopherol levels, adjusting for covariates. After adjusting for baseline PSA level, plasma cis-lutein/zeaxanthin level at 3 months was related inversely to PSA level at 3 months (P=0.0008), while α-tocopherol (P=0.01), β-cryptoxanthin (P=0.01), and all-trans-lycopene (P=0.004) levels at 3 months were related inversely to PSA levels at 6-months. Percent increase in α-tocopherol and trans-β-carotene levels from baseline to month 3 were associated with lower PSA levels at 3 and 6 months. Percent increase in β-cryptoxanthin, cis-lutein/zeaxanthin and all-trans-lycopene were associated with lower PSA levels at 6 months only. Certain plasma carotenoids and tocopherols were related inversely to PSA levels at various timepoints, suggesting that greater intake of foods containing these micronutrients might be beneficial to men with PSA-defined PrCA recurrence. Copyright © 2015. Published by Elsevier Ltd.

Deducing the ancestry of terranes: SHRIMP evidence for South America derived Gondwana fragments in central Europe

NASA Astrophysics Data System (ADS)

Friedl, Gertrude; Finger, Fritz; McNaughton, Neal J.; Fletcher, Ian R.

2000-11-01

We present here an example of how the sensitive high-resolution ion microprobe (SHRIMP) zircon dating method can provide a terrane-specific geochronological fingerprint for a rock and thus help to reveal major tectonic boundaries within orogens. This method, applied to inherited zircons in a ca. 580 Ma metagranitoid rock from the eastern Bohemian Massif, has provided, for the first time in the central European Variscan basement, unequivocal evidence for Mesoproterozoic and late Paleoproterozoic geologic events ca. 1.2 Ga, 1.5 Ga, and 1.65 1.8 Ga. The recognition of such zircon ages has important consequences because it implies that parts of the Precambrian section of Variscan central Europe were originally derived from a Grenvillian cratonic province, as opposed to the common assumption of an African connection. A comparison with previously published SHRIMP data suggests, however, that these Mesoproterozoic and late Paleoproterozoic zircon ages may be restricted to the Moravo-Silesian unit in the eastern Variscides, whereas the Saxothuringian and Moldanubian zones appear to contain a typical north African (i.e., Neoproterozoic plus Eburnian) inherited-zircon age spectrum. This finding supports new tectonic concepts, according to which Variscan Europe is composed of a number of completely unrelated terranes with extremely different paleogeographic origins. The Moravo-Silesian unit can be best interpreted as a peri-Gondwana terrane, which was situated in the realm of the Amazonian cratonic province by the late Precambrian, comparable to the Avalonian terranes of North America and the United Kingdom.

Adjoint tomography of Europe

NASA Astrophysics Data System (ADS)

Zhu, H.; Bozdag, E.; Peter, D. B.; Tromp, J.

2010-12-01

We use spectral-element and adjoint methods to image crustal and upper mantle heterogeneity in Europe. The study area involves the convergent boundaries of the Eurasian, African and Arabian plates and the divergent boundary between the Eurasian and North American plates, making the tectonic structure of this region complex. Our goal is to iteratively fit observed seismograms and improve crustal and upper mantle images by taking advantage of 3D forward and inverse modeling techniques. We use data from 200 earthquakes with magnitudes between 5 and 6 recorded by 262 stations provided by ORFEUS. Crustal model Crust2.0 combined with mantle model S362ANI comprise the initial 3D model. Before the iterative adjoint inversion, we determine earthquake source parameters in the initial 3D model by using 3D Green functions and their Fréchet derivatives with respect to the source parameters (i.e., centroid moment tensor and location). The updated catalog is used in the subsequent structural inversion. Since we concentrate on upper mantle structures which involve anisotropy, transversely isotropic (frequency-dependent) traveltime sensitivity kernels are used in the iterative inversion. Taking advantage of the adjoint method, we use as many measurements as can obtain based on comparisons between observed and synthetic seismograms. FLEXWIN (Maggi et al., 2009) is used to automatically select measurement windows which are analyzed based on a multitaper technique. The bandpass ranges from 15 second to 150 second. Long-period surface waves and short-period body waves are combined in source relocations and structural inversions. A statistical assessments of traveltime anomalies and logarithmic waveform differences is used to characterize the inverted sources and structure.

On the Yield Strength of Oceanic Lithosphere

NASA Astrophysics Data System (ADS)

Jain, C.; Korenaga, J.; Karato, S. I.

2017-12-01

The origin of plate tectonic convection on Earth is intrinsically linked to the reduction in the strength of oceanic lithosphere at plate boundaries. A few mechanisms, such as deep thermal cracking [Korenaga, 2007] and strain localization due to grain-size reduction [e.g., Ricard and Bercovici, 2009], have been proposed to explain this reduction in lithospheric strength, but the significance of these mechanisms can be assessed only if we have accurate estimates on the strength of the undamaged oceanic lithosphere. The Peierls mechanism is likely to govern the rheology of old oceanic lithosphere [Kohlstedt et al., 1995], but the flow-law parameters for the Peierls mechanism suggested by previous studies do not agree with each other. We thus reanalyze the relevant experimental deformation data of olivine aggregates using Markov chain Monte Carlo inversion, which can handle the highly nonlinear constitutive equation of the Peierls mechanism [Korenaga and Karato, 2008; Mullet et al., 2015]. Our inversion results indicate nontrivial nonuniqueness in every flow-law parameter for the Peierls mechanism. Moreover, the resultant flow laws, all of which are consistent with the same experimental data, predict substantially different yield stresses under lithospheric conditions and could therefore have different implications for the origin of plate tectonics. We discuss some future directions to improve our constraints on lithospheric yield strength.

Automated Detection and Modeling of Slow Slip: Case Study of the Cascadia Subduction Zone

NASA Astrophysics Data System (ADS)

Crowell, B. W.; Bock, Y.; Liu, Z.

2012-12-01

The discovery of transient slow slip events over the past decade has changed our understanding of tectonic hazards and the earthquake cycle. Proper geodetic characterization of transient deformation is necessary for studies of regional interseismic, coseismic and postseismic tectonics, and miscalculations can affect our understanding of the regional stress field. We utilize two different methods to create a complete record of slow slip from continuous GPS stations in the Cascadia subduction zone between 1996 and 2012: spatiotemporal principal component analysis (PCA) and the relative strength index (RSI). The PCA is performed on 100 day windows of nearby stations to locate signals that exist across many stations in the network by looking at the ratio of the first two eigenvalues. The RSI is a financial momentum oscillator that looks for changes in individual time series with respect to previous epochs to locate rapid changes, indicative of transient deformation. Using both methods, we create a complete history of slow slip across the Cascadia subduction zone, fully characterizing the timing, progression, and magnitude of events. We inject the results from the automated transient detection into a time-dependent slip inversion and apply a Kalman filter based network inversion method to image the spatiotemporal variation of slip transients along the Cascadia margin.

Stratigraphic record of Pliocene-Pleistocene basin evolution and deformation within the Southern San Andreas Fault Zone, Mecca Hills, California

NASA Astrophysics Data System (ADS)

McNabb, James C.; Dorsey, Rebecca J.; Housen, Bernard A.; Dimitroff, Cassidy W.; Messé, Graham T.

2017-11-01

A thick section of Pliocene-Pleistocene nonmarine sedimentary rocks exposed in the Mecca Hills, California, provides a record of fault-zone evolution along the Coachella Valley segment of the San Andreas fault (SAF). Geologic mapping, measured sections, detailed sedimentology, and paleomagnetic data document a 3-5 Myr history of deformation and sedimentation in this area. SW-side down offset on the Painted Canyon fault (PCF) starting 3.7 Ma resulted in deposition of the Mecca Conglomerate southwest of the fault. The lower member of the Palm Spring Formation accumulated across the PCF from 3.0 to 2.6 Ma during regional subsidence. SW-side up slip on the PCF and related transpressive deformation from 2.6 to 2.3 Ma created a time-transgressive angular unconformity between the lower and upper members of the Palm Spring Formation. The upper member accumulated in discrete fault-bounded depocenters until initiation of modern deformation, uplift, and basin inversion starting at 0.7 Ma. Some spatially restricted deposits can be attributed to the evolution of fault-zone geometric complexities. However, the deformation events at ca. 2.6 Ma and 0.7 Ma are recorded regionally along 80 km of the SAF through Coachella Valley, covering an area much larger than mapped fault-zone irregularities, and thus require regional explanations. We therefore conclude that late Cenozoic deformation and sedimentation along the SAF in Coachella Valley has been controlled by a combination of regional tectonic drivers and local deformation due to dextral slip through fault-zone complexities. We further propose a kinematic link between the 2.6-2.3 Ma angular unconformity and a previously documented but poorly dated reorganization of plate-boundary faults in the northern Gulf of California at 3.3-2.0 Ma. This analysis highlights the potential for high-precision chronologies in deformed terrestrial deposits to provide improved understanding of local- to regional-scale structural controls on basin formation and deformation along an active transform margin.

Crustal structure of the northern Menderes Massif, western Turkey, imaged by joint gravity and magnetic inversion

NASA Astrophysics Data System (ADS)

Gessner, Klaus; Gallardo, Luis A.; Wedin, Francis; Sener, Kerim

2016-10-01

In western Anatolia, the Anatolide domain of the Tethyan orogen is exposed in one of the Earth's largest metamorphic core complexes, the Menderes Massif. The Menderes Massif experienced a two-stage exhumation: tectonic denudation in the footwall of a north-directed Miocene extensional detachment, followed by fragmentation by E-W and NW-SE-trending graben systems. Along the northern boundary of the core complex, the tectonic units of the Vardar-Izmir-Ankara suture zone overly the stage one footwall of the core complex, the northern Menderes Massif. In this study, we explore the structure of the upper crust in the northern Menderes Massif with cross-gradient joint inversion of gravity and aeromagnetic data along a series of 10-km-deep profiles. Our inversions, which are based on gravity and aeromagnetic measurements and require no geological and petrophysical constraints, reveal the salient features of the Earth's upper crust. We image the northern Menderes Massif as a relatively homogenous domain of low magnetization and medium to high density, with local anomalies related to the effect of interspersed igneous bodies and shallow basins. In contrast, both the northern and western boundaries of the northern Menderes Massif stand out as domains where dense mafic, metasedimentary and ultramafic domains with a weak magnetic signature alternate with low-density igneous complexes with high magnetization. With our technique, we are able to delineate Miocene basins and igneous complexes, and map the boundary between intermediate to mafic-dominated subduction-accretion units of the suture zone and the underlying felsic crust of the Menderes Massif. We demonstrate that joint gravity and magnetic inversion are not only capable of imaging local and regional changes in crustal composition, but can also be used to map discontinuities of geodynamic significance such as the Vardar-Izmir-Ankara suture and the West Anatolia Transfer Zone.

Outgassing of planets in relation to their obital frequencies

NASA Astrophysics Data System (ADS)

Kochemasov, G.

Planetary atmospheres as inseparable parts of their geospheres have close structural and compositional ties with underlying solid formations. The comparative wave planetology having stated that "orbits make structures" finds that two fundamental properties of all celestial bodies are most important for their structurization: movement and rotation. All bodies move in non-round keplerian elliptic (and parabolic) orbits that implies periodic change of accelerations and delivery of inertia-gravity forces producing warping waves. In rotating bodies (but all celestial bodies rotate !) these waves are ordered in 4 ortho- and diagonal directions. Having stationary character and various lengths they interfere producing positive (+), negative (-) and neutral (0) tectonic blocks. The fundamental wave 1 long 2πR give ubiquitous tectonic dichotomy, the first overtone wave 2 makes tectonic sectoring. Individual for any body waves whose lengths are inversely proportional to their orbital frequencies produce tectonic granules: higher frequency - smaller granule. The following row shows increasing granule sizes (a half of a wavelength, Earth as a scale): Titan πR/91, Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1. One may say that Venus is tectonically "fine-grained", Earth "medium-grained", Mars "coarse-grained". The wave produced granulation indicates that fine-grained Venus is more thoroughly shaken out and released of its volatiles (degassed) than Earth and Mars. This is proved by its massive atmosphere containing a large amount of nitrogen and having very low ratio of radiogenic to primordial argon (Venus 1, Earth 300, Mars 3000). Compare "sweeping" volatiles out of Venus and Earth [1]. Venus is 3.38 times finer-grained than Earth (in the terrestrial globe there are 16.5 grains of radius πR/8, in the venusian one 55.7 grains of radius πR/12; 55.7 : 16.5=3.38). To the terrestrial wavelength 10000 km (πR/2) corresponds frequency 0.03 khz, to the venusian 6000 km (πR/3) 0.07 khz. Venusian oscillations thus 2.33 times more frequent. If a degassing difference of two planets is the square (degassing goes through surface) of the production of differences in granulation and oscillation frequencies, then Venus is 62 times more outgassed [Dv /De = (3.38 x 2.33)2 =62.1]. Actually the venusian atmosphere is 90 times more massive than the terrestrial one. Comparing Mars (1/10th of the Earth's mass) and Earth by the same method we get 920 times less massive martian atmosphere (actually only about 200 times). The discrepancy probably is due to large amounts of volatiles in soils and crust (ice, aqueous salts, zeolites) exchanging them with atmosphere under changing conditions. On contrary, Mercury is completely "shaken out", 1 dry, its would-be massive atmosphere is completely eliminated by solar wind. The smaller volatile rich Titan with high orbital frequency has an important atmosphere -probably only remnants of what was totally outgassed during eons. All Titan's dark plains (frozen methane?) are intensively warped by cross-cutting ridge-groove systems -a consequence of an important subsidence, loosing radius. So, there is an inverse relation between atmospheric masses and a volatile stock in planets. Dry Venus has a massive atmosphere, wet Mars has a weak one. Earth is in the middle: rather wet interior and an important atmosphere. Most outgassed Mercury with distinct traces of earlier contraction (escarps or lobate ledges), alas, has lost its gaseous envelope. Asteroids , next to Mars, as show carboneceous chondrites are rich in volatiles. Sharing an angular momentum between a solid body and a massive gaseous envelope enforces this body rotate slower (Venus, Mercury). This observation could perhaps explain one enigmatic situation: the larger asteroids rotate faster than smaller ones. A reason: the former less wasted their "original" momentum not spending it with loosing volatiles than the latter, more degassed. References: [1] Kochemaov G.G. (2003) Tectonically and chemically dichotomic Mars is the least outgassed of terrestrial planets // Vernadsky-Brown microsymp. 38, Oct. 27-29, 2003, Vernadsky Inst., Moscow, Russia, Abstr.,(CD-ROM). 2

Geometry and active tectonics of the Los Osos-Hosgri Fault Intersection in Estero Bay, CA: Reconciling seismicity patterns with near-surface geology

NASA Astrophysics Data System (ADS)

Watt, J. T.; Hardebeck, J.; Johnson, S. Y.; Kluesner, J.

2016-12-01

Characterizing active structures within structurally complex fault intersections is essential for unraveling the deformational history and for assessing the importance of fault intersections in regional earthquake hazard assessments. We employ an integrative, multi-scale geophysical approach to describe the 3D geometry and active tectonics of the offshore Los Osos fault (LOF) in Estero Bay, California. The shallow structure of the LOF, as imaged with multibeam and high-resolution seismic-reflection data, reveals a complex west-diverging zone of active faulting that bends into and joins the Hosgri fault. The down-dip geometry of the LOF as revealed by gravity, magnetic, and industry multi-channel seismic data, is vertical to steeply-dipping and varies along strike. As the LOF extends offshore, it is characterized by SW-side-up motion on a series of W-NW trending, steeply SW-dipping reverse faults. The LOF bends to the north ( 23°) as it approaches the Hosgri fault and dips steeply to the NE along a magnetic basement block. Inversion of earthquake focal mechanisms within Estero Bay yields maximum compressive stress axes that are near-horizontal and trend approximately N15E. This trend is consistent with dextral strike-slip faulting along NW-SE trending structures such as the Hosgri fault and northern LOF, and oblique dip-slip motion along the W-NW trending section of the LOF. Notably, NW-SE trending structures illuminated by seismicity in Estero Bay coincide with, but also appear to cross-cut, LOF structures imaged in the near-surface. We suggest this apparent disconnect reflects ongoing fault reorganization at a dynamic and inherently unstable fault intersection, in which the seismicity reflects active deformation at depth that is not clearly expressed in the near-surface geology. Direct connectivity between the Hosgri and Los Osos faults suggests a combined earthquake rupture is possible; however, the geometrical complexity along the offshore LOF may limit the extent of rupture.

A framework for predicting global silicate weathering and CO2 drawdown rates over geologic time-scales.

PubMed

Hilley, George E; Porder, Stephen

2008-11-04

Global silicate weathering drives long-time-scale fluctuations in atmospheric CO(2). While tectonics, climate, and rock-type influence silicate weathering, it is unclear how these factors combine to drive global rates. Here, we explore whether local erosion rates, GCM-derived dust fluxes, temperature, and water balance can capture global variation in silicate weathering. Our spatially explicit approach predicts 1.9-4.6 x 10(13) mols of Si weathered globally per year, within a factor of 4-10 of estimates of global silicate fluxes derived from riverine measurements. Similarly, our watershed-based estimates are within a factor of 4-18 (mean of 5.3) of the silica fluxes measured in the world's ten largest rivers. Eighty percent of total global silicate weathering product traveling as dissolved load occurs within a narrow range (0.01-0.5 mm/year) of erosion rates. Assuming each mol of Mg or Ca reacts with 1 mol of CO(2), 1.5-3.3 x 10(8) tons/year of CO(2) is consumed by silicate weathering, consistent with previously published estimates. Approximately 50% of this drawdown occurs in the world's active mountain belts, emphasizing the importance of tectonic regulation of global climate over geologic timescales.

Tectonically Undulating Terrestrial Geospheres and Concordant Development of Two Distinct Somatic Types of Man

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

The human organisms in microgravity conditions loss Ca or become less dense. But variously dense men also develop on Earth due to varying tectonics. As any celestial body, Earth is not a billiard-ball but is complexly warped by a number of standing waves imprinted in the geoid shape. The fundamental wave (long 2π R, R- planet radius) makes tectonic dichotomy (an opposition of the eastern and western oceanic hemispheres), the first overtone (π R) makes sectoring: on the continental eastern hemisphere, for example, around the Pamirs-Hindukush converge 4 sectors. They are 2 opposed differently uplifted (African ++, Asian +) separated by 2 opposed differently subsided (Eurasian -, Indoceanic - -). In rotating Earth the alternating uplifts (++, +) and subsidences (- -, -) require materials of different densities: less dense for uplifts and denser for subsidences. This requirement concerns all geospheres including anthroposphere. The long development of Homo sapiens adapting to graviconditions of uplifting and subsiding blocks produced two distinct somatic types of man: long and narrow (slim) leptosomes and short and broad eirisomes. As shows F. Weidenreich [1], this fundamental division appeared very early in the human history and is observed in all great human races and even in apes. A block uplifting (an increase of the planetary radius) requires diminishing density. This is achieved by distributing the man's weight by the longer stature. Thus appears long and slim leptosome. On the contrary, a block subsidence (diminishing radius) requires increasing density: man is shorter and broader (eirisome). A long existence on intensively moving (up or down) blocks makes these somatic types characteristic of races. Thus, many African tribes developing on intensively moving up continent (more than one kilometer in a few mln. y. ) are leptosomatic; on the contrary, Indians of subsiding western hemisphere are typically eirisomatic with high Rohrer's index; Polynesians of Pacific are high but corpulent, the Rohrer' index is also high. Short in time cosmic experiments (abrupt uplifting) with a sharp drop in gravity produce noticeable effect of Ca leaching out of organism making it less dense. Sure, changing gravity influences not only bones but also flesh, blood, hairs and eventually genes. The frequencies of genetic markers of Rh-system in blood of inhabitants of 4 variously leveled sectors and subsided western hemisphere are clearly different. References: [1] F. Weidenreich. Rasse und Körperbau (in Russian translation, State Publishing House, Moscow-Leningrad, 1929, 271 pp.).

New aerogravity and aeromagnetic anomaly data over Lomonosov Ridge and adjacent areas for bathymetric and tectonic mapping

NASA Astrophysics Data System (ADS)

Dossing, A.; Olesen, A. V.; Forsberg, R.

2010-12-01

Results of an 800 x 800 km aero-gravity and aeromagnetic survey (LOMGRAV) of the southern Lomonosov Ridge and surrounding area are presented. The survey was acquired by the Danish National Space Center, DTU in cooperation with National Resources Canada in spring 2009 as a net of ~NE-SW flight lines spaced 8-10 km apart. Nominal flight level was 2000 ft. We have compiled a detailed 2.5x2.5 km gravity anomaly grid based on the LOMGRAV data and existing data from the southern Arctic Ocean (NRL98/99) and the North Greenland continental margin (KMS98/99). The gravity grid reveals detailed, elongated high-low anomaly patterns over the Lomonosov Ridge which is interpreted as the presence of narrow ridges and subbasins. Distinct local topography is also interpreted over the southernmost part of the Lomonosov Ridge where existing bathymetry compilations suggest a smooth topography due to the lack of data. A new bathymetry model is presented for the region predicted by formalized inversion of the available gravity data. Finally, a detailed magnetic anomaly grid has been compiled from the LOMGRAV data and existing NRL98/99 and PMAP data. New tectonic features are revealed, particularly in the Amerasia Basin, compared with existing magnetic anomaly data from the region.

Ball-and-socket tectonic rotation during the 2013 Mw 7.7 Balochistan earthquake

NASA Astrophysics Data System (ADS)

Barnhart, W. D.; Hayes, G. P.; Briggs, R. W.; Gold, R. D.; Bilham, R.

2014-10-01

The September 2013 Mw 7.7 Balochistan earthquake ruptured a ∼200-km-long segment of the curved Hoshab fault in southern Pakistan with 10 ± 0.2 m of peak sinistral and ∼ 1.7 ± 0.8 m of dip slip. This rupture is unusual because the fault dips 60 ± 15° towards the focus of a small circle centered in northwest Pakistan, and, despite a 30° increase in obliquity along strike, the ratios of strike and dip slip remain relatively uniform. Surface displacements and geodetic and teleseismic source inversions quantify a bilateral rupture that propagated rapidly at shallow depths from a transtensional jog near the northern end of the rupture. Static friction prior to rupture was unusually weak (μ < 0.05), and friction may have approached zero during dynamic rupture. Here we show that the inward-dipping Hoshab fault defines the northern rim of a structural unit in southeast Makran that rotates - akin to a 2-D ball-and-socket joint - counter-clockwise in response to India's penetration into the Eurasian plate. This rotation accounts for complexity in the Chaman fault system and, in principle, reduces seismic potential near Karachi; nonetheless, these findings highlight deficiencies in strong ground motion equations and tectonic models that invoke Anderson-Byerlee faulting predictions.

Ball-and-socket tectonic rotation during the 2013 Mw7.7 Balochistan earthquake

USGS Publications Warehouse

Barnhart, William D.; Hayes, Gavin P.; Briggs, Richard W.; Gold, Ryan D.; Bilham, R.

2014-01-01

The September 2013 Mw7.7 Balochistan earthquake ruptured a ∼200-km-long segment of the curved Hoshab fault in southern Pakistan with 10±0.2 m of peak sinistral and ∼1.7±0.8 m of dip slip. This rupture is unusual because the fault dips 60±15° towards the focus of a small circle centered in northwest Pakistan, and, despite a 30° increase in obliquity along strike, the ratios of strike and dip slip remain relatively uniform. Surface displacements and geodetic and teleseismic source inversions quantify a bilateral rupture that propagated rapidly at shallow depths from a transtensional jog near the northern end of the rupture. Static friction prior to rupture was unusually weak (μ<0.05), and friction may have approached zero during dynamic rupture. Here we show that the inward-dipping Hoshab fault defines the northern rim of a structural unit in southeast Makran that rotates – akin to a 2-D ball-and-socket joint – counter-clockwise in response to India's penetration into the Eurasian plate. This rotation accounts for complexity in the Chaman fault system and, in principle, reduces seismic potential near Karachi; nonetheless, these findings highlight deficiencies in strong ground motion equations and tectonic models that invoke Anderson–Byerlee faulting predictions.

Marine Carbonate Component in the Mantle Beneath the Southeastern Tibetan Plateau: Evidence From Magnesium and Calcium Isotopes

NASA Astrophysics Data System (ADS)

Liu, Fang; Li, Xin; Wang, Guiqin; Liu, Yufei; Zhu, Hongli; Kang, Jinting; Huang, Fang; Sun, Weidong; Xia, Xiaoping; Zhang, Zhaofeng

2017-12-01

Tracing and identifying recycled carbonates is a key issue to reconstruct the deep carbon cycle. To better understand carbonate subduction and recycling beneath the southeastern Tibetan Plateau, high-K cal-alkaline volcanic rocks including trachy-basalts and trachy-andesites from Tengchong were studied using Mg and Ca isotopes. The low δ26Mg (-0.31 ± 0.03‰ to -0.38 ± 0.03‰) and δ44/40Ca (0.67 ± 0.07‰ to 0.80 ± 0.04‰) values of these volcanic rocks compared to those of the mantle (-0.25 ± 0.07‰ and 0.94 ± 0.05‰, respectively) indicate the incorporation of isotopically light materials into the mantle source, which may be carbonate-bearing sediments with low δ26Mg and δ44/40Ca values. In addition, no correlations of δ26Mg and δ44/40Ca with either SiO2 contents or trace element abundance ratios (e.g., Sm/Yb and Ba/Y) were observed, suggesting that limited Mg and Ca isotopic fractionation occurred during cal-alkaline magmatic differentiation. A binary mixing model using Mg-Ca isotopes shows that 5-8% carbonates dominated primarily by dolostone were recycled back into the mantle. Since Tengchong volcanism is still active and probably related to ongoing plate tectonic movement, we propose that the recycled carbonates are derived from oceanic crust related to the ongoing subduction of the Indian plate.

Crustal Scale Magnetotelluric Imaging of the Central Atlas in Moocco

NASA Astrophysics Data System (ADS)

Ledo, J.; Jones, A. G.; Sinischalchi, A.; Rouais, M.; Campanyà, J.; Kiyan, D.; Moretti, P.; Piña, P.; Hogg, C.; Romano, G.; Picasso Team

2010-12-01

The Central Atlas of Morocco is an intracontinental fold-thrust belt with an ENE-WSW main strike that extends about 2000 km and 100 km wide, located in the foreland of the Mediterranean Alpine belt. The structure of the Atlas resulted from the tectonic inversion of a Mesozoic extensional basin, due to compression related to convergence between Africa and Europe occurred from cenozoic to present times. Previous MT data models based on stitched 1D inversion or using only the phases and the induction vector data following and trial and error approach (Schwarz et al., 1992), therefore the overall geoelectrical structure is partly unresolved. In this paper we will expose and discuss the results of new magnetotelluric data acquired along a profile crossing the Atlas that allows imaging its electrical crustal structure.In the lower crust two conductive units appear. One below the Moulouya plains that coincides with a minimum of the Bouguer anomaly, less earthquakes than the adjacent Middle and High Atlas and a low velocity anomaly at lower crustal levels. Moreover, the Moulouya plain and the Middle Atlas to the north are host of the largest Neogene-Quaternary intraplate alkaline volcanic field in Morocco. This feature has been associated either to a Canary mantle plume flow beneath Africa or to the interplay between reactivation of inherited geological structures and the thermal erosion of the metasomatized lithosphere. In any case, all the authors agree that are originated by low degree partial melting of sublithospheric mantle sources. Another low resistivity anomaly appears at lower crustal depths below the Anti-Atlas, that could be either a remnant of tectonic processes in the pre-mesozoic or a more recent overprint of the lower crust due to mantle processes. Two main events during the Pan African orogeny may be the cause of this anomaly, a relic of a subduction process or a deep mineralization associated to magmatism. The Anti-Atlas consists of of a Precambrian crystalline basement that collided at approximately 685 Ma with and oceanic convergent margin together with and ophiolitic assemblage (Saghro, Bou Azzer). The low resistivity structure could be associated to relic subducted oceanic sediments. On the other hand, the Anti-Atlas was affected at the end of the Pan-African orogeny (ca 585-560 Ma) by high-K calc-alkaline and alkaline magmatism. The proterozoic inliers in the Anti-Atlas are highly mineralized, among them, the Imiter Ag deposit is one of the largest silver deposits in the world.

Casting of Halide and Fluoride Alloys for Laser Windows

DTIC Science & Technology

1974-07-15

mechanism leads to an inverse square root dependence of fracture strength on grain size. Since CaF2, SrFp and BaFp all exhibit at least microplastic ...flaws or microplasticity is the strength limiting factor is not known. 4.2.2 Solid-solution strengthening 4.2.2. 1 General If fracture in these...Temperature Microplasticity in SrF2 Single Crystals, " J. Appl. Phys. 41_(4) 1871 (1970). 12. T.S. Liu and C.H. Li, " Plasticity of Barium Fluoride

Chronology, geochemistry and Sr-Nd isotope studies of Jurassic intrusions in the Diyanqinamu porphyry Mo mine, central Inner Mongolia, China

NASA Astrophysics Data System (ADS)

Sun, Hairui; Huang, Zhilong; Li, Wenbo; Leng, Chengbiao; Ma, Deyun; Zhang, Xingchun

2014-07-01

Available cores of porphyritic granite and aplitic granite from the Diyanqinamu porphyry Mo deposit in the north central Great Xing’an Range presented an opportunity to examine and analyze Mesozoic igneous rocks far from the Paleo-Pacific subduction zone. The Diyanqinamu granites are highly fractionated I-type, distinguished from the M-, A- or S-type granite by: high SiO2, and Rb; low Zr, Nb, Y, and Ce; low Fe2O3total/MgO and (K2O + Na2O)/CaO ratios; low alumina saturation index (<1.1); low initial ISr ratios (0.70137-0.70451); positive εNd(t) values (2.37-3.77); and negative correlation between P2O5 and SiO2. The aplitic granites were generated by fractional crystallization of the porphyritic granite, as evidenced by: spatial proximity; consistent zircon U-Pb ages (156 Ma) within error; correlations between other oxides and SiO2 in Haker diagrams; low Ba, Sr, Nb, P, Ti, Eu; linear relationship in both (La/Yb)N vs. La and Sr vs. Ba diagrams; and, decreasing LREE and ∑REE with increasing SiO2. The Diyanqinamu granites have young depleted-mantle two-stage model ages (avg. TDM2 = 660 Ma) similar to those of most Mesozoic voluminous felsic magmas in northeastern China, and were likely sourced from pre-existent crustal components both “old” and juvenile that had been juxtaposed during the tectonic evolution of the Paleo-Asian Ocean. These granites project in the transitional field from syn-collision to post-collision tectonic settings on tectonic discrimination diagrams, implying emplacement in an extensional environment. Extensional volcanism and basin formation in the Great Xing’an Range region in Late Jurassic is coeval with the Diyanqinamu granites, demonstrating that post-orogenic lithospheric extension related to the closure of the Mongol-Okhotsk Ocean was the main driving force for Late Jurassic magmatism in this region.

Mineral chemistry of isotropic gabbros from the Manamedu Ophiolite Complex, Cauvery Suture Zone, southern India: Evidence for neoproterozoic suprasubduction zone tectonics

NASA Astrophysics Data System (ADS)

Yellappa, T.; Tsunogae, T.; Chetty, T. R. K.; Santosh, M.

2016-11-01

The dismembered units of the Neoproterozoic Manamedu Ophiolite Complex (MOC) in the Cauvery Suture Zone, southern India comprises a well preserved ophiolitic sequence of ultramafic cumulates of altered dunites, pyroxenites, mafic cumulates of gabbros, gabbro-norites and anorthosites in association with plagiogranites, isotropic gabbros, metadolerites, metabasalts/amphibolites and thin layers of ferruginous chert bands. The isotropic gabbros occur as intrusions in association with gabbroic anorthosites, plagiogranite and metabasalts/amphibolites. The gabbros are medium to fine grained with euhedral to subhedral orthopyroxenes, clinopyroxenes and subhedral plagioclase, together with rare amphiboles. Mineral chemistry of isotropic gabbros reveal that the clinopyroxenes are diopsidic to augitic in composition within the compositional ranges of En(42-59), Fs(5-12), Wo(31-50). They are Ca-rich and Na poor (Na2O < 0.77 wt%) characterized by high-Mg (Mg# 79-86) and low-Ti (TiO2 < 0.35 wt%) contents. The tectonic discrimination plots of clinopyroxene data indicate island arc signature of the source magma. Our study further confirms the suprasubduction zone origin of the Manamedu ophiolitic suite, associated with the subduction-collision history of the Neoproterozoic Mozambique ocean during the assembly of Gondwana supercontinent.

Ca II 8542 Å brightenings induced by a solar microflare

NASA Astrophysics Data System (ADS)

Kuckein, C.; Diercke, A.; González Manrique, S. J.; Verma, M.; Löhner-Böttcher, J.; Socas-Navarro, H.; Balthasar, H.; Sobotka, M.; Denker, C.

2017-12-01

Aims: We study small-scale brightenings in Ca II 8542 Å line-core images to determine their nature and effect on localized heating and mass transfer in active regions. Methods: High-resolution two-dimensional spectroscopic observations of a solar active region in the near-infrared Ca II 8542 Å line were acquired with the GREGOR Fabry-Pérot Interferometer attached to the 1.5-m GREGOR telescope. Inversions of the spectra were carried out using the NICOLE code to infer temperatures and line-of-sight (LOS) velocities. Response functions of the Ca II line were computed for temperature and LOS velocity variations. Filtergrams of the Atmospheric Imaging Assembly (AIA) and magnetograms of the Helioseismic and Magnetic Imager (HMI) were coaligned to match the ground-based observations and to follow the Ca II brightenings along all available layers of the atmosphere. Results: We identified three brightenings of sizes up to 2'' × 2'' that appeared in the Ca II 8542 Å line-core images. Their lifetimes were at least 1.5 min. We found evidence that the brightenings belonged to the footpoints of a microflare (MF). The properties of the observed brightenings disqualified the scenarios of Ellerman bombs or Interface Region Imaging Spectrograph (IRIS) bombs. However, this MF shared some common properties with flaring active-region fibrils or flaring arch filaments (FAFs): (1) FAFs and MFs are both apparent in chromospheric and coronal layers according to the AIA channels; and (2) both show flaring arches with lifetimes of about 3.0-3.5 min and lengths of 20'' next to the brightenings. The inversions revealed heating by 600 K at the footpoint location in the ambient chromosphere during the impulsive phase. Connecting the footpoints, a dark filamentary structure appeared in the Ca II line-core images. Before the start of the MF, the spectra of this structure already indicated average blueshifts, meaning upward motions of the plasma along the LOS. During the impulsive phase, these velocities increased up to - 2.2 km s-1. The structure did not disappear during the observations. Downflows dominated at the footpoints. However, in the upper photosphere, slight upflows occurred during the impulsive phase. Hence, bidirectional flows are present in the footpoints of the MF. Conclusions: We detected Ca II brightenings that coincided with the footpoint location of an MF. The MF event led to a rise of plasma in the upper photosphere, both before and during the impulsive phase. Excess mass, previously raised to at most chromospheric layers, slowly drained downward along arches toward the footpoints of the MF. The movie associated to Fig. 2 is available at http://www.aanda.org

Gas play opportunities in deeper Jurassic sequences of the Neuquen basin embayment, Argentina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernandez-Seveso, F.; Figueroa, D.E.; Rodriguez, H.

1996-08-01

We have defined new gas plays at around 4000 m depth near the giant Loma La Lata gas field. The plays, in lower Jurassic sandstones, were developed using a different approach in stratigraphic signatures as well as deformation styles. Two initial rifting stages led to the Triassic-Early Liassic volcanoclastic deposition (Precuyo s.l.) into a suite of discrete half-grabens. The late rifting stage amalgamated the Precuyo depocenters into notably extended subsiding half-grabens where the Pliensbachian-Toarcian deposits were accommodated. This lower Cuyo sequence-set (LC) consists of basinal marine shales (Molles Formation) and a progradational stacking of slope and shelf sandstones (Lajas Formation),more » bearing a kerogen type III-II within the gas window with TOC values range 2-6%. The LC top matches with a conspicuous regional unconformity related to the thermo-mechanic subsidence. The overlying Bajocian-early Callovian upper Cuyo sequence set exhibits outer shelf argillaceous sediments at the base. The identified plays are related to two deformation mechanisms: mud diapirism and tectonic inversion. The thick, rapidly deposited LC sandstones triggered the ductile flow of the underlying, overpressured shales. Soon after, the tectonic inversion of the Precuyo half-grabens produced a series of aligned anticlines parallel to Huincul Arch. Scattered incipient diapirism toward the embayment resulted in dome-like structures. Sandstones with gas shows could act as {open_quotes}tight gas reservoirs.{close_quotes} However, increased permeability through natural fracturing in the structures would increase their viability. The estimated resources of several TCF in untested closures and the industry infrastructure make these plays particularly attractive for gas exploration.« less

The Crotone Megalandslide, southern Italy: Architecture, timing and tectonic control.

PubMed

Zecchin, Massimo; Accaino, Flavio; Ceramicola, Silvia; Civile, Dario; Critelli, Salvatore; Da Lio, Cristina; Mangano, Giacomo; Prosser, Giacomo; Teatini, Pietro; Tosi, Luigi

2018-05-17

Large-scale submarine gravitational land movements involving even more than 1,000 m thick sedimentary successions are known as megalandslides. We prove the existence of large-scale gravitational phenomena off the Crotone Basin, a forearc basin located on the Ionian side of Calabria (southern Italy), by seismic, morpho-bathymetric and well data. Our study reveals that the Crotone Megalandslide started moving between Late Zanclean and Early Piacenzian and was triggered by a contractional tectonic event leading to the basin inversion. Seaward gliding of the megalandslide continued until roughly Late Gelasian, and then resumed since Middle Pleistocene with a modest rate. Interestingly, the onshore part of the basin does not show a gravity-driven deformation comparable to that observed in the marine area, and this peculiar evidence allows some speculations on the origin of the megalandslide.

Studies of oceanic tectonics based on GEOS-3 satellite altimetry

NASA Technical Reports Server (NTRS)

Poehls, K. A.; Kaula, W. M.; Schubert, G.; Sandwell, D.

1979-01-01

Using statistical analysis, geoidal admittance (the relationship between the ocean geoid and seafloor topography) obtained from GEOS-3 altimetry was compared to various model admittances. Analysis of several altimetry tracks in the Pacific Ocean demonstrated a low coherence between altimetry and seafloor topography except where the track crosses active or recent tectonic features. However, global statistical studies using the much larger data base of all available gravimetry showed a positive correlation of oceanic gravity with topography. The oceanic lithosphere was modeled by simultaneously inverting surface wave dispersion, topography, and gravity data. Efforts to incorporate geoid data into the inversion showed that the base of the subchannel can be better resolved with geoid rather than gravity data. Thermomechanical models of seafloor spreading taking into account differing plate velocities, heat source distributions, and rock rheologies were discussed.

Early to Middle Ordovician back-arc basin in the southern Appalachian Blue Ridge: characteristics, extent, and tectonic significance

USGS Publications Warehouse

Tull, James; Holm-Denoma, Christopher S.; Barineau, Clinton I.

2014-01-01

Fault-dismembered segments of a distinctive, extensive, highly allochthonous, and tectonically significant Ordovician (ca. 480–460 Ma) basin, which contains suites of bimodal metavolcanic rocks, associated base metal deposits, and thick immature deep-water (turbiditic) metasediments, occur in parts of the southern Appalachian Talladega belt, eastern Blue Ridge, and Inner Piedmont of Alabama, Georgia, and North and South Carolina. The basin's predominantly metasedimentary strata display geochemical and isotopic evidence of a mixed provenance, including an adjacent active volcanic arc and a provenance of mica (clay)-rich sedimentary and felsic plutonic rocks consistent with Laurentian (Grenvillian) upper-crustal continental rocks and their passive-margin cover sequences. Geochemical characteristics of the subordinate intercalated bimodal metavolcanic rocks indicate formation in a suprasubduction environment, most likely a back-arc basin, whereas characteristics of metasedimentary units suggest deposition above Neoproterozoic rift and outer-margin lower Paleozoic slope and rise sediments within a marginal basin along Ordovician Laurentia's Iapetus margin. This tectonic setting indicates that southernmost Appalachian Ordovician orogenesis (Taconic orogeny) began as an extensional accretionary orogen along the outer margin of Laurentia, rather than in an exotic (non-Laurentian) arc collisional setting. B-type subduction polarity requires that the associated arc-trench system formed southeast of the palinspastic position of the back-arc basin. This scenario can explain several unique features of the southern Appalachian Taconic orogen, including: the palinspastic geographic ordering of key tectonic elements (i.e., back-arc, arc, etc.), and a lack of (1) an obducted arc sensu stricto on the Laurentian margin, (2) widespread Ordovician regional metamorphism, and (3) Taconic klippen to supply detritus to the Taconic foreland basin.

Seismo-stratigraphic evolution of the northern Austral Basin and its possible relation to the Andean tectonics, onshore Argentina.

NASA Astrophysics Data System (ADS)

Sachse, Victoria; Anka, Zahie; Pagan, Facundo; Kohler, Guillermina; Cagnolatti, Marcelo; di Primio, Rolando; Rodriguez, Jorge

2013-04-01

The Austral Basin is situated in a formerly and recently high active tectonic zone in southern Argentina. The opening of the South Atlantic to the east, the opening of the Drake Passage in the south, and the subduction related to the rise of the Andes to the west, had major influence on the study area. To identify the impact of the tectonic events on basin geometry, sediment thickness and depocenter migration through time, 2D seismic interpretation was performed for an area of approx. 180.000 km² covering the onshore northern Austral Basin. A total of 10 seismic horizons were mapped and tied to the stratigraphy from well reports, representing 9 syn- and post- rift sequences. The main units are: Basement (U1), Jurassic Tobifera Formation (U2), Early Cretaceous (U3), Late Cretaceous (U4), sub-unit Campanian (U4A), Paleocene (U5), Eocene (U6), Oligocene (U7), Miocene (U8), and Plio-Pleistocene (U9). Main tectonic events are identified representing the break-up phase forming graben systems and the evolution from the ancient backarc Rocas Verdes Basin to the foreland Austral Basin. Inversion and changes in the tectonic regime are concomitant with onlapping and thinning of the base of the Upper Cretaceous to Campanian sediments, while the Top of the Upper Cretaceous represents a Maastrichtian unconformity. Units depth maps show a triangular geometry since the Jurassic, tracing the north-eastern basement high and deepening to the south. Since the Campanian the former geometry of basin fill changed and deepening to the south stopped. Beginning of the foreland phase is assigned to this time as well as changes in the stress regime. Paleogene times are marked by a relatively high sedimentation rate coupled with enduring thermal subsidence, on-going rise of the Andes and changes in the convergence rates of the Nazca relative to the South American plate. Onset of sediment supply from the Andes (Incaic phase) resulted in enhanced sedimentation rates during the Paleocene, coupled with important basin subsidence at Andes foothills. An E-W transpressive deformation occurred during late Oligocene and Miocene, initiated by significant changes of plate motion between Nazca and South American plate, driving the Quechua phase of the Andean uplift. Hence, enhanced sedimentation from the rising Andes was renewed since a late Miocene unconformity.

Insights in Low Frequency Earthquake Source Processes from Observations of Their Size-Duration Scaling

NASA Astrophysics Data System (ADS)

Farge, G.; Shapiro, N.; Frank, W.; Mercury, N.; Vilotte, J. P.

2017-12-01

Low frequency earthquakes (LFE) are detected in association with volcanic and tectonic tremor signals as impulsive, repeated, low frequency (1-5 Hz) events originating from localized sources. While the mechanism causing this depletion of the high frequency content of their signal is still unknown, this feature may indicate that the source processes at the origin of LFE are different from those for regular earthquakes. Tectonic LFE are often associated with slip instabilities in the brittle-ductile transition zones of active faults and volcanic LFE with fluid transport in magmatic and hydrothermal systems. Key constraints on the LFE-generating physical mechanisms can be obtained by establishing scaling laws between their sizes and durations. We apply a simple spectral analysis method to the S-waveforms of each LFE to retrieve its seismic moment and corner frequency. The former characterizes the earthquake's size while the latter is inversely proportional to its duration. First, we analyze a selection of tectonic LFE from the Mexican "Sweet Spot" (Guerrero, Mexico). We find characteristic values of M ˜ 1013 N.m (Mw ˜ 2.6) and fc ˜ 2 Hz. The moment-corner frequency distribution compared to values reported in previous studies in tectonic contexts is consistent with the scaling law suggested by Bostock et al. (2015): fc ˜ M-1/10 . We then apply the same source- parameters determination method to deep volcanic LFE detected in the Klyuchevskoy volcanic group in Kamtchatka, Russia. While the seismic moments for these earthquakes are slightly smaller, they still approximately follow the fc ˜ M-1/10 scaling. This size-duration scaling observed for LFE is very different from the one established for regular earthquakes (fc ˜ M-1/3) and from the scaling more recently suggested by Ide et al. (2007) for the broad class of "slow earthquakes". The scaling observed for LFE suggests that they are generated by sources of nearly constant size with strongly varying intensities. LFE then do not exhibit the self-similarity characteristic of regular earthquakes, strongly suggesting that the physical mechanisms at their origin are different. Moreover, the agreement with the size-duration scaling for both tectonic and volcanic LFE might indicate a similarity in their source behavior.

The depositional setting of the Late Quaternary sedimentary fill in southern Bannu basin, Northwest Himalayan fold and thrust belt, Pakistan.

PubMed

Farid, Asam; Khalid, Perveiz; Jadoon, Khan Zaib; Jouini, Mohammed Soufiane

2014-10-01

Geostatistical variogram and inversion techniques combined with modern visualization tools have made it possible to re-model one-dimensional electrical resistivity data into two-dimensional (2D) models of the near subsurface. The resultant models are capable of extending the original interpretation of the data to depict alluvium layers as individual lithological units within the 2D space. By tuning the variogram parameters used in this approach, it is then possible to visualize individual lithofacies and geomorphological features for these lithologic units. The study re-examines an electrical resistivity dataset collected as part of a groundwater study in an area of the Bannu basin in Pakistan. Additional lithological logs from boreholes throughout the area have been combined with the existing resistivity data for calibration. Tectonic activity during the Himalayan orogeny uplifted and generated significant faulting in the rocks resulting in the formation of a depression which subsequently has been filled with clay-silt and dirty sand facies typical of lacustrine and flood plain environments. Streams arising from adjacent mountains have reworked these facies which have been eroded and replaced by gravel-sand facies along channels. It is concluded that the sediments have been deposited as prograding fan shaped bodies, flood plain, and lacustrine deposits. Clay-silt facies mark the locations of paleo depressions or lake environments, which have changed position over time due to local tectonic activity and sedimentation. The Lakki plain alluvial system has thus formed as a result of local tectonic activity with fluvial erosion and deposition characterized by coarse sediments with high electrical resistivities near the mountain ranges and fine sediments with medium to low electrical resistivities towards the basin center.

Spectropolarimetric Inversions of the Ca II 8542 Å Line in an M-class Solar Flare

NASA Astrophysics Data System (ADS)

Kuridze, D.; Henriques, V. M. J.; Mathioudakis, M.; Rouppe van der Voort, L.; de la Cruz Rodríguez, J.; Carlsson, M.

2018-06-01

We study the M1.9-class solar flare SOL2015-09-27T10:40 UT using high-resolution full Stokes imaging spectropolarimetry of the Ca II 8542 Å line obtained with the CRISP imaging spectropolarimeter at the Swedish 1-m Solar Telescope. Spectropolarimetric inversions using the non-LTE code NICOLE are used to construct semiempirical models of the flaring atmosphere to investigate the structure and evolution of the flare temperature and magnetic field. A comparison of the temperature stratification in flaring and nonflaring areas reveals strong heating of the flare ribbon during the flare peak. The polarization signals of the ribbon in the chromosphere during the flare maximum become stronger when compared to its surroundings and to pre- and post-flare profiles. Furthermore, a comparison of the response functions to perturbations in the line-of-sight magnetic field and temperature in flaring and nonflaring atmospheres shows that during the flare, the Ca II 8542 Å line is more sensitive to the lower atmosphere where the magnetic field is expected to be stronger. The chromospheric magnetic field was also determined with the weak-field approximation, which led to results similar to those obtained with the NICOLE inversions.

Stress regimes in the northwest of Iran from stress inversion of earthquake focal mechanisms

NASA Astrophysics Data System (ADS)

Afra, Mahsa; Moradi, Ali; Pakzad, Mehrdad

2017-11-01

Northwestern Iran is one of the seismically active regions with a high seismic risk in the world. This area is a part of the complex tectonic system due to the interaction between Arabia, Anatolia and Eurasia. The purpose of this study is to deduce the stress regimes in the northwestern Iran and surrounding regions from stress inversion of earthquake focal mechanisms. We compile 92 focal mechanisms data from the Global CMT catalogue and other sources and also determine the focal mechanisms of 14 earthquakes applying the moment tensor inversion. We divide the studied region into 9 zones using similarity of the horizontal GPS velocities and existing focal mechanisms. We implement two stress inversion methods, Multiple Inverse Method and Iterative Joint Inversion Method, which provide comparable results in terms of orientations of maximum horizontal stress axes SHmax. The similar results of the two methods should make us more confident about the interpretations. We consider zones of exclusion surrounding all the earthquakes according to independent focal mechanisms hypothesis. The hypothesis says that the inversion should involve events that are far enough from each other in order that any previous event doesn't affect the stress field near the earthquake under consideration. Accordingly we deal with the matter by considering zones of exclusion around all the events. The result of exclusion is only significant for eastern Anatolia. The stress regime in this region changes from oblique to strike slip faulting because of the exclusion. In eastern Anatolia, the direction of maximum horizontal stress is nearly north-south. The direction alters to east-west in Talesh region. Errors of σ1 are lower in all zones comparing with errors of σ2 and σ3 and there is a trade-off between data resolution and covariance of the model. The results substantiate the strike-slip and thrust faulting stress regimes in the northwest of Iran.

Inverse agonism at the P2Y12 receptor and ENT1 transporter blockade contribute to platelet inhibition by ticagrelor.

PubMed

Aungraheeta, Riyaad; Conibear, Alexandra; Butler, Mark; Kelly, Eamonn; Nylander, Sven; Mumford, Andrew; Mundell, Stuart J

2016-12-08

Ticagrelor is a potent antagonist of the P2Y 12 receptor (P2Y 12 R) and consequently an inhibitor of platelet activity effective in the treatment of atherothrombosis. Here, we sought to further characterize its molecular mechanism of action. Initial studies showed that ticagrelor promoted a greater inhibition of adenosine 5'-diphosphate (ADP)-induced Ca 2+ release in washed platelets vs other P2Y 12 R antagonists. This additional effect of ticagrelor beyond P2Y 12 R antagonism was in part as a consequence of ticagrelor inhibiting the equilibrative nucleoside transporter 1 (ENT1) on platelets, leading to accumulation of extracellular adenosine and activation of G s -coupled adenosine A 2A receptors. This contributed to an increase in basal cyclic adenosine monophosphate (cAMP) and vasodilator-stimulated phosphoprotein phosphorylation (VASP-P). In addition, ticagrelor increased platelet cAMP and VASP-P in the absence of ADP in an adenosine receptor-independent manner. We hypothesized that this increase originated from a direct effect on basal agonist-independent P2Y 12 R signaling, and this was validated in 1321N1 cells stably transfected with human P2Y 12 R. In these cells, ticagrelor blocked the constitutive agonist-independent activity of the P2Y 12 R, limiting basal G i -coupled signaling and thereby increasing cAMP levels. These data suggest that ticagrelor has the pharmacological profile of an inverse agonist. Based on our results showing insurmountable inhibition of ADP-induced Ca 2+ release and forskolin-induced cAMP, the mode of antagonism of ticagrelor also appears noncompetitive, at least functionally. In summary, our studies describe 2 novel modes of action of ticagrelor, inhibition of platelet ENT1 and inverse agonism at the P2Y 12 R that contribute to its effective inhibition of platelet activation. © 2016 by The American Society of Hematology.

Remanent magnetization and three-dimensional density model of the Kentucky anomaly region

NASA Technical Reports Server (NTRS)

1982-01-01

Existing software was modified to handle 3-D density and magnetization models of the Kentucky body and is being tested. Gravity and magnetic anomaly data sets are ready for use. A preliminary block model is under construction using the 1:1,000,000 maps. An x-y grid to overlay the 1:2,500,000 Albers maps and keyed to the 1:1,000,000 scale block models was created. Software was developed to generate a smoothed MAGSAT data set over this grid; this is to be input to an inversion program for generating the regional magnetization map. The regional scale 1:2,500,000 map mosaic is being digitized using previous magnetization models, the U.S. magnetic anomaly map, and regional tectonic maps as a guide.

Origin and assessment of deep groundwater inflow in the Ca' Lita landslide using hydrochemistry and in situ monitoring

NASA Astrophysics Data System (ADS)

Cervi, F.; Ronchetti, F.; Martinelli, G.; Bogaard, T. A.; Corsini, A.

2012-06-01

Changes in soil water content, groundwater flow and a rise in pore water pressure are well-known causal or triggering factors for hillslope instability. Rainfall and snowmelt are generally assumed as the only sources of groundwater recharge. This assumption neglects the role of deep water inflow in highly tectonized areas, a factor that can influence long-term pore-pressure regimes and play a role on local slope instability. This paper aims to assess the origin of groundwater in the Ca' Lita landslide (northern Italian Apennines) and to qualify and quantify the aliquot attributable to deep water inflow. The research is essentially based on in situ monitoring and hydrochemical analyses. It involved 5 yr of continuous monitoring of groundwater levels, electrical conductivity and temperature, and with groundwater sampling followed by determination of major ions, tracers (such as Boron and Strontium), and isotopes (Oxygen, Deuterium, Tritium). Leaching experiments on soil samples and water recharge estimation were also carried out. Results show that the groundwater balance in the Ca' Lita landslide must take into account an inflow of highly mineralized Na-SO4 water (more than 9500 μS cm-1) with non-negligible amounts of Chloride (up to 800 mg l-1). The deep water inflow recharges the aquifer hosted in the bedrock underlying the sliding surface (at a rate of about 7800-17 500 m3 yr-1). It also partly recharges the landslide body, where the hydrochemical imprint of deep water mixed with rainfall and snowmelt water was observed. This points to a probable influence of deep water inflow on the mobility of the Ca' Lita landslide, a finding that could be applicable to other large landslides occurring in highly tectonized areas in the northern Apennines or in other mountain chains.

Large Sanjiang basin groups outside of the Songliao Basin Meso-Senozoic Tectonic-sediment evolution and hydrocarbon accumulation

NASA Astrophysics Data System (ADS)

Zheng, M.; Wu, X.

2015-12-01

The basis geological problem is still the bottleneck of the exploration work of the lager Sanjiang basin groups. In general terms, the problems are including the prototype basins and basin forming mechanism of two aspects. In this paper, using the field geological survey and investigation, logging data analysis, seismic data interpretation technical means large Sanjiang basin groups and basin forming mechanism of the prototype are discussed. Main draw the following conclusions： 1. Sanjiang region group-level formation can be completely contrasted. 2. Tension faults, compressive faults, shear structure composition and structure combination of four kinds of compound fracture are mainly developed In the study area. The direction of their distribution can be divided into SN, EW, NNE, NEE, NNW, NWW to other groups of fracture. 3. Large Sanjiang basin has the SN and the EW two main directions of tectonic evolution. Cenozoic basins in Sanjiang region in group formation located the two tectonic domains of ancient Paleo-Asian Ocean and the Pacific Interchange. 4. Large Sanjiang basin has experienced in the late Mesozoic tectonic evolution of two-stage and nine times. The first stage, developmental stage basement, they are ① Since the Mesozoic era and before the Jurassic; ② Early Jurassic period; The second stage, cap stage of development, they are ③ Late Jurassic depression developmental stages of compression; ④ Early Cretaceous rifting stage; ⑤ depression in mid-Early Cretaceous period; ⑥ tensile Early Cretaceous rifting stage; ⑦ inversion of Late Cretaceous tectonic compression stage; ⑧ Paleogene - Neogene; ⑨ After recently Ji Baoquan Sedimentary Ridge. 5. Large Sanjiang basin group is actually a residual basin structure, and Can be divided into left - superimposed (Founder, Tangyuan depression, Hulin Basin), residual - inherited type (Sanjiang basin), residual - reformed (Jixi, Boli, Hegang basin). there are two developed depression and the mechanism of rifting. 6. Sanjiang Basin Suibin Depression, Tangyuan depression, Jixi Cretaceous Tangyuan and Fangzheng rift is the key for further exploration. Yishu graben is a large core of Sanjiang region to find oil, and Paleogene basin is the focus of the external layer system exploration.

The effects of low sodium solutions on intracellular calcium concentration and tension in ferret ventricular muscle.

PubMed

Allen, D G; Eisner, D A; Lab, M J; Orchard, C H

1983-12-01

Papillary muscles from the right ventricles of ferrets were micro-injected with the photoprotein aequorin. Both tension and the light emitted by the aequorin, which is a measure of the free intracellular Ca concentration [( Ca2+]i), were monitored. Exposure of the papillary muscle to a solution in which all the Na had been replaced by K (0 Na(K) solution) resulted in an increase in tension which subsequently slowly decreased. This contracture was associated with a large increase in [Ca2+]i followed by a decrease to a steady-state-level which was often significantly greater than that in Na-containing solutions. If choline, Li or Tris was used instead of K as a substitute for Na, both the contracture and the associated increase of [Ca2+]i were reduced. The effects of depolarization alone (by raising external K at constant Na concentration) were compared with those of Na removal alone (at constant external K concentration). Na removal contributes more than depolarization to the effects of a Na-free, K-containing solution on the contracture and rise of [Ca2+]i. Increasing intracellular Na concentration [( Na+]i), by exposure to strophanthidin (10 mumol/l), increased the magnitude of both the contracture and [Ca2+]i in 0 Na(K) solutions. Conversely, decreasing [Na+]i by exposure to a solution containing a decreased extracellular Na concentration [( Na+]o), decreased the contracture and [Ca2+]i. When contractures were produced by solutions with various [Na+]o, the size of the resulting contracture and [Ca2+]i were inversely related to [Na+]o. No contracture was seen unless [Na+]o was reduced to below 70 mmol/l. A decrease in the extracellular Ca concentration [( Ca2+]o) from 2 to 0.5 mmol/l or an increase to 8 mmol/l produced, respectively, large decreases and increases of the twitch and accompanying Ca transient. However, if [Ca2+]o was changed at the same time as Na was replaced by K there was little effect on either the contracture or the rise of [Ca2+]i. If [Ca2+]o was changed before replacing Na by K then increasing [Ca2+]o from 2 to 8 mmol/l decreased, and decreasing [Ca2+]o from 2 to 0.5 mmol/l increased, the rise of [Ca2+]i produced by replacing Na by K. The difference between this result and that obtained when [Ca2+]o was changed at the same time as Na was removed may be due to changes of [Na+]i produced by prolonged exposure to an altered [Ca2+]o.(ABSTRACT TRUNCATED AT 400 WORDS)

Rifting to India-Asia Reactivation: Multi-phase Structural Evolution of the Barmer Basin, Rajasthan, northwest India

NASA Astrophysics Data System (ADS)

Kelly, M. J.; Bladon, A.; Clarke, S.; Najman, Y.; Copley, A.; Kloppenburg, A.

2015-12-01

The Barmer Basin, situated within the West Indian Rift System, is an intra-cratonic rift basin produced during Gondwana break-up. Despite being a prominent oil and gas province, the structural evolution and context of the rift within northwest India remains poorly understood. Substantial subsurface datasets acquired during hydrocarbon exploration provide an unrivalled tool to investigate the tectonic evolution of the Barmer Basin rift and northwest India during India-Asia collision. Here we present a structural analysis using seismic datasets to investigate Barmer Basin evolution and place findings within the context of northwest India development. Present day rift structural architectures result from superposition of two non-coaxial extensional events; an early mid-Cretaceous rift-oblique event (NW-SE), followed by a main Paleocene rifting phase (NE-SW). Three phases of fault reactivation follow rifting: A transpressive, Late Paleocene inversion along localised E-W and NNE-SSW-trending faults; a widespread Late Paleocene-Early Eocene inversion and Late Miocene-Present Day transpressive strike-slip faulting along NW-SE-trending faults and isolated inversion structures. A major Late Eocene-Miocene unconformity in the basin is also identified, approximately coeval with those identified within the Himalayan foreland basin, suggesting a common cause related to India-Asia collision, and calling into question previous explanations that are not compatible with spatial extension of the unconformity beyond the foreland basin. Although, relatively poorly age constrained, extensional and compressional events within the Barmer Basin can be correlated with regional tectonic processes including the fragmentation of Gondwana, the rapid migration of the Greater Indian continent, to subsequent collision with Asia. New insights into the Barmer Basin development have important implications not only for ongoing hydrocarbon exploration but the temporal evolution of northwest India.

First results from a full-waveform inversion of the African continent using Salvus

NASA Astrophysics Data System (ADS)

van Herwaarden, D. P.; Afanasiev, M.; Krischer, L.; Trampert, J.; Fichtner, A.

2017-12-01

We present the initial results from an elastic full-waveform inversion (FWI) of the African continent which is melded together within the framework of the Collaborative Seismic Earth Model (CSEM) project. The continent of Africa is one of the most geophysically interesting regions on the planet. More specifically, Africa contains the Afar Depression, which is the only place on Earth where incipient seafloor spreading is sub-aerially exposed, along with other anomalous features such as the topography in the south, and several smaller surface expressions such as the Cameroon Volcanic Line and Congo Basin. Despite its significance, relatively few tomographic images exist of Africa, and, as a result, the debate on the geophysical origins of Africa's anomalies is rich and ongoing. Tomographic images of Africa present unique challenges due to uneven station coverage: while tectonically active areas such as the Afar rift are well sampled, much of the continent exhibits a severe lack of seismic stations. And, while Africa is mostly surrounded by tectonically active spreading plate boundaries, the interior of the continent is seismically quiet. To mitigate such issues, our simulation domain is extended to include earthquakes occurring in the South Atlantic and along the western edge of South America. Waveform modelling and inversion is performed using Salvus, a flexible and high-performance software suite based on the spectral-element method. Recently acquired recordings from the AfricaArray and NARS seismic networks are used to complement data obtained from global networks. We hope that this new model presents a fresh high-resolution image of African geodynamic structure, and helps advance the debate regarding the causative mechanisms of its surface anomalies.

Constraining climate sensitivity and continental versus seafloor weathering using an inverse geological carbon cycle model.

PubMed

Krissansen-Totton, Joshua; Catling, David C

2017-05-22

The relative influences of tectonics, continental weathering and seafloor weathering in controlling the geological carbon cycle are unknown. Here we develop a new carbon cycle model that explicitly captures the kinetics of seafloor weathering to investigate carbon fluxes and the evolution of atmospheric CO 2 and ocean pH since 100 Myr ago. We compare model outputs to proxy data, and rigorously constrain model parameters using Bayesian inverse methods. Assuming our forward model is an accurate representation of the carbon cycle, to fit proxies the temperature dependence of continental weathering must be weaker than commonly assumed. We find that 15-31 °C (1σ) surface warming is required to double the continental weathering flux, versus 3-10 °C in previous work. In addition, continental weatherability has increased 1.7-3.3 times since 100 Myr ago, demanding explanation by uplift and sea-level changes. The average Earth system climate sensitivity is  K (1σ) per CO 2 doubling, which is notably higher than fast-feedback estimates. These conclusions are robust to assumptions about outgassing, modern fluxes and seafloor weathering kinetics.

Constraining climate sensitivity and continental versus seafloor weathering using an inverse geological carbon cycle model

PubMed Central

Krissansen-Totton, Joshua; Catling, David C.

2017-01-01

The relative influences of tectonics, continental weathering and seafloor weathering in controlling the geological carbon cycle are unknown. Here we develop a new carbon cycle model that explicitly captures the kinetics of seafloor weathering to investigate carbon fluxes and the evolution of atmospheric CO2 and ocean pH since 100 Myr ago. We compare model outputs to proxy data, and rigorously constrain model parameters using Bayesian inverse methods. Assuming our forward model is an accurate representation of the carbon cycle, to fit proxies the temperature dependence of continental weathering must be weaker than commonly assumed. We find that 15–31 °C (1σ) surface warming is required to double the continental weathering flux, versus 3–10 °C in previous work. In addition, continental weatherability has increased 1.7–3.3 times since 100 Myr ago, demanding explanation by uplift and sea-level changes. The average Earth system climate sensitivity is  K (1σ) per CO2 doubling, which is notably higher than fast-feedback estimates. These conclusions are robust to assumptions about outgassing, modern fluxes and seafloor weathering kinetics. PMID:28530231

Mapping the Earth's thermochemical and anisotropic structure using global surface wave data

NASA Astrophysics Data System (ADS)

Khan, A.; Boschi, L.; Connolly, J. A. D.

2011-01-01

We have inverted global fundamental mode and higher-order Love and Rayleigh wave dispersion data jointly, to find global maps of temperature, composition, and radial seismic anisotropy of the Earth's mantle as well as their uncertainties via a stochastic sampling-based approach. We apply a self-consistent thermodynamic method to systematically compute phase equilibria and physical properties (P and S wave velocity, density) that depend only on composition (in the Na2-CaO-FeO-MgO-Al2O3-SiO2 model system), pressure, and temperature. Our 3-D maps are defined horizontally by 27 different tectonic regions and vertically by a number of layers. We find thermochemical differences between oceans and continents to extend down to ˜250 km depth, with continents and cratons appearing chemically depleted (high magnesium number (Mg #) and Mg/Si ratio) and colder (>100°C) relative to oceans, while young oceanic lithosphere is hotter than its intermediate age and old counterparts. We find what appears to be strong radial S wave anisotropy in the upper mantle down to ˜200 km, while there seems to be little evidence for shear anisotropy at greater depths. At and beneath the transition zone, 3-D heterogeneity is likely uncorrelated with surface tectonics; as a result, our tectonics-based parameterization is tenuous. Despite this weakness, constraints on the gross average thermochemical and anisotropic structure to ˜1300 km depth can be inferred, which appear to indicate that the compositions of the upper (low Mg# and high Mg/Si ratio) and lower mantle (high Mg# and low Mg/Si ratio) might possibly be distinct.

Understanding Himalayan erosion and the significance of the Nicobar Fan

NASA Astrophysics Data System (ADS)

McNeill, Lisa C.; Dugan, Brandon; Backman, Jan; Pickering, Kevin T.; Pouderoux, Hugo F. A.; Henstock, Timothy J.; Petronotis, Katerina E.; Carter, Andrew; Chemale, Farid; Milliken, Kitty L.; Kutterolf, Steffen; Mukoyoshi, Hideki; Chen, Wenhuang; Kachovich, Sarah; Mitchison, Freya L.; Bourlange, Sylvain; Colson, Tobias A.; Frederik, Marina C. G.; Guèrin, Gilles; Hamahashi, Mari; House, Brian M.; Hüpers, Andre; Jeppson, Tamara N.; Kenigsberg, Abby R.; Kuranaga, Mebae; Nair, Nisha; Owari, Satoko; Shan, Yehua; Song, Insun; Torres, Marta E.; Vannucchi, Paola; Vrolijk, Peter J.; Yang, Tao; Zhao, Xixi; Thomas, Ellen

2017-10-01

A holistic view of the Bengal-Nicobar Fan system requires sampling the full sedimentary section of the Nicobar Fan, which was achieved for the first time by International Ocean Discovery Program (IODP) Expedition 362 west of North Sumatra. We identified a distinct rise in sediment accumulation rate (SAR) beginning ∼9.5 Ma and reaching 250-350 m/Myr in the 9.5-2 Ma interval, which equal or far exceed rates on the Bengal Fan at similar latitudes. This marked rise in SAR and a constant Himalayan-derived provenance necessitates a major restructuring of sediment routing in the Bengal-Nicobar submarine fan. This coincides with the inversion of the Eastern Himalayan Shillong Plateau and encroachment of the west-propagating Indo-Burmese wedge, which reduced continental accommodation space and increased sediment supply directly to the fan. Our results challenge a commonly held view that changes in sediment flux seen in the Bengal-Nicobar submarine fan were caused by discrete tectonic or climatic events acting on the Himalayan-Tibetan Plateau. Instead, an interplay of tectonic and climatic processes caused the fan system to develop by punctuated changes rather than gradual progradation.

Study on moderate earthquake risk of the Xinfengjiang reservoir from 3D P-wave velocity structure and current seismicity parameters

NASA Astrophysics Data System (ADS)

Ye, Xiuwei; Wang, Xiaona; Huang, Yuanmin; Liu, Jiping; Tan, Zhengguang

2017-06-01

In this paper, we determined the Xingfengjiang Reservoir earthquake sequence location from June 2007 to July 2014 and 3D P-wave velocity structure by a simultaneous inversion method. On that basis, we mapped the b-value 3D distribution. The results show the low b-value distribution consists with the high velocity zone(HVZ) and most earthquakes occurred around the HVZ. Under the reservoir dam there is a strong tectonic deformation zone, as the centre exit Renzishi fault F2, Nanshan - Aotou faults F4, Heyuan fault F1 and Shijiao-xingang-baitian fault F5. M6.1 Xinfengjiang earthquake, 19 Mar 1962, occurred in the strong tectonic deformation zone, and now the zone b≥0.7, so a short period of the original earthquake occur more unlikely. The b-value of the HVZ under Xichang(in the northwest corner of XFJ Reservoir) ranges between 0.4 to 0.7 suggesting the rate of stress accumulations is greater than the speed of seismic energy release since 2012. We don’t exclude the possibility that the HVZ becomes the seismogenic asperity, and will occur M≥5 earthquake.

Long-range ordering in the Bi 1-xAe xFeO 3-x/2 perovskites: Bi 1/3Sr 2/3FeO 2.67 and Bi 1/2Ca 1/2FeO 2.75

NASA Astrophysics Data System (ADS)

Lepoittevin, C.; Malo, S.; Barrier, N.; Nguyen, N.; Van Tendeloo, G.; Hervieu, M.

2008-10-01

Two-ordered perovskites, Bi 1/3Sr 2/3FeO 2.67 and Bi 1/2Ca 1/2FeO 2.75, have been stabilized and characterized by transmission electron microscopy, Mössbauer spectroscopy and X-ray powder diffraction techniques. They both exhibit orthorhombic superstructures, one with a≈ b≈2 ap and c≈3 ap (S.G.: Pb2 n or Pbmn) for the Sr-based compound and one with a≈ b≈2 ap and c≈8 ap (S.G.: B222, Bmm2, B2 mm or Bmmm) for the Ca-based one. The high-resolution transmission electron microscopy (HRTEM) images evidence the existence of one deficient [FeO x] ∞ layer, suggesting that Bi 1/3Sr 2/3FeO 2.67 and Bi 1/2Ca 1/2FeO 2.75 behave differently compared to their Ln-based homolog. The HAADF-STEM images allow to propose a model of cation ordering on the A sites of the perovskite. The Mössbauer analyses confirm the trivalent state of iron and its complex environment with three types of coordination. Both compounds exhibit a high value of resistivity and the inverse molar susceptibility versus temperature curves evidence a magnetic transition at about 730 K for the Bi 1/3Sr 2/3FeO 2.67 and a smooth reversible transition between 590 and 650 K for Bi 1/2Ca 1/2FeO 2.75.

Magnetic, hyperthermic and structural properties of zn substituted CaFe2O4 powders

NASA Astrophysics Data System (ADS)

Kheradmand, Abbas; Vahidi, Omid; Masoudpanah, S. M.

2018-03-01

In the present study, we have synthesized single phase Ca1 - x Zn x Fe2O4 powders by hydrothermal method. The cation distribution between the tetrahedral and octahedral sites in the spinel structure and the magnetic properties as a function of the zinc substitution have been investigated by X-ray diffraction (XRD), infrared spectroscopy and vibrating sample magnetometer methods. The obtained XRD pattern indicated that the synthesized particles had single phase cubic spinel structure with no impurity. The magnetic measurements showed that the saturation magnetization increased from 83 to 98 emu/g with the addition of zinc due to the decrease of inversity. The particle size observed by electron microscopy decreased from 1.38 to 0.97 µm with the increase of zinc addition. The Ca0.7Zn0.3Fe2O4 powders exhibited appropriate heating capability for hyperthermia applications with the maximum AC heating temperature of 20 °C and specific loss power of 9.29 W/g.

A reassessment of the Archean-Mesoproterozoic tectonic development of the southeastern Chhattisgarh Basin, Central India through detailed aeromagnetic analysis

NASA Astrophysics Data System (ADS)

Sridhar, M.; Ramesh Babu, V.; Markandeyulu, A.; Raju, B. V. S. N.; Chaturvedi, A. K.; Roy, M. K.

2017-08-01

We constrained the geological framework over polydeformed Paleoproterozoic Sonakhan Greenstone Belt and addressed the tectonic evolution of Singhora basin in the fringes of Bastar Craton, central India by utilizing aeromagnetic data interpretation, 2.5D forward modelling and 3D magnetic susceptibility inversions. The Sonakhan Greenstone Belt exposes volcano-sedimentary sequences of the Sonakhan Group within NNW-SSE to NW-SE trending linear belts surrounded by granite gneisses, which are unconformably overlain by sedimentary rocks of Chhattisgarh Basin. The orientations of aeromagnetic anomalies are coincident with geological trends and appear to correlate with lithology and geologic structure. Regional magnetic anomalies and lineaments reveal both NNW-SSE and NE-SW trends. Prominent E-W trending linear, high amplitude magnetic anomalies are interpreted as the Trans-Chhattisgarh Aeromagnetic Lineament (TCAL). NW-SE trending aeromagnetic signatures related to Sonakhan Greenstone Belt extends below the Singhora sedimentary rocks and forms the basement in the west. The analysis suggests that TCAL is a block fault with northern block down-thrown and affected the basement rocks comprising the Sonakhan Greenstone Belt and Samblapur Granitoids. The episode of faulting represented by the TCAL is pre-Singhora sedimentation and played a vital role in basin evolution. The basement configuration image generated by estimates of depth to magnetic basement suggests a complex pattern of NNE-SSW to NE-SW trending depressions separated by a linear N-S trending basement ridge. It is inferred from the 3D magnetic susceptibility inversion that the thickness of sediments is more towards the eastern basin margin and the N-S ridge is a manifestation of post sedimentary faulting. Results of 2.5D modelling of a WNW-ESE profile across the Singhora Basin combined with results from 3D inversion suggest suggests the basin subsidence was controlled by NE-SW trending regional faults in an active system. The basin geometry evolved by E-W block faulting overprinted by NE-SW trending pre- to syn-depositional normal faults generating NE-SW depression, which are affected by N-S trend post-sedimentary faulting. Though the present work relates the basin evolution with the initiation of rift basin, it warrants further work to establish the deformation within the basin pertaining to the proximal thrust and uplift along the craton fringe.

Removal of chromium (VI) ions from aqueous solutions using amine-impregnated TiO2 nanoparticles modified cellulose acetate membranes.

PubMed

Gebru, Kibrom Alebel; Das, Chandan

2018-01-01

In this work, TiO 2 nanoparticles (NPs) were modified using tetraethylenepentamine (TEPA), ethylenediamine (EDA), and hexamethylenetetramine (HMTA) amines using impregnation process. The prepared amine modified TiO 2 samples were explored as an additive to fabricate ultrafiltration membranes with enhanced capacity towards the removal of chromium ions from aqueous solution. Modified membranes were prepared from cellulose acetate (CA) polymer blended with polyethylene glycol (PEG) additive, and amine modified TiO 2 by using phase inversion technique. Fourier transform infrared spectroscopy (FTIR), zeta potential (ζ), thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), water contact angle (WCA), and atomic absorption spectrophotometer (AAS) studies were done to characterize the membranes in terms of chemical structure, electric charge, thermal stability, morphology, hydrophilicity, and removal performance. The pure water permeability and Cr (VI) ion removal efficiency of the unmodified (i.e. CA/U-Ti) and the amine modified (CA/Ti-HMTA, CA/Ti-EDA, and CA/Ti-TEPA) membranes were dependent on pH and metal ion concentration. Incorporation of amine modified TiO 2 composite to the CA polymer was found to improve the fouling and removal characteristics of the membranes during the chromium ultrafiltration process. The maximum removal efficiency result of Cr (VI) ions at pH of 3.5 using CA/Ti-TEPA membrane was 99.8%. The washing/regeneration cycle results in this study described as an essential part for prospect industrial applications of the prepared membranes. The maximum Cr (VI) removal results by using CA/Ti-TEPA membrane for four washing/regeneration cycles are 99.6%, 99.5%, 98.6% and, 96.6%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Geochronological, geochemical and Sr-Nd-Hf isotopic constraints on the petrogenesis of Late Cretaceous A-type granites from the Sibumasu Block, Southern Myanmar, SE Asia

NASA Astrophysics Data System (ADS)

Jiang, Hai; Li, Wen-Qian; Jiang, Shao-Yong; Wang, He; Wei, Xiao-Peng

2017-01-01

The Late Cretaceous to Paleogene granitoids occur widespread in the Sibumasu block within Myanmar (SE Asia), which show a close association with tin-tungsten mineralization. However, the precise timing, petrogenesis and tectonic significance of these granitoids are poorly constrained so far. In this study, we present a detailed study on geochronology, elemental and Sr-Nd-Hf isotopic geochemistry for the Hermyingyi and Taungphila granites in southern Myanmar, with the aim of determining their petrogenesis and tectonic implications. LA-ICP-MS U-Pb dating of zircon grains from the two granites yield ages of 69-70 Ma, indicating a Late Cretaceous magmatic event. These granitic rocks are weakly peraluminous and belong to the high-K calc-alkaline series. They are both characterized by high SiO2, K2O + Na2O, FeOT/(FeOT + MgO) and Ga/Al ratios and low Al2O3, CaO, MgO, P2O5 and TiO2 contents, enriched in Rb, Th, U and Y, but depleted in Ba, Sr, P, and Eu, suggesting an A-type granite affinity. Moreover, they display prominent tetrad REE patterns and non-CHARAC trace element behavior, which are common in late magmatic differentiates with strong hydrothermal interaction or deuteric alteration. The granites belong to A2-type and probably formed at a high temperature and anhydrous condition. They have zircon εHf(t) values from - 12.4 to - 10.0 and whole-rock εNd(t) values from - 11.3 to - 10.6, with Paleoproterozoic TDM2 ages (1741-1922 Ma) for both Hf and Nd isotopes. Geochemical and isotopic data suggest that these A-type granites were derived from partial melting of the Paleoproterozoic continental crust dominated by metaigneous rocks with tonalitic to granodioritic compositions, without significant input of mantle-derived magma and followed by subsequent fractional crystallization. By integrating all available data for the regional tectonic evolution in SE Asia and adjacent regions, we attribute the formation of the Late Cretaceous A-type granites to a back-arc extension in the hinterland behind the subduction zone, which is induced by the rollback of the flat Neo-Tethyan subducting slab around ca. 70 Ma. Table 2 Major (wt.%) and trace element (ppm) compositions from the Hermyingyi and Taungphila granites. LOI is loss on ignition; A/CNK = Al2O3/(CaO + Na2O + K2O) (molar ratio); FeOT = FeO + Fe2O3 × 0.8998. Eu/Eu* is a measure of the Eu anomaly when compare to Sm and Gd. Eu/Eu* = EuN/[(SmN) × (GdN)]0.5. Table 3 Sr-Nd isotopic compositions of the Hermyingyi and Taungphila granites. Table 4 Hf isotopic compositions of zircons from the Hermyingyi and Taungphila granites. (176Lu/177Hf)CHUR = 0.0032, (176Hf/177Hf)CHUR,0 = 0.282772 (Blichert-Toft and Albarède, 1997); (176Lu/177Hf)DM = 0.0384, (176Hf/177Hf)DM,0 = 0.28325 (Griffin et al., 2000); λ = 1.867 × 10- 11/year (Soderlund et al., 2004).

Early Functional Connectome Integrity and 1-Year Recovery in Comatose Survivors of Cardiac Arrest.

PubMed

Sair, Haris I; Hannawi, Yousef; Li, Shanshan; Kornbluth, Joshua; Demertzi, Athena; Di Perri, Carol; Chabanne, Russell; Jean, Betty; Benali, Habib; Perlbarg, Vincent; Pekar, James; Luyt, Charles-Edouard; Galanaud, Damien; Velly, Lionel; Puybasset, Louis; Laureys, Steven; Caffo, Brian; Stevens, Robert D

2018-04-01

Purpose To assess whether early brain functional connectivity is associated with functional recovery 1 year after cardiac arrest (CA). Materials and Methods Enrolled in this prospective multicenter cohort were 46 patients who were comatose after CA. Principal outcome was cerebral performance category at 12 months, with favorable outcome (FO) defined as cerebral performance category 1 or 2. All participants underwent multiparametric structural and functional magnetic resonance (MR) imaging less than 4 weeks after CA. Within- and between-network connectivity was measured in dorsal attention network (DAN), default-mode network (DMN), salience network (SN), and executive control network (ECN) by using seed-based analysis of resting-state functional MR imaging data. Structural changes identified with fluid-attenuated inversion recovery and diffusion-weighted imaging sequences were analyzed by using validated morphologic scales. The association between connectivity measures, structural changes, and the principal outcome was explored with multivariable modeling. Results Patients underwent MR imaging a mean 12.6 days ± 5.6 (standard deviation) after CA. At 12 months, 11 patients had an FO. Patients with FO had higher within-DMN connectivity and greater anticorrelation between SN and DMN and between SN and ECN compared with patients with unfavorable outcome, an effect that was maintained after multivariable adjustment. Anticorrelation of SN-DMN predicted outcomes with higher accuracy than fluid-attenuated inversion recovery or diffusion-weighted imaging scores (area under the receiver operating characteristic curves, respectively, 0.88, 0.74, and 0.71). Conclusion MR imaging-based measures of cerebral functional network connectivity obtained in the acute phase of CA were independently associated with FO at 1 year, warranting validation as early markers of long-term recovery potential in patients with anoxic-ischemic encephalopathy. © RSNA, 2017.

Magnetotelluric measurements across the southern Barberton greenstone belt, South Africa: data improving strategies and 2-D inversion results

NASA Astrophysics Data System (ADS)

Kutter, S.; Chen, X.; Weckmann, U.

2011-12-01

Magnetotelluric (MT) measurements in areas with electromagnetic (EM) noise sources such as electric fences, power and railway lines pose severe challenges to the standard processing procedures. In order to significantly improve the data quality advanced filtering and processing techniques need to be applied. The presented 5-component MT data set from two field campaigns in 2009 and 2010 in the Barberton/Badplaas area, South Africa, was acquired within the framework of the German-South African geo-scientific research initiative Inkaba yeAfrica. Approximately 200 MT sites aligned along six profiles provide a good areal coverage of the southern part of the Barberton Greenstone Belt (BGB). Since it is one of the few remaining well-preserved geological formations from the Archean, it presents an ideal area to study the tectonic evolution and the role of plate tectonics on Early Earth. Comparing the electric properties, the surrounding high and low grade metamorphic rocks are characteristically resistive whereas mineralized shear zones are possible areas of higher electrical conductivity. Mapping their depth extension is a crucial step towards understanding the formation and the evolution of the BGB. Unfortunately, in the measurement area numerous noise sources were active, producing severe spikes and steps in the EM fields. These disturbances mainly affect long periods which are needed for resolving the deepest structures. The Remote Reference technique as well as two filtering techniques are applied to improve the data in different period ranges. Adjusting their parameters for each site is necessary to obtain the best possible results. The improved data set is used for two-dimensional inversion studies for the six profiles applying the RLM2DI algorithm by Rodi and Mackie (2001, implemented in WinGlink). In the models, areas with higher conductivity can be traced beneath known faults throughout the entire array along different profiles. Resistive zones seem to correlate well with plutonic intrusions.

Transtensional deformation and structural control of contiguous but independent magmatic systems: Mono-Inyo Craters, Mammoth Mountain, and Long Valley Caldera, California

USGS Publications Warehouse

Riley, P.; Tikoff, B.; Hildreth, Wes

2012-01-01

The Long Valley region of eastern California (United States) is the site of abundant late Tertiary–present magmatism, including three geochemically distinct stages of magmatism since ca. 3 Ma: Mammoth Mountain, the Mono-Inyo volcanic chain, and Long Valley Caldera. We propose two tectonic models, one explaining the Mammoth Mountain–Mono-Inyo magmatism and the other explaining the presence of Long Valley Caldera. First, the ongoing Mammoth Mountain–Mono-Inyo volcanic chain magmatism is explained by a ridge-transform-ridge system, with the Mono-Inyo volcanic chain acting as one ridge segment and the South Moat fault acting as a transform fault. Implicit in this first model is that this region of eastern California is beginning to act as an incipient plate boundary. Second, the older Long Valley Caldera system is hypothesized to occur in a region of enhanced extension resulting from regional fault block rotation, specifically involving activation of the sinistral faults of the Mina deflection. The tectonic models are consistent with observed spatial and temporal differences in the geochemistry of the regional magmas, and the westward progression of magmatism since ca. 12 Ma.

Thermochronology in southeast Alaska and southwest Yukon: Implications for North American Plate response to terrane accretion

NASA Astrophysics Data System (ADS)

Enkelmann, Eva; Piestrzeniewicz, Adam; Falkowski, Sarah; Stübner, Konstanze; Ehlers, Todd A.

2017-01-01

This study presents the first comprehensive dataset of low-temperature thermochronology from 43 bedrock samples collected north of the active Yakutat-North American plate boundary. Our apatite and zircon (U-Th)/He and fission-track data reveal the cooling history of the inboard Wrangellia Composite Terrane that is dominated by rapid cooling after Late Jurassic to Early Cretaceous arc magmatism followed by very little cooling and exhumation until today. Deformation resulting in rock exhumation due to the collision of the Yakutat microplate is spatially very limited (20-30 km) and is concentrated mainly in the Chugach-Prince William Terrane and rocks near the Border Ranges Fault. Focused exhumation from greater depths of ca. 10 km with very high rates (>5 km/Myr) is localized at the syntaxis region, starting ca. 10 Ma and shifted south through time. The rapid exhumation rates are explained by the development of strong feedbacks between tectonically driven surface uplift and erosion, which started already before glaciation of the area. The shift in the location towards the south is a consequence of continuous readjusting between tectonics and climate, which is changing on local and global scales since the Late Miocene.

Influence of fault geometry and tectonic driving stress orientation on the mechanics of multifault earthquakes

NASA Astrophysics Data System (ADS)

Madden, E. H.; Maerten, F.; Pollard, D. D.

2012-12-01

The M 7.3 28 June 1992 Landers, California earthquake was a well-documented event that highlighted the complex relationship between the earthquake and the multiple faults on which it occurred. Not only was fault slip data mapped in the field in detail, due to good exposure in the arid conditions of the Mojave Desert, but also it was one of the first earthquakes for which the surface displacement field was captured by satellite technology. In addition, precise aftershock relocations and fault plane solutions provide information about stress and fault behavior at depth. Study of fault interactions leading to the linkage of five right-lateral, strike-slip faults at Landers is aided by this abundance of available surface and subsurface data. While mapped near-field surface data often are restricted to the realm of the geologist, and subsurface data, such as aftershocks, often are restricted to the realm of the geophysicist, we find that integrating these data in mechanical forward models provides good constraint on the three-dimensional structures of the faults involved. Mechanical models also reveal that fault geometry and the orientation of the tectonic driving stress greatly influence whether or not slip is promoted across the extensional step between two of the faults along the southern-central rupture and elucidate the role of a crossing fault located within the step. Unfortunately, the orientation of the principal stresses are not well constrained near Landers or in many regions around the world. Previous determinations of the tectonic driving stress at Landers range from 7 degrees to 45 degrees, measured clockwise from North. We introduce a new stress inversion method that honors mechanical relationships among the remote stress state that is being inverted for, mainshock fault slip, the resulting total stress field following fault slip, and aftershocks. Use of the principal of superposition in this new algorithm obviates the need for the prohibitive computation times associated with running successive forward models. We apply the inverse method using aftershock, Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning System (GPS) data associated with the Landers earthquake and address how fault geometry and aftershock size, timing, and focal mechanism quality influence inversion results. The advantages of this new method are that: (1) coseismic displacement data can be used, (2) the underlying model is better constrained to find a solution in the parameter space in the presence of fault slip perturbations, (3) absolute magnitudes can be recovered when using data with magnitude information such as GPS, InSAR and stress tensors inferred from aftershocks with known magnitudes. In addition, while one can choose to invert for an Andersonian fault regime, the method is not restricted to that particular case with one vertical principal stress.

Felsic plutonism in the Al Amar—Idsas area, Kingdom of Saudi Arabia

NASA Astrophysics Data System (ADS)

Le Bel, L.; Laval, M.

A tonalite—trondhjemite suite, calc-alkalic plutons and alkali-feldspar granites dated 670 and 580 Ma, intrude thick volcano-sedimentary rocks of the Al Amar group E of the Al Amar fault and the Abt schist W of the fault. The tonalite—trondhjemite suite (group I) is characterized by low Rb (50 ppm) and Sr (100-400 ppm) and by weakly fractionated rare-earth patterns (La/Yb Nca 2-3) with a weak negative Eu anomaly. Calc-alkalic plutons (group II) are richer in Rb (50-150 ppm), contain variable Sr (50-1000 ppm), and have strongly fractionated rare-earth patterns (La/Yb Nca 6-22) with no Eu anomaly. Alkali-feldspar granite (group III) is characterized by high Rb (150-200 ppm) and shows fractionated rare-earth patterns (La/Yb Nca 6-18) with a well-developed Eu anomaly. Group III includes 'specialized granites' with high Rb (300-400 ppm) and Sn (28-66 ppm), and rare-earth patterns showing a distinctive 'sea gull' profile with a very strong Eu anomaly (Eu*/Eu = 20). Oxygen isotope geochemistry suggests that group I rocks (¯x δ18O ca 7.0) were mantle-derived, and that group II and III rocks intruding the Al Amar group ( δ18O ca 7.9 and 8.8 respectively) were derived by remelting of group I, whereas those intruding Abt schist ( δ18O ca 8.7 and 10.8 respectively) were partially derived by anatexis of the Afif block. Magmatogenesis reflects an island-arc development. Rocks of group I represent the initial subduction phase. Syn- to late-tectonic plutons of group II intruded the arc east of the Al Amar fault and the accretionary prism (Abt schist) to the west, which was in collision with the older Afif block. Post-tectonic group III rocks were emplaced in an already cratonized area.

The tectonic evolution of western Central Iran seen through detrital white mica

NASA Astrophysics Data System (ADS)

Kargaranbafghi, Fariba; Neubauer, Franz; Genser, Johann

2015-05-01

A first order survey of 40Ar/39Ar dating of detrital white mica from Jurassic to Pliocene sandstones has been carried out in order to reveal the tectonic evolution of blocks in Central Iran. The Central Iran block was believed to represent a stable Precambrian block. Our results indicate that: (1) Only a very small proportion of Precambrian but abundant Paleozoic and Mesozoic detrital white mica indicate the Phanerozoic, mostly Mesozoic age of metamorphic crust exposed in Central Iran. The oldest but scarce detrital white mica grains have ages ranging from 524 to 826 Ma heralding a Late Precambrian and Cambrian crystalline basement or cannibalism from older clastic successions. (2) Jurassic and Cretaceous sandstones from the west and east of the Chapedony fault yield different age spectra, with a dominance of Variscan ages (ca. 308-385 Ma) in the Biabanak unit west of the Chapedony fault compared to coeval sandstones from the block east of the Chapedony fault, where Variscan ages are subordinate and Cimmerian ages predominate. The micas from the Biabanak unit are most likely derived from the Variscan accretionary complex exposed in the Anarak-Jandaq areas further northwest. This result underlines the importance of a major block boundary identified as the Chapedony fault, which is in extension of a fault previously proposed. (3) Two stages of Cimmerian events are visible in our data set from Cretaceous and Paleogene sandstones, a cluster around 170 Ma and at ca. 205 Ma. These clusters suggest a two-stage Cimmerian evolution of the largely amphibolite-grade metamorphic Posht-e-Badam and Boneh Shurow complexes. (4) The youngest micas in Paleogene conglomerates have an age of ca. 100 Ma and are most likely derived from the base of the Posht-e-Badam complex. No record of the uplifted Eocene Chapedony metamorphic core complex has been found in Eocene and Pliocene clastic rocks.

Syn-convergence extension in the southern Lhasa terrane: Evidence from late Cretaceous adakitic granodiorite and coeval gabbroic-dioritic dykes

NASA Astrophysics Data System (ADS)

Ma, Xuxuan; Xu, Zhiqin; Meert, Joseph G.

2017-10-01

Late Cretaceous (∼100-80 Ma) magmatism in the Gangdese magmatic belt plays a pivotal role in understanding the evolutionary history and tectonic regime of the southern Lhasa terrane. The geodynamic process for the formation of the early Late Cretaceous magmatism has long been an issue of hot debates. Here, petrology, geochronology and geochemistry of early Late Cretaceous granodiorite and coeval gabbroic-dioritic dykes in the Caina region, southern Lhasa, were investigated in an effort to ascertain their petrogenesis, age of intrusion, magma mixing and tectonic setting. Zircon U-Pb dating of granodiorite yields 206Pb/238U ages of 85.8 ± 1.7 and 86.4 ± 1.1 Ma, whilst that of the E-W trending dykes yields ages of 82.7 ± 2.6 and 83.5 ± 3.5 Ma. Within error, the crystallization ages of the dykes and the granodiorite are indistinguishable. Field observations and mineralogical microstructures are suggestive of a magma mixing process during the formation of the dykes and the granodiorite. The granodiorite exhibits geochemical features that are in agreement with those of subduction-related high-SiO2 adakites. The granodiorite and dykes have relatively constant εNd(t) values of +2.2 to +4.9 and initial 87Sr/86Sr ratios (0.7045-0.7047). These similar characteristics are herein interpreted as an evolutionary series from the dykes to granodiorite, consistent with magma mixing process. Ti-in-zircon thermometer and Al-in-hornblende barometer indicate that the granodiorite and the dioritic dyke crystallized at temperatures of ca. 750 and 800 °C, depths of ca. 6-10 and 5-9 km, respectively. Taking into account the synchronous magmatic rocks in the Gangdese Belt and the coeval rifted basin within the Lhasa terrane, the granodiorite and dykes reveal an early Late Cretaceous syn-convergence extensional regime in the southern Lhasa terrane, triggered by slab rollback of the Neotethyan oceanic lithosphere.

3D Architecture and evolution of the Po Plain-Northern Adriatic Foreland basin during Plio-Pleistocene time

NASA Astrophysics Data System (ADS)

Amadori, Chiara; Toscani, Giovanni; Ghielmi, Manlio; Maesano, Francesco Emanuele; D'Ambrogi, Chiara; Lombardi, Stefano; Milanesi, Riccardo; Panara, Yuri; Di Giulio, Andrea

2017-04-01

The Pliocene-Pleistocene tectonic and sedimentary evolution of the eastern Po Plain and northern Adriatic Foreland Basin (PPAF) (extended ca. 35,000 km2) was the consequence of severe Northern Apennine compressional activity and climate-driven eustatic changes. According with the 2D seismic interpretation, facies analysis and sequence stratigraphy approach by Ghielmi et al. (2013 and references therein), these tectono-eustatic phases generated six basin-scale unconformities referred as Base Pliocene (PL1), Intra-Zanclean (PL2), Intra-Piacenzian (PL3), Gelasian (PL4), Base Calabrian (PS1) and Late Calabrian (PS2). We present a basin-wide detailed 3D model of the PPAF region, derived from the interpretation of these unconformities in a dense network of seismic lines (ca. 6,000 km) correlated with more than 200 well stratigraphies (courtesy of ENI E&P). The initial 3D time-model has been time-to-depth converted using the 3D velocity model created with Vel-IO 3D, a tool for 3D depth conversions and then validated and integrated with depth domain dataset from bibliography and well log. Resultant isobath and isopach maps are produced to inspect step-by-step the basin paleogeographic evolution; it occurred through alternating stages of simple and fragmented foredeeps. Changes in the basin geometry through time, from the inner sector located in the Emilia-Romagna Apennines to the outermost region (Veneto and northern Adriatic Sea), were marked by repeated phases of outward migration of two large deep depocenters located in front of Emilia arcs on the west, and in front of Ferrara-Romagna thrusts on the east. During late Pliocene-early Pleistocene, the inner side of the Emilia-Romagna arcs evolved into an elongated deep thrust-top basin due to a strong foredeep fragmentation then, an overall tectono-stratigraphic analysis shows also a decreasing trend of tectonic intensity of the Northern Apennine since Pleistocene until present.

Late Cenozoic thermochronology and exhumation history of central Anatolia: Implications for the timing and nature of transition from collision to escape tectonics

NASA Astrophysics Data System (ADS)

Thomson, S. N.; Lefebvre, C.; Umhoefer, P. J.; Darin, M. H.; Whitney, D.; Teyssier, C. P.

2016-12-01

The central part of the Anatolian microplate in Turkey forms a complex tectonic zone situated between ongoing convergence of the Arabian and Eurasian plates to the east, and lateral escape of the Anatolian microplate as a rigid block to the west facilitated by two major strike-slip faults (the North and East Anatolian fault zones) that transitions westward into an extensional tectonic regime in western Turkey and the Aegean Sea related to subduction retreat. However, the geodynamic processes behind the transition from collision to escape, and the timing and nature of this transition, are complex and remain poorly understood. To gain a better understanding of the timing and nature of this transition, including the debated timing of ca. 35-20 Ma onset of collision between Arabia and Eurasia, we have undertaken a comprehensive low-temperature thermochronologic study in central Turkey to provide a record of exhumation patterns. We have collected over 150 samples, focused on the Central Anatolian Crystalline Complex (CACC), the Central Anatolian fault zone (CAFZ - proposed as a major lithosphere-scale structure that may also be related to onset of tectonic escape), and Eocene to Neogene sedimentary basins. Results include 113 apatite fission track (FT) ages (62 bedrock ages and 51 detrital ages), 26 detrital zircon FT ages, 218 apatite (U-Th)/He (He) ages from 84 mostly bedrock samples, and 15 zircon He ages from 6 bedrock samples. Our most significant new finding is identification of an early Miocene (ca. 22-15 Ma) phase of rapid cooling seen in the CACC. These cooling ages are localized in the footwalls of several large high-angle NW-SE trending normal faults, and imply significant footwall uplift and exhumation at this time. This early Miocene exhumation is restricted to entirely west of the CAFZ, and supports this fault marking a major tectonic transition active at this time. East of the CAFZ, AFT ages in sedimentary rocks show Eocene and older detrital ages despite much higher elevations (up to 3000m) suggesting uplift of the fault block east of CAFZ occurred since the late Miocene. An earlier Eocene (40-35 Ma) phase of cooling and exhumation is identified in deformed Paleocene-Eocene sedimentary rocks either side of the CAFZ likely related to a regional episode of shortening during final closure of the inner Tauride suture.

Provenance analysis on detrital zircons from the back-arc Arivechi basin: Implications for the Upper Cretaceous tectonic evolution of northern Sonora and southern Arizona

NASA Astrophysics Data System (ADS)

Rodríguez-Castañeda, José Luis; Ortega-Rivera, Amabel; Roldán-Quintana, Jaime; Espinoza-Maldonado, Inocente Guadalupe

2018-07-01

In the Arivechi region of eastern Sonora, northwestern Mexico, mountainous exposures of Upper Cretaceous rocks that contain monoliths within coarse sedimentary debris are enigmatic, in a province of largely Late Cretaceous continental-margin arc rocks. The rocks sequence in the study area are grouped in two Upper Cretaceous units: the lower Cañada de Tarachi and the younger El Potrero Grande. Detrital zircons collected from three samples of the Cañada de Tarachi and El Potrero Grande units have been analyzed for U-Pb ages to constrain their provenance. These ages constrain the age of the exposed rocks and provide new insights into the geological evolution of eastern Sonora Cretaceous rocks. The detrital zircon age populations determined for the Cañada de Tarachi and El Potrero Grande units contain distinctive Precambrian, Paleozoic, and Mesozoic zircon ages that provide probable source areas which are discussed in detail constraining the tectonic evolution of the region. Comparison of these knew ages with published data suggests that the source terranes, that supplied zircons to the Arivechi basin, correlate with Proterozoic, Paleozoic and Mesozoic domains in southern California and Baja California, northern Sonora, southern Arizona and eastern Chihuahua. The provenance variation is vital to constrain the source of the Cretaceous rocks in eastern Sonora and support a better understanding of the Permo-Triassic Cordilleran Magmatic Arc in the southwestern North America.

Regulation of Blood Pressure by Targeting CaV1.2-Galectin-1 Protein Interaction.

PubMed

Hu, Zhenyu; Li, Guang; Wang, Jiong-Wei; Chong, Suet Yen; Yu, Dejie; Wang, Xiaoyuan; Soon, Jia Lin; Liang, Mui Cheng; Wong, Yuk Peng; Huang, Na; Colecraft, Henry M; Liao, Ping; Soong, Tuck Wah

2018-04-12

Background -L-type Ca V 1.2 channels play crucial roles in regulation of blood pressure. Galectin-1 (Gal-1), has been reported to bind to the I-II loop of Ca V 1.2 channels to reduce their current density. However, the mechanistic understanding for the down-regulation of Ca V 1.2 channels by Gal-1, and whether Gal-1 plays a direct role in blood pressure regulation remain unclear. Methods - In vitro experiments involving co-IP, western blot, patch-clamp recordings, immunohistochemistry and pressure myography were used to evaluate the molecular mechanisms by which Gal-1 down-regulates Ca V 1.2 channel in transfected HEK 293 cells, smooth muscle cells, arteries from Lgasl1 -/- mice, rat and human patients. In vivo experiments involving delivery of Tat-e9c peptide and AAV5-Gal-1 into rats were performed to investigate the effect of targeting Ca V 1.2-Gal-1 interaction on blood pressure monitored by tail cuff or telemetry methods. Results -Our study reveals that Gal-1 is a key regulator for proteasomal degradation of Ca V 1.2 channels. Gal-1 competed allosterically with Ca V β subunit for binding to the I-II loop of Ca V 1.2 channel. This competitive disruption of Ca V β binding led to Ca V 1.2 degradation by exposing the channels to poly-ubiquitination. Notably, we demonstrated that the inverse relationship of reduced Gal-1 and increased Ca V 1.2 protein levels in arteries was associated with hypertension in hypertensive rats and patients, and Gal-1 deficiency induces higher blood pressure in mice due to up-regulated Ca V 1.2 protein level in arteries. To directly regulate blood pressure by targeting the Ca V 1.2-Gal-1 interaction, we administered Tat-e9c, a peptide that competed for binding of Gal-1, by a mini-osmotic pump and this specific disruption of Ca V 1.2-Gal-1 coupling increased smooth muscle Ca V 1.2 currents, induced larger arterial contraction and caused hypertension in rats. In contrasting experiments, over-expression of Gal-1 in smooth muscle by a single bolus of AAV5-Gal-1 significantly reduced blood pressure in spontaneously hypertensive rats. Conclusions -We have defined molecularly that Gal-1 promotes Ca V 1.2 degradation by replacing Ca V β and thereby exposing specific lysines for poly-ubiquitination, and by masking I-II loop ER export signals. This mechanistic understanding provided the basis for targeting Ca V 1.2-Gal-1 interaction to demonstrate clearly the modulatory role Gal-1 plays in regulating blood pressure, and offering a potential approach for therapeutic management of hypertension.

Seismic source parameters of the induced seismicity at The Geysers geothermal area, California, by a generalized inversion approach

NASA Astrophysics Data System (ADS)

Picozzi, Matteo; Oth, Adrien; Parolai, Stefano; Bindi, Dino; De Landro, Grazia; Amoroso, Ortensia

2017-04-01

The accurate determination of stress drop, seismic efficiency and how source parameters scale with earthquake size is an important for seismic hazard assessment of induced seismicity. We propose an improved non-parametric, data-driven strategy suitable for monitoring induced seismicity, which combines the generalized inversion technique together with genetic algorithms. In the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for the attenuation and site contributions. Then, the retrieved source spectra are inverted by a non-linear sensitivity-driven inversion scheme that allows accurate estimation of source parameters. We therefore investigate the earthquake source characteristics of 633 induced earthquakes (ML 2-4.5) recorded at The Geysers geothermal field (California) by a dense seismic network (i.e., 32 stations of the Lawrence Berkeley National Laboratory Geysers/Calpine surface seismic network, more than 17.000 velocity records). We find for most of the events a non-selfsimilar behavior, empirical source spectra that requires ωγ source model with γ > 2 to be well fitted and small radiation efficiency ηSW. All these findings suggest different dynamic rupture processes for smaller and larger earthquakes, and that the proportion of high frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with the earthquake size. Furthermore, we observe also two distinct families of events with peculiar source parameters that, in one case suggests the reactivation of deep structures linked to the regional tectonics, while in the other supports the idea of an important role of steeply dipping fault in the fluid pressure diffusion.

Depletion of intracellular calcium stores facilitates the influx of extracellular calcium in platelet derived growth factor stimulated A172 glioblastoma cells.

PubMed

Vereb, G; Szöllösi, J; Mátyus, L; Balázs, M; Hyun, W C; Feuerstein, B G

1996-05-01

Calcium signaling in non-excitable cells is the consequence of calcium release from intracellular stores, at times followed by entry of extracellular calcium through the plasma membrane. To study whether entry of calcium depends upon the level of saturation of intracellular stores, we measured calcium channel opening in the plasma membrane of single confluent A172 glioblastoma cells stimulated with platelet derived growth factor (PDGF) and/or bradykinin (BK). We monitored the entry of extracellular calcium by measuring manganese quenching of Indo-1 fluorescence. PDGF raised intracellular calcium concentration ([Ca2+]i) after a dose-dependent delay (tdel) and then opened calcium channels after a dose-independent delay (tch). At higher doses (> 3 nM), BK increased [Ca2+]i after a tdel approximately 0 s, and tch decreased inversely with both dose and peak [Ca2+]i. Experiments with thapsigargin (TG), BK, and PDGF indicated that BK and PDGF share intracellular Ca2+ pools that are sensitive to TG. When these stores were depleted by treatment with BK and intracellular BAPTA, tdel did not change, but tch fell to almost 0 s in PDGF stimulated cells, indicating that depletion of calcium stores affects calcium channel opening in the plasma membrane. Our data support the capacitative model for calcium channel opening and the steady-state model describing quantal Ca2+ release from intracellular stores.

Regular structural and compositional characteristics of Mercury predicted by the wave planetology

NASA Astrophysics Data System (ADS)

Kochemasov, G. G.

2012-09-01

In 1995 based on available at that time data for terrestrial planets a chart was built connecting them in respect of their chemistry, relief, and tectonic pattern. Mercury before the MESSENGER era has supplied very limited data on these characteristics. Thus, the chart was based mainly on understood regularit ies of changing cosmic parameters and Mercury as the nearest to Sun planet was assigned in advance as a dull low albedo variations, low relief, tectonically fine grained and with high Mg/Fe in the crust. To justify and explain by a wave interference action its fine tectonic granulation (πR/16) a radar image of its silhouette was used [1] (Fig. 1). The MESSENGER data later confirm this conclusion providing preliminary results of magnetic and gravity surveys [2, 3] (Fig. 2). The radar experiment shown very low alt itude variations (1-5 km), very smooth surface [4]. X-ray measurements shown very high Mg and low Fe abundances in the crust [5] that was quite a surprise to many planetary scientists but not for us, adherents of the wave planetology. The wave planetology [6-7 & others] states that any celestial body moving in non-circular but elliptical keplerian orbit with periodically changing acceleration suffers from a warping action of the inertia-gravity waves. In rotating bodies they have four ortho-and diagonal interfering directions producing uplifted, subsided, and neutral tectonic blocks. Their sizes depend on the warping wavelengths. The longest fundamental wave1 produces antipodean segments -hemis pheres (2πR-structure), its first overtone wave2 gives superposed tectonic sectors (πRstructure). On these already complicated pattern are superposed tectonic granules size of which is inversely proportional to orbital frequencies. Hence there is a regular row of tectonic granules s izes : Mercury π R/16, Venus πR/6, Earth πR/ 4, Mars πR/ 2, as teroids πR/1(coinc idence with the tectonic dichotomy).Thus, the mercurian tectonic granule size about 500 km across was predicted and now observed by the MESSENGER measurements: magnetic field variations, gravity anomalies, topographic uplifts [2- 4, 8]. As was shown earlier [9], there is a direct correlation between tectonic granule radii and relief ranges of terrestrial planets. The small relief range of Mercury (a few kms) corresponds with its fine tectonic granulation. Using petrography terms one may say that Mercury is "fine gra ined", Venus "mediu m grained", Ea rth "coars e grained", and Mars "pegmatoid". Thes e tectonic s tructures of rotating terrestrial planets force them to build subsided blocks of denser material than uplifted ones to keep more or less equilibrated their angular momenta. Higher relief range more significant must be density difference between risen and fallen tectonic blocks. In the row of terrestrial planets their s ubs ided "oceanic" areas become more Fe - rich (thus, denser) in direction from Mercury to Mars; their uplifted "highland" areas become mo re Si and alka lis -rich (thus, less dense) [10]. Mercury having the smallest tectonic granules and relief range has the smallest density diffe rence between "up" and "down" blocks and Mg -rich magmat ic lithologies in both [10, Fig. 3]. That is why Mercury has so dull appearance contrary to Mars with very high albedo difference between fallen north and risen south. In full agreement with the above regularity is an important conclusion of [11] about a regular rising K/Th in crusts from Mercury to Mars. To this one could add our earlier observation on decreasing atmospheric masses in the s ame direction due to diminis hing "wave s haking" - "sweeping out" volatiles fro m the solid bodies (the warping waves become larger and less frequent). Ratio of radiogenic to primordial argon in atmospheres regularly increases outwards: Venus 1, Earth 300, Mars 3000 [12]. Mercury shows very pronounced traces of very intensive degassing (numerous pits [13], contracting features). Surprising high sulfur content in X-ray measurements of Mercury should be cons idered as "tails " of intens ive degassing left on surface as fumaroles deposits. Thus one might conclude that its atmosphere, now lost, due to very intensive degassing could have been rather significant. One important structural peculiarity of rotating globular planetary bodies is their tendency to destroy tropical zones with the larger angular momentum to diminish it and to add some mass to extra-tropics to increase their angular momentum [14]. With this in mind one should interpret Xray data showing some increase of Fe content in Mg-rich rocks of the higher latitudes of Mercury [15]. The additional Fe instead of Mg increases rock density. In conclusion one should say that Mercury is the regular continuation of the terrestrial planets wave row with predictable characteristics.

Calcium alters monoamine oxidase-A parameters in human cerebellar and rat glial C6 cell extracts: possible influence by distinct signalling pathways.

PubMed

Cao, Xia; Li, Xin-Min; Mousseau, Darrell D

2009-07-31

Calcium (Ca(2+)) is known to augment monoamine oxidase-A (MAO-A) activity in cell cultures as well as in brain extracts from several species. This association between Ca(2+) and MAO-A could contribute to their respective roles in cytotoxicity. However, the effect of Ca(2+) on MAO-A function in human brain has as yet to be examined as does the contribution of specific signalling cascades. We examined the effects of Ca(2+) on MAO-A activity and on [(3)H]Ro 41-1049 binding to MAO-A in human cerebellar extracts, and compared this to its effects on MAO-A activity in glial C6 cells following the targeting of signalling pathways using specific chemical inhibitors. Ca(2+) enhances MAO-A activity as well as the association of [(3)H]Ro 41-1049 to MAO-A in human cerebellar extracts. The screening of neuronal and glial cell cultures reveals that MAO-A activity does not always correlate with the expression of either mao-A mRNA or MAO-A protein. Inhibition of the individual PI3K/Akt, ERK and p38(MAPK) signalling pathways in glial C6 cells all augment basal MAO-A activity. Inhibition of the p38(MAPK) pathway also augments Ca(2+)-sensitive MAO-A activity. We also observe the inverse relation between p38(MAPK) activation and MAO-A function in C6 cultures grown to full confluence. The Ca(2+)-sensitive component to MAO-A activity is present in human brain and in vitro studies link it to the p38(MAPK) pathway. This means of influencing MAO-A function could explain its role in pathologies as diverse as neurodegeneration and cancers.

Topological insulators double perovskites: A2TePoO6 (A = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Lee, Po-Han; Zhou, Jian; Pi, Shu-Ting; Wang, Yin-Kuo

2017-12-01

Based on first-principle calculations and direct density functional theory calculations of surface bands, we predict a new class of three-dimensional (3D) Z2 topological insulators (TIs) with larger bulk bandgaps up to 0.4 eV in double perovskite materials A2TePoO6 (A = Ca, Sr, and Ba). The larger nontrivial gaps are induced by the symmetry-protected band contact along with band inversion occurring in the absence of spin-orbit coupling (SOC) making the SOC more effective than conventional TIs. The proposed materials are chemically inert and more robust to surface perturbations due to its intrinsic protection layer. This study provides the double perovskite material as a rich platform to design new TI-based electronic devices.

Optical magnetoelectric effect at CaRuO3-CaMnO3 interfaces as a polar ferromagnet

NASA Astrophysics Data System (ADS)

Yamada, Hiroyuki; Sato, H.; Akoh, H.; Kida, N.; Arima, T.; Kawasaki, M.; Tokura, Y.

2008-02-01

A correlated electron interface between paramagnetic CaRuO3 and antiferromagnetic CaMnO3 has been characterized with optical magnetoelectric (OME) effect as an interface-selective probe for spin and charge states. To detect the OME effect, i.e., nonreciprocal directional dichroism for visible or near-infrared light, we have constructed a "tricolor" superlattice with artificially broken inversion symmetry by stacking CaRuO3, CaMnO3, and CaTiO3, and patterned a grating structure with 4μm period on the superlattice. The observed intensity modulation (0.3% at 50K) in the Bragg diffraction verifies a charge transfer and concomitant ferromagnetism at the CaRuO3-CaMnO3 interface.

Orebody geometry, fluid and metal sources of the Omitiomire Cu deposit in the Ekuja Dome of the Damara Belt in Namibia

NASA Astrophysics Data System (ADS)

Kitt, Shawn; Kisters, Alexander; Vennemann, Torsten; Steven, Nick

2018-02-01

The Omitiomire Cu deposit (resource of 137 Mt at 0.54% Cu) in the Ekuja Dome of the Damara Belt in Namibia is hosted by an anastomosing, low-angle Pan-African (ca. 520 Ma) shear zone system developed around an older (ca. 1100-1060 Ma), late Mesoproterozoic intrusive breccia between a suite of mafic rocks (originally lava flows) and later tonalitic gneisses. High-grade ore shoots preferentially formed along contacts between tectonically interleaved biotite-epidote-quartz-chalcocite schists and felsic gneisses, and are directly related to an increase in the number and cumulative thickness of thin, contact-parallel mineralized shear zones. Alteration and mineralization are associated with elevated concentrations of K2O, Cr, Rb, S, and Cu and a loss of Na2O, CaO, and MgO. Oxygen isotope fractionation for quartz-biotite, quartz-feldspar, and quartz-amphibole mineral pairs support equilibrium temperatures of between 500 and 650 °C during the fluid/rock interaction. Mineral separates from amphibole-biotite gneisses and mineralized schists have similar ranges in δ18O values of about 1.2 to 2 ‰ relative to VSMOW. Coexisting minerals are arranged in an order of increasing δ18O values from biotite, to epidote, amphibole, and quartz, suggesting that the Omitiomire Shear Zone was a rock-dominated system. Similarly, H-isotope results for mineral separates from biotite-epidote schists and amphibole gneisses do not show any reversals for D/H fractionations, with δD values of between -48 and -82 ‰, typical of metamorphic-magmatic rocks. The homogeneous and low δ34S values (-6.1 to -4.7 ‰ CDT) are compatible with a local redistribution of sulfur from magmatic rocks and interaction with sulfur derived from metamorphic fluids of metasedimentary origin. The relatively low fluid/rock ratios and elevated Cu values (>1500 ppm) from unaltered amphibolite point to a local redistribution of an earlier (late Mesoproterozoic) Keweenaw-type Cu mineralization into later Pan-African shear zones during the exhumation of the Ekuja Dome. The timing, polyphase evolution, and tectonic setting of the Omitiomire deposit show remarkable similarities with the large Cu deposits of the Domes Region in the adjoining Lufilian Arc of northern Zambia. This suggests the presence of a much larger, regionally significant Cu province extending from central Namibia, through northern Botswana, and into Zambia.

Velocity Structure of the Iran Region Using Seismic and Gravity Observations

NASA Astrophysics Data System (ADS)

Syracuse, E. M.; Maceira, M.; Phillips, W. S.; Begnaud, M. L.; Nippress, S. E. J.; Bergman, E.; Zhang, H.

2015-12-01

We present a 3D Vp and Vs model of Iran generated using a joint inversion of body wave travel times, Rayleigh wave dispersion curves, and high-wavenumber filtered Bouguer gravity observations. Our work has two main goals: 1) To better understand the tectonics of a prominent example of continental collision, and 2) To assess the improvements in earthquake location possible as a result of joint inversion. The body wave dataset is mainly derived from previous work on location calibration and includes the first-arrival P and S phases of 2500 earthquakes whose initial locations qualify as GT25 or better. The surface wave dataset consists of Rayleigh wave group velocity measurements for regional earthquakes, which are inverted for a suite of period-dependent Rayleigh wave velocity maps prior to inclusion in the joint inversion for body wave velocities. We use gravity anomalies derived from the global gravity model EGM2008. To avoid mapping broad, possibly dynamic features in the gravity field intovariations in density and body wave velocity, we apply a high-pass wavenumber filter to the gravity measurements. We use a simple, approximate relationship between density and velocity so that the three datasets may be combined in a single inversion. The final optimized 3D Vp and Vs model allows us to explore how multi-parameter tomography addresses crustal heterogeneities in areas of limited coverage and improves travel time predictions. We compare earthquake locations from our models to independent locations obtained from InSAR analysis to assess the improvement in locations derived in a joint-inversion model in comparison to those derived in a more traditional body-wave-only velocity model.

Reconstruction of the strain pattern in the Somma-Vesuvius area: field and remote sensing analyses

NASA Astrophysics Data System (ADS)

D'Assisi Tramparulo, Francesco; Bisson, Marina; Isaia, Roberto; Tadini, Alessandro; Vitale, Stefano

2016-04-01

Keywords: Somma-Vesuvio, structural analysis, volcano-tectonics. This study present a detailed structural analysis of the Somma-Vesuvio (SV) volcanic complex that couples field data about faults, fractures and dykes with the analysis of lineaments identified from high-resolution (1m) DTM deriving from LiDAR data. Field data were collected within the SV caldera,in some quarries along the volcano flanks, and in few outcrops along the carbonate reliefs bounding the southern sector of the Campania plain. A total of 8,500 orientation data have been analyzed through rose diagrams and inversion methods while a total of more than 4,000 lineaments were identified after the analyses of multiple hill shades obtained by applying different pseudo-illuminations (from NW, NE, SE and SW) and appropriate filters to the original DTM. Results indicate a complex interaction between volcanic (local) and tectonic (regional) stress fields. The preliminary analysis of lineaments indicate that most of them are radial with respect to the center of the caldera, however a "tectonic" component is present, mainly represented by the NNE-SSW, ENE-WSW and the well-known Apenninic (NW-SE) direction.

An ArcGIS approach to include tectonic structures in point data regionalization.

PubMed

Darsow, Andreas; Schafmeister, Maria-Theresia; Hofmann, Thilo

2009-01-01

Point data derived from drilling logs must often be regionalized. However, aquifers may show discontinuous surface structures, such as the offset of an aquitard caused by tectonic faults. One main challenge has been to incorporate these structures into the regionalization process of point data. We combined ordinary kriging and inverse distance weighted (IDW) interpolation to account for neotectonic structures in the regionalization process. The study area chosen to test this approach is the largest porous aquifer in Austria. It consists of three basins formed by neotectonic events and delimited by steep faults with a vertical offset of the aquitard up to 70 m within very short distances. First, ordinary kriging was used to incorporate the characteristic spatial variability of the aquitard location by means of a variogram. The tectonic faults could be included into the regionalization process by using breaklines with buffer zones. All data points inside the buffer were deleted. Last, IDW was performed, resulting in an aquitard map representing the discontinuous surface structures. This approach enables one to account for such surfaces using the standard software package ArcGIS; therefore, it could be adopted in many practical applications.

Mesozoic evolution of northeast African shelf margin, Libya and Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aadland, R.K.; Schamel, S.

1989-03-01

The present tectonic features of the northeast African shelf margin between the Nile delta and the Gulf of Sirte are products of (1) precursory late Paleozoic basement arches, (2) early Mesozoic rifting and plate separation, and (3) Late Cretaceous structural inversion. The 250 km-wide and highly differentiated Mesozoic passive margin in the Western Desert region of Egypt is developed above a broad northwest-trending Late Carboniferous basement arch. In northeastern Libya, in contrast, the passive margin is restricted to just the northernmost Cyrenaica platform, where subsidence was extremely rapid in the Jurassic and Early Cretaceous. The boundary between the Western Desertmore » basin and the Cyrenaica platform is controlled by the western flank of the basement arch. In the middle Cretaceous (100-90 Ma), subsidence accelerated over large areas of the Western desert, further enhancing a pattern of east-west-trending subbasins. This phase of rapid subsidence was abruptly ended about 80 Ma by the onset of structural inversion that uplifted the northern Cyrenaica shelf margin and further differentiated the Western Desert subbasin along a northeasterly trend.« less

Abnormalities in Dynamic Brain Activity Caused by Mild Traumatic Brain Injury Are Partially Rescued by the Cannabinoid Type-2 Receptor Inverse Agonist SMM-189

PubMed Central

McAfee, Samuel S.; Guley, Natalie M.; Del Mar, Nobel; Bu, Wei; Heldt, Scott A.; Honig, Marcia G.; Moore, Bob M.

2017-01-01

Abstract Mild traumatic brain injury (mTBI) can cause severe long-term cognitive and emotional deficits, including impaired memory, depression, and persevering fear, but the neuropathological basis of these deficits is uncertain. As medial prefrontal cortex (mPFC) and hippocampus play important roles in memory and emotion, we used multi-site, multi-electrode recordings of oscillatory neuronal activity in local field potentials (LFPs) in awake, head-fixed mice to determine if the functioning of these regions was abnormal after mTBI, using a closed-skull focal cranial blast model. We evaluated mPFC, hippocampus CA1, and primary somatosensory/visual cortical areas (S1/V1). Although mTBI did not alter the power of oscillations, it did cause increased coherence of θ (4-10 Hz) and β (10-30 Hz) oscillations within mPFC and S1/V1, reduced CA1 sharp-wave ripple (SWR)-evoked LFP activity in mPFC, downshifted SWR frequencies in CA1, and enhanced θ-γ phase-amplitude coupling (PAC) within mPFC. These abnormalities might be linked to the impaired memory, depression, and persevering fear seen after mTBI. Treatment with the cannabinoid type-2 (CB2) receptor inverse agonist SMM-189 has been shown to mitigate functional deficits and neuronal injury after mTBI in mice. We found that SMM-189 also reversed most of the observed neurophysiological abnormalities. This neurophysiological rescue is likely to stem from the previously reported reduction in neuron loss and/or the preservation of neuronal function and connectivity resulting from SMM-189 treatment, which appears to stem from the biasing of microglia from the proinflammatory M1 state to the prohealing M2 state by SMM-189. PMID:28828401

Abnormalities in Dynamic Brain Activity Caused by Mild Traumatic Brain Injury Are Partially Rescued by the Cannabinoid Type-2 Receptor Inverse Agonist SMM-189.

PubMed

Liu, Yu; McAfee, Samuel S; Guley, Natalie M; Del Mar, Nobel; Bu, Wei; Heldt, Scott A; Honig, Marcia G; Moore, Bob M; Reiner, Anton; Heck, Detlef H

2017-01-01

Mild traumatic brain injury (mTBI) can cause severe long-term cognitive and emotional deficits, including impaired memory, depression, and persevering fear, but the neuropathological basis of these deficits is uncertain. As medial prefrontal cortex (mPFC) and hippocampus play important roles in memory and emotion, we used multi-site, multi-electrode recordings of oscillatory neuronal activity in local field potentials (LFPs) in awake, head-fixed mice to determine if the functioning of these regions was abnormal after mTBI, using a closed-skull focal cranial blast model. We evaluated mPFC, hippocampus CA1, and primary somatosensory/visual cortical areas (S1/V1). Although mTBI did not alter the power of oscillations, it did cause increased coherence of θ (4-10 Hz) and β (10-30 Hz) oscillations within mPFC and S1/V1, reduced CA1 sharp-wave ripple (SWR)-evoked LFP activity in mPFC, downshifted SWR frequencies in CA1, and enhanced θ-γ phase-amplitude coupling (PAC) within mPFC. These abnormalities might be linked to the impaired memory, depression, and persevering fear seen after mTBI. Treatment with the cannabinoid type-2 (CB2) receptor inverse agonist SMM-189 has been shown to mitigate functional deficits and neuronal injury after mTBI in mice. We found that SMM-189 also reversed most of the observed neurophysiological abnormalities. This neurophysiological rescue is likely to stem from the previously reported reduction in neuron loss and/or the preservation of neuronal function and connectivity resulting from SMM-189 treatment, which appears to stem from the biasing of microglia from the proinflammatory M1 state to the prohealing M2 state by SMM-189.

Calsequestrin content and SERCA determine normal and maximal Ca2+ storage levels in sarcoplasmic reticulum of fast- and slow-twitch fibres of rat.

PubMed

Murphy, Robyn M; Larkins, Noni T; Mollica, Janelle P; Beard, Nicole A; Lamb, Graham D

2009-01-15

Whilst calsequestrin (CSQ) is widely recognized as the primary Ca2+ buffer in the sarcoplasmic reticulum (SR) in skeletal muscle fibres, its total buffering capacity and importance have come into question. This study quantified the absolute amount of CSQ isoform 1 (CSQ1, the primary isoform) present in rat extensor digitorum longus (EDL) and soleus fibres, and related this to their endogenous and maximal SR Ca2+ content. Using Western blotting, the entire constituents of minute samples of muscle homogenates or segments of individual muscle fibres were compared with known amounts of purified CSQ1. The fidelity of the analysis was proven by examining the relative signal intensity when mixing muscle samples and purified CSQ1. The CSQ1 contents of EDL fibres, almost exclusively type II fibres, and soleus type I fibres [SOL (I)] were, respectively, 36 +/- 2 and 10 +/- 1 micromol (l fibre volume)(-1), quantitatively accounting for the maximal SR Ca2+ content of each. Soleus type II [SOL (II)] fibres (approximately 20% of soleus fibres) had an intermediate amount of CSQ1. Every SOL (I) fibre examined also contained some CSQ isoform 2 (CSQ2), which was absent in every EDL and other type II fibre except for trace amounts in one case. Every EDL and other type II fibre had a high density of SERCA1, the fast-twitch muscle sarco(endo)plasmic reticulum Ca2+-ATPase isoform, whereas there was virtually no SERCA1 in any SOL (I) fibre. Maximal SR Ca2+ content measured in skinned fibres increased with CSQ1 content, and the ratio of endogenous to maximal Ca2+ content was inversely correlated with CSQ1 content. The relative SR Ca2+ content that could be maintained in resting cytoplasmic conditions was found to be much lower in EDL fibres than in SOL (I) fibres (approximately 20 versus >60%). Leakage of Ca2+ from the SR in EDL fibres could be substantially reduced with a SR Ca2+ pump blocker and increased by adding creatine to buffer cytoplasmic [ADP] at a higher level, both results indicating that at least part of the Ca2+ leakage occurred through SERCA. It is concluded that CSQ1 plays an important role in EDL muscle fibres by providing a large total pool of releasable Ca2+ in the SR whilst maintaining free [Ca2+] in the SR at sufficiently low levels that Ca2+ leakage through the high density of SERCA1 pumps does not metabolically compromise muscle function.

Effect of exchangeable cation concentration on sorption and desorption of dissolved organic carbon in saline soils.

PubMed

Setia, Raj; Rengasamy, Pichu; Marschner, Petra

2013-11-01

Sorption is a very important factor in stabilization of dissolved organic carbon (DOC) in soils and thus C sequestration. Saline soils have significant potential for C sequestration but little is known about the effect of type and concentration of cations on sorption and release of DOC in salt-affected soils. To close this knowledge gap, three batch sorption and desorption experiments were conducted using soils treated with solutions either low or high in salinity. In Experiment 1, salinity was developed with either NaCl or CaCl2 to obtain an electrical conductivity (EC) in a 1:5 soil: water extract (EC1:5) of 2 and 4 dS m(-1). In Experiments 2 and 3, NaCl and CaCl2 were added in various proportions (between 25 and 100%) to obtain an EC1:5 of 0.5 and 4 dS m(-1), respectively. At EC1:5 of 4 dS m(-1), the sorption of DOC (derived from wheat straw) was high even at a low proportion of added Ca(2+) and did not change with proportion of Ca added, but at EC1:5 of 0.5 dS m(-1) increasing proportion of Ca(2+) added increased DOC sorption. This can be explained by the differences in exchangeable Ca(2+) at the two salinity levels. At EC1:5 of 4 dS m(-1), the exchangeable Ca(2+) concentration did not increase beyond a proportion of 25% Ca(2+), whereas it increased with increasing Ca(2+) proportion in the treatments at EC1:5 of 0.5 dS m(-1). The DOC sorption was lowest with a proportion of 100% as Na(+). When Ca(2+) was added, DOC sorption was highest, but least was desorbed (with deionised water), thus sorption and desorption of added DOC were inversely related. The results of this study suggest that DOC sorption in salt-affected soils is mainly controlled by the levels of exchangeable Ca(2+) irrespective of the Ca(2+) concentration in the soil solution which has implications on carbon stabilization in salt-affected soils. Copyright © 2013 Elsevier B.V. All rights reserved.

Ocean alkalinity and the Cretaceous/Tertiary boundary

NASA Technical Reports Server (NTRS)

Caldeira, K. G.; Rampino, Michael R.

1988-01-01

A biogeochemical cycle model resolving ocean carbon and alkalinity content is applied to the Maestrichtian and Danian. The model computes oceanic concentrations and distributions of Ca(2+), Mg(2+), and Sigma-CO2. From these values an atmospheric pCO2 value is calculated, which is used to estimate rates of terrestrial weathering of calcite, dolomite, and calcium and magnesium silicates. Metamorphism of carbonate rocks and the subsequent outgassing of CO2 to the atmosphere are parameterized in terms of carbonate rock reservoir sizes, total land area, and a measure of overall tectonic activity, the sea-floor generation rate. The ocean carbon reservoir computed by the model is used with Deep Sea Drilling Project (DSDP) C-13 data to estimate organic detrital fluxes under a variety of ocean mixing rate assumptions. Using Redfield ratios, the biogenic detrital flux estimate is used to partition the ocean carbon and alkalinity reservoirs between the mixed layer and deep ocean. The calcite flux estimate and carbonate ion concentrations are used to determine the rate of biologically mediated CaCO3 titration. Oceanic productivity was severely limited for approximately 500 kyr following the K/T boundary resulting in significant increases in total ocean alkalinity. As productivity returned to the ocean, excess carbon and alkalinity was removed from the ocean as CaCO3. Model runs indicate that this resulted in a transient imbalance in the other direction. Ocean chemistry returned to near-equilibrium by about 64 mybp.

Fluvial archives, a valuable record of vertical crustal deformation

NASA Astrophysics Data System (ADS)

Demoulin, A.; Mather, A.; Whittaker, A.

2017-06-01

The study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms, but also for identifying the nature of crustal deformation and its history. In recent decades, geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens. Here, we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions (the effects of horizontal deformation are not addressed). Channel long profiles have received considerable attention in the literature, and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives, before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady-state characteristics. Then, we review the literature dealing with the transient response of rivers to tectonic perturbation, through the production of knickpoints propagating through the drainage network. Inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories. Finally, we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes. As well as the erosional imprint of tectonic forcing, sedimentary deposits, such as fluvial terrace staircases, are also considered as a classical component of tectonic geomorphology. We show that these studies have recently benefited from rapid advances in dating techniques, allowing more reliable reconstruction of incision histories and estimation of incision rates. The combination of progress in the understanding of transient river profiles and larger, more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation, i.e., extrapolation of local data to entire profiles. Finally, planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation. Examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the (dis)equilibrium state of drainage systems across regional drainage divides.

Geometry and kinematics of Majiatan Fold-and-thrust Belt, Western Ordos Basin: implication for Tectonic Evolution of North-South Tectonic Belt

NASA Astrophysics Data System (ADS)

He, D.

2017-12-01

The Helan-Chuandian North-South Tectonic Belt crossed the central Chinese mainland. It is a boundary of geological, geophysical, and geographic system of Chinese continent tectonics from shallow to deep, and a key zone for tectonic and geomorphologic inversion during Mesozoic to Cenozoic. It is superimposed by the southeastward and northeastward propagation of Qinghai-Tibet Plateau in late Cenozoic. It is thus the critical division for West and East China since Mesozoic. The Majiatan fold-and-thrust belt (MFTB), locating at the central part of HCNSTB and the western margin of Ordos Basin, is formed by the tectonic evolution of the Helan-Liupanshan Mountains. Based on the newly-acquired high-resolution seismic profiles, deep boreholes, and surface geology, the paper discusses the geometry, kinematics, and geodynamic evolution of MFTB. With the Upper Carboniferous coal measures and the pre-Sinian ductile zone as the detachments, MFTB is a multi-level detached thrust system. The thrusting was mainly during latest Jurassic to Late Cretaceous, breaking-forward in the foreland, and resulting in a shortening rate of 25-29%. By structural restoration, this area underwent extension in Middle Proterozoic to Paleozoic, which can be divided into three phases of rifting such as Middle to Late Proterozoic, Cambiran to Ordovician, and Caboniferous to early Permian. It underwent compression since Late Triassic, including such periods as Latest Triassic, Late Jurassic to early Cretaceous, Late Cretaceous to early Paleogene, and Pliocene to Quaternary, with the largest shortening around Late Jurassic to early Cretaceous period (i.e. the mid-Yanshanian movement by the local name). However, trans-extension since Eocene around the Ordos Basin got rise to the formation the Yingchuan, Hetao, and Weihe grabens. It is concluded that MFTB is the leading edge of the intra-continental Helan orogenic belt, and formed by multi-phase breaking-forward thrusting during Late Jurassic to Cretaceous. During Cenozoic, MFTB is moderately modified by the northeastward compression due to the NE propagation of Qinghai-Tibet Plateau, and distinctly superimposed by the Yingchuan half-graben. North-South Tectonic Belt underwent a full cycle from extension during Middle Proterozoic to Paleozoic to compression since late Triassic.

3D Modeling of Iran and Surrounding Areas From Simultaneous Inversion of Multiple Geophysical Datasets

DTIC Science & Technology

2010-09-01

which are primarily sensitive to upper crustal structures, are difficult to measure and especially true in tectonically and geologically complex areas...slice through the model (compare Figure 6 and Figure 9). The fit to the receiver function is not perfect and the spread of the slower deep crustal ...Although the final fit is certainly not perfect, note the improvement in timing of the main crustal conversion and reverberation (vertical lines) from the

Stress state reconstruction and tectonic evolution of the northern slope of the Baikit anteclise, Siberian Craton, based on 3D seismic data

NASA Astrophysics Data System (ADS)

Moskalenko, A. N.; Khudoley, A. K.; Khusnitdinov, R. R.

2017-05-01

In this work, we consider application of an original method for determining the indicators of the tectonic stress fields in the northern Baikit anteclise based on 3D seismic data for further reconstruction of the stress state parameters when analyzing structural maps of seismic horizons and corresponded faults. The stress state parameters are determined by the orientations of the main stress axes and shape of the stress ellipsoid. To calculate the stress state parameters from data on the spatial orientations of faults and slip vectors, we used the algorithms from quasiprimary stress computation methods and cataclastic analysis, implemented in the software products FaultKinWin and StressGeol, respectively. The results of this work show that kinematic characteristics of faults regularly change toward the top of succession and that the stress state parameters are characterized by different values of the Lode-Nadai coefficient. Faults are presented as strike-slip faults with normal or reverse component of displacement. Three stages of formation of the faults are revealed: (1) partial inversion of ancient normal faults, (2) the most intense stage with the predominance of thrust and strike-slip faults at north-northeast orientation of an axis of the main compression, and (3) strike-slip faults at the west-northwest orientation of an axis of the main compression. The second and third stages are pre-Vendian in age and correlate to tectonic events that took place during the evolution of the active southwestern margin of the Siberian Craton.

Development and evaluation of modified envelope correlation method for deep tectonic tremor

NASA Astrophysics Data System (ADS)

Mizuno, N.; Ide, S.

2017-12-01

We develop a new location method for deep tectonic tremors, as an improvement of widely used envelope correlation method, and applied it to construct a tremor catalog in western Japan. Using the cross-correlation functions as objective functions and weighting components of data by the inverse of error variances, the envelope cross-correlation method is redefined as a maximum likelihood method. This method is also capable of multiple source detection, because when several events occur almost simultaneously, they appear as local maxima of likelihood.The average of weighted cross-correlation functions, defined as ACC, is a nonlinear function whose variable is a position of deep tectonic tremor. The optimization method has two steps. First, we fix the source depth to 30 km and use a grid search with 0.2 degree intervals to find the maxima of ACC, which are candidate event locations. Then, using each of the candidate locations as initial values, we apply a gradient method to determine horizontal and vertical components of a hypocenter. Sometimes, several source locations are determined in a time window of 5 minutes. We estimate the resolution, which is defined as a distance of sources to be detected separately by the location method, is about 100 km. The validity of this estimation is confirmed by a numerical test using synthetic waveforms. Applying to continuous seismograms in western Japan for over 10 years, the new method detected 27% more tremors than a previous method, owing to the multiple detection and improvement of accuracy by appropriate weighting scheme.

3-D inversion of complex magnetotelluric data from an Archean-Proterozoic terrain in northeastern São Francisco Craton, Brazil

NASA Astrophysics Data System (ADS)

Bologna, Mauricio S.; Egbert, Gary D.; Padilha, Antonio L.; Pádua, Marcelo B.; Vitorello, Ícaro

2017-09-01

We present a magnetotelluric (MT) study in the northeastern part of the São Francisco Craton that encompasses an Archean-Proterozoic terrain, the Serrinha Block, breached by a rift basin developed mostly in Early Cretaceous times during the opening of the South Atlantic Ocean. Even though the MT sites are regularly spaced, the profiles have different orientations from one another, making the data distribution over the area highly uneven and therefore non-ideal for 3-D modeling. However, the data set is very complex, with dimensionality analysis indicating prevalence of 3-D geoelectric structure. Results from 3-D inversion are evaluated for robustness and potentiality for yielding tectonic information. At upper crustal depths, the resulting 3-D model is coherent with surface geology, whereas at mid and lower crustal depths more cryptic structures are revealed, likely of Palaeoproterozoic age. The most striking features in the model are several strong (∼1 Ωṡm) crustal conductors beneath the central part of the Serrinha Block, which we attribute to a Palaeoproterozoic oceanic plate subduction and arc-continent collision event involving the Rio Itapicuru Greenstone Belt and the basement of the Serrinha Block. The west-dipping geometry of these conductors provides a constraint on subduction polarity and gives support to tectonic evolutionary models proposing that the Rio Itapicuru Belt was formed in an island arc environment.

Characterization of transpressive deformation in shear zones of the Archean North Caribou greenstone belt (NW Superior Province) and the relationship with regional metamorphism

NASA Astrophysics Data System (ADS)

Gagnon, Émilie; Schneider, David A.; Kalbfleisch, Tash; Habler, Gerlinde; Biczok, John

2016-12-01

The 2.7-3.0 Ga North Caribou greenstone belt (NCGB), host to the Musselwhite BIF-hosted gold deposit, possesses abundant shear zones on its northern margins, which appear to have formed under amphibolite facies conditions. Protracted deformation and regional metamorphism are coeval with widespread magmatism and accretion events during crustal amalgamation of the Western Superior Province, and are responsible for folding the ore-hosting BIF and channeling fluids. The importance of shear zones in behaving as conduits for fluids during the tectonic evolution of the NCGB is not well known and their relationship with metamorphism is equivocal, yet higher-grade, syn- to post-tectonic metamorphic minerals seem to correlate with loci of higher strain. Structural analyses support oblique transpressive collision that produced steeply-dipping planar and shallowly-plunging linear fabrics with dominant dextral kinematics, that trend broadly parallel to the doubly arcuate shape of the belt. Electron backscatter diffraction analyses were conducted on strategic samples across one shear zone in order to characterize crustal conditions during transpressive deformation. The Dinnick Lake shear zone cuts through mafic metavolcanics and at its core is an L-tectonite granite composed of recrystallized quartz. Whole rock geochemistry shows little variation in Ca, Na, Mg and K (often used as indicators of hydrothermal alteration) from surrounding less deformed units, suggesting deformation in a dry environment. Microstructural analysis indicates subgrain rotation recrystallization and deformation by prism a- and c-slip in quartz, as well as aligned hornblende that suggest deformation temperatures above 500 °C. Quartz in mafic rocks along the margins of the shear zone also exhibits a basal a-slip component, indicating a slight decrease in strain or temperature. Although the NCGB exhibits some first-order evidence of vertical tectonism (dome and keel geometries), the dominant strain record within shear zones is that of horizontal (oblique transpressive) displacement. This is in agreement with other greenstone belts in the Western Superior Province where vertical tectonism and horizontal tectonism were coeval. Table A1. Whole rock geochemistry of basalts. Table A2. Whole rock geochemistry of granites. Table B.1. Parameters and conditions of machine during EBSD data collection. Table D1. Table of corresponding probability and critical d values of the K-S test. Fig. E1. Feldspar pole figures. Fig. E2. Hornblende pole figures. Fig. F1. Grain boundary misorientation histograms of feldspars. Fig. F2. Grain boundary misorientation histograms of hornblende.

Evolution and modulation of intracellular calcium release during long-lasting, depleting depolarization in mouse muscle

PubMed Central

Royer, Leandro; Pouvreau, Sandrine; Ríos, Eduardo

2008-01-01

Intracellular calcium signals regulate multiple cellular functions. They depend on release of Ca2+ from cellular stores into the cytosol, a process that in many types of cells appears to be tightly controlled by changes in [Ca2+] within the store. In contrast with cardiac muscle, where depletion of Ca2+ in the sarcoplasmic reticulum is a crucial determinant of termination of Ca2+ release, in skeletal muscle there is no agreement regarding the sign, or even the existence of an effect of SR Ca2+ level on Ca2+ release. To address this issue we measured Ca2+ transients in mouse flexor digitorum brevis (FDB) skeletal muscle fibres under voltage clamp, using confocal microscopy and the Ca2+ monitor rhod-2. The evolution of Ca2+ release flux was quantified during long-lasting depolarizations that reduced severely the Ca2+ content of the SR. As in all previous determinations in mammals and non-mammals, release flux consisted of an early peak, relaxing to a lower level from which it continued to decay more slowly. Decay of flux in this second stage, which has been attributed largely to depletion of SR Ca2+, was studied in detail. A simple depletion mechanism without change in release permeability predicts an exponential decay with time. In contrast, flux decreased non-exponentially, to a finite, measurable level that could be maintained for the longest pulses applied (1.8 s). An algorithm on the flux record allowed us to define a quantitative index, the normalized flux rate of change (NFRC), which was shown to be proportional to the ratio of release permeability P and inversely proportional to Ca2+ buffering power B of the SR, thus quantifying the ‘evacuability’ or ability of the SR to empty its content. When P and B were constant, flux then decayed exponentially, and NFRC was equal to the exponential rate constant. Instead, in most cases NFRC increased during the pulse, from a minimum reached immediately after the early peak in flux, to a time between 200 and 250 ms, when the index was no longer defined. NFRC increased by 111% on average (in 27 images from 18 cells), reaching 300% in some cases. The increase may reflect an increase in P, a decrease in B, or both. On experimental and theoretical grounds, both changes are to be expected upon SR depletion. A variable evacuability helps maintain a constant Ca2+ output under conditions of diminishing store Ca2+ load. PMID:18687715

Magmatism and crustal extension: Constraining activation of the ductile shearing along the Gediz detachment, Menderes Massif (western Turkey)

NASA Astrophysics Data System (ADS)

Rossetti, Federico; Asti, Riccardo; Faccenna, Claudio; Gerdes, Axel; Lucci, Federico; Theye, Thomas

2017-06-01

The Menderes Massif of western Turkey is a key area to study feedback relationships between magma generation/emplacement and activation of extensional detachment tectonics. Here, we present new textural analysis and in situ U-(Th)-Pb titanite dating from selected samples collected in the transition from the undeformed to the mylonitized zones of the Salihli granodiorite at the footwall of the Neogene, ductile-to-brittle, top-to-the-NNE Gediz-Alaşheir (GDF) detachment fault. Ductile shearing was accompanied by the fluid-mediated sub-solidus transformation of the granodiorite to orthogneiss, which occurred at shallower crustal levels and temperatures compatible with the upper greenschist-to-amphibolite facies metamorphic conditions (530-580 °C and P < 2 GPa). The syn-tectonic metamorphic overgrowth of REE-poor titanite on pristine REE-rich igneous titanite offers the possibility to constrain the timing of magma crystallisation and solid-state shearing at the footwall of the Gediz detachment. The common Pb corrected 206Pb/238U (206Pb*/238U) ages and the REE re-distribution in titanite that spatially correlates with the Th/U zoning suggests that titanite predominantly preserve open-system ages during fluid-assisted syn-tectonic re-crystallisation in the transition from magma crystallization and emplacement (at 16-17 Ma) to the syn-tectonic, solid-state shearing (at 14-15 Ma). A minimum time lapse of ca. 1-2 Ma is then inferred between the crustal emplacement of the Salihli granodiorite and nucleation of the ductile extensional shearing along the Gediz detachment. The reconstruction of the cooling history of the Salihli granodiorite documents a punctuated evolution dominated by two episodes of rapid cooling, between 14 Ma and 12 Ma ( 100 °C/Ma) and between 3 and 2 Ma ( 105 °C/Ma). We relate the first episode to nucleation and development of post-emplacement of ductile shearing along the GDF and the second to brittle high-angle faulting, respectively. Our dataset suggests that in the Menderes Massif the activation of ductile extension was a consequence, rather than the cause, of magma emplacement in the extending crust.

Focal mechanisms of recent earthquakes in the Southern Korean Peninsula

NASA Astrophysics Data System (ADS)

Park, Jong-Chan; Kim, Woohan; Chung, Tae Woong; Baag, Chang-Eob; Ree, Jin-Han

2007-06-01

We evaluate the stress field in and around the southern Korean Peninsula with focal mechanism solutions, using the data collected from 71 earthquakes (ML = 1.9-5.2) between 1999 and 2004. For this, the hypocentres were relocated and well-constrained fault plane solutions were obtained from the data set of 1270 clear P-wave polarities and 46 SH/P amplitude ratios. The focal mechanism solutions indicate that the prevailing faulting types in South Korea are strike-slip-dominant-oblique-slip faultings with minor reverse-slip component. The maximum principal stresses (σ1) estimated from fault-slip inversion analysis of the focal mechanism solutions show a similar orientation with E-W trend (269° -275°) and low-angle plunge (10° -25°) for all tectonic provinces in South Korea, consistent with the E-W trending maximum horizontal stress (σHmax) of the Amurian microplate reported from in situ stress measurements and earthquake focal mechanisms. The directions of the intermediate (σ2) and minimum (σ3) principal stresses of the Gyeongsang Basin are, however, about 90 deg off from those of the other tectonic provinces on a common σ2-σ3 plane, suggesting a permutation of σ2 and σ3. Our results incorporated with those from the kinematic studies of the Quaternary faults imply that NNW- to NE-striking faults (dextral strike-slip or oblique-slip with a reverse-slip component) are highly likely to generate earthquakes in South Korea.

Water-rock interaction and geochemistry of groundwater from the Ain Azel aquifer, Algeria.

PubMed

Belkhiri, Lazhar; Mouni, Lotfi; Tiri, Ammar

2012-02-01

Hydrochemical, multivariate statistical, and inverse geochemical modeling techniques were used to investigate the hydrochemical evolution within the Ain Azel aquifer, Algeria. Cluster analysis based on major ion contents defined 3 main chemical water types, reflecting different hydrochemical processes. The first group water, group 1, has low salinity (mean EC = 735 μS/cm). The second group waters are classified as Cl-HCO(3)-alkaline earth type. The third group is made up of water samples, the cation composition of which is dominated by Ca and Mg with anion composition varying from dominantly Cl to dominantly HCO(3) plus SO(4). The varifactors obtained from R-mode FA indicate that the parameters responsible for groundwater quality variations are mainly related to the presence and dissolution of some carbonate, silicate, and evaporite minerals in the aquifer. Inverse geochemical modeling along groundwater flow paths indicates the dominant processes are the consumption of CO(2), the dissolution of dolomite, gypsum, and halite, along with the precipitation of calcite, Ca-montmorillonite, illite, kaolinite, and quartz. © Springer Science+Business Media B.V. 2011

Structure and evolution of a rocksalt-mudrock-tectonite: The haselgebirge in the Northern Calcareous Alps.

PubMed

Leitner, Christoph; Neubauer, Franz; Urai, János L; Schoenherr, Johannes

2011-05-01

The Northern Calcareous Alps are part of the Eastern Alps in Austria and Germany. The Mesozoic units of this fold-and-thrust belt were detached, thrusted and stacked along the evaporitic Haselgebirge Formation. Exposed in salt mines, rocksalt and mudrock form a two component tectonite: The rock type "haselgebirge" consists of 10-70 wt % halite with silt- to gravel- or block-sized components within a halite matrix, and the "kerngebirge" with >70 wt % halite. All rock types studied are fault rocks. By use of a temperature-independent subgrain size piezometer, the paleo-differential stress of halite was calculated at ca. 2.5 MPa in Altaussee and ca. 4.5 MPa in Berchtesgaden. Including data from a grain-size piezometer, temperatures were estimated at ca. 150 ± 20 °C and 110 ± 10 °C. This implies very high strain rates, which are about 10 -10 -10 -9  s -1 . During the tectonic movement, the halite deformed, recrystallized, and crystallized as veins in mudrock fractures. We interpret high overpressure of the pore fluid to have significantly contributed to fracturing of the mudrock.

An ostracode based paleolimnologic and paleohydrologic history of Death Valley: 200 to 0 ka

USGS Publications Warehouse

Forester, R.M.; Lowenstein, T.K.; Spencer, R.J.

2005-01-01

Death Valley, a complex tectonic and hydrologic basin, was cored from its lowest surface elevation to a depth of 186 m. The sediments range from bedded primary halite to black muds. Continental ostracodes found in the black muds indicate that those sediments were deposited in a variety of hydrologic settings ranging from deep, relatively fresh water to shallow saline lakes to spring discharge supported wetlands. The alkaline-enriched, calcium-depleted paleolake waters indicate extrabasinal streamflow and basin-margin spring discharge. The alkaline-depleted, calcium-enriched paleowetland waters indicate intrabasinal spring discharge. During Marine Isotope Stage 6 (MIS 6, ca. 180-140 ka) the hydrologic settings were highly variable, implying that complex relations existed between climate and basin hydrology. Termination II (MIS 6 to MIS 5E) was a complex multicyclic sequence of paleoenvironments, implying that climates oscillated between high and low effective moisture. MIS 4 (ca. 73-61 ka) was a spring discharge supported wetland complex. During MIS 2 (ca. 20-12 ka) the hydrologic settings were variable, although they are not fully understood because some black muds deposited during that time were lost during coring. ?? 2005 Geological Society of America.

Capillary instability of periodic polymer structures: Influence of viscosity, substrate confinement and local curvature

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Ding, Yifu

2015-03-01

NMR spectrum and spin-lattice relaxation time(T1) of CaF2 thin film samples deposited on a silicon cantilever tip were obtained by magnetic resonance force microscopy(MRFM). Thickness of the thin films were 50nm and 150nm. In order to measure T1, a cyclic adiabatic inversion method was used with periodic phase inversion. A comparison of the bulk and two thin films showed that T1 becomes shorter as the film thickness decreases. To make the comparison as accurate as possible, all three samples were loaded onto different beams of a multi-cantilever array and measured in the same experimental conditions such as temperature and magnetic field.

The Origin of Tholeiitic and Calc-Alkaline Trends in Arc Magmas

NASA Astrophysics Data System (ADS)

Luffi, P. I.; Lee, C.

2012-12-01

It has long been recognized that tholeiitic (TH, high-Fe/Mg) and calc-alkaline (CA, low-Fe/Mg) magmatic series define the two most important igneous differentiation trends shaping Earth's crust. While oceanic crust formation at mid-ocean ridges is typically confined to a TH trend, arc magmatism at convergent margins, considered to significantly contribute to continent formation, generates both TH and CA trends. Thus, the origin of these trends - a key issue to understanding how continental crust forms - is matter of ongoing debate. Prevalent factors thought to contribute to the TH-CA duality are: 1) redox conditions (oxygen fugacity, fO2) and H2O contents in magmas, which control the onset and abundance of high-Fe/Mg oxide mineral fractionation; 2) crystallization depths that regulate the fractionating solid assemblage and thereby the solid/liquid Kd(Fe-Mg). Relying on an extensive geochemical dataset of modern arc volcanics and thermodynamic phase equilibria modeling, here we examine the validity and relative importance of these factors in arc petrogenesis. First, to discriminate igneous rocks more efficiently, we formulate an improved CA/TH index solely based on FeO-MgO systematics. We then confirm on a quantitative basis that, on regional scales, arcs formed on thick crust tend to be more calk-alkaline than those emplaced on thinner crust are, and show that the effect of fO2 on the CA/TH index in arc magmas is more significant than that of H2O. Importantly, we demonstrate that CA trends typical for continental arcs only form when crystal fractionation is accompanied by the assimilation of oxidized crustal components; in the absence of buffering oxidized assimilants fractionating magmas follow a TH trend more common in island arcs, irrespective of their H2O content and initial fO2 level. We find that high-pressure fractionation of amphibole and garnet in arc magmas occurs too late to have a significant influence on the CA/TH index; in addition, garnet-melt and amphibole-melt Kd(Fe-Mg) values may be too low to account for CA trends observed in thick continental arcs. Hence, depths of crystallization do not appear to influence the CA/TH index directly. We speculate that typical island arcs are dominantly tholeiitic because here crustal assimilation is inhibited and magma throughput is enhanced by extensional tectonic regimes. In contrast, the dominantly calc-alkaline nature of thicker continental arcs may be the consequence of efficient assimilation of oxidized crustal materials in a compressional environment restraining magma throughput.

Changes in Central Walker Lane Strain Accommodation near Bridgeport, California; as told by the Stanislaus Group

NASA Astrophysics Data System (ADS)

Carlson, C. W.; Pluhar, C. J.; Glen, J. M.; Farner, M. J.

2012-12-01

Accommodating ~20-25% of the dextral-motion between the Pacific and North American plates the Walker Lane is represented as an elongate, NW oriented, region of active tectonics positioned between the northwesterly-translating Sierra Nevada microplate and the east-west extension of the Basin and Range. This region of transtension is being variably accommodated on regional-scale systems of predominantly strike-slip faulting. At the western edge of the central Walker Lane (ca. 38°-39°N latitude) is a region of crustal-scale blocks bounded by wedge-shaped depositional-basins and normal-fault systems, here defined as the west-central Walker Lane (WCWL). Devoid of obvious strike-slip faulting, the presence of tectonic-block vertical-axis rotations in the WCWL represents unrecognized components of dextral-shearing and/or changes of strain-accommodation over time. We use paleomagnetic reference directions for Eureka Valley Tuff (EVT) members of the late Miocene Stanislaus Group as spatial and temporal markers for documentation of tectonic-block vertical-axis rotations near Bridgeport, CA. Study-site rotations revealed discrete rotational domains of mean vertical-axis rotation ranging from ~10°-30° with heterogeneous regional distribution. Additionally, the highest measured magnitudes of vertical-axis rotation (~50°-60° CW) define a 'Region of High Strain' that includes the wedge-shaped Bridgeport Valley (Basin). This study revealed previously-unrecognized tectonic rotation of reference direction sites from prior studies for two (By-Day and Upper) of the three members of the EVT, resulting in under-estimates of regional strain accommodation by these studies. Mean remanent directions and virtual geomagnetic poles utilized in our study yielded a recalculated reference direction for the By-Day member of: Dec.=353.2°; Inc.= 43.7°; α95=10.1, in agreement with new measurements in the stable Sierra Nevada. This recalculated direction confirmed the presence of previously unrecognized reference site rotations, and provided an additional reference direction for determining vertical-axis rotation magnitudes. We present a kinematic model based on mean rotation magnitudes of ~30° CW for the Sweetwater Mountains and Bodie Hills that accounts for rotational-strain accommodation of dextral shear in the WCWL since the late Miocene. This model considers rotational magnitudes, paleostrain indicators, edge-effects, and strain-accommodating structures of rotating crustal blocks to represent changes in regional strain accommodation over time. The results and models presented here elucidate the complicated and evolving nature of the WCWL, and further understanding of variations in strain accommodation for the Walker Lane.

Tectono-sedimentary analysis using the anisotropy of magnetic susceptibility: a study of the terrestrial and freshwater Neogene of the Orava Basin

NASA Astrophysics Data System (ADS)

Łoziński, Maciej; Ziółkowski, Piotr; Wysocka, Anna

2017-10-01

The Orava Basin is an intramontane depression filled with presumably fine-grained sediments deposited in river, floodplain, swamp and lake settings. The basin infilling constitutes a crucial record of the neoalpine evolution of the Inner/Outer Carpathian boundary area since the Neogene, when the Jurassic-Paleogene basement became consolidated, uplifted and eroded. The combination of sedimentological and structural studies with anisotropy of magnetic susceptibility (AMS) measurements provided an effective tool for recognition of terrestrial environments and deformations of the basin infilling. The lithofacies-oriented sampling and statistical approach to the large dataset of AMS specimens were utilized to define 12 AMS facies based on anisotropy degree (P) and shape (T). The AMS facies allowed a distinction of sedimentary facies ambiguous for classical methods, especially floodplain and lacustrine sediments, as well as revealing their various vulnerabilities to tectonic modification of AMS. A spatial analysis of facies showed that tuffites along with lacustrine and swamp deposits were generally restricted to marginal and southern parts of the basin. Significant deformations were noticed at basin margins and within two intrabasinal tectonic zones, which indicated the tectonic activity of the Pieniny Klippen Belt after the Middle Miocene. The large southern area of the basin recorded consistent N-NE trending compression during basin inversion. This regional tectonic rearrangement resulted in a partial removal of the southernmost basin deposits and shaped the basin's present-day extent.

Geologic and Seismologic Investigation

DTIC Science & Technology

1988-12-01

Descriptions, Hidden and Buchanan Dams 4 1.6.1 Hidden Dam 4 1.6.2 Buchanan Dam 5 2 TECTONIC SETTING 2.1 General 7 2.2 Cretaceous-Cenozoic Tectonic ...Activity 7 2.2.1 Cretaceous-Paleogene 8 2.2.2 Neogene 9 2.2.3 Late Cenozoic Tectonic Model 9 3 REGIONAL GEOLOGY 3.1 General 11 3.2 Geologic Units 11...detected by the imagery analysis which indicates there has been no tectonic movement from about 100,000 to 400,000 years ago to the present. The field

Slip slidin' away: A post-glacial environmental history of the Waipaoa River basin

NASA Astrophysics Data System (ADS)

Gomez, Basil; Rosser, Brenda J.

2018-04-01

The dramatic changes that occurred to the post-glacial landscape in the headwaters of the Waipaoa River basin are a consequence of perturbations about the equilibrium that exists between the rate of tectonic uplift and fluvial incision. At times when the amount of coarse sediment delivered to channels exceeds the capacity of streams to remove it, the channel bed rises at the rate of tectonic uplift. Once bedload overcapacity is replaced by undercapacity and the alluvial cover is depleted, streams reestablish contact with bedrock and recuperate the time lost to fluvial incision. The first major perturbation occurred during the final phase of the last glaciation (ca. 33-17.5 cal. ka), when aggradation was driven by a climate-forced variation in the relative supplies of sediment and water. We suggest that the subsequent transformation of channels in the headwaters of the Waipaoa River basin, from alluvial to bedrock, occurred as the atmospheric and oceanic circulation converged on their contemporary patterns ca. 12 cal. ka. A second major perturbation that continues to the present began ca. 1910-1912 CE, when a massive increase in sediment load was accompanied by a modest increase in water discharge after the native vegetation cover in the headwaters was replaced by pasture. The processes of terrace creation and incision are inherently unsteady, and in five interim cases incision was arrested by a transient increase in the thickness of the alluvial cover that was a response to climatic forcing. Events that disrupted the native vegetation cover in the headwaters also modulated patterns of sediment dispersal and accumulation in other parts of the fluvial system and caused rapid, storm-driven infilling of the Poverty Bay Flats. Tectonic subsidence dictates the course of the Waipaoa River across Poverty Bay Flats which, because the modern rate of floodplain construction by vertical accretion is rapid relative to the amount of destruction by lateral channel migration, has remained virtually unchanged for the past 100 years. During this time the channel assumed a narrower, deeper form that is in equilibrium with the contemporary supply of sediment and hydraulic regime.

Reaction enthalpy from the binding of multivalent cations to anionic polyelectrolytes in dilute solutions

NASA Astrophysics Data System (ADS)

Hansch, Markus; Kaub, Hans Peter; Deck, Sascha; Carl, Nico; Huber, Klaus

2018-03-01

Dilute solutions of sodium poly(styrene sulfonate) (NaPSS) in the presence of Al3+, Ca2+, and Ba2+ were analysed by means of isothermal titration calorimetry (ITC) in order to investigate the heat effect of bond formation between those cations and the anionic SO3- residues of NaPSS. The selection of the cations was guided by the solution behavior of the corresponding PSS salts from a preceding study [M. Hansch et al., J. Chem. Phys. 148(1), 014901 (2018)], where bonds between Ba2+ and anionic PSS showed an increasing solubility with decreasing temperature and Al3+ exhibited the inverse trend. Unlike to Al3+ and Ba2+, Ca2+ is expected to behave as a purely electrostatically interacting bivalent cation and was thus included in the present study. Results from ITC satisfactorily succeeded to explain the temperature-dependent solution behavior of the salts with Al3+ and Ba2+ and confirmed the non-specific behavior of Ca2+. Additional ITC experiments with salts of Ca2+ and Ba2+ and sodium poly(acrylate) complemented the results on PSS by data from a chemically different polyanion. Availability of these joint sets of polyanion-cation combinations not only offers the chance to identify common features and subtle differences in the solution behavior of polyelectrolytes in the presence of multi-valent cations but also points to a new class of responsive materials.

Oceanic Remnants In The Caribbean Plate: Origin And Loss Of Related LIPs.

NASA Astrophysics Data System (ADS)

Giunta, G.

2005-12-01

The modern Caribbean Plate is an independent lithospheric entity, occupying more than 4 Mkm2 and consisting of the remnants of little deformed Cretaceous oceanic plateau of the Colombia and Venezuela Basins (almost 1 Mkm2) and the Palaeozoic-Mesozoic Chortis continental block (about 700,000 km2), both bounded by deformed marginal belts. The northern (Guatemala and Greater Antilles) and the southern (northern Venezuela) plate margins are marked by collisional zones, whereas the western (Central America Isthmus) and the eastern (Lesser Antilles) margins are represented by convergent boundaries and their magmatic arcs, all involving ophiolitic terranes. The evolutionary history of the Caribbean Plate since the Jurassic-Early Cretaceous encompasses plume, accretionary, and collisional tectonics, the evidence of which has been recorded in the oceanic remnants of lost LIPs, as revealed in: i) the MORB to OIB thickened crust of the oceanic plateau, including its un-deformed or little deformed main portion, and scattered deformed tectonic units; ii) ophiolitic tectonic units of MORB affinity and the rock blocks in ophiolitic melanges; iii) intra-oceanic, supra subduction magmatic sequences with IAT and CA affinities. The Mesozoic oceanic LIPs, from which the remnants of the Caribbean Plate have been derived, have been poorly preserved during various episodes of the intra-oceanic convergence, either those related to the original proto-Caribbean oceanic realm or those connected with two eo-Caribbean stages of subduction. The trapped oceanic plateau of the Colombia and Venezuela Basins is likely to be an unknown portion of a bigger crustal element of a LIP, similar to the Ontong-Java plateau. The Jurassic-Early Cretaceous proto-Caribbean oceanic domain consists of oceanic crust generated at multiple spreading centres; during the Cretaceous, part of this crust was thickened to form an oceanic plateau with MORB and OIB affinities. At the same time, both South and North American continental margins, inferred to be close to the oceanic realm, were affected by rifting and within-plate tholeiitic magmatism (WPT); this interpretation supports a near mid-America original location of the "proto-Caribbean" LIP. The MORB magmatic sections and rock blocks in the ophiolitic melanges are interpreted as exhumed tectonic sheets of the normal proto-Caribbean oceanic lithosphere, or part of a back-arc crust, both deformed in the eo-Caribbean stages. The SSZ complexes, considered as Cordilleran-type deformed ophiolites, were derived from a LIP that experienced two superimposed eo-Caribbean stages of intra-oceanic subduction. The older (Mid-Cretaceous) stage involved the eastward subduction of the un-thickened proto-Caribbean lithosphere, resulting in IAT and CA magmatism accompanied by HP-LT metamorphism and melange formation. The second, Late Cretaceous stage involved a westward dipping intra-oceanic subduction, which generated tonalitic arc magmatism. The eastward wedging of the Caribbean Plateau between the North and South American plates progressively trapped remnants of the Colombia and Venezuela Basins between the Atlantic and Pacific subduction zones and their new volcanic arcs (Aves-Lesser Antilles and Central American Isthmus). Unlike the proto-Caribbean, it appears that this LIP did not involve the main continental margins, even though the northern and southern Caribbean borders experienced different evolutionary paths. It was largely lost by superimposed accretionary and collisional events producing the marginal belts of the Caribbean Plate; its evolution has been dominated by a strongly oblique tectonic regime, constraining seafloor spreading, subduction, crustal exhumation, emplacement, and dismembering processes.

Gondwanan/peri-Gondwanan origin for the Uchee terrane, Alabama and georgia: Carolina zone or Suwannee terrane(?) and its suture with Grenvillian basement of the Pine Mountain window

USGS Publications Warehouse

Steltenpohl, M.G.; Mueller, P.M.; Heatherington, A.L.; Hanley, T.B.; Wooden, J.L.

2008-01-01

The poorly known, suspect, Uchee terrane occupies a critical tectonic position with regard to how and when peri-Gondwanan (Carolina) and Gondwanan (Suwannee) terranes were sutured to Laurentia. It lies sandwiched between Laurentian(?) continental basement exposed in the Pine Mountain window and adjacent buried Gondwanan crust of the Suwannee terrane. The Uchee terrane has been proposed as both a septum of Piedmont rocks that once was continuous across the erosionally breached Pine Mountain window or part of the Carolina zone. To help resolve this issue, we conducted U-Pb (SHRIMP-RG) (sensitive high-resolution ion microprobe-reverse geometry) zircon studies and whole-rock isotopic analyses of principal metasedimentary and metaplutonic units. U-Pb ages for zircons from the Phenix City Gneiss suggest igneous crystallization at ca. 620 Ma, inheritance ca. 1000 to ca. 1700 Ma, and a ca. 300 Ma (Alleghanian) overprint recorded by zircon rims. Zircons from the metasedimentary/metavolcaniclastic Moffits Mill Schist yield bimodal dates at ca. 620 and 640 Ma. The 620 to 640 Ma dates make these rocks age-equivalent to the oldest parts of the Carolina slate belt (Virgilina and Savannah River) and strongly suggest a Gondwanan (Pan-African and/or Trans-Brasiliano) origin for the Uchee terrane. Alternatively, the Uchee terrane may be correlative with metamorphic basement of the Suwannee terrane. The ca. 300 Ma overgrowths on zircons are compatible with previously reported 295 to 288 Ma 40Ar/39Ar hornblende dates on Uchee terrane rocks, which were interpreted to indicate deep tectonic burial of the Uchee terrane contemporaneous with the Alleghanian orogeny recorded in the foreland. Temperature-time paths for the Uchee terrane are similar to that of the Pine Mountain terrane, indicating a minimum age of ca. 295 Ma for docking. In terms of tectono-metamorphic history of the Uchee terrane, it is important to note that no evidence for intermediate "Appalachian" dates (e.g, Acadian or Taconian) has been reported. This younger history, together with the ages of metaigneous rocks and evidence for pre-Grenville basement, suggests the Uchee terrane is likely of Gondwanan origin and may he related to Carolina zone terranes that accreted during the Alleghanian orogeny. ?? 2008 Geological Society of America.

A test of the hypothesis that oxalate secretion produces proximal tubule crystallization in primary hyperoxaluria type I

PubMed Central

Evan, Andrew P.; Coe, Fredric L.; Lingeman, James E.; Krambeck, Amy; Sommers, Andre; Phillips, Carrie L.; Milliner, Dawn

2013-01-01

The sequence of events by which primary hyperoxaluria type 1 (PH1) causes renal failure is unclear. We hypothesize that proximal tubule (PT) is vulnerable because oxalate secretion raises calcium oxalate (CaOx) supersaturation (SS) there, leading to crystal formation and cellular injury. We studied cortical and papillary biopsies from two PH1 patients with preserved renal function, and seven native kidneys removed from four patients at the time of transplant, after short-term (2) or longer term (2) dialysis. In these patients, and another five PH1 patients without renal failure, we calculated oxalate secretion, and estimated PT CaOx SS. Plasma oxalate was elevated in all PH1 patients and inverse to creatinine clearance. Renal secretion of oxalate was present in all PH1 but rare in controls. PT CaOx SS was >1 in all nonpyridoxine-responsive PH1 before transplant and most marked in patients who developed end stage renal disease (ESRD). PT from PH1 with preserved renal function had birefringent crystals, confirming the presence of CaOx SS, but had no evidence of cortical inflammation or scarring by histopathology or hyaluronan staining. PH1 with short ESRD showed CaOx deposition and hyaluronan staining particularly at the corticomedullary junction in distal PT while cortical collecting ducts were spared. Longer ESRD showed widespread cortical CaOx, and in both groups papillary tissue had marked intratubular CaOx deposits and fibrosis. CaOx SS in PT causes CaOx crystal formation, and CaOx deposition in distal PT appears to be associated with ESRD. Minimizing PT CaOx SS may be important for preserving renal function in PH1. PMID:24089413

Mapping Electrical Structures in the Jarud Basin, Northeast China through Magnetotelluric Sounding

NASA Astrophysics Data System (ADS)

Zhao, W.

2015-12-01

In recent years, China Geological Survey (CGS) has launched 3D geological mapping programs from regional to local scales. The project Deep geological survey at the periphery of the Songliao Basin funded by CGS was implemented from 2012 to 2014. Its main goals are to reveal the tectonic framework of the Jarud Basin (JB) as well as to identify the strata distribution of Permian Linxi Formation by integrating new electromagnetic data with existing geophysical and geological data since black mudstones in the Linxi Formation have shown the potential of shale gas. The study area covered dominantly with Cretaceous-Jurassic igneous rocks with exception of the southeast part is situated in Jarud Banner and Ar Horqin Banner, Inner Mongolia, China. It tectonically lies in the southern Great Khingan Range, western margin of the Songliao Basin, and north of Xar Moron Fault. Over the period of 2012 to 2014, a magnetotelluric survey was carried out at the JB. A total of 926 MT sites with nominal spacing 1 km was acquired in the effective frequency range of 0.01 Hz ~ 300 Hz on six NW and five NE profiles, covering area that exceeds 10, 000 km2. After dimensionality analysis and static shift removal, the nonlinear conjugate algorithm was used to conduct 2D inversion for TM and TE modes. The resistivity models underwent examination using sensitivity tests. The optimal resistivity models revealed numerous large faults, some of which constitute the boundaries of the JB, and modified the tectonic framework. Integrated with well logging and geological mapping data, the strata of Linxi Formation were identified and classified into three depressions: Depressions Arituguri, Gadasu and Wufen. Attention should be paid to Depression Gadasu with area of around 500 km2 since it contains reasonably thick conductive sediments exceeding 4 km in depth which are inferred to be black mudstones pertaining to shale gas.

Sheet intrusions and deformation of Piton des Neiges, and their implication for the volcano-tectonics of La Réunion

NASA Astrophysics Data System (ADS)

Chaput, Marie; Famin, Vincent; Michon, Laurent

2017-10-01

To understand the volcano-tectonic history of Piton des Neiges (the dormant volcano of La Réunion), we measured in the field the orientation of sheeted intrusions and deformation structures, and interpreted the two datasets separately with a paleostress inversion. Results show that the multiple proposed rift zones may be simplified into three trends: (1) a N30°E, 5 km wide linear rift zone running to the south of the edifice, active in the shield building (≥ 2.48-0.43 Ma) and terminal stages (190-22 ka); (2) a curved N110 to N160°E rift zone, widening from 5 km to 10 km toward the NW flank, essentially active during the early emerged shield building (≥ 1.3 Ma); and (3) two sill zones, ≤ 1 km thick in total, in the most internal parts of the volcano, active in the shield building and terminal stages. In parallel, deformation structures reveal that the tectonics of the edifice consisted in three end-member stress regimes sharing common stress axes: (1) NW-SE extension affecting in priority the south of the edifice near the N30°E rift zone; (2) NNE-SSW extension on the northern half of the volcano near the N110-160°E rift zone; (3) compression occurring near the sill zones, with a NE-SW or NW-SE maximum principal stress. These three stress regimes are spatially correlated and mechanically compatible with the injection trends. Combined together, our data show that the emerged Piton des Neiges underwent sector spreading delimited by perpendicular rift zones, as observed on Piton de la Fournaise (the active volcano of La Réunion). Analogue experiments attribute such sector spreading to brittle edifices built on a weaker substratum. We therefore conclude that La Réunion volcanoes are both brittle, as opposed to Hawaiian volcanoes or Mount Etna whose radial spreading is usually attributed to a ductile body within the edifices.

Reinterpretation of Paleoproterozoic accretionary boundaries of the north-central United States based on a new aeromagnetic-geologic compilation

USGS Publications Warehouse

Holm, D.K.; Anderson, R.; Boerboom, Terrence; Cannon, W.F.; Chandler, V.; Jirsa, M.; Miller, J.; Schneider, D.A.; Schulz, K.J.; Van Schmus, W. R.

2007-01-01

The Paleoproterozoic crust in the north-central U.S. represents intact juvenile terranes accreted to the rifted Archean Superior craton. A new tectonic province map, based on the interpretation of a new aeromagnetic compilation, published geologic maps, and recent geochronologic data, shows progressive accretion of juvenile arc terranes from ca. 1900-1600 Ma. Contrary to earlier models, geon 18 Penokean-interval crust is primarily confined to a ???2100 Ma tectonic embayment of the rifted Superior craton. The newly defined Spirit Lake tectonic zone, characterized by a sharp magnetic discontinuity that marks the southern limit of Archean and Penokean-interval rocks, is here interpreted to represent an eastern analog of the Cheyenne belt suture zone in southern Wyoming. South of this boundary, geon 17 Yavapai-interval rocks form the basement upon which 1750 Ma rhyolite and succeeding quartzite sequences were deposited. Substantial portions of the Penokean and Yavapai terranes were subsequently deformed during the 1650-1630 Ma Mazatzal orogeny. The northern boundary of the Mazatzal terrane is obscured by abundant 1470-1430 Ma "anorogenic" plutons that stitched the suture with the older Yavapai terrane rocks. These data reveal a progressive tectonic younging to the south as the Laurentian craton grew southward and stabilized during the Proterozoic. Late Mesoproterozoic rift magmatism produced pronounced geophysical anomalies, indicating strong, but localized crustal modification. In comparison to the western U.S., little tectonism has occurred here in the last 1 billion years, providing a uniquely preserved record of the Precambrian evolution of the continental U.S. lithosphere. ?? 2007 Elsevier B.V. All rights reserved.

The general description of major ion concentrations in groundwater of Latvia

NASA Astrophysics Data System (ADS)

Kalvāns, A.; Delina, A.

2012-04-01

Latvia is situated at the North central part of the Baltic sedimentary basin where the crystalline basement is found in depth between 0.6 to 2 km. Three large aquifer complexes with distinct chemical composition of groundwater are identified: the stagnant water exchange zone where Na-Ca-Cl brine is found; the slow water exchange zone where Na-Ca-Cl-SO4 brackish water is found and active water exchange zone where the freshwater resides. These are separated by distinct regional aquicludes. The composition of the Cl- dominated brines at the base of sedimentary basin is characterised by shift from Na+ towards Ca++ as dominant cation, partially associated with depth of the aquifer and the strength of the brine. The concentration of SO4-- here is inversely linked to the concentration of Ca++ and, according to geochemical modelling, often is close to the solubility limit of the gypsum. The major ion concentrations in the E and W part of the territory are rather different. Therefore two different initial sources of the formation brine were suggested. Alternatively the observations can be explained by different thermal histories of different parts of the basin, affecting the rate of albitization - exchange of the Na for Ca in the solution due to water-rock interaction. The groundwater composition in the slow exchange zone can be nicely explained by the mixing of freshwater and brine residing deeper in the presence of gypsum during some but no all stages of mixing. In some shallow parts of the zone still bound by the Narva regional aquiclude freshwater is found. The question is posted - could this be a paleogroundwater originating from the extensive continental glaciations that override the territory several times during the Pleistocene? Initial isotope studies presented elsewhere seems to give negative answer to this question. The active water exchange zone is characterised by fresh Ca-Mg-HCO3 water with exceptions in cases where gypsum are abundant in sedimentary rocks and sulphate ion prevails. The freshwater composition seems to be mostly controlled by three minerals - calcite, dolomite and gypsum. It is suggested that clay minerals can play a significant role in controlling the relative concentrations of cations, but this is not strictly proven jet. Well documented modern seawater intrusion induced by water abstraction is found in the territory of Liepāja city. The upwelling of slat water from below can be spotted across the territory as well. These zones are usually associated with tectonic faults, enabling the upwelling of salty water across regional aquicludes. Particularly prominent is the saltwater body in the vicinity of the Riga city. Three major rives are discharging in the sea there making it a natural confluence zone of groundwater as well. The intensive groundwater abstraction in the city probably enhanced the upwelling of saltwater here, but primary it is a natural phenomenon. The interesting question is if there is any paleogroundwater trapped in the active or slow water exchange zone of the sedimentary basin that could be distinguished from modern infiltration water due to particular isotope signal originating in the quaternary cold stages or chemical composition - remains of relict sea water or sedimentation water. This study is supported by the ESF project No. 2009/0212/1DP/1.1.1.2.0/09/APIA/VIAA/060.

Long-wavelength Magnetic and Gravity Anomaly Correlations of Africa and Europe

NASA Technical Reports Server (NTRS)

Vonfrese, R. R. B.; Hinze, W. J. (Principal Investigator); Olivier, R.

1984-01-01

Preliminary MAGSAT scalar magnetic anomaly data were compiled for comparison with long-wavelength-pass filtered free-air gravity anomalies and regional heat-flow and tectonic data. To facilitate the correlation analysis at satellite elevations over a spherical-Earth, equivalent point source inversion was used to differentially reduce the magnetic satellite anomalies to the radial pole at 350 km elevation, and to upward continue the first radial derivative of the free-air gravity anomalies. Correlation patterns between these regional geopotential anomaly fields are quantitatively established by moving window linear regression based on Poisson's theorem. Prominent correlations include direct correspondences for the Baltic Shield, where both anomalies are negative, and the central Mediterranean and Zaire Basin where both anomalies are positive. Inverse relationships are generally common over the Precambrian Shield in northwest Africa, the Basins and Shields in southern Africa, and the Alpine Orogenic Belt. Inverse correlations also presist over the North Sea Rifts, the Benue Rift, and more generally over the East African Rifts. The results of this quantitative correlation analysis support the general inverse relationships of gravity and magnetic anomalies observed for North American continental terrain which may be broadly related to magnetic crustal thickness variations.

Long-wavelength magnetic and gravity anomaly correlations on Africa and Europe

NASA Technical Reports Server (NTRS)

Vonfrese, R. R. B.; Olivier, R.; Hinze, W. J.

1985-01-01

Preliminary MAGSAT scalar magnetic anomaly data were compiled for comparison with long-wavelength-pass filtered free-air gravity anomalies and regional heat-flow and tectonic data. To facilitate the correlation analysis at satellite elevations over a spherical-Earth, equivalent point source inversion was used to differentially reduce the magnetic satellite anomalies to the radial pole at 350 km elevation, and to upward continue the first radial derivative of the free-air gravity anomalies. Correlation patterns between these regional geopotential anomaly fields are quantitatively established by moving window linear regression based on Poisson's theorem. Prominent correlations include direct correspondences for the Baltic shield, where both anomalies are negative, and the central Mediterranean and Zaire Basin where both anomalies are positive. Inverse relationships are generally common over the Precambrian Shield in northwest Africa, the Basins and Shields in southern Africa, and the Alpine Orogenic Belt. Inverse correlations also presist over the North Sea Rifts, the Benue Rift, and more generally over the East African Rifts. The results of this quantitative correlation analysis support the general inverse relationships of gravity and magnetic anomalies observed for North American continental terrain which may be broadly related to magnetic crustal thickness variations.

Sedimentary record of late Paleozoic to Recent tectonism in central Asia — analysis of subsurface data from the Turan and south Kazak domains

NASA Astrophysics Data System (ADS)

Thomas, J. C.; Cobbold, P. R.; Shein, V. S.; Le Douaran, S.

1999-11-01

The Turan and south Kazak domains (TSK) are in central Asia, between the Caspian Sea and the Tien Shan. The area is covered by sediments, deposited since the Late Permian during a series of tectonic events closely related to the history of two oceanic domains, Paleotethys and Neotethys. Sedimentary basins on the TSK therefore provide constraints on the tectonic development of the southern margin of Eurasia since the Late Permian. Our study is based on structure-contour maps and isopach maps of five key stratigraphic markers, of Late Permian to Tertiary age. Isopach maps help locate major faults and delimit sedimentary basins, providing information on vertical motions and, in some instances, horizontal motions. Subsidence associated with extension appears to have dominated the TSK, from the Late Permian to the Eocene. The extension may have been of back-arc type in southern Eurasia, next to the active margin, where the Paleotethys and Neotethys successively subducted toward the north. Here, sedimentary basins are both wide and deep (up to 15 km). During the Mesozoic, two compressional events of regional significance occurred in association with accretion of continental blocks at the southern margin of Eurasia. The first one, at the end of the Triassic, led to strong selective inversion of basins over the Turan domain. The second one, during the Late Jurassic-Early Cretaceous, had weaker effects. Since the Oligocene, following collision of both India and Arabia with Eurasia, inversion has become more generalized and compressional basins have formed on the TSK. Throughout the entire history of development of the TSK, from the Late Permian to the Tertiary, structures of Paleozoic and early Mesozoic age have exerted a strong control on sedimentation and especially on the location of depocenters. The south Kazak domain has registered little subsidence, in comparison with the Turan domain, where some basins have become very deep.

Building a Catalog of Time-Dependent Inversions for Cascadia ETS Events

NASA Astrophysics Data System (ADS)

Bartlow, N. M.; Williams, C. A.; Wallace, L. M.

2017-12-01

Episodic Tremor and Slip (ETS), composed of periodically occurring slow slip events accompanied by tectonic tremor, have been recognized in Cascadia since 1999. While the tremor has been continuously and automatically monitored for a few years (Wech et al., SRL, 2010; pnsn.org/tremor), the geodetically-derived slip has not been systematically monitored in the same way. Instead, numerous time-dependent and static inversions of the geodetic data have been performed for individual ETS events, with many events going unstudied. Careful study of, and monitoring of, ETS is important both to advance the scientific understanding of fault mechanics and to improve earthquake hazard forecasting in Cascadia. Here we present the results of initial efforts to standardize geodetic inversions of slow slip during Cascadia ETS. We use the Network Inversion Filter (NIF, Segall and Matthews,1997; McGuire and Segall, 2003; Miyazaki et al.,2006), applied evenly to an extended time period, to detect and catalog slow slip transients. Bartlow et al., 2014, conducted a similar study for the Hikurangi subduction zone, covering a 2.5 year period. Additionally, we generate Green's functions using the PyLith finite element code (Aagaard et al., 2013) to allow consideration of elastic property variations derived from a Cascadia-wide seismic velocity model (Stephenson, USGS pub., 2007). These Green's functions are then integrated to provide Green's functions compatible with the Network Inversion Filter. The use of heterogeneous elastic Green's functions allows for a more accurate estimation of slip amplitudes, both during individual ETS events and averaged over multiple events. This is useful for constraining the total slip budget in Cascadia, including whether ETS takes up the entire plate motion on the deeper extent of the plate interface where it occurs. The recent study of Williams and Wallace, GRL, 2015 demonstrated that the use heterogeneous elastic Green's Functions in inversions can make a significant difference in resulting slip distributions.

Modes of adaptation of peripheral neuroendocrine mechanisms of the sympatho-adrenal system to short-term stress as studied in two inbred rat strains.

PubMed

Gilad, G M; Jimerson, D C

1981-02-09

Alterations in mechanisms involved in catecholamine (CA) and corticosterone (B) regulation following short periods of stress have been investigated in two inbred rat strains: a strain more reactive to stress, Wistar-Kyoto (WK), and a less reactive strain, Brown-Norway (BN). Measurements after decapitation stress alone and after decapitation following different periods of immobilization stress, indicate that: (a) plasma CA levels immediately after severe stress (i.e. decapitation) are directly related to the behavioral reactivity of the two rat strains to stress but inversely related to adrenal gland size, their content of CA and biosynthetic enzymes, and to plasma levels of MHPG; (b) levels of B in adrenal glands and in plasma after stress are similar in both strains, in spite of different gland sizes; (c) CAT activity in presynaptic sympathetic terminals is directly related to plasma CA after short-term stress; and (d) liver COMT activity is directly related to plasma CA levels after stress, but inversely plasma levels of MHPG. The implications of the findings are discussed further in the text and lead to the conclusion that the BN strain represents a mode of a slower response to stressful stimuli than WK.

Architecture of ductile-type passive margins: Geological constraints from the inverted Cretaceous basin of the North-Pyrenean Zone (`Chaînons Béarnais', Western Pyrenees)

NASA Astrophysics Data System (ADS)

Corre, B.; Lagabrielle, Y.; Labaume, P.; Lahfid, A.; Boulvais, P.; Bergamini, G.; Fourcade, S.; Clerc, C. N.; Asti, R.

2017-12-01

Subcontinental lithospheric mantle rocks are exhumed at the foot of magma-poor distal passive margins as a response to extreme stretching of the continental crust. The North-Pyrenean Zone (NPZ) exposes remnants of such extremely stretched paleo-passive margin that represent field analogues to study the processes of continental crust thinning and mantle exhumation. The NPZ results from the inversion of basins opened between the Iberia and Europa plates during Albo-Cenomanian times. The Chaînons Béarnais belt displays a fold-and-thrust structure involving the Mesozoic sedimentary cover associated with peridotite bodies in tectonic contact with Paleozoic basement lenses of small size. Continental extension developed under hot thermal conditions, as demonstrated by the syn-metamorphic Cretaceous ductile deformation affecting both the crustal basement and the Mesozoic cover. In this study, we present structural and geochemical data providing constraints to reconstruct the evolution of this paleo-margin. Field work confirms that the Mesozoic cover is intimately associated with mantle rocks and thin tectonic lenses of middle crust. Micro-structural studies show that the greenschist facies ductile deformation in the crust produced a mylonitic foliation which is always parallel to the crust/mantle contact. The crust/mantle detachment fault is a major shear zone characterized by anastomosed shear bands. It also shows that the pre-rift cover was detached from its bedrock at the Keuper evaporites level and was welded to mantle rocks during their exhumation at the foot of the margin. We show that: (i) the boudinaged pre-rift sediments have undergone drastic syn-metamorphic thinning with the genesis of a S0/S1 foliation and, (ii) the Paleozoic basement has been ductilely deformed, into thin tectonic lenses that remained welded to the exhumed mantle rocks. The ductile behavior is related to the presence of a thick pre- and syn-rift cover acting as an efficient thermal blanket. This new geological data set highlights important characteristics of ductile-type hyper-extended passive margin. Finally, we stress that studying field analogues represents a major tool to better understand the mechanisms of crustal thinning associated with mantle exhumation and their structural inheritance during tectonic inversion.

Age and tectonic implications of Paleoproterozoic Deo Khe Granitoids within the Phan Si Pan Zone, Vietnam

NASA Astrophysics Data System (ADS)

Anh, Hoang Thi Hong; Hieu, Pham Trung; Tu, Vu Le; Son, La Mai; Choi, Sung Hi; Yu, Yongjae

2015-11-01

We report the first U-Pb zircon ages of 1855-1873 Ma for the Deo Khe Granitoids (DKG) in the Phan Si Pan Zone (PSPZ) of northern Vietnam. The DKG are medium-grained two-mica granitoids predominantly composed of quartz, K-feldspar, and muscovite. Trace element analyses indicate that the DKG are enriched in large ion lithophile elements but depleted in high field strength elements. Zircons from the granitoids have negative εHf(t) values ranging from -23.6 to -17.5. The magmatic zircons from the DKG have single-stage Hf model ages (TDM1) that range from 3.3 to 2.8 Ga and their εHf(t) data all plot well below the evolution trend of 2800 Ma average juvenile mantle. Observed Hf model ages are contemporaneous with the emplacement of 2.90-2.84 Ga tonalite-trondhjemite-granodiorite (TTG) gneiss observed in a nearby Ca Vinh Complex, suggesting that PSPZ in northern Vietnam is a product of partial melting of Archean crust. A sequence of similar tectonic events including initial emplacement of TTG protolith at 2.8-2.9 Ga, metamorphic development of TTG gneiss at 1.9-2.0 Ga, and magmatic activity at 1.8-2.0 Ga are now recognized both in northern Vietnam and Yangtze block which we interpret to indicate basement rocks in northern Vietnam are similar to those found along southern China.

A statistical assessment of seismic models of the U.S. continental crust using Bayesian inversion of ambient noise surface wave dispersion data

NASA Astrophysics Data System (ADS)

Olugboji, T. M.; Lekic, V.; McDonough, W.

2017-07-01

We present a new approach for evaluating existing crustal models using ambient noise data sets and its associated uncertainties. We use a transdimensional hierarchical Bayesian inversion approach to invert ambient noise surface wave phase dispersion maps for Love and Rayleigh waves using measurements obtained from Ekström (2014). Spatiospectral analysis shows that our results are comparable to a linear least squares inverse approach (except at higher harmonic degrees), but the procedure has additional advantages: (1) it yields an autoadaptive parameterization that follows Earth structure without making restricting assumptions on model resolution (regularization or damping) and data errors; (2) it can recover non-Gaussian phase velocity probability distributions while quantifying the sources of uncertainties in the data measurements and modeling procedure; and (3) it enables statistical assessments of different crustal models (e.g., CRUST1.0, LITHO1.0, and NACr14) using variable resolution residual and standard deviation maps estimated from the ensemble. These assessments show that in the stable old crust of the Archean, the misfits are statistically negligible, requiring no significant update to crustal models from the ambient noise data set. In other regions of the U.S., significant updates to regionalization and crustal structure are expected especially in the shallow sedimentary basins and the tectonically active regions, where the differences between model predictions and data are statistically significant.

Geology of the Orcopampa 30 minute quadrangle, southern Peru with special focus on the evolution of the Chinchon and Huayta calderas

NASA Astrophysics Data System (ADS)

Swanson, Kirk Edward

The 30 minute Orcopampa quadrangle, southern Peru, was a site of several episodes of Neogene volcanism, hydrothermal activity and precious-metal mineralization. Lavas of pyroxene andesite and associated silicic tuffs of the early Miocene Santa Rosa volcanics are the remnants of stratovolcanoes overlying an irregular erosional surface developed on a transgressive Mesozoic marine succession. Major ash-flow volcanism then resulted in the 20.1 Ma Manto Tuff and the associated Chinchon caldera. Deep dissection, locally >2 km, has exposed the steep caldera margin, slide blocks and related (19.9 Ma) dikes. Flows and domes of hornblende-biotite dacite comprising the Sarpane volcanics were erupted between about 18.5--19.5 Ma over much of the northern part of the quadrangle. Early Miocene rocks were folded during the Quechua I tectonic event, and related ENE-trending normal faults host the 17.8 Ma Ag-Au veins of the Orcopampa district. Eruption of the ca. 11.6 Ma tuffs of Cerro Huayta and Cerro Hospicio resulted in formation of the Huayta caldera, nested within the northern part of the Chinchon caldera. Caldera formation was associated with, and followed by, the eruption of intermediate lavas of Cerro Sahuarque ( ca. 11.4 Ma) and the emplacement of rhyolite domes. The adularia-sericite type Au-Ag veins of Mina Shila were formed along the southern margin of the Huayta caldera several million years after collapse. The 7.3 Ma tuff of Laguna Pariguanas, erupted from vents northeast of the Huayta caldera, appears to be deformed; however, the 6.2 Ma tuff of Umachulco postdates Quechua II/III tectonism. Flows and domes of the ca. 7.2 Ma andesite of Cerro Aseruta were emplaced within the Huayta caldera, and approximately contemporaneous lavas of silicic to intermediate composition were erupted in the northern part of the quadrangle. A large area of largely barren acid-sulfate alteration (Chuchanne) formed within the Huayta caldera shortly after the eruption of the andesite of Cerro Aseruta. Pliocene volcanic activity included the formation of the Cailloma caldera to the east and the Coropuna caldera southwest of the Orcopampa quadrangle. Lava flows, cinder cones and small shield volcanoes of intermediate composition of the Andagua volcanics were formed from late Pliocene to Holocene time.

Plate tectonic controls on atmospheric CO2 levels since the Triassic.

PubMed

Van Der Meer, Douwe G; Zeebe, Richard E; van Hinsbergen, Douwe J J; Sluijs, Appy; Spakman, Wim; Torsvik, Trond H

2014-03-25

Climate trends on timescales of 10s to 100s of millions of years are controlled by changes in solar luminosity, continent distribution, and atmosphere composition. Plate tectonics affect geography, but also atmosphere composition through volcanic degassing of CO2 at subduction zones and midocean ridges. So far, such degassing estimates were based on reconstructions of ocean floor production for the last 150 My and indirectly, through sea level inversion before 150 My. Here we quantitatively estimate CO2 degassing by reconstructing lithosphere subduction evolution, using recent advances in combining global plate reconstructions and present-day structure of the mantle. First, we estimate that since the Triassic (250-200 My) until the present, the total paleosubduction-zone length reached up to ∼200% of the present-day value. Comparing our subduction-zone lengths with previously reconstructed ocean-crust production rates over the past 140 My suggests average global subduction rates have been constant, ∼6 cm/y: Higher ocean-crust production is associated with longer total subduction length. We compute a strontium isotope record based on subduction-zone length, which agrees well with geological records supporting the validity of our approach: The total subduction-zone length is proportional to the summed arc and ridge volcanic CO2 production and thereby to global volcanic degassing at plate boundaries. We therefore use our degassing curve as input for the GEOCARBSULF model to estimate atmospheric CO2 levels since the Triassic. Our calculated CO2 levels for the mid Mesozoic differ from previous modeling results and are more consistent with available proxy data.

Plate tectonic controls on atmospheric CO2 levels since the Triassic

PubMed Central

Van Der Meer, Douwe G.; Zeebe, Richard E.; van Hinsbergen, Douwe J. J.; Sluijs, Appy; Spakman, Wim; Torsvik, Trond H.

2014-01-01

Climate trends on timescales of 10s to 100s of millions of years are controlled by changes in solar luminosity, continent distribution, and atmosphere composition. Plate tectonics affect geography, but also atmosphere composition through volcanic degassing of CO2 at subduction zones and midocean ridges. So far, such degassing estimates were based on reconstructions of ocean floor production for the last 150 My and indirectly, through sea level inversion before 150 My. Here we quantitatively estimate CO2 degassing by reconstructing lithosphere subduction evolution, using recent advances in combining global plate reconstructions and present-day structure of the mantle. First, we estimate that since the Triassic (250–200 My) until the present, the total paleosubduction-zone length reached up to ∼200% of the present-day value. Comparing our subduction-zone lengths with previously reconstructed ocean-crust production rates over the past 140 My suggests average global subduction rates have been constant, ∼6 cm/y: Higher ocean-crust production is associated with longer total subduction length. We compute a strontium isotope record based on subduction-zone length, which agrees well with geological records supporting the validity of our approach: The total subduction-zone length is proportional to the summed arc and ridge volcanic CO2 production and thereby to global volcanic degassing at plate boundaries. We therefore use our degassing curve as input for the GEOCARBSULF model to estimate atmospheric CO2 levels since the Triassic. Our calculated CO2 levels for the mid Mesozoic differ from previous modeling results and are more consistent with available proxy data. PMID:24616495

Cardiopulmonary Function, Exercise Capacity, and Echocardiography Finding of Pediatric Patients With Kawasaki Disease: An Observational Study.

PubMed

Tuan, Sheng-Hui; Li, Min-Hui; Hsu, Miao-Ju; Tsai, Yun-Jeng; Chen, Yin-Han; Liao, Tin-Yun; Lin, Ko-Long

2016-01-01

Coronary artery (CA) abnormalities influence exercise capacity (EC) of patients with Kawasaki disease (KD), and Z-score of CA is a well established method for detecting CA aneurysm. We studied the influence of KD on cardiopulmonary function and EC; meanwhile we analyzed echocardiographic findings of KD patients. We also assessed the correlation between CA Z-score and EC of KD patients to see if CA Z-score of KD patients could reflect EC during exercise.Sixty-three KD patients were recruited as KD group 1 from children (aged 5-18 y) who received transthoracic echocardiographic examinations and symptom-limited treadmill exercise test for regular follow-up of KD from January 2010 to October 2014 in 1 medical center. We then divided KD group 1 into KD group 2 (<5 y, n = 12) and KD group 3 (≥5 y, n = 51) according to time interval between KD onset to when patients received test. Control groups were matched by age, sex, and body mass index. Max-Z of CA was defined as the maximal Z-score of the proximal LCA or RCA by Dalliarre equation or Fuse calculator.All routine parameters measured during standard exercise test were similar between KD and control groups, except that peak rate pressure products (PRPPs) in KD group 1 to 3 were all lower than corresponding control groups significantly (P = 0.010, 0.020, and 0.049, respectively). PRPPs correlated with Max-Z of CA by both equations modest inversely (by Dallaire, P = 0.017, Spearman rho = -0.301; by Fuse, P = 0.014, Spearman rho = -0.309).Our study recruited larger number of KD patients and provided a newer data of EC of KD patients. Our finding suggests that after acute stage of KD, patients could maintain normal cardiorespiratory fitness. Therefore, we believe that it is important to promote cardiovascular health to KD patients and KD patients should exercise as normal peers. However, since KD patients might still have compromised coronary perfusion during exercise, it remains crucial to assess and monitor cardiovascular risk of KD patients. Max-Z of CA correlates with PRPP modest inversely and might be used as a follow-up indicator of CA reserve during exercise after acute stage of KD.

Cardiopulmonary Function, Exercise Capacity, and Echocardiography Finding of Pediatric Patients With Kawasaki Disease

PubMed Central

Tuan, Sheng-Hui; Li, Min-Hui; Hsu, Miao-Ju; Tsai, Yun-Jeng; Chen, Yin-Han; Liao, Tin-Yun; Lin, Ko-Long

2016-01-01

Abstract Coronary artery (CA) abnormalities influence exercise capacity (EC) of patients with Kawasaki disease (KD), and Z-score of CA is a well established method for detecting CA aneurysm. We studied the influence of KD on cardiopulmonary function and EC; meanwhile we analyzed echocardiographic findings of KD patients. We also assessed the correlation between CA Z-score and EC of KD patients to see if CA Z-score of KD patients could reflect EC during exercise. Sixty-three KD patients were recruited as KD group 1 from children (aged 5–18 y) who received transthoracic echocardiographic examinations and symptom-limited treadmill exercise test for regular follow-up of KD from January 2010 to October 2014 in 1 medical center. We then divided KD group 1 into KD group 2 (<5 y, n = 12) and KD group 3 (≥5 y, n = 51) according to time interval between KD onset to when patients received test. Control groups were matched by age, sex, and body mass index. Max-Z of CA was defined as the maximal Z-score of the proximal LCA or RCA by Dalliarre equation or Fuse calculator. All routine parameters measured during standard exercise test were similar between KD and control groups, except that peak rate pressure products (PRPPs) in KD group 1 to 3 were all lower than corresponding control groups significantly (P = 0.010, 0.020, and 0.049, respectively). PRPPs correlated with Max-Z of CA by both equations modest inversely (by Dallaire, P = 0.017, Spearman rho = −0.301; by Fuse, P = 0.014, Spearman rho = −0.309). Our study recruited larger number of KD patients and provided a newer data of EC of KD patients. Our finding suggests that after acute stage of KD, patients could maintain normal cardiorespiratory fitness. Therefore, we believe that it is important to promote cardiovascular health to KD patients and KD patients should exercise as normal peers. However, since KD patients might still have compromised coronary perfusion during exercise, it remains crucial to assess and monitor cardiovascular risk of KD patients. Max-Z of CA correlates with PRPP modest inversely and might be used as a follow-up indicator of CA reserve during exercise after acute stage of KD. PMID:26765431

Quaternary Tectonic Tilting Governed by Rupture Segments Controls Surface Morphology and Drainage Evolution along the South-Central Coast of Chile

NASA Astrophysics Data System (ADS)

Echtler, H. P.; Bookhagen, B.; Melnick, D.; Strecker, M.

2004-12-01

The Chilean coast represents one of the most active convergent margins in the Pacific rim, where major earthquakes (M>8) have repeatedly ruptured the surface, involving vertical offsets of several meters. Deformation along this coast takes place in large-scale, semi-independent seismotectonic segments with partially overlapping transient boundaries. They are possibly related to reactivated inherited crustal anisotropies; internal seismogenic deformation may be accommodated by structures that have developed during accretionary wedge evolution. Seismotectonic segmentation and the identification of large-scale rupture zones, however, are based on limited seismologic und geodetic observations over short timespans. In order to better define the long-term behavior and deformation rates of these segments and to survey the tectonic impact on the landscape on various temporal and spatial scales, we investigated the south-central coast of Chile (37-38S). There, two highly active, competing seismotectonic compartments influence the coastal and fluvial morphology. A rigorous analysis of the geomorphic features is a key for an assessment of the tectonic evolution during the Quaternary and beyond. We studied the N-S oriented Santa María Island (SMI), 20 km off the coast and only ~70km off the trench, in the transition between the two major Valdivia (46-37S) and Concepción (38-35S) rupture segments. The SMI has been tectonically deformed throughout the Quaternary and comprises two tilt domains with two topographic highs in the north and south that are being tilted eastward. The low-lying and flat eastern part of the island is characterized by a set of emergent Holocene strandlines related to coseismic uplift. We measured detailed surface morphology of these strandlines and E-W traversing ephemeral stream channels with a laser-total station and used these data to calibrate and validate high-resolution, digital imagery. In addition, crucial geomorphic markers were dated by the radiocarbon and optical stimulation methods to better constrain deformation rates. In response to the ongoing deformation, formerly W flowing streams constituting small drainages (< 0.25km2) were inverted and formed closed basins. In contrast, larger streams were reversed or were able to maintain their channels, but formed distinct knickpoints along their longitudinal profiles. In order to reconstruct the Holocene tectonic tilting axis, we connected drainage boundaries of reversed channels and deformation-related knickpoints along more mature rivers. Interestingly, topography clearly indicates that the direction of Pleistocene tectonic tilting was different than that of recent conditions. The Holocene inversion of stream flow associated with continuous uplift may be related to the progressive migration of the tectonic tilting axis in the course of active folding (Melnick et al., this session). The classification of knickpoints and the overall tectonic development also the mainland coast on the Arauco peninsula, during the Quaternary clearly document the surface signature of tectonic segmentation and its spatial evolution through time. The migration of the tilting axes is discussed in relation with active basal accretion and active shortening in the South-Central Chilean forearc.

The tobacco-specific carcinogen-operated calcium channel promotes lung tumorigenesis via IGF2 exocytosis in lung epithelial cells

PubMed Central

Boo, Hye-Jin; Min, Hye-Young; Jang, Hyun-Ji; Yun, Hye Jeong; Smith, John Kendal; Jin, Quanri; Lee, Hyo-Jong; Liu, Diane; Kweon, Hee-Seok; Behrens, Carmen; Lee, J. Jack; Wistuba, Ignacio I.; Lee, Euni; Hong, Waun Ki; Lee, Ho-Young

2016-01-01

Nicotinic acetylcholine receptors (nAChRs) binding to the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces Ca2+ signalling, a mechanism that is implicated in various human cancers. In this study, we investigated the role of NNK-mediated Ca2+ signalling in lung cancer formation. We show significant overexpression of insulin-like growth factors (IGFs) in association with IGF-1R activation in human preneoplastic lung lesions in smokers. NNK induces voltage-dependent calcium channel (VDCC)-intervened calcium influx in airway epithelial cells, resulting in a rapid IGF2 secretion via the regulated pathway and thus IGF-1R activation. Silencing nAChR, α1 subunit of L-type VDCC, or various vesicular trafficking curators, including synaptotagmins and Rabs, or blockade of nAChR/VDCC-mediated Ca2+ influx significantly suppresses NNK-induced IGF2 exocytosis, transformation and tumorigenesis of lung epithelial cells. Publicly available database reveals inverse correlation between use of calcium channel blockers and lung cancer diagnosis. Our data indicate that NNK disrupts the regulated pathway of IGF2 exocytosis and promotes lung tumorigenesis. PMID:27666821

The tobacco-specific carcinogen-operated calcium channel promotes lung tumorigenesis via IGF2 exocytosis in lung epithelial cells.

PubMed

Boo, Hye-Jin; Min, Hye-Young; Jang, Hyun-Ji; Yun, Hye Jeong; Smith, John Kendal; Jin, Quanri; Lee, Hyo-Jong; Liu, Diane; Kweon, Hee-Seok; Behrens, Carmen; Lee, J Jack; Wistuba, Ignacio I; Lee, Euni; Hong, Waun Ki; Lee, Ho-Young

2016-09-26

Nicotinic acetylcholine receptors (nAChRs) binding to the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces Ca 2+ signalling, a mechanism that is implicated in various human cancers. In this study, we investigated the role of NNK-mediated Ca 2+ signalling in lung cancer formation. We show significant overexpression of insulin-like growth factors (IGFs) in association with IGF-1R activation in human preneoplastic lung lesions in smokers. NNK induces voltage-dependent calcium channel (VDCC)-intervened calcium influx in airway epithelial cells, resulting in a rapid IGF2 secretion via the regulated pathway and thus IGF-1R activation. Silencing nAChR, α1 subunit of L-type VDCC, or various vesicular trafficking curators, including synaptotagmins and Rabs, or blockade of nAChR/VDCC-mediated Ca 2+ influx significantly suppresses NNK-induced IGF2 exocytosis, transformation and tumorigenesis of lung epithelial cells. Publicly available database reveals inverse correlation between use of calcium channel blockers and lung cancer diagnosis. Our data indicate that NNK disrupts the regulated pathway of IGF2 exocytosis and promotes lung tumorigenesis.

Tracing Archean sulfur across stitched lithospheric blocks

NASA Astrophysics Data System (ADS)

LaFlamme, Crystal; Fiorentini, Marco; Lindsay, Mark; Wing, Boswell; Selvaraja, Vikraman; Occhipinti, Sandra; Johnson, Simon; Bui, Hao Thi

2017-04-01

Craton margins are loci for volatile exchange among lithospheric geochemical reservoirs during crust formation processes. Here, we seek to revolutionise the current understanding of the planetary flux and lithospheric transfer of volatiles during supercontinent formation by tracing sulfur from the atmosphere-hydrosphere through to the lithosphere during crust formation. To do so, we trace the transfer of sulfur by following mass independently fractionated sulfur at ancient tectonic boundaries has the potential to. Mass independent fractionation of sulfur (MIF-S) is a signature (quantified as Δ33S and Δ36S) that is unique to the Archean sedimentary rock record and imparted to sulfur reservoirs that interacted with the oxygen-poor atmosphere before the Great Oxidation Event (GOE) at ca. 2.4 Ga. Here we present multiple sulfur isotopes from across a Proterozoic post-GOE orogenic belt, formed when Archean cratons were stitched together during supercontinent amalgamation. For the first time, multiple sulfur isotope data are presented spatially to elucidate volatile pathways across lithospheric blocks. Across the orogenic belt, the Proterozoic granitoid and hydrothermal rock records proximal to Archean cratons preserve values of Δ33S up to +0.8\\permil and a Δ33S-Δ36S array of -1.2, whereas magmatic and hydrothermal systems located more distally from the margin do not display any evidence of MIF-S. This is the first study to identify MIF-S in a Proterozoic orogen indicates that tectonic processes controlling lithospheric evolution and crust formation at tectonic boundaries are able to transfer sulfur from Archean supracrustal rock reservoirs to newly formed Proterozoic granitoid crust. The observation of MIF-S in the Proterozoic granitoid rock record has the potential to revolutionise our understanding of secular changes in the evolution of crust formation mechanisms through time.

Anti-thyroid peroxidase antibodies are associated with the absence of distant metastases in patients with newly diagnosed breast cancer.

PubMed

Farahati, Jamshid; Roggenbuck, Dirk; Gilman, Elena; Schütte, Martin; Jagminaite, Elena; Seyed Zakavi, Rasoul; Löning, Thomas; Heissen, Eberhard

2012-04-01

The presence of thyroid peroxidase antibodies (TPOab) are reported to be associated with improved outcome among breast cancer patients. We evaluated the correlation between TPOab and diagnostic parameters among newly diagnosed breast cancer patients. Three hundred and fourteen newly diagnosed patients with breast cancer, diagnosed and treated in Bethesda Essen between January 2002 and June 2006, were included in this study; 258 (82.2%) without TPOab (≤100 IU/mL) and 56 (17.8%) with TPOab (>100 IU/mL). Blood analysis was performed to measure serum levels of carcinoembryonic antigen (CEA), cancer antigen 15-3 (CA-15-3), free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH) and TPOab by radioimmunoassay. Data regarding age, tumor size, grading, TNM classification, receptor status, lymph node, and distant metastases were collected and analyzed from patient reports. Statistics were performed using Pearson’s χ2-test and logistic regression analysis. There were no incidences of distant metastasis among 56 patients with TPOab, whereas 17 (6.6%) of 258 cases without TPOab displayed distant metastases (p=0.04). Logistic regression showed an inverse association of TPOab with CA-15-3 and CEA levels (p<0.001, respectively). Both groups, with and without TPOab, revealed no significant differences with respect to age, tumor size, grading, TNM classification, fT3, fT4, and receptor status. TPOab positive patients had higher TSH levels (2.55±3.58), compared to TPOab negative cases (1.20±1.15) (p<0.001). TPOab occurrence is associated with significantly lower frequency of distant metastases in breast cancer. TPOab level inversely correlates with the conventional tumor markers CA-15-3 and CEA.

Internal Astigmatism in Myopes and Non-myopes: Compensation or Constant?

PubMed Central

Manny, Ruth E.; Deng, Li; Gwiazda, Jane; Hyman, Leslie; Weissberg, Erik; Scheiman, Mitchell; Fern, Karen D.

2016-01-01

Purpose To examine internal astigmatism (IA) in myopes and non-myopes using a new method to assess compensation of corneal astigmatism (CA) by IA, to look for predictors of high IA in young adult myopes and determine if as CA changes IA changes to reduce refractive astigmatism (RA) in an active compensatory process in myopes. Methods Right eye keratometry and cycloplegic autorefraction were measured annually over 14 years in 367 myopes and once in 204 non-myopes age- (mean 21.91 years ± 1.47), gender-, and ethnicity-matched to myopes at year 12. CA and RA at the corneal plane were expressed as J0, J45. IA = RA - CA. Inverse power transformation provided cylinder power and axis of IA for the compensation factor (IA/CA). Analyses included: 1) paired and unpaired t-tests (refractive data), 2) chi-square tests (distributions of compensation factor), 3) logistic regression analysis (predictors of high IA), and 4) linear mixed models (time effect on RA, CA and IA). Results The magnitude of IAJ0 varied by refractive error (myopes −0.25 ±0.24 vs non-myopes −0.32 ± 0.21, p<0.001). Compensation of CA by IA was poorer in myopes than non-myopes (χ2 p<0.001). When matched by CA, compensation remained poorer in myopes than non-myopes (χ2 all p≤ 0.04). Within each refractive group compensation was better when CA was low than high (χ2 p<0.001). When CA was low in myopes, high IA (≥1.00D) was less likely (p=0.01). Longitudinal follow-up of myopes found no evidence for an active compensatory role for IA as CA increased over time. There were differences in IAJ0 by ethnicity over time (p<0.0001). Conclusions In myopic and non-myopic eyes with low amounts of CA, IA may reduce CA’s contribution to RA, but IA is not a constant. However, there is no evidence for an active compensatory role for IA reducing CA in myopes. PMID:27564515

Joint Inversion for 3-Dimensional S-Velocity Mantle Structure Along the Tethyan Margin

DTIC Science & Technology

2007-09-01

Hindu Kush and encompasses northeastern Africa, the Arabian peninsula, the Middle East, and part of the Atlantic Ocean for reference. We have fitted...several microplates within an area of one quarter of the Earth’s circumference yields this region rich with tectonic complexity. The three...assigned the largest errors. For the oceans we use a constraint of 10 km for Moho depth, but only for points also covered by data from our other data sets

Birefringence and incipient plastic deformation in elastically overdriven [100] CaF2 under shock compression

NASA Astrophysics Data System (ADS)

Li, Y.; Zhou, X. M.; Cai, Y.; Liu, C. L.; Luo, S. N.

2018-04-01

[100] CaF2 single crystals are shock-compressed via symmetric planar impact, and the flyer plate-target interface velocity histories are measured with a laser displacement interferometry. The shock loading is slightly above the Hugoniot elastic limit to investigate incipient plasticity and its kinetics, and its effects on optical properties and deformation inhomogeneity. Fringe patterns demonstrate different features in modulation of fringe amplitude, including birefringence and complicated modulations. The birefringence is attributed to local lattice rotation accompanying incipient plasticity. Spatially resolved measurements show inhomogeneity in deformation, birefringence, and fringe pattern evolutions, most likely caused by the inhomogeneity associated with lattice rotation and dislocation slip. Transiently overdriven elastic states are observed, and the incubation time for incipient plasticity decreases inversely with increasing overdrive by the elastic shock.

Reassessment of Paleo- and Mesoproterozoic basin sediments of Arizona: Implications for tectonic growth of southern Laurentia and global tectonic configurations

NASA Astrophysics Data System (ADS)

Doe, Michael Frederick

Proterozoic crustal provinces that underlie much of the United States record prolonged southward growth of the North American craton (Laurentia) between ca. 1.8 and 1.0 Ga. Exposures throughout central Arizona's Tonto Basin represent multiple generations of sedimentary basins formed during Proterozoic accretion. Metasedimentary rocks sampled across Tonto Basin resulted have identified remnants of a previously undated but potentially widespread Mesoproterozoic basin called the Yankee Joe Basin. Sediments of Yankee Joe Basin are particularly interesting because they have depositional age's ca. 200 m.y. younger than previously thought and because they are rich in detrital zircons with ages between 1.6-1.48 Ga, a time period not widely represented in the igneous record of Laurentia. Metasedimentary rocks with similar age and provenance are found in northern New Mexico and in the lower parts of the Belt Supergroup in northern Idaho, Montana, and Canada. Zircon ages and Hf isotopic characteristics suggest the distinctive 1.6-1.48 Ga grains might have been derived from non-Laurentian sources, most likely one or more formerly adjacent cratons such as north Australia. Circa 1.48-1.43 Ga units in the Yankee Joe Basin rest disconformably on Paleoproterozoic quartzite, and all were deformed together during northwest-directed foreland-style thrusting. This event was previously interpreted to represent the ca. 1.66-1.60 Ga Mazatzal orogeny. However, new findings challenge this view and suggest a major deformation event occurred ca. 1.47-1.45 Ga, possibly representing the Picuris orogeny as recently described in northern New Mexico. Regional thrust faulting during the Mesoproterozoic might have unroofed and removed significant portions of the Yankee Joe section, potentially shedding detritus north from the thrust front into the upper parts of the Belt-Purcell basin. Detrital zircon ages and hafnium isotope compositions provide a critical test of sediment provenance and depositional age and were used to reassess sedimentary age and sources multiple Proterozoic unconformity-bound metasedimentary successions exposed across Arizona. These successions represent a series of ca. 1.75 to 1.3 Ga basins that span the Proterozoic accretionary provinces of southwestern Laurentia, representing key elements in the tectonic evolution of the continental margin. The ca. 1.75 Ga Vishnu Schist contains a bimodal detrital zircon age distribution with prominent Archean (2.5 Ga) and Early Paleoproterozoic (1.8 Ga) populations and minor juvenile 1.75 Ga input. The predominance of 3.3-1.8 Ga detrital zircon ages and initial epsilon Hf (epsilonHf) values of +4 to -13 in both detrital grains of the Vishnu Schist and xenocrystic grains in plutons from cross-cutting plutons suggests the Vishnu Schist was derived primarily from recycling of the Mojave and other older basement provinces, possibly including one or more outboard cratons. In contrast, the ca. 1.74-1.72 Ga Jerome and ca. 1.72 Ga Alder successions of central Arizona, show a marked shift to strongly unimodal detrital zircon age distributions with initial epsilonHf values ranging from +13 to -5, generally more positive and near-juvenile. Cross-cutting ca. 1.74-1.72 Ga plutons that intrude these rocks also have largely juvenile Hf isotopic signatures. The prominent ca. 1.73 Ga age peaks and relatively juvenile epsilonHf values of detrital grains and plutons are consistent with first-cycle sediment derived from local arc systems formed during progressive assembly of the Yavapai province with the older Mojave province. The ca.1.66-1.63 Ga Mazatzal succession is more compositionally mature and contains broader unimodal detrital zircon age spectra, interpreted to represent increasing regional crustal recycling following the culmination of the Yavapai orogeny. In the northern Tonto Basin, detrital zircon age populations from similar looking quartzite and shale successions were used to develop new regional correlations. First, the Houdon Quartzite of the Alder Group was correlated to the Pine Creek Conglomerate. Second, the Mazatzal Group that unconformably overlies the Alder Group, was found to be deposited ca. 1631 +/- 22 Ma, consistent with the White Ledges Formation and the quartzite succession at Four Peaks. Third, a new detrial zircon population collected from the upper part of the argillaceous section in the core of the Four Peaks synform yield ages between 1591-1560 Ma suggesting this section is correlative to the Yankee Joe Formation. (Abstract shortened by UMI.)

Early Neoarchaean A-type granitic magmatism by crustal reworking in Singhbhum craton: Evidence from Pala Lahara area, Orissa

NASA Astrophysics Data System (ADS)

Topno, Abhishek; Dey, Sukanta; Liu, Yongsheng; Zong, Keqing

2018-04-01

Several volumetrically minor ˜ 2.8 Ga anorogenic granites and rhyolites occur along the marginal part of the Singhbhum craton whose origin and role in crustal evolution are poorly constrained. This contribution presents petrographic, geochemical, zircon U-Pb and trace element, and mineral chemical data on such granites exposed in the Pala Lahara area to understand their petrogenesis and tectonic setting. The Pala Lahara granites are calc-alkaline, high-silica rocks and define a zircon U-Pb age of 2.79 Ga. These granites are ferroan, weakly metaluminous, depleted in Al, Ca and Mg and rich in LILE and HFSE. They are classified as A2-type granites with high Y/Nb ratios. Geochemical characteristics (high SiO2 and K2O, very low MgO, Mg#, Cr, Ni and V, negative Eu anomaly, flat HREE and low Sr/Y) and comparison with melts reported by published experimental studies suggest an origin through high-temperature, shallow crustal melting of tonalitic/granodioritic source similar to the ˜ 3.3 Ga Singhbhum Granite. Intrusion of the Pala Lahara granites was coeval with prominent mafic magmatism in the Singhbhum craton (e.g., the Dhanjori mafic volcanic rocks and NNE-SSW trending mafic dyke swarm). It is suggested that the ˜ 2.8 Ga A-type granites in the Singhbhum craton mark a significant crustal reworking event attendant to mantle-derived mafic magmatism in an extensional tectonic setting.

Cenozoic intracontinental deformation of the Kopeh Dagh Belt, Northeastern Iran

NASA Astrophysics Data System (ADS)

Chu, Yang; Wan, Bo; Chen, Ling; Talebian, Morteza

2016-04-01

Compressional intracontinental orogens represent large tectonic zones far from plate boundaries. Since intracontinental mountain belts cannot be framed in the conventional plate tectonics theory, several hypotheses have been proposed to account for the formations of these mountain belts. The far-field effect of collision/subduction at plate margins is now well accepted for the origin and evolution of the intracontinental crust thickening, as exemplified by the Miocene tectonics of central Asia. In northern Iran, the Binalud-Alborz mountain belt witnessed the Triassic tectonothermal events (Cimmerian orogeny), which are interpreted as the result of the Paleotethys Ocean closure between the Eurasia and Central Iran blocks. The Kopeh Dagh Belt, located to the north of the Binalud-Alborz Belt, has experienced two significant tectonic phases: (1) Jurassic to Eocene rifting with more than 7 km of sediments; and (2) Late Eocene-Early Oligocene to Quaternary continuous compression. Due to the high seismicity, deformation associated with earthquakes has received more and more attention; however, the deformation pattern and architecture of this range remain poorly understood. Detailed field observations on the Cenozoic deformation indicate that the Kopeh Dagh Belt can be divided into a western zone and an eastern zone, separated by a series of dextral strike-slip faults, i.e. the Bakharden-Quchan Fault System. The eastern zone characterized by km-scale box-fold structures, associated with southwest-dipping reverse faults and top-to-the NE kinematics. In contrast, the western zone shows top-to-the SW kinematics, and the deformation intensifies from NE to SW. In the northern part of this zone, large-scale asymmetrical anticlines exhibit SW-directed vergence with subordinate thrusts and folds, whereas symmetrical anticlines are observed in the southern part. In regard to its tectonic feature, the Kopeh Dagh Belt is a typical Cenozoic intracontinental belt without ophiolites or arc magmatism. During the Jurassic to Eocene rifting, this belt acted as the southern boundary of the Amu Darya Basin with normal faulting, which is also widespread in the South Caspian Sea and the Black Sea. Moreover, such an extended area became a relatively weak zone within the Eurasian Plate, and could be easily reworked. Because of the collision in the Zagros Belt, the intracontinental compression commenced as early as Late Eocene to Early Oligocene, which is interpreted as tectonic inversion along this weak zone. The western zone of the Kopeh Dagh Belt was also affected by southerly indentation/extrusion of the South Caspian block since middle Miocene, possibly resulting in the different deformation patterns between the western and eastern zones.

The use of inverse phase gas chromatography to measure the surface energy of crystalline, amorphous, and recently milled lactose.

PubMed

Newell, H E; Buckton, G; Butler, D A; Thielmann, F; Williams, D R

2001-05-01

To assess differences in surface energy due to processing induced disorder and to understand whether the disorder dominated the surfaces of particles. Inverse gas chromatography was used to compare the surface energies of crystalline, amorphous, and ball milled lactose. The milling process made ca 1% of the lactose amorphous, however the dispersive contribution to surface energy was 31.2, 37.1, and 41.6 mJ m(-2) for crystalline, spray dried and milled lactose, respectively. A physical mixture of crystalline (99%) and amorphous (1%) material had a dispersive surface energy of 31.5 mJ m(-2). Milling had made the surface energy similar to that of the amorphous material in a manner that was very different to a physical mixture of the same amorphous content. The milled material will have similar interfacial interactions to the 100% amorphous material.

An increase or a decrease in myosin II phosphorylation inhibits macrophage motility

PubMed Central

1991-01-01

Myosin II purified from mammalian non-muscle cells is phosphorylated on the 20-kD light chain subunit (MLC20) by the Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK). The importance of MLC20 phosphorylation in regulating cell motility was investigated by introducing either antibodies to MLCK (MK-Ab) or a Ca2+/calmodulin- independent, constitutively active form of MLCK (MK-) into macrophages. The effects of these proteins on cell motility were then determined using a quantitative chemotaxis assay. Chemotaxis is significantly diminished in macrophages containing MK-Ab compared to macrophages containing control antibodies. Moreover, there is an inverse relationship between the number of cells that migrate and the amount of MK-Ab introduced into cells. Interestingly, there is also an inverse relationship between the number of cells that migrate and the amount of MK- introduced into cells. Other experiments demonstrated that MK-Ab decreased intracellular MLC20 phosphorylation while MK- increased MLC20 phosphorylation. MK- also increased the amount of myosin associated with the cytoskeleton. These data demonstrate that the regulation of MLCK is an important aspect of cell motility and suggest that MLC20 phosphorylation must be maintained within narrow limits during translational motility by mammalian cells. PMID:2071674

Impact of anion replacement on the optoelectronic and thermoelectric properties of CaMg2X2, X= (N, P, As, Sb, Bi) compounds

NASA Astrophysics Data System (ADS)

Khan, Abdul Ahad; Yaseen, M.; Laref, A.; Murtaza, G.

2018-07-01

The structural, electronic, optical and thermoelectric properties of ternary CaMg2X2 (X = N, P, As, Sb and Bi) compounds are investigated using all electrons full potential linearized augment plane wave method. By using generalized gradient approximation (GGA), unit cell volumes of the compounds are optimized. For calculations of optical and electronic properties the modified Becke Johnson exchange potential is used along with the GGA. The direct energy band gap decreases by replacing the pnictogen elements, while indirect bandgap also decreases except for CaMg2As2. The optical properties show a prominent variation over the change of anion from N to Bi. There is inverse variation between refractive index and the band gap. The refractive indices of these compounds are high in the visible region and sharply decreased in the ultraviolet region. The thermoelectric properties are also studied using Boltzmann statistics through BoltzTrap code. A positive non-zero value of Seebeck coefficient shows a P-type semiconducting behavior of these compounds. High figure of merits (ZT) and optical conductivity peaks for all compounds reveal that they are good candidates for the thermo-electric and optoelectronics devices.

Mathematical modeling physiological effects of the overexpression of β2-adrenoceptors in mouse ventricular myocytes.

PubMed

Rozier, Kelvin; Bondarenko, Vladimir E

2018-03-01

Transgenic (TG) mice overexpressing β 2 -adrenergic receptors (β 2 -ARs) demonstrate enhanced myocardial function, which manifests in increased basal adenylyl cyclase activity, enhanced atrial contractility, and increased left ventricular function in vivo. To gain insights into the mechanisms of these effects, we developed a comprehensive mathematical model of the mouse ventricular myocyte overexpressing β 2 -ARs. We found that most of the β 2 -ARs are active in control conditions in TG mice. The simulations describe the dynamics of major signaling molecules in different subcellular compartments, increased basal adenylyl cyclase activity, modifications of action potential shape and duration, and the effects on L-type Ca 2+ current and intracellular Ca 2+ concentration ([Ca 2+ ] i ) transients upon stimulation of β 2 -ARs in control, after the application of pertussis toxin, upon stimulation with a specific β 2 -AR agonist zinterol, and upon stimulation with zinterol in the presence of pertussis toxin. The model also describes the effects of the β 2 -AR inverse agonist ICI-118,551 on adenylyl cyclase activity, action potential, and [Ca 2+ ] i transients. The simulation results were compared with experimental data obtained in ventricular myocytes from TG mice overexpressing β 2 -ARs and with simulation data on wild-type mice. In conclusion, a new comprehensive mathematical model was developed that describes multiple experimental data on TG mice overexpressing β 2 -ARs and can be used to test numerous hypotheses. As an example, using the developed model, we proved the hypothesis of the major contribution of L-type Ca 2+ current to the changes in the action potential and [Ca 2+ ] i transient upon stimulation of β 2 -ARs with zinterol. NEW & NOTEWORTHY We developed a new mathematical model for transgenic mouse ventricular myocytes overexpressing β 2 -adrenoceptors that describes the experimental findings in transgenic mice. The model reveals mechanisms of the differential effects of stimulation of β 2 -adrenoceptors in wild-type and transgenic mice overexpressing β 2 -adrenoceptors.

Arterial α2-Na+ pump expression influences blood pressure: lessons from novel, genetically engineered smooth muscle-specific α2 mice.

PubMed

Chen, Ling; Song, Hong; Wang, Youhua; Lee, Jane C; Kotlikoff, Michael I; Pritchard, Tracy J; Paul, Richard J; Zhang, Jin; Blaustein, Mordecai P

2015-09-01

Arterial myocytes express α1-catalytic subunit isoform Na(+) pumps (75-80% of total), which are ouabain resistant in rodents, and high ouabain affinity α2-Na(+) pumps. Mice with globally reduced α2-pumps (but not α1-pumps), mice with mutant ouabain-resistant α2-pumps, and mice with a smooth muscle (SM)-specific α2-transgene (α2 (SM-Tg)) that induces overexpression all have altered blood pressure (BP) phenotypes. We generated α2 (SM-DN) mice with SM-specific α2 (not α1) reduction (>50%) using nonfunctional dominant negative (DN) α2. We compared α2 (SM-DN) and α2 (SM-Tg) mice to controls to determine how arterial SM α2-pumps affect vasoconstriction and BP. α2 (SM-DN) mice had elevated basal mean BP (mean BP by telemetry: 117 ± 4 vs. 106 ± 1 mmHg, n = 7/7, P < 0.01) and enhanced BP responses to chronic ANG II infusion (240 ng·kg(-1)·min(-1)) and high (6%) NaCl. Several arterial Ca(2+) transporters, including Na(+)/Ca(2+) exchanger 1 (NCX1) and sarcoplasmic reticulum and plasma membrane Ca(2+) pumps [sarco(endo)plasmic reticulum Ca(2+)-ATPase 2 (SERCA2) and plasma membrane Ca(2+)-ATPase 1 (PMCA1)], were also reduced (>50%). α2 (SM-DN) mouse isolated small arteries had reduced myogenic reactivity, perhaps because of reduced Ca(2+) transporter expression. In contrast, α2 (SM-Tg) mouse aortas overexpressed α2 (>2-fold), NCX1, SERCA2, and PMCA1 (43). α2 (SM-Tg) mice had reduced basal mean BP (104 ± 1 vs. 109 ± 2 mmHg, n = 15/9, P < 0.02) and attenuated BP responses to chronic ANG II (300-400 ng·kg(-1)·min(-1)) with or without 2% NaCl but normal myogenic reactivity. NCX1 expression was inversely related to basal BP in SM-α2 engineered mice but was directly related in SM-NCX1 engineered mice. NCX1, which usually mediates arterial Ca(2+) entry, and α2-Na(+) pumps colocalize at plasma membrane-sarcoplasmic reticulum junctions and functionally couple via the local Na(+) gradient to help regulate cell Ca(2+). Altered Ca(2+) transporter expression in SM-α2 engineered mice apparently compensates to minimize Ca(2+) overload (α2 (SM-DN)) or depletion (α2 (SM-Tg)) and attenuate BP changes. In contrast, Ca(2+) transporter upregulation, observed in many rodent hypertension models, should enhance Ca(2+) entry and signaling and contribute significantly to BP elevation. Copyright © 2015 the American Physiological Society.

Holocene geologic and climatic history around the Gulf of Alaska

USGS Publications Warehouse

Mann, D.H.; Crowell, A.L.; Hamilton, T.D.; Finney, B.P.

1998-01-01

Though not as dramatic as during the last Ice Age, pronounced climatic changes occurred in the northeastern Pacific over the last 10,000 years. Summers warmer and drier than today's accompanied a Hypsithermal interval between 9 and 6 ka. Subsequent Neoglaciation was marked by glacier expansion after 5-6 ka and the assembly of modern-type plant communities by 3-4 ka. The Neoglacial interval contained alternating cold and warm intervals, each lasting several hundred years to one millennium, and including both the Medieval Warm Period (ca. AD 900-1350) and the Little Ice Age (ca. AD 1350-1900). Salmon abundance fluctuated during the Little Ice Age in response to local glaciation and probably also to changes in the intensity of the Aleutian Low. Although poorly understood at present, climate fluctuations at all time scales were intimately connected with oceanographic changes in the North Pacific Ocean. The Gulf of Alaska region is tectonically highly active, resulting in a history of frequent geological catastrophes during the Holocene. Twelve to 14 major volcanic eruptions occurred since 12 ka. At intervals of 20-100 years, large earthquakes have raised and lowered sea level instantaneously by meters and generated destructive tsunamis. Sea level has often varied markedly between sites only 50-100 km apart due to tectonism and the isostatic effects of glacier fluctuations.

Morpho-structural evolution of a volcanic island developed inside an active oceanic rift: S. Miguel Island (Terceira Rift, Azores)

NASA Astrophysics Data System (ADS)

Sibrant, A. L. R.; Hildenbrand, A.; Marques, F. O.; Weiss, B.; Boulesteix, T.; Hübscher, C.; Lüdmann, T.; Costa, A. C. G.; Catalão, J. C.

2015-08-01

The evolution of volcanic islands is generally marked by fast construction phases alternating with destruction by a variety of mass-wasting processes. More specifically, volcanic islands located in areas of intense regional deformation can be particularly prone to gravitational destabilisation. The island of S. Miguel (Azores) has developed during the last 1 Myr inside the active Terceira Rift, a major tectonic structure materializing the present boundary between the Eurasian and Nubian lithospheric plates. In this work, we depict the evolution of the island, based on high-resolution DEM data, stratigraphic and structural analyses, high-precision K-Ar dating on separated mineral phases, and offshore data (bathymetry and seismic profiles). The new results indicate that: (1) the oldest volcanic complex (Nordeste), composing the easternmost part of the island, was dominantly active between ca. 850 and 750 ka, and was subsequently affected by a major south-directed flank collapse. (2) Between at least 500 ka and 250 ka, the landslide depression was massively filled by a thick lava succession erupted from volcanic cones and domes distributed along the main E-W collapse scar. (3) Since 250 kyr, the western part of this succession (Furnas area) was affected by multiple vertical collapses; associated plinian eruptions produced large pyroclastic deposits, here dated at ca. 60 ka and less than 25 ka. (4) During the same period, the eastern part of the landslide scar was enlarged by retrogressive erosion, producing the large Povoação valley, which was gradually filled by sediments and young volcanic products. (5) The Fogo volcano, in the middle of S. Miguel, is here dated between ca. 270 and 17 ka, and was affected by, at least, one southwards flank collapse. (6) The Sete Cidades volcano, in the western end of the island, is here dated between ca. 91 and 13 ka, and experienced mutliple caldera collapses; a landslide to the North is also suspected from the presence of a subtle morphologic scar covered by recent lava flows erupted from alignments of basaltic strombolian cones. The predominance of the N150° and N75° trends in the island suggest that the tectonics of the Terceira Rift controlled the location and the distribution of the volcanism, and to some extent the various destruction events.

Calcium Isotope (δ44/40Ca) Composition of Morozovella Velascoensis During the Paleocene Eocene Thermal Maximum Ocean Acidification Event

NASA Astrophysics Data System (ADS)

Kitch, G. D.; Jacobson, A. D.; Hurtgen, M.; Sageman, B. B.; Harper, D. T.; Zachos, J. C.

2017-12-01

Ocean acidification (OA) events are transient disruptions to the carbonate chemistry of seawater that involve decreases in pH, [CO32-] and carbonate mineral saturation states (Ω). Numerical modeling studies predict that the Ca isotope (δ44/40Ca) composition of primary marine carbonate should be sensitive to OA1, and recent evidence from the rock record may support this hypothesis2. Boron isotope (δ11B) data for the planktonic foraminifera Morozovella velascoensis indicate that the Paleocene-Eocene Thermal Maximum (PETM; 55 Mya) was an interval of pronounced OA3, although the Ca isotope composition of the bulk carbonate record appears to show post-burial diagenetic effects4. To further evaluate the Ca isotope proxy, we used a high-precision (2σSD=±0.04‰), double-spike (43Ca-42Ca) TIMS method5 to measure δ44/40Ca values of well-preserved M. velascoensis tests spanning the PETM. M. velascoensis tests (250-355 µm) were picked from samples recovered during ODP Leg 198, Site 1209 on Shatsky Rise in the equatorial Pacific. Five M. velascoensis tests were combined per sample, dissolved, spiked, and analyzed using a Triton TIMS. Repeat dissolutions of ten samples gave δ44/40Ca values within ±0.04‰ of the original measurements. Method and procedural blanks were negligible. δ44/40Ca values are elevated, even before the negative carbon isotope excursion (CIE) that marks the PETM. When δ11/10B values decrease during the CIE, δ44/40Ca values remain elevated, but then decrease by 0.10‰ as δ11B values return to pre-CIE levels. The apparent inverse correlation between δ44/40Ca and δ11B values suggests that Ca isotope fractionation by M. velascoensis was sensitive to OA. A decrease in pH indicated by lower δ11B values is consistent with higher δ44/40Ca values (decreased fractionation) due to elevated [Ca2+]/[CO32-] ratios and reduced W. The Ca isotope composition of pristine foraminiferal calcite may have potential for reconstructing [CO32-]. The current, preliminary dataset may indicate changes in [CO32-] prior to the CIE. 1Nielsen et al., 2012. 2Du Vivier et al., 2015. 3Penman et al., 2014. 4Griffith et al., 2015. 5Lehn et al., 2013.

Phosphoproteomic Analysis Reveals a Novel Mechanism of CaMKIIα Regulation Inversely Induced by Cocaine Memory Extinction versus Reconsolidation

PubMed Central

Rich, Matthew T.; Abbott, Thomas B.; Chung, Lisa; Gulcicek, Erol E.; Stone, Kathryn L.; Colangelo, Christopher M.; Lam, TuKiet T.; Nairn, Angus C.; Taylor, Jane R.

2016-01-01

Successful addiction treatment depends on maintaining long-term abstinence, making relapse prevention an essential therapeutic goal. However, exposure to environmental cues associated with drug use often thwarts abstinence efforts by triggering drug using memories that drive craving and relapse. We sought to develop a dual approach for weakening cocaine memories through phosphoproteomic identification of targets regulated in opposite directions by memory extinction compared with reconsolidation in male Sprague-Dawley rats that had been trained to self-administer cocaine paired with an audiovisual cue. We discovered a novel, inversely regulated, memory-dependent phosphorylation event on calcium-calmodulin-dependent kinase II α (CaMKIIα) at serine (S)331. Correspondingly, extinction-associated S331 phosphorylation inhibited CaMKIIα activity. Intra-basolateral amygdala inhibition of CaMKII promoted memory extinction and disrupted reconsolidation, leading to a reduction in subsequent cue-induced reinstatement. CaMKII inhibition had no effect if the memory was neither retrieved nor extinguished. Therefore, inhibition of CaMKII represents a novel mechanism for memory-based addiction treatment that leverages both extinction enhancement and reconsolidation disruption to reduce relapse-like behavior. SIGNIFICANCE STATEMENT Preventing relapse to drug use is an important goal for the successful treatment of addictive disorders. Relapse-prevention therapies attempt to interfere with drug-associated memories, but are often hindered by unintentional memory strengthening. In this study, we identify phosphorylation events that are bidirectionally regulated by the reconsolidation versus extinction of a cocaine-associated memory, including a novel site on CaMKIIα. Additionally, using a rodent model of addiction, we show that CaMKII inhibition in the amygdala can reduce relapse-like behavior. Together, our data supports the existence of mechanisms that can be used to enhance current strategies for addiction treatment. PMID:27445140

Seismological evidence of the Hales discontinuity in northeast India

NASA Astrophysics Data System (ADS)

Anand, Aakash; Bora, Dipok K.; Borah, Kajaljyoti; Madhab Borgohain, Jayanta

2018-04-01

The crust and upper mantle shear wave velocity structure beneath the northeast India is estimated by joint inversion of Rayleigh wave group velocity and receiver function, calculated from teleseismic earthquakes data recorded at nine broadband seismic stations. The Assam valley and the Shillong-Mikir plateau are the two important tectonic blocks in the northeast India, which are surrounded by the Himalayan collision zone in the north, Indo-Burma subduction zone in the east and by the Bengal basin in the south. The joint inversion followed by forward modeling reveal crustal thicknesses of 30-34 km beneath the Shillong plateau, 36 km beneath the Mikir hills and 38-40 km beneath the Assam valley with an average shear wave velocity (Vs) of 3.4-3.5 km/s. The estimated low upper mantle shear wave velocity (Vsn) 4.2-4.3 km/s may be due to the rock composition or grain size or increased temperature and partial melt (<1%) in the upper mantle, or an effect of all. Also, we report for the first time, the existence of the Hales discontinuity at depths 56-74 km with Vs ∼4.4-4.6 km/s. Variable depth of the Hales discontinuity may be explained by the geotherm and/or addition of Cr3+ and Fe2+ in the spinel-garnet system.

(41)Ca in tooth enamel. Part I: a biological signature of neutron exposure in atomic bomb survivors.

PubMed

Wallner, A; Rühm, W; Rugel, G; Nakamura, N; Arazi, A; Faestermann, T; Knie, K; Maier, H J; Korschinek, G

2010-08-01

The detection of (41)Ca atoms in tooth enamel using accelerator mass spectrometry is suggested as a method capable of reconstructing thermal neutron exposures from atomic bomb survivors in Hiroshima and Nagasaki. In general, (41)Ca atoms are produced via thermal neutron capture by stable (40)Ca. Thus any (41)Ca atoms present in the tooth enamel of the survivors would be due to neutron exposure from both natural sources and radiation from the bomb. Tooth samples from five survivors in a control group with negligible neutron exposure were used to investigate the natural (41)Ca content in tooth enamel, and 16 tooth samples from 13 survivors were used to estimate bomb-related neutron exposure. The results showed that the mean (41)Ca/Ca isotope ratio was (0.17 +/- 0.05) x 10(-14) in the control samples and increased to 2 x 10(-14) for survivors who were proximally exposed to the bomb. The (41)Ca/Ca ratios showed an inverse correlation with distance from the hypocenter at the time of the bombing, similar to values that have been derived from theoretical free-in-air thermal-neutron transport calculations. Given that gamma-ray doses were determined earlier for the same tooth samples by means of electron spin resonance (ESR, or electron paramagnetic resonance, EPR), these results can serve to validate neutron exposures that were calculated individually for the survivors but that had to incorporate a number of assumptions (e.g. shielding conditions for the survivors).

Tectonic controls on the long-term carbon isotope mass balance.

PubMed

Shields, Graham A; Mills, Benjamin J W

2017-04-25

The long-term, steady-state marine carbon isotope record reflects changes to the proportional burial rate of organic carbon relative to total carbon on a global scale. For this reason, times of high δ 13 C are conventionally interpreted to be oxygenation events caused by excess organic burial. Here we show that the carbon isotope mass balance is also significantly affected by tectonic uplift and erosion via changes to the inorganic carbon cycle that are independent of changes to the isotopic composition of carbon input. This view is supported by inverse covariance between δ 13 C and a range of uplift proxies, including seawater 87 Sr/ 86 Sr, which demonstrates how erosional forcing of carbonate weathering outweighs that of organic burial on geological timescales. A model of the long-term carbon cycle shows that increases in δ 13 C need not be associated with increased organic burial and that alternative tectonic drivers (erosion, outgassing) provide testable and plausible explanations for sustained deviations from the long-term δ 13 C mean. Our approach emphasizes the commonly overlooked difference between how net and gross carbon fluxes affect the long-term carbon isotope mass balance, and may lead to reassessment of the role that the δ 13 C record plays in reconstructing the oxygenation of earth's surface environment.

Neotectonic and Geomorphological Characteristics of the Ma Pi Leng Area (Ha Giang Province, North Vietnam): Implications for Improving the Worth of Vietnamese Geological Heritage

NASA Astrophysics Data System (ADS)

Van Bui, Thom; Huy Nguyen, Thinh; Duc Nguyen, Tung

2018-03-01

Ma Pi Leng area is the core part of Dong Van karst plateau geopark, and is a region of high diversity of geology and tectonics in Vietnam. This region has experienced strong uplift motions that have created three grades of regional relief: 1400-1600 m; 1100-1200 m and 500-600 m. This geomorphology is in turn strongly eroded by the stream systems and divided into different structural blocks controlled by the faults. During the neotectonic stage, several modes of faulting have occurred in Ma Pi Leng such as strikeslip, normal, extension, riverse faults. The NW-SE fault system had a decisive role in determining the structural pattern of the region. The tectonic fractures, at the largest scale, are hundreds of meters high and up to a kilometer long. Tectonic activities, together with exogenic processes, have made regional relief strongly diverse with strips of horsts and grabens as well as laddersteps-shaped escarpments, inverse topography, high cliffs and deep canyons. Besides that there are also the caves at varying levels of height, chains of sinkholes, and pyramidal mountainous peaks. Ma Pi Leng area is truly majestic and worthy of tourist attractions both in terms of scientific value and natural landscape.

Tectonic controls on the long-term carbon isotope mass balance

PubMed Central

Mills, Benjamin J. W.

2017-01-01

The long-term, steady-state marine carbon isotope record reflects changes to the proportional burial rate of organic carbon relative to total carbon on a global scale. For this reason, times of high δ13C are conventionally interpreted to be oxygenation events caused by excess organic burial. Here we show that the carbon isotope mass balance is also significantly affected by tectonic uplift and erosion via changes to the inorganic carbon cycle that are independent of changes to the isotopic composition of carbon input. This view is supported by inverse covariance between δ13C and a range of uplift proxies, including seawater 87Sr/86Sr, which demonstrates how erosional forcing of carbonate weathering outweighs that of organic burial on geological timescales. A model of the long-term carbon cycle shows that increases in δ13C need not be associated with increased organic burial and that alternative tectonic drivers (erosion, outgassing) provide testable and plausible explanations for sustained deviations from the long-term δ13C mean. Our approach emphasizes the commonly overlooked difference between how net and gross carbon fluxes affect the long-term carbon isotope mass balance, and may lead to reassessment of the role that the δ13C record plays in reconstructing the oxygenation of earth’s surface environment. PMID:28396434

Deformation patterns in the southwestern part of the Mediterranean Ridge (South Matapan Trench, Western Greece)

NASA Astrophysics Data System (ADS)

Andronikidis, Nikolaos; Kokinou, Eleni; Vafidis, Antonios; Kamberis, Evangelos; Manoutsoglou, Emmanouil

2017-12-01

Seismic reflection data and bathymetry analyses, together with geological information, are combined in the present work to identify seabed structural deformation and crustal structure in the Western Mediterranean Ridge (the backstop and the South Matapan Trench). As a first step, we apply bathymetric data and state of art methods of pattern recognition to automatically detect seabed lineaments, which are possibly related to the presence of tectonic structures (faults). The resulting pattern is tied to seismic reflection data, further assisting in the construction of a stratigraphic and structural model for this part of the Mediterranean Ridge. Structural elements and stratigraphic units in the final model are estimated based on: (a) the detected lineaments on the seabed, (b) the distribution of the interval velocities and the presence of velocity inversions, (c) the continuity and the amplitudes of the seismic reflections, the seismic structure of the units and (d) well and stratigraphic data as well as the main tectonic structures from the nearest onshore areas. Seabed morphology in the study area is probably related with the past and recent tectonics movements that result from African and European plates' convergence. Backthrusts and reverse faults, flower structures and deep normal faults are among the most important extensional/compressional structures interpreted in the study area.

Determination of the Geometric Form of a Plane of a Tectonic Gap as the Inverse III-posed Problem of Mathematical Physics

NASA Astrophysics Data System (ADS)

Sirota, Dmitry; Ivanov, Vadim

2017-11-01

Any mining operations influence stability of natural and technogenic massifs are the reason of emergence of the sources of differences of mechanical tension. These sources generate a quasistationary electric field with a Newtonian potential. The paper reviews the method of determining the shape and size of a flat source field with this kind of potential. This common problem meets in many fields of mining: geological exploration mineral resources, ore deposits, control of mining by underground method, determining coal self-heating source, localization of the rock crack's sources and other applied problems of practical physics. This problems are ill-posed and inverse and solved by converting to Fredholm-Uryson integral equation of the first kind. This equation will be solved by A.N. Tikhonov regularization method.

Ancient plate kinematics derived from the deformation pattern of continental crust: Paleo- and Neo-Tethys opening coeval with prolonged Gondwana-Laurussia convergence

NASA Astrophysics Data System (ADS)

Kroner, Uwe; Roscher, Marco; Romer, Rolf L.

2016-06-01

The formation and destruction of supercontinents requires prolonged convergent tectonics between particular plates, followed by intra-continental extension during subsequent breakup stages. A specific feature of the Late Paleozoic supercontinent Pangea is the prolonged and diachronous formation of the collisional belts of the Rheic suture zone coeval with recurrent continental breakup and subsequent formation of the mid-ocean ridge systems of the Paleo- and Neo-Tethys oceans at the Devonian and Permian margins of the Gondwana plate, respectively. To decide whether these processes are causally related or not, it is necessary to accurately reconstruct the plate motion of Gondwana relative to Laurussia. Here we propose that the strain pattern preserved in the continental crust can be used for the reconstruction of ancient plate kinematics. We present Euler pole locations for the three fundamental stages of the Late Paleozoic assembly of Pangea and closure of the Rheic Ocean: (I) Early Devonian (ca. 400 Ma) collisional tectonics affected Gondwana at the Armorican Spur north of western Africa and at the promontory of the South China block/Australia of eastern Gondwana, resulting in the Variscan and the Qinling orogenies, respectively. The Euler pole of the rotational axis between Gondwana and Laurussia is positioned east of Gondwana close to Australia. (II) Continued subduction of the western Rheic Ocean initiates the clockwise rotation of Gondwana that is responsible for the separation of the South China block from Gondwana and the opening of Paleo-Tethys during the Late Devonian. The position of the rotational axis north of Africa reveals a shift of the Euler pole to the west. (III) The terminal closure of the Rheic Ocean resulted in the final tectonics of the Alleghanides, the Mauritanides and the Ouachita-Sonora-Marathon belt, occurred after the cessation of the Variscan orogeny in Central Europe, and is coeval with the formation of the Central European Extensional Province and the opening of Neo-Tethys at ca. 300 Ma. The Euler pole for the final closure of the Rheic Ocean is positioned near Oslo (Laurussia). Thus, the concomitant formation of convergent and divergent plate boundaries during the assembly of Pangea is due to the relocation of the particular rotational axis. From a geodynamic point of view, coupled collisional (western Pangea) and extensional tectonics (eastern Pangea) due to plate tectonic reorganization is fully explained by slab pull and ridge push forces.

Geochemistry and tectonostratigraphy of the basal allochthonous units of SW Iberia (Évora Massif, Portugal): Keys to the reconstruction of pre-Pangean paleogeography in southern Europe

NASA Astrophysics Data System (ADS)

Fernández, Rubén Díez; Fuenlabrada, José Manuel; Chichorro, Martim; Pereira, M. Francisco; Sánchez-Martínez, Sonia; Silva, José B.; Arenas, Ricardo

2017-01-01

The basal allochthonous units of NW and SW Iberia are members of an intra-Gondwana suture zone that spreads across the Iberian Massif and was formed during the collision of Gondwana and Laurussia in the late Paleozoic. This suture zone is made of allochthonous terranes and is currently preserved as a tectonically dismembered ensemble. A multi-proxy analysis is applied to the basal allochthonous units of Iberia to test their affinity and potential usage for tracing a suture zone. A comparison of the lithostratigraphy, tectonometamorphic evolution, geochronology, and geochemical characteristics of the Ediacaran series of these units reveals striking affinities. They derive from rather similar immature sedimentary successions, deposited along the same continental margin, and in relation to a Cadomian magmatic arc. Sm-Nd systematics indicates that the isotopic sources are among the oldest of the Iberian Massif (ca. 2.15-1.5 Ga), suggesting a very strong contribution from the West African Craton. These Ediacaran series were affected by high-P and low- to medium-T metamorphism (blueschist to eclogite facies) during the Late Devonian (ca. 370 Ma). They occur below allochthonous ophiolitic sequences, and on top of autochthonous or parautochthonous domains lacking of high-P and low- to medium-T Devonian metamorphism, i.e., tectonically sandwiched between lithosphere-scale thrusts. The combination of all these characteristics makes these particular Ediacaran series different from the rest of the terranes of the Iberian Massif. Such singularity could be useful for tracing more occurrences of the same suture zone along the Variscan orogen, particularly in cases where its preservation and recognition may be cryptic. It also contributes to improve the paleogeographic reconstruction of the margin of Gondwana during the Ediacaran.

Hinterland drainage closure and lake formation in response to middle Eocene Farallon slab removal, Nevada, U.S.A.

NASA Astrophysics Data System (ADS)

Smith, M. Elliot; Cassel, Elizabeth J.; Jicha, Brian R.; Singer, Brad S.; Canada, Andrew S.

2017-12-01

Hinterland basins can accumulate high resolution archives of orogenic processes and continental climate, but are challenging to reconstruct due to tectonic overprinting and the inherent complexity of their lithofacies assemblages. The Cordilleran hinterland of northeast Nevada has been interpreted to have overlain a flattened Farallon slab from the Late Cretaceous to Eocene. Slab removal and advection of asthenospheric mantle beneath Nevada have been invoked to explain a southwestward migrating wave of Eocene to Oligocene volcanism and proposed as a driver for topographic uplift. However, the timing of slab removal and possible subsequent delamination of North American lithospheric mantle can only ambiguously be related to the surface record. Subsequent Neogene extension and basin filling has complicated the correlation and interpretation of strata that record these events. Here we apply single crystal sanidine 40Ar/39Ar geochronology to 26 ash beds in northeast Nevada to reconstruct Paleogene geographic and hydrologic evolution. We use these ages and legacy geochronology to compare lithofacies and isotope proxy records of meteoric waters to regional tectonics and global climate, and assess competing tectonic interpretations for lake basin formation. Lakes formed locally prior to ca. 48.7 Ma in northeast Nevada, coeval with foreland lakes of the Green River Formation. The most expansive phase of lacustrine deposition resulted in onlap onto locally derived fluvial deposits and folded Paleozoic bedrock, and occurred between ca. 43.4 and ca. 40.8 Ma. Elko Formation strata exhibit a basin-wide transition from fluvial-lacustrine to fluctuating profundal lithofacies at ca. 42.7 Ma, suggesting a shift towards regional hydrologic closure. The stromatolitic upper Elko Formation is intercalated with ash fall tuffs and several partially welded to unwelded ignimbrites from increasingly proximal volcanism. Elko Formation deposition ended by ca. 40.4 Ma. 40Ar/39Ar ages for seven ash beds in the Dead Horse Formation at Copper Basin in northern Elko County indicate intermittent ash bed deposition between 45.2 Ma and 38.6 Ma, and an episode of lacustrine deposition between 39.8 Ma and 38.6 Ma that post-dates the main phase of Lake Elko. δD values of volcanic glass sampled from dated ash beds reflect changes in the hydrogen isotope compositions of local Eocene waters, and systematically vary by 80-102‰ according to their depositional environment. The Elko Formation and overlying volcanic strata are overlain regionally by a pronounced unconformity of ∼20 m.y. In the Copper Basin area, deposition continued locally into the Oligocene in the hanging wall of a ductile detachment. The geochronologic and isotopic framework presented here permits reanalysis of the Piñon Range carbonate proxy record that was previously interpreted to record both regional uplift and the middle Eocene climatic optimum. New data suggest instead that isotope values of hydration waters within the Elko Formation were strongly influenced by evaporation, and a change from lacustrine to non-lacustrine conditions can account for the δ18O shift that was interpreted to reflect regional uplift. Moreover, the end of Elko Formation deposition predated the middle Eocene climatic optimum. We interpret the overall record of drainage ponding and paleovalley inundation, progressively more evaporative lacustrine conditions, increasingly proximal volcanism, and subsequent prolonged unconformity to reflect the surface effects of progressive NE to SW removal of the Farallon slab.

Numerical modelling of edge-driven convection during rift-to-drift transition: application to the Red Sea

NASA Astrophysics Data System (ADS)

Fierro, Elisa; Capitanio, Fabio A.; Schettino, Antonio; Morena Salerno, V.

2017-04-01

We use numerical modeling to investigate the coupling of mantle instabilities and surface tectonics along lithospheric steps developing during rifting. We address whether edge driven convection (EDC) beneath rifted continental margins and shear flow during rift-drift transition can play a role in the observed post-rift compressive tectonic evolution of the divergent continental margins along the Red Sea. We run a series of 2D simulations to examine the relationship between the maximum compression and key geometrical parameters of the step beneath continental margins, such as the step height due to lithosphere thickness variation and the width of the margins, and test the effect of rheology varying temperature- and stress-dependent viscosity in the lithosphere and asthenosphere. The development of instabilities is initially illustrated as a function of these parameters, to show the controls on the lithosphere strain distribution and magnitude. We then address the transient evolution of the instabilities to characterize their duration. In an additional suite of models, we address the development of EDC during plate motions, thus accounting for the mantle shearing due to spreading. Our results show an increase of strain with the step height as well as with the margin width up to 200 km. After this value the influence of ridge margin can be neglected. Strain rates are, then, quantified for a range of laboratory-constrained constitutive laws for mantle and lithosphere forming minerals. These models propose a viable mechanism to explain the post-rift tectonic inversion observed along the Arabian continental margin and the episodic ultra-fast sea floor spreading in the central Red Sea, where the role of EDC has been invoked.

Geochemistry and geochronology of ore-bearing and barren intrusions in the Luanchuan ore fields of East Qinling metallogenic belt, China: Diverse tectonic evolution and implications for mineral exploration

NASA Astrophysics Data System (ADS)

Xue, Fei; Wang, Gongwen; Santosh, M.; Yang, Fan; Shen, Zhiwei; Kong, Liang; Guo, Nana; Zhang, Xuhuang; Jia, Wenjuan

2018-05-01

The Luanchuan ore fields form part of the East Qinling metallogenic belt in central China. In this study, we compare two ore-bearing intrusions, the Shibaogou granitic pluton (SBG) and the Zhongyuku granitic pluton (ZYK), with the ore-barren Laojunshan intrusion (LJS) from the Luanchuan ore field. Geochemically, all the three intrusions are characterized by high-Si, high-K, and alkalis, together with moderate-ASI, exhibiting I-type granite features. The rocks, especially the ore-related plutons also show enrichment in LREEs. Mineral chemistry of biotite from the intrusions exhibits similar features of high Si and Mg, and low Al and Fe. Zircon grains from the ZYK intrusion yielded a U-Pb age of 149.6 ± 2.4 Ma. The zircon grains show εHf (t) values and two stage model ages (TDM2) in the range of -16.8 to -19.7 and 1998-2156 Ma respectively. The biotite composition and Hf isotopic data indicate that the magma was derived by re-melting of deep crustal material with minor input of mantle components. We evaluate the results to understand the physico-chemical conditions, petrogenesis, and tectonic setting, and their implications for mineral exploration. The ore-bearing plutons show wide ranges of temperature and oxygen fugacity, favoring Mo-W mineralization. In addition, estimates on pressure and depth of emplacement suggest that lower solidification pressure in a decompressional setting contributed to the evolution of magmatic hydrothermal deposits. Our data suggest that the ZYK has the highest potential for Mo-W mineralization. The ore-bearing plutons of ZYK and SBG were formed in a transitional tectonic setting from compression to extension, with the large-scale metallogeny triggered by slab melts at ca. 145 Ma. However, the ore-barren LJS batholith formed in an extension-related geodynamic setting at ∼115 Ma. Our study shows that different tectonic settings and consequent physico-chemical conditions dictated the ore potential of the intrusions in the Luanchuan ore district.

Numerical modelling of instantaneous plate tectonics

NASA Technical Reports Server (NTRS)

Minster, J. B.; Haines, E.; Jordan, T. H.; Molnar, P.

1974-01-01

Assuming lithospheric plates to be rigid, 68 spreading rates, 62 fracture zones trends, and 106 earthquake slip vectors are systematically inverted to obtain a self-consistent model of instantaneous relative motions for eleven major plates. The inverse problem is linearized and solved iteratively by a maximum-likelihood procedure. Because the uncertainties in the data are small, Gaussian statistics are shown to be adequate. The use of a linear theory permits (1) the calculation of the uncertainties in the various angular velocity vectors caused by uncertainties in the data, and (2) quantitative examination of the distribution of information within the data set. The existence of a self-consistent model satisfying all the data is strong justification of the rigid plate assumption. Slow movement between North and South America is shown to be resolvable.

Elevated lateral stress in unlithified sediment, Midcontinent, United States - geotechnical and geophysical indicators for a tectonic origin

USGS Publications Warehouse

Woolery, E.W.; Schaefer, J.A.; Wang, Z.

2003-01-01

Indirect and direct geotechnical measurements revealed the presence of high lateral earth pressure (Ko) in shallow, unlithified sediment at a site in the northernmost Mississippi embayment region of the central United States. Results from pile-load and pressuremeter tests showed maximum Ko values greater than 10; however, the complex geologic environment of the Midcontinent made defining an origin for the anomalous Ko based solely on these measurements equivocal. Although in situ sediment characteristics indicated that indirect tectonic or nontectonic geologic mechanisms that include transient overburden loads (e.g., fluvial deposition/erosion, glacial advance/retreat) and dynamic shear loads (e.g., earthquakes) were not the dominant cause, they were unable to provide indicators for a direct tectonic generation. Localized stresses induced anthropogenically by the geotechnical field tests were also considered, but ruled out as the primary origin. A high-resolution shear-wave (SH) reflection image of geologic structure in the immediate vicinity of the test site revealed compression-style neotectonism, and suggested that the elevated stress was a tectonic manifestation. Post-Paleozoic reflectors exhibit a Tertiary (?) structural inversion, as evidenced by post-Cretaceous fault displacement and pronounced positive folds in the hanging wall of the interpreted faults. The latest stratigraphic extent of the stress effects (i.e., all measurements were in the Late Cretaceous to Tertiary McNairy Formation), as well as the relationship of stress orientation with the orientation of local structure and regional stress, remain unknown. These are the subjects of ongoing studies. ?? 2003 Elsevier Science B.V. All rights reserved.

Interaction Between Neuronal NOS Signaling and Temperature Influences SR Ca2+ Leak:Role of Nitroso-Redox Balance

PubMed Central

Dulce, Raul A.; Mayo, Vera; Rangel, Erika B.; Balkan, Wayne; Hare, Joshua M.

2014-01-01

Rationale While nitric oxide (NO) signaling modulates cardiac function and excitation-contraction coupling, opposing results due to inconsistent experimental conditions, particularly with respect to temperature, confound the ability to elucidate NO signaling pathways. Here we show that temperature significantly modulates NO effects. Objective Test the hypothesis that temperature profoundly impacts nitroso-redox equilibrium, thereby affecting sarcomeric reticulum (SR) Ca2+ leak. Methods and Results We measured SR Ca2+ leak in cardiomyocytes from wild-type (WT), NO/redox imbalance (NOS1−/−), and hyper S-nitrosylation (GSNOR−/−) mice. In WT cardiomyocytes, SR Ca2+ leak increased as temperature decreased from 37°C to 23°C, whereas, in NOS1−/ −cells, the leak suddenly increased when the temperature surpassed 30°C. GSNOR−/ − cardiomyocytes exhibited low leak throughout the temperature range. Exogenously added NO had a biphasic effect on NOS1−/− cardiomyocytes; reducing leak at 37°C but increasing it at sub-physiologic temperatures. Oxypurinol and Tempol diminished the leak in NOS1−/ − cardiomyocytes. Cooling from 37° to 23°C increased ROS generation in WT but decreased it in NOS1−/− cardiomyocytes. Oxypurinol further reduced ROS generation. At 23°C in WT cells, leak was decreased by tetrahydrobiopterin, an essential NOS cofactor. Cooling significantly increased SR Ca2+ content in NOS1−/− cells but had no effect in WT or GSNOR−/−. Conclusions Ca2+ leak and temperature are normally inversely proportional, whereas NOS1 deficiency reverses this effect, increasing leak and elevating ROS production as temperature increases. Reduced denitrosylation (GSNOR deficiency) eliminates the temperature dependence of leak. Thus, temperature regulates the balance between NO and ROS which in turn has a major impact on SR Ca2+. PMID:25326127

Imaging Anisotropic Layering with Bayesian Inversion of Multiple Data Types

NASA Astrophysics Data System (ADS)

Bodin, T.; Leiva, J.; Romanowicz, B. A.; Maupin, V.; Yuan, H.

2015-12-01

Anisotropic images of the upper-mantle are usually obtained by analyzing different types of seismic observables, such as surface wave dispersion curves or waveforms, SKS splitting data, or receiver functions. These different data types sample different volumes of the earth, they are sensitive to separate length-scales, and hence are associated with various levels of uncertainties. They are traditionally interpreted separately, and often result in incompatible models. We present a Bayesian inversion approach to jointly invert these different data types. Seismograms for SKS and P phases are directly inverted, thus avoiding intermediate processing steps such as numerical deconvolution or computation of splitting parameters. Probabilistic 1D profiles are obtained with a transdimensional Markov chain Monte Carlo scheme, in which the number of layers, as well as the presence or absence of anisotropy in each layer, are treated as unknown parameters. In this way, seismic anisotropy is only introduced if required by the data. The algorithm is used to resolve both isotropic and anisotropic layering down to a depth of 350 km beneath two seismic stations in North America in two different tectonic settings: the stable Canadian shield (station FFC), and the tectonically active southern Basin and Range Province (station TA-214A). In both cases, the lithosphere-asthenosphere boundary is clearly visible, and marked by a change in direction of the fast axis of anisotropy. Our study confirms that azimuthal anisotropy is a powerful tool for detecting layering in the upper mantle.

Analogue modelling on the interaction between shallow magma intrusion and a strike-slip fault: Application on the Middle Triassic Monzoni Intrusive Complex (Dolomites, Italy)

NASA Astrophysics Data System (ADS)

Michail, Maria; Coltorti, Massimo; Gianolla, Piero; Riva, Alberto; Rosenau, Matthias; Bonadiman, Costanza; Galland, Olivier; Guldstrand, Frank; Thordén Haug, Øystein; Rudolf, Michael; Schmiedel, Tobias

2017-04-01

The southwestern part of the Dolomites in Northern Italy has undergone a short-lived Ladinian (Middle Triassic) tectono-magmatic event, forming a series of significant magmatic features. These intrusive bodies deformed and metamorphosed the Permo-Triassic carbonate sedimentary framework. In this study we focus on the tectono-magmatic evolution of the shallow shoshonitic Monzoni Intrusive Complex of this Ladinian event (ca 237 Ma), covering an area of 20 km^2. This NW-SE elongated intrusive structure (5 km length) shows an orogenic magmatic affinity which is in contrast to the tectonic regime at the time of intrusion. Strain analysis shows anorogenic transtensional displacement in accordance with the ENE-WSW extensional pattern in the central Dolomites during the Ladinian. Field interpretations led to a detailed description of the regional stratigraphic sequence and the structural features of the study area. However, the geodynamic context of this magmatism and the influence of the inherited strike-slip fault on the intrusion, are still in question. To better understand the specific natural prototype and the general mechanisms of magma emplacement in tectonically active areas, we performed analogue experiments defined by, but not limited to, first order field observations. We have conducted a systematic series of experiments in different tectonic regimes (static conditions, strike-slip, transtension). We varied the ratio of viscous to brittle stresses between magma and country rock, by injecting Newtonian fluids both of high and low viscosity (i.e. silicone oil/vegetable oil) into granular materials of varying cohesion (sand, silica flour, glass beads). The evolving surface and side view of the experiments were monitored by photogrammetric techniques for strain analyses and topographic evolution. In our case, the combination of the results from field and analogue experiments brings new insights regarding the tectonic regime, the geometry of the intrusive body, and the deformational pattern of the evolving system.

Accretion and exhumation at a Variscan active margin, recorded in the Saxothuringian flysch

NASA Astrophysics Data System (ADS)

Schäfer, J.; Neuroth, H.; Ahrendt, H.; Dörr, W.; Franke, W.

The Saxothuringian flysch basin, on the north flank of the Central European Variscides, was fed and eventually overthrust by the northwestern, active margin of the Tepla-Barrandian terrane. Clast spectra, mineral composition and isotopic ages of detrital mica and zircon have been analyzed in order to constrain accretion and exhumation of rocks in the orogenic wedge. The earliest clastic sediments preserved are of early Famennian age (ca. 370Ma). They are exposed immediately to the NW of the suture, and belong to the par-autochthon of the foreland. Besides ultramafic (?ophiolite) material, these rocks contain clasts derived from Early Paleozoic continental slope sediments, originally deposited at the NW margin of the Saxothuringian basin. These findings, together with the paleogeographic position of the Famennian clastics debris on the northwestern passive margin, indicate that the Saxothuringian narrow ocean had been closed by that time. Microprobe analyses of detrital hornblendes suggest derivation from the ``Randamphibolit'' unit, now present in the middle part of the Saxothuringian allochthon (Münchberg nappes). Detrital zircons of metamorphic rocks formed a little earlier (ca. 380Ma) indicate rapid recycling at the tectonic front. The middle part of the flysch sequence (ca. early to middle Viséan), both in the par-autochthon and in the allochthon, contains abundant clasts of Paleozoic rocks derived from the northwestern slope and rise, together with debris of Cadomian basement, 500-Ma granitoids and 380Ma (early Variscan) crystalline rocks. All of these source rocks were still available in the youngest part of the flysch (c. middle to late Viséan), but some clasts record, in addition, accretion of the northwestern shelf. Our findings permit deduction of minimum rates of tectonic shortening well in excess of 10-30mm per year, and rates of exhumation of ca. 3mm/a, and possibly more.

An apparent "vital effect" of calcification rate on the Sr/Ca temperature proxy in the reef coral Montipora capitata

USGS Publications Warehouse

Kuffner, Ilsa; Jokiel, Paul L.; Rodgers, Kuulei; Andersson, Andreas; Mackenzie, Fred T.

2012-01-01

Measuring the strontium to calcium ratio in coral skeletons reveals information on seawater temperatures during skeletal deposition, but studies have shown additional variables may affect the ratio. Here we measured Sr/Ca in the reef coral, Montipora capitata, grown in six mesocosms continuously supplied with seawater from the adjacent reef flat. Three mesocosms were ambient controls, and three had seawater chemistry simulating "ocean acidification" (OA). We found that Sr/Ca was not affected by the OA treatment, and neither was coral calcification for these small colonies (larger colonies did show an OA effect). The lack of OA effects allowed us to test the hypothesis that coral growth rate can affect Sr/Ca using the natural range in calcification rates of the corals grown at the same temperature. We found that Sr/Ca was inversely related to calcification rate (Sr/Ca = 9.39 - 0.00404 mmol/mol * mg day-1 cm-2, R2 = 0.32). Using a previously published calibration curve for this species, a 22 mg day-1 colony-1 increase in calcification rate introduced a 1°C warmer temperature estimate, with the 27 corals reporting "temperatures" ranging from 24.9 to 28.9, with mean 26.6 ± 0.9°C SD. Our results lend support to hypotheses invoking kinetic processes and growth rate to explain vital effects on Sr/Ca. However, uncertainty in the slope of the regression of Sr/Ca on calcification and a low R-squared value lead us to conclude that Sr/Ca could still be a useful proxy in this species given sufficient replication or by including growth rate in the calibration.

The role of disseminated calcite in the chemical weathering of granitoid rocks

USGS Publications Warehouse

White, A.F.; Bullen, T.D.; Vivit, D.V.; Schulz, M.S.; Clow, D.W.

1999-01-01

Accessory calcite, present at concentrations between 300 and 3000 mg kg-1, occurs in fresh granitoid rocks sampled from the Merced watershed in Yosemite National Park, CA, USA; Loch Vale in Rocky Mountain National Park CO USA; the Panola watershed, GA USA; and the Rio Icacos, Puerto Rico. Calcite occurs as fillings in microfractures, as disseminated grains within the silicate matrix, and as replacement of calcic cores in plagioclase. Flow-through column experiments, using de-ionized water saturated with 0.05 atm. CO2, produced effluents from the fresh granitoid rocks that were dominated by Ca and bicarbonate and thermodynamically saturated with calcite. During reactions up to 1.7 yr, calcite dissolution progressively decreased and was superceded by steady state dissolution of silicates, principally biotite. Mass balance calculations indicate that most calcite had been removed during this time and accounted for 57-98% of the total Ca released from these rocks. Experimental effluents from surfically weathered granitoids from the same watersheds were consistently dominated by silicate dissolution. The lack of excess Ca and alkalinity indicated that calcite had been previously removed by natural weathering. The extent of Ca enrichment in watershed discharge fluxes corresponds to the amounts of calcite exposed in granitoid rocks. High Ca/Na ratios relative to plagioclase stoichiometries indicate excess Ca in the Yosemite, Loch Vale, and other alpine watersheds in the Sierra Nevada and Rocky Mountains of the western United States. This Ca enrichment correlates with strong preferential weathering of calcite relative to plagioclase in exfoliated granitoids in glaciated terrains. In contrast, Ca/Na flux ratios are comparable to or less than the Ca/Na ratios for plagioclase in the subtropical Panola and tropical Rio Icacos watersheds, in which deeply weathered regoliths exhibit concurrent losses of calcite and much larger masses of plagioclase during transport-limited weathering. These results indicate that the weathering of accessory calcite may strongly influence Ca and alkalinity fluxes from silicate rocks during and following periods of glaciation and tectonism but is much less important for older stable geomorphic surfaces.

Enhanced permeability and antifouling performance of cellulose acetate ultrafiltration membrane assisted by l-DOPA functionalized halloysite nanotubes.

PubMed

Mu, Keguang; Zhang, Dalun; Shao, Ziqiang; Qin, Dujian; Wang, Yalong; Wang, Shuo

2017-10-15

l-Dopa functionalized halloysite nanotubes (HNTs) were prepared by the self-polymerization of l-dopa in the weak alkaline condition. Then different contents of l-dopa coated HNTs (LPDHNTs) were blended into cellulose acetate to prepare enhanced performance ultrafiltration membranes via the phase inversion method. The HNTs and LPDHNTs were characterized by FTIR, XPS, and TEM anysis. And the membranes morphologies, separation performance, antifouling performance, mechanical properties and hydrophilicity were also investigated. It was found that the composite membranes exhibited excellent antifouling performance. The pure water flux of 3.0wt% LPDHNTs/CA membrane increased from 11.4Lm -2 h -1 to 92.9Lm -2 h -1 , while the EA rejection ratio of the membrane was about 91.2%. In addition, the mechanical properties of the resultant membranes were strengthened compared with the CA ultrafiltration membrane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intraplate 'typical' and Ca-rich igneous rocks associated with carbonatites in Baluchistan, Middle East

NASA Astrophysics Data System (ADS)

Romanko, Alexander

2010-05-01

Islamic republic of Iran We present some interesting materials on a poorly studied Neogene-(Quaternary) igneous rocks of Baluchistan and Sistan province, east Iran. They were received by a group led by a regional specialists E. Romanko, A. Hushmanzadeh and M.A.A. Nogol Sadat. Some important features on the rock studied are as follows: mainly K-Na subalkaline rock affinity (also alkaline one too) with a middle K), not very High-Ti, not high, deep 87Sr/86Sr (ISr) = 0.7039 +/- 2 (trachyandesite) and 0.7049 +/- 3 (trachybasalt, both data by GIN RAS, Russia) alongside the 0.7049 on a vulcanite (Camp & Griffis, 1982), LREE-enrichment with a high LREE/HREE (La - more than 32 ppm), and a characteristical Eu/Eu* more than 1.1; up to high - 1/3 of CaO and up to a high - 0.45% of Sr in basic trachyandesites (meaning the real carbonatites ca 200 km to the east, Hanneshin, Afghanistan), complex correlation of some characteristical elements; then-High-Ti (rhutile, Ti-hornblende) and High-Ca phases (clinocoizite, also, Ca- rich ceolie - vayrakite is proposed), replacement of primary minerals due to a fairly strong rock-fluid interaction. North-East tectonic-magmatic +/- metallogenic (economic regional Cu-Au +/- Pb, Zn, poor Ag, PGE, As, Hg, Bi etc. - e.x., Anarak deposits (E.Romanko, 1984) ) zonation, related to the famous subduction of Arabian plate, exists, e.x. (calc-alkaline /1/ - intraplate /2/ ): 1: Eocene shoshonites - Paleocene-Oligocene calc-alkaline intrusives - Miocene-Recent calc-alkaline volcanic (-plutonic) rocks and 2: Paleogene? (Lut block)-Neogene subalkaline rocks - Quaternary Afghanistan carbonatites etc. Alpine compression on the moderate subductional depths up to 200 km (Trubitsin et al., 2004) in the Central Iran, at least, partly compensated, as proposed, by contemporaneous/ younger Pg?-N-Q extensional intraplate magmatism of the East Iran/ Afghanistan and nearby area.

Preliminary result of P-wave speed tomography beneath North Sumatera region

NASA Astrophysics Data System (ADS)

Jatnika, Jajat; Nugraha, Andri Dian; Wandono

2015-04-01

The structure of P-wave speed beneath the North Sumatra region was determined using P-wave arrival times compiled by MCGA from time periods of January 2009 to December 2012 combining with PASSCAL data for February to May 1995. In total, there are 2,246 local earthquake events with 10,666 P-wave phases from 63 stations seismic around the study area. Ray tracing to estimate travel time from source to receiver in this study by applying pseudo-bending method while the damped LSQR method was used for the tomographic inversion. Based on assessment of ray coverage, earthquakes and stations distribution, horizontal grid nodes was set up of 30×30 km2 for inside the study area and 80×80 km2 for outside the study area. The tomographic inversion results show low Vp anomaly beneath Toba caldera complex region and around the Sumatra Fault Zones (SFZ). These features are consistent with previous study. The low Vp anomaly beneath Toba caldera complex are observed around Mt. Pusuk Bukit at depths of 5 km down to 100 km. The interpretation is these anomalies may be associated with ascending hot materials from subduction processes at depths of 80 km down to 100 km. The obtained Vp structure from local tomography will give valuable information to enhance understanding of tectonic and volcanic in this study area.

Preliminary result of P-wave speed tomography beneath North Sumatera region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jatnika, Jajat; Indonesian Meteorological, Climatological and Geophysical Agency; Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id

2015-04-24

The structure of P-wave speed beneath the North Sumatra region was determined using P-wave arrival times compiled by MCGA from time periods of January 2009 to December 2012 combining with PASSCAL data for February to May 1995. In total, there are 2,246 local earthquake events with 10,666 P-wave phases from 63 stations seismic around the study area. Ray tracing to estimate travel time from source to receiver in this study by applying pseudo-bending method while the damped LSQR method was used for the tomographic inversion. Based on assessment of ray coverage, earthquakes and stations distribution, horizontal grid nodes was setmore » up of 30×30 km2 for inside the study area and 80×80 km2 for outside the study area. The tomographic inversion results show low Vp anomaly beneath Toba caldera complex region and around the Sumatra Fault Zones (SFZ). These features are consistent with previous study. The low Vp anomaly beneath Toba caldera complex are observed around Mt. Pusuk Bukit at depths of 5 km down to 100 km. The interpretation is these anomalies may be associated with ascending hot materials from subduction processes at depths of 80 km down to 100 km. The obtained Vp structure from local tomography will give valuable information to enhance understanding of tectonic and volcanic in this study area.« less

Dynamic response to strike-slip tectonic control on the deposition and evolution of the Baranof Fan, Gulf of Alaska

USGS Publications Warehouse

Walton, Maureen A. L.; Gulick, Sean P. S.; Reece, Robert S.; Barth, Ginger A.; Christeson, Gail L.; VanAvendonk, Harm J.

2014-01-01

The Baranof Fan is one of three large deep-sea fans in the Gulf of Alaska, and is a key component in understanding large-scale erosion and sedimentation patterns for southeast Alaska and western Canada. We integrate new and existing seismic reflection profiles to provide new constraints on the Baranof Fan area, geometry, volume, and channel development. We estimate the fan’s area and total sediment volume to be ∼323,000 km2 and ∼301,000 km3, respectively, making it among the largest deep-sea fans in the world. We show that the Baranof Fan consists of channel-levee deposits from at least three distinct aggradational channel systems: the currently active Horizon and Mukluk channels, and the waning system we call the Baranof channel. The oldest sedimentary deposits are in the northern fan, and the youngest deposits at the fan’s southern extent; in addition, the channels seem to avulse southward consistently through time. We suggest that Baranof Fan sediment is sourced from the Coast Mountains in southeastern Alaska, transported offshore most recently via fjord to glacial sea valley conduits. Because of the translation of the Pacific plate northwest past sediment sources on the North American plate along the Queen Charlotte strike-slip fault, we suggest that new channel formation, channel beheadings, and southward-migrating channel avulsions have been influenced by regional tectonics. Using a simplified tectonic reconstruction assuming a constant Pacific plate motion of 4.4 cm/yr, we estimate that Baranof Fan deposition initiated ca. 7 Ma.

Understanding the Tectonic Features in the South China Sea By Analyzing Magnetic Anomalies

NASA Astrophysics Data System (ADS)

Guo, L.; Meng, X.; Shi, L.; Yao, C.

2011-12-01

The South China Sea (SCS) is surrounded by the Eurasia, Pacific and India-Australia plates. It formed during Late Oligocene-Early Miocene, and is one of the largest marginal seas in the Western Pacific. The collision of Indian subcontinent and Eurasian plate in the northwest, back-arc spreading in the centre and subduction beneath the Philippine plate along Manila trench in the east and along Palawan trough in the south had produced the complex tectonic features in the SCS that we can see today. In the past few decades, a variety of geophysical methods were conducted to study geological tectonics and evolution of the SCS. Here, we analyzed the magnetic data of this area using new data enhancement techniques to understand the regional tectonic features. We assembled the magnetic anomalies data with a resolution of two arc-minute from the World Digital Magnetic Anomaly Map, and then gridded the data on a regular grid. Then we used the method of reduction to the pole at low latitude with varying magnetic inclinations to stably reduce the magnetic anomalies. Then we used the preferential continuation method based on Wiener filtering and Green's equivalence principle to separate the reduced-to-pole (RTP) magnetic anomalies, and subsequently analyze the regional and residual anomalies. We also calculated the directional horizontal derivatives and the tilt-angle derivative of the data to derive clearer geological structures with more details. Then we calculated the depth of the magnetic basement surface in the area by 3D interface inversion. From the results of the preliminary processing, we analyzed the main faults, geological structures, magma distribution and tectonic features in the SCS. In the future, the integrated interpretation of the RTP magnetic anomalies, Bouguer gravity anomalies and other geophysical methods will be performed for better understanding the deep structure , the tectonic features and evolution of the South China Sea. Acknowledgment: We acknowledge the financial support of the SinoProbe project (201011039), the Fundamental Research Funds for the Central Universities (2010ZY26, 2011PY0184), and the National Natural Science Foundation of China (40904033, 41074095).

A 3D resistivity model derived from the transient electromagnetic data observed on the Araba fault, Jordan

NASA Astrophysics Data System (ADS)

Rödder, A.; Tezkan, B.

2013-01-01

72 inloop transient electromagnetic soundings were carried out on two 2 km long profiles perpendicular and two 1 km and two 500 m long profiles parallel to the strike direction of the Araba fault in Jordan which is the southern part of the Dead Sea transform fault indicating the boundary between the African and Arabian continental plates. The distance between the stations was on average 50 m. The late time apparent resistivities derived from the induced voltages show clear differences between the stations located at the eastern and at the western part of the Araba fault. The fault appears as a boundary between the resistive western (ca. 100 Ωm) and the conductive eastern part (ca. 10 Ωm) of the survey area. On profiles parallel to the strike late time apparent resistivities were almost constant as well in the time dependence as in lateral extension at different stations, indicating a 2D resistivity structure of the investigated area. After having been processed, the data were interpreted by conventional 1D Occam and Marquardt inversion. The study using 2D synthetic model data showed, however, that 1D inversions of stations close to the fault resulted in fictitious layers in the subsurface thus producing large interpretation errors. Therefore, the data were interpreted by a 2D forward resistivity modeling which was then extended to a 3D resistivity model. This 3D model explains satisfactorily the time dependences of the observed transients at nearly all stations.

A moment-tensor catalog for intermediate magnitude earthquakes in Mexico

NASA Astrophysics Data System (ADS)

Rodríguez Cardozo, Félix; Hjörleifsdóttir, Vala; Martínez-Peláez, Liliana; Franco, Sara; Iglesias Mendoza, Arturo

2016-04-01

Located among five tectonic plates, Mexico is one of the world's most seismically active regions. The earthquake focal mechanisms provide important information on the active tectonics. A widespread technique for estimating the earthquake magnitud and focal mechanism is the inversion for the moment tensor, obtained by minimizing a misfit function that estimates the difference between synthetic and observed seismograms. An important element in the estimation of the moment tensor is an appropriate velocity model, which allows for the calculation of accurate Green's Functions so that the differences between observed and synthetics seismograms are due to the source of the earthquake rather than the velocity model. However, calculating accurate synthetic seismograms gets progressively more difficult as the magnitude of the earthquakes decreases. Large earthquakes (M>5.0) excite waves of longer periods that interact weakly with lateral heterogeneities in the crust. For these events, using 1D velocity models to compute Greens functions works well and they are well characterized by seismic moment tensors reported in global catalogs (eg. USGS fast moment tensor solutions and GCMT). The opposite occurs for small and intermediate sized events, where the relatively shorter periods excited interact strongly with lateral heterogeneities in the crust and upper mantle. To accurately model the Green's functions for the smaller events in a large heterogeneous area, requires 3D or regionalized 1D models. To obtain a rapid estimate of earthquake magnitude, the National Seismological Survey in Mexico (Servicio Sismológico Nacional, SSN) automatically calculates seismic moment tensors for events in the Mexican Territory (Franco et al., 2002; Nolasco-Carteño, 2006). However, for intermediate-magnitude and small earthquakes the signal-to-noise ratio could is low for many of the seismic stations, and without careful selection and filtering of the data, obtaining a stable focal mechanism is difficult. The selection of data windows and filter parameters is tedious without a tool that allows easy viewing of the data prior to the inversion. Therefore, we developed a graphical user interface (GUI), based on Python and the python library ObsPy, that processes in a iterative and interactive way observed and synthetic seismograms prior to the inversion. The processing includes filtering, choosing and discarding traces and manual adjustment of time windows in which synthetics and observed seismograms will be compared. We calculate the Green Functions using the SPECFEM3D_GLOBE algorithm (Komatitsch et al.,2004) which employs a velocity model that is composed of a mantle and a crustal model, S362ANI (Kustowski et al., 2008) and CRUST2.0 (Bassin et al., 2000), respectively. We invert the observed seismograms for the seismic moment tensor using a method developed for earthquakes in California (Liu et al., 2004) and implemented for earthquakes in Mexico (De la Vega, 2014). In this work, we introduce the GUI, the inversion method and the results from the moment-tensor inversions obtained for intermediate-magnitude earthquakes (4.5

Structure and properties of CaMnO3/SrMnO3/BaMnO3 superlattices from first principles

NASA Astrophysics Data System (ADS)

Li, Shen; Oh, Seongshik; Rabe, Karin

2008-03-01

Previous theoretical and experimental studies have shown that three-component, or ``tri-color'' superlattices can exhibit intrinsic electric polarization due to inversion-symmetry breaking in the layer sequence. In ferromagnetic inversion-symmetry-breaking superlattices, controlled symmetry lowering is similarly expected to lead to interesting new and tunable properties. Here, we present results of first-principles density-functional-theory calculations for short-period CaMnO3/SrMnO3/BaMnO3 superlattices, using VASP. The ground state structure, magnetic ordering, polarization and dielectric response will be presented. The role of epitaxial strain in the individual layers and the role of layer sequence will be explored. Connections to experimental studies and prospects for future work will be discussed.

Seismic Surveillance. Nuclear Test Ban Verification

DTIC Science & Technology

1990-02-26

e.g., see Matthews and Cheadle, 1986). To summarize, data processing tied to 8 msec sampling is a bit coarse for the sedimentary column but...Continental Extensional Tectonics. Geological Society Special Publication No. 28, 53-65. Matthews , D.H. and Cheadle, M.J. 1986: Deep Reflections from the...Laboratory P. 0. Box 73 P.O. Box 1620 Lexington, MA 02173-0073 (3 copies) La Jolla, CA 92038-1620 Prof Fred K. Lamb Prof. William Menke University of

Localization of holes near charged defects in orbitally degenerate, doped Mott insulators

NASA Astrophysics Data System (ADS)

Avella, Adolfo; Oleś, Andrzej M.; Horsch, Peter

2018-05-01

We study the role of charged defects, disorder and electron-electron (e-e) interactions in a multiband model for t2g electrons in vanadium perovskites R1-xCaxVO3 (R = La,…,Y). By means of unrestricted Hartree-Fock calculations, we find that the atomic multiplet structure persists up to 50% Ca doping. Using the inverse participation number, we explore the degree of localization and its doping dependence for all electronic states. The observation of strongly localized wave functions is consistent with our conjecture that doped holes form spin-orbital polarons that are strongly bound to the charged Ca2+ defects. Interestingly, the long-range e-e interactions lead to a discontinuity in the wave function size across the chemical potential, where the electron removal states are more localized than the addition states.

U-Pb Geochronology of Grandite Skarn Garnet: Case Studies From Jurassic Skarns of California

NASA Astrophysics Data System (ADS)

Gevedon, M. L.; Seman, S.; Barnes, J.; Stockli, D. F.; Lackey, J. S.

2016-12-01

We present 3 case studies using a new method for U-Pb dating grossular-andradite (grandite) skarn garnet via LA-ICP-MS (Seman et al., in prep). Grandite is commonly rich in U, with high Fe3+ contents generally correlating with higher U concentrations. Micron-scale non-radiogenic Pb heterogeneities allow for regression of age data using Tera-Wasserberg concordia. Although others have dated accessory skarn minerals, garnet U-Pb ages are powerful because garnet grows early and is nearly ubiquitous in skarns, resists alteration, and provides a formation age independent of that of the causative pluton. The Darwin stock (Argus range, eastern CA) was likely a short-lived, single pulse of magmatism, genetically related to the Darwin skarn. A robust skarn garnet U-Pb age of 176.8 ± 1.3 Ma agrees well with the pluton U-Pb zircon age of 175 Ma (Chen and Moore, 1982). Furthermore, zircon separated from, and in textural equilibrium with, exoskarn garnetite yields a U-Pb age of 176.8 ± 1 Ma. Such agreement between plutonic and skarn zircon ages with a skarn garnet age in a geologically simple field area is the ideal scenario for establishing grandite U-Pb as a viable tool for directly dating skarns. The Black Rock skarn (BRS; eastern CA) is more complex: multiple plutons and ambiguous field relations complicate determination of a causative pluton. A skarn garnet U-Pb age of 172.0 ± 3 Ma confirms a middle Jurassic BRS formation age. Investigation of 4 local plutons yield zircon U-Pb ages of 222 ± 3 Ma, 213 ± 4 Ma, 207 ± 4 Ma and 176.2 ± 2 Ma. Comparison of the skarn garnet U-Pb and pluton ages suggest the BRS is genetically related to the youngest pluton, providing basis for further field and geochemical investigation. The Whitehorse skarn (WS; Mojave Desert, CA) lies in an important region for studying the changing tectono-magmatic regime of the Jurassic North American Cordillera; basin fill suggests a tectonically-controlled oscillating regional shoreline (Busby, 2012). Values of δ18O of WS garnet are strongly negative, —9.8‰ to 1.2‰, and can only be the result of access to meteoric water. A grandite U-Pb age of 162.3 ± 2 Ma requires the region of the WS not be submerged below the sea at this time. Future work coupling grandite U-Pb and δ18O may be vital in establishing the timing of Jurassic Cordilleran tectonic changes in the Mojave Desert.

Study on Seismogenesis of 2013 Ms5.1 Badong Earthquake in the Three Gorges Reservoir Region

NASA Astrophysics Data System (ADS)

Li, X.; Zeng, Z.; Xu, S.; He, C.

2015-12-01

On 16 December, 2013, an earthquake of Ms5.1 occurred in Badong County, the Three Gorges Reservoir area, China. We collected all the 150 published focal mechanism solutions (FMS) and inversed the tectonic stress field in Badong, the Three Gorges Dam and Huangling anticline area using the software SATSI (Hardebeck and Michael, 2006). Inversion results show that the orientations of maximum principle stress axis (σ1) in Badong plunge to NNE or SSW. Detailed characteristics of the stress field indicate that the σ1 axis is almost vertical in the center of Huangling anticline and turns horizontal to the west. As to deep structures, we studied the satellite gravity anomalies of 8-638 order in this area using the EIGEN-6C2 model provided by ICGRM. Combining the seismic sounding profile through the epicenter of Badong earthquake and the petrology data, we reinterpreted the deep structure in the study area. The results show that the deep crust in Badong is unstable and the deep material's upwelling leads to Huangling anticline continued uplifting, which is consistent with the result indicated from the stress filed. Both of them provide energy for the preparation of earthquake. The FMS shows that Gaoqiao Fault is the causative fault of this Ms5.1 earthquake. Field investigations indicated that the lithology and fracture characteristic in Badong is beneficial to reservoir water infiltration. Before the earthquake, reservoir water level raised to 175m, the highest storage level, which increased the loading. Based on above researches, we believe that the Ms5.1 Badong earthquake is controlled by deep tectonic environment and stress field in shallow crust. The reservoir water infiltration and uploading increase generated by water storage of the Three Gorges area reduced the strength of Gaoqiao Fault and changed its stress state. These factors jointly promoted an abrupt movement of the fault in the critical stress state, and triggered the Ms5.1 Badong earthquake.

Focal mechanisms and tidal modulation for tectonic tremors in Taiwan

NASA Astrophysics Data System (ADS)

Ide, S.; Yabe, S.; Tai, H. J.; Chen, K. H.

2015-12-01

Tectonic tremors in Taiwan have been discovered beneath the southern Central Range, but their hosting structure has been unknown. Here we constrain the focal mechanism of underground deformation related to tremors, using moment tensor inversion in the very low frequency band and tidal stress analysis. Three types of seismic data are used for two analysis steps: detection of tremors and the moment tensor inversion. Short-period seismograms from CWBSN are used for tremor detection. Broadband seismograms from BATS and the TAIGER project are used for both steps. About 1000 tremors were detected using an envelope correlation method in the high frequency band (2-8 Hz). Broadband seismograms are stacked relative to the tremor timing, and inverted for a moment tensor in the low frequency band (0.02-0.05 Hz). The best solution was obtained at 32 km depth, as a double-couple consistent with a low-angle thrust fault dipping to the east-southeast, or a high-angle thrust with a south-southwest strike. Almost all tremors occur when tidal shear stress is positive and normal stress is negative (clamping). Since the clamping stress is high for a high-angle thrust fault, the low-angle thrust fault is more likely to be the fault plane. Tremor rate increases non-linearly with increasing shear stress, suggesting a velocity strengthening friction law. The high tidal sensitivity is inconsistent with horizontal slip motion suggested by previous studies, and normal faults that dominates regional shallow earthquakes. Our results favor thrust slip on a low-angle fault dipping to the east-southeast, consistent with the subduction of the Eurasian plate. The tremor region is characterized by a deep thermal anomaly with decrease normal stress. This region has also experienced enough subduction to produce metamorphic fluids. A large amount of fluid and low vertical stress may explain the high tidal sensitivity.

The Application of COMSOL Multiphysics Package on the Modelling of Complex 3-D Lithospheric Electrical Resistivity Structures - A Case Study from the Proterozoic Orogenic belt within the North China Craton

NASA Astrophysics Data System (ADS)

Guo, L.; Yin, Y.; Deng, M.; Guo, L.; Yan, J.

2017-12-01

At present, most magnetotelluric (MT) forward modelling and inversion codes are based on finite difference method. But its structured mesh gridding cannot be well adapted for the conditions with arbitrary topography or complex tectonic structures. By contrast, the finite element method is more accurate in calculating complex and irregular 3-D region and has lower requirement of function smoothness. However, the complexity of mesh gridding and limitation of computer capacity has been affecting its application. COMSOL Multiphysics is a cross-platform finite element analysis, solver and multiphysics full-coupling simulation software. It achieves highly accurate numerical simulations with high computational performance and outstanding multi-field bi-directional coupling analysis capability. In addition, its AC/DC and RF module can be used to easily calculate the electromagnetic responses of complex geological structures. Using the adaptive unstructured grid, the calculation is much faster. In order to improve the discretization technique of computing area, we use the combination of Matlab and COMSOL Multiphysics to establish a general procedure for calculating the MT responses for arbitrary resistivity models. The calculated responses include the surface electric and magnetic field components, impedance components, magnetic transfer functions and phase tensors. Then, the reliability of this procedure is certificated by 1-D, 2-D and 3-D and anisotropic forward modeling tests. Finally, we establish the 3-D lithospheric resistivity model for the Proterozoic Wutai-Hengshan Mts. within the North China Craton by fitting the real MT data collected there. The reliability of the model is also verified by induced vectors and phase tensors. Our model shows more details and better resolution, compared with the previously published 3-D model based on the finite difference method. In conclusion, COMSOL Multiphysics package is suitable for modeling the 3-D lithospheric resistivity structures under complex tectonic deformation backgrounds, which could be a good complement to the existing finite-difference inversion algorithms.

Cluster Chemistry in Electron-Poor Ae-Pt-Cd Systems (Ae=Ca, Sr, Ba): (Sr,Ba)Pt2Cd4, Ca6Pt8Cd16, and Its Known Antitype Er6Pd16Sb8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samal, Saroj L.; Gulo, Fakhili; Corbett, John D.

Three new ternary polar intermetallic compounds, cubic Ca6Pt8Cd16, and tetragonal (Sr, Ba)Pt2Cd4 have been discovered during explorations of the Ae–Pt–Cd systems. Cubic Ca6Pt8Cd16 (Fm-3m, Z = 4, a = 13.513(1) Å) contains a 3D array of separate Cd8 tetrahedral stars (TS) that are both face capped along the axes and diagonally bridged by Pt atoms to generate the 3D anionic network Cd8[Pt(1)]6/2[Pt(2)]4/8. The complementary cationic surface of the cell consists of a face-centered cube of Pt(3)@Ca6 octahedra. This structure is an ordered ternary variant of Sc11Ir4 (Sc6Ir8Sc16), a stuffed version of the close relative Na6Au7Cd16, and a network inverse ofmore » the recent Er6Sb8Pd16 (compare Ca6Pt8Cd16). The three groups of elements each occur in only one structural version. The new AePt2Cd4, Ae = Sr, Ba, are tetragonal (P42/mnm,Z = 2, a ≈ 8.30 Å, c ≈ 4.47 Å) and contain chains of edge-sharing Cd4 tetrahedra along c that are bridged by four-bonded Ba/Sr. LMTO-ASA and ICOHP calculation results and comparisons show that the major bonding (Hamilton) populations in Ca6Pt8Cd16 and Er6Sb8Pd16 come from polar Pt–Cd and Pd–Sb interactions, that Pt exhibits larger relativistic contributions than Pd, that characteristic size and orbital differences are most evident for Sb 5s, Pt8, and Pd16, and that some terms remain incomparable, Ca–Cd versus Er–Pd.« less

Estimation of ligament strains and joint moments in the ankle during a supination sprain injury.

PubMed

Wei, Feng; Fong, Daniel Tik-Pui; Chan, Kai-Ming; Haut, Roger C

2015-01-01

This study presents the ankle ligament strains and ankle joint moments during an accidental injury event diagnosed as a grade I anterior talofibular ligament (ATaFL) sprain. A male athlete accidentally sprained his ankle while performing a cutting motion in a laboratory setting. The kinematic data were input to a three-dimensional rigid-body foot model for simulation analyses. Maximum strains in 20 ligaments were evaluated in simulations that investigated various combinations of the reported ankle joint motions. Temporal strains in the ATaFL and the calcaneofibular ligament (CaFL) were then compared and the three-dimensional ankle joint moments were evaluated from the model. The ATaFL and CaFL were highly strained when the inversion motion was simulated (10% for ATaFL and 12% for CaFL). These ligament strains were increased significantly when either or both plantarflexion and internal rotation motions were added in a temporal fashion (up to 20% for ATaFL and 16% for CaFL). Interestingly, at the time strain peaked in the ATaFL, the plantarflexion angle was not large but apparently important. This computational simulation study suggested that an inversion moment of approximately 23 N m plus an internal rotation moment of approximately 11 N m and a small plantarflexion moment may have generated a strain of 15-20% in the ATaFL to produce a grade I ligament injury in the athlete's ankle. This injury simulation study exhibited the potentially important roles of plantarflexion and internal rotation, when combined with a large inversion motion, to produce a grade I ATaFL injury in the ankle of this athlete.

Structure and evolution of a rocksalt-mudrock-tectonite: The haselgebirge in the Northern Calcareous Alps

PubMed Central

Leitner, Christoph; Neubauer, Franz; Urai, János L.; Schoenherr, Johannes

2011-01-01

The Northern Calcareous Alps are part of the Eastern Alps in Austria and Germany. The Mesozoic units of this fold-and-thrust belt were detached, thrusted and stacked along the evaporitic Haselgebirge Formation. Exposed in salt mines, rocksalt and mudrock form a two component tectonite: The rock type “haselgebirge” consists of 10–70 wt % halite with silt- to gravel- or block-sized components within a halite matrix, and the “kerngebirge” with >70 wt % halite. All rock types studied are fault rocks. By use of a temperature-independent subgrain size piezometer, the paleo-differential stress of halite was calculated at ca. 2.5 MPa in Altaussee and ca. 4.5 MPa in Berchtesgaden. Including data from a grain-size piezometer, temperatures were estimated at ca. 150 ± 20 °C and 110 ± 10 °C. This implies very high strain rates, which are about 10−10–10−9 s−1. During the tectonic movement, the halite deformed, recrystallized, and crystallized as veins in mudrock fractures. We interpret high overpressure of the pore fluid to have significantly contributed to fracturing of the mudrock. PMID:26523077

Tectonic and magmatic evolution of the northwestern Basin and Range and its transition to unextended volcanic plateaus: Black Rock Range, Nevada

USGS Publications Warehouse

Lerch, D.W.; Miller, E.; McWilliams, M.; Colgan, J.

2008-01-01

The seismically active eastern and western margins of the northern Basin and Range have been extensively studied, yet the northwestern margin of the province remains incompletely understood. The Black Rock Range of northwestern Nevada straddles the transition from the Basin and Range province to the south and east, and flat-lying volcanic plateaus to the west. This poorly understood range preserves a remarkably complete record of Cenozoic magmatism and provides an important window into the pre-Miocene history of the unextended volcanic plateaus of northeastern California and southern Oregon. Geologic mapping and 40Ar/39Ar geochronology from the northern Black Rock Range document three significant episodes of Eocene to middle Miocene volcanism. Eocene (35 Ma) basalts directly overlie Mesozoic granites and arc-related volcanic and sedimentary rocks. Locally erupted Oligocene to early Miocene (27-21 Ma) bimodal volcanic rocks comprise the bulk of the Cenozoic section and conformably overlie the Eocene basalt flows. These bimodal units include rhyolitic lavas, variably welded rhyolitic ash flows, unwelded ash-fall deposits, and thin basalt flows. In the neighboring Pine Forest Range ???20 km to the north, similar Oligocene to early Miocene units are overlain by more than 500 m of ca. 16.4 Ma Steens-equivalent basalt flows and are capped by ca. 16 Ma rhyolitic ash-flow tuffs. In the northern Black Rock Range, the ca. 16.4 Ma middle Miocene basalts are absent from the section, and a 16.2 Ma rhyolitic ash-flow tuff directly overlies the early Miocene flows. Basaltic and rhyolitic volcanic products in the northern Black Rock Range span 35-16 Ma, with many of the Oligocene volcanic units derived from local vents and dikes. Despite the map-scale complexities of locally derived lava flows, the Cenozoic section is broadly conformable and dips gently (???5??-10??) to the northwest. The region experienced no significant tilting between 35 and 16 Ma, with moderate tilting (???5??-10??) and concomitant uplift occurring after 16 Ma. This tectonic history is consistent with that of the nearby Pine Forest and Santa Rosa Ranges, where low-temperature thermochronology documents footwall exhumation along the range-bounding normal faults after 12 Ma. The velocity structure of the crust beneath the northern Black Rock Range is constrained by a recent geophysical survey (seismic reflection, refraction, and gravity) and contains gradients that correspond to basin depths predicted by our geologic mapping. Together with recently completed geological and geophysical studies from the surrounding region, our results suggest that the evolution of the northwestern margin of the Basin and Range was characterized by long-lived and voluminous volcanism without significant tectonism, followed by low-magnitude (???20%) extension along high-angle normal faults. ?? 2008 Geological Society of America.

Silicon and Manganese Partition Between Slag and Metal Phases and Their Activities Pertinent to Ferromanganese and Silicomanganese Production

NASA Astrophysics Data System (ADS)

Cengizler, Hakan; Eric, R. Hurman

Equilibrium between MnO-CaO-MgO-SiO2-Al2O3 slags and carbon saturated Mn-Si-Fe-C alloys was investigated under CO at 1500oC. Manganese and silicon activities were obtained by using the present data and the previously determined MnO and SiO2 activities of the slag. Quadratic multi-coefficient regression equations were developed for activity coefficients of manganese and silicon. The conclusions of this work are:(i)increase in the basicity and the CaO/Al2O3 ratios decreases the Mn distribution ratio,(ii)increase in the silica concentration and the MgO/CaO ratio increases the Mn distribution ratio, iii)carbon and manganese as well as carbon and silicon of the metal phase are inversely proportional,(iv)as Mn/Fe and Mn/Si ratio increases in the metal the carbon solubility increases,(v)decrease in the basicity increases the silicon content of the metal and (vi)increase in the silica content of the slag increases the silicon content of the metal and this effect is more pronounced at the higher Mn/Fe and Mn/Si ratios.

Automated measurement of hippocampal subfields in PTSD: Evidence for smaller dentate gyrus volume.

PubMed

Hayes, Jasmeet P; Hayes, Scott; Miller, Danielle R; Lafleche, Ginette; Logue, Mark W; Verfaellie, Mieke

2017-12-01

Smaller hippocampal volume has been consistently observed as a biomarker of posttraumatic stress disorder (PTSD). However, less is known about individual volumes of the subfields composing the hippocampus such as the dentate gyrus and cornu ammonis (CA) fields 1-4 in PTSD. The aim of the present study was to examine the hypothesis that volume of the dentate gyrus, a region putatively involved in distinctive encoding of similar events, is smaller in individuals with PTSD versus trauma-exposed controls. Ninety-seven recent war veterans underwent structural imaging on a 3T scanner and were assessed for PTSD using the Clinician-Administered PTSD Scale. The hippocampal subfield automated segmentation program available through FreeSurfer was used to segment the CA4/dentate gyrus, CA1, CA2/3, presubiculum, and subiculum of the hippocampus. Results showed that CA4/dentate gyrus subfield volume was significantly smaller in veterans with PTSD and scaled inversely with PTSD symptom severity. These results support the view that dentate gyrus abnormalities are associated with symptoms of PTSD, although additional evidence is necessary to determine whether these abnormalities underlie fear generalization and other memory alterations in PTSD. Published by Elsevier Ltd.

Constraints on fault and crustal strength of the Main Ethiopian Rift from formal inversion of earthquake focal mechanism data

NASA Astrophysics Data System (ADS)

Muluneh, Ameha A.; Kidane, Tesfaye; Corti, Giacomo; Keir, Derek

2018-04-01

We evaluate the frictional strength of seismogenic faults in the Main Ethiopian Rift (MER) by inverting the available, well-constrained earthquake focal mechanisms. The regional stress field is given by - 119.6°/77.2°, 6.2°/7.6°, and 97.5°/10.2° for trend/plunge of σ1, σ2 and σ3, respectively agrees well with previous fault kinematic and focal mechanism inversions. We determine the coefficient of friction, μ, for 44 seismogenic faults by assuming the pore pressure to be at hydrostatic conditions. Slip on 36 seismogenic faults occurs with μ ≥ 0.4. Slip on the remaining eight faults is possible with low μ. In general, the coefficient of friction in the MER is compatible with a value of μ of 0.59 ± 0.16 (2σ standard deviation). The shear stresses range from 16 to 129 MPa, is similar to crustal shear stress observed in extensional tectonic regimes and global compilations of shear stresses from major fault zones. The maximum shear stress is observed in the ductile crust, below the seismologically determined brittle-ductile transition (BDT) zone. Below the BDT, the crust is assumed to be weak due to thermal modification and/or high pore fluid pressure. Our results indicate linearly increasing μ and shear stress with depth. We argue that in the MER upper crust is strong and deforms according to Coulomb frictional-failure criterion.

Stress pattern of the Shanxi rift system, North China, inferred from the inversion of new focal mechanisms

NASA Astrophysics Data System (ADS)

Li, Bin; Atakan, Kuvvet; Sørensen, Mathilde Bøttger; Havskov, Jens

2015-05-01

Earthquake focal mechanisms of the Shanxi rift system, North China, are investigated for the time period 1965-April 2014. A total of 143 focal mechanisms of ML ≥ 3.0 earthquakes were compiled. Among them, 105 solutions are newly determined in this study by combining the P-wave first motions and full waveform inversion, and 38 solutions are from available published data. Stress tensor inversion was then performed based on the new database. The results show that most solutions in the Shanxi rift system exhibit normal or strike-slip faulting, and the regional stress field is transtensional and dominated by NNW-SSE extension. This correlates well with results from GPS data, geological field observations and levelling measurements across the faults. Heterogeneity exists in the regional stress field, as indicated by individual stress tensor inversions conducted for five subzones. While the minimum stress axis (σ3) appears to be consistent and stable, the orientations, especially the plunges, of the maximum and intermediate stresses (σ1 and σ2) vary significantly along the strike of the different subzones. Based on our results and combining multidisciplinary observations from geological surveys, GPS and cross-fault monitoring, a kinematic model is proposed for the Shanxi rift system, in which the rift is situated between two opposite rotating crustal blocks, exhibiting a transtensional stress regimes. This model illustrates the present-day stress field and its correlation to the regional tectonics, as well as the current crustal deformation of the Shanxi rift system. Results obtained in this study, may help to understand the geodynamics, neotectonic activity, active seismicity and potential seismic hazard in this region.

Geophysical setting of the Wabash Valley fault system

USGS Publications Warehouse

Hildenbrand, T.G.; Ravat, D.

1997-01-01

Interpretation of existing regional magnetic and gravity data and new local high-resolution aeromagnetic data provides new insights on the tectonic history and structural development of the Wabash Valley Fault System in Illinois and Indiana. Enhancement of short-wavelength magnetic anomalies reveal numerous NW- to NNE-trending ultramafic dikes and six intrusive complexes (including those at Hicks Dome and Omaha Dome). Inversion models indicate that the interpreted dikes are narrow (???3 m), lie at shallow depths (500 km long and generally >50 km wide) and with deep basins (locally >3 km thick), the ancestral Wabash Valley faults express, in comparison, minor tectonic structures and probably do not represent a failed rift arm. There is a lack of any obvious relation between the Wabash Valley Fault System and the epicenters of historic and prehistoric earthquakes. Five prehistoric earthquakes lie conspicuously near structures associated with the Commerce geophysical lineament, a NE-trending magnetic and gravity lineament lying oblique to the Wabash Valley Fault System and possibly extending over 600 km from NE Arkansas to central Indiana.

The Geysers-Clear Lake geothermal area, California - an updated geophysical perspective of heat sources

USGS Publications Warehouse

Stanley, W.D.; Blakely, R.J.

1995-01-01

The Geysers-Clear Lake geothermal area encompasses a large dry-steam production area in The Geysers field and a documented high-temperature, high-pressure, water-dominated system in the area largely south of Clear Lake, which has not been developed. An updated view is presented of the geological/geophysical complexities of the crust in this region in order to address key unanswered questions about the heat source and tectonics. Forward modeling, multidimensional inversions, and ideal body analysis of the gravity data, new electromagnetic sounding models, and arguments made from other geophysical data sets suggest that many of the geophysical anomalies have significant contributions from rock property and physical state variations in the upper 7 km and not from "magma' at greater depths. Regional tectonic and magmatic processes are analyzed to develop an updated scenario for pluton emplacement that differs substantially from earlier interpretations. In addition, a rationale is outlined for future exploration for geothermal resources in The Geysers-Clear Lake area. -from Authors

10 CFR 960.4-2-7 - Tectonics.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Tectonics. 960.4-2-7 Section 960.4-2-7 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Postclosure Guidelines § 960.4-2-7 Tectonics. (a) Qualifying condition. The site shall be located...

Problems of the active tectonics of the Eastern Black Sea

NASA Astrophysics Data System (ADS)

Javakhishvili, Z.; Godoladze, T.; Dreger, D. S.; Mikava, D.; Tvaliashvili, A.

2016-12-01

The Black Sea Basin is the part of the Arabian Eurasian Collision zone and important unit for understanding the tectonic process of the region. This complex basin comprises two deep basins, separated by the mid-Black Sea Ridge. The basement of the Black Sea includes areas with oceanic and continental crust. It was formed as a "back-arc" basin over the subduction zone during the closing of the Tethys Ocean. In the past decades the Black Sea has been the subject of intense geological and geophysical studies. Several papers were published about the geological history, tectonics, basement relief and crustal and upper mantle structure of the basin. New tectonic schemes were suggested (e. g. Nikishin et al 2014, Shillington et al. 2008, Starostenko et al. 2004 etc.). Nevertheless, seismicity of the Black Sea is poorly studied due to the lack of seismic network in the coastal area. It is considered, that the eastern basin currently lies in a compressional setting associated with the uplift of the Caucasus and structural development of the Caucasus was closely related to the evolution of the Eastern Black Sea Basin. Analyses of recent sequence of earthquakes in 2012 can provide useful information to understand complex tectonic structure of the Eastern Black Sea region. Right after the earthquake of 2012/12/23, National Seismic monitoring center of Georgia deployed additional 4 stations in the coastal area of the country, close to the epicenter area, to monitor aftershock sequence. Seismic activity in the epicentral area is continuing until now. We have relocated approximately 1200 aftershocks to delineate fault scarf using data from Georgian, Turkish and Russian datacenters. Waveforms of the major events and the aftershocks were inverted for the fault plane solutions of the events. For the inversion were used green's functions, computed using new 1D velocity model of the region. Strike-slip mechanism of the major events of the earthquake sequence indicates extensional features in the Eastern Black Sea Region as well.

Do tidal or swing waves roughen planetary surfaces?

NASA Astrophysics Data System (ADS)

Kochemasov, Gennady G.

2010-05-01

Surfaces of the terrestrial planets and their moons are far from being smooth. They are warped by several wavelengths and show a remarkable regularity: their roughness increases with the solar distance. Thus, if for Mercury the surface relief range does not exceed several km, for Mars it is already about 30 km. Earth's range is 20 km, Venus' one 14 km. Recently it was shown that this row of ranges reflects ratios of the tectonic granules radii of terrestrial planets [1, 2]. These radii related to unity of reduced planetary globes (in a geometrical model all planets are represented by even circles [2]) are as follows: Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2. It means that in the great planetary circles (equators) there are 32, 12, 8, and 4 tectonic granules (now they all are mapped by remote methods) and their numbers are inversely proportional to the orbital frequencies of the planets: higher frequency - smaller granule, and, vice versa, lower frequency - larger granule. In this planetary law is a firm confirmation of the main conceptual point of the wave planetology: "Orbits make structures" [3]. But how this happens? A basic reason lies in the keplerian elliptical orbits implying periodical changes of planetary bodies accelerations. Periodical slowing down and speeding up produce inertia-gravity waves warping any celestial body. In rotating bodies this wave warping is divided in four directions: two orthogonal and two diagonal. An interference of these directions produces tectonic blocks of three kinds: uplifting, subsiding, and neutral. Sizes and amplitudes of the blocks (granules) depend on the warping wavelengths and increase with the solar distance. Thus, a relief-forming potential and the actual relief range observed on the planets increase in this direction [1, 2, 4]. But the tidal forces diminish in this direction. That is why they cannot be a reason for the relief-forming potential. Having in mind a swinging action of planetary orbits on heavenly bodies one might think of swing forces and swing waves (contrary to the tidal waves) producing the wave warping surfaces and the deeper planetary spheres [1]. Three observations in relation with this revelation might be mentioned. 1. An increasing surface roughness of the icy satellites of Saturn with increasing distances from the planet [5]. 2. Atmospheric masses of terrestrial planets increase with the diminishing solar distance as a sequence of more frequent wave oscillations - a sweeping out making atmospheres volatiles from planetary depths is facilitated by more frequent oscillations. 3. The inner rapidly orbiting satellites of Jupiter (Io), Saturn (Enceladus), and Neptun (Triton) are still emitting volatiles as a result of more thorough sweeping out their volatile stock. Mercury also has traces of some metals in its exosphere (MESSENGER data). References: [1] Kochemasov G.G. (2009) A regular row of planetary relief ranges connected with tectonic granulations of celestial bodies // New Concepts in Global Tectonics Newsletter, # 51, 58-61. [2] Kochemasov G.G. (2009) A quantitative geometric model of relief-forming potential in terrestrial planets // EPSC Abstracts, Vol. 4, EPSC2009-16-1. [3] Kochemasov G.G. (1998) Tectonic dichotomy, sectoring and granulation of Earth and other celestial bodies // Proceedings of the International Symposium on New Concepts in Global Tectonics, "NCGT-98 TSUKUBA", Geological Survey of Japan, Tsukuba, Nov 20-23, 1998, 144-147. [4] Kochemasov G.G. (1993) Relief-forming potential of planets // 18th Russian-American microsymposium on planetology, Abstracts, Oct. 9-10, 1993, Moscow, Vernadsky Inst. (GEOKHI), 27-28. [5] Thomas, P.C., Veverka, J., Helfenstein, P., Porco, C. et al. (2006) Shapes of the saturnian icy satellites // Lunar and Planetary Science Conference XXXVII, Houston, USA, Abstract 1639 pdf. CD-ROM.

Imaging Crustal Structure with Waveform and HV Ratio of Body-wave Receiver Function

NASA Astrophysics Data System (ADS)

Chong, J.; Chu, R.; Ni, S.; Meng, Q.; Guo, A.

2017-12-01

It is known that receiver function has less constraint on the absolute velocity, and joint inversion of receiver function and surface wave dispersion has been widely applied to reduce the non-uniqueness of velocity and interface depth. However, some studies indicate that the receiver function itself is capable for determining the absolute shear wave velocity. In this study, we propose to measure the receiver function HV ratio which takes advantage of the amplitude information of the radial and vertical receiver functions to constrain the shear-wave velocity. Numerical analysis indicates that the receiver function HV ratio is sensitive to the average shear wave velocity in the depth range it samples, and can help to reduce the non-uniqueness of receiver function waveform inversion. A joint inversion scheme has been developed, and both synthetic tests and real data application proved the feasibility of the joint inversion. The method has been applied to the dense seismic array of ChinArray program in SE Tibet during the time period from August 2011 to August 2012 in SE Tibet (ChinArray-Himalaya, 2011). The measurements of receiver function HV ratio reveals the lateral variation of the tectonics in of the study region. And main features of the velocity structure imagined by the new joint inversion method are consistent with previous studies. KEYWORDS: receiver function HV ratio, receiver function waveform inversion, crustal structure ReferenceChinArray-Himalaya. 2011. China Seismic Array waveform data of Himalaya Project. Institute of Geophysics, China Earthquake Administration. doi:10.12001/ChinArray.Data. Himalaya. Jiajun Chong, Risheng Chu*, Sidao Ni, Qingjun Meng, Aizhi Guo, 2017. Receiver Function HV Ratio, a New Measurement for Reducing Non-uniqueness of Receiver Function Waveform Inversion. (under revision)

Thermochronological evidence for polyphase post-rift reactivation in SE Brazil

NASA Astrophysics Data System (ADS)

Cogné, N.; Gallagher, K.; Cobbold, P. R.; Riccomini, C.

2012-04-01

The continental margin of SE Brazil shows good evidence for tectonic activity well after the break-up of Western Gondwana (see Cobbold et al., 2001 for a review). Additionally, SE Brazil ranks as an HEPM (high elevation passive margin), summits reaching 2800 m. To constrain the onshore evolution of the margin, especially during the Tertiary, we did a new thermochronological and structural study. After an initial regional study, during which we found additional evidence for a major phase of exhumation during the Late Cretaceous to Early Tertiary (Cogné et al., 2011), we focussed on a region that was clearly subject to Tertiary tectonics. This region includes the Tertiary Taubaté basin and the adjacent Serra do Mar and Serra da Mantiqueira. We used two thermochronolgical methods on the same samples, apatite fission tracks (AFT) and U-Th/He on apatite (AHe). AFT ages range from 129.3±4.3 Ma to 60.7±1.9 Ma with mean track lengths (MTL) from 14.31±0.24 μm to 11.41±0.23 μm, whereas AHe ages range from 519.6±16.6 to 10.1±0.1 Ma. A subset of AHe ages, selected on the basis of data consistency and geological arguments, has a smaller range (122.4±2.5 to 45.1±1.5 Ma). We have combined inverse and forward modelling to assess the range of acceptable thermal histories. Results of inverse modelling confirm our earlier study by showing a Late Cretaceous phase of cooling. Around the onshore Taubaté Basin, for a limited number of samples, another period of cooling occurred during the Early Tertiary, around the time when the basin formed. The inferred thermal histories for most of the samples also imply a later reheating, followed by a Neogene cooling. According to forward modelling, the evidence for reheating seems to be robust around the margins of the Taubaté Basin, but elsewhere the data cannot really discriminate between this and a less complex thermal history. However forward modelling and geologically independent information support the conclusion that the whole area cooled and uplifted during the Neogene. The synchronicity of the cooling phases with tectonic pulses in the Andes and in NE Brazil, as well as the tectonic setting of the Tertiary basins (Cogné et al., submitted) lead us to attribute these phases to a plate-wide compressive stress, which reactivated inherited structures during the Late Cretaceous and Tertiary. The relief of the margin is therefore due, more to polyphase post-rift reactivation and uplift, than to rifting itself. - Cobbold, P.R., Meisling, K.E., Mount, V.S., 2001. Reactivation of an obliquely rifted margin, Campos and Santos Basins, Southeastern Brazil. AAPG Bulletin 85, 1925-1944. - Cogné, N., Gallagher, K., Cobbold, P.R., 2011. Post-rift reactivation of the onshore margin of southeast Brazil: Evidence from apatite (U-Th)/He and fission-track data. Earth and Planetary Science Letters 309, 118-130. - Cogné, N., Cobbold, P.R., Riccomini, C., Gallagher, K. Tectonic setting of the Taubaté basin (southeastern Brazil): insights from regional seismic profiles and outcrop data. Submitted to Journal of South American Earth Sciences.

Habitat characterization of the Vema Fracture Zone and Puerto Rico Trench

NASA Astrophysics Data System (ADS)

Devey, C. W.; Augustin, N.; Brandt, A.; Brenke, N.; Köhler, J.; Lins, L.; Schmidt, C.; Yeo, I. A.

2018-02-01

Although many of the regions on and close to the mid-ocean ridges have been extensively mapped and sampled, the abyssal intraplate regions remain essentially unsampled and unmapped, leaving huge gaps in our understanding of their geologic history and present activity. Prominent bathymetric features in these intraplate regions are fracture zones. Here we present bathymetric and sampling information from a transatlantic transect along the Vema Fracture Zone (ca. 11°N), covering crustal ages from 109 - 0 Ma on the African plate and 0-62 Ma on the South American plate. The Vema Fracture Zone is the intraplate trace of the active Vema Transform plate boundary, which offsets the present-day Mid-Atlantic Ridge by ca. 300 km left-laterally, juxtaposing zero-age crust with crust of 20 million years age. Our results show clear evidence of tectonic activity along most of the Fracture Zone, in most places likely associated with active fluid flow. Within the active Vema Transform at crustal ages of ca. 10 Ma we found clear indications of fluid flow both in the sediments and the overlying water column. This region is > 120 km from the nearest spreading axis and increases by almost an order of magnitude the maximum off-axis distance that active hydrothermal discharge has been found on the oceanic crust. Sampling of the igneous seafloor was possible at all crustal ages and the accretionary fabric imprinted on the plate during its production was prominent everywhere. Seafloor sediments show signs of extensive bioturbation. In one area, high concentrations of spherical Mn-nodules were also found and sampled. At the end of the transect we also mapped and sampled the Puerto Rico Trough, a > 8000 m-deep basin north of the Caribbean arc. Here the seafloor morphology is more complicated and strongly influenced by transpressive tectonics.

Geodynamic modelling of the rift-drift transition: Application to the Red Sea

NASA Astrophysics Data System (ADS)

Fierro, E.; Schettino, A.; Capitanio, F. A.; Ranalli, G.

2017-12-01

The onset of oceanic accretion after a rifting phase is generally accompanied by an initial fast pulse of spreading in the case of volcanic margins, such that the effective spreading rate exceeds the relative far-field velocity between the two plates for a short time interval. This pulse has been attributed to edge-driven convention (EDC), although our numerical modelling shows that the shear stress at the base of the lithosphere cannot exceed 1 MPa. In general, we have developed a 2D numerical model of the mantle instabilities during the rifting phase, in order to determine the geodynamic conditions at the rift-drift transition. The model was tested using Underworld II software, variable rheological parameters, and temperature and stress-dependent viscosity. Our results show an increase of strain rates at the top of the lithosphere with the lithosphere thickness as well as with the initial width of the margin up to 300 km. Beyond this value, the influence of the initial rift width can be neglected. An interesting outcome of the numerical model is the existence of an axial zone characterized by higher strain rates, which is flanked by two low-strain stripes. As a consequence, the model suggests the existence of an area of syn-rift compression within the rift valley. Regarding the post-rift phase, we propose that at the onset of a seafloor spreading, a phase of transient creep allows the release of the strain energy accumulated in the mantle lithosphere during the rifting phase, through anelastic relaxation. Then, the conjugated margins would be subject to post-rift contraction and eventually to tectonic inversion of the rift structures. To explore the tenability of this model, we introduce an anelastic component in the lithosphere rheology, assuming both the classical linear Kelvin-Voigt rheology and a non-linear Kelvin model. The non-linear model predicts viable relaxation times ( 1-2Myrs) to explain the post-rift tectonic inversion observed along the Arabian continental margin and the episodic initial fast seafloor spreading in the central Red Sea, where the role of EDC has been invoked.

Tectonic overpressure may reconcile the structural and petrological records of the Adula nappe (Central Alps)

NASA Astrophysics Data System (ADS)

Pleuger, Jan; Podladchikov, Yuri

2014-05-01

The Penninic Alps are the result of progressive underthrusting of oceanic and continental domains below the Adriatic microplate. Situated in the internal part of the Alpine orogen, they expose basement and thinned cover nappes which have been metamorphosed to variable degree, among them several units which were subjected to ultrahigh-pressure metamorphism. Due to the more or less strong nappe-internal deformation of these units, cross sections through the Penninic Alps cannot be restored kinematically by area or line balancing techniques. Instead, such restorations attempt to consistently reconcile geochronological and structural data and petrological pressure-temperature estimates. Pressure data are usually converted into depth assuming that they were lithostatic which puts the ultrahigh-pressure units to subcrustal depths. Tectonic exhumation of a unit from such a depth by whatever mechanism requires a large-scale normal fault with several tens of kilometres of displacement in the hanging wall of the unit. However, for all Penninic ultrahigh-pressure units (Dora Maira unit, Zermatt-Saas zone, Monviso unit, Adula-Cima Lunga nappe), the oldest mappable post-peak-pressure structures are related to top-to-the-foreland shearing, i.e. thrusting. There are two potential solutions to this dilemma. The first one is that either the exhumation was indeed accommodated by a large-scale normal fault which became completely overprinted during later deformational stages. The other one is that peak pressures were not lithostatic. To our knowledge, the first solution is applied to all kinematic models of the Alps so far. In order to explore the feasibility of the second solution, we performed a purely structural restoration of the NFP20-East cross section without lithostatic pressure-to-depth-conversions. This cross-section comprises the ultrahigh-pressure Adula nappe (up to ca. 30 kbar) and relies on quantitative strain data from the overlying units. The result shows that, in accordance with the structural record, the Adula nappe can be restored to maximum depths of up to ca. 60 km. For individual points of the Adula nappe in the restored cross section, corresponding to the sporadic occurences of (ultra)high-pressure rocks, lithostatic pressures are exceeded by petrological peak-pressure data by about 40% to 80%. Such amounts of tectonic overpressure are within the limits of theoretical considerations and numerical modelling results. For the other units comprised in the cross section, and for subsequent tectono-metamorphic stages of the Adula nappe, negligible amounts of overpressure (around 10%) are determined from the restoration. We conclude that (1) the NFP20-East cross section can be kinematically restored by using only structural data, (2) the dilemma mentioned above can be solved by admitting realisting amounts of tectonic overpressure, and (3) significant amounts of overpressure were established only locally and episodically.

Early Precambrian mantle derived rocks in the southern Prince Charles Mountains, East Antarctica: age and isotopic constraints

USGS Publications Warehouse

Mikhalsky, E.V.; Henjes-Kunst, F.; Roland, N.W.

2007-01-01

Mafic and ultramafic rocks occurring as lenses, boudins, and tectonic slabs within metamorphic units in the southern Mawson Escarpment display mantle characteristics of either a highly enriched, or highly depleted nature. Fractionation of these mantle rocks from their sources may be as old as Eoarchaean (ca 3850 Ma) while their tectonic emplacement probably occurred prior to 2550 Ma (U-Pb SHRIMP data). These results provide for the first time evidence for Archaean suturing within East Antarctica. Similar upper mantle sources are likely present in the northern Mawson Escarpment. A younger age limit of these rocks is 2200 Ma, as indicated by presumably metamorphic zircon ages while their magmatic age may be constrained by single zircon dates at 2450-2250 Ma. The area of the northern Mawson Escarpment is most likely of ensimatic origin and includes mafic rocks which were derived from distinct mantle source(s) during Palaeoproterozoic time.

Cenozoic structural inversion from transtension to transpression in Yingxiong Range, western Qaidam Basin: New insights into strike-slip superimposition controlled by Altyn Tagh and Eastern Kunlun Faults

NASA Astrophysics Data System (ADS)

Cheng, Xiang; Zhang, Daowei; Jolivet, Marc; Yu, Xiangjiang; Du, Wei; Liu, Runchao; Guo, Zhaojie

2018-01-01

A Cenozoic structural inversion event from transtension to transpression involving salt tectonics has been uncovered in the Yingxiong Range, the western Qaidam Basin. Seismic reflection data show that there are two common structural styles in the Yingxiong Range: (1) the positive flower structure; (2) the thrust-controlled fold at shallow depth and the positive inverted flower structure at deep levels, which are separated by a salt layer in the upper Xiaganchaigou Formation. The Yingxiong Range experienced a first stage of transtension in the Eocene, induced by the Altyn Tagh Fault, and a second stage of transpression from the early Miocene to present, jointly controlled by the Altyn Tagh and Eastern Kunlun Faults. The Eocene transtension produced numerous NW-striking right-stepping en-échelon transtensional normal faults or fractures in the Yingxiong Range. At the same time, evaporites and mudstone were deposited in the vicinity of these faults. In the early Miocene, the Eocene transtensional normal faults were reactivated in a reverse sense, and the thrust-controlled folds at shallow depth started to form simultaneously. With transpression enhanced in the late Cenozoic, positive flower structures directly formed in places without evaporites. The Cenozoic transtension to transpression inversion of the Yingxiong Range is the result of strike-slip superimposition controlled by the Altyn Tagh and Eastern Kunlun Faults in time and space.

A fault‐based model for crustal deformation in the western United States based on a combined inversion of GPS and geologic inputs

USGS Publications Warehouse

Zeng, Yuehua; Shen, Zheng-Kang

2017-01-01

We develop a crustal deformation model to determine fault‐slip rates for the western United States (WUS) using the Zeng and Shen (2014) method that is based on a combined inversion of Global Positioning System (GPS) velocities and geological slip‐rate constraints. The model consists of six blocks with boundaries aligned along major faults in California and the Cascadia subduction zone, which are represented as buried dislocations in the Earth. Faults distributed within blocks have their geometrical structure and locking depths specified by the Uniform California Earthquake Rupture Forecast, version 3 (UCERF3) and the 2008 U.S. Geological Survey National Seismic Hazard Map Project model. Faults slip beneath a predefined locking depth, except for a few segments where shallow creep is allowed. The slip rates are estimated using a least‐squares inversion. The model resolution analysis shows that the resulting model is influenced heavily by geologic input, which fits the UCERF3 geologic bounds on California B faults and ±one‐half of the geologic slip rates for most other WUS faults. The modeled slip rates for the WUS faults are consistent with the observed GPS velocity field. Our fit to these velocities is measured in terms of a normalized chi‐square, which is 6.5. This updated model fits the data better than most other geodetic‐based inversion models. Major discrepancies between well‐resolved GPS inversion rates and geologic‐consensus rates occur along some of the northern California A faults, the Mojave to San Bernardino segments of the San Andreas fault, the western Garlock fault, the southern segment of the Wasatch fault, and other faults. Off‐fault strain‐rate distributions are consistent with regional tectonics, with a total off‐fault moment rate of 7.2×1018">7.2×1018 and 8.5×1018  N·m/year">8.5×1018  N⋅m/year for California and the WUS outside California, respectively.

PIK3CA-associated developmental disorders exhibit distinct classes of mutations with variable expression and tissue distribution

PubMed Central

Timms, Andrew E.; Conti, Valerio; Girisha, Katta M.; Martin, Beth; Olds, Carissa; Collins, Sarah; Park, Kaylee; Carter, Melissa; Krägeloh-Mann, Inge; Chitayat, David; Parikh, Aditi Shah; Bradshaw, Rachael; Torti, Erin; Braddock, Stephen; Burke, Leah; Ghedia, Sondhya; Stephan, Mark; Stewart, Fiona; Prasad, Chitra; Napier, Melanie; Saitta, Sulagna; Straussberg, Rachel; Gabbett, Michael; O’Connor, Bridget C.; Yin, Lim Jiin; Lai, Angeline Hwei Meeng; Martin, Nicole; McKinnon, Margaret; Addor, Marie-Claude; Schwartz, Charles E.; Lanoel, Agustina; Conway, Robert L.; Devriendt, Koenraad; Tatton-Brown, Katrina; Pierpont, Mary Ella; Painter, Michael; Worgan, Lisa; Reggin, James; Hennekam, Raoul; Pritchard, Colin C.; Aracena, Mariana; Gripp, Karen W.; Cordisco, Maria; Van Esch, Hilde; Garavelli, Livia; Curry, Cynthia; Goriely, Anne; Kayserilli, Hulya; Shendure, Jay; Graham, John; Guerrini, Renzo; Dobyns, William B.

2016-01-01

Mosaicism is increasingly recognized as a cause of developmental disorders with the advent of next-generation sequencing (NGS). Mosaic mutations of PIK3CA have been associated with the widest spectrum of phenotypes associated with overgrowth and vascular malformations. We performed targeted NGS using 2 independent deep-coverage methods that utilize molecular inversion probes and amplicon sequencing in a cohort of 241 samples from 181 individuals with brain and/or body overgrowth. We identified PIK3CA mutations in 60 individuals. Several other individuals (n = 12) were identified separately to have mutations in PIK3CA by clinical targeted-panel testing (n = 6), whole-exome sequencing (n = 5), or Sanger sequencing (n = 1). Based on the clinical and molecular features, this cohort segregated into three distinct groups: (a) severe focal overgrowth due to low-level but highly activating (hotspot) mutations, (b) predominantly brain overgrowth and less severe somatic overgrowth due to less-activating mutations, and (c) intermediate phenotypes (capillary malformations with overgrowth) with intermediately activating mutations. Sixteen of 29 PIK3CA mutations were novel. We also identified constitutional PIK3CA mutations in 10 patients. Our molecular data, combined with review of the literature, show that PIK3CA-related overgrowth disorders comprise a discontinuous spectrum of disorders that correlate with the severity and distribution of mutations. PMID:27631024

The basement of the Punta del Este Terrane (Uruguay): an African Mesoproterozoic fragment at the eastern border of the South American Río de La Plata craton

NASA Astrophysics Data System (ADS)

Basei, Miguel A. S.; Peel, Elena; Sánchez Bettucci, Leda; Preciozzi, Fernando; Nutman, Allen P.

2011-04-01

The Punta del Este Terrane (eastern Uruguay) lies in a complex Neoproterozoic (Brasiliano/Pan-African) orogenic zone considered to contain a suture between South American terranes to the west of Major Gercino-Sierra Ballena Suture Zone and eastern African affinities terranes. Zircon cores from Punta del Este Terrane basement orthogneisses have U-Pb ages of ca. 1,000 Ma, which indicate an lineage with the Namaqua Belt in Southwestern Africa. U-Pb zircon ages also provide the following information on the Punta del Este terrane: the orthogneisses containing the ca. 1,000 Ma inheritance formed at ca. 750 Ma; in contrast to the related terranes now in Africa, reworking of the Punta del Este Terrane during Brasiliano/Pan-African orogenesis was very intense, reaching granulite facies at ca. 640 Ma. The termination of the Brasiliano/Pan-African orogeny is marked by formation of acid volcanic and volcanoclastic rocks at ca. 570 Ma (Sierra de Aguirre Formation), formation of late sedimentary basins (San Carlos Formation) and then intrusion at ca. 535 Ma of post-tectonic granitoids (Santa Teresa and José Ignacio batholiths). The Punta del Este Terrane and unrelated western terranes represented by the Dom Feliciano Belt and the Río de La Plata Craton were in their present positions by ca. 535 Ma.

Crustal strength anisotropy influences landscape form and longevity

NASA Astrophysics Data System (ADS)

Roy, S. G.; Koons, P. O.; Upton, P.; Tucker, G. E.

2013-12-01

Lithospheric deformation is increasingly recognized as integral to landscape evolution. Here we employ a coupled orogenic and landscape model to test the hypothesis that strain-induced crustal failure exerts the dominant control on rates and patterns of orogenic landscape evolution. We assume that erodibility is inversely proportional to cohesion for bedrock rivers host to bedload abrasion. Crustal failure can potentially reduce cohesion by several orders of magnitude along meter scale planar fault zones. The strain-induced cohesion field is generated by use of a strain softening upper crustal rheology in our orogenic model. Based on the results of our coupled model, we predict that topographic anisotropy found in natural orogens is largely a consequence of strain-induced anisotropy in the near surface strength field. The lifespan and geometry of mountain ranges are strongly sensitive to 1) the acute division in erodibility values between the damaged fault zones and the surrounding intact rock and 2) the fault zone orientations for a given tectonic regime. The large division in erodibility between damaged and intact rock combined with the dependence on fault zone orientation provides a spectrum of rates at which a landscape will respond to tectonic or climatic perturbations. Knickpoint migration is about an order of magnitude faster along the exposed cores of fault zones when compared to rates in intact rock, and migration rate increases with fault dip. The contrast in relative erosion rate confines much of the early stage fluvial erosion and establishes a major drainage network that reflects the orientations of exposed fault zones. Slower erosion into the surrounding intact rock typically creates small tributaries that link orthogonally to the structurally confined channels. The large divide in fluvial erosion rate permits the long term persistence of the tectonic signal in the landscape and partly contributes to orogen longevity. Landscape morphology and channel tortuosity together provide critical information on the orientation and spatial distribution of fault damage and the relevant tectonic regime. Our landscape evolution models express similar mechanisms and produce drainage network patterns analogous to those seen in the Southern Alps of New Zealand and the Himalayan Eastern Syntaxis, both centers of active lithospheric deformation.

The influence of tectonic inheritance on crustal extension style following failed subduction of continental crust: applications to metamorphic core complexes in Papua New Guinea

NASA Astrophysics Data System (ADS)

Biemiller, J.; Ellis, S. M.; Little, T.; Mizera, M.; Wallace, L. M.; Lavier, L.

2017-12-01

The structural, mechanical and geometric evolution of rifted continental crust depends on the lithospheric conditions in the region prior to the onset of extension. In areas where tectonic activity preceded rift initiation, structural and physical properties of the previous tectonic regime may be inherited by the rift and influence its development. Many continental rifts form and exhume metamorphic core complexes (MCCs), coherent exposures of deep crustal rocks which typically surface as arched or domed structures. MCCs are exhumed in regions where the faulted upper crust is displaced laterally from upwelling ductile material along a weak detachment fault. Some MCCs form during extensional inversion of a subduction thrust following failed subduction of continental crust, but the degree to which lithospheric conditions inherited from the preceding subduction phase control the extensional style in these systems remains unclear. For example, the Dayman Dome in Southeastern Papua New Guinea exposes prehnite-pumpellyite to greenschist facies rocks in a smooth 3 km-high dome exhumed with at least 24 km of slip along one main detachment normal fault, the Mai'iu Fault, which dips 21° at the surface. The extension driving this exhumation is associated with the cessation of northward subduction of Australian continental crust beneath the oceanic lithosphere of the Woodlark Plate. We use geodynamic models to explore the effect of pre-existing crustal structures inherited from the preceding subduction phase on the style of rifting. We show that different geometries and strengths of inherited subduction shear zones predict three distinct modes of subsequent rift development: 1) symmetric rifting by newly formed high-angle normal faults; 2) asymmetric rifting along a weak low-angle detachment fault extending from the surface to the brittle-ductile transition; and 3) extension along a rolling-hinge structure which exhumes deep crustal rocks in coherent rounded exposures. We propose the latter mode as an exhumation model for Dayman Dome and compare the model predictions to regional geophysical and geological evidence. Our models find that tectonically inherited subduction structures may strongly control subsequent extension style when the subduction thrust is weak and well-oriented for reactivation.

Linking the tectonic evolution with fluid history in magma-poor rifted margins: tracking mantle- and continental crust-related fluids

NASA Astrophysics Data System (ADS)

Pinto, V. H. G.; Manatschal, G.; Karpoff, A. M.

2014-12-01

The thinning of the crust and the exhumation of subcontinental mantle is accompanied by a series of extensional detachment faults. Exhumation of mantle and crustal rocks is intimately related to percolation of fluids along detachment faults leading to changes in mineralogy and chemistry of the mantle, crustal and sedimentary rocks. Field observation, analytical methods, refraction/reflection and well-core data, allowed us to investigate the role of fluids in the Iberian margin and former Alpine Tethys distal margins and the Pyrenees rifted system. In the continental crust, fluid-rock interaction leads to saussuritization that produces Si and Ca enriched fluids found in forms of veins along the fault zone. In the zone of exhumed mantle, large amounts of water are absorbed in the first 5-6 km of serpentinized mantle, which has the counter-effect of depleting the mantle of elements (e.g., Si, Ca, Mg, Fe, Mn, Ni and Cr) forming mantle-related fluids. Using Cr-Ni-V and Fe-Mn as tracers, we show that in the distal margin, mantle-related fluids used detachment faults as pathways and interacted with the overlying crust, the sedimentary basin and the seawater, while further inward parts of the margin, continental crust-related fluids enriched in Si and Ca impregnated the fault zone and may have affected the sedimentary basin. The overall observations and results enable us to show when, where and how these interactions occurred during the formation of the rifted margin. In a first stage, continental crust-related fluids dominated the rifted systems. During the second stage, mantle-related fluids affected the overlying syn-tectonic sediments through direct migration along detachment faults at the future distal margin. In a third stage, these fluids reached the seafloor, "polluted" the seawater and were absorbed by post-tectonic sediments. We conclude that a significant amount of serpentinization occurred underneath the thinned continental crust, that the mantle-related fluids might have modified the chemical composition of the sediments and seawater. We propose that the chemical signature of serpentinization that occurs during the mantle exhumation is recorded in the sediments and may serve as a proxy to date serpentinization and mantle exhumation in present day magma-poor rifted margins.

On the Yield Strength of Oceanic Lithosphere

NASA Astrophysics Data System (ADS)

Jain, Chhavi; Korenaga, Jun; Karato, Shun-ichiro

2017-10-01

The yield strength of oceanic lithosphere determines the mode of mantle convection in a terrestrial planet, and low-temperature plasticity in olivine aggregates is generally believed to govern the plastic rheology of the stiffest part of lithosphere. Because, so far, proposed flow laws for this mechanism exhibit nontrivial discrepancies, we revisit the recent high-pressure deformation data of Mei et al. (2010) with a comprehensive inversion approach based on Markov chain Monte Carlo sampling. Our inversion results indicate that the uncertainty of the relevant flow law parameters is considerably greater than previously thought. Depending on the choice of flow law parameters, the strength of oceanic lithosphere would vary substantially, carrying different implications for the origin of plate tectonics on Earth. To reduce the flow law ambiguity, we suggest that it is important to establish a theoretical basis for estimating macroscopic stress in high-pressure experiments and also to better utilize marine geophysical observations.

Ovarian cancer risk, ALDH2 polymorphism and alcohol drinking: Asian data from the Ovarian Cancer Association Consortium.

PubMed

Ugai, Tomotaka; Kelemen, Linda E; Mizuno, Mika; Ong, Jue-Sheng; Webb, Penelope M; Chenevix-Trench, Georgia; Wicklund, Kristine G; Doherty, Jennifer Anne; Rossing, Mary Anne; Thompson, Pamela J; Wilkens, Lynne R; Carney, Michael E; Goodman, Marc T; Schildkraut, Joellen M; Berchuck, Andrew; Cramer, Daniel W; Terry, Kathryn L; Cai, Hui; Shu, Xiao-Ou; Gao, Yu-Tang; Xiang, Yong-Bing; Van Den Berg, David; Pike, Malcom C; Wu, Anna H; Pearce, Celeste Leigh; Matsuo, Keitaro

2018-02-01

The aldehyde dehydrogenase 2 (ALDH2) polymorphism rs671 (Glu504Lys) causes ALDH2 inactivation and adverse acetaldehyde exposure among Asians, but little is known of the association between alcohol consumption and rs671 and ovarian cancer (OvCa) in Asians. We conducted a pooled analysis of Asian ancestry participants in the Ovarian Cancer Association Consortium. We included seven case-control studies and one cohort study comprising 460 invasive OvCa cases, 37 borderline mucinous OvCa and 1274 controls of Asian descent with information on recent alcohol consumption. Pooled odds ratios (OR) with 95% confidence intervals (CI) for OvCa risk associated with alcohol consumption, rs671 and their interaction were estimated using logistic regression models adjusted for potential confounders. No significant association was observed for daily alcohol intake with invasive OvCa (OR comparing any consumption to none = 0.83; 95% CI = 0.58-1.18) or with individual histotypes. A significant decreased risk was seen for carriers of one or both Lys alleles of rs671 for invasive mucinous OvCa (OR = 0.44; 95% CI = 0.20-0.97) and for invasive and borderline mucinous tumors combined (OR = 0.48; 95% CI = 0.26-0.89). No significant interaction was observed between alcohol consumption and rs671 genotypes. In conclusion, self-reported alcohol consumption at the quantities estimated was not associated with OvCa risk among Asians. Because the rs671 Lys allele causes ALDH2 inactivation leading to increased acetaldehyde exposure, the observed inverse genetic association with mucinous ovarian cancer is inferred to mean that alcohol intake may be a risk factor for this histotype. This association will require replication in a larger sample. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Electrical Conductivity Model of the Mantle Lithosphere of the Slave Craton (NW Canada) and its tectonic interpretation in the context of Geochemical Results

NASA Astrophysics Data System (ADS)

Lezaeta, P.; Chave, A.; Evans, R.; Jones, A. G.; Ferguson, I.

2002-12-01

The Slave Craton, northwestern Canada, contains the oldest known rocks on Earth, with exposed outcrop over an area of about 600x400 km2. The discovery of economic diamondiferous kimberlite pipes during the early 1990s motivated extensive research in the region. Over the last six years, four types of deep-probing magnetotelluric (MT) surveys were conducted within the framework of diverse geoscientific programs, aimed at determining the regional-scale electrical structures of the craton. Two of the surveys involved novel acquisition; one through frozen lake ice along ice roads during winter, and the second deploying ocean-bottom instrumentation from float planes during summer. The latter surveys required one year of recording between summers, thus allowing long period transfer functions that lead to mantle penetration depths of over 300 km. Two-dimensional modeling of the MT data from along the winter road showed the existence of a high conductivity zone at depths of 80-120 km beneath the central Slave craton. This anomalous region is spatially coincident with an ultradepleted harzburgitic layer in the upper mantle that was interpreted by others to be related to a subducted slab emplaced during the mid-Archean. A 3-D electrical conductivity model of the Slave lithosphere has been obtained, by trial and error, to fit the magnetic transfer and MT response functions from the lake experiments. This 3-D model traces the central Slave conductor as a NE-SW oriented mantle structure. Its NE-SW orientation coincides with that of a late fold belt system, with the first phase of craton-wide plutonism at ca 2630-2590 Ma, three-part subdivision of the craton based on SKS results, and with a G10 (garnet) geochemical mantle boundaries. All of these highlight a NE-SW structural grain to the lithospheric mantle of the craton, in sharp contrast to the N-S grain of the crust. Constraints on the depth range and lateral extension of the electrical conductive structure are obtained through a sensitivity analysis to verify a recent hypothesis about tectonic imbrication of lithosphere emplaced at ca 2.6 Ga in which SE-NW subduction is proposed. If such subduction has taken place, and arc-related or oceanic lithosphere has been trapped in the system, then an enhanced conductivity in the mantle deepening to NW supports the tectonic model.

Use of Digital Elevation Models to understand map landforms and history of the magmatism Khibiny Massif (Kola Peninsula, Russia)

NASA Astrophysics Data System (ADS)

Chesalova, Elena; Asavin, Alex

2016-04-01

This work presents an improved geomorphological methodology that uses 3D model of relief, remotely-sensed data, geological, geophysical maps and tools of Geographical Information Systems. On the basis of maps of 1: 50,000 and 1: 200,000 the Digital Elevation model (DEM) of Khibiny massif was developed. We used software ARC / INFO v10.2 ESRI. A DEM was used for analyzing landform by extracting the slope gradient, curvature, valley pro?les, slope, aspect and so on. The results were gradually re?ned from the interpretation of satellite imagery and geological map Geomorphological analysis will allow us to determine spatial regularities in inner massive construction. We try to found areas where gas emissions (CH4/H2) enrich, according to morphometry, geology, tectonic and other environments. The main regional blocks were de?ned by different morphological evidences: impression zone, similar to subsidence caldera; uplift zone, domed area (located in the highest part of massif and zone of intersection of main faults) and others. It says that there are the few stages in the development of the Khibiny massif. There is no common concept of the consequence of intrudes magmatic phases now. And we hope that our geomorphical analysis take a new evidences about this problems. Locations of the blocks' borders (tectonic zones) were recognized by lineament analysis of valleys and tectonic faults presented in relief. Erosion system is represented by valleys of 4 ranks. It inherits the zone of tectonic disturbances 3 groups of faults were recognized: 1) Global lineament system cross whole peninsula - existing before Khibiny massif intrusion; 2) Faults associated with the formation of the intrusive phases sequence and magma differentiation and with later collision history during magma cooling; 3) Crack system related to neotectonic process. We believed that if different magmatic phases intrude in similar tectonic environment, the common spatial system of faults will be formed. Really we observed a confederated system of contraction faults for different phases suggests that the differentiation within the intrusion is implemented as a single magma chamber for different intrusive phases. It remains an open question - which fault system (old or young) is more productive to gas emissions? The discrepancy of the geological structures and land forms is established. • Impression zone is represented by foyaites (high-strength rocks) • Uplift zone - rischorrites, khibinites (low-strength rocks) • Trough valley - weakened zone of tectonic faults - yuvites, urtites, rischorrites (low-strength rocks) • In the lowest part of depression zone - carbonatite stock It looks like an inversion of lithomorphic properties and the rock's morphological expression - it is a subject to uplift tectonics. Positive forms of relief (domed area and swells) could be formed due to the intrusion of secondary highly differentiated melts of low density. Also our early studies con?rm that rischorrites is one of the more rich ?uid gases rocks in Khibina massive. And we expect the strong emission of gas in the areas of distribution of these rock. Low density and increase buoyancy of magma, as a result of high gas concentration, can increase difference between density of cumulus minerals and intercumulus melts. This inversion between melt density and cumulus density, which are formed during chamber melt differentiation, and their low viscosity can cause formation of the local swells. Swells are located in the areas of crossing tectonic faults. This can lead to vertical movements, caused by elevating power of micro diapirs. Such diapirs forms are observed on the block diagrams of apatite ores in Koashve (Ivanyuk et. al., 2012). We observe such structure in middle zone of Khibiny massif, near Kuelporr deposit, about 15 km long and 5 km width and one with less size near Rasvumchorr deposit, about 10x3 km. This is the area of rischorrite's appearance. And in this area we see locations of the most intense free gas emission. The technical possibilities that are offered by Remote Sensing (RS) and Geographical Information Systems (GIS) facilitate the geomorphological investigation of inhospitable and inaccessible mountain areas Digital Elevation Models (DEMs) are valuable tools for approximation of the real world's continuous surface. They allow a visual analysis of the earth's surface morphology, quanti?cation of sediment volumes and the calculation of topographic derivatives such as the slope gradient, slope aspect and pro?le curvature that consume ?eld investigations and optimize time The project has been sponsored by programmm Presidium of RAS P44. Reference Ivanyuk G, Kalashnikov A, Mikhailova J, Konoplyova N, Goryainov P, Yakovenchuk V, Pakhomovsky Y. Self-Organization of the Khibiny Alkaline Massif (Kola Peninsula, Russia). In Earth Sciences, Dr. Imran Ahmad Dar(Ed.), ISBN: 978-953-307-861-8, InTech, Available from: http://www.intechopen.com/books/earth-sciences/self-organization-of-the-khibiny-alkaline -massif -kolapeninsula-russia INTECH Open Access Publisher; 2012, Head7, P.131-156.

Constraints on the history and topography of the Northeastern Sierra Nevada from a Neogene sedimentary basin in the Reno-Verdi area, Western Nevada

USGS Publications Warehouse

Trexler, James; Cashman, Patricia; Cosca, Michael

2012-01-01

Neogene (Miocene–Pliocene) sedimentary rocks of the northeastern Sierra Nevada were deposited in small basins that formed in response to volcanic and tectonic activity along the eastern margin of the Sierra. These strata record an early phase (ca. 11–10 Ma) of extension and rapid sedimentation of boulder conglomerates and debrites deposited on alluvial fans, followed by fluvio-lacustrine sedimentation and nearby volcanic arc activity but tectonic quiescence, until ~ 2.6 Ma. The fossil record in these rocks documents a warmer, wetter climate featuring large mammals and lacking the Sierran orographic rain shadow that dominates climate today on the eastern edge of the Sierra. This record of a general lack of paleo-relief across the eastern margin of the Sierra Nevada is consistent with evidence presented elsewhere that there was not a significant topographic barrier between the Pacific Ocean and the interior of the continent east of the Sierra before ~ 2.6 Ma. However, these sediments do not record an integrated drainage system either to the east into the Great Basin like the modern Truckee River, or to the west across the Sierra like the ancestral Feather and Yuba rivers. The Neogene Reno-Verdi basin was one of several, scattered endorheic (i.e., internally drained) basins occupying this part of the Cascade intra-arc and back-arc area.

A non-zircon Hf isotope record in Archean black shales from the Pilbara craton confirms changing crustal dynamics ca. 3 Ga ago.

PubMed

Nebel-Jacobsen, Yona; Nebel, Oliver; Wille, Martin; Cawood, Peter A

2018-01-17

Plate tectonics and associated subduction are unique to the Earth. Studies of Archean rocks show significant changes in composition and structural style around 3.0 to 2.5 Ga that are related to changing tectonic regime, possibly associated with the onset of subduction. Whole rock Hf isotope systematics of black shales from the Australian Pilbara craton, selected to exclude detrital zircon components, are employed to evaluate the evolution of the Archean crust. This approach avoids limitations of Hf-in-zircon analyses, which only provide input from rocks of sufficient Zr-concentration, and therefore usually represent domains that already underwent a degree of differentiation. In this study, we demonstrate the applicability of this method through analysis of shales that range in age from 3.5 to 2.8 Ga, and serve as representatives of their crustal sources through time. Their Hf isotopic compositions show a trend from strongly positive εHf initial values for the oldest samples, to strongly negative values for the younger samples, indicating a shift from juvenile to differentiated material. These results confirm a significant change in the character of the source region of the black shales by 3 Ga, consistent with models invoking a change in global dynamics from crustal growth towards crustal reworking around this time.

Moment tensor inversion of tremor events at Arenal Volcano (Costa Rica)

NASA Astrophysics Data System (ADS)

Davi, Rosalia; O'Brien, Gareth; Lokmer, Ivan; Bean, Christopher; Lesage, Philippe; de Barros, Louis

2010-05-01

Arenal is a small, andesitic stratovolcano located in north-western Costa Rica, 97 km from the capital San Josè. Arenal's explosive activity is preceded, and accompanied, by different types of seismic events such as long period events, explosions, tremor and sporadic tectonic swarms. Tremor is the most common type of event recorded at Arenal with durations of up to several hours. Both spasmodic (1-6 Hz) and harmonic (0.9-2 Hz) tremor are observed with no clear difference in the genesis of each; the former can progressively evolve into the latter and vice-versa. However, the origin of the tremor is, at present, not fully understood. In order to retrieve the source mechanism generating these types of events, a moment tensor inversion is performed. A dataset recorded on the volcano, during a seismic experiment carried out in 2005, is used for the inversion. This dataset consists of ten days of data, from which two main groups of tremor at different frequencies (group one at 0.8-1.5 Hz and group two at 1.8-2.5 Hz) have been selected. A major difficulty in any inversion of tremor is that a clear onset can rarely be determined and hence retrieving the direct arrivals from the source is impossible. Usually, these arrivals are heavily contaminated by scattered waves. On Arenal the initial part of the tremor bands can be isolated, therefore offering a good opportunity to invert tremor for the source mechanism. The Green's functions used in the inversion were calculated using 3D numerical simulations including the real topography of the volcano and the best estimation of the velocity model available for Arenal. This velocity model was retrieved from seismic refraction experiments and sounding using the SPAC method. For each day, different tremor starting bands have been selected and divided into the groups mentioned above. For each band a source location is determined by performing a grid search through a volume of 4735 possible source points located under the crater summit. From the evaluation of the misfit values, a common source location is determined. The source appears to be located in shallow position, (less than 200 meters deep) under the crater summit. The source mechanisms for each tremor bands are retrieved for each day using the inversion procedure.