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Sample records for active continental collision

  1. Continental collisions and seismic signature

    NASA Astrophysics Data System (ADS)

    Meissner, R.; Wever, Th.; Sadowiak, P.

    1991-04-01

    Reflection seismics in compressional belts has revealed the structure of crustal shortening and thickening processes, showing complex patterns of indentation and interfingering of colliding crusts and subcrustal lithospheres. Generally, in the upper crust large zones of detachments develop, often showing duplexes and 'crocodile' structures. The lower crust from zones of active collision (e.g. Alps, Pyrenees) is characterized by strongly dipping reflections. The base of the crust with the Moho must be continuously equilibrating after orogenic collapse as areas of former continental collision exhibit flat Mohos and subhorizontal reflections. The depth to the Moho increases during collision and decreases after the onset of post-orogenic extension, until finally the crustal root disappears completely together with the erosion of the mountains. Processes, active during continental collisions and orogenic collapse, create distinct structures which are imaged by reflection seismic profiling. Examples are shown and discussed.

  2. Basins in ARC-continental collisions

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.

    2012-01-01

    Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

  3. Combined Active and Passive Seismology to Study Continental Collision; Central South Island of New Zealand

    NASA Astrophysics Data System (ADS)

    Stern, T.; Okaya, D.; Baldock, G.; Scherwath, M.

    2005-12-01

    Central South Island of New Zealand is a continental region that has undergone both collision and strike-slip shear in the late Tertiary. From a tectonics, or rock-mechanics, view-point there is an interest in how the crust and mantle have been both thickened and sheared. The South Island Geophysical Transect (SIGHT) and the Southern Alps Passive Seismic Experiment (SAPSE) - both jointly funded US-NZ programs - studied these processes. Some of the most important findings came about by merging data from passive and active seismology. Three specific examples will be discussed: 1. Teleseismic P-wave delays from earthquakes in the Western Pacific are used to map a ~ 0.8-1 s speed-up in the mantle right beneath the region of thickest crust and highest topography of the collision zone. Forward modeling of this velocity anomaly shows that the amplitude of the anomaly can be explained by a 100 km-thick body that has a 7% in increase in P-wave speed. From the spatial pattern of the P-wave residuals we can also show that the high-speed body is about 80-100 km wide and roughly vertically disposed beneath the crustal root. The shape and position of the high-speed body beneath the seismically determined crustal root is consistent with it being thickened, and therefore cold, mantle lithosphere that has uniformly strained into a roughly symmetric root beneath the collision zone. 2. Pn anisotropy measurements from our onshore-offshore seismic shooting program allowed us to make mutually perpendicular determinations of Pn wave speeds at three localities. P-wave anisotropies of up to 11 ± 3%, 6.5 ± 2.5% and 0 ± 3%, were measured, depending on the distance of the measurement from the surface trace of the plate boundary (the Alpine Fault). These are necessarily minimum anisotropy values because it assumes that the two axes of measurement are those of minimum and maximum wave speed. Combining these results with SKS splitting values of ~ 2 s from passive seismology allowed us to make

  4. Collision zone magmatism aids continental crustal growth

    NASA Astrophysics Data System (ADS)

    Savov, Ivan; Meliksetian, Khachatur; Ralf, Halama; Gevorg, Navasardian; Chuck, Connor; Massimo, D'Antonio; Samuele, Agostini; Osamu, Ishizuka; Sergei, Karapetian; Arkadi, Karakhanian

    2014-05-01

    The continental crust has a broadly andesitic bulk composition and is predominantly generated at convergent margins. However, estimates of the bulk composition of oceanic arcs indicate a bulk composition closer to basalt than to andesite. Hence, reworking processes that transform basaltic island arc crust into andesitic continental crust are essential[1] and explaining growth of andesitic continental crust via accretion of arc crustal fragments remains problematic. Recent studies of magmatism in the Great Tibetan Plateau[2], as site of multiple and still active continent-continent collisions, have proposed that andesitic CC is generated via amalgamation of large volumes of collision-related felsic magmas generated by melting of hydrated oceanic crust with mantle geochemical signatures. We aim to test this hypothesis by evaluating geochemical data from the volcanically and tectonically active Lesser Caucasus region (Armenia, Azerbaijan, Georgia and E. Turkey), as the only other region where active continent-continent collision takes place. We will benefit from the newly compiled volcano-tectonic database of collision-related volcanic and plutonic rocks of Armenia that is comparable in quality and detail to the one available on Tibet. Our dataset combines several detailed studies from the large Aragats shield volcano[3] and associated monogenetic volcanic fields (near the capital city of Yerevan), as well as > 500 Quaternary to Holocene volcanoes from Gegham, Vardenis and Syunik volcanic highlands (toward Armenia-Nagorno-Karabakh-Azerbaijan-Iran border). The Armenian collision-related magmatism is diverse in volume, composition, eruption style and volatile contents. Interestingly, the majority of exposed volcanics are andesitic in composition. Nearly all collision-related volcanic rocks, even the highly differentiated dacite and rhyolite ignimbrites, have elevated Sr concentrations and 87Sr/86Sr and 143Nd/144Nd ratios varying only little (average ~ 0.7043 and ~ 0

  5. A numerical investigation of continental collision styles

    NASA Astrophysics Data System (ADS)

    Ghazian, Reza Khabbaz; Buiter, Susanne J. H.

    2013-06-01

    Continental collision after closure of an ocean can lead to different deformation styles: subduction of continental crust and lithosphere, lithospheric thickening, folding of the unsubducted continents, Rayleigh-Taylor (RT) instabilities and/or slab break-off. We use 2-D thermomechanical models of oceanic subduction followed by continental collision to investigate the sensitivity of these collision styles to driving velocity, crustal and lithospheric temperature, continental rheology and the initial density difference between the oceanic lithosphere and the asthenosphere. We find that these parameters influence the collision system, but that driving velocity, rheology and lithospheric (rather than Moho and mantle) temperature can be classified as important controls, whereas reasonable variations in the initial density contrast between oceanic lithosphere and asthenosphere are not necessarily important. Stable continental subduction occurs over a relatively large range of values of driving velocity and lithospheric temperature. Fast and cold systems are more likely to show folding, whereas slow and warm systems can experience RT-type dripping. Our results show that a continent with a strong upper crust can experience subduction of the entire crust and is more likely to fold. Accretion of the upper crust at the trench is feasible when the upper crust has a moderate to weak strength, whereas the entire crust can be scraped-off in the case of a weak lower crust. We also illustrate that weakening of the lithospheric mantle promotes RT-type of dripping in a collision system. We use a dynamic collision model, in which collision is driven by slab pull only, to illustrate that adjacent plates can play an important role in continental collision systems. In dynamic collision models, exhumation of subducted continental material and sediments is triggered by slab retreat and opening of a subduction channel, which allows upward flow of buoyant materials. Exhumation continues

  6. Active Dehydration, Delamination and Deformation of Transitional Continental Crust in an Arc-Continent Collision, Taiwan

    NASA Astrophysics Data System (ADS)

    Byrne, T. B.; Rau, R. J.; Chen, K. H.; Huang, H. H.; Wang, Y. J.; Ouimet, W. B.

    2014-12-01

    A new study of the 3-D velocity structure of Taiwan, using a new tomographic model (Vp and Vs; Huang et al., 2014), suggests that subducted continental crust is delaminated from the subducting mantle of the Eurasia plate and progressively deformed by the subducting Philippine Sea plate. In southern Taiwan, vertical sections show an east-dipping, asymmetric lobe of low velocity that projects down dip to a band of seismicity interpreted as the Wadati-Benioff zone of the subducting Eurasian plate. Seismic tremors in the mid-crust also suggest dehydration (Chuang et al., 2014), consistent with prograde metamorphism of crustal materials. In central Taiwan, however, the seismicity of the W-B zone progressively disappears and the low velocity lobe shallows and broadens. The velocity structure of the lower and middle crust (represented by the 7.5 and 6.5 km/sec isovelocity surfaces, respectively) also appear distinctly out-of-phase, with the lower crust forming a broad, smooth synformal structure that contrasts with the higher amplitude undulations of the middle crust. These mid-crust structures appear as smaller irregular lobes separated by patches of higher velocity. In northern Taiwan, the velocity structure of the lower and middle crust again appear "in phase" and form a symmetrical crustal root centered beneath the Central Range. Seismicity patterns and 3-D analysis of the velocity structure also show the western edge of the PSP subducting beneath the eastern Central Range. We interpret these south-to-north changes to reflect the partial subduction (southern Taiwan), delamination (central Taiwan) and deformation (northern Taiwan) of continental-like crust. Support for these interpretation comes from: 1) unusually high rates of surface uplift (up to 15 mm/yr; Ching et al., 2011); 2) Vp and Vs attenuation studies that suggest anomalously high temperatures; 3) evidence for NE-SW extension; and 4) anomalous areas of low topographic relief.

  7. Probing continental collision in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Robertson, A. H. F.

    Knowledge about the processes of continental collisional would unlock a wealth of data for the field of tectonics, but such processes have been poorly documented by academic ocean drilling. On the basis of 1993 data confirming that the easternmost Mediterranean is in the initial stages of continental collision, the Ocean Drilling Program has scheduled two legs of drilling for summer 1995 in the eastern and western parts of the Mediterranean Sea.Effects of continental collision in the easternmost Mediterranean include the Quaternary uplift of Cyprus [Poole and Robertson, 1991] and the break up and subsidence of the Eratosthenes Seamount, which is located in the easternmost Mediterranean between Cyprus and the Levantine Basin (Figure 1).

  8. Collision of continental corner from 3-D numerical modeling

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Hai; Xu, Zhiqin; Gerya, Taras; Burg, Jean-Pierre

    2013-10-01

    Continental collision has been extensively investigated with 2-D numerical models assuming infinitely wide plates or insignificant along-strike deformation in the third dimension. However, the corners of natural collision zones normally have structural characteristics that differ from linear parts of mountain belt. We conducted 3-D high-resolution numerical simulations to study the dynamics of a continental corner (lateral continental/oceanic transition zone) during subduction/collision. The results demonstrate different modes between the oceanic subduction side (continuous subduction and retreating trench) and the continental collision side (slab break-off and topography uplift). Slab break-off occurs at a depth (⩽100 km to ˜300 km) that depends on the convergence velocity. The numerical models produce lateral extrusion of the overriding crust from the collisional side to the subduction side, which is also a phenomenon recognized around natural collision of continental corners, for instance around the western corner of the Arabia-Asia collision zone and around the eastern corner of the India-Asia collision zone. Modeling results also indicate that extrusion tectonics may be driven both from above by the topography and gravitational potentials and from below by the trench retreat and asthenospheric mantle return flow, which supports the link between deep mantle dynamics and shallower crustal deformation.

  9. Switching between alternative responses of the lithosphere to continental collision

    NASA Astrophysics Data System (ADS)

    Baes, Marzieh; Govers, Rob; Wortel, Rinus

    2011-12-01

    We study possible responses to arc-continent or continent-continent collision using numerical models. Our short-term integration models show that the initial stage of deformation following continental collision is governed by the competition between three potential weakness zones: (1) mantle wedge, (2) plate interface and (3) lower continental crust. Depending on which of these is the weakest zone in the system, three different responses can be recognized: (1) subduction polarity reversal, (2) continuation of subduction and (3) delamination and back stepping. Subduction polarity reversal occurs if the mantle wedge is the weakest zone in the system. This happens only if the viscosity of the mantle wedge is at least one order of magnitude lower than the average viscosity of the lithosphere. In continent-continent collision, one additional condition needs to be satisfied for subduction polarity reversal to occur: for the subducting lithosphere the ratio of the viscosity of the lower continental crust to the viscosity of the upper lithospheric mantle must be equal to or higher than 0.006. The time required for polarity reversal depends on several parameters: the convergence rate, the sinking velocity of the detached slab and the relative strength of the mantle wedge, arc and backarc. The response to collision is continued subduction if the plate interface is the weakest zone, and is delamination and back stepping if the lower continental crust is the weakest area in the system. Our finding that a low-viscosity wedge is a prerequisite for a reversal of subduction polarity agrees with inferences about regions for which subduction polarity reversal has been proposed.

  10. Dynamics of continental collision: influence of the plate contact

    NASA Astrophysics Data System (ADS)

    De Franco, Roberta; Govers, Rob; Wortel, Rinus

    2008-09-01

    Observations shows that continental collision may evolve in different ways, resulting in a wide range of tectonic responses. In search of the controlling conditions and parameters, we start from the results of our previous work, which demonstrated that the properties of the plate contact are important for the overall dynamics of convergent plate margins. Two fundamental types of subduction plate contact can be distinguished: one based on a fault and the other based on a weak subduction channel. In this study, we investigate how the plate contact affects the initial stage of continental collision. We use a finite element method to solve the heat and the time-dependent momentum equations for elastic, (power-law) viscous and plastic rheologies. For the same rheological properties and driving forces, varying the nature of the plate contact leads to three types of responses. The presence of a subduction channel promotes coherent and, when the boundary conditions allow it, plate-like subduction of the continental margin. In models with a subduction fault, coherent subduction of the incoming continental lithosphere occurs when the colliding passive margin has a gentle slope. The approaching continental sliver starts to subduct and the subduction is characterized by a non-plate like behaviour-slower subduction velocity than in channel models and strong slab deformation. If the continental margin is steep and the strength of the incoming continental crust is high, fault models result in locking of the trench, eventually leading to slab break-off. If the crustal strength is relatively low, shear delamination of part of the crust is expected. In the channel model, this type of delamination never occurs. The tectonic settings used in our experiments (prescribed plate velocity of the subducting plate versus fixed subducting plate corresponding to a landlocked basin setting) do not significantly influence the nature of the model response. We conclude that initial stages of

  11. Zircon from Mesoproterozoic sediments sheds light on the subduction-collision history at the eastern active continental margin of the Archaean Kalahari-Grunehogna Craton

    NASA Astrophysics Data System (ADS)

    Marschall, H.; Hawkesworth, C. J.; Leat, P. T.; Dhuime, B.; Storey, C.

    2013-12-01

    The Grunehogna Craton (East Antarctica) was a part of the Archean Kalahari Craton of southern Africa prior to Gondwana breakup. Granite from the basement of the craton has been dated by U-Pb zircon dating to 3,067 Ma with inherited grains showing ages of up to 3,433 Ma [1]. At the eastern margin of the craton, the Ahlmannryggen nunataks comprise an ~2000 m thick pile of clastic and volcanic sediments of the Ritscherflya Supergroup. These were sourced from eroding a proximal active continental arc as demonstrated through the age distribution and internal zoning of detrital zircon [2]. Detrital zircon grains from the Ritscherflya Supergroup show an age distribution with a dominant age peak at ~1,130 Ma, i.e., close to the sedimentation age. Older age peaks include those at 1370 Ma, 1725 Ma, 1880 Ma, 2050 Ma, and 2700 Ma. Palaeo- and Mesoarchaean zircon grains (2800-3445 Ma) were also discovered, corresponding to the age of the Kalahari-Grunehogna Craton basement. Most significantly we found a number of inherited Archaean cores in ~1130 Ma zircons. They demonstrate that the volcanic arc was indeed located on Archaean continental crust, rather than in Mesoproterozoic, intra-oceanic island arcs. The age spectrum of the zircons bears strong evidence for (i) derivation of the entire Ritscherflya sediment sequence from an active continental convergent margin; (ii) a cratonic provenance of part of the sediments from population peaks coinciding with major tectono-thermal events in the Kalahari Craton; (iii) at least some of the active volcanism being located on cratonic basement rather than a juvenile island arc. Detrital zircons in the ~1130 Ma age group show several distinct populations in their Hf isotopic compositions. The dominant group shows negative ɛHf values of -11.5 corresponding to a model age (TDM) of ~2700 Ma (average crustal 176Lu/177Hf = 0.015). A smaller group shows ɛHf values of +2 to +6, which may represent mantle-derived subduction-zone volcanism at

  12. The Magnetic Signature of Zones of Continental Collision

    NASA Astrophysics Data System (ADS)

    Purucker, M. E.; Whaler, K. A.

    2007-12-01

    Near-surface and satellite maps of the crustal component of the magnetic field can be interpreted in terms of thermal conditions at depth because the magnetic properties of rocks depend on their temperature. Observations related to continental deformation at diffuse plate boundaries are often considered in relation to three length scales: the thickness of the seismogenic upper crust, the entire continental crust, and the mechanical lithosphere. The lower boundary of the magnetic crust coincides with the Moho, or in the presence of an elevated geotherm, with the Curie isotherm. New global perspectives on the magnetic signature of zones of continental collision are afforded by the recently published Magnetic Anomaly Map of the World (Purucker, 2007, EOS, 88, 263), the MF-5 satellite magnetic field (Maus et al., 2007, Gcubed), and NASA's ST-5 constellation mission in 2006. The thickness of the magnetic crust can be estimated by integrating the MF-5 satellite magnetic field into the 3SMAC compositional and thermal model of the lithosphere, and a minimum estimate of the magnetization can be estimated using a Greens function approach. We compare our magnetic maps with the diffuse plate boundary maps of Gordon (1998) and Dumoulin et al. (1998). The diffuse plate boundary zones exhibit intermediate (22-31 km) magnetic thicknessses, significantly less than those of the adjacent stable plate. The diffuse NE Asia plate boundary zone, from the Lena River delta to the Sea of Okhotsk, is especially well- expressed in both satellite and near-surface magnetic maps.

  13. Development of topography in 3-D continental-collision models

    NASA Astrophysics Data System (ADS)

    Pusok, A. E.; Kaus, Boris J. P.

    2015-05-01

    Understanding the formation and evolution of high mountain belts, such as the Himalayas and the adjacent Tibetan Plateau, has been the focus of many tectonic and numerical models. Here we employ 3-D numerical simulations to investigate the role that subduction, collision, and indentation play on lithosphere dynamics at convergent margins, and to analyze the conditions under which large topographic plateaus can form in an integrated lithospheric and upper mantle-scale model. Distinct dynamics are obtained for the oceanic subduction side (trench retreat, slab rollback) and the continental-collision side (trench advance, slab detachment, topographic uplift, lateral extrusion). We show that slab pull alone is insufficient to generate high topography in the upper plate, and that external forcing and the presence of strong blocks such as the Tarim Basin are necessary to create and shape anomalously high topographic fronts and plateaus. Moreover, scaling is used to predict four different modes of surface expression in continental-collision models: (I) low-amplitude homogeneous shortening, (II) high-amplitude homogeneous shortening, (III) Alpine-type topography with topographic front and low plateau, and (IV) Tibet-Himalaya-type topography with topographic front and high plateau. Results of semianalytical models suggest that the Argand number governs the formation of high topographic fronts, while the amplitude of plateaus is controlled by the initial buoyancy ratio of the upper plate. Applying these results to natural examples, we show that the Alps belong to regime (III), the Himalaya-Tibet to regime (IV), whereas the Andes-Altiplano fall at the boundary between regimes (III) and (IV).

  14. Continental collision zones are primary sites for net continental crust growth — A testable hypothesis

    NASA Astrophysics Data System (ADS)

    Niu, Yaoling; Zhao, Zhidan; Zhu, Di-Cheng; Mo, Xuanxue

    2013-12-01

    The significance of the continental crust (CC) on which we live is self-evident. However, our knowledge remains limited on its origin, its way and rate of growth, and how it has acquired the "andesitic" composition from mantle derived magmas. Compared to rocks formed from mantle derived magmas in all geological environments, volcanic arc rocks associated with seafloor subduction share some common features with the CC; both are relatively depleted in "fluid-insoluble" elements (e.g., Nb, Ta and Ti), but enriched in "fluid-soluble" elements (e.g., U, K and Pb). These chemical characteristics are referred to as the "arc-like signature", and point to a possible link between subduction-zone magmatism and CC formation, thus leading to the "island arc" model widely accepted for the origin of the CC over the past 45 years. However, this "island-arc" model has many difficulties: e.g., (1) the bulk arc crust (AC) is basaltic whereas the bulk CC is andesitic; (2) the AC has variably large Sr excess whereas the CC is weakly Sr deficient; and (3) AC production is mass-balanced by subduction erosion and sediment recycling, thus contributing no net mass to the CC growth, at least in the Phanerozoic. Our recent and ongoing studies on granitoid rocks (both volcanic and intrusive) formed in response to the India-Asia continental collision (~ 55 ± 10 Ma) show remarkable compositional similarity to the bulk CC with the typical "arc-like signature". Also, these syncollisional granitoid rocks exhibit strong mantle isotopic signatures, meaning that they were recently derived from a mantle source. The petrology and geochemistry of these syncollisional granitoid rocks are most consistent with an origin via partial melting of the upper ocean crust (i.e., last fragments of underthrusting ocean crust upon collision) under amphibolite facies conditions, adding net mantle-derived materials to form juvenile CC mass. This leads to the logical and testable hypothesis that continental collision

  15. The relationship between continental collision process and metamorphic pattern in the Himalayan collision belts

    NASA Astrophysics Data System (ADS)

    Oh, Chang-Whan

    2015-04-01

    Both UHP and HP eclogites are reported from the Kaghan Valley and Tso Morari Massif in the western part of the Himalayan collision belt (Ghazanfar and Chaudhry, 1987; Thakur, 1983). UHP eclogites in the Kaghan record peak metamorphic conditions of 770 °C and 30 kbar (O'Brien et al., 2001) and was retrograded into the epidote-amphibolite or blueschist (580-610 °C, 10-13 kbar; Lombardo and Rolfo, 2000). Sensitive high-resolution ion microprobe dating of zircon reveals that the UHP eclogite formed at ca. 46 Ma (Kaneko et al., 2003; Parrish et al., 2006). The Tso Morari UHP eclogite had formed at 750 °C, > 39 kbar (Mukheerjee et al., 2003; Bundy, 1980) and underwent amphibolite facies retro-grade metamorphism (580 °C, 11 kbar) during uplift (Guillot et al., 2008). Peak metamorphism of the Tso Morari Massif was dated at ca. 53-55 Ma (Leech et al., 2005). Only HP eclogites have been reported from the mid-eastern part of the Himalayan collision belt (Lombardo and Rolfo, 2000; Corrie et al., 2010). The HP eclogite in the mid-eastern part may have formed at ca. > 780 °C and 20 kbar and was overprinted by high-pressure granulite facies metamorphism (780-750°C, 12-10 kbar) at ca. 30 Ma (Groppo et al. 2007; Corrie et al., 2010). HP granulite (890 °C, 17-18 kbar) is reported from the NBS, at the eastern terminus of the Himalayan collision belt; the granulite was subjected to retrograde metamorphism to produce lower-pressure granulite (875-850°C, 10-5 kbar), representing near-isothermal decompression (Liu and Zhong, 1997). The HP granulite metamorphism may have occurred at ca. 22-25 Ma. Along the Himalayan collision belt, peak metamorphism changes eastward from UHP eclogite facies through HP eclogite facies to high-pressure granulite facies, indicating a progressive eastwards decrease in the depth of subduction of continental crust and an eastwards increase in the geothermal gradient. The peak metamorphic ages also decrease from 53-46 Ma in the west to 22-25 Ma in the

  16. Thermo-mechanical controls on the mode of continental collision in the SE Carpathians (Romania)

    NASA Astrophysics Data System (ADS)

    Cloetingh, S. A. P. L.; Burov, E.; Matenco, L.; Toussaint, G.; Bertotti, G.; Andriessen, P. A. M.; Wortel, M. J. R.; Spakman, W.

    2004-01-01

    The Carpathians orogenic system, with its along-arc variations in topography developed in the aftermath of continental collision, is associated with unusual foredeep basins, large-scale strain and seismicity concentration and high-velocity mantle bodies. The East Carpathians continental collision was non-cylindrical, leading to large-scale variations in thrust nappe kinematics, orogenic uplift patterns and foredeep subsidence, controlled by the mechanics and geometry of the lower plate. Thermo-mechanical modelling demonstrates that in this low-rate convergence regime, the subducted lithosphere had enough time to interact with the mantle to advance towards a thermal resettlement. This is favored by the low degree of metamorphism, mechanical weakness of the lower plate and the lack of active surface processes at the contact with and in the upper plate. In contrast, low-buoyant, thick lower crust and active surface processes keep the continuity of the slab intact and promote the development of typical foredeep basins. The model explains in a self-consistent manner the unusual geometry of the Vrancea seismogenic slab in the bend zone of the Romanian Carpathians. The model is also consistent with the presence of two high-velocity bodies inferred from seismic tomography studies and explains the depth zonation of seismicity in the Vrancea area. Differences between the northern part of East Carpathians and the southeastern bend of the Carpathians arc are largely controlled by lateral variations in crustal structure, topography emplacement and surface processes along the arc. Mechanical heterogeneity of the Carpathians subduction leads to the development of two end member modes of collision, allowing a study of these states and their transition. Lithospheric configuration and tectonic topography appear to be prime factors controlling variations in slab behavior. In the SE Carpathians, at the terminal phase of continental convergence, slab delamination, roll-back and

  17. Continental subduction induced tremor activity?

    NASA Astrophysics Data System (ADS)

    Tai, H. J.; Chen, K. H.; Ide, S.; Mouyen, M.; Byrne, T. B.

    2015-12-01

    Southern Central Range of Taiwan, a place where deep-seated tectonic tremors (a proxy of slow slip) and earthquake swarms are closely located in space and highly correlated in time, provides rare opportunity towards the understanding of physical mechanisms governing different style of slip. To identify tremor events, we used the identification scheme similar to Ide et al. (2015) but applied slightly different techniques: (1) Higher waveform cross-correlation coefficient (>0.6) (2) careful visual inspection for excluding local earthquakes and short-lasted event (duration < 60 s) (3) Signal to noise ratio higher than 1.2 and lower than 30 (4) No spatio-temporal clustering technique used. During the study period of 2007-2012, we identified 2320 tremor events with duration ranging from 60 s to 1550 s. They are located underneath southern Central Range, forming a NS-striking and SE-dipping pipe-like structure at a depth of 20-40 km. The up-dip extension of this tremor structure reaches an aseismic zone under the western flank of Central Range at shallow depths, where is an area characterized by high heat flow, low Vp and Vs anomaly. Such seismic gap was explained by the buoyancy induced crust detachment during continental subduction of Eurasian Plate. This detachment may open a new channel for hot and ductile material ascending to shallow depth, producing high temperatures along the way. This provides a common mechanism for down-dip tremor and up-dip shallow seismic gap along the same eastern dipping channel. In addition, the tremor events are found to be mostly occurred in high tides and exhibit higher correlation with tide data from west coast of Taiwan. This may again imply the association between tremor activity and subduction of Eurasian Plate.

  18. Influence of Earth crust composition on continental collision style in Precambrian conditions: Results of supercomputer modelling

    NASA Astrophysics Data System (ADS)

    Zavyalov, Sergey; Zakharov, Vladimir

    2016-04-01

    A number of issues concerning Precambrian geodynamics still remain unsolved because of uncertainity of many physical (thermal regime, lithosphere thickness, crust thickness, etc.) and chemical (mantle composition, crust composition) parameters, which differed considerably comparing to the present day values. In this work, we show results of numerical supercomputations based on petrological and thermomechanical 2D model, which simulates the process of collision between two continental plates, each 80-160 km thick, with various convergence rates ranging from 5 to 15 cm/year. In the model, the upper mantle temperature is 150-200 ⁰C higher than the modern value, while the continental crust radiogenic heat production is higher than the present value by the factor of 1.5. These settings correspond to Archean conditions. The present study investigates the dependence of collision style on various continental crust parameters, especially on crust composition. The 3 following archetypal settings of continental crust composition are examined: 1) completely felsic continental crust; 2) basic lower crust and felsic upper crust; 3) basic upper crust and felsic lower crust (hereinafter referred to as inverted crust). Modeling results show that collision with completely felsic crust is unlikely. In the case of basic lower crust, a continental subduction and subsequent continental rocks exhumation can take place. Therefore, formation of ultra-high pressure metamorphic rocks is possible. Continental subduction also occurs in the case of inverted continental crust. However, in the latter case, the exhumation of felsic rocks is blocked by upper basic layer and their subsequent interaction depends on their volume ratio. Thus, if the total inverted crust thickness is about 15 km and the thicknesses of the two layers are equal, felsic rocks cannot be exhumed. If the total thickness is 30 to 40 km and that of the felsic layer is 20 to 25 km, it breaks through the basic layer leading to

  19. Cutting of the European continental lithosphere: Plasticity theory applied to the present Alpine collision

    NASA Astrophysics Data System (ADS)

    Regenauer-Lieb, Klaus; Petit, Jean-Pierre

    1997-04-01

    Presently active European Alpine collision has a history of more than 100 Myr convergence. We investigate the collisional contact problem of an apparently rigid African promontory (currently the Italy/Adria block (IAB)) steadily penetrating at 1 cm/yr, over at least the past 45 Myr, into the deformable European plate. We assume that neither continental subduction nor delamination occurs presently in the 300-km-wide contact zone enabling use of the indenter-indentee approach. A key parameter is the aspect ratio h/a, defined by the width of the deformable foreland over the width of the indenter itself. This parameter controls the activation of two fundamentally different modes of deformation: (1) classical indentation mode for h/a≥4.4, described by previous authors, and having effect only in a portion of the deformable plate in the vicinity of the indenter and (2) cutting mode for h/a<4.4 giving plane strain longitudinal splitting of the entire deformable plate and plastic separation of the two halves. We use a matrix operator method to solve for slip lines in the mixed boundary value problem (obliquity, velocity, friction, stress) of the European Alpine case. Implications are as follows: (1) plane stress, vertical lithospheric thickening is the first indentation mode of continental collision; and (2) for the present ratio of h/a≈3 deformation is in the cutting mode and slow plane strain intraplate extension (rifting) is predicted. This mode explains the intraplate stress field obtained from borehole and earthquake data. Considering that the paleoindenter probably has been larger than the IAB it is inferred that h/a has been below 4.4 since at least the end of the Eocene and that consequently the intraplate graben system (Lower Rhine, Rhine, Bresse, Limagne) is due to the cutting of the European plate by Alpine collision.

  20. From Oceanic Lithosphere Subduction To Continental Collision: Influence Of The Plate Contact

    NASA Astrophysics Data System (ADS)

    de Franco, R.; Govers, R.; Wortel, R.

    2004-12-01

    We showed recently that the overall dynamics of oceanic subduction differ depending on whether the plate contact is a fault or a channel (De Franco & al., 2007. GJI, doi: 10.1111/j.1365-246X.2006.03498.x). Here we investigate how the plate contact affects the transition from oceanic lithosphere subduction to continental collision. We use a finite element method to solve the heat and the time dependent momentum equations for elastic, (power law) viscous and plastic rheologies. For the same rheological properties and driving forces , varying the nature of the plate contact leads to three types of responses: subduction of the entire continental lithosphere, shear delamination of the continental crust or slab break-off. We make the following observations from our numerical experiments. The presence of a subduction channel promotes coherent and, when the boundary conditions allow it, plate-like subduction of the continental margin. In models with a subduction fault, coherent subduction of the incoming continental lithosphere occurs when the colliding passive margin has a gentle ocean-continent transition. The approaching continental sliver starts to subduct and the subduction is characterized by a non-plate-like behavior, slower subduction velocity than in channel models and strong slab deformation. If the continental margin is steep and the strength of the incoming continental crust is high, fault models result in locking of the trench, eventually leading to slab break-off. If the crustal strength is relatively low, shear delamination of the upper crust is expected. In the channel model this type of delamination never occurs. The tectonic setting does not significantly affect the nature of the model response. We conclude that the plate contact type, together with the geometrical and rheological properties of the incoming continental fragment, is a crucial subduction characteristic controlling the response of continental collision during the transition from oceanic

  1. From Oceanic Lithosphere Subduction To Continental Collision: Influence Of The Plate Contact

    NASA Astrophysics Data System (ADS)

    de Franco, R.; Govers, R.; Wortel, R.

    2007-12-01

    We showed recently that the overall dynamics of oceanic subduction differ depending on whether the plate contact is a fault or a channel (De Franco & al., 2007. GJI, doi: 10.1111/j.1365-246X.2006.03498.x). Here we investigate how the plate contact affects the transition from oceanic lithosphere subduction to continental collision. We use a finite element method to solve the heat and the time dependent momentum equations for elastic, (power law) viscous and plastic rheologies. For the same rheological properties and driving forces , varying the nature of the plate contact leads to three types of responses: subduction of the entire continental lithosphere, shear delamination of the continental crust or slab break-off. We make the following observations from our numerical experiments. The presence of a subduction channel promotes coherent and, when the boundary conditions allow it, plate-like subduction of the continental margin. In models with a subduction fault, coherent subduction of the incoming continental lithosphere occurs when the colliding passive margin has a gentle ocean-continent transition. The approaching continental sliver starts to subduct and the subduction is characterized by a non-plate-like behavior, slower subduction velocity than in channel models and strong slab deformation. If the continental margin is steep and the strength of the incoming continental crust is high, fault models result in locking of the trench, eventually leading to slab break-off. If the crustal strength is relatively low, shear delamination of the upper crust is expected. In the channel model this type of delamination never occurs. The tectonic setting does not significantly affect the nature of the model response. We conclude that the plate contact type, together with the geometrical and rheological properties of the incoming continental fragment, is a crucial subduction characteristic controlling the response of continental collision during the transition from oceanic

  2. Partial melting, fluid supercriticality and element mobility in ultrahigh-pressure metamorphic rocks during continental collision

    NASA Astrophysics Data System (ADS)

    Zheng, Yong-Fei; Xia, Qiong-Xia; Chen, Ren-Xu; Gao, Xiao-Ying

    2011-08-01

    Partial melting at continental lithosphere depths plays an important role in generating geochemical variations in igneous rocks. In particular, dehydration melting of ultrahigh-pressure (UHP) metamorphic rocks during continental collision provides a petrological link to intracrustal differentiation with respect to the compositional evolution of continental crust. While island arc magmatism represents one end-member of fluid-induced large-scale melting in the mantle wedge during subduction of the oceanic crust, the partial melting of UHP rocks can be viewed as the other end-member of fluid-induced small-scale anatexis during exhumation of the deeply subducted continental crust. This latter type of melting is also triggered by metamorphic dehydration in response to P-T changes during the continental collision. It results in local occurrences of hydrous melts (even supercritical fluids) as felsic veinlets between boundaries of and multiphase solid inclusions in UHP metamorphic minerals as well as local accumulation of veinlet-like felsic leucosomes in foliated UHP metamorphic rocks and metamorphically grown zircons in orogenic peridotites. Thus, very low-degree melts of UHP rocks provide a window into magmatic processes that operated in continental subduction zones. This article presents a review on available results from experimental petrology concerning the possibility of partial melting under conditions of continental subduction-zone metamorphism, and petrological evidence for the occurrence of dehydration-driven in-situ partial melting in natural UHP rocks during the continental collision. Although the deeply subducted continental crust is characterized by a relative lack of aqueous fluids, the partial melting in UHP rocks commonly takes place during decompression exhumation to result in local in-situ occurrences of felsic melts at small scales. This is caused by the local accumulation of aqueous fluids due to the breakdown of hydrous minerals and the exsolution

  3. Sub-lithospheric small scale convection - a process for continental collision magmatism

    NASA Astrophysics Data System (ADS)

    Kaislaniemi, Lars; van Hunen, Jeroen; Allen, Mark; Neill, Iain

    2014-05-01

    We have studied the role of sub-lithospheric small scale convection in the generation of collision zone magmatism, using combined geodynamic-petrological models. We compare the results with the collisional magmatism of the Turkish-Iranian plateau, where a number of randomly (in both space and time) distributed volcanic centres on has been produced by the active Arabia-Eurasia collision since initial plate collision at ~27-35 Ma. These volcanic rocks have a highly variable geochemical signature, but commonly point to a lithospheric mantle or asthenospheric source. Major and trace element characteristics span the range from OIB-like, to calc-alkali, shoshonitic and even ultrapotassic. We suggest these spatially, temporally and chemically diverse patterns of volcanism are caused by sub-lithospheric small scale convection (SSC), manifested as small (50 to 300 km) convection cells at the lithosphere-asthenosphere boundary and dripping of the lithospheric mantle into the asthenosphere. SSC is activated by the increased amount of water in the lithospheric and asthenospheric mantle and its rheological weakening effect. The increase in water content is caused by the subduction prior to the collision and/or continental subduction during collision. The mantle convection code CitCom, together with a parameterized melting model, is used to model the SSC process. We relate the water content to the mantle solidus and viscosity, and the amount of depletion to the viscosity and buoyancy of the mantle material. We measure the amount of magmatism taking place by assuming direct and instantaneous percolation of mantle melts to the surface. We mimic the dislocation creep mechanism with a diffusion creep mechanism using low activation energy--either one is needed for the SSC to take place under realistic conditions. Results show that SSC is able to produce small degrees (0-2 %) of melting of the mantle through dripping lithosphere, decompression melting, erosion of the overlying

  4. Tomographic Pn and Sn velocity beneath the continental collision zone from Alps to Himalaya

    NASA Astrophysics Data System (ADS)

    Pei, Shunping; Sun, Youshun; ToksöZ, M. Nafi

    2011-10-01

    We have obtained Vp and Vs velocity images of the uppermost mantle beneath the continental collision zone from the Alps to the Himalaya by performing tomographic inversion using both Pn and Sn travel times. 654,999 Pn arrivals and 121,838 Sn arrivals were selected from the joint database including ISC/EHB, Iran bulletin and the Annual Bulletin of Chinese Earthquakes. Average Pn and Sn velocities are 8.04 km/s and 4.60 km/s, respectively, and maximum velocity perturbations are about 6%. Pn velocity correlates well with topography. In general, mountains, with high elevations, show low velocity, while the seas, basins and plains with low elevations show high velocity because the mountains are collision zones with strong tectonic activity and the low elevation areas are stable plates. The large tectonic lines are boundaries between high and low Pn velocity, such as plate boundaries, sutures and faults between plates and orogens. Sn velocity shows a very similar pattern to Pn velocity. A geodynamic cartoon is proposed to show the relationship between velocity and tectonics, indicating that the sutures are boundaries with high dip angles and the plate boundaries are low angle reverse faults in the region.

  5. Repeated arc-continent collision as a key mechanism for continental growth

    NASA Astrophysics Data System (ADS)

    Aitchison, J.; Buckman, S.

    2011-12-01

    Prevailing 'consensus' models for the Phanerozoic development of eastern Australia invoke a retreating accretionary orogen model in which slab retreat results in development of offshore island arcs in front of marginal basins. Periodically these basins close and the arcs are retro-thrust back onto the continental margin. Implicit in this model is the notion that all elements develop in an upper plate location upon the accretionary margin and that west-dipping subduction beneath eastern Gondwana was a long-lived phenomenon. We suggest this concept is flawed and instead propose a new testable hypothesis that eastern Australia grew through a series of arc-continent collisions in which east-directed subduction beneath intra-oceanic island arcs led to their collision with eastern Australia. At least four such arc-continent collisions are posited in mid-Cambrian (Mt Stavely arc), Late Ordovician (Macquarie arc), mid-Devonian (Gamilaroi arc) and Late Permian (Gympie arc) times. This process effectively transferred new material to the continental crust resulting in net growth. When collisions were followed by subduction flip episodes of west-directed subduction beneath the continental margin ensued giving rise to the S- and I-type granites for which eastern Australia is famous.

  6. Kinematics of late Paleozoic continental collision between Laurentia and Gondwana

    USGS Publications Warehouse

    Sacks, P.E.; Secor, D.T., Jr.

    1990-01-01

    In the Appalachians, late Paleozoic Alleghanian orogenesis is widely regarded as resulting from dextral oblique collision between irregular margins of Gondwana and Laurentia. However, this relative plate motion cannot account for coeval convergence in the Ouachitas and Variscides and is incompatible with some tectonic transport indicators in the Appalachians. An alternative kinematic model is proposed in which early sinistral transpression in the Appalachians is followed by counterclockwise rotation of Gondwana and the development of a system of dextral strike-slip faults extending from southern Europe to Alabama.

  7. Continental Collision Zones are Primary Sites of net Continental Crustal Growth: Evidence From the Linzizong Volcanic Succession in Southern Tibet

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Mo, X.; Dong, G.; Zhao, Z.; Hou, Z.; Zhou, S.; Ke, S.

    2007-12-01

    The Linzizong volcanics (ca. 65-45Ma) and the coeval batholiths (ca. 60-40Ma) of andesitic-to-rhyolitic composition are magmatic response to the India-Asia continental collision that began at ca. 70-65Ma and ended at ca. 45-40Ma with convergence continuing to present [1,2]. These syncollisional magmatic rocks are widely distributed along much of the >1500km long Gangdese Belt immediately north of the India-Asia suture (Yarlung-Zangbo) in southern Tibet [2-6]. Our study of the Linzizong volcanics from the Linzhou Basin (near Lhasa) encourages the proposal that syncollisional granitoid magmatism may in fact account for much of the net contribution to continental crust growth. The Linzizong volcanics in the Linzhou Basin show a first-order temporal change from the lower andesitic formation (64.4-60.6Ma), to the middle dacitic formation (ca. 54Ma), and to the upper rhyolitic formation (48.7-43.9Ma). The three formations show no systematic but overlapping Nd-Sr isotope variations. The isotopically depleted samples with ɛNd(t)>0 (up to + 8) indicate that their primary sources are of mantle origin. The best source candidate in the broad context of Tethyan ocean closing and India- Asia collision is the remaining part of the Tethyan ocean crust [6]. This ocean crust melts when reaching its hydrous solidus during and soon after the collision in the amphibolite facies, producing andesitic melts parental to the Linzizong volcanics (also the coeval batholiths) with inherited mantle isotopic signatures [6]. Ilmenite is abundant in amphibolite [7], and partial melting of amphibolite with ilmenite as a residual phase accounts for the depletion of Nb, Ta and Ti in the melt. The effect of ocean crust alteration plus involvement of mature crustal materials (e.g., recycled terrigeneous sediments) enhances the elevated abundances of Ba, Rb, Th, U, K and Pb in the melt [8,9]. These give the syncolissional Linzizong volcanics characteristic "arc-like" geochemical signature. Residual

  8. Continental collision slowing due to viscous mantle lithosphere rather than topography.

    PubMed

    Clark, Marin Kristen

    2012-03-01

    Because the inertia of tectonic plates is negligible, plate velocities result from the balance of forces acting at plate margins and along their base. Observations of past plate motion derived from marine magnetic anomalies provide evidence of how continental deformation may contribute to plate driving forces. A decrease in convergence rate at the inception of continental collision is expected because of the greater buoyancy of continental than oceanic lithosphere, but post-collisional rates are less well understood. Slowing of convergence has generally been attributed to the development of high topography that further resists convergent motion; however, the role of deforming continental mantle lithosphere on plate motions has not previously been considered. Here I show that the rate of India's penetration into Eurasia has decreased exponentially since their collision. The exponential decrease in convergence rate suggests that contractional strain across Tibet has been constant throughout the collision at a rate of 7.03 × 10(-16) s(-1), which matches the current rate. A constant bulk strain rate of the orogen suggests that convergent motion is resisted by constant average stress (constant force) applied to a relatively uniform layer or interface at depth. This finding follows new evidence that the mantle lithosphere beneath Tibet is intact, which supports the interpretation that the long-term strain history of Tibet reflects deformation of the mantle lithosphere. Under conditions of constant stress and strength, the deforming continental lithosphere creates a type of viscous resistance that affects plate motion irrespective of how topography evolved. PMID:22382982

  9. Strong Lg-wave attenuation in the Middle East continental collision orogenic belt

    NASA Astrophysics Data System (ADS)

    Zhao, Lian-Feng; Xie, Xiao-Bi

    2016-04-01

    Using Lg-wave Q tomography, we construct a broadband crustal attenuation model for the Middle East. The QLg images reveal a relationship between attenuation and geological structures. Strong attenuation is found in the continental collision orogenic belt that extends from the Turkish and Iranian plateau to the Pamir plateau. We investigate the frequency dependence of QLg in different geologic formations. The results illustrate that QLg values generally increase with increasing frequency but exhibit complex relationships both with frequency and between regions. An average QLg value between 0.2 and 2.0 Hz, QLg (0.2-2.0 Hz), may be a critical index for crustal attenuation and is used to infer the regional geology. Low-QLg anomalies are present in the eastern Turkish plateau and correlate well with low Pn-velocities and Cenozoic volcanic activity, thus indicating possible partial melting within the crust in this region. Very strong attenuation is also observed in central Iran, the Afghanistan block, and the southern Caspian Sea. This in line with the previously observed high crustal temperature, high-conductivity layers, and thick marine sediments in these areas, suggests the high Lg attenuation is caused by abnormally high tectonic and thermal activities.

  10. Effects of rheology on the dynamics and development of topography in 3D numerical simulations of continental collision, with an application to the India-Asia collision zone

    NASA Astrophysics Data System (ADS)

    Pusok, A. E.; Kaus, B.; Popov, A.

    2014-12-01

    The Himalayas and the adjacent Tibetan Plateau represent the largest region of elevated topography and anomalously thick crust on Earth. Understanding the formation and evolution of the region has been the focus of many tectonic and numerical models. While some of these models (i.e. thin sheet model) have successfully illustrated some of the basic physics of continental collision, none can simultaneously represent active processes such as subduction, underthrusting, channel flow or extrusion, for which fully 3D models are required. Here, we employed the 3D code LaMEM to investigate the role that subduction, continental collision and indentation play on lithosphere dynamics at convergent margins, and the implications they have for the Asian tectonics. Our model setup resembles a simplified tectonic map of the India-Asia collision zone and we performed a large number of 3D simulations to analyse the dynamics and the conditions under which large topographic plateaus, such as the Tibetan Plateau can form in an integrated lithospheric and upper-mantle scale model. Results of models with linear viscous rheologies show different modes between the oceanic subduction side (continuous subduction, trench retreat and slab roll-back) and the continental collision side (trench advance, slab detachment, topographic uplift and lateral extrusion of material). Despite the complex dynamics and the great variation in slab shape across the subduction-collision zone, which are consistent with tomographic observations, we note that slab-pull alone is insufficient to generate high topography in the upper plate. Several studies suggested that external forces (i.e. ridge push, plume push or slab suction) must be important in order to sustain the on-going convergence of India towards Eurasia. We show that external forcing and the presence of strong blocks such as the Tarim Basin within the Asian lithosphere are necessary to create and shape anomalously high topographic fronts and plateaus

  11. The 3-D dynamics of slab break-off and implications for continental collision zones

    NASA Astrophysics Data System (ADS)

    van Hunen, Jeroen; Allen, Mark

    2010-05-01

    Some of the world best studied mountain ranges are a result of continental collision, such as the Himalayas, Zagros mountains, and the Alps. Continental collision forms the last stage of the closure of an oceanic basin, and leads to the slow-down or complete cessation of the subduction process. Previously subducted slab material will experience a period of thermal warming (Gerya et al., 2004) and/or a larger tensile stress, and will eventually weaken, yield and sink into the mantle. This process has potentially important implications for the thermal and stress regime of the overlying convergence zone, and has been held responsible for various phenomena such as late-stage magmatism (Davies and von Blanckenburg, 1995) and surface uplift or depression (van der Meulen et al., 1998, Buiter et al., 2002). Even though the collision process itself is relatively short-lived compared to the preceding oceanic subduction, its remnants are often preserved, and probably provide a valuable window into the plate tectonic process during the Proterozoic and perhaps the Archaean (e.g. Calvert et al., 1995). The three-dimensional nature of this break-off process has previously been discussed with conceptual models. E.g. slab break-off has been suggested to propagate laterally through an advancing tear (Wortel and Spakman, 2000). In this study we present 3D numerical results of the evolution of slab break-off. We focus on the development and evolution of a laterally migrating slab tear, and present results on the sensitivity of this process to the geometry of the closing oceanic basin, the tensile stresses in and the rheological properties of the slab, and the thermal state of the surrounding mantle. By comparing our numerical results to previously published analogue results (Regard et al., 2004) and various tomographic, structural, and magmatic observations of well-studied subduction collision systems, we are able to extract valuable insights in to the dynamics and strength of

  12. Slab detachment during continental collision: Influence of crustal rheology and interaction with lithospheric delamination

    NASA Astrophysics Data System (ADS)

    Duretz, T.; Gerya, T. V.

    2013-08-01

    Collision between continents can lead to the subduction of continental material. If the crust remains coupled to the downgoing slab, a large buoyancy force is generated. This force slows down convergence and promotes slab detachment. If the crust resists to subduction, it may decouple from the downgoing slab and be subjected to buoyant extrusion. We employ two-dimensional thermo-mechanical modelling to study the importance of crustal rheology on the evolution of subduction-collision systems. We propose simple quantifications of the mechanical decoupling between lithospheric levels (σ*) and the potential for buoyant extrusion of the crust (ξ*). The modelling results indicate that a variable crustal rheological structure results in slab detachment, delamination, or the combination of both mechanisms. A strong crust provides coupling at the Moho (low σ*) and remains coherent during subduction (low ξ). It promotes deep subduction of the crust (180 km) and slab detachment. Exhumation occurs in coherent manners via eduction and thrusting. Slab detachment triggers the development of topography (> 4.5 km) close to the suture. A contrasting style of collision occurs using a weak crustal rheology. Mechanical decoupling at the Moho (high σ*) promotes the extrusion of the crust (high ξ), disabling slab detachment. Ongoing shortening leads to buckling of the crust and development of topography on the lower plate. Collisions involving rheologically layered crust allow decoupling at mid-crustal depths. This structure favours both the extrusion of upper crust and the subduction of the lower crust. Such collisions are successively affected by delamination and slab detachment. Topography develops together with the buoyant extrusion of crust onto the foreland and is further amplified by slab detachment. Our results suggest that the occurrence of both delamination (Apennines) and slab detachment (Himalayas) in orogens may indicate differences in the initial crustal structure of

  13. Topographic Evolution and Climate Aridification during Continental Collision: Insights from Computer Simulations.

    PubMed

    Garcia-Castellanos, Daniel; Jiménez-Munt, Ivone

    2015-01-01

    How do the feedbacks between tectonics, sediment transport and climate work to shape the topographic evolution of the Earth? This question has been widely addressed via numerical models constrained with thermochronological and geomorphological data at scales ranging from local to orogenic. Here we present a novel numerical model that aims at reproducing the interaction between these processes at the continental scale. For this purpose, we combine in a single computer program: 1) a thin-sheet viscous model of continental deformation; 2) a stream-power surface-transport approach; 3) flexural isostasy allowing for the formation of large sedimentary foreland basins; and 4) an orographic precipitation model that reproduces basic climatic effects such as continentality and rain shadow. We quantify the feedbacks between these processes in a synthetic scenario inspired by the India-Asia collision and the growth of the Tibetan Plateau. We identify a feedback between erosion and crustal thickening leading locally to a <50% increase in deformation rates in places where orographic precipitation is concentrated. This climatically-enhanced deformation takes place preferentially at the upwind flank of the growing plateau, specially at the corners of the indenter (syntaxes). We hypothesize that this may provide clues for better understanding the mechanisms underlying the intriguing tectonic aneurisms documented in the Himalayas. At the continental scale, however, the overall distribution of topographic basins and ranges seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent. The dry climatic conditions that naturally develop in the interior of the continent, for example, trigger large intra-continental sediment trapping at basins similar to the Tarim Basin because they determine its endorheic/exorheic drainage. These complex climatic-drainage-tectonic interactions make the

  14. Topographic Evolution and Climate Aridification during Continental Collision: Insights from Computer Simulations

    PubMed Central

    2015-01-01

    How do the feedbacks between tectonics, sediment transport and climate work to shape the topographic evolution of the Earth? This question has been widely addressed via numerical models constrained with thermochronological and geomorphological data at scales ranging from local to orogenic. Here we present a novel numerical model that aims at reproducing the interaction between these processes at the continental scale. For this purpose, we combine in a single computer program: 1) a thin-sheet viscous model of continental deformation; 2) a stream-power surface-transport approach; 3) flexural isostasy allowing for the formation of large sedimentary foreland basins; and 4) an orographic precipitation model that reproduces basic climatic effects such as continentality and rain shadow. We quantify the feedbacks between these processes in a synthetic scenario inspired by the India-Asia collision and the growth of the Tibetan Plateau. We identify a feedback between erosion and crustal thickening leading locally to a <50% increase in deformation rates in places where orographic precipitation is concentrated. This climatically-enhanced deformation takes place preferentially at the upwind flank of the growing plateau, specially at the corners of the indenter (syntaxes). We hypothesize that this may provide clues for better understanding the mechanisms underlying the intriguing tectonic aneurisms documented in the Himalayas. At the continental scale, however, the overall distribution of topographic basins and ranges seems insensitive to climatic factors, despite these do have important, sometimes counterintuitive effects on the amount of sediments trapped within the continent. The dry climatic conditions that naturally develop in the interior of the continent, for example, trigger large intra-continental sediment trapping at basins similar to the Tarim Basin because they determine its endorheic/exorheic drainage. These complex climatic-drainage-tectonic interactions make the

  15. Subduction-related metamorphism beneath ophiolites (Oman) and during early stages of continental collision (Himalaya)

    NASA Astrophysics Data System (ADS)

    Searle, Mike; Waters, David; Cowan, Robert; Cherry, Alan; Cooper, Charles

    2014-05-01

    Subduction-related metamorphism occurs beneath ophiolites (Oman), beneath island arcs (Kohistan) and during the early stages of continental collision (Kaghan, Tso Morari; Himalaya). Ophiolite obduction necessarily involves subduction of first oceanic, then continental crust to mantle depths beneath the ophiolite. In Oman an inverted pressure and temperature profile is exposed beneath the Semail ophiolite from garnet+clinopyroxene-bearing granulite to hornblende+plagioclase amphibolite down through epidote amphibolite and a variety of greenschist facies meta-sediments, dominantly cherts, marbles and quartzites. Thermobarometry on Grt+Cpx-bearing amphibolites immediately beneath the contact with mantle sequence harzburgites shows that the upper sole rocks formed at PT conditions of 770-900°C and 11-13 kbar, equivalent to depths of 30-40 km in oceanic lithosphere. Heat for metamorphism can only have been derived from the overlying mantle peridotites. Pressures are higher than can be accounted for by the thickness of the preserved ophiolite (15-20 km). Timing of peak metamorphism was synchronous with formation of the ophiolite gabbroic - trondhjemite crustal sequence and eruption of the pillow lavas (Cenomanian; 96-95 Ma). During the later stages of obduction the continental margin was dragged down to depths of nearly 100 km and basaltic sills within calc-schists were converted to eclogites (20-25 kbar; 500-560oC; 79.1 Ma), then exhumed back up the same subduction channel. Apparent 'extensional' fabrics throughout the HP units are related to upward flow of deeply buried rocks in a wholly compressional environment. Eclogites in a similar structural position occur along the Himalaya in the northernmost exposures of Indian plate rocks. These eclogites formed either during the latest stage of ophiolite obduction or the earliest stage of continental collision.

  16. Seismic structure and dynamics of cratons: Stability and modification, continental collision and subduction

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergei; Meier, Thomas; Schaeffer, Andrew J.; Agius, Matthew R.; Adam, Joanne M.-C.

    2014-05-01

    relatively low shear-wave speeds in the mantle lithosphere. This anomaly is present in regions of both Proterozoic and Archean crust, which suggests an alteration of the mantle lithosphere after the formation of the cratons. In orogenies, cratons generally resist deformation and subduction. Collisions of cratonic blocks, such as seen presently in the western part of the India-Asia convergence zone, can change the character of the orogeny, as well as the motions of the entire tectonic plates that are converging. Beneath western Tibet, cratonic Indian lithosphere has been stripped of its upper crust, pushed down underneath the thick Tibetan crust, and is now colliding with the Tarim Craton to the north. This recent deepening of the cold Indian lithosphere explains the exceptionally high shear speeds (up to 5.0 km/s) within it, higher than beneath any stable cratons with steady-state geotherms. High-velocity anomalies beneath central and eastern Tibet require negative thermal anomalies of hundreds of degrees at depths below 120-150 km, indicating, most likely, subducted Indian lithosphere. The active India-Asia convergence zone thus demonstrates different mechanisms of continental convergence, from craton-craton collision to underthrusting of a craton beneath thick orogenic crust and to shallow-angle subduction of cratonic lithosphere. References Agius, M. R., S. Lebedev. Tibetan and Indian lithospheres in the upper mantle beneath Tibet: Evidence from broadband surface-wave dispersion. Geochem. Geophys. Geosyst. 14, 4260-4281, doi:10.1002/ggge.20274, 2013. Legendre, C., T. Meier, S. Lebedev, W. Friederich, L. Viereck-Goette. A shear-wave velocity model of the European upper mantle from automated inversion of seismic shear and surface waveforms. Geophys. J. Int. 191, 282-304, 2012. Schaeffer, A. J., S. Lebedev. Global shear-speed structure of the upper mantle and transition zone. Geophys. J. Int. 194, 417-449, 2013.

  17. Continental block collision in the eastern arm of Sulawesi (Indonesia). Structure and geodynamic interpretationCollision de blocs continentaux dans le bras est de Sulawesi (Indonésie). Structure et interprétation géodynamique.

    NASA Astrophysics Data System (ADS)

    Villeneuve, Michel; Cornée, Jean-Jacques; Gunawan, Wahyu; Janin, Marie-Christine; Butterlin, Jacques; Saint-Marc, Pierre; Samodra, Hanang

    2000-03-01

    Recent investigations in East Indonesia lead us to consider the eastern arm of Sulawesi as the result of a collision between two continental blocks: the Tokala block to the west and the Banggai-Sula block to the east. The Tokala block results from the Oligocene obduction of an ophiolitic Asiatic basin onto the passive margin of a Gondwanian block (Banda block), with collision with the Asiatic active margin (western arm of Sulawesi) near the end of the Oligocene or at the beginning of the Miocene. The Tokala Block was then collided by the Irian Jaya derived Banggai-Sula block in the Early to Middle Pliocene times or later.

  18. Database of Active Structures From the Indo-Asian Collision

    NASA Astrophysics Data System (ADS)

    Styron, Richard; Taylor, Michael; Okoronkwo, Kelechi

    2010-05-01

    The ongoing collision of India and Asia has produced a vast system of folds and faults, many of which are active today, as evidenced by such recent deadly earthquakes as the 12 May 2008 Sichuan quake [Parsons et al., 2008]. Understanding these events requires knowledge of the region’s geologic structures. Taylor and Yin [2009] have assembled HimaTibetMap-1.0, a multiformat, comprehensive database of first-order active structures in central Asia that may aid researchers, educators, and students in their studies of Indo-Asian tectonics. For example, this database may be used by seismologists, geodesists, and modelers to identify structures in particular locations that contribute to active deformation, or it may be used by teachers to illustrate concepts such as continental collision or distributed deformation of continents.

  19. Lithospheric-scale geoelectrical characterisation of a continental collision zone in Pyrenees: preliminary results.

    NASA Astrophysics Data System (ADS)

    Campanyà, J.; Ledo, J.; Queralt, P.; Marcuello, A.; Liesa, M.; Muñoz, J. A.; Jones, A. G.

    2012-04-01

    Continental collision orogenic systems, responsible of large mountains ranges like the Himalaya and the Alps, play a primary role in the development of the continents creating, shaping and destroying the lithosphere over millions of years. A particular case of continental collision between the Iberian and European plates resulted in the Pyrenees during the Alpine orogeny. The significant amount of available geophysical data and the well-constrained geological evolution make this mountain chain an ideal area to study orogenic processes. Although the geological evolution is as well constrained as possible from surface and crustal geophysics, lithospheric-scale physical processes are less well characterised and their interpretations differ significantly. To aid understanding of this orogen we have undertaken a series of magnetotelluric studies with the latest in 2011. In total, data at 70 broadband magnetotelluric (BBMT) sites and 27 long period magnetotelluric (LMT) sites were recorded in the Pyrenees, mixing old BBMT data with new BBMT and LMT data. Sites are distributed on four along-strike profiles from the Eastern to the Western part of the Pyrenees that border France and Spain. Each profile crosses the mountain range approximately from south to north and their lengths are from 70 km, the shortest, to 180 km, the longest. Additionally, some sites were located between MT profiles helping to constrain the three-dimensional geometries of the geoelectrical structures inbetween them. The geoelectrical information obtained from MT data is independent of other physical properties typically analyzed in lithospheric studies like density and velocity anomaly. Comparison of the MT data with independent available geological and geophysical data helps us to determine better the geological and physical processes of the study area. The results obtained in this study characterise the geological structures and the physical properties of the Pyrenees at lithospheric scale and

  20. Temporal evolution of continental lithospheric strength in actively deforming regions

    USGS Publications Warehouse

    Thatcher, W.; Pollitz, F.F.

    2008-01-01

    It has been agreed for nearly a century that a strong, load-bearing outer layer of earth is required to support mountain ranges, transmit stresses to deform active regions and store elastic strain to generate earthquakes. However the dept and extent of this strong layer remain controversial. Here we use a variety of observations to infer the distribution of lithospheric strength in the active western United States from seismic to steady-state time scales. We use evidence from post-seismic transient and earthquake cycle deformation reservoir loading glacio-isostatic adjustment, and lithosphere isostatic adjustment to large surface and subsurface loads. The nearly perfectly elastic behavior of Earth's crust and mantle at the time scale of seismic wave propagation evolves to that of a strong, elastic crust and weak, ductile upper mantle lithosphere at both earthquake cycle (EC, ???10?? to 103 yr) and glacio-isostatic adjustment (GIA, ???103 to 104 yr) time scales. Topography and gravity field correlations indicate that lithosphere isostatic adjustment (LIA) on ???106-107 yr time scales occurs with most lithospheric stress supported by an upper crust overlying a much weaker ductile subtrate. These comparisons suggest that the upper mantle lithosphere is weaker than the crust at all time scales longer than seismic. In contrast, the lower crust has a chameleon-like behavior, strong at EC and GIA time scales and weak for LIA and steady-state deformation processes. The lower crust might even take on a third identity in regions of rapid crustal extension or continental collision, where anomalously high temperatures may lead to large-scale ductile flow in a lower crustal layer that is locally weaker than the upper mantle. Modeling of lithospheric processes in active regions thus cannot use a one-size-fits-all prescription of rheological layering (relation between applied stress and deformation as a function of depth) but must be tailored to the time scale and tectonic

  1. Geodynamic constraints on stress and strength of the continental lithosphere during India-Asia collision.

    NASA Astrophysics Data System (ADS)

    Kaus, B. J. P.; Schmalholz, S. M.; Lebedev, S.; Deschamps, F.

    2009-04-01

    There has been quite some debate in recent years on what the long-term strength of the continental lithosphere is and how it is related to the occurrence of earthquakes. One of the best studied areas in this respect is the India-Asia collision zone, where -in some profiles- the Moho depth is known to within a few km's. A relocation of earthquake source locations revealed that in India earthquakes occur throughout the whole lithosphere whereas in Tibet, earthquakes are restricted to the upper 10-15 km of the crust with few exceptions slightly above or below the Moho. The lack of substantial earthquake activity in the sub-Moho mantle lithosphere seems puzzling since (1D) strength envelop models for the continental lithosphere predict large differential stresses (and brittle failure) in these locations. A way out of this paradox is to assume that the rheology of the mantle lithosphere (i.e. the effective viscosity) is significantly smaller than usually assumed, either because of the effects of hydration, or because of increased Moho temperatures. As a consequence, the strength of the lithosphere resides in the crust and not in the upper mantle as previously assumed. This conclusion gets some support from spectral-based inverse models of the effective elastic thickness (using topography and gravity as input data), which is typically smaller than the seismogenic thickness. Even though this explanation might appear appealing at first, there are at least two major problems with it: (1) Estimations of the effective elastic thickness (EET) of the lithosphere are non-unique and model-dependent. Others, using a direct (non-spectral) modelling approach, find significantly larger values of the EET in the same locations (again using gravity & topography as constraints). (2) Long term geodynamic models indicate that if the mantle lithosphere would indeed be as weak as suggested, it would be very difficult to generate plate-tectonics like behavior: Subducting slabs behave more

  2. Continental Collision and the STEP-wise Evolution of Convergent Plate Boundaries: The Mediterranean Region

    NASA Astrophysics Data System (ADS)

    Wortel, M. J.; Govers, R.; Spakman, W.

    2008-12-01

    This contribution focusses on terminal stage subduction, often triggered by continent-continent or arc- continent collision. The landlocked basin setting of the Mediterranean region provides unique opportunities to study terminal stage subduction and its consequences. We use seismic tomography results on lithosphere and upper mantle structure as a source of information on plate boundary structure, and concentrate on the lithospheric scale aspects. Combining this structural information with process-oriented numerical modelling studies and regional observations, we present a 3D model for convergent plate boundary evolution after collision, in which slab detachment and the formation of tear or STEP (Subduction-Transform-Edge-Propagator; see R. Govers and M.J.R. Wortel, EPSL, 236, 505- 523, 2005) faults are key elements. A STEP fault laterally decouples subducting lithosphere from non- subducting lithosphere in a scissor type of fashion. It enhances the ability of a slab to retreat through the mantle flow around the edge of the subducted slab. In this way collision and back-arc extension may occur in close proximity. In our study area this specifically pertains to collision along the north African margin, STEP formation in easterly direction, CCW rotation of the southern Apennines slab and the opening of the Tyrrhenian Sea. Vertical tearing of subducted lithosphere may play an important role as well, but is probably not crucial. Similar processes are likely to have occurred in the eastern Mediterranean. On the basis of the good agreement between the Mediterranean-based model and the evolution of the Tonga-Fiji region we expect that the model may shed light on other complex convergent plate boundary regions, as well. In summary: Upon continental (or arc-continent) collision, along-trench variations in lithospheric properties of the subducting lithosphere may lead to disruption and segmentation of the subduction system. Following slab detachment along limited segments of

  3. Permo-Triassic and Paleoproterozoic metamorphism related to continental collision in Yangpyeong, South Korea

    NASA Astrophysics Data System (ADS)

    Oh, Chang Whan; Imayama, Takeshi; Lee, Seung Yeol; Yi, Sang-Bong; Yi, Keewook; Lee, Byung Choon

    2015-02-01

    Gneisses and migmatites exposed in the Yangpyeong area in the northern Gyeonggi Massif provide insight into the Paleoproterozoic and Triassic metamorphic events in South Korea. Garnet-biotite gneiss and sillimanite-garnet-biotite gneiss in the western part of the area reveal Paleoproterozoic metamorphism (1888-1871 Ma) at P-T conditions of 760-820 °C and 8-10 kbar and 710-750 °C and 5-7 kbar, respectively. These rocks were overprinted by low-P/T type metamorphism (590-650 °C, 3-4 kbar) during the Triassic (ca. 237 Ma). In contrast, a cordierite-rich migmatite near the post-collisional Triassic igneous complex in the eastern part of the area was strongly metamorphosed during the Triassic (ca. 235 Ma) at 750-790 °C and 7-8 kbar. The similar Triassic ages in the western and eastern areas suggest that low-P/T type metamorphism occurred as a second stage of regional metamorphism, which is characterized by the production of cordierite with an irregularly shaped garnet. The metamorphic grade of the Triassic metamorphism decreases spatially towards the west from granulite facies to amphibolite facies metamorphic conditions, and the Paleoproterozoic metamorphism is well preserved in the western part with low grade Triassic metamorphism. The new discovery of the Triassic metamorphic event in the Yangpyeong area, in addition to the previously reported Triassic post-collision igneous event, supports the idea that the continental collision belt between the North and South China blocks extends from the Hongseong area into the Odesan area through the Yangpyeong area in South Korea.

  4. Intraplate deformation due to continental collisions: A numerical study of deformation in a thin viscous sheet

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.; Morgan, R. C.

    1985-01-01

    A model of crustal deformation from continental collision that involves the penetration of a rigid punch into a deformable sheet is investigated. A linear viscous flow law is used to compute the magnitude and rate of change of crustal thickness, the velocity of mass points, strain rates and their principal axes, modes of deformation, areal changes, and stress. In general, a free lateral boundary reduces the magnitude of changes in crustal thickening by allowing material to more readily escape the advancing punch. The shearing that occurs diagonally in front of the punch terminates in compression or extension depending on whether the lateral boundary is fixed or free. When the ratio of the diameter of the punch to that of the sheet exceeds one-third, the deformation is insenstive to the choice of lateral boundary conditions. When the punch is rigid with sharply defined edges, deformation is concentrated near the punch corners. With non-rigid punches, shearing results in deformation being concentrated near the center of the punch. Variations with respect to linearity and nonlinearity of flow are discussed.

  5. Paleogene carbonate microfacies and sandstone provenance (Gamba area, South Tibet): Stratigraphic response to initial India-Asia continental collision

    NASA Astrophysics Data System (ADS)

    Li, Juan; Hu, Xiumian; Garzanti, Eduardo; An, Wei; Wang, Jiangang

    2015-05-01

    The Paleogene marine strata in the Gamba area of south Tibet comprise carbonates of the Zongpu Formation and siliciclastic rocks of the Enba and Zhaguo Formations, documenting the final stages of marine deposition in the Tethyan Himalaya. The ∼350-m-thick Zongpu Formation was dated as late Danian to Ypresian based on larger benthic foraminifers. Thirteen distinct microfacies identify three sedimentary environments. Mudstone, wackestone with Udoteacean algae, bioclastic-peloidal packstone, packstone with Rotaliids and green algae, floatstone with Alveolina and Orbitolites were deposited in restricted lagoonal environments. Bioclastic packstone and grainstone with Rotaliids were deposited in high-energy shoal environments. Floatstones with Nummulitids or Alveolinids were deposited in shallow open-marine environments. The Zongpu Formation was accumulated on a carbonate ramp. It documents two deepening-upward sequences separated by an unconformity corresponding to the Palaeocene/Eocene boundary and marked by a conglomerate with limestone clasts. The overlying Enba Formation comprises greenish grey calcareous shales intercalated with litho-quartzose sandstones in the upper part and capped by subaerial litho-quartzose red beds of the Zhaguo Formation. Petrographic analysis, detrital zircon geochronology and Hf isotopic data indicate that detritus in the Enba and Zhaguo Formations, deposited on the Indian passive margin, was derived from the Asian active margin in the north. These clastic units were thus deposited after the onset of the India-Asia continental collision in the early Himalayan foreland basin. Major lithological and paleoenvironmental changes occurred at three stratigraphic levels: the Jidula/Zongpu boundary (∼62 Ma), the Paleocene/Eocene boundary (∼56 Ma) and the Zongpu/Enba boundary (∼51 Ma). Our provenance study confirms that the India-Asia collision was already under way during the deposition of the Enba Member (i.e., by ∼51 Ma) and, along with

  6. Is the Ventersdorp rift system of southern Africa related to a continental collision between the Kaapvaal and Zimbabwe Cratons at 2.64 Ga AGO?

    NASA Technical Reports Server (NTRS)

    Burke, K.; Kidd, W. S. F.; Kusky, T.

    1985-01-01

    Rocks of the Ventersdorp Supergroup were deposited in a system of northeast trending grabens on the Kaapvaal Craton approximately 2.64 Ga ago contemporary with a continental collision between the Kaapvaal and Zimbabwe Cratons. It is suggested that it was this collision that initiated the Ventersdorp rifting. Individual grabens strike at high angles toward the continental collision zone now exposed in the Limpopo Province where late orogenic left-lateral strike-slip faulting and anatectic granites are recognized. The Ventersdorp rift province is related to extension in the Kaapvaal Craton associated with the collision, and some analogy is seen with such rifts as the Shansi and Baikal Systems associated with the current India-Asia continental collision.

  7. Integrating Spatial-Temporal Scales to Decipher Dynamics of Continental Subduction and Collision in the Alps

    NASA Astrophysics Data System (ADS)

    Engi, M.

    2014-12-01

    The European Alps display a complex record of subduction (Western Alps) and collision (Central Alps). Many of the tectonic units consist of mostly continental crust. Such polycyclic rocks are notoriously difficult to decipher, and countless efforts to analyze and quantify samples of Alpine basement have produced confusing data and controversial interpretations. As a result, the Alps have occasionally been portrayed as a pathological orogen… Recent progress in petrochronology yields robust in situ mineral ages that can be linked to physical conditions, i.e. quantitative PT-data for samples with a well established record of polyphase deformation. As the structural context is well known, integration of PTDt-data from mm-scale to km-tectonic units is possible. In the Western Alps, the analysis allows an assessment of dynamics in the continental subduction channel. Major kinematic differences emerge between adjacent slices of km-size; rates of the main orogenic processes are now known. The major diachronicity in the high-pressure imprint (e.g. Sesia: 84-63 Ma) reflects kinematic differences near the subduction interface, during subduction and (generally fast) exhumation - but with pressure cycling of at least one tectonic slice. The regional metamorphic imprint in the Central Alps is diachronous as well, but the causes are entirely different. High-pressure rocks are confined to two spatially separated units (a lithospheric mélange unit + an accretionary wedge); these are interleaved with several basement thrust sheets. The entire nappe stack experienced a medium pressure imprint. Petrochronology yields heating and cooling rates, and again the structural context is well enough established to understand the reasons of age differences at peak conditions (Tmax reached at 32-19 Ma in different parts of the belt). Overall, the reassessment of the orogenic timetable and processes helps to correct or reconcile many of the supposedly "abnormal" properties of the Alps. Unusual

  8. The tectonics of Cyprus Arc: a model of complex continental collision

    NASA Astrophysics Data System (ADS)

    Mart, Y.; Ryan, W.

    2003-04-01

    Cyprus Arc is an arcuate depression that wraps the southern reaches of Cyprus in the easternmost Mediterranean Sea. The tectonic regime that constrains Cyprus Arc is generally considered to be that of collision between northward moving Africa and southward moving Eurasia, and the Arc is the site where a Tethyan lithospheric toe off NE Africa is being subducted northward under the Anatolian sub-plate. Evidence to this process is the subduction of Eratosthenes Seamount, located 100 km south of Cyprus, the northern section of which is down-faulted as it subsides toward the Arc. Since Eratosthenes Seamount is rooted in continental lithosphere, and the Troodos ophiolite in southern Cyprus is an oceanic crust, the convergence of Africa and Anatolia along Cyprus Arc was considered a prime example of ongoing obduction. However, abundant GPS evidence shows that Anatolia is moving not southwards but westwards, and the rate of displacement exceeds 20 mm/yr, which is approximately 20 times faster than the rate of the northwards motion of Africa. Earthquakes reflect that composite dynamic model along Cyprus Arc, and compressional, extensional and strike-slip crustal motion co-occur along Cyprus Arc. Seismic reflection profiles show that the structural layout of the eastern segment of Cyprus Arc, from Hecataeus Plateau to Hatay region, is transtensional, emphasizing the prominence of the westwards motion of Anatolia. This composite pattern of the motion of the tectonic plates in the easternmost Mediterranean suggests that the slow northward motion of Africa leads indeed to subduction along Cyprus Arc, but this subduction is not counteracted, because Anatolia is moving much faster westwards. This dynamic setup of plate motion accounts for the composite pattern of earthquake distribution, and is compatible with large lateral displacements along strike of subduction zones and collisional fronts.

  9. P-T-t-z conditions in continental subduction settings , rheological and surface controls on the collision style

    NASA Astrophysics Data System (ADS)

    Burov, Evgueni

    2010-05-01

    We use thermo-dynamically coupled thermo-mechanical numerical models that account for brittle-elastic-ductile rheology, surface processes and continuous metamorphic phase changes to study continental subduction and the related P-T-t-z conditions in various subduction settings. The model traces P-T-t-z paths that can be interpreted in terms of collision/exhumation mechanism. The experiments suggest that continental subduction is a necessary context for UHP exhumation although it is short-lived in most cases (slow or fast convergence settings). Stable subduction occurs in case of strong lithospheres with competent mantle part (T_Moho<550°C), at high initial convergence rates (>1.5-5 cm/yr). Depending on lower-crustal rheology (strong or weak), either the entire (upper and lower) crust or only the lower crust can be involved in subduction. In case of weak metamorphic rheologies, phase changes leading to material softening significantly improve chances for stable subduction. Exhumation of UHP-HP rocks to the surface is favoured if the crustal rheological profile has internal ductile decolement levels (between the upper and lower or intermediate crust and the lower crust and mantle lithosphere). Pure shear collision is dominant when T_Moho>550°C or convergence rates are lower than 1.5-3 cm/yr (subduction number, S > 0.5). The maximal amount of subduction is achieved for surface erosion rates such that tectonic uplift rates are fine-balanced by denudation rates. In case of fast collision scenario (convergence > 5 cm/y, stiff lower plate), the optimal balance is achieved for k ~3000-4000 m2/yr. In case of fast convergence settings, continental subduction may continue for tens of Myr allowing for subduction of 600 - 800 km of continental "slab", and both surface and deep mantle evolution are strongly affected by surface processes. We suggest that most orogenic belts could have started their formation from continental subduction, yet, in case of slow convergence (<2-3 cm

  10. Subducted upper and lower continental crust contributes to magmatism in the collision sector of the Sunda-Banda arc, Indonesia

    NASA Astrophysics Data System (ADS)

    Elburg, M. A.; van Bergen, M. J.; Foden, J. D.

    2004-01-01

    Pb isotopes in igneous rocks from the Banda-Sunda arc show extreme along-arc variations, which correspond to major lithologic changes in crustal components entering the subduction system. An increase in 206Pb/204Pb ratios toward the zone of collision with the Australian continent reflects input of subducted upper-crustal material; maximum values coincide with anomalously radiogenic 3He/4He ratios that have been earlier attributed to the involvement of the continental margin. The collision zone is further characterized by 208Pb/204Pb ratios that are higher for a given 207Pb/204Pb value than observed in the noncollisional sectors, and in the central part of the collision zone, the 206Pb/204Pb ratios are lower than the most radiogenic values in the adjacent areas. We propose that these Pb isotope signatures reflect input of subducted lower crust, mobilized as a result of slab-window formation during arc-continent collision. Variations in Pb isotopes in the collision zone are solely determined by variations in the nature and proportions of different subducted components. The Pb isotope arrays in the noncollision area may be dominated by slab components as well and could reflect mixing between subducted oceanic crust and entrained sediments, rather than between subarc mantle and subducted sediments. Our new interpretation of the Indonesian Pb isotope data does not call for involvement of ocean-island basalt (OIB) type mantle or Australian subcontinental lithospheric mantle, as has been suggested previously.

  11. Active Collision Avoidance for Planetary Landers

    NASA Technical Reports Server (NTRS)

    Rickman, Doug; Hannan, Mike; Srinivasan, Karthik

    2014-01-01

    Present day robotic missions to other planets require precise, a priori knowledge of the terrain to pre-determine a landing spot that is safe. Landing sites can be miles from the mission objective, or, mission objectives may be tailored to suit landing sites. Future robotic exploration missions should be capable of autonomously identifying a safe landing target within a specified target area selected by mission requirements. Such autonomous landing sites must (1) 'see' the surface, (2) identify a target, and (3) land the vehicle. Recent advances in radar technology have resulted in small, lightweight, low power radars that are used for collision avoidance and cruise control systems in automobiles. Such radar systems can be adapted for use as active hazard avoidance systems for planetary landers. The focus of this CIF proposal is to leverage earlier work on collision avoidance systems for MSFC's Mighty Eagle lander and evaluate the use of automotive radar systems for collision avoidance in planetary landers.

  12. A lithospheric seismic profile across northern Taiwan, from arc-continental collision to extension

    NASA Astrophysics Data System (ADS)

    Van Avendonk, H. J.; McIntosh, K. D.; Lavier, L. L.; Wu, F. T.; Okaya, D. A.; Kuochen, H.

    2012-12-01

    Taiwan is one of a few locations where a subduction zone is transitioning to arc-continent collision. The north-south trending Luzon arc, which is built on the Philippine Sea Plate, has been overriding the Eurasian margin here since the Late Miocene. Shortening of the Eurasian margin lead to the formation of the Taiwan mountain belt. The plate boundary is quite complicated in northeastern Taiwan, because the Philippine Sea Plate also subducts beneath the Eurasian plate along the east-west trending Ryukyu trench. Since the Pleistocene, backarc extension behind the Ryukyu arc in the Okinawa Trough has propagated into the Ilan Plain, a region that previously experienced shortening during collision with the Luzon arc. The deep structure of northern Taiwan can therefore give us insight in the evolution of the orogen from compression to post-collisional collapse. During the 2008 and 2009 field seasons of the TAIGER project we acquired active-source and earthquake seismic data in Taiwan and surrounding oceans to better understand the different stages of arc-continent collision. On the island of Taiwan, explosion seismic, onshore-offshore and marine seismic data constrain the crustal structure along three large east-west transects across the plate boundary. In the north, TAIGER transect T6 spans a distance of 360 km from the Taiwan Strait eastward across the Hsuehshan Range and the Central Range, and onto the Ryukyu forearc. Marine seismic data were shot with the R/V Marcus Langseth in the Taiwan Strait and east of Taiwan. Twelve ocean-bottom seismometers from National Taiwan Ocean University (NTOU) recorded seismic refractions offshore, and land-seismic stations from IRIS/PASSCAL recorded airgun shots from the Langseth and 4 large land seismic explosions. These different types of active-source data together provide good spatial coverage for imaging seismic velocity structure across the orogen and the plate boundary. The seismic refraction data include crustal turning

  13. Magnetism at Depth: A view from an ancient continental collision zone

    NASA Astrophysics Data System (ADS)

    McEnroe, S. A.; Purucker, M. E.; Robinson, P.

    2015-12-01

    The contribution to lithospheric magnetization from deep crustal rocks remains enigmatic. Based on models from satellite studies, the magnetic signature of the crust is best fitted using a susceptibility value of ~0.04 SI. Current models use crustal thicknesses from seismic and thermal studies, and then attempt to fit satellite magnetic data using a magnetic response in the direction of the present day field. This susceptibility is significantly higher than is found in many continental rocks. It is an open question whether there are more magnetic rocks at depth, if parts of the mantle could contribute, or if assumptions in the model are incomplete. The magnetic response of deep crustal rocks is strongly controlled by the amount and oxidation state of magnetic minerals, thermal structure of the crust, whether fluids were available during metamorphism, and at what Ts and Ps reactions occurred. Subduction zones have been proposed as areas of enhanced magnetic signal due to production of magnetite, however high-grade metamorphism to eclogite facies may destroy magnetic minerals as Fe is absorbed into garnet. Contributions from mantle rocks would depend on the compositions of olivine and pyroxene, fluid availability, and PT regimes capable of producing magnetite. 1450 samples from mafic and ultramafic bodies in the Western Gneiss Region (WGR), Norway, >300 from the Leka Ophiolite, and >350 of ultramafic rocks from the Seiland Igneous Province were studied in the Scandian collision zone. They show strong variations in petrophysical properties, oxide mineralogy and assemblages. Four groups of WGR samples, represent different metamorphic conditions and crustal depths: 1) Garnet-corona gabbros considered to have reached 600-750oC and 1-1.5 Gpa, equivalent to depths up to 60 km; 2) Normal eclogite-facies rocks that reached 700-750oC and 1.5 -2.5 Gpa, equivalent to depths of 60-90 km; 3) Ultrahigh-pressure eclogite-facies rocks that reached 750-850oC and 2.5-4 Gpa, equivalent

  14. Record of Cenozoic sedimentation from the Amanos Mountains, Southern Turkey: Implications for the inception and evolution of the Arabia-Eurasia continental collision

    NASA Astrophysics Data System (ADS)

    Boulton, Sarah J.

    2009-04-01

    The sedimentary succession of the southern Amanos Mountains, bordering the eastern margin of the Karasu Rift in south central Turkey, provides a record of environmental change from the Eocene (Lutetian) to the Upper Miocene (Tortonian) that charts the final evolution of the northern margin of the Arabian plate prior to and during continental collision. Eocene shallow-marine carbonates (Hacıdağı Formation) are interpreted as the youngest unit of the Arabian passive margin succession deposited on a northwards facing carbonate ramp. Subsequent deformation and uplift took place during the Oligocene represented by folding of the Eocene and older strata. This is interpreted to be the result of initial continental collision between Arabia and Eurasia. Unconformably overlying the Eocene limestone are Lower Miocene conglomerates, sandstones and palaeosols up to 150 m thick (Kıcı Formation). These were deposited in a range of marginal marine settings consisting of alluvial fan/fan delta facies, flood plain as well as basinal facies. Subsequently, during the Middle Miocene, local patch reefs developed in restricted areas (Kepez Formation) followed by Upper Miocene sediments (Gökdere Formation) composed of relatively deep water hemipelagic marl, with clastic interbeds, which represent a transgression during this period. The Upper Miocene becomes sandier upwards, this records the regression from the relatively deep water facies to coastal sediments. Water depth gradually became shallower until during Pliocene time the area became continental in nature. By the Quaternary rifting had resulted in the development of the Karasu Rift with active alluvial fans along the margins and braided rivers depositing coarse conglomerates in the axial zone. These conglomerates are interbedded with basaltic lava flows that resulted from the region extension across the area. This research shows that initial continental collision occurred in this area after the Lutetian (40.4 Ma) and before

  15. 76 FR 58273 - Agency Information Collection Activities; Proposed Collection; Comment Request; Outer Continental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-20

    ... Collection Activities; Proposed Collection; Comment Request; Outer Continental Shelf Air Regulations; EPA ICR... all outer continental shelf (OCS) sources except those located in the Gulf of Mexico west of 87.5... boundary extends three leagues (about nine miles) from the coastline. Title: Outer Continental Shelf...

  16. Two-dimensional numerical modeling of tectonic and metamorphic histories at active continental margins

    NASA Astrophysics Data System (ADS)

    Gerya, Taras; Stöckhert, Bernhard

    2006-04-01

    The evolution of an active continental margin is simulated in two dimensions, using a finite difference thermomechanical code with half-staggered grid and marker-in-cell technique. The effect of mechanical properties, changing as a function of P and T, assigned to different crustal layers and mantle materials in the simple starting structure is discussed for a set of numerical models. For each model, representative P T paths are displayed for selected markers. Both the intensity of subduction erosion and the size of the frontal accretionary wedge are strongly dependent on the rheology chosen for the overriding continental crust. Tectonically eroded upper and lower continental crust is carried down to form a broad orogenic wedge, intermingling with detached oceanic crust and sediments from the subducted plate and hydrated mantle material from the overriding plate. A small portion of the continental crust and trench sediments is carried further down into a narrow subduction channel, intermingling with oceanic crust and hydrated mantle material, and to some extent extruded to the rear of the orogenic wedge underplating the overriding continental crust. The exhumation rates for (ultra)high pressure rocks can exceed subduction and burial rates by a factor of 1.5 3, when forced return flow in the hanging wall portion of the self-organizing subduction channel is focused. The simulations suggest that a minimum rate of subduction is required for the formation of a subduction channel, because buoyancy forces may outweigh drag forces for slow subduction. For a weak upper continental crust, simulated by a high pore pressure coefficient in the brittle regime, the orogenic wedge and megascale melange reach a mid- to upper-crustal position within 10 20 Myr (after 400 600 km of subduction). For a strong upper crust, a continental lid persists over the entire time span covered by the simulation. The structural pattern is similar in all cases, with four zones from trench toward arc

  17. Continental collision, slab detachment and K-rich magmatism: central-southern Italy as a type example

    NASA Astrophysics Data System (ADS)

    Wortel, M. J. R.; van Bergen, M. J.; van de Zedde, D. M. A.; Spakman, W.

    2003-04-01

    implicitly incorporating enormous amounts of information acquired by geophysical and geological studies independent of petrological data. As such, our study may serve as a calibration of the relation between subduction zone evolution and post-collisional, K-rich volcanism and may shed light upon post-collisional magmatism in older regions of continental collision and suturing, among which the Tethyan-Himalayan suture zone is the most prominent one.

  18. Activating main belt comets by collisions

    NASA Astrophysics Data System (ADS)

    Maindl, T. I.; Haghighipour, N.; Schäfer, C.; Speith, R.

    2016-02-01

    Since their identification as a new class of bodies by Hsieh and Jewitt in 2006 active asteroids (or Main Belt Comets, MBCs) have attracted a great deal of interest. Given that sublimation of volatile material (presumably water-ice) drives MBC activity, these bodies are probable candidates for delivering a significant amount of Earth's water. Dynamical studies suggest in-situ formation of MBCs as the remnants of the break-up of large icy asteroids. Also, collisions between MBCs and small objects might have exposed sub-surface water-ice triggering the cometary activity of these bodies. In order to advance the effort of understanding the nature of MBC activation, we have investigated these collision processes by simulating the impacts in detail using a smooth particle hydrodynamics (SPH) approach that includes material strength and fracture models. Our simulations cover a range of impact velocities (between 0.5 km/s and 5.3 km/s) and angles, allowing m-sized impactors to erode enough of an MBC's surface to expose volatiles and trigger its activation. We also varied the material strength of the active asteroid's surface to study its influence on crater depths and shapes. As expected, depending on the impact energy, impact angle, and MBC's material strength we observe different crater depths. Across all scenarios however, our results show that the crater depths do not exceed a few meters. This implies that if the activity of MBCs is due to sublimating water-ice, ice has to exist in no deeper than a few meters from the surface.

  19. Triassic mafic and intermediate magmatism associated with continental collision between the North and South China Cratons in the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Yi, Sang-Bong; Oh, Chang Whan; Lee, Seung-Yeol; Choi, Seon-Gyu; Kim, Taesung; Yi, Keewook

    2016-03-01

    Triassic coeval mafic and intermediate magmatism occurred in the area suggested to be the southern margin of the North China Craton (NCC) in the Gyeonggi Massif (GM) of the Korean Peninsula. This study investigates aspects of the mafic and intermediate magmatism using SHRIMP zircon ages and whole-rock chemical and isotopic Sr-Nd data. The mafic and intermediate rocks intruded into a basement paragneiss in three areas (Yangpyeong, Odesan and Yangyang) within the GM at ca. 230 Ma. The paragneiss was metamorphosed in both the Paleoproterozoic and Triassic. Gabbros (hornblende gabbro and pyroxene-mica gabbro) from the study areas exhibit strong light REE (LREE) enrichment relative to chondrite (LaN/YbN = 11.1-30.6) and a high LILE/HFSE pattern, Ta-Nb-P-Ti troughs and positive Ba-K-Pb-Sr spikes on the N-MORB-normalized multi-element variation diagram. These features are typical characteristics of arc-related gabbros. The gabbros also show strongly enriched initial isotopic compositions (87Sr/86Sr(i) = 0.7100-0.7137; εNd(t) = - 13.1 to - 19.7). The coeval intermediate intrusive rocks also exhibit whole-rock chemical and isotopic features (87Sr/86Sr(i) = 0.7099-0.7143; εNd(t) = - 10.8 to - 18.6) similar to those of the gabbros. The mafic and intermediate intrusive rocks plot in the within-plate and/or post-collisional fields on tectonic discrimination diagrams. These data indicate that the mafic and intermediate magmatism in the study areas occurred during the Triassic post-collisional relaxation period via partial melting of sub-continental lithospheric mantle (SCLM) that was enriched in a subduction environment prior to (or during) the Permo-Triassic continental collision between the NCC and the South China Craton (SCC). The highly enriched mantle signatures revealed by the gabbros from the study areas are matched to the enriched features identified in Cretaceous mafic igneous rocks (ca. 130 Ma) on the southern margin of the NCC. Thus, this study suggests that the

  20. Investigating Continental Margins: An Activity to Help Students Better Understand the Continental Margins of North America

    ERIC Educational Resources Information Center

    Poli, Maria-Serena; Capodivacca, Marco

    2011-01-01

    Continental margins are an important part of the ocean floor. They separate the land above sea level from the deep ocean basins below and occupy about 11% of Earth's surface. They are also economically important, as they harbor both mineral resources and some of the most valuable fisheries in the world. In this article students investigate North…

  1. Record of Cenozoic sedimentation from the Amanos Mountains, Southern Turkey: implications for the inception and evolution of the Arabia-Eurasia continental collision

    NASA Astrophysics Data System (ADS)

    Boulton, S. J.

    2009-04-01

    The sedimentary succession of the southern Amanos Mountains, bordering the eastern margin of the Karasu Rift in south central Turkey, provides a record of environmental change from the Eocene (Lutetian) to the Upper Miocene (Tortonian) charting the final evolution of the northern Arabian plate margin prior to, and during, continental collision. Eocene shallow-marine carbonates (Hacıdağı Formation) are interpreted as the youngest unit of the Arabian passive margin succession deposited on a northwards facing carbonate ramp. Subsequent deformation and uplift took place during the Oligocene represented by folding of the Eocene and older strata. Unconformably overlying the Eocene limestone are Lower Miocene conglomerates, sandstones and palaeosols up to 150 m thick (Kıcı Formation). These were deposited in a range of marginal marine settings consisting of alluvial fan, flood plain and shallow marine/lower shoreface environments interpreted as a ‘fan-delta' prograding from the uplifted proto-Amanos into a marine embayment. Subsequently, during the Middle Miocene, local patch reefs developed in restricted areas (Kepez Formation) followed by Upper Miocene sediments (Gökdere Formation) composed of deeper water marine marl, with clastic interbeds, which represents a transgression during this period. The Upper Miocene becomes sandier upwards, this records the regression from the relatively deep water facies to coastal sediments. Water depth gradually became shallower until during the Pliocene the area became continental. By the Quaternary rifting had resulted in the development of the Karasu Rift with active alluvial fans along the margins and braided rivers depositing coarse conglomerates in the axial zone. These conglomerates are interbedded with basaltic lava flows that resulted from the regional extension across the area. This research shows that initial continental collision occurred in this area after the Lutetian (40.4 Ma) and before the Aquitanian (23.03 Ma

  2. Continental break-up and collision in the Neoproterozoic and Palaeozoic — A tale of Baltica and Laurentia

    NASA Astrophysics Data System (ADS)

    Torsvik, T. H.; Smethurst, M. A.; Meert, J. G.; Van der Voo, R.; McKerrow, W. S.; Brasier, M. D.; Sturt, B. A.; Walderhaug, H. J.

    1996-06-01

    a short and rapid excursion to lower latitudes in the Late Vendian, remained mostly in intermediate to high southerly latitudes and closer to the Gondwana margin until Early Ordovician times. In Early Ordovician times, Arenig-Llanvirn platform trilobites show a broad distinction between the continents of Laurentia/Siberia/North China Block (Bathyurid), Baltica (Ptychopygine/ Megalaspid) and the areas of NW Gondwana/Avalonia/Armorica (Calymenacean-Dalmanitacean). During the Ordovician, Baltica rotated and moved northward, approaching close enough to Laurentia by the late Caradoc for trilobite and brachiopod spat to cross the intervening Iapetus Ocean. Docking appears to have been irregular both in time and manner: the collision between Scotland/Greenland and western Norway resulted in the early Scandian Orogeny in the Silurian (c. 425 Ma), but further south, there is evidence of late Silurian impingement with subduction of Avalonian continental crust (in England and Ireland) below the eastern edge of Laurentia until the Emsian. In the northern Appalachians the main time of collision appears to have been during the Emsian/Eifellian Acadian Orogeny. Recent analyses invalidates the traditional concept of a sustained orthogonal relationship between Baltica and Laurentia across a single Iapetus Ocean throughout the Caledonide evolution. The active margin of Baltica (Scandinavian Caledonides) faced Siberia during the Late Cambrian and Early Ordovician with oceanic separation between these landmasses in the order of 1200-1500 km. This may explain the local occureences of Siberia-Laurentian type Bathyarid tribobite faunas in Central Norwegian Caledonian nappes, earlier interpreted as Laurentia-Baltica trilobite mixing. Subsequent counterclockwise rotation of Baltica transferred the Caledonian margin in the direction of Laurentia by Silurian times, when the two continents once again started to collide to form Euramerica. This rotation, along with the strongly asymmetric

  3. Adakitic (tonalitic-trondhjemitic) magmas resulting from eclogite decompression and dehydration melting during exhumation in response to continental collision

    NASA Astrophysics Data System (ADS)

    Song, Shuguang; Niu, Yaoling; Su, Li; Wei, Chunjing; Zhang, Lifei

    2014-04-01

    Modern adakite or adakitic rocks are thought to result from partial melting of younger and thus warmer subducting ocean crust in subduction zones, with the melt interacting with or without mantle wedge peridotite during ascent, or from melting of thickened mafic lower crust. Here we show that adakitic (tonalitic-trondhjemitic) melts can also be produced by eclogite decompression during exhumation of subducted and metamorphosed oceanic/continental crust in response to continental collision, as exemplified by the adakitic rocks genetically associated with the early Paleozoic North Qaidam ultra-high pressure metamorphic (UHPM) belt on the northern margin of the Greater Tibetan Plateau. We present field evidence for partial melting of eclogite and its products, including adakitic melt, volumetrically significant plutons evolved from the melt, cumulate rocks precipitated from the melt, and associated granulitic residues. This “adakitic assemblage” records a clear progression from eclogite decompression and heating to partial melting, to melt fractionation and ascent/percolation in response to exhumation of the UHPM package. The garnetite and garnet-rich layers in the adakitic assemblage are of cumulate origin from the adakitic melt at high pressure, and accommodate much of the Nb-Ta-Ti. Zircon SHRIMP U-Pb dating shows that partial melting of the eclogite took place at ∼435-410 Ma, which postdates the seafloor subduction (>440 Ma) and temporally overlaps the UHPM (∼440-425 Ma). While the geological context and the timing of adakite melt formation we observe differ from the prevailing models, our observations and documentations demonstrate that eclogite melting during UHPM exhumation may be important in contributing to crustal growth.

  4. The onset of India-Asia continental collision: Early, steep subduction required by the timing of UHP metamorphism in the western Himalaya [rapid communication

    NASA Astrophysics Data System (ADS)

    Leech, Mary L.; Singh, S.; Jain, A. K.; Klemperer, Simon L.; Manickavasagam, R. M.

    2005-05-01

    Ultrahigh-pressure (UHP) rocks in the NW Himalaya are some of the youngest on Earth, and allow testing of critical questions of UHP formation and exhumation and the timing of the India-Asia collision. Initial collision of India with Asia is widely cited as being at 55 ± 1 Ma based on a paleomagnetically determined slowdown of India's plate velocity, and as being at ca. 51 Ma based on the termination of marine carbonate deposition. Even relatively small changes in this collision age force large changes in tectonic reconstructions because of the rapid India-Asia convergence rate of 134 mm/a at the time of collision. New U-Pb SHRIMP dating of zircon shows that Indian rocks of the Tso Morari Complex reached UHP depths at 53.3 ± 0.7 Ma. Given the high rate of Indian subduction, this dating implies that Indian continental crust arrived at the Asian trench no later than 57 ± 1 Ma, providing a metamorphic age for comparison with previous paleomagnetic and stratigraphic estimates. India's collision with Asia may be compared to modern processes in the Timor region in which initiation of collision precedes both the slowing of the convergence rate and the termination of marine carbonate deposition. The Indian UHP rocks must have traveled rapidly along a short, hence steep, path into the mantle. Early continental subduction was at a steep angle, probably vertical, comparable to modern continental subduction in the Hindu Kush, despite evidence for modern-day low-angle subduction of India beneath Tibet. Oceanic slab break-off likely coincided with exhumation of UHP terranes in the western Himalaya and led to the initiation of low-angle subduction and leucogranite generation.

  5. 78 FR 27427 - Outer Continental Shelf (OCS) Geological and Geophysical Exploration Activities in the Gulf of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-10

    ... Bureau of Ocean Energy Management Outer Continental Shelf (OCS) Geological and Geophysical Exploration... ] Geological and Geophysical Exploration for Mineral Resources on the Gulf of Mexico Outer Continental Shelf... activities in GOM waters. It will also provide information for future decisions regarding Outer...

  6. 78 FR 33859 - Outer Continental Shelf (OCS) Geological and Geophysical Exploration Activities in the Gulf of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... Bureau of Ocean Energy Management Outer Continental Shelf (OCS) Geological and Geophysical Exploration.... SUMMARY: On May 10, 2013, BOEM published a document in the Federal Register (78 FR 27427) entitled ``Outer Continental Shelf Geological and Geophysical Exploration Activities in the Gulf of Mexico.'' This...

  7. Arc-continent collision and the formation of continental crust: A new geochemical and isotopic record from the Ordovician Tyrone Igneous Complex, Ireland

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Amato, Jeffrey M.; Blusztajn, Jerzy; Schouten, Hans

    2009-01-01

    Collisions between oceanic island-arc terranes and passive continental margins are thought to have been important in the formation of continental crust throughout much of Earth's history. Magmatic evolution during this stage of the plate-tectonic cycle is evident in several areas of the Ordovician Grampian-Taconic orogen, as we demonstrate in the first detailed geochemical study of the Tyrone Igneous Complex, Ireland. New U-Pb zircon dating yields ages of 493 2 Ma from a primitive mafic intrusion, indicating intra-oceanic subduction in Tremadoc time, and 475 10 Ma from a light rare earth element (LREE)-enriched tonalite intrusion that incorporated Laurentian continental material by early Arenig time (Early Ordovician, Stage 2) during arc-continent collision. Notably, LREE enrichment in volcanism and silicic intrusions of the Tyrone Igneous Complex exceeds that of average Dalradian (Laurentian) continental material that would have been thrust under the colliding forearc and potentially recycled into arc magmatism. This implies that crystal fractionation, in addition to magmatic mixing and assimilation, was important to the formation of new crust in the Grampian-Taconic orogeny. Because similar super-enrichment of orogenic melts occurred elsewhere in the Caledonides in the British Isles and Newfoundland, the addition of new, highly enriched melt to this accreted arc terrane was apparently widespread spatially and temporally. Such super-enrichment of magmatism, especially if accompanied by loss of corresponding lower crustal residues, supports the theory that arc-continent collision plays an important role in altering bulk crustal composition toward typical values for ancient continental crust. ?? 2009 Geological Society of London.

  8. Finite strain calculations of continental deformation. I - Method and general results for convergent zones. II - Comparison with the India-Asia collision zone

    NASA Technical Reports Server (NTRS)

    Houseman, G.; England, P.

    1986-01-01

    The present investigation has the objective to perform numerical experiments on a rheologically simple continuum model for the continental lithosphere. It is attempted to obtain a better understanding of the dynamics of continental deformation. Calculations are presented of crustal thickness distributions, stress, strain, strain rate fields, latitudinal displacements, and finite rotations, taking into account as basis a model for continental collision which treats the litoshphere as a thin viscous layer subject to indenting boundary conditions. The results of this paper support the conclusions of England and McKenzie (1982) regarding the role of gravity in governing the deformation of a thin viscous layer subject to indenting boundary conditions. The results of the experiments are compared with observations of topography, stress and strain rate fields, and palaeomagnetic latitudinal displacements in Asia.

  9. Receiver function imaging of crustal suture, steep subduction, and mantle wedge in the eastern India-Tibet continental collision zone

    NASA Astrophysics Data System (ADS)

    Shi, Danian; Wu, Zhenhan; Klemperer, Simon L.; Zhao, Wenjin; Xue, Guangqi; Su, Heping

    2015-03-01

    To understand the along-strike variation of crustal deformation and tectonic processes in the India-Tibet continental collision zone, we deployed a linear array of broadband seismic stations along 92° E to image lithospheric structure. Our receiver-function cross-section reveals a prominent negative converter dipping ∼20° north from ∼10-55 km depth below sea-level, almost through the whole crust, beneath the southern Lhasa terrane. We interpret it to be a manifestation of the Yarlung-Zangbo suture zone (YZS) separating the continental crust of the Indian and Eurasian plates. This implies the hypothesized channel-flows of Indian middle crust extruding southwards from Tibet are limited at this longitude to the southernmost portion of the Lhasa terrane. A positive converter, consistent with previous suggestions of eclogite formation, is seen about 10-15 km above the Moho and continuing 50 km north of the 20°-dipping YZS converter. We image this positive converter continuously from ∼60 km south of the surface trace of the YZS to the vicinity of the Jiali fault, supporting the interpretation of sub-horizontal underplating of Tibetan crust by Indian crust to ∼31° N at 85° E on the Hi-CLIMB transect. However, we also show a negative mantle converter sub-parallel to the crustal YZS converter, from the northern limit of the underplating Indian lower crust to at least 140 km depth, that we interpret as the base of Tibetan lithosphere overlying an asthenospheric mantle wedge. Based on the lithospheric structure observed in this and other studies, we infer that Indian mantle lithosphere currently detaches from Indian lower crust at the "mantle suture" that is nearly 50 km south of the surface trace of the YZS at 92° E, south of the mantle suture suggested by INDEPTH transect beneath the surface trace of the YZS at ∼90° E, and far south of the mantle suture suggested to be at the 31° N northern limit of underthrusting Indian lower crust suggested by Hi

  10. Detection of partial melt in continental collision zones using different magnetotelluric tensor relationships: Results from synthetic models and real data

    NASA Astrophysics Data System (ADS)

    LLovet, Joan Campanya i.; Ledo, Juanjo; Jones, Alan G.; Queralt, Pilar; Marcuello, Alex; Liesa, Montserrat; Antón Muñoz, Josep

    2014-05-01

    Three magnetotelluric (MT) tensor relationships - the single-station MT impedance tensor (Z), the single-station vertical geomagnetic transfer function (GTF) and the multiple-station horizontal geomagnetic transfer function (HGTF) - were investigated for their effectiveness in detecting the presence of partial melt in continental collision zones. Realistic synthetic models, based on prior field studies, were used to characterize the sensitivity of each tensor relationship constraining the presence of partial melt at lower-crustal and upper-mantle depths. From the MT response of the synthetic models, each type of data was inverted separately and jointly with the others, thus determining the properties and advantages of each when modeling the subsurface. Non-linear sensitivity tests were carried out to determine the resolution that can be expected in constraining electrical resistivity anomalies associated with the presence of partial melt. Results obtained show which configuration of the HGTF is more sensitive to partial melt. The analysis of partial melt sensitivity was also performed using real data from a MT survey carried out in the Pyrenees. The data comprise a total of 82 broadband MT sites and 29 long period MT sites distributed along four profiles across the Pyrenean mountain range between the Atlantic Ocean and the Mediterranean Sea. Using the results from the synthetic models, real MT data in the Eastern Pyrenees were used to constrain if the partial melting area associated with the Iberian subducted lower crust observed below the Western, the West-central and the Central Pyrenees continues to the East. A non-linear sensitivity test was undertaken to determine the boundary to the east of this geoelectrical anomaly associated with partial melt.

  11. Research activities on submarine landslides in gentle continental slope

    NASA Astrophysics Data System (ADS)

    Morita, S.; Goto, S.; Miyata, Y.; Nakamura, Y.; Kitahara, Y.; Yamada, Y.

    2013-12-01

    In the north Sanrikuoki Basin off Shimokita Peninsula, NE Japan, a great number of buried large slump deposits have been identified in the Pliocene and younger formations. The basin has formed in a very gentle continental slope of less than one degree in gradient and is composed of well-stratified formations which basically parallel to the present seafloor. This indicates that the slumping have also occurred in such very gentle slope angle. The slump units and their slip surfaces have very simple and clear characteristics, such as layer-parallel slip on the gentle slope, regularly imbricated internal structure, block-supported with little matrix structure, widespread dewatering structure, and low-amplitude slip surface layer. We recognize that the large slump deposits group of layer-parallel slip in this area is an appropriate target to determine 'mechanism of submarine landslides', that is one of the subjects on the new IODP science plan for 2013 and beyond. So, we started some research activities to examine the feasibility of the future scientific drilling. The slump deposits were recognized basically by 3D seismic analysis. Further detailed seismic analysis using 2D seismic data in wider area of the basin is being performed for better understanding of geologic structure of the sedimentary basin and the slump deposits. This will be good source to extract suitable locations for drill sites. Typical seismic features and some other previous studies imply that the formation fluid in this study area is strongly related to natural gas, of which condition is strongly affected by temperature. So, detailed heat flow measurements was performed in the study area in 2013. For that purpose, a long-term water temperature monitoring system was deployed on the seafloor in October, 2012. The collected water temperature variation is applied to precise correction of heat flow values. Vitrinite reflectance analysis is also being carried out using sediments samples recovered by IODP

  12. Nurture Versus Nature: Accounting for the Differences Between the Taiwan and Timor active arc-continent collisions

    NASA Astrophysics Data System (ADS)

    Harris, R. A.

    2011-12-01

    The active Banda arc/continent collision of the Timor region provides many important contrasts to what is observed in Taiwan, which is mostly a function of differences in the nature of the subducting plate. One of the most important differences is the thermal state of the respective continental margins: 30 Ma China passive margin versus 160 Ma NW Australian continental margin. The subduction of the cold and strong NW Australian passive margin beneath the Banda trench provides many new constraints for resolving longstanding issues about the formative stages of collision and accretion of continental crust. Some of these issues include evidence for slab rollback and subduction erosion, deep continental subduction, emplacement or demise of forearc basement, relative amounts of uplift from crustal vs. lithospheric processes, influence of inherited structure, partitioning of strain away from the thrust front, extent of mélange development, metamorphic conditions and exhumation mechanisms, continental contamination and accretion of volcanic arcs, does the slab tear, and does subduction polarity reverse? Most of these issues link to the profound control of lower plate crustal heterogeneity, thermal state and inherited structure. The thermomechanical characteristics of subducting an old continental margin allow for extensive underthrusting of lower plate cover units beneath the forearc and emplacement and uplift of extensive nappes of forearc basement. It also promotes subduction of continental crust to deep enough levels to experience high pressure metamorphism (not found in Taiwan) and extensive contamination of the volcanic arc. Seismic tomography confirms subduction of continental lithosphere beneath the Banda Arc to at least 400 km with no evidence for slab tear. Slab rollback during this process results in massive subduction erosion and extension of the upper plate. Other differences in the nature of the subducting plates in Taiwan in Timor are differences in the

  13. New geoelectrical characterisation of a continental collision zone in the West-Central Pyrenees: Constraints from long period and broadband magnetotellurics

    NASA Astrophysics Data System (ADS)

    Campanyà, Joan; Ledo, Juanjo; Queralt, Pilar; Marcuello, Alex; Liesa, Montserrat; Muñoz, Josep A.

    2012-06-01

    Continental collision dominates the development of a large number of mountain ranges on Earth. Although the geological evolution of these regions is highly studied, lithospheric-scale physical processes are less well characterised and their interpretations frequently differ. A new magnetotelluric profile crossing the West-Central Pyrenees with broadband and long period magnetotelluric data constrains the geoelectrical features of this continental collision zone confining the geological and physical processes that take place at a lithospheric scale. Three geoelectrical structures associated with partial melting and its melt migration are imaged for the first time in the West-Central Pyrenees suggesting an Iberian subducted lower crust reaching the depth of 70 km. This result, supported by an analysis of the thermal evolution of the Iberian subducted lower crust, reinforces the hypothesis of partial melting in this region. From the long period magnetotelluric data, the asthenosphere has been imaged as a geoelectrical structure with electrical resistivity values between 20 Ω m and 70 Ω m. The lithosphere-asthenosphere boundary close to the collision zone has been constrained between 90 km and 110 km depth below the Iberian plate and between 120 km and 160 km depth below the transition zone between plates and the European plate, in agreement with the previous geophysical data. Additionally, other geoelectrical anomalies imaged have been associated with an unexpected major Variscan boundary located below the Ebro basin, Silurian sediments and free fluids in the Gavarnie thrust, and with a thick sequence of Jurassic and Early Cretaceous sediments situated below the North Pyrenean Thrust Sheet.

  14. Alkaline series related to Early-Middle Miocene intra-continental rifting in a collision zone: An example from Polatlı, Central Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

    Temel, Abidin; Yürür, Tekin; Alıcı, Pınar; Varol, Elif; Gourgaud, Alain; Bellon, Hervé; Demirbağ, Hünkar

    2010-06-01

    A large volcanic area (˜7600 km 2), the Galatean Volcanic Province (GVP), developed in northwest Central Anatolia during the Miocene along the Neo-Tethys Ocean suture zone possibly by post-collisional processes. The GVP mainly comprises 20-14 My old acid to intermediate volcanites with a geochemical signature indicating a mantle source modified by earlier (Late Cretaceous) subduction-related events. 100 km south of the GVP, near Polatlı, Ankara, basaltic rocks that cover large areas are intercalated with the Miocene deposits of the Beypazarı basin, an intra-continental subsidence zone at the southwest of the GVP. Field observations, geochemistry and K-Ar age dating of the Polatlı volcanites show that they are Early (19.9 Ma) to mid (14.1 Ma) Miocene in age, covering an area as large as 215 km 2. Variations in lava thickness and the thickness of the underlying silicified/baked zones suggest that the basaltic lavas erupted from a southern source, possibly from the Eskişehir fault zone, and flowed northwards. Most Polatlı samples have chemical compositions that indicate derivation from a mantle source with crustal contamination during ascent. They do not display any characteristic to suggest a subductional component. Although the GVP and Polatlı lavas formed close in time and space, they were derived from different mantle sources. Considering the positions of these two magmatic regions with regard to the Tethyan suture zone, we propose that the mantle beneath the GVP and near the suture zone memorised the earlier subduction while the mantle beneath Polatlı that is located about 100 km further from the suture zone remained apparently unchanged. After a significant volume of magma was consumed in the GVP, a later (˜10 My) and last activity (Güvem activity) has produced quantitatively much less basaltic rocks where this subductional signature seems to completely disappear. Considering that the western Anatolian crust is proposed to undergo extension since the

  15. 78 FR 48180 - Consolidation of Officer in Charge, Marine Inspection For Outer Continental Shelf Activities...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-07

    ... SECURITY Coast Guard Consolidation of Officer in Charge, Marine Inspection For Outer Continental Shelf Activities; Eighth Coast Guard District AGENCY: Coast Guard, DHS. ACTION: Notice and request for comments. SUMMARY: The Coast Guard is considering establishing a single Officer in Charge, Marine Inspection...

  16. 78 FR 5836 - Adjustment of Service Fees for Outer Continental Shelf Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE INTERIOR Bureau of Ocean Energy Management Adjustment of Service Fees for Outer Continental Shelf Activities... updated in 2008, with Federal Register Notice 73 FR 49943. BOEM is now adjusting various cost...

  17. Atlantic update, July 1986--June 1990: Outer Continental Shelf oil and gas activities

    SciTech Connect

    Karpas, R.M.; Gould, G.J.

    1990-10-01

    This report describes outer continental shelf oil and gas activities in the Atlantic Region. This edition of the Atlantic Update includes an overview of the Mid-Atlantic Planning Area and a summary of the Manteo Prospect off-shore North Carolina. 6 figs., 8 tabs.

  18. Active diapirism and slope steepening, northern Gulf of Mexico continental slope.

    USGS Publications Warehouse

    Martin, R.G.; Bouma, A.H.

    1982-01-01

    Large diapiric and nondiapiric masses of Jurassic salt and Tertiary shale underlie the northern Gulf of Mexico continental slope and adjacent outer continental shelf. Local steepening of the sea floor in response to the vertical growth of these structures is a serious concern to those involved in the site selection and the construction of future oil and gas production and transportation facilities in this frontier petroleum province. The evidence given in this paper supports the conclusion that the present continental slope region of the northern Gulf of Mexico is undergoing active diapirism and consequent slope steepening. Because most of the sediment on the flanks of diapiric structures consists of underconsolidated muds, slumping will take place regularly in response to further diapiric movement.-from Authors

  19. Understanding Tensions: Activity Systems Analysis of Cross-Continental Collaboration

    ERIC Educational Resources Information Center

    Ryder, LanHui Zhang; Yamagata-Lynch, Lisa

    2014-01-01

    Using the lens of Vygotsky's sociocultural theory, activity theory, and Engeström's activity systems analysis, this qualitative study explores students' experiences in the context of a sixteen-week transpacific collaboration between seven students at Northern Illinois University (NIU) and seven students from Shandong Normal…

  20. High Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    NASA Astrophysics Data System (ADS)

    Weldesenbet, S. F.; Wohnlich, S.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS (< 500mg/l) Ca-Mg-HCO3 dominated water at recharge area in the highlands and escarpments evolve progressively into Ca-Na-HCO3 and Na-Ca-HCO3 type waters along the rift ward groundwater flow paths. These waters finally appear as moderate TDS (mean 960mg/l) Na-HCO3 type and as high TDS (> 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (<30mg/l) thermal waters indicated a dilution by cold waters. Laboratory batch leaching experiments showed that fast dissolution of fluoride from the sediment samples suddenly leached into the interacting water at the first one hour and then remain stable throughout the experiment. The concentrations of leached fluoride from the hot spring deposits, the lacustrine sediments, and the pyroclastic rock are usually low (1% of the total or less than

  1. Fluoride and Geothermal Activities In Continental Rift Zones, Ethiopia

    NASA Astrophysics Data System (ADS)

    Weldesenbet, S. F.

    2012-12-01

    The Central Main Ethiopian Rift basin is a continental rift system characterized by volcano-tectonic depression endowed with huge geothermal resource and associated natural geochemical changes on groundwater quality. Chemical composition of groundwater in the study area showed a well defined trend along flow from the highland and escarpment to the rift floor aquifer. The low TDS (< 500mg/l) Ca-Mg-HCO3 dominated water at recharge area in the highlands and escarpments evolve progressively into Ca-Na-HCO3 and Na-Ca-HCO3 type waters along the rift ward groundwater flow paths. These waters finally appear as moderate TDS (mean 960mg/l) Na-HCO3 type and as high TDS (> 1000 mg/l) Na-HCO3-Cl type in volcano-lacustrine aquifers of the rift floor. High concentrations of fluoride (up to 97.2 mg/l) and arsenic (up to 98μg/l) are recognized feature of groundwaters which occur mostly in the vicinity of the geothermal fields and the rift lakes in the basin. Fluoride and arsenic content of dry volcaniclastic sediments close to these areas are in the range 666-2586mg/kg and 10-13mg/kg respectively. The relationship between fluoride and calcium concentrations in groundwaters showed negative correlation. Near-equilibrium state attained between the mineral fluorite (CaF2) and the majority of fluoride-rich (>30mg/l) thermal groundwater and shallow cold groundwater. This indicated that the equilibrium condition control the high concentration of fluoride in the groundwaters. Whereas undersaturation state of fluorite in some relatively low-fluoride (<30mg/l) thermal waters indicated a dilution by cold waters. Laboratory batch leaching experiments showed that fast dissolution of fluoride from the sediment samples suddenly leached into the interacting water at the first one hour and then remain stable throughout the experiment. The concentrations of leached fluoride from the hot spring deposits, the lacustrine sediments, and the pyroclastic rock are usually low (1% of the total or less than

  2. The role of continental collision in the separation of Arabia from Africa and the formation of the Dead Sea Fault

    NASA Astrophysics Data System (ADS)

    Wortel, R.; Meijer, P. Th.

    2012-04-01

    The separation of Arabia from Africa has been proposed to result from the collision-induced stress field in the NE corner of the former African plate (see Bellahsen et al., ESPL, 2003). Using this proposed mechanism as a starting point we numerically model the lithospheric stress field resulting from the collision induced changes in boundary forces, with emphasis on temporal and spatial variations. The collisional segment of the Africa/Arabia-Eurasia plate boundary gradually increases in length in E-SE direction. The stress field results show overall SW-NE tension in Arabia just prior to collision, followed by a drastic reduction in tensional stress upon collision. In the vicinity of the Owen Fracture Zone, however, tensional stresses remain high. At the same time the stress level in the Red Sea region is very moderate, thus not indicating simultaneous rifting. Since the initiation of rifting postdates the collision, we consider the high tensional stresses (after collision) at the eastern boundary to have started rift formation (in the present-day Gulf of Aden) towards the Afar region. Upon incorporation of a propagating rift the model results show two important changes: (1) near the tip of the propagating rift, stress concentration leads to high tensional stresses, and the rifting process appears to becomes self-sustaining; (2) the orientation of the tensional stress axis rotates clockwise with the changing boundary conditions along the plate contact during ongoing collision and rift propagation. When the rift arrives in the northern part of the Red Sea area, the direction of the tensional stress axis has rotated towards NW-SE, promoting rifting in the Gulf of Aqaba, rather than in the Gulf of Suez region. We further explore the role of the (evolution of the) subduction/collision process in, specifically, the formation of the Dead Sea Fault. In particular, we address the following three questions: (a) Was collision induced rifting able to create the present

  3. The role of continental collision in the separation of Arabia from Africa and the formation of the Dead Sea Fault

    NASA Astrophysics Data System (ADS)

    Wortel, M. J.; Meijer, P. T.

    2011-12-01

    The separation of Arabia from Africa has been proposed to result from the collision induced stress field in the NE corner of the former African plate (see Bellahsen et al., ESPL, 2003). Using this proposed mechanism as a starting point we numerically model the lithospheric stress field resulting from the collision induced changes in boundary forces, with emphasis on temporal and spatial variations. The collisional segment of the Africa/Arabia-Eurasia plate boundary gradually increases in length in E-SE direction. The stress field results show overall SW-NE tension in Arabia just prior to collision, followed by a drastic reduction in tensional stress upon collision. In the vicinity of the Owen Fracture Zone, however, tensional stresses remain high. At the same time the stress level in the Red Sea region is very moderate, thus not indicating simultaneous rifting. Since the initiation of rifting postdates the collision, we consider the high tensional stresses (after collision) at the eastern boundary to have started rift formation (in the present-day Gulf of Aden) towards the Afar region. Upon incorporation of a propagating rift the model results show two important changes: (1) near the tip of the propagating rift, stress concentration leads to high tensional stresses, and the rifting process appears to becomes self-sustaining; (2) the orientation of the tensional stress axis rotates clockwise with the changing boundary conditions along the plate contact during ongoing collision and rift propagation. When the rift arrives in the northern part of the Red Sea area, the direction of the tensional stress axis has rotated towards NW-SE, promoting rifting in the Gulf of Aqaba, rather than in the Gulf of Suez region. We further pay special attention to the following three questions: (a) Was collision induced rifting able to create the present-day Dead Sea Fault as a new plate boundary, over its entire length ? (b) Did the stress field evolution originally favor a northward

  4. The speciation of marine particulate iron adjacent to active and passive continental margins

    NASA Astrophysics Data System (ADS)

    Lam, Phoebe J.; Ohnemus, Daniel C.; Marcus, Matthew A.

    2012-03-01

    We use synchrotron-based chemical-species mapping techniques to compare the speciation of suspended (1-51 μm) marine particulate iron collected in two open ocean environments adjacent to active and passive continental margins. Chemical-species mapping provides speciation information for heterogeneous environmental samples, and is especially good for detecting spectroscopically distinct trace minerals and species that could not be detectable by other methods. The average oxidation state of marine particulate iron determined by chemical-species mapping is comparable to that determined by standard bulk X-ray Absorption Near Edge Structure spectroscopy. Using chemical-species mapping, we find that up to 43% of particulate Fe in the Northwest Pacific at the depth of the adjacent active continental margin is in the Fe(II) state, with the balance Fe(III). In contrast, particulate iron in the eastern tropical North Atlantic, which receives the highest dust deposition on Earth and is adjacent to a passive margin, is dominated by weathered and oxidized Fe compounds, with Fe(III) contributing 90% of total iron. The balance is composed primarily of Fe(II)-containing species, but we detected individual pyrite particles in some samples within an oxygen minimum zone in the upper thermocline. Several lines of evidence point to the adjacent Mauritanian continental shelf as the source of pyrite to the water column. The speciation of suspended marine particulate iron reflects the mineralogy of iron from the adjacent continental margins. Since the solubility of particulate iron has been shown to be a function of its speciation, this may have implications for the bioavailability of particulate iron adjacent to passive compared to active continental margins.

  5. Active mud volcanoes on the continental slope of the Canadian Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Paull, C. K.; Dallimore, S. R.; Caress, D. W.; Gwiazda, R.; Melling, H.; Riedel, M.; Jin, Y. K.; Hong, J. K.; Kim, Y.-G.; Graves, D.; Sherman, A.; Lundsten, E.; Anderson, K.; Lundsten, L.; Villinger, H.; Kopf, A.; Johnson, S. B.; Hughes Clarke, J.; Blasco, S.; Conway, K.; Neelands, P.; Thomas, H.; Côté, M.

    2015-09-01

    Morphologic features, 600-1100 m across and elevated up to 30 m above the surrounding seafloor, interpreted to be mud volcanoes were investigated on the continental slope in the Beaufort Sea in the Canadian Arctic. Sediment cores, detailed mapping with an autonomous underwater vehicle, and exploration with a remotely operated vehicle show that these are young and actively forming features experiencing ongoing eruptions. Biogenic methane and low-chloride, sodium-bicarbonate-rich waters are extruded with warm sediment that accumulates to form cones and low-relief circular plateaus. The chemical and isotopic compositions of the ascending water indicate that a mixture of meteoric water, seawater, and water from clay dehydration has played a significant role in the evolution of these fluids. The venting methane supports extensive siboglinid tubeworms communities and forms some gas hydrates within the near seafloor. We believe that these are the first documented living chemosynthetic biological communities in the continental slope of the western Arctic Ocean.

  6. PTt path in metamorphic rocks of the Khoy region (northwest Iran) and their tectonic significance for Cretaceous Tertiary continental collision

    NASA Astrophysics Data System (ADS)

    Azizi, H.; Moinevaziri, H.; Mohajjel, M.; Yagobpoor, A.

    2006-06-01

    Metamorphic rocks in the Khoy region are exposed between obducted ophiolites to the southwest and sedimentary rocks of Precambrian-Paleozoic age to the northeast. The Qom formation (Oligocene-Miocene) with a basal conglomerate transgressively overlies all of these rocks. The metamorphic rocks consist of both metasediments and metabasites. The metasediments are micaschist, garnet-staurolite schist and garnet-staurolite sillimanite schist with some meta-arkose, marble and quartzite. The metabasites are metamorphosed to greenschist and amphibolite facies from a basaltic and gabbroic protolith of tholeiitic and calc-alkaline rocks. Geothermobarometry based on the equivalence of minerals stability and their paragenesis in these rocks and microprobe analyses by several different methods indicate that metamorphism occurred in a temperature range between 450 and 680 °C at 5.5 and 7.5 kb pressure. Rims of minerals reveal a considerable decrease of pressure (<2 kb) and insignificant decrease of temperature. The PTt path of this metamorphism is normal. The MFG line passes above the triple junction of Al 2SiO 5 polymorphs, and the average geothermal gradient during metamorphism was from 27 to 37 °C/km, which is more concordant with the temperature regime of collision zones. We infer that crustal thickening during post-Cretaceous (possibly Eocene) collision of the Arabian plate and the Azerbaijan-Albourz block was the main factor that caused the metamorphism in the studied area.

  7. Syn-collisional granitoids in the Qilian Block on the Northern Tibetan Plateau: A long-lasting magmatism since continental collision through slab steepening

    NASA Astrophysics Data System (ADS)

    Huang, Hui; Niu, Yaoling; Mo, Xuanxue

    2016-03-01

    In this paper we present a new model that can explain the large zircon age spectrum of ~ 510 - 420 Ma within a single sample from the Gangcha (Gcha) biotite granodiorite and the Huangyuan (HY) two-mica monzogranite on the northern Tibetan Plateau. The large age spread recorded in zircons is characteristic of granitoid samples from the studied region, which is best explained by the long-lasting magmatism since the onset of continental collision at ~ 500 Ma, followed by slab steepening and the ultimate slab break-off at ~ 450 Ma. These granitoids have a large major and trace element compositional variation, but limited initial Sr (ISr[450] = 0.709 to 0.715), Nd (ԐNd[450] = - 6.5 to - 3.7), Hf (ԐHf[450] = - 4.3 to 1.5) and Pb (206Pb/204Pb[450] = 17.70 to 17.17; 207Pb/204Pb[450] = 15.60 to 15.69; 208Pb/204Pb[450] = 38.04 to 38.73) isotopic variation. The small negative whole rock ԐNd[450] and ԐHf[450] values are most consistent with the granitoid source being dominated by subducted seafloor materials. The inherited zircons with large negative ԐHf[450] values (e.g. - 50) are indicative of input from the lower continental crust and subducted sediments. The correlated variations among major elements, trace elements and radiogenic isotopes are best interpreted as reflecting melting-induced mixing of a compositionally heterogeneous source with superimposed effect of varying extent of fractional crystallization and crustal assimilation. The inherited zircons of Palaeo-Proterozoic age and the Archean crustal model ages signify the involvement of ancient basement rocks.

  8. Morphology of turbidite systems within an active continental margin (the Palomares Margin, western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Perez-Hernandez, S.; Comas, M. C.; Escutia, C.

    2014-08-01

    The Palomares Margin, an NNE-SSW segment of the South Iberian Margin located between the Alboran and the Algerian-Balearic basins, is dissected by two major submarine canyon systems: the Gata (in the South) and the Alías-Almanzora (in the North). New swath bathymetry, side-scan sonar images, accompanied by 5 kHz and TOPAS subbottom profiles, allow us to recognize these canyons as Mediterranean examples of medium-sized turbidite systems developed in a tectonically active margin. The Gata Turbidite System is confined between residual basement seamounts and exhibits incised braided channels that feed a discrete deep-sea fan, which points to a dominantly coarse-grained turbiditic system. The Alías-Almanzora Turbidite System, larger and less confined, is a good example of nested turbiditic system within the canyon. Concentric sediment waves characterize the Alías-Almanzora deep-sea fan, and the size and acoustic character of these bedforms suggest a fine-grained turbidite system. Both canyons are deeply entrenched on a narrow continental shelf and terminate at the base of the continental slope as channels that feed deep sea fans. While the Alías-Almanzora Turbidite System is the offshore continuation of seasonal rivers, the Gata Turbidite System is exclusively formed by headward erosion along the continental slope. In both cases, left-lateral transpressive deformation influences their location, longitudinal profiles, incision at the upper sections, and canyon bending associated with specific fault segments.

  9. Relative earthquake location for remote offshore and tectonically active continental regions using surface waves

    NASA Astrophysics Data System (ADS)

    Cleveland, M.; Ammon, C. J.; Vandemark, T. F.

    2015-12-01

    Earthquake locations are a fundamental parameter necessary for reliable seismic monitoring and seismic event characterization. Within dense continental seismic networks, event locations can be accurately and precisely estimated. However, for many regions of interest, existing catalog data and traditional location methods provide neither accurate nor precise hypocenters. In particular, for isolated continental and offshore areas, seismic event locations are estimated primarily using distant observations, often resulting in inaccurate and imprecise locations. The use of larger, moderate-size events is critical to the construction of useful travel-time corrections in regions of strong geologic heterogeneity. Double difference methods applied to cross-correlation measured Rayleigh and Love wave time shifts are an effective tool at providing improved epicentroid locations and relative origin-time shifts in these regions. Previous studies have applied correlation of R1 and G1 waveforms to moderate-magnitude vertical strike-slip transform-fault and normal faulting earthquakes from nearby ridges. In this study, we explore the utility of phase-match filtering techniques applied to surface waves to improve cross-correlation measurements, particularly for smaller magnitude seismic events. We also investigate the challenges associated with applying surface-wave location methods to shallow earthquakes in tectonically active continental regions.

  10. Comparison of marine gas hydrates in sediments of an active and passive continental margin

    USGS Publications Warehouse

    Kvenvolden, K.A.

    1985-01-01

    Two sites of the Deep Sea Drilling Project in contrasting geologic settings provide a basis for comparison of the geochemical conditions associated with marine gas hydrates in continental margin sediments. Site 533 is located at 3191 m water depth on a spit-like extension of the continental rise on a passive margin in the Atlantic Ocean. Site 568, at 2031 m water depth, is in upper slope sediment of an active accretionary margin in the Pacific Ocean. Both sites are characterized by high rates of sedimentation, and the organic carbon contents of these sediments generally exceed 0.5%. Anomalous seismic reflections that transgress sedimentary structures and parallel the seafloor, suggested the presence of gas hydrates at both sites, and, during coring, small samples of gas hydrate were recovered at subbottom depths of 238m (Site 533) and 404 m (Site 568). The principal gaseous components of the gas hydrates wer methane, ethane, and CO2. Residual methane in sediments at both sites usually exceeded 10 mll-1 of wet sediment. Carbon isotopic compositions of methane, CO2, and ??CO2 followed parallel trends with depth, suggesting that methane formed mainly as a result of biological reduction of oxidized carbon. Salinity of pore waters decreased with depth, a likely result of gas hydrate formation. These geochemical characteristics define some of the conditions associated with the occurrence of gas hydrates formed by in situ processes in continental margin sediments. ?? 1984.

  11. Role of local to regional-scale collisions in the closure history of the Southern Neotethys, exemplified by tectonic development of the Kyrenia Range active margin/collisional lineament, N Cyprus

    NASA Astrophysics Data System (ADS)

    Robertson, Alastair; Kinnaird, Tim; McCay, Gillian; Palamakumbura, Romesh; Chen, Guohui

    2016-04-01

    Active margin processes including subduction, accretion, arc magmatism and back-arc extension play a key role in the diachronous, and still incomplete closure of the S Neotethys. The S Neotethys rifted along the present-day Africa-Eurasia continental margin during the Late Triassic and, after sea-floor spreading, began to close related to northward subduction during the Late Cretaceous. The northern, active continental margin of the S Neotethys was bordered by several of the originally rifted continental fragments (e.g. Taurides). The present-day convergent lineament ranges from subaqueous (e.g. Mediterranean Ridge), to subaerial (e.g. SE Turkey). The active margin development is partially obscured by microcontinent-continent collision and post-collisional strike-slip deformation (e.g. Tauride-Arabian suture). However, the Kyrenia Range, N Cyprus provides an outstanding record of convergent margin to early stage collisional processes. It owes its existence to strong localised uplift during the Pleistocene, which probably resulted from the collision of a continental promontory of N Africa (Eratosthenes Seamount) with the long-lived S Neotethyan active margin to the north. A multi-stage convergence history is revealed, mainly from a combination of field structural, sedimentological and igneous geochemical studies. Initial Late Cretaceous convergence resulted in greenschist facies burial metamorphism that is likely to have been related to the collision, then rapid exhumation, of a continental fragment (stage 1). During the latest Cretaceous-Palaeogene, the Kyrenia lineament was characterised by subduction-influenced magmatism and syn-tectonic sediment deposition. Early to Mid-Eocene, S-directed thrusting and folding (stage 2) is likely to have been influenced by the suturing of the Izmir-Ankara-Erzincan ocean to the north ('N Neotethys'). Convergence continued during the Neogene, dominated by deep-water terrigenous gravity-flow accumulation in a foredeep setting

  12. Collision tectonics

    SciTech Connect

    Coward, M.P.; Ries, A.C.

    1985-01-01

    The motions of lithospheric plates have produced most existing mountain ranges, but structures produced as a result of, and following the collision of continental plates need to be distinguished from those produced before by subduction. If subduction is normally only stopped when collision occurs, then most geologically ancient fold belts must be collisional, so it is essential to recognize and understand the effects of the collision process. This book consists of papers that review collision tectonics, covering tectonics, structure, geochemistry, paleomagnetism, metamorphism, and magmatism.

  13. 76 FR 79705 - Information Collection Activities: Operations in the Outer Continental Shelf for Minerals Other...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-22

    ... the Outer Continental Shelf for Minerals Other than Oil, Gas, and Sulphur; Submitted for Office of..., ``Operations in the Outer Continental Shelf for Minerals Other than Oil, Gas, and Sulphur''. DATES: Submit... Continental Shelf for Minerals other than Oil, Gas, and Sulphur. OMB Control Number: 1014-NEW. Abstract:...

  14. 77 FR 15118 - Information Collection Activities: Operations in the Outer Continental Shelf for Minerals Other...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-14

    ... Continental Shelf for Minerals Other Than Oil, Gas, and Sulphur; Submitted for Office of Management and Budget... Continental Shelf for Minerals Other than Oil, Gas, and Sulphur. This notice also provides the public a second... 282, Operations in the Outer Continental Shelf for Minerals Other than Oil, Gas, and Sulphur....

  15. Investigation of shallow gas hydrate occurrence and gas seep activity on the Sakhalin continental slope, Russia

    NASA Astrophysics Data System (ADS)

    Jin, Young Keun; Baranov, Boris; Obzhirov, Anatoly; Salomatin, Alexander; Derkachev, Alexander; Hachikubo, Akihiro; Minami, Hrotsugu; Kuk Hong, Jong

    2016-04-01

    The Sakhalin continental slope has been a well-known gas hydrate area since the first finding of gas hydrate in 1980's. This area belongs to the southernmost glacial sea in the northern hemisphere where most of the area sea is covered by sea ice the winter season. Very high organic carbon content in the sediment, cold sea environment, and active tectonic regime in the Sakhalin slope provide a very favorable condition for occurring shallow gas hydrate accumulation and gas emission phenomena. Research expeditions under the framework of a Korean-Russian-Japanese long-term international collaboration projects (CHAOS, SSGH-I, SSGH-II projects) have been conducted to investigate gas hydrate occurrence and gas seepage activities on the Sakhalin continental slope, Russia from 2003 to 2015. During the expeditions, near-surface gas hydrate samples at more than 30 sites have been retrieved and hundreds of active gas seepage structures on the seafloor were newly registered by multidisciplinary surveys. The gas hydrates occurrence at the various water depths from about 300 m to 1000 m in the study area were accompanied by active gas seepage-related phenomena in the sub-bottom, on the seafloor, and in the water column: well-defined upward gas migration structures (gas chimney) imaged by high-resolution seismic, hydroacoustic anomalies of gas emissions (gas flares) detected by echosounders, seafloor high backscatter intensities (seepage structures) imaged by side-scan sonar and bathymetric structures (pockmarks and mounds) mapped by single/multi-beam surveys, and very shallow SMTZ (sulphate-methane transition zone) depths, strong microbial activities and high methane concentrations measured in sediment/seawater samples. The highlights of the expeditions are shallow gas hydrate occurrences around 300 m in the water depth which is nearly closed to the upper boundary of gas hydrate stability zone in the area and a 2,000 m-high gas flare emitted from the deep seafloor.

  16. Hydrothermal Petroleum in Active Continental Rift: Lake Chapala, Western Mexico, Initial Results.

    NASA Astrophysics Data System (ADS)

    Zarate-del Valle, P. F.; Simoneit, B. R.; Ramirez-Sanchez, H. U.

    2003-12-01

    Lake Chapala in western Mexico is located partially in the Citala Rift, which belongs to the well-known neotectonic Jalisco continental triple junction. The region is characterized by active volcanism (Ceboruco, Volcan de Fuego), tectonic (1995 earthquake, M=8, 40-50 mm to SW) and hydrothermal (San Juan Cosala & Villa Corona spas and La Calera sinter deposit) activities. Hydrothermal petroleum has been described in active continental rift (East African Rift) and marine spreading zones (Guaymas Basin, Gulf of California). In 1868 the Mexican local press reported that manifestations of bitumen were appearing in front of the Columba Cap on the mid south shore of Lake Chapala. This bitumen is linked to the lake bottom and when the water level decreases sufficiently it is possible to access these tar bodies as islands. Because of these manifestations the Mexican oil company (PEMEX) drilled an exploration well (2,348m) at Tizapan El Alto without success. Hydrothermal activity is evident in the tar island zone as three in-shore thermal springs (26.8 m depth, 48.5° C, pH 7.8 and oriented N-S). The preliminary analyses by GC-MS of the tar from these islands indicate hydrothermal petroleum derived from lake sedimentary organic matter, generated at low temperatures (150° -200° C). The tars contain no n-alkanes, no PAH or other aromatics, but a major UCM of branched and cyclic hydrocarbons and mature biomarkers derived from lacustrine biota. The biomarkers consist of mainly 17α (H),21β (H)-hopanes ranging from C27 to C34 (no C28), gammacerane, tricyclic terpanes (C20-C26), carotane and its cracking products, and drimanes (C14-C16). The biomarker composition indicates an organic matter source from bacteria and algae, typical of lacustrine ecosystems. 14C dating of samples from two tar islands yielded ages exceeding 40 kyrs, i.e., old carbon from hydrothermal/tectonic remobilization of bitumen from deeper horizons to the surface. The occurrence of hydrothermal petroleum in

  17. The role of different magnetotelluric tensor relationships in detecting partial melt in continental collision zones: Results from synthetic models and real data

    NASA Astrophysics Data System (ADS)

    Campanya i Llovet, J.; Ledo, J.; Jones, A. G.; Queralt, P.; Marcuello, A.; Liesa, M.; Muñoz, J.

    2013-12-01

    Three magnetotelluric (MT) tensor relationships - the single-station MT impedance tensor, the single-station vertical geomagnetic transfer function (GTF) and the multiple-station horizontal geomagnetic transfer function (HGTF) - were investigated for their role in detecting the presence of partial melting in continental collision zones. Synthetic models based on previous studies were used to characterize the sensitivity of each tensor relationship constraining the presence of partial melt at lower-crustal and upper-mantle depths. From the MT response of the synthetic models, each type of data has been inverted separately and jointly with the others, thus determining the properties and advantages of each when modeling the subsurface. Non-linear sensitivity tests have been carried out to determine the resolution that can be expected when constraining electrical resistivity anomalies associated with the presence of partial melt. The electrical resistivity anomalies associated with different amounts of partial melt were calculated using the two phases of Archie's law and Hashin Shtrikman extremal bounds. The results have been compared with the sensitivity of the MT tensor relationships, thus determining the resolution that can be expected in the detection of partial melt at lower-crustal and upper-mantle depths. Equivalent analyses have been performed using real MT data from a survey carried out in the Pyrenees. The data comprise a total of 82 broadband MT sites and 29 long period MT sites distributed along four profiles across the Pyrenean mountain range between the Atlantic Ocean and the Mediterranean Sea. The results show the presence of a low-electrical-resistivity structure that has been associated with partial melting of the Iberian subducted lower crust. This anomaly has been constrained below three of the MT profiles but seems to be absent below the Eastern Pyrenees MT profile. A non-linear sensitivity tests was undertaken to ensure that the absence of this

  18. Triassic post collision igneous activity and granulite facies metamorphic event in the Yangpyeong area, South Korea and its meaning to the tectonics of Northeast Asia

    NASA Astrophysics Data System (ADS)

    Lee, S.; Oh, C.

    2009-12-01

    The Korean peninsula is tectonically positioned in the eastern margin of the Asia continent and the Gyeonggi massif is situated in the center part of Korean peninsula. Triassic (231 Ma) eclogite was first found in the Hongseong area, the southwestern part of the Gyeonggi Massif, which suggested that the Hongseong area is the extension of Triassic collision belt between the North and South China blocks, in China. The 257-226 post-collisional mangerite was also found in the Odesan area, the eastern part of Gyeonggi massif. Based on these new findings, it was proposed that the line connecting Hongseong and Odesan areas is the collision belt between the North and South China blocks. It was also reported that 247 Ma ultrahigh temperature metamorphism occurred together with the intrusion of mangerite in the Odesan area indicating that regional metamorphism occurred together with the post-collision igneous activity. The Yangpyeong area locates in the middle part of the Hongseong-Odesan collision belt. The area mainly consists of Precambrian migmatitic gneiss which was intruded by Triassic igneous complex. The igneous complex mainly consists of gabbro and porpyritic syeno-diorite and SHRIMP age dating indicates that they intruded at 227 ± 4 Ma. They are shoshonitic and high-K series and have high Ba, Sr contents. They show LREE enriched pattern and Nb, Ta, P, Ti depletion in the chondrite- and primitive-mantle-normalized trace element patterns, respectively. In the tectonic discrimination diagrams, gabbros are plotted in the within plate tectonic field and porpyritic syeno-diorites are plotted in the Post-collision field. These geochemical characters indicate that they formed in the within plate after continental collision. Two metamorphic ages (1861 ± 6 Ma, and 235 ± 6 Ma) are obtained from the migmatitic gneiss. The peak metamorphic conditions of the first Precambrian metamorphism are 750-780°C and 8-10 kbar indicating intermediate-P/T metamorphism. On the other hand

  19. New Isotopic Constraints on the Sources of Methane at Sites of Active Continental Serpentinization

    NASA Astrophysics Data System (ADS)

    Wang, D. T.; Gruen, D.; Morrill, P. L.; Rietze, A.; Nealson, K. H.; Kubo, M. D.; Cardace, D.; Schrenk, M. O.; Hoehler, T. M.; McCollom, T. M.; Etiope, G.; Hosgormez, H.; Schoell, M.; Ono, S.

    2014-12-01

    of methane, and the flow of energy and carbon, in areas of active continental serpentinization. [1] Ono et al. (2014) Anal. Chem. 86, 6487. [2] Morrill et al. (2013) Geochim. Cosmochim. Acta 109, 222. [3] Cardace et al. (2013) Sci. Dril. 16, 45. [4] Etiope et al. (2011) Earth Planet. Sci. Lett. 310, 96.

  20. Diabatic heating profiles over the continental convergence zone during the monsoon active spells

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Rajib; Sur, Sharmila; Joseph, Susmitha; Sahai, A. K.

    2013-07-01

    The present paper aims to bring out the robust common aspects of spatio-temporal evolution of diabatic heating during the monsoon intraseasonal active phases over the continental tropical convergence zone (CTCZ). The robustness of spatio-temporal features is determined by comparing the two state-of-the art reanalyses: NCEP Climate Forecast System reanalysis and Modern ERA Retrospective Analysis. The inter-comparison is based on a study period of 26 years (1984-2009). The study confirms the development of deep heating over the CTCZ region during the active phase and is consistent between the two datasets. However, the detailed temporal evolution of the vertical structure (e.g., vertical tilts) of heating differs at times. The most important common feature from both the datasets is the significant vertical redistribution of heating with the development of shallow (low level) heating and circulation over the CTCZ region 3-7 days after the peak active phase. The shallow circulation is found to be associated with increased vertical shear and relative vorticity over certain regions in the subcontinent. This increased vertical shear and relative vorticity in the lower levels could be crucial in the sustenance of rainfall after the peak active phase. Model experiments with linear dynamics affirm the role of shallow convection in increasing the lower level circulation as observed.

  1. Middle Triassic magma mixing in an active continental margin: Evidence from mafic enclaves and host granites from the Dewulu pluton in West Qinling, central China

    NASA Astrophysics Data System (ADS)

    Huang, X.; Mo, X.; Yu, X.

    2015-12-01

    The Qinling-Dabie-Sulu orogen was formed through the collision of the North and South China blocks, but the precise timing of the closure of the Paleo-Tethys ocean between the two blocks remains debated. Large volumes of Triassic granites associated with mafic microgranular enclaves (MMEs) were emplaced in the Qinling terrane. This paper presents field observations, petrography, geochronology and geochemistry of the MMEs and their host granites from the Dewulu pluton in West Qinling. The host rocks comprise granodiorite and granodioritic porphyry, and the The MMEs range in composition from gabbroic diorite to diorite. Zircon LA-ICP-MS U-Pb ages suggest that the granites and MMEs were coeval at ca. 245 Ma. The granites are relatively enriched in LILE and depleted in HFSE, and have evolved Sr-Nd-Pb and zircon Hf isotopic compositions [initial 87Sr/86Sr = 0.7070-0.7076, ɛNd(t) = -7.5 to -6.8, ɛHf(t) = -8.2 to -4.2], indicative of an origin from the amphibolitic lower crust. The near-primitive gabbro-dioritic MMEs bear a remarkable geochemical resemblance to the high-magnesium andesite (HMA), such as moderate SiO2 (~55 wt.%), low FeOT/MgO (~0.75), high Cr (268-308 ppm) and MgO (8.58-8.77 wt.%) with Mg# of ~70. Additionally, they exhibit lower initial 87Sr/86Sr, higher ɛNd(t) and ɛHf(t), and more radiogenic Pb isotopes than the dioritic MMEs which share similar isotopic compositions with the granites. These features, together with the presence of the specific minerals in the MMEs (e.g., felsic xenocrysts and acicular apatite), point to mixing process between the lower crust-derived magmas and the melts produced by the reaction of the subducting sediment-derived components and the overlying mantle. Taking into account the regional occurrence of synchronous plutonic-volcanic complexes (250-234 Ma) ranging from basaltic to granitic variants, we suggest that the Dewulu pluton formed in an active continental margin in response to the local extension triggered by the

  2. Episodic nature of earthquake activity in stable continental regions revealed by palaeoseismicity studies of Australian and North American Quaternary faults

    USGS Publications Warehouse

    Crone, A.J.; Machette, M.N.; Bowman, J.R.

    1997-01-01

    Palaeoseismic investigations of recent faulting in stable continental regions of Australia, North America and India show that these faults typically have a long-term behaviour characterised by episodes of activity separated by quiescent intervals of at least 10 000 and commonly 100 000 years or more. Long recurrence intervals such as these are well documented by detailed studies of the faults that ruptured during the 1986 Marryat Creek, South Australia and 1988 Tennant Creek, Northern Territory earthquakes. Thus, neotectonic features associated with stable continental region faults such as scarps and grabens commonly have subtle geomorphic expression and may be poorly preserved. Many potentially hazardous faults in stable continental regions are aseismic, which is one reason why the inventory of these faults is incomplete. Although they may be currently aseismic, faults in stable continental regions that are favourably oriented for movement in the current stress field could produce damaging earthquakes, often in unexpected places. Comprehensive palaeoseismic investigations of modern and prehistoric faulting events in stable continental regions are needed to understand the long-term behaviour of these faults, and thereby, improve seismic-hazard assessments.

  3. Lu-Hf geochronology on cm-sized garnets using microsampling: New constraints on garnet growth rates and duration of metamorphism during continental collision (Menderes Massif, Turkey)

    NASA Astrophysics Data System (ADS)

    Schmidt, Alexander; Pourteau, Amaury; Candan, Osman; Oberhänsli, Roland

    2015-12-01

    provides a precise age determination for prograde Barrovian metamorphism in the southern Menderes Massif, which so far was placed between 63 and 27 Ma on the basis of mica Rb-Sr and Ar-Ar dating. This study provides new constraints crucial to the understanding of the tectonic evolution of southwest Anatolia and the Aegean realm, as it yields a shorter outline for Alpine aged continental collision.

  4. Three-Dimensional Numerical Modeling of Crustal Growth at Active Continental Margins

    NASA Astrophysics Data System (ADS)

    Zhu, G.; Gerya, T.; Tackley, P. J.

    2011-12-01

    Active margins are important sites of new continental crust formation by magmatic processes related to the subduction of oceanic plates. We investigate these phenomena using a three-dimensional coupled petrological-geochemical-thermomechanical numerical model, which combines a finite-difference flow solver with a non-diffusive marker-in-cell technique for advection (I3ELVIS code, Gerya and Yuen, PEPI,2007). The model includes mantle flow associated with the subducting plate, water release from the slab, fluid propagation that triggers partial melting at the slab surface, melt extraction and the resulting volcanic crustal growth at the surface. The model also accounts for variations in physical properties (mainly density and viscosity) of both fluids and rocks as a function of local conditions in temperature, pressure, deformation, nature of the rocks, and chemical exchanges. Our results show different patterns of crustal growth and surface topography, which are comparable to nature, during subduction at active continental margins. Often, two trench-parallel lines of magmatic activity, which reflect two maxima of melt production atop the slab, are formed on the surface. The melt extraction rate controls the patterns of new crust at different ages. Moving free water reflects the path of fluids, and the velocity of free water shows the trend of two parallel lines of magmatic activity. The formation of new crust in particular time intervals is distributed in finger-like shapes, corresponding to finger-like and ridge-like cold plumes developed atop the subducting slabs (Zhu et al., G-cubed,2009; PEPI,2011). Most of the new crust is basaltic, formed from peridotitic mantle. Granitic crust extracted from melted sediment and upper crust forms in a line closer to the trench, and its distribution reflects the finger-like cold plumes. Dacitic crust extracted from the melted lower crust forms in a line farther away from the trench, and its distribution is anticorrelated with

  5. Impact of Activation Treatment and CCN/IN Concentrations on Simulations of A Continental Convective System

    NASA Astrophysics Data System (ADS)

    Rothenberg, D. A.; Wang, C.

    2014-12-01

    Aerosol play an important role in mediating cloud microphysics by serving as both cloud condensation and ice nuclei (CCN and IN). In mixed-phase, deep convective clouds, these CCN and IN can alter physical processes related to droplet activation and heterogeneous freezing, affecting the dynamics, microphysics, and ultimately evolution of the cloud. However, modifying the CCN and IN budget entrained into a cloud eventually leads to many simultaneous, competing microphysical processes which make it difficult to precisely predict how cloud properties will change. Here, we study the sensitivity of a continental convective system observed during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) in 2011 to changes in CCN and IN burden with the help of 2D and 3D cloud-resolving model simulations. We explore how the potential for convective invigoration is sensitive to the treatment of droplet activation at the cloud base by adopting an emulator of an adiabatic parcel model to parameterize the activation calculation. Furthermore, we study how changes in the IN budget can enhance the role of heterogeneous freezing and diminish the efficacy of homogeneous freezing above the -40C isotherm within the cloud. Since anvil ice is typically produced homogeneously, we also study how this shift in freezing mechanisms affects the size distributions and properties of the system's anvil cirrus. The in situ observations of anvil ice obtained during MACPEX and the ice nuclei residuals are used as a reference to constrain the simulations.

  6. Tectonic evolution of Late Cenozoic arc-continent collision in Taiwan

    SciTech Connect

    Teng, L.S. )

    1990-06-01

    The island of Taiwan is an active orogen formed by the collision between the Luzon arc and the Asian continent. The kinematic progression of the arc-continent collision can be reconstructed by superimposing the restored paleopositions of Luzon arc upon the precollisional Asian continental margin. The geological history of the collision can be interpreted from the rock records of the mountain ranges of Taiwan. By incorporating geological information into plate kinematics, the collision can be attributed to the northwesterly impingement of the Luzon arc upon the continental margin in the last 12 million years. During the initial stage of the collision, some of the continental materials might have been metamorphosed in the deep subduction zone, but no distinct effects can be perceived in the sedimentary record. In the Mio-Pliocene time (about 5 Ma), the accretionary wedge grew large enough to become a sediment source for the Luzon forearc basin and to induce foreland subsidence on the continental margin. In the early late Pliocene (about 3 Ma), drastic collision caused rapid uplift of the collision orogen that shed voluminous orogenic sediments into the forearc and foreland basins. Continued collision progressively accreted the forearc and foreland basins to the collision orogen from north to south to the present configuration.

  7. Arctic summary report: Outer Continental Shelf oil and gas activities in the Arctic and their onshore impacts

    NASA Astrophysics Data System (ADS)

    Lynch, C.; Slitor, D. L.; Rudolph, R. W.

    1985-01-01

    Issues and developments occuring in the Arctic Outer Continental Shelf subregion are discussed. The geology and hydrocarbon potential of the Diapir Field petroleum provinces are detailed. Recent lease sales, exploration activities, and the first development proposals for offshore areas of the North slope are considered. Issues relating to transporting resources from production islands to shore and various proposals for moving Arctic hydrocarbons to market are presented. Production projects onshore and possible support bases for offshore activity are also examined.

  8. Geothermal activity at continental rift Citala, Western Mexico, where Lake Chapala is emplaced: past and present

    NASA Astrophysics Data System (ADS)

    Zárate-del Valle, P. F.

    2003-04-01

    Lake Chapala is a tectonic lake developed on a continental rift named Citala (CRC) which belongs to a tectonically active zone in Western Mexico: the so-called Jalisco continental triple junction. Fossil sinter deposit, thermal spring, hydrothermal (hy) petroleum manifestation and hy alteration halo characterized the Lake Chapala basin. On the SE shore, outcrops a carbonate deposit named ``La Calera" (LC) which consists of a carbonate fossil sinter that measures 2 km in E-W direction and 600 m in N-S direction and overlays andesitic rock. With a thickness of approximately 5 m and a roughly horizontal attitude, the LC is characterized by a two-fold structure: when massive, it is colored in yellow brownish and grey and elsewhere it shows a pseudo-brecciated structure and when banded, yellow and dark millimetre alternated bands can be seen. The LC is marked by vuggy porosity and silica (quartz and chalcedony) vein lets. Under microscope a pseudo-micritic texture is observed; vugs coated by iron oxides, are filled with calcite, and/or quartz, chalcedony and clay minerals. Six samples of LC were analysed (LODC-UParis VI) for their stable isotopes (δ18O and δ13C): From δ13C{PDB} values we have two sets of data: -8.03 to -8.69 ppm that means a no contribution of organic carbon (oc) and -0.35 to -0.75 ppm meaning an important contribution of oc; from δ18O{PDB} values: -8.5 to -10.27 ppm we deduced a deposit in meteoric water with a temperature deposition higher than the surface. The CRC is characterized also by the presence of hydrothermal petroleum (hp): Inside the Chapala and ˜2 km from SE shore (Los Arcos) there are some small spots made of hp which look like islands (<3-4 m^2) linked to the bottom of the lake which consist of solid bitumen. Thermal springs (ths) occur both inside and outside the lake Chapala: the water in out-shore ths is of carbonate type (69^oC; ˜ 240 mg L-1 [HCO_3]^-; with one exception: the ths at the San Juan Cosalá spa (N shore), which is

  9. Shelfal sediment transport by undercurrents forces turbidity current activity during high sea level, Chile continental margin

    NASA Astrophysics Data System (ADS)

    Bernhardt, Anne; Hebbeln, Dierk; Regenberg, Marcus; Lückge, Andreas; Strecker, Manfred. R.

    2016-04-01

    Understanding the links between terrigenous sediment supply and marine transport and depositional processes along tectonically active margins is essential to decipher turbidite successions as potential archives of climatic and seismic forcings and to comprehend timing and quantity of marine clastic deposition. Sequence stratigraphic models predict coarse-grained terrigenous sediment delivery to deep-marine sites mainly during sea-level fall and lowstand. Marine clastic deposition during periods of transgression and highstand has been attributed to the continued geomorphic connectivity between terrestrial sediment sources and marine sinks (e.g., rivers connected to submarine canyons) often facilitated by narrow shelves, high sediment supply causing delta migration to the shelf edge, and/or abrupt increases in sediment supply due to climatic variability or catastrophic events. To decipher the controls on Holocene highstand turbidite deposition, we analyzed twelve sediment cores of spatially disparate, coeval Holocene turbidite systems along the Chile margin (29-40°S) with changing climatic and geomorphic characteristics but uniform changes of sea level. Intraslope basins in north-central Chile (29-33°S) offshore a narrow to absent shelf record a shut-off of turbidite activity during the Holocene. In contrast, core sites in south-central Chile (36-40°S) offshore a wide continental shelf have repeatedly experienced turbidite deposition during sea-level highstand conditions, even though most of the depocenters are not connected via canyons to sediment sources. The interplay of stable high sediment supply related to strong onshore precipitation in combination with a wide shelf, over which undercurrents move sediment towards the shelf edge, appears to control Holocene turbidite sedimentation and sediment export to the deep sea.

  10. Spatial association of Neoproterozoic continental arc I-type and post-collision A-type granitoids in the Arabian-Nubian Shield: The Wadi Al-Baroud Older and Younger Granites, North Eastern Desert, Egypt

    NASA Astrophysics Data System (ADS)

    El-Bialy, Mohammed Zaky; Omar, Mohamed M.

    2015-03-01

    The Neoproterozoic basement of Wadi Al-Baroud area located at the northern Eastern Desert (ED) of Egypt, at the northernmost segment of the Arabian-Nubian Shield (ANS), is comprised of two different granite suites. A large batholith ascribed to the Older Granite suite, extends across the boundary between the northern and central ED, and is intruded by two isolated plutons of the Younger Granite suite. The Older Granite suite includes gray-colored, massive to gneissose, granodiorites to tonalites typically containing microgranular mafic enclaves. These are calc-alkaline, magensian, metaluminous I-type granitoids, with high Sr contents, and depleted in Rb, Nb, Y and REE. The Younger Granite suite plutons are pink to red, biotite and two-mica monzogranites. These are peraluminous A-type granites exhibiting a high-K calc-alkaline nature, and varying between ferroan and magnesian type granites. The A-type granites of the Younger Granite suite are enriched in Ga, Y, HFSE and REE elements, and depleted in the LILE elements Ba, Sr and Rb and transition metals Cr, Ni, Co, Sc and V. Magmatic saturation temperatures indicate early crystallization of apatite at high temperature in the metaluminous I-type Older Granite suite, while in the peraluminous A-type Younger Granites its crystallization occurs later after separation of zircon and monazite. The plutons of the Younger Granite suite were generated during the post-collisional stage of the northern ANS, following collision between the juvenile ANS crust and the pre-Neoproterozoic continental blocks of west Gondwana. The emplacement of the Older Granite suite took place earlier, within a normally mature continental arc prior to the collision. These pre-collision granitoids evolved through assimilation-fractional crystallization processes from mantle-derived parental magmas, which have interacted with crustal materials during ascent and storage. The post-collisional Younger Granite suite seems to have been derived by high

  11. Turbidite paleoseismology along the active continental margin of Chile - Feasible or not?

    NASA Astrophysics Data System (ADS)

    Bernhardt, Anne; Melnick, Daniel; Hebbeln, Dierk; Lückge, Andreas; Strecker, Manfred R.

    2015-07-01

    Much progress has been made in estimating recurrence intervals of great and giant subduction earthquakes using terrestrial, lacustrine, and marine paleoseismic archives. Recent detailed records suggest these earthquakes may have variable recurrence periods and magnitudes forming supercycles. Understanding seismic supercycles requires long paleoseismic archives that record timing and magnitude of such events. Turbidite paleoseismic archives may potentially extend past earthquake records to the Pleistocene and can thus complement commonly shorter-term terrestrial archives. However, in order to unambiguously establish recurring seismicity as a trigger mechanism for turbidity currents, synchronous deposition of turbidites in widely spaced, isolated depocenters has to be ascertained. Furthermore, characteristics that predispose a seismically active continental margin to turbidite paleoseismology and the correct sample site selection have to be taken into account. Here we analyze 8 marine sediment cores along 950 km of the Chile margin to test for the feasibility of compiling detailed and continuous paleoseismic records based on turbidites. Our results suggest that the deposition of areally widespread, synchronous turbidites triggered by seismicity is largely controlled by sediment supply and, hence, the climatic and geomorphic conditions of the adjacent subaerial setting. The feasibility of compiling a turbidite paleoseismic record depends on the delicate balance between sufficient sediment supply providing material to fail frequently during seismic shaking and sufficiently low sedimentation rates to allow for coeval accumulation of planktonic foraminifera for high-resolution radiocarbon dating. We conclude that offshore northern central Chile (29-32.5°S) Holocene turbidite paleoseismology is not feasible, because sediment supply from the semi-arid mainland is low and almost no Holocene turbidity-current deposits are found in the cores. In contrast, in the humid region

  12. Relationship Between Accelerometer Load, Collisions, and Repeated High-Intensity Effort Activity in Rugby League Players.

    PubMed

    Gabbett, Tim J

    2015-12-01

    Triaxial accelerometers have been critical in providing information on the high-acceleration, low-velocity movements that occur in team sports. In addition, these sensors have proven to be useful in quantifying the activities that do not involve the vertical acceleration associated with locomotion (e.g., tackling, on-ground wrestling, and grappling). This study investigated the relationship between Player Load (PL), 2D Player Load (2DPL), and Player Load Slow (PL Slow), collisions, and repeated high-intensity effort (RHIE) activity in rugby league players. One hundred and eighty-two rugby league players (age, 24.3 ± 3.3 years) participated in this study. Movement was recorded using a global positioning system unit sampling at 10 Hz and triaxial accelerometer sampling at 100 Hz. Analysis was completed during 26 matches (totaling 386 appearances). Pearson product-moment correlation coefficients were used to determine relationships between PL, 2DPL, and PL Slow and total collisions and RHIE activity. When all players were considered, weak relationships were found between PL and the number of collisions and RHIE bouts performed. However, PL was strongly associated (p ≤ 0.05) with total distance, low-speed activity, high-speed running distance, total collisions, and the number of RHIE bouts for forwards and hookers. Weak and typically insignificant relationships were found between PL, 2DPL, and PL Slow and the number of collisions and RHIE bouts performed by the adjustables and outside backs positional groups. The relationships between PL and the number of collisions and RHIE bouts are stronger in positions where contact and repeated-effort demands are high. From a practical perspective, these results suggest that PL, 2DPL, and PL Slow offer useful "real-time" measures of collision and RHIE activity, particularly in forwards and hookers, to inform interchange strategies and ensure players are training at an adequate intensity. PMID:26196661

  13. Active Arc-Continent Accretion in Timor-Leste: New Structural Mapping and Quantification of Continental Subduction

    NASA Astrophysics Data System (ADS)

    Tate, G. W.; McQuarrie, N.; Bakker, R.; van Hinsbergen, D. J.; Harris, R. A.

    2010-12-01

    The island of Timor represents the active accretion of the Banda volcanic arc to the Australian continental margin. Arc accretion marks the final closure of an ocean basin in the canonic Wilson tectonic cycle, yet the incipient stages as visible now on Timor are still poorly understood. In particular, ocean closure brings continental material into the subduction zone as part of the down-going plate. The positive buoyancy of this subducting continental crust presents a complex problem in crustal dynamics, with possible effects on overall plate motions, migration and/or reversal of the active subduction zone, and the modes of faulting within the upper crust. New mapping in Timor-Leste has provided a detailed view of the structural repetition of Australian continental sedimentary units structurally below overriding Banda Arc material. The central Dili-Same transect begins in the north with the low-grade metamorphic Aileu Formation of Australian affinity, thrust over the time-equivalent more proximal Maubisse Formation to the south. These in turn are thrust over the Australian intra-continental strata, the Triassic Aitutu and the Permian Cribas Formations. The Aitutu and Cribas Formations are deformed in a series of faulted ENE-striking anticlines exposed along the central axis of Timor. The southern end of the transect reveals a 15-km wide piggyback basin of synorogenic marine clays north of another faulted anticline of Aututu and Cribas on the south coast. The eastern Laclo-Barique transect exposes a deeper erosional level, showing three regional NNE-striking thrust faults with approximately 3 km spacing and 50-75 km along-strike extent, each one repeating the Aitutu and Cribas stratigraphy. The strike of Australian-affinity units in the eastern transect is rotated 50-60 degrees to the north compared to the units in the central transect. The Jurassic Wailuli shales and the Bobonaro tectonic mélange act as the upper décollement between this duplex and the Lolotoi

  14. 76 FR 5189 - BOEMRE Information Collection Activities: 1010-0081, Operations in the Outer Continental Shelf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-28

    ...To comply with the Paperwork Reduction Act of 1995 (PRA), we are notifying the public that we have submitted to OMB an information collection request (ICR) to renew approval of the paperwork requirements in the regulations under 30 CFR 282, Operations in the Outer Continental Shelf for Minerals Other than Oil, Gas, and Sulphur. This notice also provides the public a second opportunity to......

  15. The Continental Plates are Getting Thicker.

    ERIC Educational Resources Information Center

    Kerr, Richard A.

    1986-01-01

    Reviews seismological studies that provide evidence of the existence of continental roots beneath the continents. Suggests, that through the collisions of plate tectonics, continents stabilized part of the mobile mantle rock beneath them to form deep roots. (ML)

  16. Mantle thermal structure and active upwelling during continental breakup in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Holbrook, W. Steven; Larsen, H. C.; Korenaga, J.; Dahl-Jensen, T.; Reid, I. D.; Kelemen, P. B.; Hopper, J. R.; Kent, G. M.; Lizarralde, D.; Bernstein, S.; Detrick, R. S.

    2001-08-01

    Seismic reflection and refraction data acquired on four transects spanning the Southeast Greenland rifted margin and Greenland-Iceland Ridge (GIR) provide new constraints on mantle thermal structure and melting processes during continental breakup in the North Atlantic. Maximum igneous crustal thickness varies along the margin from >30 km in the near-hotspot zone (<500 km from the hotspot track) to ˜18 km in the distal zone (500-1100 km). Magmatic productivity on summed conjugate margins of the North Atlantic decreases through time from 1800±300 to 600±50 km 3/km/Ma in the near-hotspot zone and from 700±200 to 300±50 km 3/km/Ma in the distal zone. Comparison of our data with the British/Faeroe margins shows that both symmetric and asymmetric conjugate volcanic rifted margins exist. Joint consideration of crustal thickness and mean crustal seismic velocity suggests that along-margin changes in magmatism are principally controlled by variations in active upwelling rather than mantle temperature. The thermal anomaly (Δ T) at breakup was modest (˜100-125°C), varied little along the margin, and transient. Data along the GIR indicate that the potential temperature anomaly (125±50°C) and upwelling ratio (˜4 times passive) of the Iceland hotspot have remained roughly constant since 56 Ma. Our results are consistent with a plume-impact model, in which (1) a plume of radius ˜300 km and Δ T of ˜125°C impacted the margin around 61 Ma and delivered warm material to distal portions of the margin; (2) at breakup (56 Ma), the lower half of the plume head continued to feed actively upwelling mantle into the proximal portion of the margin; and (3) by 45 Ma, both the remaining plume head and the distal warm layer were exhausted, with excess magmatism thereafter largely confined to a narrow (<200 km radius) zone immediately above the Iceland plume stem. Alternatively, the warm upper mantle layer that fed excess magmatism in the distal portion of the margin may have been

  17. Observation of Single Pt Nanoparticle Collisions: Enhanced Electrocatalytic Activity on a Pd Ultramicroelectrode.

    PubMed

    Shin, Changhwan; Park, Tae Eun; Park, Changki; Kwon, Seong Jung

    2016-06-01

    Single Pt nanoparticle (NP) collisions on an electrode surface were detected by using an electrocatalytic amplification method with a Pd ultramicroelectrode (UME). Pd is not a preferred material for UMEs for the detection of single Pt NP collisions, because Pd shows similar electrocatalytic activity compared with Pt for hydrazine oxidation, thus resulting in a high background current level. However, a Pt NP colliding on the Pd UME shows greatly enhanced activity compared with a Pt NP on an inert UME, such as a Au UME, which is usually used for the detection of single Pt NP collisions. The use of an electroactive UME material instead of an inert one facilitated the study of single-NP activity on the various solid supports, which is important in many NP applications. PMID:26955784

  18. Erosion-accumulative activity of the bottom currents on the continental rise of Brazil

    NASA Astrophysics Data System (ADS)

    Borisov, D. G.; Murdmaa, I. O.; Ivanova, E. V.; Roslyakov, A. G.; Anan'ev, R. A.

    2013-09-01

    Several high-resolution "SES 2000 deep" seismic profiles and a core of bottom sediments were obtained in cruises 33, 35, and 37 of the R/V Akademik Ioffe in the area of the Columbia channel (continental rise of Brazil, South America). The analysis of seismic facies and direct correlation of acoustic and lithological data indicates that sedimentation in this area is mostly controlled by the contour current of the Antarctic Bottom Water (AABW). The gravity flows from seamounts and continental slope only episodically contributed coarser material to the deposition of the muddy contourites. The mixed gravitite-contourite systems consisting of accumulative bodies (drifts) and erosion channels are the results of interaction of these sedimentation processes.

  19. The Late Paleozoic Southern Margin of the Siberian paleocontinent: transformation from an active continental margin to intracontinental rifting

    NASA Astrophysics Data System (ADS)

    Kozlovsky, A. M.; Yarmolyuk, V. V.; Sal'Nikova, E. B.

    2009-04-01

    The large volcanoplutonic belt was formed on the southern margin of Siberian paleocontinent in the Early Carboniferous-Early Permian. Now it's stretched through whole Mongolia and the adjacent region of China. In the belt structure there are defined the successive rock complexes: the older one represented by differentiated basalt-andesite-rhyodacite series and younger bimodal complex of basalt-comendite-trachyrhyolite composition. The granodiorite-plagiogranite and diorite-monzonite-granodiorite plutonic massifs are associated with the former, while peralkaline granite massifs are characteristic of the latter. Geochronological results and geological relations between rocks of the bimodal and differentiated complexes showed first that rocks of the differentiated complex originated 350 to 330 Ma ago at the initial stage of forming of the marginal continental belt, linked with development active continental margin. This is evident from geochronological dates obtained for the Adzh-Bogd and Edrengiyn-Nuruu massifs and for volcanic associations of the complex. The dates are consistent with paleontological data. The bimodal association was formed later, 320 to 290 Ma ago. The time span separating formation of two igneous complexes ranges from several to 20-30 m.y. in different areas of the marginal belt. The bimodal magmatism was interrelated with rifting responsible for development of the Gobi-Tien Shan rift zone in the belt axial part and the Main Mongolian lineament along the belt northern boundary. Loci of bimodal rift magmatism likely migrated with time: the respective magmatic activity first initiated on the west of the rift system and then advanced gradually eastward with development of rift structures. Normal granitoids untypical but occurring nevertheless among the products of rift magmatism in addition to peralkaline massifs are assumed to have been formed, when the basic magmatism associated with rifting stimulated crustal anatexis and generation of crustal

  20. Why does continental convergence stop

    SciTech Connect

    Hynes, A.

    1985-01-01

    Convergence between India and Asia slowed at 45 Ma when they collided, but continues today. This requires that substantial proportions of the Indian and/or Asian lithospheric mantle are still being subducted. The resulting slab-pull is probably comparable with that from complete lithospheric slabs and may promote continued continental convergence even after collision. Since descending lithospheric slabs are present at all collision zones at the time of collision such continued convergence may be general after continental collisions. It may cease only when there is a major (global) plate reorganization which results in new forces on the convergent continents that may counteract the slab-pull. These inferences may be tested on the late Paleozoic collision between Gondwanaland and Laurasia. This is generally considered to have been complete by mid-Permian time (250 Ma). However, this may be only the time of docking of Gondwanaland with North America, not that of the cessation of convergence. Paleomagnetic polar-wander paths for the Gondwanide continents exhibit consistently greater latitudinal shifts from 250 Ma to 200 Ma than those of Laurasia when corrected for post-Triassic drift, suggesting that convergence continued through late Permian well into the Triassic. It may have been accommodated by crustal thickening under what is now the US Coastal Plain, or by strike-slip faulting. Convergence may have ceased only when Pangea began to fragment again, in which case the cause for its cessation may be related to the cause of continental fragmentation.

  1. Initiation of Extension in South China Continental Margin during the Active-Passive Margin Transition: Thermochronological and Kinematic Constraints

    NASA Astrophysics Data System (ADS)

    Zuo, X.; Chan, L. S.

    2015-12-01

    The South China continental margin is characterized by a widespread magmatic belt, prominent NE-striking faults and numerous rifted basins filled by Cretaceous-Eocene sediments. The geology denotes a transition from active to passive margin, which led to rapid modifications of crustal stress configuration and reactivation of older faults in this area. Our zircon fission-track data in this region show two episodes of exhumation: The first episode, occurring during 170-120Ma, affected local parts of the Nanling Range. The second episode, a more regional exhumation event, occurred during 115-70Ma, including the Yunkai Terrane and the Nanling Range. Numerical geodynamic modeling was conducted to simulate the subduction between the paleo-Pacific plate and the South China Block. The modeling results could explain the fact that exhumation of the granite-dominant Nanling Range occurred earlier than that of the gneiss-dominant Yunkai Terrane. In addition to the difference in rock types, the heat from Jurassic-Early Cretaceous magmatism in Nanling may have softened the upper crust, causing the area to exhume more readily than Yunkai. Numerical modeling results also indicate that (1) high lithospheric geothermal gradient, high slab dip angle and low convergence velocity favor the reversal of crustal stress state from compression to extension in the upper continental plate; (2) late Mesozoic magmatism in South China was probably caused by a slab roll-back; and (3) crustal extension could have occurred prior to the cessation of plate subduction. The inversion of stress regime in the continental crust from compression to crustal extension imply that the Late Cretaceous-early Paleogene red-bed basins in South China could have formed during the late stage of the subduction, accounting for the occurrence of volcanic events in some sedimentary basins. We propose that the rifting started as early as Late Cretaceous, probably before the cessation of subduction process.

  2. Early Jurassic Volcanism in the South Lhasa Terrane, Southern Tibet: Record of Back-arc Extension in the Active Continental Margin

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Zhao, Z.; Zhu, D. C.; Wang, Z.; Liu, D.; Mo, X.

    2015-12-01

    Indus-Yarlung Zangbo Suture Zone (IYZSZ) represents the Mesozoic remnants of the Neo-Tethyan Ocean lithosphere after its northward subduction beneath the Lhasa Terrane. The evolution of the Neo-Tethyan Ocean prior to India-Asia collision remains unclear. To explore this period of history, we investigate zircon U-Pb geochronology, geochemistry and Nd-Hf isotopes of the Early Jurassic bimodal-like volcanic sequence around Dagze area, south Tibet. The volcanic sequence comprises calc-alkaline basalts to rhyolites whereas intermediate components are volumetrically restricted. Zircons from a basaltic andesite yielded crystallization age of 178Ma whereas those from 5 silicic rocks were dated at 183-174Ma, which suggest that both the basaltic and the silicic rocks are coeval. The basaltic rocks are enriched in LREE and LILE, and depleted in HFSE, with Epsilon Nd(t) of 1.6-4.0 and zircon Epsilon Hf(t) of 0.7-11.8, which implies that they were derived from a heterogenetic mantle source metasomatized by subduction components. Trace element geochemistry shows that the basaltic rocks are compositionally transitional from normal mid-ocean ridge basalts (N-MORB) to island arc basalts (IAB, e.g. Zedong arc basalts of ~160-155Ma in the south margin of Lhasa Terrane), with the signature of immature back-arc basin basalts. The silicic rocks display similar Nd-Hf isotopic features of the Gangdese batholith with Epsilon Nd(t) of 0.9-3.4 and zircon Epsilon Hf(t) of 2.4-17.7, indicating that they were possibly generated by anatexis of basaltic juvenile lower crust, instead of derived from the basaltic magma. These results support an Early to Middle Jurassic (183-155Ma) model that the back-arc extension tectonic setting were existing in the active continental margin in the south Lhasa Terrane.

  3. Application of Global Positioning Measurements to Continental Collision in the Pamir-Tien Shan Region, Central Asia and GPS Survey of the Western Tien Shan

    NASA Technical Reports Server (NTRS)

    Hamburger, Michael W.; Reilinger, Robert E.; Hager, Bradford H.; Molnar, Peter

    1997-01-01

    In this report, we summarize what we have accomplished with five years of funding from NASA under its DOSE program, and with a comparable level of funding from NSF. We describe the development of a GPS network in the Tien Shan of Kyrgyzstan and Kazakhstan of the former Soviet Union, the analysis of data, and the main results. This discussion presents the state of the current network, which has grown significantly since the termination of our DOSE grants, with continued support both from NSF through its continental dynamics program and from NASA's SENH program. Although grants from NASA's DOSE program did not support this growth not directly, it did so indirectly by building the infrastructure that has enabled further expansion in an area where otherwise there would be only a small GPS presence. We note how the network has grown over time, but the emphasis of this discussion is on the quantity and quality of measurements that we have made.

  4. High-resolution seismic stratigraphy of the late Neogene of the central sector of the Colombian Pacific continental shelf: A seismic expression of an active continental margin

    NASA Astrophysics Data System (ADS)

    Martínez, Jaime Orlando; López Ramos, Eduardo

    2011-02-01

    The sedimentary prism of the central Pacific continental shelf of Colombia was affected by regional folding and faulting, and probably later mud diapirism, from the Late Miocene to the Holocene. Interpretation of high-resolution seismic lines (2 s/dt) revealed that the prism consists of 13 high-resolution seismic units, that can be separated into 5 seismic groups. Deposition of the prism and the associated stacking pattern, are probably the response to variable uplift and subsidence in a fore-arc basin that underwent important tectonic events by the end of the Miocene. Throughout the Pliocene, the continental shelf sedimentation was affected by the growing of a dome structure probable due to mud diapirism. This fact caused peripheral faults both normal and reverse that controlled the distribution of some of the seismic units. During the Late Pleistocene (Wisconsin stage?) a eustatic sea level fall caused the shoreline to advance about 50 km westward of its present position. Because of this eustatic sea level change, a strong fluvial dissection took place and is interpreted as the probable extension of the San Juan River to the south of the present day river mouth. Within this framework it is believed that the Malaga and Buenaventura Bays were the passageways of branches of the old drainage system of the San Juan River. The inner branch circulated through the present Buenaventura Bay and runs southward leaving the mark of an apparent valley identified in the seismic information in the eastern sector of the study area. This old fluvial valley and its filling material located in the present day inner continental shelf front of Buenaventura are postulated as important targets to find placer minerals such as gold and platinum.

  5. Three-dimensional electrical resistivity image of magma beneath an active continental rift, Taupo Volcanic Zone, New Zealand

    NASA Astrophysics Data System (ADS)

    Heise, Wiebke; Caldwell, T. Grant; Bibby, Hugh M.; Bennie, Stewart L.

    2010-05-01

    Magmatic activity in regions of continental extension may result in huge (>400 km3) explosive eruptions of viscous, gas-rich silicic-magma. Geochemical and geological data suggest that the large volumes of magma erupted are produced by extracting interstitial liquid from a long-lived ‘mush zone’ (a mixture of solid crystals and liquid melt) that accumulates in liquid-dominated lenses at the top of a much thicker region of lower melt-fraction mush. Such lenses will be highly electrically conductive compared with normal mid-crustal rocks. Here we use results of 220 magnetotelluric (MT) soundings to construct a 3-D electrical resistivity image of the northern (silicic) part of New Zealand's Taupo Volcanic Zone, a young continental rift associated with very high heat flow and intense silicic volcanism. The electrical resistivity image shows a plume-like structure of high conductivity, interpreted to be a zone of interconnected melt, rising from depths >35 km beneath the axis of extension.

  6. Hanging canyons of Haida Gwaii, British Columbia, Canada: Fault-control on submarine canyon geomorphology along active continental margins

    NASA Astrophysics Data System (ADS)

    Harris, Peter T.; Barrie, J. Vaughn; Conway, Kim W.; Greene, H. Gary

    2014-06-01

    Faulting commonly influences the geomorphology of submarine canyons that occur on active continental margins. Here, we examine the geomorphology of canyons located on the continental margin off Haida Gwaii, British Columbia, that are truncated on the mid-slope (1200-1400 m water depth) by the Queen Charlotte Fault Zone (QCFZ). The QCFZ is an oblique strike-slip fault zone that has rates of lateral motion of around 50-60 mm/yr and a small convergent component equal to about 3 mm/yr. Slow subduction along the Cascadia Subduction Zone has accreted a prism of marine sediment against the lower slope (1500-3500 m water depth), forming the Queen Charlotte Terrace, which blocks the mouths of submarine canyons formed on the upper slope (200-1400 m water depth). Consequently, canyons along this margin are short (4-8 km in length), closely spaced (around 800 m), and terminate uniformly along the 1400 m isobath, coinciding with the primary fault trend of the QCFZ. Vertical displacement along the fault has resulted in hanging canyons occurring locally. The Haida Gwaii canyons are compared and contrasted with the Sur Canyon system, located to the south of Monterey Bay, California, on a transform margin, which is not blocked by any accretionary prism, and where canyons thus extend to 4000 m depth, across the full breadth of the slope.

  7. Crustal differentiation due to partial melting of granitic rocks in an active continental margin, the Ryoke Belt, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Akasaki, Eri; Owada, Masaaki; Kamei, Atsushi

    2015-08-01

    The continental margin of Pacific Asia is dominated by the voluminous Cretaceous to Paleogene granitic rocks. The Ryoke granitoids that occur in the Ryoke Belt in the Southwest Japan Arc are divided into the older and younger granites. The high-K Kibe Granite represents the younger granitic intrusion and is exposed in the Yanai area in the western part of Ryoke Belt. The Kibe Granite is associated with the coeval Himurodake Quartz Diorite and their intrusive age is 91 Ma. However, the Gamano-Obatake Granodiorite, the older granite, intruded the host Ryoke gneisses at 95 Ma. The Gamano-Obatake Granodiorite is characterized by the localized development of migmatitic structure attributed to the intrusion of the Himurodake Quartz Diorite into the granodiorite. Leucocratic pools and patches occur in the granodiorite in the vicinity of the quartz diorite. The Sr and Nd isotopic compositions of the Gamano-Obatake Granodiorite corrected to 91 Ma are plotted within those of the Kibe Granite. Geochemical modeling suggests that partial melting took place in the Gamano-Obatake Granodiorite and resulted in the formation of the Kibe Granite magma. The Himurodake Quartz Diorite is believed to be a heat source for this event. This can be considered as an essential process for the formation of the evolved younger Ryoke granite and for the crustal differentiation in the active continental margin.

  8. Geochemical and Sr-Nd-Hf isotopic constraints on the origin of Late Triassic granitoids from the Qinling orogen, central China: Implications for a continental arc to continent-continent collision

    NASA Astrophysics Data System (ADS)

    Jiang, Yao-Hui; Jin, Guo-Dong; Liao, Shi-Yong; Zhou, Qing; Zhao, Peng

    2010-06-01

    The Qinling-Dabie-Sulu orogen marks the junction between the North and South China Blocks. However, the exact timing of the final coalescence of the North and South China Blocks in the Qinling orogen is poorly constrained. This paper presents new SHRIMP zircon U-Pb chronology, major and trace elements, and Sr-Nd-Hf isotope data for five early Mesozoic granitic plutons across the Qinling orogen. SHRIMP zircon U-Pb dating shows that four plutons were emplaced in the Carnian (227-218 Ma) of Late Triassic with a southward-younging trend and one pluton was emplaced in the Norian (˜ 211 Ma) of Late Triassic. The Carnian plutons consist of high-K calc-alkaline granitoids (quartz monzodiorite, quartz monzonite, granodiorite and monzogranite) and calc-alkaline diorite. These rocks are mainly metaluminous and are characterized by high Sr and low Y and Yb contents, with high Sr/Y and La/Yb ratios, and by high Mg#, higher than pure crustal melts. The Norian pluton is composed of high-K calc-alkaline two-mica granites, which are peraluminous. These granites have low Sr and high Y and Yb contents and show similar Mg# to pure crustal melts. Detailed elemental and isotopic data suggest that the Carnian plutons were emplaced in a continental arc setting coupled with the northward subduction of the Paleo-Tethyan oceanic crust. Partial melting of subducted sediments triggered by dehydration of the underlying igneous oceanic crust, with subsequent melts interacting with the overlying mantle wedge, formed the high-K calc-alkaline granitic magmas. Partial melting of the hybridized peridotitic mantle wedge induced by slab melts generated the calc-alkaline dioritic magma. The Norian pluton was emplaced during continental collision between the South Qinling terrane and South China Block, which marks the final integration of the North and South China Blocks. Partial melting of subducted sediments at a shallow depth (< 30 km) in the collision (overthrust) zone could account for the origin

  9. Lena Trough (Arctic Ocean): Active mantle exhumation on a continental rifted margin

    NASA Astrophysics Data System (ADS)

    Snow, J. E.; Hellebrand, E.; von der Handt, A.; Nauret, F.

    2004-12-01

    Lena Trough is the northern continuation of the Mid-Atlantic Ridge through Fram Strait and into the Arctic Ocean. The rifting of Lena Trough began in the Miocene, and significantly, is the final and the most recent event in the separation of the North American from the Eurasian continent. Lena Trough was mapped in 1999, 2001 and 2004 by PFS Polarstern (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany), revealing sea floor structures that are inconsistent with any normally conceived mid-ocean ridge spreading, and instead indicative of late continental rifting. Lena Trough is shown to be a deep, fault-bounded basin with depths of 3800-4200m, and irregular, steep valley sides that are oblique to the spreading direction. Basement horst structures that outcrop as sigmoidal ridges with steeply dipping sides project out of the valley floor. These basement ridges are roughly parallel along flow lines to the valley walls on either side. Ridge-orthogonal topography is simply absent (ie no segments trending parallel nor fracture zones perpendicular to Gakkel Ridge). Most faults trend approximately SSE-NNW, an obliquity with respect to Gakkel Ridge (SW-NE) of about 55°. The basement ridges are composed nearly entirely of fertile mantle peridotite, as are the valley walls. Only at the northern and southern extremities of Lena Trough do basalts appear at all. The peridotites compositions are consistent with either continental or oceanic (asthenospheric) mantle. They show evidence of low-degree mantle melting, followed by high-level stagnation in a thick lithosphere. This evidence (veining, impregnation) is more evident where little or no basaltic cover is present, while peridotites dredged in the vicinity of basalts tend to be more residual. This may indicate some degree of magmatic focusing in the absence of a basaltic crust per se. Lena Trough contains rare, highly alkaline basalts that are unlike any compositions dredged from mid-ocean ridges

  10. Lena Trough (Arctic Ocean): Active mantle exhumation on a continental rifted margin

    NASA Astrophysics Data System (ADS)

    Snow, J. E.; Hellebrand, E.; von der Handt, A.; Nauret, F.

    2007-12-01

    Lena Trough is the northern continuation of the Mid-Atlantic Ridge through Fram Strait and into the Arctic Ocean. The rifting of Lena Trough began in the Miocene, and significantly, is the final and the most recent event in the separation of the North American from the Eurasian continent. Lena Trough was mapped in 1999, 2001 and 2004 by PFS Polarstern (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany), revealing sea floor structures that are inconsistent with any normally conceived mid-ocean ridge spreading, and instead indicative of late continental rifting. Lena Trough is shown to be a deep, fault-bounded basin with depths of 3800-4200m, and irregular, steep valley sides that are oblique to the spreading direction. Basement horst structures that outcrop as sigmoidal ridges with steeply dipping sides project out of the valley floor. These basement ridges are roughly parallel along flow lines to the valley walls on either side. Ridge-orthogonal topography is simply absent (ie no segments trending parallel nor fracture zones perpendicular to Gakkel Ridge). Most faults trend approximately SSE-NNW, an obliquity with respect to Gakkel Ridge (SW-NE) of about 55°. The basement ridges are composed nearly entirely of fertile mantle peridotite, as are the valley walls. Only at the northern and southern extremities of Lena Trough do basalts appear at all. The peridotites compositions are consistent with either continental or oceanic (asthenospheric) mantle. They show evidence of low-degree mantle melting, followed by high-level stagnation in a thick lithosphere. This evidence (veining, impregnation) is more evident where little or no basaltic cover is present, while peridotites dredged in the vicinity of basalts tend to be more residual. This may indicate some degree of magmatic focusing in the absence of a basaltic crust per se. Lena Trough contains rare, highly alkaline basalts that are unlike any compositions dredged from mid-ocean ridges

  11. Active-sterile neutrino oscillations in the early Universe with full collision terms

    SciTech Connect

    Hannestad, Steen; Hansen, Rasmus Sloth; Tram, Thomas; Wong, Yvonne Y.Y.

    2015-08-11

    Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution of the neutrino phase space distributions. Until now the collision terms in the quantum kinetic equations have always been approximated using equilibrium distributions, but this approximation has never been checked numerically. In this work we revisit the sterile neutrino thermalisation calculation using the full collision term, and compare the results with various existing approximations in the literature. We find a better agreement than would naively be expected, but also identify some issues with these approximations that have not been appreciated previously. These include an unphysical production of neutrinos via scattering and the importance of redistributing momentum through scattering, as well as details of Pauli blocking. Finally, we devise a new approximation scheme, which improves upon some of the shortcomings of previous schemes.

  12. Active-sterile neutrino oscillations in the early Universe with full collision terms

    NASA Astrophysics Data System (ADS)

    Hannestad, Steen; Sloth Hansen, Rasmus; Tram, Thomas; Wong, Yvonne Y. Y.

    2015-08-01

    Sterile neutrinos are thermalised in the early Universe via oscillations with the active neutrinos for certain mixing parameters. The most detailed calculation of this thermalisation process involves the solution of the momentum-dependent quantum kinetic equations, which track the evolution of the neutrino phase space distributions. Until now the collision terms in the quantum kinetic equations have always been approximated using equilibrium distributions, but this approximation has never been checked numerically. In this work we revisit the sterile neutrino thermalisation calculation using the full collision term, and compare the results with various existing approximations in the literature. We find a better agreement than would naively be expected, but also identify some issues with these approximations that have not been appreciated previously. These include an unphysical production of neutrinos via scattering and the importance of redistributing momentum through scattering, as well as details of Pauli blocking. Finally, we devise a new approximation scheme, which improves upon some of the shortcomings of previous schemes.

  13. Mid to late Holocene aeolian activity revealed by a multiproxy peat record in continental CE Europe (Northern Romania)

    NASA Astrophysics Data System (ADS)

    Panait, Andrei Marian; Feurdean, Angelica; Hutchinson, Simon Mark; Tanţǎu, Ioan

    2016-04-01

    Peat bogs, and especially ombrogenous mire, are increasingly used as continental archives of aeolian dust and sand deposition. Since ombrogenous peat is formed above ground water level all the inputs are atmospheric. Dust is more influenced by regional climatic patterns due to its small size, whereas sand tends to record local patterns in storm frequency and intensity reflecting its larger particle size. However, both size fractions are significantly underused proxies of past climate variability. Here, an ombrogenous peat profile from Tǎul Muced in the Rodnei Mountains (Northern Romanian Carpathians), located in a temperate continental climate, with Atlantic and Baltic influences, provides the very first record of mid to late Holocene aeolian activity from Romania highlighting the interplay between local and regional controls in a continental area of CE Europe. We use a multiproxy approach combining radiocarbon dating, the physical properties of the peat (loss-on-ignition, bulk density), mineral magnetic measurements (ARM, SIRM), geochemical (Ti and Zr) and particle size analysis (via both laser diffraction and the manual counting of sand particles under a steromicroscope) to determine changes in: i) atmospheric dust deposition and ii) wind velocities during the last 7800 years. We found that the aeolian particles are mainly silt (3.9-63 μm) (dust) and sand (63-1200 μm). The mineralogical composition of the aeolian sediment in peat is mainly quartz, more rarely calcite and very rarely other minerals such as feldspar, sulphur, mica (biotite and muscovite), magnetite and other melanocrate minerals. The roundness of the sand particles varies from well-rounded to sub-angular and angular, and suggests that the sand particles have different source areas. Results from this study show that over the last 7600 years the pattern of wind frequency changed several times: there are periods characterised by a low aeolian input around 6950-6550, 5000-3900, 3500-2900, 1650

  14. Zircon U-Pb And Biotite 40Ar/39Ar Ages Of Kohistan Lower Crustal Tonalite And Their Implications For The History Of Continental Collision

    NASA Astrophysics Data System (ADS)

    Nakajima, T.; Williams, I. S.; Hyodo, H.; Miyazaki, K.; Sano, S.; Kausar, A. B.

    2002-12-01

    The Kohistan block in northern Pakistan exposes a crustal cross section through an ancient oceanic island arc, comprising garnet pyroxenite, garnet granulite, banded amphibolite, norite gabbro, metasediment and metavolcanics. The Dasu Tonalite intrudes the lower crustal Kamila Amphibolite. The tonalite is foliated and folded concordantly with the host amphibolite, indicating syn-tectonic intrusion, and contains abundant magmatic epidotes, indicating high-P crystallization. The Dasu Tonalite is extremely poor in K2O (0.6-0.9 wt.% for SiO2 64-70%) and has a low initial 87Sr/86Sr (0.7037-0.7038, similar to the associated lower crustal amphibolite and granulite), consistent with juvenile granitic magma free of contamination by recycled upper crust. The Dasu Tonalite gave SHRIMP zircon U-Pb ages of 97.6+/-1.0 Ma and 98.0+/-1.1 Ma on two samples, and biotite 40Ar/39Ar ages of 69.7+/-0.7 Ma and 69.7+/-0.9 Ma. The euhedral shape and lack of overgrowth or resorption features in CL images of the zircons suggest a simple magmatic history starting at ca. 98 Ma with no evidence for a later major thermal event. The large discrepancy between the U-Pb and Ar-Ar ages might record the deep crustal residence time of the Dasu Tonalite. The tonalite magma was probably generated and crystallized at ca. 98 Ma, then remained in the lower crust at a temperature of about 700C (which is given by geothermometry of the intercalating Kamila amphibolite), cooling down to ca.300C at 69.7Ma. 69.7Ma is a cooling age during the process of exhumation of the Kohistan arc caused by the Indian collision.

  15. 77 FR 5039 - Accommodation Service Provided on Vessels Engaged in U.S. Outer Continental Shelf Activities

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ... SECURITY Coast Guard Accommodation Service Provided on Vessels Engaged in U.S. Outer Continental Shelf... providing accommodation service on the U.S. Outer Continental Shelf. DATES: Comments and related material... Act notice regarding our public dockets in the January 17, 2008, issue of the Federal Register (73...

  16. Evolution and stability of shock waves in dissipative gases characterized by activated inelastic collisions.

    PubMed

    Sirmas, N; Radulescu, M I

    2015-02-01

    Previous experiments have revealed that shock waves driven through dissipative gases may become unstable, for example, in granular gases and in molecular gases undergoing strong relaxation effects. The mechanisms controlling these instabilities are not well understood. We successfully isolated and investigated this instability in the canonical problem of piston-driven shock waves propagating into a medium characterized by inelastic collision processes. We treat the standard model of granular gases, where particle collisions are taken as inelastic, with a constant coefficient of restitution. The inelasticity is activated for sufficiently strong collisions. Molecular dynamic simulations were performed for 30,000 particles. We find that all shock waves investigated become unstable, with density nonuniformities forming in the relaxation region. The wavelength of these fingers is found to be comparable to the characteristic relaxation thickness. Shock Hugoniot curves for both elastic and inelastic collisions were obtained analytically and numerically. Analysis of these curves indicates that the instability is not of the Bethe-Zeldovich-Thompson or D'yakov-Kontorovich type. Analysis of the shock relaxation rates and rates for clustering in a convected fluid element with the same thermodynamic history ruled out the clustering instability of a homogeneous granular gas. Instead, wave reconstruction of the early transient evolution indicates that the onset of instability occurs during repressurization of the gas following the initial relaxation of the medium behind the lead shock. This repressurization gives rise to internal pressure waves in the presence of strong density gradients. This indicates that the mechanism of instability is more likely of the vorticity-generating Richtmyer-Meshkov type, relying on the action of the inner pressure wave development during the transient relaxation. PMID:25768593

  17. 78 FR 8190 - Commercial Wind Leasing and Site Assessment Activities on the Atlantic Outer Continental Shelf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-05

    ...BOEM is reopening the comment period announced in the Notice of Intent to Prepare an Environmental Assessment (EA) for Commercial Wind Leasing and Site Assessment Activities on the OCS Offshore North...

  18. Age, composition, and source of continental arc- and syn-collision granites of the Neoproterozoic Sergipano Belt, Southern Borborema Province, Brazil

    NASA Astrophysics Data System (ADS)

    Oliveira, Elson P.; Bueno, Juliana F.; McNaughton, Neal J.; Silva Filho, Adejardo F.; Nascimento, Rosemery S.; Donatti-Filho, José P.

    2015-03-01

    The Sergipano belt is the outcome of collision between the Pernambuco-Alagoas Domain (Massif) and the São Francisco Craton during Neoproterozoic assembly of West Gondwana. Although the understanding of the Sergipano belt evolution has improved significantly, the timing of emplacement, geochemistry and tectonic setting of granitic bodies in the belt is poorly known. We recognized two granite age groups: 630-618 Ma granites in the Canindé, Poço Redondo and Macururé domains, and 590-570 Ma granites in the Macururé metasedimentary domain. U-Pb SHRIMP zircon ages for granites of first age group indicated ages of 631 ± 4 Ma for the Sítios Novos granite, 623 ± 7 Ma for the Poço Redondo granite, 619 ± 3.3 Ma for the Lajedinho monzodiorite, and 618 ± 3 Ma for the Queimada Grande granodiorite. These granitoids are dominantly high-K calc-alkaline, magnesian, metaluminous, mafic enclave-rich (Queimada Grande and Lajedinho), or with abundant inherited zircon grains (Poço Redondo and Sitios Novos). Geochemical and isotope data allow us to propose that Sítios Novos and Poço Redondo granites are product of partial melting of Poço Redondo migmatites. Sr-Nd isotopes of the Queimada Grande granodiorite and Lajedinho monzodiorite suggest that their parental magma may have originated by mixing between a juvenile mafic source and a crustal component that could be the Poço Redondo migmatites or the Macururé metasediments. Other 630-618 Ma granites in the belt are the mafic enclave-rich Coronel João Sá granodiorite and the Camará tonalite in the Macururé sedimentary domain. These granites have similar geochemical and isotopic characteristics as the Lajedinho and Queimada Grande granitoids. We infer for the Camará tonalite and Coronel João Sá granodiorite that their parental magmas have had contributions from mafic lower crust and felsic upper crust, most probably from underthrust São Francisco Craton, or Pernambuco-Alagoas Domain. The younger 590-570 Ma granite

  19. Measurement of inter- and intra-annual variability of landscape fire activity at a continental scale: the Australian case

    NASA Astrophysics Data System (ADS)

    Williamson, Grant J.; Prior, Lynda D.; Jolly, W. Matt; Cochrane, Mark A.; Murphy, Brett P.; Bowman, David M. J. S.

    2016-03-01

    Climate dynamics at diurnal, seasonal and inter-annual scales shape global fire activity, although difficulties of assembling reliable fire and meteorological data with sufficient spatio-temporal resolution have frustrated quantification of this variability. Using Australia as a case study, we combine data from 4760 meteorological stations with 12 years of satellite-derived active fire detections to determine day and night time fire activity, fire season start and end dates, and inter-annual variability, across 61 objectively defined climate regions in three climate zones (monsoon tropics, arid and temperate). We show that geographic patterns of landscape burning (onset and duration) are related to fire weather, resulting in a latitudinal gradient from the monsoon tropics in winter, through the arid zone in all seasons except winter, and then to the temperate zone in summer and autumn. Peak fire activity precedes maximum lightning activity by several months in all regions, signalling the importance of human ignitions in shaping fire seasons. We determined median daily McArthur forest fire danger index (FFDI50) for days and nights when fires were detected: FFDI50 varied substantially between climate zones, reflecting effects of fire management in the temperate zone, fuel limitation in the arid zone and abundance of flammable grasses in the monsoon tropical zone. We found correlations between the proportion of days when FFDI exceeds FFDI50 and the Southern Oscillation index across the arid zone during spring and summer, and Indian Ocean dipole mode index across south-eastern Australia during summer. Our study demonstrates that Australia has a long fire weather season with high inter-annual variability relative to all other continents, making it difficult to detect long term trends. It also provides a way of establishing robust baselines to track changes to fire seasons, and supports a previous conceptual model highlighting multi-temporal scale effects of climate in

  20. 77 FR 5830 - Commercial Wind Leasing and Site Assessment Activities on the Atlantic Outer Continental Shelf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-06

    ... FR 30,616) of the EA for Issuance of Leases for Wind Resource Data Collection on the Outer... (NOA) in the Federal Register (72 FR 62,672) of the Programmatic EIS for Alternative Energy Development... Bureau of Ocean Energy Management Commercial Wind Leasing and Site Assessment Activities on the...

  1. 78 FR 33908 - Commercial Wind Lease Issuance and Site Assessment Activities on the Atlantic Outer Continental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... identified Wind Energy Area (WEA) on the OCS offshore Rhode Island (RI) and Massachusetts (MA). The revised... from leasing, site characterization, and site assessment in and around the Call Area (76 FR 51391). The... Bureau of Ocean Energy Management Commercial Wind Lease Issuance and Site Assessment Activities on...

  2. 77 FR 39508 - Commercial Wind Lease Issuance and Site Assessment Activities on the Atlantic Outer Continental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... specific project proposals on those leases) in an identified Wind Energy Area (WEA) on the OCS offshore..., site characterization, and site assessment in and around the Call Area (76 FR 51391). The Call Area is... Bureau of Ocean Energy Management Commercial Wind Lease Issuance and Site Assessment Activities on...

  3. Ice nucleation active particles in continental air samples over Mainz, Germany

    NASA Astrophysics Data System (ADS)

    Pummer, Bernhard G.; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

    2016-04-01

    Aerosol particles are of central importance for atmospheric chemistry and physics, climate and public health. Some of these particles possess ice nucleation activity (INA), which is highly relevant for cloud formation and precipitation. In 2010, air filter samples were collected with a high-volume filter sampler separating fine and coarse particles (aerodynamic cut-off diameter 3 μm) in Mainz, Germany. In this study, the INA of the atmospheric particles deposited on these filters was determined. Therefore,they were extracted with ultrapure water, which was then measured in a droplet freezing assay, as described in Fröhlich-Nowoisky et al. (2015). The determined concentration of ice nucleators (INs) was between 0.3 and 2per m³ at 266 K, and between5 and 75 per m³ at 260 K. The INs were further characterized by different treatments, like heating (308 K, 371 K), filtration (0.1 μm, 300 kDa), and digestion with papain (10 mg/ml). We further investigated, which atmospheric conditions (e.g. weather) and distinguished events (e.g. dust storms, volcanic eruptions, and pollen peaks) influenced the number and nature of these INs. Fröhlich-Nowoisky, J., Hill, T. C. J., Pummer, B. G., Yordanova, P., Franc, G. D., and Pöschl, U.: Ice nucleation activity in the widespread soil fungus Mortierella alpina, Biogeosci., 12, 1057-1071, doi:10.5194/bg-12-1057-2015, 2015.

  4. Dynamics of Continental Accretion

    NASA Astrophysics Data System (ADS)

    Moresi, L. N.; Betts, P. G.; Miller, M. S.

    2013-12-01

    Subduction zones become congested when they try to swallow buoyant exotic crust. Accretionary mountain belts (orogens) that form at these convergent plate margins are the principal sites of lateral continental growth through Earth's history. Modern examples of accretionary margins are the North and South American Cordilleras and southwest Pacific. The geologic record is riddled with accretionary orogens, such as the Tasmanides along the eastern margin of the supercontinent Gondwana and the Altaides that formed on the southern margin of Laurasia. Both the modern and ancient examples are characterised by episodic switches between extension and shortening associated with transitions from collision of exotic crust and subduction related rollback. We present three-dimensional dynamic models that show for the first time how accretionary margins evolve from the initial collision, through a period of plate margin instability, to re-establishment of a stable convergent margin. The models illustrate how significant curvature of the orogenic system develops, as well as the mechanism for tectonic escape of the back arc region. The complexity of the morphology and evolution of the system are driven by lateral rollback of a tightly arcuate trench migrating parallel to the plate boundary and orthogonal to the convergence direction. We find geological and geophysical evidence for this process in the Tasmanides of eastern Australia, but infer that this is a global phenomena throughout Earth's evolution.

  5. Sedimentology of seismo-turbidites off the Cascadia and northern California active tectonic continental margins, Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Gutierrez Pastor, Julia; Nelson, Hans; Goldfinger, Chris; Escutia, Carlota

    2013-04-01

    Holocene turbidites from turbidite channel systems along the active tectonic continental margins of the Cascadia subduction zone (offshore Vancouver Island to Mendocino Triple Junction) and the northern San Andreas Transform Fault (the Triple Junction to San Francisco Bay), have been analyzed for sedimentologic features related to their seismic origin. Centimeter thick silt/sand beds (turbidite base) capped by mud layers (turbidite tail) and interbedded with hemipelagic silty clay intervals with high biogenic content have been characterized by visual core descriptions, grain-size analysis, X-ray radiographs and physical properties. Along the northern California margin in upstream single tributary canyons and channels, most turbidites are uni-pulsed (classic fining up) whereas downstream below multiple tributary canyon and channel confluences, most deposits are stacked turbidites. Because each set of stacked turbidites has no hemipelagic sediment between each turbidite unit and each unit has a distinct mineralogy from a different tributary canyon, we interpret that a stacked turbidite is deposited by several coeval turbidity currents fed by multiple tributary canyons and channels with synchronous triggering from a single San Andreas Fault earthquake. The Cascadia margin is characterized by individual multi-pulsed turbidites that contain multiple coarse-grained sub-units without hemipelagic sediment between pulses. Because the number and character of multiple coarse-grained pulses for each correlative multi-pulsed turbidite is almost always constant both upstream and downstream in different channel systems for 600 km along the margin,we interpret that the earthquake shaking or aftershock signature is usually preserved, for the much stronger Cascadia (≥9 Mw) compared to weaker California (≥8Mw) earthquakes, which result in upstream uni-pulsed turbidites and downstream stacked turbidites. Consequently, both the strongest (≥9 Mw) great earthquakes and downstream

  6. Continental Rifts

    NASA Astrophysics Data System (ADS)

    Rosendahl, B. R.

    Continental Rifts, edited by A. M. Quennell, is a new member of the Benchmark Papers in Geology Series, edited in toto by R. W. Fairbridge. In this series the individual volume editors peruse the literature on a given topic, select a few dozen papers of ostensibly benchmark quality, and then reorder them in some sensible fashion. Some of the original papers are republished intact, but many are chopped into “McNuggets™” of information. Depending upon the volume editor, the chopping process can range from a butchering job to careful and prudent pruning. The collecting, sifting, and reorganizing tasks are, of course, equally editor-sensitive. The end product of this series is something akin to a set of Reader's Digest of Geology.

  7. Conventional gas resources of the Gulf of Mexico Outer Continental Shelf - past experience, current activities, future potential

    SciTech Connect

    Lore, G.L. )

    1993-01-01

    Original recoverable proved reserves of hydrocarbons in the 819 fields discovered through 1991 on the Gulf of Mexico Outer Continental Shelf (GOM OCS) are estimated to be 10.74 billion barrels of oil (Bbo) and 130.5 trillion cubic feet of natural gas (Tcfg). Eighty-one of these fields have been depleted and abandoned. Remaining reserves recoverable from the 738 active fields have been estimated to be 2.33 Bbo and 32.0 Tcfg. An additional 70 active fields have not been sufficiently developed to warrant consideration as proved. The GOM OCS is primarily a gas-prone province. Of the 819 proved fields, 676 are classified as gas fields. Cumulative production through 1991 was 8.41 Bbo and 98.5 Tcfg. On an energy-equivalent basis this production equates to nearly 68 percent natural gas. In recent years the area has contributed about 10 percent of the Nation's total domestic oil production and 22 to 25 percent of the gas. Even though three-quarters of the estimated original recoverable proved gas reserves have been produced, the GOM OCS, as the Nation's premier natural-gas-producing province, will continue to have a pivotal role in determining our future gas supply. Historically, oil and gas exploration and development have gradually progressed seaward into the deeper waters of the Gulf of Mexico. The average size of fields discovered has decreased steadily over time, and the exploration effort required for each incremental reserve addition has increased. Assessments of potential undiscovered, economically recoverable conventional hydrocarbon resources on the GOM OCS are highly sensitive to assumptions concerning future cost-price relationships. These assessments suggest that as much gas may still be undiscovered as has already been discovered on the GOM OCS. 13 refs., 6 figs., 3 tabs.

  8. Active layer thermal monitoring of a Dry Valley of the Ellsworth Mountains, Continental Antarctica

    NASA Astrophysics Data System (ADS)

    Schaefer, Carlos Ernesto; Michel, Roberto; Souza, Karoline; Senra, Eduardo; Bremer, Ulisses

    2015-04-01

    The Ellsworth Mountains occur along the southern edge of the Ronne-Filchner Ice Shelf and are subdivided by the Minnesota Glacier into the Heritage Range to the east and the Sentinel Range to the West. The climate of the Ellsworth Mountains is strongly controlled by proximity to the Ronne-Filchner Ice Shelf and elevation. The mean annual air temperature at the 1,000 m level is estimated to be -25°C, and the average annual accumulation of water-equivalent precipitation likely ranges from 150 to 175 mm yr-1 (Weyant, 1966). The entire area is underlain by continuous permafrost of unknown thickness. Based on data collected from 22 pits, 41% of the sites contained dry permafrost below 70 cm, 27% had ice-cemented permafrost within 70 cm of the surface, 27% had bedrock within 70 cm, and 5% contained an ice-core (Bockheim, unpublished; Schaefer et al., 2015). Dry-frozen permafrost, which may be unique to Antarctica, appears to form from sublimation of moisture in ice-cemented permafrost over time. Active-layer depths in drift sheets of the Ellsworth Mountains range from 15 to 50 cm (Bockheim, unpublished); our understanding of Antarctic permafrost is poor, especially at the continent. The active layer monitoring sites were installed at Edson Hills, Ellsworth_Mountains, in the summer of 2012, and consist of thermistors (accuracy ± 0.2 °C) installed at 1 m above ground for air temperature measurements at two soil profiles on quartzite drift deposits, arranged in a vertical array (Lithic Haplorthel 886 m asl, 5 cm, 10 cm, 30 cm and Lithic Anyorthel 850 m asl, 5 cm, 10 cm, 30 cm). All probes were connected to a Campbell Scientific CR 1000 data logger recording data at hourly intervals from January 2nd 2012 until December 29th 2013. We calculated the thawing days (TD), freezing days (FD); isothermal days (ID), freeze thaw days (FTD), thawing degree days (TDD) and freezing degree days (FDD); all according to Guglielmin et al. (2008). Temperature at 5 cm reaches a maximum

  9. Submarine weathering of silicate minerals and the extent of pore water freshening at active continental margins

    NASA Astrophysics Data System (ADS)

    Scholz, Florian; Hensen, Christian; Schmidt, Mark; Geersen, Jacob

    2013-01-01

    studies at active margins (e.g. Aleutians, Cascadia, Nankai Trough) and despite ubiquitous evidence for smectite formation, little evidence for seafloor seepage of dehydration fluids could be found off Central Chile. We argue that the circular process of pore water uptake during smectite formation and release upon illitization implies a balanced freshwater budget and therefore a rather limited potential for net pore water freshening on a margin-wide scale. According to this rationale, pore water freshening at seafloor seeps preferentially occurs at lower latitudes (Central America, Barbados, Mediterranean Ridge) where terrestrial weathering is more intense thus leading to external (i.e. detrital) smectite and thus freshwater inputs to the subduction system.

  10. Remote Maneuver of Space Debris Using Photon Pressure for Active Collision Avoidance

    NASA Astrophysics Data System (ADS)

    Smith, C.

    2014-09-01

    The Space Environment Research Corporation (SERC) is a consortium of companies and research institutions that have joined together to pursue research and development of technologies and capabilities that will help to preserve the orbital space environment. The consortium includes, Electro Optics Systems (Australia), Lockheed Martin Australia, Optus Satellite Systems (Australia), The Australian national University, RMIT University, National Institute of Information and Communications Technology (NICT, Japan) as well as affiliates from NASA Ames and ESA. SERC is also the recipient of and Australian Government Cooperative Research Centre grant. SERC will pursue a wide ranging research program including technologies to improve tracking capability and capacity, orbit determination and propagation algorithms, conjunction analysis and collision avoidance. All of these technologies will contribute to the flagship program to demonstrate active collision avoidance using photon pressure to provide remote maneuver of space debris. This project joins of the proposed NASA Lightforce concept with infrastructure and capabilities provided by SERC. This paper will describe the proposed research and development program to provide an on-orbit demonstration within the next five years for remote maneuver of space debris.

  11. Repeated large-magnitude earthquakes in a tectonically active, low-strain continental interior: The northern Tien Shan, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Landgraf, A.; Dzhumabaeva, A.; Abdrakhmatov, K. E.; Strecker, M. R.; Macaulay, E. A.; Arrowsmith, Jr.; Sudhaus, H.; Preusser, F.; Rugel, G.; Merchel, S.

    2016-05-01

    The northern Tien Shan of Kyrgyzstan and Kazakhstan has been affected by a series of major earthquakes in the late 19th and early 20th centuries. To assess the significance of such a pulse of strain release in a continental interior, it is important to analyze and quantify strain release over multiple time scales. We have undertaken paleoseismological investigations at two geomorphically distinct sites (Panfilovkoe and Rot Front) near the Kyrgyz capital Bishkek. Although located near the historic epicenters, both sites were not affected by these earthquakes. Trenching was accompanied by dating stratigraphy and offset surfaces using luminescence, radiocarbon, and 10Be terrestrial cosmogenic nuclide methods. At Rot Front, trenching of a small scarp did not reveal evidence for surface rupture during the last 5000 years. The scarp rather resembles an extensive debris-flow lobe. At Panfilovkoe, we estimate a Late Pleistocene minimum slip rate of 0.2 ± 0.1 mm/a, averaged over at least two, probably three earthquake cycles. Dip-slip reverse motion along segmented, moderately steep faults resulted in hanging wall collapse scarps during different events. The most recent earthquake occurred around 3.6 ± 1.3 kyr ago (1σ), with dip-slip offsets between 1.2 and 1.4 m. We calculate a probabilistic paleomagnitude to be between 6.7 and 7.2, which is in agreement with regional data from the Kyrgyz range. The morphotectonic signals in the northern Tien Shan are a prime example of deformation in a tectonically active intracontinental mountain belt and as such can help understand the longer-term coevolution of topography and seismogenic processes in similar structural settings worldwide.

  12. Fluid inclusion and H-O-C isotope geochemistry of the Yaochong porphyry Mo deposit in Dabie Shan, China: a case study of porphyry systems in continental collision orogens

    NASA Astrophysics Data System (ADS)

    Wang, Pin; Chen, Yan-Jing; Fu, Bin; Yang, Yong-Fei; Mi, Mei; Li, Zhong-Lie

    2014-04-01

    The Yaochong porphyry Mo deposit in Xinxian County, Henan Province, China, is located in the Hong'an terrane, that is, the western part of the Dabie orogen. The Dabie orogen is part of a >1,500 km long, Triassic continental collision belt between the North China Block and the South China Block. Four types of vein are present. Paragenetically, from early to late, they are as follows: stage 1 quartz + K-feldspar ± pyrite ± magnetite vein; stage 2 quartz + K-feldspar + molybdenite ± pyrite vein; stage 3 quartz + polymetallic sulfides ± K-feldspar vein; and stage 4 quartz ± carbonate ± fluorite vein. Four compositional types of fluid inclusion, pure CO2, CO2 bearing, aqueous, and solid bearing, are present in quartz from the first three stages; only low-salinity aqueous fluid inclusions occur in quartz from the last stage. All the estimated salinities are ≤13.1 wt% NaCl eq., and no halite crystals were identified. Homogenization temperatures for the fluid inclusions from stages 1 to 4 are in the ranges of 262-501, 202-380, 168-345, and 128-286 °C, respectively, and estimated depths decrease from 6.9 to 8.9 km, through 6.2-7.2, to ~4.7 km. Quartz separates from the veins yielded a δ18O value of 7.7-11.2 ‰, corresponding to δ18OH2O values of -1.3 to 6.9 ‰ using temperature estimates from fluid inclusion data; δDH2O values of fluid inclusion vary from -80 to -55 ‰, and δ13CCO2 from -2.3 to 2.7 ‰, suggesting that the ore-fluids evolved from magmatic to meteoric sources. We conclude that the ore-forming fluid system at Yaochong was initially high temperature, high salinity, and CO2-rich and then progressively evolved to CO2-poor, lower salinity, and lower temperature, by mixing with meteoric water, which results in ore precipitation.

  13. Ridge-trench collision in Archean and Post-Archean crustal growth: Evidence from southern Chile

    NASA Technical Reports Server (NTRS)

    Nelson, E. P.; Forsythe, R. D.

    1988-01-01

    The growth of continental crust at convergent plate margins involves both continuous and episodic processes. Ridge-trench collision is one episodic process that can cause significant magmatic and tectonic effects on convergent plate margins. Because the sites of ridge collision (ridge-trench triple junctions) generally migrate along convergent plate boundaries, the effects of ridge collision will be highly diachronous in Andean-type orogenic belts and may not be adequately recognized in the geologic record. The Chile margin triple junction (CMTJ, 46 deg S), where the actively spreading Chile rise is colliding with the sediment-filled Peru-Chile trench, is geometrically and kinematically the simplest modern example of ridge collision. The south Chile margin illustrates the importance of the ridge-collision tectonic setting in crustal evolution at convergent margins. Similarities between ridge-collision features in southern Chile and features of Archean greenstone belts raise the question of the importance of ridge collision in Archean crustal growth. Archean plate tectonic processes were probably different than today; these differences may have affected the nature and importance of ridge collision during Archean crustal growth. In conclusion, it is suggested that smaller plates, greater ridge length, and/or faster spreading all point to the likelihood that ridge collision played a greater role in crustal growth and development of the greenstone-granite terranes during the Archean. However, the effects of modern ridge collision, and the processes involved, are not well enough known to develop specific models for the Archean ridge collison.

  14. Initiation of extension in South China continental margin during the active-passive margin transition: kinematic and thermochronological constraints

    NASA Astrophysics Data System (ADS)

    ZUO, Xuran; CHAN, Lung

    2015-04-01

    The southern South China Block is characterized by a widespread magmatic belt, prominent NE-striking fault zones and numerous rifted basins filled by Cretaceous-Eocene sediments. The geology denotes a transition from an active to a passive margin, which led to rapid modifications of crustal stress configuration and reactivation of older faults in this area. In this study, we used zircon fission-track dating (ZFT) and numerical modeling to examine the timing and kinematics of the active-passive margin transition. Our ZFT results on granitic plutons in the SW Cathaysia Block show two episodes of exhumation of the granitic plutons. The first episode, occurring during 170 Ma - 120 Ma, affected local parts of the Nanling Range. The second episode, a more regional exhumation event, occurred during 115 Ma - 70 Ma. Numerical geodynamic modeling was conducted to simulate the subduction between the paleo-Pacific plate and the South China Block. The modeling results could explain the observation based on ZFT data that exhumation of the granite-dominant Nanling Range occurred at an earlier time than the gneiss-dominant Yunkai Terrane. In addition to the difference in geology between Yunkai and Nanling, the heating from Jurassic-Early Cretaceous magmatism in the Nanling Range may have softened the upper crust, causing the area to exhume more readily. Numerical modeling results also indicate that (1) high slab dip angle, high geothermal gradient of lithosphere and low convergence velocity favor the subduction process and the reversal of crustal stress state from compression to extension in the upper plate; (2) the late Mesozoic magmatism in South China was probably caused by a slab roll-back; and (3) crustal extension could have occurred prior to the cessation of plate subduction. The inversion of stress regime in the continental crust from compression to crustal extension has shed light on the geological condition producing the red bed basins during Late Cretaceous

  15. Zedong terrane revisited: An intra-oceanic arc within Neo-Tethys or a part of the Asian active continental margin?

    NASA Astrophysics Data System (ADS)

    Zhang, Liang-Liang; Liu, Chuan-Zhou; Wu, Fu-Yuan; Ji, Wei-Qiang; Wang, Jian-Gang

    2014-02-01

    granitic rocks also have positive ɛHf(t) values of ˜+12.6 to +15.2, implying their derivation from a juvenile lower crust. Therefore, we proposed that the basalts in the Zedong terrane were formed through partial melting of the mantle wedge metasomatized by slab-released fluids/melts. A part of hydrous basalts were underplated in the thickened lower crust beneath the Zedong terrane, which gave rise to the cumulate and granitic rocks. By comparison, magmatic rocks in the Zedong terrane show compositional similarities with the Jurassic rocks exposed in the Gangdese arc. This suggests that the Zedong terrane represents a slice of the active continental margin developed on the southern margin of the Lhasa terrane as a result of the northward subduction of the Neo-Tethys Ocean during the Late Jurassic, rather than the vestige of an intra-oceanic arc.

  16. Progressive Emergence and Warping of Islands in the Active Banda Arc-Continent Collision As Recorded By Uplifted Coral Terraces: Tectonic and Geohazards Implications

    NASA Astrophysics Data System (ADS)

    Harris, R. A.; Cox, N.; Major, J. R.; Merritts, D. J.; Prasetyadi, C.

    2014-12-01

    Uplifted coral terraces throughout the Banda-Sunda Arc transition reveal how strain is distributed over the past thousand to million years in the active arc-continent collision, and are key to identifying hazardous active faults. U-series age analysis of the lowest coral terraces yields surface uplift rates that vary in a non-systematic way along strike from 0.2 to 1.5 mm/a over short wavelengths of a few kms. For example, coral terraces are tilted varying degrees northward in Sumba, SSE in Savu, NNW in Rote and generally south along the north coast of Timor. In all of these cases the tilt is away from zones of active thrusting and folding. In Sumba the forearc is ramping up and over the northern edge of the Scott Plateau along what is likely a north dipping thrust. In Savu the coral terraces rise where the back of the accretionary wedge is ramping up over the forearc basin on the south dipping Savu Thrust. In Rote coral terraces form on the front of the accretionary wedge where it is ramping up over the subducting Australian continental margin. The north coast of East Timor is likely uplifting due to internal thrusting and closure of the Wetar Strait. Localized uplift of circular islands is associated with diapirism. The diapiric island of Kisar is cored by syn-collisional metamorphic rocks. The association of uplift and warping with short wavelength deformational processes argues against the commonly held interpretation that coral terraces in the Banda arc-continent collision manifest the effects of slab tear or some other lithospheric scale process. The pattern of uplift correlates best with proximity to active faults, folds and diapirs. In terms of geohazards, flights of uplifted coral terraces are the smoking gun for sources of large earthquakes and tsunami. Many of the terraces show signs of co-seismic uplift. Tsunami deposits with young corals are found on some of these terraces as high as 20 m above sea level.

  17. Dynamics of continental accretion.

    PubMed

    Moresi, L; Betts, P G; Miller, M S; Cayley, R A

    2014-04-10

    Subduction zones become congested when they try to consume buoyant, exotic crust. The accretionary mountain belts (orogens) that form at these convergent plate margins have been the principal sites of lateral continental growth through Earth's history. Modern examples of accretionary margins are the North American Cordilleras and southwest Pacific subduction zones. The geologic record contains abundant accretionary orogens, such as the Tasmanides, along the eastern margin of the supercontinent Gondwana, and the Altaïdes, which formed on the southern margin of Laurasia. In modern and ancient examples of long-lived accretionary orogens, the overriding plate is subjected to episodes of crustal extension and back-arc basin development, often related to subduction rollback and transient episodes of orogenesis and crustal shortening, coincident with accretion of exotic crust. Here we present three-dimensional dynamic models that show how accretionary margins evolve from the initial collision, through a period of plate margin instability, to re-establishment of a stable convergent margin. The models illustrate how significant curvature of the orogenic system develops, as well as the mechanism for tectonic escape of the back-arc region. The complexity of the morphology and the evolution of the system are caused by lateral rollback of a tightly arcuate trench migrating parallel to the plate boundary and orthogonally to the convergence direction. We find geological and geophysical evidence for this process in the Tasmanides of eastern Australia, and infer that this is a recurrent and global phenomenon. PMID:24670638

  18. Influence of surface active substances on bubble motion and collision with various interfaces.

    PubMed

    Malysa, K; Krasowska, M; Krzan, M

    2005-06-30

    Bubble motion as a function of distance from a point of its detachment and phenomena occurring during the bubble approach and collision with liquid/gas and liquid/solid interfaces in pure water and solutions of various surface active substances are described and discussed. It is showed that presence of surface active substance has a profound influence on values of the terminal velocity and profiles of the local velocity. At low solutions concentrations there are three distinct stages in the bubble motion: (i) a rapid acceleration, (ii) a maximum velocity value followed by its monotonic decrease, and (iii) attainment of the terminal velocity, while at high concentrations (and in pure water) there are only stages (i) and (iii). It is showed that the bubble terminal velocity decreases rapidly at low surfactant concentration, but there can be found some characteristic concentrations (adsorption coverage's) above which the velocity almost stopped to decrease. Immobilization of the bubble surface resulting from adsorption of the surface active substances (surface tension gradients inducement) causes over twofold lowering of the bubble velocity. Presence of the maximum on the local velocity profiles is an indication that a stationary non-uniform distribution of adsorption coverage (needed for immobilization the bubble interface) was not established there. When the rising bubble arrives at liquid/gas interface or liquid/solid interface there can be formed either foam or wetting film or three-phase contact (TPC). It is showed that prior to the foam and/or wetting film formation the bubble colliding with the interfaces can bounce backward and simultaneously its shape pulsates rapidly with a frequency over 1000 Hz. It is rather unexpected that even in the case of the free surface the bubble's shape and consequently its surface area can vary so rapidly. It shows straightforward that on such a rapidly distorted interface the adsorption coverage can be very different from that

  19. Images may show start of European-African plate collision

    NASA Astrophysics Data System (ADS)

    Mascle, J.; Huguen, C.; Benkhelil, J.; Chamot-Rooke, N.; Chaumillon, E.; Foucher, J. P.; Griboulard, R.; Kopf, A.; Lamarche, G.; Volkonskaia, A.; Woodside, J.; Zitter, T.

    Aspects of the initial stages of a collision between European and African plates may have been documented in a geophysical survey of the central Mediterranean Ridge (MR) conducted last year. The idea of an incipient collision was first suggested by Finetti [1976],and details of the seafloor and tectonic deformation along the MR, revealed for the first time in the survey, seem to point in that direction.A unique opportunity may therefore exist for studying the beginnings of such a collision—between the passive margin of a major plate (Africa) acting as a continental indenter against the active margin of another plate (Europe). More wide angle data, deep penetrating multichannel seismic data, and drilling data are crucial to better assess the nature and the architecture of the underlying lithosphere, the styles of sedimentary deformation, and the consequences on fluid releases. Such data will make it possible to establish, or reject, a geodynamic collision model.

  20. Active Strike-Slip Faulting in the Inner Continental Borderland, Southern California: Results From New High-Resolution Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Conrad, J. E.; Ryan, H. F.; Sliter, R. W.

    2008-12-01

    The inner Continental Borderland offshore of southern California accommodates about 7 mm/yr of slip between the North American and Pacific plates. Nearly half of this total has previously been thought to be taken up on the Palos Verdes (PV) and Coronado Bank (CB) fault zones, which have been modeled as a single, continuous fault zone in recent seismic hazard assessments for southern California. Although these faults lie roughly on strike with each other, a connection between these faults has not been clearly demonstrated. Newly acquired high-resolution seismic reflection data indicate that the PV fault terminates southwest of Lasuen Knoll in a horsetail splay that becomes progressively buried to the south. The lack of a connection between the PV and CB fault zones implies that a significant amount of slip must be taken up elsewhere in the inner Continental Borderland. Two other significant offshore faults, the San Diego Trough (SDT) and San Pedro Basin (SPB) fault zones, lie about 10-15 km southwest of and sub parallel to the trace of the PV and CB faults. The SDT fault zone extends from south of the Mexican border near Punta Santo Tomas for about 150 km northward to near Crespi Knoll. The SPB fault zone extends northward from off Santa Catalina Island to near Point Dume. The new seismic reflection data reveal a previously unmapped but apparently active fault zone along strike and in the area between the known strands of the SDT and the SPB fault zones. This newly recognized fault links the SDT and SPB faults, forming a continuous, active fault zone that extends about 250 km along the inner Continental Borderland. Although there are no slip rate data available for this fault zone, its overall length, continuity, and active character suggest that a significant portion of the plate motion that occurs offshore is accommodated along the SDT-SPB fault zone, which may pose a more significant seismic hazard than previously recognized.

  1. The northern Egyptian continental margin

    NASA Astrophysics Data System (ADS)

    Badawy, Ahmed; Mohamed, Gad; Omar, Khaled; Farid, Walid

    2015-01-01

    Africa displays a variety of continental margin structures, tectonics and sedimentary records. The northern Egyptian continental margin represents the NE portion of the North African passive continental margin. Economically, this region is of great importance as a very rich and productive hydrocarbon zone in Egypt. Moreover, it is characterized by remarkable tectonic setting accompanied by active tectonic processes from the old Tethys to recent Mediterranean. In this article, seismicity of the northern Egyptian continental margin has been re-evaluated for more than 100-years and the source parameters of three recent earthquakes (October 2012, January 2013 and July 2013) have been estimated. Moment tensor inversions of 19th October 2012 and 17th January 2013 earthquakes reveal normal faulting mechanism with strike-slip component having seismic moment of 3.5E16 N m and 4.3E15 N m respectively. The operation of the Egyptian National Seismic Network (ENSN) since the end of 1997 has significantly enhanced the old picture of earthquake activity across northern Egyptian continental margin whereas; the record-ability (annual rate) has changed from 2-events/year to 54-event/year before and after ENSN respectively. The spatial distribution of earthquakes foci indicated that the activity tends to cluster at three zones: Mediterranean Ridge (MR), Nile Cone (NC) and Eratosthenes Seamount (ERS). However, two seismic gaps are reported along Levant Basin (LEV) and Herodotus Basin (HER).

  2. Continental Jigsaw.

    ERIC Educational Resources Information Center

    Oringer, Richard H.

    1985-01-01

    The article outlines an activity for providing a hands-on opportunity for elementary and middle school science students to study the theory of the earth's crustal change over the past several hundred million years. The theory of continents drifting away from one super continent is presented with the supportive evidence that scientists have…

  3. Effective elastic thickness of the continental lithosphere in China from heat flow: Implications for the lithospheric rheology and active tectonics

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wang, L.

    2009-04-01

    The effective elastic thickness (Te) of continental lithosphere is one important parameter that describes the response of the lithosphere to long-term loads. However, the estimation of Te is still controversial and various forward and inverse methods have been proposed since the last 20 years. Besides the general application of gravity-topography based inverse method, thermal aspect and related technique is more emphasized, since the mechanical behavior of lithosphere is obviously influenced by temperature. Here we present the effective elastic thickness of the continental lithosphere in China from heat flow data by the method proposed by Burov et al, J. Geophys. Res., 1995, 100(B3):3905-3927. Our results show that Te varies much in different areas of China due to diverse and complicated geological evolution and associated change in thermal regime. Te is much larger than the crustal thickness in the regions where the heat flow is really low (usually less than 50mW/m2) and the lithosphere is relatively thick, indicating much more contribution from the upper mantle to the whole strength of lithosphere. Under this condition, the rheology of the mantle with olivine dominates the deformation manner and processes of the lithosphere and the typical cases in China are those blocks (Tarim, Junggar, Ordos and Sichuan) in central-western China. For instance, the Te of the Tarim basin is 66

  4. In situ observations of wave-supported fluid-mud generation and deposition on an active continental margin

    NASA Astrophysics Data System (ADS)

    Hale, Richard P.; Ogston, Andrea S.

    2015-11-01

    Wave-supported fluid muds (WSFM) are a type of gravity flow that can rapidly transport sediment across continental margins. They occur when wave-induced bed stress maintains suspended-sediment concentrations (SSC) >10 g L-1, and sediment-induced stratification near the top of the wave boundary layer limits upward diffusion of sediment. Observations from near-bed instrumentation are used to evaluate the conditions under which WSFMs form on the continental shelf offshore of the Waipaoa River, NZ. An event in July 2010 featured >130 h of energetic ocean conditions, and water discharge >1900 m3 s-1. A calibrated acoustic backscatter sensor at the midshelf measured near-bed SSC >50 g L-1, with a strong lutocline occurring >15 cm above the predicted wave-current boundary layer, resulting in ~5 cm deposition. A velocity anomaly occurred during this time, with offshore-directed currents faster at 1 m above bed (mab) than at 3.5 mab. Using these observations, we empirically solve a simple buoyancy-drag force balance to estimate the gravity-driven velocity of the WSFM, which is always <0.03 m s-1. Extending the force balance across a shelf transect suggests that WSFM-carried sediment can reach the shelf edge in 50-240 h. Spatial and temporal patterns of deposition predicted by the gradient of modeled sediment flux correlate well with seabed observations on the Waipaoa shelf reported in Walsh et al. (2014). This study highlights the importance of WSFMs for cross-shelf sediment transport, despite relatively slow gravity-driven velocities and the infrequency with which they occur.

  5. Estimates of suspended-sediment flux and bedform activity on the inner portion of the Eel continental shelf

    USGS Publications Warehouse

    Cacchione, D.A.; Wiberg, P.L.; Lynch, J.; Irish, J.; Traykovski, P.

    1999-01-01

    Energetic waves, strong bottom currents, and relatively high rates of sediment discharge from the Eel River combined to produce large amounts of suspended-sediment transport on the inner continental shelf near the Eel River during the winter of 1995-1996. Bottom-boundary-layer (BBL) measurements at a depth of ~50 m using the GEOPROBE tripod showed that the strongest near-bottom flows (combined wave and current speeds of over 1 m/s) and highest sediment concentrations (exceeding 2 g/l at ~1.2 m above the bed) occurred during two storms, one in December 1995 and the other in February 1996. Discharge from the Eel River during these storms was estimated at between 2 and 4 x 103 m3/s. Suspended-sediment flux (SSF) was measured 1.2 m above the bed and calculated throughout the BBL, by applying the tripod data to a shelf sediment-transport model. These results showed initially northward along-shelf SSF during the storms, followed by abrupt and persistent southward reversals. Along-shelf flux was more pronounced during and after the December storm than in February. Across-shelf SSF over the entire measurement period was decidedly seaward. This seaward transport could be responsible for surficial deposits of recent sediment on the outer shelf and upper continental slope in this region. Sediment ripples and larger bedforms were observed in the very fine to fine sand at 50-m depth using a sector-scanning sonar mounted on the tripod. Ripple wavelengths estimated from the sonar images were about 9 cm, which compared favorably with photographs of the bottom taken with a camera mounted on the tripod. The ripple patterns were stable during periods of low combined wave-current bottom stresses, but changed significantly during high-stress events, such as the February storm. Two different sonic altimeters recorded changes in bed elevation of 10 to 20 cm during the periods of measurement. These changes are thought to have been caused principally by the migration of low-amplitude, long

  6. Processes of lithosphere evolution: New evidence on the structure of the continental crust and uppermost mantle

    USGS Publications Warehouse

    Artemieva, I.M.; Mooney, W.D.; Perchuc, E.; Thybo, H.

    2002-01-01

    We discuss the structure of the continental lithosphere, its physical properties, and the mechanisms that formed and modified it since the early Archean. The structure of the upper mantle and the crust is derived primarily from global and regional seismic tomography studies of Eurasia and from global and regional data on seismic anisotropy. These data as documented in the papers of this special issue of Tectonophysics are used to illustrate the role of different tectonic processes in the lithospheric evolution since Archean to present. These include, but are not limited to, cratonization, terrane accretion and collision, continental rifting (both passive and active), subduction, and lithospheric basal erosion due to a relative motion of cratonic keels and the convective mantle. ?? 2002 Elsevier Science B.V. All rights reserved.

  7. Geophysical study of the structure and processes of the continental convergence zones: Alpine-Himalayan belt

    NASA Technical Reports Server (NTRS)

    Toksoz, M. N.; Molnar, P.

    1983-01-01

    Studies of the structure of the continental collision zones using seismic and body waves, theoretical modelling of the thermal regime of the convergence processes, and studies of earthquake mechanisms and deformation aspects of the model are covered.

  8. Gulf of Alaska continental slope morphology: Evidence for recent trough mouth fan formation

    NASA Astrophysics Data System (ADS)

    Swartz, John M.; Gulick, Sean P. S.; Goff, John A.

    2015-01-01

    continental shelves are host to numerous morphologic features that help understand past glacier dynamics. Southeastern Alaska is home to the St. Elias mountains, an active orogen that also hosts temperate marine glaciers. During glacial periods ice streams advance across the continental shelf, carving shelf-crossing troughs that reach the shelf edge. We use high-resolution multibeam data to develop the relationship between the Yakutat and Alsek Sea Valleys and the resulting continental slope morphology. The shelf and slope geomorphology can be divided into statistical groupings that relate to the relative balance of erosion and deposition. Our analysis indicates that only the Yakutat system has been able to build an incipient trough-mouth fan. The extreme sediment supply from this region was able to overwhelm the steep initial topography of the transform margin while further to the east sediment slope-bypass dominates. This analysis provides an extreme end member to existing studies of temperate glaciation along continental margins. The unique interplay between rapid uplift due to ongoing collision and the massive erosion caused by temperate glaciers provides for sedimentary flux far above most other systems.

  9. The rise and fall of continental arcs: Interplays between magmatism, uplift, weathering, and climate

    NASA Astrophysics Data System (ADS)

    Lee, Cin-Ty A.; Thurner, Sally; Paterson, Scott; Cao, Wenrong

    2015-09-01

    Continental arcs, such as the modern Andes or the Cretaceous Sierra Nevada batholith, are some of the highest topographic features on Earth. Continental arc volcanoes may produce more CO2 than most other types of volcanoes due to the interaction of magmas with sedimentary carbonates stored in the continental upper plate. As such, global flare-ups in continental arc magmatism may amplify atmospheric CO2 concentrations, leading to climatic warming. However, the high elevations of continental arcs may also enhance orographic precipitation and change global atmospheric circulation patterns, possibly increasing the efficiency of chemical weathering and drawdown of atmospheric CO2, which may subdue the climatic warming response to volcanic activity. To better evaluate the climatic response, we develop models that integrate magmatic crustal thickening, topographic uplift, isostasy and erosion. The topographic response is used to predict how soil formation rates, soil residence times, and chemical weathering rates vary during and after a magmatic episode. Although magmatism leads to crustal thickening, which requires topographic uplift, highest elevations peak ∼10 My after magmatism ends. Relatively high elevations, which enhance erosion and chemical weathering of the continental arc, persist for tens of million years after magmatism ends, depending on erosion kinetics. It has recently been suggested that the Cretaceous-Paleogene greenhouse (high atmospheric CO2 and warm climate) coincided with a global chain of continental arcs, whereas mid- to late Cenozoic icehouse conditions (low atmospheric CO2 and cold climate) coincided with a lull in continental arc activity after 50 Ma. Application of our models to the Sierra Nevada (California, USA) continental arc, which represents a segment of this global Cretaceous-Paleogene continental arc, reproduces the observed topographic and erosional response. Our models require that the newly formed continental arc crust remained

  10. Magmatic record of India-Asia collision.

    PubMed

    Zhu, Di-Cheng; Wang, Qing; Zhao, Zhi-Dan; Chung, Sun-Lin; Cawood, Peter A; Niu, Yaoling; Liu, Sheng-Ao; Wu, Fu-Yuan; Mo, Xuan-Xue

    2015-01-01

    New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80-40 Ma migrated from south to north and then back to south with significant mantle input at 70-43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52-51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma. PMID:26395973

  11. Magmatic record of India-Asia collision

    NASA Astrophysics Data System (ADS)

    Zhu, Di-Cheng; Wang, Qing; Zhao, Zhi-Dan; Chung, Sun-Lin; Cawood, Peter A.; Niu, Yaoling; Liu, Sheng-Ao; Wu, Fu-Yuan; Mo, Xuan-Xue

    2015-09-01

    New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80-40 Ma migrated from south to north and then back to south with significant mantle input at 70-43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52-51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma.

  12. Magmatic record of India-Asia collision

    PubMed Central

    Zhu, Di-Cheng; Wang, Qing; Zhao, Zhi-Dan; Chung, Sun-Lin; Cawood, Peter A.; Niu, Yaoling; Liu, Sheng-Ao; Wu, Fu-Yuan; Mo, Xuan-Xue

    2015-01-01

    New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80–40 Ma migrated from south to north and then back to south with significant mantle input at 70–43 Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52–51 Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70 Ma and slab breakoff at ca. 53 Ma. We propose that the slowdown of the Indian plate at ca. 51 Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55 Ma. PMID:26395973

  13. Syn- and post-orogenic alkaline magmatism in a continental arc: Along-strike variations in the composition, source, and timing of igneous activity in the Ross Orogen, Antarctica

    NASA Astrophysics Data System (ADS)

    Hagen-Peter, G.; Cottle, J. M.

    2013-12-01

    Neoproterozoic-Paleozoic convergence and subduction along the margin of East Gondwana (Australia, New Zealand, Antarctica) resulted in a belt of deformed and metamorphosed sedimentary rocks and batholith-scale igneous intrusions comparable in size to the present day Andes. Mid-crustal levels of this belt, known as the Ross Orogen in Antarctica, are exposed in the basement of the Cenozoic Transantarctic Mountains, providing snapshots of the intrusive magma system of a major continental arc. Whole rock major- and trace-element geochemistry, Hf isotopes in zircon, and U-Pb geochronology have identified along-strike variations in the composition, source, and timing of magmatism along ~200 km of the southern Victoria Land segment of the orogen. There is an apparent younging of the igneous activity from south to north. New U-Pb ages for intrusive rocks from the Koettlitz Glacier Alkaline Province (KGAP) reveal that igneous activity spanned ca. 565-500 Ma (~30 m.y. longer than previously recognized), while immediately to the north in the Dry Valleys area most igneous activity was confined to a relatively short period (ca. 515-495 Ma). Alkaline and subalkaline igneous rocks occur in both the Dry Valleys area and the KGAP, but alkaline rocks in the Dry Valleys are restricted to the latest phase of magmatism. Na-alkaline rocks in the KGAP, including nepheline syenites, carbonatites, and A-type granites, range in age from ca. 545-500 Ma and overlap in age with more typical subduction/collision-related I- and S-type granites elsewhere in southern Victoria Land. Strong enrichments in the LILE and LREE and high LILE/HFSE and LREE/HREE of samples from the KGAP reveal a source enriched in aqueous-mobile elements, potentially a strongly metasomatized mantle wedge beneath the arc. In the Dry Valleys area, rocks with alkali-calcic composition constitute only the youngest intrusions (505-495 Ma), apparently reflecting a shift to post-orogenic magmatism. Zircons from Dry Valleys

  14. Joint geophysical and petrological models for the lithosphere structure of the Antarctic Peninsula continental margin

    NASA Astrophysics Data System (ADS)

    Yegorova, Tamara; Bakhmutov, Vladimir; Janik, Tomasz; Grad, Marek

    2011-01-01

    The Antarctic Peninsula (AP) is a composite magmatic arc terrane formed at the Pacific margin of Gondwana. Through the late Mesozoic and Cenozoic subduction has stopped progressively from southwest to northeast as a result of a series of ridge trench collisions. Subduction may be active today in the northern part of the AP adjacent to the South Shetland Islands. The subduction system is confined by the Shackleton and Hero fracture zones. The magmatic arc of the AP continental margin is marked by high-amplitude gravity and magnetic anomaly belts reaching highest amplitudes in the region of the South Shetland Islands and trench. The sources for these anomalies are highly magnetic and dense batholiths of mafic bulk composition, which were intruded in the Cretaceous, due to partial melting of upper-mantle and lower-crustal rocks. 2-D gravity and magnetic models provide new insights into crustal and upper-mantle structure of the active and passive margin segments of the northern AP. Our models incorporate seismic refraction constraints and physical property data. This enables us to better constrain both Moho geometry and petrological interpretations in the crust and upper mantle. Model along the DSS-12 profile crosses the AP margin near the Anvers Island and shows typical features of a passive continental margin. The second model along the DSS-17 profile extends from the Drake Passage through the South Shetland Trench/Islands system and Bransfield Strait to the AP and indicates an active continental margin linked to slow subduction and on-going continental rifting in the backarc region. Continental rifting beneath the Bransfield Strait is associated with an upward of hot upper mantle rocks and with extensive magmatic underplating.

  15. Deep continental margin reflectors

    USGS Publications Warehouse

    Ewing, J.; Heirtzler, J.; Purdy, M.; Klitgord, Kim D.

    1985-01-01

    In contrast to the rarity of such observations a decade ago, seismic reflecting and refracting horizons are now being observed to Moho depths under continental shelves in a number of places. These observations provide knowledge of the entire crustal thickness from the shoreline to the oceanic crust on passive margins and supplement Consortium for Continental Reflection Profiling (COCORP)-type measurements on land.

  16. Freshly brewed continental crust

    NASA Astrophysics Data System (ADS)

    Gazel, E.; Hayes, J. L.; Caddick, M. J.; Madrigal, P.

    2015-12-01

    Earth's crust is the life-sustaining interface between our planet's deep interior and surface. Basaltic crusts similar to Earth's oceanic crust characterize terrestrial planets in the solar system while the continental masses, areas of buoyant, thick silicic crust, are a unique characteristic of Earth. Therefore, understanding the processes responsible for the formation of continents is fundamental to reconstructing the evolution of our planet. We use geochemical and geophysical data to reconstruct the evolution of the Central American Land Bridge (Costa Rica and Panama) over the last 70 Ma. We also include new preliminary data from a key turning point (~12-6 Ma) from the evolution from an oceanic arc depleted in incompatible elements to a juvenile continental mass in order to evaluate current models of continental crust formation. We also discovered that seismic P-waves (body waves) travel through the crust at velocities closer to the ones observed in continental crust worldwide. Based on global statistical analyses of all magmas produced today in oceanic arcs compared to the global average composition of continental crust we developed a continental index. Our goal was to quantitatively correlate geochemical composition with the average P-wave velocity of arc crust. We suggest that although the formation and evolution of continents may involve many processes, melting enriched oceanic crust within a subduction zone, a process probably more common in the Achaean where most continental landmasses formed, can produce the starting material necessary for juvenile continental crust formation.

  17. Cenozoic evolution of the Antarctic Peninsula continental margin

    SciTech Connect

    Anderson, J.B. )

    1990-05-01

    Cenozoic evolution of the Antarctic Peninsula continental margin has involved a series of ridge (Aluk Ridge)-trench collisions between the Pacific and Antarctic plates. Subduction occurred episodically between segments of the Pacific plate that are bounded by major fracture zones. The age of ridge-trench collisions decreases from south to north along the margin. The very northern part of the margin, between the Hero and Shackleton fracture zones, has the last surviving Aluk-Antarctic spreading ridge segments and the only remaining trench topography. The sedimentary cover on the northern margin is relatively thin generally less than 1.5 km, thus providing a unique setting in which to examine margin evolution using high resolution seismic methods. Over 5,000 km of high resolution (water gun) seismic profiles were acquired from the Antarctic Peninsula margin during four cruises to the region. The margin is divided into discrete fracture-zone-bounded segments; each segment displays different styles of development. Highly tectonized active margin sequences have been buried beneath a seaward-thickening sediment wedge that represents the passive stage of margin development Ice caps, which have existed in the Antarctic Peninsula region since at least the late Oligocene, have advanced onto the continental shelf on numerous occasions, eroding hundreds of meters into the shelf and depositing a thick sequence of deposits characterized by till tongues and glacial troughs. Glacial erosion has been the main factor responsible for overdeepening of the shelf; isostasy is of secondary importance. As the shelf was lowered by glacial erosion, it was able to accommodate thicker and more unstable marine ice sheets. The shelf also became a vast reservoir for cold, saline shelf water, one of the key ingredients of Antarctic bottom water.

  18. Intraoceanic Arc Tectonic and Sedimentary Processes: Translation from Modern Activity to Ancient Records

    NASA Astrophysics Data System (ADS)

    Draut, A. E.; Clift, P. D.

    2013-12-01

    Records of ancient intraoceanic arc activity, now preserved in continental suture zones, are used to reconstruct paleogeography, plate motion, collision and accretion events, and to understand how continental crust is formed, recycled, and maintained through time. However, interpreting tectonic and sedimentary records after arc-continent collision is complicated by preservation of evidence for some processes and loss of evidence for others. We examine what is lost, and what is preserved, in the translation from modern processes to the ancient record of oceanic subduction zones. Composition of accreted arc terranes differs as a function of arc-continent collision geometry. ';Forward-facing' collision can accrete an oceanic arc onto either a passive or an active continental margin, with the arc facing the continent and colliding trench- and forearc-side first. In ';backward-facing' collision, involving two subduction zones with similar polarity, the arc collides backarc-first with an active continental margin. The preservation of evidence for contemporary sedimentary and tectonic arc processes in the geologic record depends greatly on how well the various parts of the arc survive collision and orogeny in each case. Preservation of arc terranes likely is biased towards those that were in tectonic accretion for tens of millions of years before collision, rather than tectonic erosion. The prevalence of tectonic erosion in modern oceanic subduction zones implies that valuable records of arc processes are commonly destroyed even before collision with a continent. Arc systems are most likely to undergo tectonic accretion shortly before forward-facing collision with a continent, and thus most forearc and accretionary-prism material in ancient arc terranes likely is temporally biased toward the final stages of arc activity, when sediment flux to the trench was greatest. Collision geometry and tectonic erosion vs. accretion are important controls on the ultimate survival of

  19. Tectonic escape in the evolution of the continental crust

    NASA Technical Reports Server (NTRS)

    Burke, K.; Sengor, C.

    1986-01-01

    The continental crust originated by processes similar to those operating today and continents consist of material most of which originated long ago in arc-systems that have later been modified, especially at Andean margins and in continental collisions where crustal thickening is common. Collision-related strike-slip motion is a general process in continental evolution. Because buoyant continental (or arc) material generally moves during collision toward a nearby oceanic margin where less buoyant lithosphere crops out, the process of major strike-slip dominated motion toward a 'free-face' is called 'tectonic escape'. Tectonic escape is and has been an element in continental evolution throughout recorded earth-history. It promotes: (1) rifting and the formation of rift-basins with thinning of thickened crust; (2) pervasive strike-slip faulting late in orogenic history which breaks up mountain belts across strike and may juxtapose unrelated sectors in cross-section; (3) localized compressional mountains and related foreland-trough basins.

  20. Transition from collision to subduction in Western Greece: the Katouna-Stamna active fault system and regional kinematics

    NASA Astrophysics Data System (ADS)

    Pérouse, E.; Sébrier, M.; Braucher, R.; Chamot-Rooke, N.; Bourlès, D.; Briole, P.; Sorel, D.; Dimitrov, D.; Arsenikos, S.

    2016-06-01

    Transition from subduction to collision occurs in Western Greece and is accommodated along the downgoing plate by the Kefalonia right-lateral fault that transfers the Hellenic subduction front to the Apulian collision front. Here we present an active tectonic study of Aitolo-Akarnania (Western Greece) that highlights how such a transition is accommodated in the overriding plate. Based on new multi-scale geomorphic and tectonic observations, we performed an accurate active fault trace mapping in the region, and provide evidence for active normal and left-lateral faulting along the Katouna-Stamna Fault (KSF), a 65-km-long NNW-striking fault system connecting the Amvrakikos Gulf to the Patras Gulf. We further show that the Cenozoic Hellenide thrusts located west of the KSF are no longer active, either in field observation or in GPS data, leading us to propose that the KSF forms the northeastern boundary of a rigid Ionian Islands-Akarnania Block (IAB). Cosmic ray exposure measurements of 10Be and 36Cl were performed on a Quaternary alluvial fan offset along the KSF (~50 m left-lateral offset). A maximum abandonment age of ~12-14 ka for the alluvial fan surface can be determined, giving an estimated KSF minimum geological left-lateral slip rate of ~4 mm year-1, in agreement with high GPS slip rates (~10 mm year-1). Despite this high slip rate, the KSF is characterized by subdued morphological evidence of tectonic activity, a gypsum-breccia bedrock and a low level of seismicity, suggesting a dominantly creeping behavior for this fault. Finally, we discuss how the IAB appears to have been progressively individualized during the Pleistocene (younger than ~1.5 Ma).

  1. Violent Gas Venting on the Heng-Chun Mud Volcano, South China Sea Active Continental Margin offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, S.; Cheng, W. Y.; Tseng, Y. T.; Chen, N. C.; Hsieh, I. C.; Yang, T. F.

    2014-12-01

    Accumulation of methane as gas hydrate under the sea floor has been considered a major trap for both thermal and biogenic gas in marine environment. Aided by rapid AOM process near the sea floor, fraction of methane escaping the sea floor has been considered at minuscule. However, most studies focused mainly on deepwater gas hydrate systems where gas hydrate remain relatively stable. We have studied methane seeps on the active margin offshore Taiwan, where rapid tectonic activities occur. Our intention is to evaluate the scale and condition of gas seeps in the tectonic active region. Towcam, coring, heat probe, chirp, multibeam bathymetric mapping and echo sounding were conducted at the study areas. Our results showed that gas is violently venting at the active margin, not only through sediments, but also through overlying sea water, directly into the atmosphere. Similar ventings, but, not in this scale, have also been identified previously in the nearby region. High concentrations of methane as well as traces of propane were found in sediments and in waters with flares. In conjunction, abundant chemosynthetic community, life mussel, clams, tube worms, bacterial mats together with high concentrations of dissolve sulfide, large authigenic carbonate buildups were also found. Our results indicate that methane could be another major green house gas in the shallow water active margin region.

  2. 75 FR 54372 - BOEMRE Information Collection Activity: 1010-0081, Operations in the Outer Continental Shelf for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-07

    ... Bureau of Ocean Energy Management, Regulation, and Enforcement BOEMRE Information Collection Activity..., Extension of a Collection; Comment Request AGENCY: Bureau of Ocean Energy Management, Regulation, and... . Mail or hand-carry comments to the Department of the Interior; Bureau of Ocean Energy...

  3. Continental crust beneath southeast Iceland.

    PubMed

    Torsvik, Trond H; Amundsen, Hans E F; Trønnes, Reidar G; Doubrovine, Pavel V; Gaina, Carmen; Kusznir, Nick J; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D; Griffin, William L; Werner, Stephanie C; Jamtveit, Bjørn

    2015-04-14

    The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume. PMID:25825769

  4. Continental crust beneath southeast Iceland

    PubMed Central

    Torsvik, Trond H.; Amundsen, Hans E. F.; Trønnes, Reidar G.; Doubrovine, Pavel V.; Gaina, Carmen; Kusznir, Nick J.; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D.; Griffin, William L.; Werner, Stephanie C.; Jamtveit, Bjørn

    2015-01-01

    The magmatic activity (0–16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland—and especially the Öræfajökull volcano—is characterized by a unique enriched-mantle component (EM2-like) with elevated 87Sr/86Sr and 207Pb/204Pb. Here, we demonstrate through modeling of Sr–Nd–Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2–6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume. PMID:25825769

  5. Influence of explosive volcanic events on the activation versus de-activation of a modern turbidite system: the example of the Dohrn canyon-fan in the continental slope of the Campania volcanic district (Naples Bay, Italy - Western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Roca, M.; Budillon, F.; Pappone, G.; Insinga, D.

    2015-12-01

    The interplay between volcanic activity, volcano-clastic yield and activation/deactivation of a turbidite system can be evaluated along the continental margin of Campania region (Tyrrhenian Sea - Italy), an active volcanic area, where three wide canyon-fans occur at short distances one to another. Actually, the Dohrn, Magnaghi and Cuma canyons cut the continental slope and shelf off Ischia and Procida volcanic islands and off the Campania Plain where Phlegraean Field and Mt. Vesuvius active vents are located. This research, partly supported by the Italian Flagship Project Ritmare, is based on single-channel, high-resolution seismic profiles (Sparker-One 16 kJ, 0.5 s twtt), swath-bathymetry and litho- and tephra-stratigraphy of gravity cores. We focused on the stratigraphic constraint of paleo-thalweg features and channel/levees deposits in seismics, debris flow, turbidites and hemipelagites in cores, to learn more on the activation/deactivation stages of the canyon Dohrn, in the frame of relative eustatic sea level variations over the Middle Pleistocene-Holocene time span.Preliminary outcomes suggest that even major volcanic events occurred in the last 300 ky, such as ignimbrite eruptions or large fallouts, have caused the infilling of the canyon head and the cover of pre-existing seabed morphology. As a consequence, the temporary deactivation of the turbidite system has occurred, despite the volcano-clastic overload in the coastal environment. Phases of renewed activities of the thalweg are observed to be in step with falling stages of sea level, which have driven the re-incision of canyon valleys through continuous volcano-clastic debris and turbidites down-flows. Since Holocene, the quiescence of the Dohrn Canyon has been documented, despite the intense volcano-tectonic activity in the area.

  6. U-Pb geochronology and petrology of the late Paleozoic Gil Marquez pluton: magmatism in the Variscan suture zone, southern Iberia, during continental collision and the amalgamation of Pangea

    NASA Astrophysics Data System (ADS)

    Gladney, Evan R.; Braid, James A.; Murphy, J. Brendan; Quesada, Cecilio; McFarlane, Christopher R. M.

    2014-07-01

    The origin of plutonic complexes that stitch suture zones developed during collision is not well understood. In southern Iberia, the Pulo du Lobo suture zone (PDLZ) is intruded by the syn- to postcollisional Gil Marquez pluton (GMP), thought to be part of the Sierra Norte Batholith. U-Pb (LA-ICPMS, zircon) data on various phases of the GMP yield from oldest to youngest: (1) a 354.4 ± 7.6 Ma unfoliated gabbro; (2) a 345.6 ± 2.5 Ma foliated intermediate phase; (3) a 346.5 ± 5.4 Ma unfoliated porphyritic granite; (4) a 335.1 ± 2.8 Ma unfoliated biotite granite. This sequence is consistent with cross-cutting relationships observed in the field. The range in ages is consistent with interpretations that the GMP is part of the composite (ca. 350-308 Ma) SNB. Inherited ages preserved in the GMP intermediate and felsic phases indicate that its magmas traversed through South Portuguese Zone and PDLZ crust during emplacement. The ca. 345 Ma emplacement of the late kinematic foliated intermediate phase constrains the age of late-stage strike slip deformation within the PDLZ, and the lack of a foliation in the older gabbro indicates that is was not proximal to a shear zone neither at the time of emplacement, nor during its subsequent history. The unfoliated porphyritic granite and unfoliated biotite granite cut the foliation of the intermediate phase indicating emplacement during the waning stages of collision, while the ca. 335 Ma biotite granite intrudes the Santa Ira Flysch, thereby providing a tight constraint for the latest stage of deformation in the PDLZ.

  7. Neoproterozoic active continental margin in the southeastern Yangtze Block of South China: Evidence from the ca. 830-810 Ma sedimentary strata

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhou, Mei-Fu; Zhao, Jun-Hong; Pandit, Manoj K.; Zheng, Jian-Ping; Liu, Ze-Rui

    2016-08-01

    The Jiangnan Fold Belt in the South China Block has been traditionally assumed to be Mesoproterozoic in age and related to the global Grenville orogeny. Sedimentary successions in the Jiangnan Fold Belt archive direct record of tectonic evolution; however, they have not yet been evaluated properly. The Lushan massif, comprising Kangwanggu and Xingzi groups, is the major basement complex in the Jiangnan Belt. Regional correlation of these two groups is poorly constrained, such as with the Shuangqiaoshan group, and thus their role in the regional tectonic evolution is not clear. Detrital zircon U-Pb ages suggest that the Xingzi and Kangwanggu groups were deposited at 820-810 and ca. 830 Ma, respectively. They are composed of dominantly felsic to intermediate volcanic detritus, as indicated by the relatively high Th/Cr (0.24-0.06) ratios and radiogenic Nd isotopes (εNd(t) values = + 1.5 to - 2.9) of the sedimentary rocks. An overwhelming abundance of Neoproterozoic (ca. 860-810 Ma) angular, detrital zircon grains in both the groups indicates derivation chiefly from locally distributed syn-sedimentary igneous rocks. A predominance of zircons with ages close to the time of deposition implies a convergent plate margin setting for Kangwanggu and Xingzi groups. Geochemical signatures, such as La-Th-Co and Th-Sc-Zr/10 plots for Xingzi and Kangwanggu sedimentary rocks also underline tectonically active settings, consistent with the arc affinity of the associated mafic and felsic volcanic rocks. In contrast to the dominant Neoproterozoic detritus in the Kangwanggu sandstone, argillaceous rocks of the Xingzi group received additional input of pre-Neoproterozoic detritus. Moreover, the Xingzi argillaceous rocks have εNd(t) values (+ 0.9 to - 2.9) slightly lower than those of the Kangwanggu sandstones (+ 1.5 to 0.0), indicating contribution from mature crustal materials exposed during progressive uplift of continental basement during orogenesis. These features suggest the

  8. Non-thermal Radiation from Collisions of Compact Objects with Intermediate-scale Jets in Active Galaxies

    NASA Astrophysics Data System (ADS)

    Bednarek, W.; Banasiński, P.

    2015-07-01

    Massive black holes in active galaxies are immersed in huge concentrations of late-type stars in the galactic bulges and also early-type massive stars in the nuclear stellar clusters, which are additionally surrounded by quasi-spherical halos on a scale of several kpc that contain from a few hundred up to several thousand globular clusters (GCs). It is expected that significant numbers of red giant stars, massive stars, and also GCs can move through the jet expelled from the central engine of the active galaxy. We consider collisions of stars from the galactic bulge, nuclear cluster, and GCs with the jet plasma. As a result of such collisions, multiple shocks are expected to appear in the jet around these compact objects. Therefore, the plasma in the kpc-scale jet can be significantly disturbed. We show that particles can be accelerated on these shocks up to multi-TeV energies. TeV leptons emit synchrotron radiation, extending up to X-ray energies, and also comptonize radiation produced in a stellar cluster and also the microwave background radiation to TeV γ-ray energies. We show that such non-thermal radiation is likely to be detectable from the intermediate-scale jets of nearby active galaxies for a reasonable number of stars and GCs immersed within the jet. As an example, we calculate the expected non-thermal emission in X-ray and gamma-ray energies from the nearby radio galaxy Cen A, from which steady gamma-ray emission with a complex spectrum has recently been reported by Fermi and the HESS Observatories.

  9. Impacts of Sea-Level Rise and Human Activity on a Tropical Continental Shelf, RN State, NE Brazil

    NASA Astrophysics Data System (ADS)

    Vital, H.; Barros Pereira, T. R.; Lira, H. F.; Tabosa, W. F.; Eichler, P.; Stattegger, K.; Sen Gupta, B. K.; Gomes, M. P.; Nogueira, M. L. D. S.; Pierri, G. C. S.

    2014-12-01

    The northeastern Brazilian, tropical coast-shelf system along the Atlantic Ocean is a sediment-starved zone, because of low relief, small drainage basins, and a semiarid climate. This work presents the major results of a study of environmental changes, particularly those related to Holocene sea-level rise, affecting the coast and shallow waters of Rio Grande do Norte (RN) State, NE Brazil. The methods included bottom-sediment characterization, bioindicator tracking, and integrated shallow-water geophysical investigation. This coastline is marked by active sea cliffs carved into tablelands alternating with reef- or dune-barrier sections, beach rocks and lagoons, whereas the shelf is a narrow, very shallow, and highly energetic system. Overall, the area is under the natural influence of tides (with a semidiurnal mesotidal regime) and the anthropogenic influence of salt exploration, oil industry, shrimp farms, tourism, and wind-farms. Sedimentation during the Holocene has been controlled mainly by sea-level variation, longshore currents, and the advance and westward propagation of active dunes along the coast. As in other areas around the world, growing numbers of permanent and seasonal residents choose to live at or near the ocean. Coastal erosion is a cause for concern along many Brazilian beaches, and several erosion hot spots are already recognized in RN State. Curves of Holocene relative sea-level variation were established for RN State, but the absence of long-term oceanographic observations in the last centuries or that of detailed altimetry maps hinders the evaluation of different risk scenarios at the local level. Nevertheless, impacts of the current sea-level rise and human activity can be observed along the RN coastal-shelf system. Particular aspects of the study, such as oil-spill monitoring, coastal-water sewage contamination, and coastal erosion, will be highlighted.

  10. Active Tectonics In The Rukwa Rift (sw Tanzania): A Study of The Potential For Large Earthquakes In A Continental Rift.

    NASA Astrophysics Data System (ADS)

    Kervyn, F.

    The Rukwa rift is a deep sedimentary basin that is considered as a tectonic trans- fer zone between the Tanganyika and the Malawi troughs. The tectonic evolution of the depression is controlled by the reactivation of proterozoic structures and started with the deposition of the permo-triasic Karoo sediments. In the southeast, the rift is divided into two facing half graben separated by a Precambrian horst, whereas its northwestern part has a more symmetrical graben structure. Although most of the vertical displacement is accommodated by the Lupa eastern boundary fault, onshore shallow seismic profiles have confirmed the co-occurrence of intrabasin synthetic- and strike-slip faults within the sub surface sediments. Both normal and dextral strike-slip movement are indeed observed in the basin in response to the E-W to WNW-SSE ex- tension. The region has a moderate seismic activity and the earthquakes magnitude is generally below M 6.5. However, a M 7.4 earthquake occurred in the Rukwa region in 1910 but its exact location remains uncertain. The current research aimed at the identi- fication of active faults within the recent deposits of the basin by the combination in a GIS of radar interferometric data with topographical and geological maps, geophysical data, and field observations. Radar interferometry (InSAR) was found to be especially suitable for DEM computation in low relief areas where available topographic data are limited in accuracy. Numerous topographic lineaments were observed on InSAR DEM, and follow two main directions, both oblique to the main NW-SE trend of the rift. On the one hand, the GIS analysis confirms that the observed lineaments corre- spond to real natural alignment such like the drainage for example, and are therefore not related to atmospheric artefacts. On the other hand, the field observations revealed that in most cases, the topographic lineaments are very subtle and difficult to identify. However, direct correlations with tectonic

  11. Tibet and Beyond: Magmatic Records from CIA (Caucasus-Iran-Anatolia) and Southern Tibet with Implications for Asian Orogeny and Continental Growth

    NASA Astrophysics Data System (ADS)

    Chung, Sun-Lin

    2016-04-01

    This study, based on an ongoing joint research project "Tibet and Beyond", presents a synthesis of principal magmatic records from the CIA (Caucasus-Iran-Anatolia) and Tibet-Himalaya orogens resulting from the continental collisions of Arabia and India, respectively, with Eurasia. In both orogens, through this and other recent studies, the temporal and spatial variations in magmatism pre-, syn- and post-dating the collisions can now be much better defined, thus improving our understanding of collision zone magmatism that appears to have evolved with changes in the lithospheric structures over time and space by collisional processes. The two "collisional" Tethyan orogens were preceded by accretionary orogenic processes, which not only had produced a substantial amount of juvenile continental crust but also fulfill the "orogenic cycle" that evolved from an accretionary into a collisional system. Geochemical data reveal that in contrast to generating vast portions of juvenile crust in the early, accretionary stages of orogenic development, crustal recycling plays a more important role in the later, collisional stages. The latter, as exemplified in SE Turkey and southern Tibet, involves addition of older continental crust material back into the mantle, which subsequently melted and caused compositional transformation of the juvenile crust produced in the accretionary stages. Similar features are observed in young volcanic rocks from eastern Taiwan, the northern Luzon arc complex and part of the active subduction/accretion/collision system in Southeast Asia that may evolve one day to resemble the eastern Tethyan and central Asian orogenic belts by collision with the advancing Australian continent.

  12. The timing of India-Asia collision onset - facts, theories, controversies

    NASA Astrophysics Data System (ADS)

    Hu, Xiumian; Garzanti, Eduardo; Wang, Jiangang; Huang, Wentao; An, Wei; Webb, Alex

    2016-04-01

    The timing of initial collision between India and Asia has remained grossly and windingly controversial for half a century. This paper attempts to review this crucial and hotly debated argument, describing first the different methods used to constrain the age of collision and discussing next the rationale, results, inferences and problems associated with each. We conclude that stratigraphy represents the best direct way to unravel collision chronology. Other methods focusing on the magmatic, metamorphic or paleomagnetic record provide additional fundamental constraints, but cannot provide a robust direct estimate of collision onset. Initial collision in the central-eastern Himalaya is dated directly at the Middle Paleocene (59±1 Ma) by the abrupt change in sediment provenance recorded in trench settings (Hu et al., 2015). The quasi-synchronous unconformities documented along both Tethyan passive margin of India and active margin of Asia from Tibet to Zanskar-Ladakh confirm that orogeny was underway at the close of the Paleocene (56 Ma) (Garzanti et al., 1987; Li et al., 2015; Hu et al., 2016), well before the disappearance of marine seaways in the Himalaya during the Eocene (50 Ma) (Najman et al., 2010). Sedimentary evolution and provenance changes in marine to fluvio-deltaic successions are recorded synchronously within error from the western to the central-eastern Himalaya, failing to provide evidence for diachronous collision. These coherent observations are hard to reconcile with three widely cited hypotheses invoking either earlier events of arc-continent collision or ophiolite obduction, or the protracted existence of a Greater India Basin, which should be all rejected after discussing the geological evidence. A scenario no more complex than the one involving solely the passive continental margin of India and the active continental margin of Asia is needed to explain the geological evolution of the nascent Himalaya. The collision between the Tethys

  13. The transition from hydrostatic to greater than hydrostatic fluid pressure in presently active continental hydrothermal systems in crystalline rock

    SciTech Connect

    Fournier, R.O. )

    1991-05-01

    Fluid flow at hydrostatic pressure (P{sub h}) is relatively common through fractures in silicic and in mafic crystalline rocks where temperatures are less than about 350-370C. In contrast, pore-fluid pressure (P{sub f}) > P{sub h} has been encountered at the bottom of 3 geothermal exploration wells that attained temperatures >370C (at Larderello, Italy, at Nesjavellir, Iceland, and at The Geysers, California). Chemical sealing by deposition of minerals in veins appears to have allowed the development of the high P{sub f} encountered in the above wells. The upper limit for the magnitude of P{sub f} that can be attained is controlled by either the onset of shear fracturing (where differential stress is relatively high) that reopens clogged veins, or the hydraulic opening of new or old fractures (at relatively low values of differential stress). The brittle-plastic transition for silicic rocks can occur at temperatures as high as 370-400C in tectonically active regions. In regions where high-temperature geothermal systems develop and persist, it appears that either strain rates commonly are in the range 10{sup {minus}12} to 10{sup {minus}13}, or that silicic rocks in the shallow crust generally behave rheologically more like wet quartz diorite than wet Westerly granite.

  14. Determining how the pelagic ecosystem over the continental shelf of the Bay of Biscay (NE Atlantic) functions: An approach using mesozooplankton enzyme activities as descriptors

    NASA Astrophysics Data System (ADS)

    Bergeron, Jean-Pierre; Delmas, Daniel; Koueta, Noussithé

    2009-04-01

    A fisheries research cruise conducted in 2000 offered a first opportunity to take simultaneous measurements of the activities of three enzymes in mesozooplankton samples collected at a regional scale over the continental shelf of the Bay of Biscay in the NE Atlantic, with the aim of characterizing main aspects of the functioning of the biotic environment of small pelagic fish populations. The activity of the digestive endopeptidase trypsin was selected to characterize the assimilation rate of proteins, whereas pyruvate kinase (PK) was chosen as an indicator of carbohydrate assimilation and aspartate transcarbamylase (ATC) provided an overall assessment of mesozooplankton productivity. The Bay of Biscay region is subject to various strong physical driving forces that directly affect the primary structure of the pelagic food web. On our cruise, the phytoplankton biomass distribution reflected these different physical influences: diatoms dominated the nutrient-enriched coastal water; picoplankton dominated the northern-central part where nutrients were depleted; and nanoplankton were abundant at the shelf break where internal waves provided an input of nutrients. These and other results (on bacteria, particulate organic carbon distribution, among others) illustrate the differences that exist in the microbial food webs of different sectors of the bay. The living matter produced was characterized by the quality and quantity of the smallest prey items that were available to higher trophic levels. Variations in mesozooplankton enzyme activities may agree well not only with classically expected results, but also present unexpected special features: high ATC specific activities were measured around the mouth of the Gironde, in the nutrient-rich desalted water of the plume, but surprisingly not in front of the Loire river. PK specific activities reflected preponderantly the balance between phytoplankton cells sizes and the related bacterial abundance resulting from nutrient

  15. Cospatial Eocene and Miocene granitoids from the Jiru Cu deposit in Tibet: Petrogenesis and implications for the formation of collisional and postcollisional porphyry Cu systems in continental collision zones

    NASA Astrophysics Data System (ADS)

    Yang, Zhiming; Hou, Zengqian; Chang, Zhaoshan; Li, Qiuyun; Liu, Yunfei; Qu, Huanchun; Sun, Maoyu; Xu, Bo

    2016-02-01

    Jiru is a poorly studied Cu deposit located in the west segment of the Gangdese porphyry Cu belt (GPCB), 200 km west of Lhasa. The deposit consists of both collisional- and postcollisional-stage porphyry-type Cu systems, which are genetically associated with the early Eocene granitoid batholith and the Miocene Jiru porphyry stock, respectively. In this study, we present zircon U-Pb LA-ICP-MS dates and Hf isotopes, whole rock geochemical and Pb isotope geochemical data for the main intrusions in the Jiru deposit. The early Eocene granitoid samples (~ 49 Ma) are characterized by magmatic arc geochemical features, slightly concave REE patterns and well-developed negative Eu anomalies. These geochemical characteristics suggest that the granitoid melts were generated by partial melting of a metasomatized mantle, and that the melt had undergone fractional crystallization of amphibole and plagioclase. In contrast, the Miocene porphyry intrusions (16.4-15.5 Ma) at Jiru are characterized by high K contents, adakitic affinities (e.g., high Sr/Y and La/Yb ratios), subduction signatures (e.g., enriched Cs, Rb, Ba and depleted Nb, Ta, Ti), positive zircon εHf(t) values (1-6) and variable 208Pb/204Pb ratios (38.5-39.0), similar to other post-collisional porphyry intrusions in the Gangdese belt. Based on the above features, we propose that the Miocene porphyry intrusions at Jiru were generated by partial melting of subduction-modified lower crust. Well-developed negative Eu anomalies and low Sr/Y ratios (generally < 20) of the least fractionated samples of the Early Eocene granitoids indicate that water content of the primitive collision-related magma was < 4 wt.%, but increased to over 4 wt.% with fractional crystallization, as evidenced by very weak negative Eu anomalies and relatively high Sr/Y ratios (~ 40) for some samples with SiO2 contents of ~ 67 wt.%. Upper crustal differentiation, which would increase water content of residual magma, is thought to be a key step in the

  16. Spatial and seasonal distributions of frontal activity over the French continental shelf in the Bay of Biscay observed from satellite sea surface temperature

    NASA Astrophysics Data System (ADS)

    Yelekci, Ozge; Charrira, Guillaume; Capet, Xavier; Sudre, Joel; Yahia, Hussein

    2015-04-01

    Spatial and seasonal distributions, and development mechanisms of Sea Surface Temperature (SST) fronts (˜ 1-100 km) in vicinity of main French rivers, Gironde and Loire, over the continental shelf north of 45°N in the Bay of Biscay are explored. A dataset of 11 years' (2003 to 2013) remotely sensed SST by MODIS sensor onboard Aqua and Terra satellites has been investigated. This dataset has ˜1km spatial and daily temporal resolutions. Front detection is achieved through the Singularity Analysis (i.e. the process of calculating the degree of regularity or irregularity of a function at each point in a domain). The spatial distribution of front occurrence frequency is investigated seasonally. Seasonality of frontal activity in the Bay of Biscay is shown for the first time from the long-term satellite SST archive. The localized hot spots of higher frontal occurrences reveal important characteristics of the fine-scale dynamics including its possible drivers. We find that in winter, density fronts are prominent in a coastal strip where freshwater influence is important; in spring, this freshwater influence domain contrasts and reduces to estuaries while tidal fronts become apparent; in summer, tidal fronts in Ushant region and internal wave activity along shelf break dominates; in autumn, coastal density fronts due to freshwater inputs reappear as these inputs increase, and reduced stratification causes a weakening of the Ushant and shelf break fronts. Additional information and interpretations on the dynamics of these fronts is obtained from in situ observations and model outputs from operational oceanography.

  17. Bering Sea summary report: Outer Continental Shelf oil and gas activities in the Bering Sea and their onshore impacts

    SciTech Connect

    Deis, J.; Pierson, R.; Kurz, F.

    1983-09-01

    Two federal offshore oil-and-gas lease sales have been held in the Bering Sea Subregion. Lease Sale 57, Norton Basin, was held on March 15, 1983. Lease Sale 70, St. George Basin, was held on April 12, 1983. The sale offered 479 tracts, of which 97 received bids. The Department of the Interior has indicated that it will accept 96 of the 97 high bids; however, to date, leases have not been awarded. The Department of the Interior was enjoined from issuing leases by the US District Court of Alaska because of possible impacts from postlease preliminary seismic activities on gray and right whales. In accordance with the Court's ruling, leases cannot be issued until the completion of a supplemental environmental impact statement, which is anticipated to occur in November 1983. Six lease offerings in the Bering Sea Subregion are scheduled through 1987. Six deep stratigraphic test wells are the only wells drilled to date in the Bering Sea Subregion. To date, oil companies have not submitted exploration plans for the Norton Basin Planning Area. Exploration in Norton Basin could begin in the summer of 1984, at the earliest. Exploration plans cannot be submitted for the St. George Basin Planning Area until the leases are awarded. At this time, various onshore areas are being considered as possible support bases for offshore oil-and-gas exploration. At this stage, before exploratory drilling has occurred and in the absence of a commercial discovery, plans for transporting petroleum from the Bering Sea to markets in the United States are unclear. The current estimates of risked resources for lands leased in Lease Sale 57, Norton Basin, are 33 million barrels of oil and 110 billion cubic feet of gas. Lease Sale 70, St. George Basin, estimates of risked resources for leased lands are 27 million barrels of oil and 310 billion cubic feet of gas. 55 references, 10 figures, 3 tables.

  18. Temporal patterns of deer-vehicle collisions consistent with deer activity pattern and density increase but not general accident risk.

    PubMed

    Hothorn, Torsten; Müller, Jörg; Held, Leonhard; Möst, Lisa; Mysterud, Atle

    2015-08-01

    The increasing number of deer-vehicle collisions (DVCs) across Europe during recent decades poses a serious threat to human health and animal welfare and increasing costs for society. DVCs are triggered by both a human-related and a deer-related component. Mitigation requires an understanding of the processes driving temporal and spatial collision patterns. Separating human-related from deer-related processes is important for identifying potentially effective countermeasures, but this has rarely been done. We analysed two time series of 341,655 DVCs involving roe deer and 854,659 non-deer-related accidents (non-DVCs) documented between 2002 and 2011. Nonparametric smoothing and temporal parametric modelling were used to estimate annual, seasonal, weekly and diurnal patterns in DVCs, non-DVCs and adjusted DVCs. As we had access to data on both DVCs and non-DVCs, we were able to disentangle the relative role of human-related and deer-related processes contributing to the overall temporal DVC pattern. We found clear evidence that variation in DVCs was mostly driven by deer-related and not human-related activity on annual, seasonal, weekly and diurnal scales. A very clear crepuscular activity pattern with high activity after sunset and around sunrise throughout the year was identified. Early spring and the mating season between mid-July and mid-August are typically periods of high roe deer activity, and as expected we found a high number of DVC during these periods, although these patterns differed tremendously during different phases of a day. The role of human activity was mainly reflected in fewer DVCs on weekends than on weekdays. Over the ten-year study period, we estimated that DVCs increased by 25%, whereas the number of non-DVCs decreased by 10%. Increasing deer densities are the most likely driver behind this rise in DVCs. Precise estimates of DVC patterns and their relationship to deer and human activity patterns allow implementation of specific mitigation

  19. Characteristics of Ion Activation and Collision Induced Dissociation Using Digital Ion Trap Technology.

    PubMed

    Xu, Fuxing; Dang, Qiankun; Dai, Xinhua; Fang, Xiang; Wang, Yuanyuan; Ding, Li; Ding, Chuan-Fan

    2016-08-01

    Collision induced dissociation (CID) is one of the most established techniques for tandem mass spectrometry analysis. The CID of mass selected ion could be realized by ion resonance excitation with a digital rectangular waveform. The method is simple, and highly efficient CID result could be obtained by optimizing the experimental parameters, such as digital waveform voltage, frequency, and q value. In this work, the relationship between ion trapping waveform voltage and frequency at preselected q value, the relationship between waveform frequency and the q value at certain ion trapping voltage for optimum CID efficiency were investigated. Experiment results showed that the max CID efficiency of precursor reserpine ions can be obtained at different trapping waveform voltage and frequency when q and β are different. Based on systematic experimental analysis, the optimum experimental conditions for high CID efficiency can be calculated at any selected β or q. By using digital ion trap technology, the CID process and efficient fragmentation of parent ions can be realized by simply changing the trapping waveform amplitude, frequency, and the β values in the digital ion trap mass spectrometry. The technology and method are simple. It has potential use in ion trap mass spectrometry. Graphical Abstract ᅟ. PMID:27150507

  20. Characteristics of Ion Activation and Collision Induced Dissociation Using Digital Ion Trap Technology

    NASA Astrophysics Data System (ADS)

    Xu, Fuxing; Dang, Qiankun; Dai, Xinhua; Fang, Xiang; Wang, Yuanyuan; Ding, Li; Ding, Chuan-Fan

    2016-08-01

    Collision induced dissociation (CID) is one of the most established techniques for tandem mass spectrometry analysis. The CID of mass selected ion could be realized by ion resonance excitation with a digital rectangular waveform. The method is simple, and highly efficient CID result could be obtained by optimizing the experimental parameters, such as digital waveform voltage, frequency, and q value. In this work, the relationship between ion trapping waveform voltage and frequency at preselected q value, the relationship between waveform frequency and the q value at certain ion trapping voltage for optimum CID efficiency were investigated. Experiment results showed that the max CID efficiency of precursor reserpine ions can be obtained at different trapping waveform voltage and frequency when q and β are different. Based on systematic experimental analysis, the optimum experimental conditions for high CID efficiency can be calculated at any selected β or q. By using digital ion trap technology, the CID process and efficient fragmentation of parent ions can be realized by simply changing the trapping waveform amplitude, frequency, and the β values in the digital ion trap mass spectrometry. The technology and method are simple. It has potential use in ion trap mass spectrometry.

  1. Characteristics of Ion Activation and Collision Induced Dissociation Using Digital Ion Trap Technology

    NASA Astrophysics Data System (ADS)

    Xu, Fuxing; Dang, Qiankun; Dai, Xinhua; Fang, Xiang; Wang, Yuanyuan; Ding, Li; Ding, Chuan-Fan

    2016-05-01

    Collision induced dissociation (CID) is one of the most established techniques for tandem mass spectrometry analysis. The CID of mass selected ion could be realized by ion resonance excitation with a digital rectangular waveform. The method is simple, and highly efficient CID result could be obtained by optimizing the experimental parameters, such as digital waveform voltage, frequency, and q value. In this work, the relationship between ion trapping waveform voltage and frequency at preselected q value, the relationship between waveform frequency and the q value at certain ion trapping voltage for optimum CID efficiency were investigated. Experiment results showed that the max CID efficiency of precursor reserpine ions can be obtained at different trapping waveform voltage and frequency when q and β are different. Based on systematic experimental analysis, the optimum experimental conditions for high CID efficiency can be calculated at any selected β or q. By using digital ion trap technology, the CID process and efficient fragmentation of parent ions can be realized by simply changing the trapping waveform amplitude, frequency, and the β values in the digital ion trap mass spectrometry. The technology and method are simple. It has potential use in ion trap mass spectrometry.

  2. Relamination and the Differentiation of Continental Crust

    NASA Astrophysics Data System (ADS)

    Hacker, B. R.; Kelemen, P. B.; Behn, M. D.

    2014-12-01

    Most immature crust must be refined to attain the composition of mature continental crust. This refining may take the form of weathering, delamination, or relamination. Although delamination and relamination both call upon gravity-driven separation of felsic rock into the crust and mafic rock into the mantle, delamination involves foundering of rock from the base of active magmatic arcs, whereas relamination involves the underplating/diapirism of subducted sediment, arc crust, and continent crust to the base of the crust in any convergence zone. Relamination may be more efficient than lower crustal foundering at generating large volumes of material with the major- and trace-element composition of continental crust, and may have operated rapidly enough to have refined the composition of the entire continental crust over the lifetime of Earth. If so, felsic rocks could form much of the lower crust, and the bulk continental crust may be more silica rich than generally considered. Seismic wavespeeds require that only ~10-20% of the lowermost 5-15 km of continental crust must be mafic; combined heat-flow and wavespeed constraints permit continental lower crust to have 50 to 65 wt% SiO2.

  3. Continental rift jumps

    NASA Astrophysics Data System (ADS)

    Wood, Charles A.

    1983-05-01

    Continental rift jumps, analogous to jumps of oceanic spreading ridges, are here proposed to be common. Good examples exist in Iceland and Afar (both transitional from ridge to rift jumps), West Africa (Benue Trough and Cameroon Volcanic Line), and Kenya. Indeed, the Kenya rift appears to have jumped c. 100 km eastward c. 10 m.y. ago and is currently jumping further to the east. Possible jumps exist in the Baikal rift, the Limagne-Bresse rift pair, and parallel to ancient continental margins (e.g., the Triassic basins of the eastern U.S. to Baltimore Canyon and Georges Bank). Continental rifts jump distances that are approximately equal to local lithosphere thickness, suggesting that jumped rifts are controlled by lithosphere fracturing, but there appears to be no reason for the fracturing except migration of hot spots.

  4. Cooling history of the Upper Cretaceous Palgongsan Granite, Gyeongsang Basin, SE Korea and its tectonic implication for uplift on the active continental margin

    NASA Astrophysics Data System (ADS)

    Lim, Hyoun Soo; Lee, Yong Il

    2005-07-01

    Apatite and zircon fission track analyses were carried out to reconstruct the cooling and inferred uplift history of the Cretaceous Palgongsan Granite, Gyeongsang Basin, Korea. The Palgongsan Granite is one of the Bulguksa intrusive rocks that formed by arc-related plutonism during Late Cretaceous to Early Tertiary time. Fission track dating of the Palgongsan Granite yielded nearly concordant ages of 53 and 65 Ma for apatite and zircon, respectively. The Palgongsan Granite also shows a simple cooling pattern, which suggests that it has not been affected by any thermal event after emplacement. The cooling history derived from fission track data combined with other thermochronometric data indicates that the Palgongsan Granite experienced relatively rapid cooling in earlier stage (> 30 °C/Ma). The initial rapid cooling rate during the Late Cretaceous has been caused by the large thermal contrast between the granite body and the country rocks. After reaching thermal equilibrium with the surrounding country rocks, the cooling rate of the Palgongsan Granite was abruptly decreased in late stage. In this late stage, the decelerated cooling rate is interpreted to have been controlled by uplift and erosion processes, and the average exhumation rate is calculated to be ca. 50 m/my over the temperature range from 100 °C to the surface temperature. The cooling history of the Palgongsan Granite is in good agreement with that of the Ryoke Granitic Belt in Southwest Japan, as well as those of the Taebaeksan Range and other Bulguksa intrusive rocks in the Gyeongsang Basin. This suggests that such cooling was probably caused by regional uplift and exhumation processes on the East Asian active continental margin. Compared with the uplift rates of the Andes, the uplift rates on the eastern Pacific margin appear to be higher than those on the western Pacific margin.

  5. Linear Collisions

    ERIC Educational Resources Information Center

    Walkiewicz, T. A.; Newby, N. D., Jr.

    1972-01-01

    A discussion of linear collisions between two or three objects is related to a junior-level course in analytical mechanics. The theoretical discussion uses a geometrical approach that treats elastic and inelastic collisions from a unified point of view. Experiments with a linear air track are described. (Author/TS)

  6. Comparing the effects of rheology on the dynamics and topography of 3D subduction-collision models

    NASA Astrophysics Data System (ADS)

    Pusok, Adina E.; Kaus, Boris; Popov, Anton

    2015-04-01

    Most of the major mountain belts and orogenic plateaus are found within the overlying plate of active or fossil subduction and/or collision zones. It is well known that they evolve differently from one another as the result of specific combinations of surface and mantle processes. The differences among the structures and evolutions of mountain belts arise for several reasons, such as different strengths of materials, different amounts of regional isostatic compensation, and different mechanisms by which forces are applied to the convergence plates. All these possible controlling factors can change with space and time. Of all the mountain belts and orogenic plateaus, the most striking example is the India-Asia collision zone, which gave rise to the Himalayas and the Tibetan Plateau, the largest region of elevated topography and anomalously thick crust on Earth. Understanding the formation and evolution of such a highly elevated region has been the focus of many tectonic and numerical models. While some of these models (i.e. thin sheet model) have successfully illustrated some of the basic physics of continental collision, none can simultaneously represent active processes such as subduction, underthrusting, channel flow or extrusion, for which fully 3D models are required. Here, we employed the 3D code LaMEM to investigate the role that subduction, continental collision and indentation play on lithosphere dynamics at convergent margins, and the implications they have for the Asian tectonics. Our model setup resembles a simplified tectonic map of the India-Asia collision zone and we performed long-term 3D simulations to analyse the dynamics and the conditions under which large topographic plateaus, such as the Tibetan Plateau can form in an integrated lithospheric and upper-mantle scale model. Results of models with linear viscous rheologies show different modes between the oceanic subduction side (continuous subduction, trench retreat and slab roll-back) and the

  7. Continental magnetic anomaly constraints on continental reconstruction

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Crustal magnetic anomalies mapped by the MAGSAT satellite for North and South America, Europe, Africa, India, Australia and Antarctica and adjacent marine areas were adjusted to a common elevation of 400 km and differentially reduced to the radial pole of intensity 60,000 nT. These radially polarized anomalies are normalized for differential inclination, declination and intensity effects of the geomagnetic field, so that in principle they directly reflected the geometric and magnetic polarization attributes of sources which include regional petrologic variations of the crust and upper mantle, and crustal thickness and thermal perturbations. Continental anomalies demonstrate remarkably detailed correlation of regional magnetic sources across rifted margins when plotted on a reconstruction of Pangea. Accordingly, they suggest further fundamental constraints on the geologic evolution of the continents and their reconstructions.

  8. The Continental Crust.

    ERIC Educational Resources Information Center

    Burchfiel, B. Clark

    1983-01-01

    Continental crust underlies the continents, their margins, and also small shallow regions in oceans. The nature of the crust (much older than oceanic crust) and its dynamics are discussed. Research related to and effects of tectonics, volcanism, erosion, and sedimentation on the crust are considered. (JN)

  9. Continental Flood Basalts

    NASA Astrophysics Data System (ADS)

    Continental flood basalts have been receiving considerable scientific attention lately. Recent publications have focused on several particular flood-basalt provinces (Brito-Arctic, Karoo, Parana', Deccan, and Columbia Plateau), and much attention has been given to the proposed connection between flood-basalt volcanism, bolide impacts, and mass extinctions. The editor of Continental Flood Basalts, J. D. Macdougall, conceived the book to assemble in a single volume, from a vast and scattered literature, an overview of each major post-Cambrian flood-basalt province.Continental Flood Basalts has 10 chapters; nine treat individual flood-basalt provinces, and a summary chapter compares and contrasts continental flood-basalts and mid-oceanic ridge basalts. Specifically, the chapters address the Columbia River basalt, the northwest United States including the Columbia River basalt, the Ethiopian Province, the North Atlantic Tertiary Province, the Deccan Traps, the Parana' Basin, the Karoo Province, the Siberian Platform, and Cenozoic basaltic rocks in eastern China. Each chapter is written by one or more individuals with an extensive background in the province.

  10. Continental drift before 1900.

    PubMed

    Rupke, N A

    1970-07-25

    The idea that Francis Bacon and other seventeenth and eighteenth century thinkers first conceived the notion of continental drift does not stand up to close scrutiny. The few authors who expressed the idea viewed the process as a catastrophic event. PMID:16057953

  11. Activated Ion ETD Performed in a Modified Collision Cell on a Hybrid QLT-Oribtrap Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Ledvina, Aaron R.; Rose, Christopher M.; McAlister, Graeme C.; Syka, John E. P.; Westphall, Michael S.; Griep-Raming, Jens; Schwartz, Jae C.; Coon, Joshua J.

    2013-11-01

    We describe the implementation and characterization of activated ion electron transfer dissociation (AI-ETD) on a hybrid QLT-Orbitrap mass spectrometer. AI-ETD was performed using a collision cell that was modified to enable ETD reactions, in addition to normal collisional activation. The instrument manifold was modified to enable irradiation of ions along the axis of this modified cell with IR photons from a CO2 laser. Laser power settings were optimized for both charge (z) and mass to charge ( m/z) and the instrument control firmware was updated to allow for automated adjustments to the level of irradiation. This implementation of AI-ETD yielded 1.6-fold more unique identifications than ETD in an nLC-MS/MS analysis of tryptic yeast peptides. Furthermore, we investigated the application of AI-ETD on large scale analysis of phosphopeptides, where laser power aids ETD, but can produce b- and y-type ions because of the phosphoryl moiety's high IR adsorption. nLC-MS/MS analysis of phosphopeptides derived from human embryonic stem cells using AI-ETD yielded 2.4-fold more unique identifications than ETD alone, demonstrating a promising advance in ETD sequencing of PTM containing peptides.

  12. Distribution of fault activity in the early stages of continental breakup: an analysis of faults and volcanic products of the Natron Basin, East African Rift, Tanzania

    NASA Astrophysics Data System (ADS)

    Muirhead, J. D.; Kattenhorn, S. A.

    2012-12-01

    Recent magmatic-tectonic crises in Ethiopia (e.g. 2005 Dabbahu rifting episode, Afar) have informed our understanding of the spatial and temporal distribution of strain in magmatic rifts transitioning to sea-floor spreading. However, the evolving contributions of magmatic and tectonic processes during the initial stages of rifting, is a subject of ongoing debate. The <5 Ma northern Tanzania and southern Kenya sectors of the East Africa Rift provide ideal locations to address this problem. We present preliminary findings from an investigation of fault structures utilizing aerial photography and satellite imagery of the ~35 km wide Natron rift-basin in northern Tanzania. Broad-scale structural mapping will be supplemented by field observations and 40Ar-39Ar dating of lava flows cut by faults to address three major aspects of magma-assisted rifting: (1) the relative timing of activity between the border fault and smaller faults distributed across the width of the rift; (2) time-averaged slip rates along rift-zone faults; and (3) the spatial distribution of faults and volcanic products, and their relative contributions to strain accommodation. Preliminary field observations suggest that the ~500 m high border fault system along the western edge of the Natron basin is either inactive or has experienced a reduced slip rate and higher recurrence interval between surface-breaking events, as evidence by a lack of recent surface-rupture along the main fault escarpments. An exception is an isolated, ~2 km-long segment of the Natron border fault, which is located in close proximity (< 5km) to the active Oldoinyo Lengai volcano. Here, ~10 m of seemingly recent throw is observed in volcaniclastic deposits. The proximity of the fault segment to Oldoinyo Lengai volcano and the localized distribution of fault-slip are consistent with magma-assisted faulting. Faults observed within the Natron basin and on the flanks of Gelai volcano, located on the eastern side of the rift, have

  13. U-series, SrNdPb isotope and trace-element systematics across an active island arc-continent collision zone: Implications for element transfer at the slab-wedge interface

    NASA Astrophysics Data System (ADS)

    Hoogewerff, J. A.; Van Bergen, M. J.; Vroon, P. Z.; Hertogen, J.; Wordel, R.; Sneyers, A.; Nasution, A.; Varekamp, J. C.; Moens, H. L. E.; Mouchel, D.

    1997-03-01

    We present U-series, SrNdz.sbnd;Pb isotope and trace-element results of a regional study of geochemical systematics across an island arc-continent collision zone in the East Sunda Arc of Indonesia. Samples from four active volcanoes exhibit a striking compositional range from low-K tholeiitic to ultrapotassic, but all are characterised by high 87Sr/86Sr (0.7053-0.7067), radiogenic lead isotope ratios ( 206Pb/204Pb = 18.99-19.15), low ( 230Th) /( 232Thz) (0.66-0.85), and low 143Nd/144Nd (0.51255-0.51272), except for high 143Nd/144Nd (>0.51286) at the volcanic front. Low ( 230Th) /( 232Th) ratios are also found in terrigenous sediments in front of the arc, which, in combination with Srz.sbnd;Ndz.sbnd;Pb isotopic constraints, indicates that subducted continental material contributes to magma sources in this arc sector. The volcanoes close to the trench show a large excess of 238U over . 230Th (up to 80%) and of 226Ra over 230Th (up to 800%). In addition, they are enriched in elements thought to be mobile in hydrous fluids during slab-wedge transfer, such as Ba, Pb, and Sr. In contrast, Uz.sbnd;Thz.sbnd;Ra systematics are close to equilibrium in the volcanoes behind the front. Abundance patterns of incompatible trace elements in these rocks are similar to those of the terrigenous sediments, so that, in comparison with the arc-front lavas, they possess low Ba/La, Ba/Th, La/Th, Pb/Ce, and Zr/Nb. Higher concentration levels and less interelement fractionation form conspicuous differences with the front volcanics. Our combined isotopic and trace element data are consistent with three-component mixing whereby a slab-derived hydrous fluid and a siliceous melt are both added to the sub-arc mantle source. The hydrous fluid largely controls the input in the shallow part of the subduction zone, whereas the siliceous melt dominates the flux at deeper levels. Sedimentary material is considered to be the primary source of both. The large U-Th-Ra disequilibria at the front

  14. Suggested management guidelines for participation in collision activities with congenital, developmental, or postinjury lesions involving the cervical spine.

    PubMed

    Torg, J S; Ramsey-Emrhein, J A

    1997-07-01

    Many conditions involving the cervical spine in the athlete require a management decision. The purpose of this paper is to present appropriate guidelines for return to collision activities in those with congenital, developmental, or post-injury lesions. Information compiled from over 1200 cervical spine lesions documented by the National Football Head & Neck Injury Registry, an extensive literature review, as well as an understanding of injury mechanisms have resulted in reasonable management guidelines. Each of the congenital, developmental, and post-traumatic conditions presented are determined to present either no contraindication, relative contraindication, or an absolute contraindication on the basis of a variety of parameters. Conditions included in the discussion are: odontoid anomalies; spina bifida occulta; atlanto-occipital fusion; Klipple-Feil anomalies; cervical canal stenosis; spear tackler's spine; and traumatic conditions of the upper, middle, and lower cervical spine, including ligamentous injuries and fractures, intervertebral disc injuries, and post-cervical spine fusion. Emphasized is the fact that the proposed guidelines should be used in the decision-making process in conjuction with other factors such as the age, experience, ability of the individual, level of participation, position played, as well as the attitude and desires of the athlete and his parents after an informed discussion of the problem with particular regard to potential risk. PMID:9247923

  15. Decadal to millennial deformation in the Pamir - Tian Shan collision zone, NW China and surface expression of active tectonics

    NASA Astrophysics Data System (ADS)

    Bufe, A.; Bookhagen, B.; Burbank, D. W.; Bekaert, D. P.; Hussain, E.

    2013-12-01

    The collision between the Pamir and the Tian Shan is a type example of intracontinental collision. GPS studies show that in Northwest China, at the junction between the Tarim basin, the Pamir and the Tian Shan, 7-9 mm/y of north-south shortening are presently accommodated across the boundary between the two orogens. Here, the deformation has mostly stepped out from the high mountain front into the foreland and has formed a complex array of compressional structures. We compare rates of decadal deformation in the area with 104- to 106-year estimates and investigate the extent to which stream profiles and topography reflect the active tectonics in this setting. A dataset of decadal deformation rates around the Tarim-Tian Shan-Pamir junction in Northwest China is obtained from Interferometric Synthetic Aperture Radar (InSAR) time-series analysis. We use the StaMPS/MTI package to combine small-baseline and persistent-scatterer techniques and obtain results that show no significant residual topographic phase correlation. Our data show that deformation has stepped away from the high mountain front and is concentrated on a few structures in the foreland of the Pamir and Tian Shan. Line-of-sight deformation of up to 2-4 mm/y on the Pamir Frontal Thrust (PFT) and the Kashi detachment anticline are observed. No significant displacement of the Main Pamir Thrust can be detected. Within error, the modern deformation rates agree with previously published millennial to million-year estimates along the PFT. However, decadal deformation rates deviate from million-year shortening and rock-uplift rates of anticlines in the foreland of the Tian Shan. It remains unclear whether the discrepancy arises from a recent change to a new persistent uplift rate, or merely from short timescale fluctuation of uplift rate, for example within an earthquake cycle. In an additional step, we extract stream profiles and normalized steepness index (ksn) values for rivers with drainage areas larger than 9

  16. Deep crust and mantle structure linked to subduction of the Pacific plate at a continental margin from an active seismic source study

    NASA Astrophysics Data System (ADS)

    Stern, T. A.; Okaya, D. A.; Henrys, S. A.; Savage, M. K.; Sato, H.; Iwasaki, T.

    2013-12-01

    We present new results that bear on mantle structure in a subduction zone of both the down going and over-riding plates. Wellington region, New Zealand, sits on the Australian plate a mere ~ 15-25 km above the subducted Pacific plate. This is rare: most active continental margins have at least 30-50 km of free board above subduction zones (cf, Pacific NW, Honshu). Such a shallow setting offers unusually good conditions for making terrestrial observations of the subduction process. In 2010-11 an active source seismic experiment (SAHKE) was carried out across the Wellington region. Both active and passive seismic methods were used to establish a model of the crustal structure and upper mantle structure beneath SAHKE (Henrys et al , 2013). We recorded 12 x 500 kg dynamite shots on ~ 1000 recorders place at 100 m spacing from coast to coast. These data contain excellent returns from the subduction zone at two-way travel times of 7-15 s, but we also recorded coherent reflection energy down to 30 s two-way-travel-time on vertical recorders and 47 s on horizontal recorders. We performed a low-fold stack of these deep reflections and see two zones. The deepest reflections define a westward 17 degree-dipping zone at ~ 100 km deep that is possibly the base of the subducted Pacific plate. The westward dip on this 100 km deep reflector matches that for the top of the plate. Moreover, the total plate thickness implied is ~ 80 km, which matches that predicted for 100 my old oceanic lithosphere. The other deep reflection zone dips eastward across the shot gathers and is typically seen at two-way travel times of 18-25 s on the vertical phones. We also see the same event as a Vs arrival on horizontal phones at two-way travel times of 34-47s. When migrated these reflections define an east dipping reflector that is within the mantle of the overriding Australian plate, and the surface projection of the reflector is ~ 80 km west of SAHKE line. This finding raises the question of what

  17. Importance of continental subductions for the growth of the Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Guillot, Stephane; Replumaz, Anne; Riel, Nicolas; Hetenyi, Gyorgy

    2013-04-01

    How and when the Tibetan plateau developed has long been a puzzling question with implications for the current understanding of the behaviour of the continental lithosphere in convergent zones. Tibet initially resulted from the accretion of the Gondwana continental blocks to the southern Asian margin during the Palaeozoic and Mesozoic eras. These successive accretions have potentially favoured the creation of local landforms, particularly in southern Tibet, but no evidence exists in favour of the existence of a proto-Tibetan plateau prior to the Cenozoic. Moreover, before the India-Asia collision, the Tibetan crust had to be sufficiently cold and rigid to transfer the horizontal forces from India to northern Tibet and localize the deformation along the major strike-slip faults. However, these successive accretions associated with subductions have contaminated the Tibetan lithospheric mantle and largely explain the potassium- and sodium-rich Cenozoic magmatism. Another consequence of this contamination by fluids is the softening of the Tibetan lithosphere, which favoured intra-continental subductions. The timing and the geochemical signatures of the magmatism and the palaeo-altitudes suggest the early growth of the Tibetan plateau. By the Eocene, the southern plateau and the northern portion of Himalaya would be at an altitude of approximately 4000 meters, while the central and northern Tibetan plateau was at altitudes of approximately 2000 to 3000 meters at the Eocene-Oligocene transition. From all of these data, we propose a model of the formation of the Tibetan plateau coupled with the formation of Himalaya, which accounts for more than 2000 km of convergence accommodated by the deformation of the continental lithospheres. During the early Eocene (55-45 Ma), the continental subduction of the high-strength Indian continental lithosphere dominates, ending with the detachment of the Indian slab. Between 45 and 35 Ma, the continental collision is established

  18. EFFECT OF ION-NEUTRAL COLLISIONS IN SIMULATIONS OF EMERGING ACTIVE REGIONS

    SciTech Connect

    Leake, James E.; Linton, Mark G.

    2013-02-10

    We present results of 2.5D numerical simulations of the emergence of sub-surface magnetic flux into the solar atmosphere, with emerging flux regions ranging from 10{sup 18} to 10{sup 21} Mx, representing both ephemeral and active regions. We include the presence of neutral hydrogen in the governing equations, improve upon previous models by including the ionization in the equation of state, and use a more realistic convection zone model. We find that ionization and recombination of plasma during the rise of a convection zone flux tube reduces the rise speed of the tube's axis. The presence of neutral hydrogen allows the effective flow of mass across field lines, by the addition of a Pedersen resistivity to the generalized Ohm's law, which dissipates current perpendicular to the magnetic field. This causes an increase of up to 10% in the amount of magnetic in-plane flux supplied to the corona and a reduction of up to 89% in the amount of sub-surface plasma brought up into the corona. However, it also reduces the amount of free magnetic energy supplied to the corona, and thus does not positively affect the likelihood of creating unstable coronal structures.

  19. The Brazilian continental margin

    NASA Astrophysics Data System (ADS)

    Martins, L. R.; Coutinho, P. N.

    1981-04-01

    The Brazilian continental margin, with its interesting morphology, structure and sediments, has become better known only during the last two decades. Six physiographical provinces can be recognized at the continental margin and the adjacent coast: (1) Cabo Orange-Parnaiba delta; (2) Parnaiba delta-Cabo Sa˜o Roque; (3) Cabo Sa˜o Roque-Belmonte; (4) Belmonte-Cabo Frio; (5) Cabo Frio-Cabo Santa Marta; and (6) Cabo Santa Marta-Chui. The shelf is rather wide near the Amazon Mouth, becoming narrower eastwards, continuing very narrow along the northeastern and eastern coast, and becoming wider again in the south towards the Plate River. Prominent morphological features along the margin are the Amazon cone, the marginal plateaus off northeastern Brazil, the Sa˜o Francisco cone and canyon, the Abrolhos Bank, and the deep-sea plateaus of Pernambuco and Sa˜o Paulo. On the shelf proper a number of relief elements exist, such as sand waves east of the Amazon, submarine terraces at various places, and irregularities of structural origin. The shelf break is rather smooth in the far north and south, more abrupt in the remainder. Surface sediments of the Brazilian shelf show five distinct facies types: littoral quartz sands, mud, transition sand-mud, coralline algae, and biodetrital. The terrigenous elastic fractions dominate off the Amazon and in southern Brazil; between these areas they occupy a very narrow strip near the coast. The carbonate facies, predominantly composed of calcareous algae, is abundant between the Parnaiba delta and Cabo Frio; to the south this facies is more biodetrital and restricted to the outer shelf. Economically important on the Brazilian continental margin besides oil, are sands and gravels, carbonate deposits, evaporites and some subsurface coal. Other possible mineral resources could be phosphate, heavy minerals and clays for ceramics.

  20. India-Eurasia collision triggers formation of an oceanic microplate

    NASA Astrophysics Data System (ADS)

    Matthews, Kara; Müller, Dietmar; Sandwell, David

    2016-04-01

    Detailed mapping of seafloor tectonic fabric in the Indian Ocean, using high-resolution satellite-derived vertical gravity gradient data, reveals an extinct Pacific-style oceanic microplate - the Mammerickx Microplate - west of the Ninetyeast Ridge. It is one of the first Pacific-style microplates to be mapped outside the Pacific basin, suggesting that geophysical conditions during formation probably resembled those that have dominated at eastern Pacific ridges. The microplate formed at the Indian-Antarctic ridge and is bordered by an extinct ridge in the north and pseudofault in the south, whose conjugate is located north of the Kerguelen Plateau. Independent microplate rotation is indicated by asymmetric pseudofaults and rotated abyssal hill fabric, also identified in multibeam data. Magnetic anomaly picks and age estimates calculated from published spreading rates suggest formation during chron 21o (~47.3 Ma). Plate reorganizations can trigger ridge propagation and microplate development, and we propose that formation of the Mammerickx Microplate is linked with the initial 'soft' stage of the India-Eurasia collision. The collision altered the stress regime at the Indian-Antarctic ridge, leading to a change in segmentation and ridge propagation from an establishing transform fault. Fast Indian-Antarctic spreading that preceded microplate formation, and Kerguelen Plume activity may have facilitated ridge propagation via the production of thin and weak lithosphere. However, both factors had been present for tens of millions of years and are therefore unlikely to have triggered the event. Prior to the collision, this combination of fast spreading and plume activity was responsible for the production of a wide region of undulate seafloor to the north of the extinct ridge and 'W' shaped lineations that record back and forth ridge propagation. Microplate formation provides a means of dating the onset of the India-Eurasia collision, and is completely independent of and

  1. Converting your Continental

    SciTech Connect

    Wirz, B.M.

    1981-07-01

    Inflation and higher fuel and environmental costs make conventional-generated power as unaffordable (as a Lincoln Continental in the automobile market) for retail and industrial customers, many of whom are looking for alternatives to purchase electric power. The loss of revenue from competing energy sources eliminates the monopoly status that utilities have enjoyed and is forcing utilities to provide what customers want and do it better than the competition. Utilities have only research and development or fuel switching to improve efficiency unless they rethink their approach and come up with new alternatives. 1 table. (DCK)

  2. 76 FR 2254 - Notice of Arrival on the Outer Continental Shelf

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ... Arrival (NOA) on the Outer Continental Shelf in the Federal Register (74 FR 29439). We received two sets... established on March 4, 1982, as part of a final rule entitled, Outer Continental Shelf Activities (47 FR 9366... SECURITY Coast Guard 33 CFR Part 146 RIN 1625-AB28 Notice of Arrival on the Outer Continental Shelf...

  3. Differentiation of Regioisomeric Aromatic Ketocarboxylic Acids by Positive Mode Atmospheric Pressure Chemical Ionization Collision-Activated Dissociation Tandem Mass Spectrometry in a Linear Quadrupole Ion Trap Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Amundson, Lucas M.; Owen, Benjamin C.; Gallardo, Vanessa A.; Habicht, Steven C.; Fu, Mingkun; Shea, Ryan C.; Mossman, Allen B.; Kenttämaa, Hilkka I.

    2011-04-01

    Positive-mode atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS n ) was tested for the differentiation of regioisomeric aromatic ketocarboxylic acids. Each analyte forms exclusively an abundant protonated molecule upon ionization via positive-mode APCI in a commercial linear quadrupole ion trap (LQIT) mass spectrometer. Energy-resolved collision-activated dissociation (CAD) experiments carried out on the protonated analytes revealed fragmentation patterns that varied based on the location of the functional groups. Unambiguous differentiation between the regioisomers was achieved in each case by observing different fragmentation patterns, different relative abundances of ion-molecule reaction products, or different relative abundances of fragment ions formed at different collision energies. The mechanisms of some of the reactions were examined by H/D exchange reactions and molecular orbital calculations.

  4. In situ zircon U-Pb and Hf-O isotopic results for ca. 73 Ma granite in Hainan Island: Implications for the termination of an Andean-type active continental margin in southeast China

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao-Yan; Li, Xian-Hua

    2014-03-01

    We report in the paper integrated analyses of in situ zircon U-Pb ages, Hf-O isotopes, whole-rock geochemistry and Sr-Nd isotopes for the Longlou granite in northern Hainan Island, southeast China. SIMS zircon U-Pb dating results yield a crystallization age of ˜73 Ma for the Longlou granite, which is the youngest granite recognized in southeast China. The granite rocks are characterized by high SiO2 and K2O, weakly peraluminous (A/CNK = 1.04-1.10), depletion in Sr, Ba and high field strength elements (HFSE) and enrichment in LREE and large ion lithophile elements (LILE). Chemical variations of the granite are dominated by fractional crystallization of feldspar, biotite, Ti-Fe oxides and apatite. Their whole-rock initial 87Sr/86Sr ratios (0.7073-0.7107) and ɛNd(t) (-4.6 to -6.6) and zircon ɛHf(t) (-5.0 to 0.8) values are broadly consistent with those of the Late Mesozoic granites in southeast China coast. Zircon δ18O values of 6.9-8.3‰ suggest insignificant involvement of supracrustal materials in the granites. These granites are likely generated by partial melting of medium- to high-K basaltic rocks in an active continental margin related to subduction of the Pacific plate. The ca. 73 Ma Longlou granite is broadly coeval with the Campanian (ca. 80-70 Ma) granitoid rocks in southwest Japan and South Korea, indicating that they might be formed along a common Andean-type active continental margin of east-southeast Asia. Tectonic transition from the Andean-type to the West Pacific-type continental margin of southeast China likely took place at ca.70 Ma, rather than ca. 90-85 Ma as previously thought.

  5. Continental Lower Crust: Wavespeeds, Composition, and Relamination

    NASA Astrophysics Data System (ADS)

    Hacker, B. R.; Kelemen, P. B.; Behn, M. D.

    2015-12-01

    The composition of much of Earth's lower continental crust is enigmatic. The available heat-flow and wavespeed constraints can be satisfied if lower continental crust elsewhere contains anywhere from 49 to 62 wt% SiO2 (similar to andesite and dacite), with high to moderate concentrations of K, Th and U. Beneath shields and platforms, Vp suggests that 20-30% of lower crust is mafic. A large fraction of this material could be denser than peridotite. In these settings the underlying upper mantle is too cold to permit development of a convective instability. High Vp lithologies in these settings may be the result of mafic underplating, or slow metamorphic growth of large proportions of garnet. Vp from lower crust of Paleozoic-Mesozoic orogens indicates a smaller amount of mafic rock and little or no material that is denser than peridotite. Beneath rifts, arcs, and volcanic plateaux and beneath continent-collision zones, ~10-20% of lower crust is mafic, and about half that is denser than peridotite. The inferred gravitational instability and high Moho temperatures suggest that the mafic lower crust in these regions may be temporary. During sediment subduction, subduction erosion, arc subduction, and continent subduction, mafic rocks become eclogite and may continue to descend into the mantle, whereas more silica-rich rocks are transformed into felsic gneisses that are less dense than peridotite but more dense than continental upper crust. These more-felsic rocks may rise buoyantly, undergo decompression melting and melt extraction, and may be relaminated to the base of the crust. As a result of this refining/differentiation process, such relatively felsic rocks could form much of lower crust.

  6. Organic geochemistry of outer continental margins and deep ocean sediments

    SciTech Connect

    Whelan, J.K.

    1990-01-01

    This report discusses the activities and progress made in the study of continental margins and deep ocean sediments. Topics discussed are the calibration of thermal maturation markers, hydrous pyrolysis studies and sample collection. (KS)

  7. Earth's continental crustal gold endowment

    NASA Astrophysics Data System (ADS)

    Frimmel, H. E.

    2008-03-01

    The analysis of the temporal distribution of gold deposits, combined with gold production data as well as reserve and resource estimates for different genetic types of gold deposit, revealed that the bulk of the gold known to be concentrated in ore bodies was added to the continental crust during a giant Mesoarchaean gold event at a time (3 Ga) when the mantle temperature reached a maximum and the dominant style of tectonic movement changed from vertical, plume-related to subhorizontal plate tectonic. A magmatic derivation of the first generation of crustal gold from a relatively hot mantle that was characterized by a high degree of partial melting is inferred from the gold chemistry, specifically high Os contents. While a large proportion of that gold is still present in only marginally modified palaeoplacer deposits of the Mesoarchaean Witwatersrand Basin in South Africa, accounting for about 40% of all known gold, the remainder has been recycled repeatedly on a lithospheric scale, predominantly by plate-tectonically induced magmatic and hydrothermal fluid circulation, to produce the current variety of gold deposit types. Post-Archaean juvenile gold addition to the continental crust has been limited, but a mantle contribution to some of the largest orogenic or intrusion-related gold deposits is indicated, notably for the Late Palaeozoic Tien Shan gold province. Magmatic fluids in active plate margins seem to be the most effective transport medium for gold mobilization, giving rise to a large proportion of volcanic-arc related gold deposits. Due to their generally shallow crustal level of formation, they have a low preservation potential. In contrast, those gold deposits that form at greater depth are more widespread also in older rocks. This explains the high proportion of orogenic (including intrusion-related) gold (32%) amongst all known gold deposits. The overall proportion of gold concentrated in known ore bodies is only 7 × 10- 7 of the estimated total

  8. Incipient Crustal Stretching across AN Active Collision Belt: the Case of the Siculo-Calabrian Rift Zone (central Mediterranean)

    NASA Astrophysics Data System (ADS)

    Catalano, S.; Tortorici, G.; Romagnoli, G.; Pavano, F.

    2012-12-01

    In the Central Mediterranean, the differential roll-back of the subducting Nubia Plate caused the Neogene-Quaternary extrusion of the Calabrian arc onto the oceanic Ionian slab, and the opening of the oceanic Tyrrhenian Basin, in the overriding Eurasia Plate. The differential motion at the edges of the arc was largely accommodated along transform faults that propagated across the orogenic belt. Since the Late Quaternary, the southern edge of the arc has been replaced by the roughly N-S oriented Siculo-Calabrian Rift Zone (SCRZ) that formed as the NNW-directed normal faults of NE Sicily, crossing the orogenic belt, have linked the NNE-oriented Tyrrhenian margin of southern Calabria with the NNW-trending Africa-Ionian boundary of southeastern Sicily. Our study focused on the Sicily shoulder of the SCRZ, where the transition zone between the extensional belt and the still active Nubia-Eurasia convergent margin is characterized by two distinct mobile crustal wedges, both lying on an upwarped Mantle, where a re-orientations of the σ1 is combined with volcanism (e.g. Etna, Aeolian islands) and a huge tectonic uplift. In southeastern Sicily, the Hyblean-Etnean region evolved, since about 0.85 Ma, as an indipendent crustal wedge, moving towards the NNW and pointing to the active Mt. Etna volcano. A local ENE crustal stretching accompanied the traslation of the block and pre-dated the ESE-oriented extension governing the propagation of the southernmost branch of the SCR, which started at about 330 ka B.P.. Similarly, the Peloritani-Aeolian region, flanked by the 125 ka-old NE-Sicily branch of the rift zone, represents a mostly submerged crustal wedge that migrates towards the NE, diverging from the rest of the Sicily collision zone and pointing to the Stromboli volcano. The Peloritani-Aeolian block is characterized by the occurrence of a wide central NE-oriented collapsed basin contoured by an actively uplifting region, whose tectonic boundaries are evidenced by a sharp

  9. Reconstruction of multiple tectonic events in continental margins by integrated tectonostratigraphic and geochronological analysis: the Mesozoic to Paleogene Caribbean-South American interaction in northeastern Colombia

    NASA Astrophysics Data System (ADS)

    Cardona, Agustin; Montes, Camilo; Bayona, German; Valencia, Victor; Ramirez, Diego; Zapata, Sebastian; Lara, Mario; Lopez-Martinez, Margarita; Thomson, Stuart; Weber, Marion

    2013-04-01

    Although the older record and successive tectonic scenarios experienced by a continental margin is commonly fragmentary, integrated field, petrological and geochronological analysis can reconstruct the long term tectonic evolution of continental margins and characterized major controls on the orogenic style. We present new geochronological constraints from igneous and low to very low grade metasedimentary rocks from the Caribbean continental margin of northeastern Colombia (Guajira region) in order to reconstruct the different tectonic events recorded by the margin before, during and following the arc-continent collision with the front of the Caribbean plate. Zircon U-Pb LA-ICP-MS geochronology results from leucogranites associated with garnet amphibolites, tonalites and volcanic rocks that made the continental basement of northeastern Colombia reveals and Early to Middle Mesozoic tectonic activity with peaks at ca. 220-230 Ma and 170-180 Ma. This magmatic record is related to a collisional belt link to the final agglutination of Pangea and was followed by an overimposed far field back-arc setting associated to the subduction of the Pacific (Farrallon) plate under the Pangea supercontinent. Muscovite and biotite Ar-Ar geochronology from basement rocks and low grade Mesozoic metasediments also reveals the existence of Middle Jurassic to Early Cretaceous thermal events link to the final opening of the proto-Caribbean ocean. The South American continental margin was subsequently affected by an arc-continent collisional event with the front of the Caribbean plate. This event is recorded by the growth of a Banda-type collisional melange that mixed South American continental margin sediments with mafic and ultramafic blocks of intra-oceanic arc origin, the formation of a coherent metasedimentary belt also made of South American margin sediments, and the mylonitization of the continental basement. Ar-Ar temporal constraints on the low grade metasedimentary rocks and

  10. Cs-137 geochronology, epithermal neutron activation analysis, and principal component analysis of heavy metals pollution of the Black Sea anoxic continental shelf sediments

    NASA Astrophysics Data System (ADS)

    Duliu, O. G.; Cristache, C.; Oaie, G.; Culicov, O. A.; Frontasyeva, M. V.

    2009-04-01

    Anthropogenic Cs-137 Gamma-ray Spectroscopy assay (GrSA) performed at the National Institute of Research and Development for Physics and Nuclear Engineering - Bucharest (Romania) in correlation with Epithermal Neutrons Activation Analysis (ENAA) performed at the Joint Institute of Nuclear Researches - Dubna (Russia) were used to investigate a 50 cm core containing unconsolidated sediments collected at a depth of 600 m off Romanian town of Constantza, located in the anoxic zone of the Black Sea Continental Shelf. A digital radiography showed the presence of about 265 distinct laminae, 1 to 3 mm thick, a fact attesting a stationary sedimentary process, completely free of bioturbation. After being radiographed, the core was sliced into 45 segments whose thickness gradually increased from 0.5 to 5 cm, such that the minimum thickness corresponded to the upper part of the core. From each segment two aliquots of about 0.5 g and 50 g were extracted for subsequent ENAA and Cs-137 GrSA. The Cs-137 vertical profile evidenced two maxima, one of them was very sharp and localized at a depth of 1 cm and the other very broad, almost undistinguished at about 8 cm depth, the first one being attributed to 1986 Chernobyl accident. Based on these date, we have estimated a sedimentation ratio of about 0.5 mm/year, value taken as reference for further assessment of recent pollution history. By means of ENAA we have determined the vertical content of five presumed pollutants, e.i. Zn, As, Br, Sn and Sb and of Sc, as natural, nonpolluting element. In the first case, all five elements presented a more or less similar vertical profile consisting of an almost exponential decrease for the first 10 cm below sediment surface followed by a plateau until the core base, i.e. 50 cm below surface, dependency better described by the equation: c(z) = c0 [1+k exp (-z/Z)] (1) where: where c(z) represents the concentration vertical profile; z represents depth (in absolute value); c0 represents the plateau

  11. Tectonic evolution of forearc nappes of the active Banda arc-continent collision: Origin, age, metamorphic history and structure of the Lolotoi Complex, East Timor

    NASA Astrophysics Data System (ADS)

    Standley, Carl E.; Harris, Ron

    2009-12-01

    An integrated multidisciplinary investigation of the Lolotoi Complex of East Timor (Timor Leste) indicates that it is part of the Banda forearc that was metamorphosed and rapidly exhumed during the Eocene and accreted to the NW Australian continental margin during Late Miocene to present arc-continent collision. Greenschist, graphitic phyllite, quartz-mica schist, amphibolite and pelitic schist dominate metamorphic rock types. Mineral, whole rock, and trace element geochemical analyses of metabasites indicate protolith compositions consistent with tholeiitic basalt and basaltic andesite with mixed MORB and oceanic arc affinities. Metapelite schist is mostly composed of metasedimentary units derived from mafic to intermediate rocks with oceanic to continental volcanic arc provenance. Thermobarometric calculations show peak metamorphic conditions of 530 °C to 680 °C for garnet-biotite pairs and amphibole, and peak pressures of 5 to 10 kbar for garnet-aluminosilicate-quartz-plagioclase assemblages. Peak metamorphism occurred at 45.36 ± 0.63 Ma, as indicated by Lu-Hf analyses of garnet. Detrital zircon grains have a U/Pb age distribution with spikes at 663, 120 and 87 Ma, which is typical of detrital zircon ages throughout the Great Indonesian Arc of Asia, but is distinct from Australian affinity units. These data indicate deposition and later metamorphism occurred after 87 Ma. Structural analyses of the metamorphic rocks and their sedimentary and volcanic cover units reveals 5-6 deformational phases of alternating shortening and extension. There is little to no evidence of strike-slip deformation. Phases 1-4 are inferred as pre-Oligocene from age determinations. Phases 5 and 6 are most likely related to latest Miocene to Pliocene nappe emplacement and Pliocene to present collisional deformation. Kinematic indicators show mostly top to the SE directed shortening and top to the south and SE extension. Structural mapping indicates that the Lolotoi Complex and some of

  12. Influences of offshore activity. Hearing before the Subcommittee on Panama Canal/Outer Continental Shelf, of the House of Representatives, Ninety-Eighth Congress, First Session on offshore oil and gas activity and its socio-economic and environmental influences, October 12, 1983

    SciTech Connect

    Not Available

    1984-01-01

    A field hearing in Humble, Texas heard testimony on the socio-economic and environmental effects of Outer Continental Shelf oil and gas activity in the Gulf of Mexico. These activities influence the commercial and recreational climate of the area as well as municipal services. The 20 witnesses included representatives of the petroleum, shipping, fishing, and other industries, environmental groups, and both organizations and agencies concerned with coastal management. Additional material and communications supplied for the record follows the testimony.

  13. Magnetostratigraphic Record of the Early Evolution of the Southwestern Tian Shan Foreland Basin (Ulugqat Area), Interactions with Pamir Indentation and India-Asia Collision

    NASA Astrophysics Data System (ADS)

    Yang, W.; Wang, S.

    2015-12-01

    The Tian Shan range is an inherited intracontinental structure reactivated by the far-field effects of India-Asia collision. A growing body of thermochronology and magnetostratigraphy datasets shows the range grew through several tectonic pulses since ~25 Ma, however the early Cenozoic history remains poorly constrained. Particularly enigmatic is the time-lag between the Eocene India-Asia collision and the Miocene onset of Tian Shan exhumation. This peculiar period is potentially recorded along the southwestern Tian Shan piedmont. There, recently dated late Eocene marine deposits of the proto-Paratethys epicontinental sea transition to continental foreland basin sediments of unknown age. We provide magnetostratigraphic dating of these continental sediments from the 1700-m-thick Mine section integrated with previously published detrital apatite fission track and U/Pb zircon ages. The most likely correlation to the geomagnetic polarity time scale indicates an age span from 20.8 to 13.3 Ma with a marked accumulation rate increase at 19-18 Ma. This implies the entire Oligocene period is missing between the last marine and first continental sediments, as suggested by previous southwestern Tian Shan results. This differs from the southwestern Tarim basin where Eocene marine deposits are continuously overlain by late Eocene-Oligocene continental sediments. This supports a simple evolution model of the western Tarim basin with Eocene-Oligocene foreland basin activation to the south related to northward thrusting of the Kunlun Shan, followed by early Miocene activation of northern foreland basin related to overthrusting of the south Tian Shan. Our data also support southward propagation of the Tian Shan piedmont from 20-18 Ma that may relate to motion on the Talas Fergana Fault. The coeval activation of a major right-lateral strike-slip system allowing indentation of the Pamir Salient into the Tarim basin, suggest far-field deformation from the India-Asia collision zone

  14. Beaufort Sea monitoring program: analysis of trace metals and hydrocarbons from Outer Continental Shelf (OCS) activities. Final report, 1983-1986

    SciTech Connect

    Boehm, P.D.; Crecelius, E.; Steinhauer, W.; Steinhauer, M.; Tuckfield, C.

    1986-08-13

    An environmental-monitoring program, designed to detect and quantify long-term changes in sediment and tissue concentrations of metals and hydrocarbons potentially due to oil and gas exploration and development on the U.S. Beaufort Sea continental shelf, was initiated in 1984. In Year-1 of the three-year study, a series of benthic stations was established in the nearshore area between Barter Island and Cape Halkett. In Year-2 of the study, areal coverage of the Study Area was increased to 39 marine stations and 10 shoreline and river stations. Analysis of six replicate sediment samples for trace metals, and saturated and aromatic hydrocarbons revealed a wide range of concentrations. Both trace metal and hydrocarbon analyses of bivalve and crustacean tissues indicated concentrations differences between species but no apparent relationship between animal body burdens and sediment concentrations.

  15. Continental rifting - Progress and outlook

    NASA Technical Reports Server (NTRS)

    Baker, B. H.; Morgan, P.

    1981-01-01

    It is noted that in spite of the flood of new data on continental rifts in the last 15 years, there is little consensus about the basic mechanisms and causes of rifting. The remarkable similarities in rift cross sections (shown in a figure), are considered to suggest that the anomalous lithospheric structure of rifts is more dependent on lithosphere properties than the mode of rifting. It is thought that there is a spectrum of rifting processes for which two fundamental mechanisms can be postulated: an active mechanism, whereby thermal energy is transmitted into the lithosphere from the underlying asthenosphere, and a passive mechanism by which mechanical energy is transmitted laterally through the lithosphere as a consequence of plate interactions at a distance. In order to permit the concept of the two fundamentally different mechanisms to be tested, a tentative classification is proposed that divides rifts into two basic categories: active rifting and passive rifting. Here, the magnitude of active rifting will depend on the rate at which lithosphere moves over the thermal source, with rifts being restricted to stationary or slow-moving plates.

  16. Subduction-Driven Recycling of Continental Margin Lithosphere

    NASA Astrophysics Data System (ADS)

    Levander, A.; Bezada, M. J.; Niu, F.; Palomeras, I.; Thurner, S.; Humphreys, E.; Miller, M. S.; Carbonell, R.; Gallart, J.; Schmitz, M.

    2014-12-01

    While subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, recycling continental lithosphere appears far more complicated and is less well understood. Delamination and convective downwelling are two widely recognized processes invoked to explain the removal of lithospheric mantle under or adjacent to orogenic belts. Here we describe another process that can lead to the loss of continental lithosphere adjacent to a subduction zone: Subducting oceanic plates can entrain and recycle lithospheric mantle from an adjacent continent and disrupt the continental lithosphere far inland from the subduction zone. Seismic images from recent dense broadband arrays on opposite sides of the Atlantic show higher than expected volumes of positive anomalies identified as the subducted Atlantic (ATL) slab under northeastern South America (SA), and the Alboran slab beneath the Gibraltar arc region (GA). The positive anomalies lie under and are aligned with the continental margins at depths greater than 200 km. Closer to the surface we find that the continental margin lithospheric mantle is significantly thinner than expected beneath the orogens adjacent to the subduction zones. Thinner than expected lithosphere extends inland as far as the edges of nearby cratonic cores. These observations suggest that subducting oceanic plates viscously entrain and remove continental mantle lithosphere from beneath adjacent continental margins, modulating the surface tectonics and pre-conditioning the margins for further deformation. The latter can include delamination of the entire lithospheric mantle, as around GA, inferred by results from active and passive seismic experiments. Secondary downwellings develop under the continental interior inland from the subduction zone: We image one under SA and one or more in the past were likely under GA. The process of subduction-driven continental margin lithosphere removal reconciles numerous, sometimes mutually

  17. Tectonic Evolution of the Banda Arc-Continent Collision in the Timor Region

    NASA Astrophysics Data System (ADS)

    Harris, R. A.

    2011-12-01

    Recent detailed studies of the active Banda arc-continent collision reveal many new features about its tectonic evolution, such as (1) when collision initiated, (2) conditions and age of metamorphism, (3) timing of island emergence and exhumation, (4) how the arc is affected by collision, (5) differences between rock and surface uplift rates, (6) the temporal distribution of strain and (7) natural hazards. (1) The youngest Australian continental margin material incorporated into the Banda orogen is 7-8 Ma in East Timor and 6 Ma in West Timor. (2) Collision-related metamorphic rocks in East Timor yield max. temperatures of 850 °C and pressures of 12 kb. The age of the metamorphism is constrained by zircon U/Pb ages of 6.7 Ma. (3) Island emergence and erosional exhumation is constrained by foraminifera depth vs. age estimates of the transition from deep marine chalk to distal turbidite deposition at 4.2 Ma in East Timor and younger to the east and west. Exhumation of metamorphic rocks is constrained by amphibole with Ar/Ar cooling ages of ~6 Ma (~525°C), zircons with U/He ages of 4.5 Ma (215°C), and apatite with U/He ages of 3.5 Ma (90°C). Younger exhumation ages are found to the south. (4) Contamination of the volcanic arc by subducted continental material is first detected in eroded arc islands near East Timor at 5 Ma. The age of contamination youngs both east and west in less eroded, active arc islands. The main arc edifice north of East Timor is abandoned at 1-3 Ma and is shifted 30 km to the north by the Wetar backarc thrust. A new volcanic center emerges further north. (5) Coral terraces encrust the rising islands and yield highly variable uplift rates, with some as high as 1.5 mm/a. The highest rates correspond with active thrust faults and diapirs. Rock uplift rates associated with exhumation of the schist belt are as high as 8 mm/a. (6) GPS velocities in the most advanced part of the collision (central Timor) show that 70% of the 70 mm/a convergence

  18. Double subduction of continental lithosphere, a key to form wide plateau

    NASA Astrophysics Data System (ADS)

    Replumaz, Anne; Funiciello, Francesca; Reitano, Riccardo; Faccenna, Claudio; Balon, Marie

    2016-04-01

    The mechanisms involved in the creation of the high and wide topography, like the Tibetan Plateau, are still controversial. In particular, the behaviour of the indian and asian lower continental lithosphere during the collision is a matter of debate, either thickening, densifying and delaminating, or keeping its rigidity and subducting. But since several decades seismicity, seismic profiles and global tomography highlight the lithospheric structure of the Tibetan Plateau, and make the hypotheses sustaining the models more precise. In particular, in the western syntaxis, it is now clear that the indian lithosphere subducts northward beneath the Hindu Kush down to the transition zone, while the asian one subducts southward beneath Pamir (e.g. Negredo et al., 2007; Kufner et al., 2015). Such double subduction of continental lithospheres with opposite vergence has also been inferred in the early collision time. Cenozoic volcanic rocks between 50 and 30 Ma in the Qiangtang block have been interpreted as related to an asian subduction beneath Qiangtang at that time (De Celles et al., 2011; Guillot and Replumaz, 2013). We present here analogue experiments silicone/honey to explore the subduction of continental lithosphere, using a piston as analogue of far field forces. We explore the parameters that control the subductions dynamics of the 2 continental lithospheres and the thickening of the plates at the surface, and compare with the Tibetan Plateau evolution. We show that a continental lithosphere is able to subduct in a collision context, even lighter than the mantle, if the plate is rigid enough. In that case the horizontal force due to the collision context, modelled by the piston push transmitted by the indenter, is the driving force, not the slab pull which is negative. It is not a subduction driving by the weight of the slab, but a subduction induced by the collision, that we could call "collisional subduction".

  19. Continental tectonics in the aftermath of plate tectonics

    NASA Technical Reports Server (NTRS)

    Molnar, Peter

    1988-01-01

    It is shown that the basic tenet of plate tectonics, rigid-body movements of large plates of lithosphere, fails to apply to continental interiors. There, buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is discussed. Future areas of investigation are addressed.

  20. H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones

    NASA Astrophysics Data System (ADS)

    Labrousse, L.; Duretz, T.; Gerya, T.

    2015-10-01

    We present two-dimensional numerical models of plate subduction and collision inspired by the Scandinavian Caledonian orogeny to investigate the possible impact of continental crust partial melting on the exhumation of ultra-high pressure metamorphic rocks. Three possible reactions were tested: low temperature solidus representing H2O-fluid-saturated partial melting, and two end-member reaction curves for dehydration melting. Thermo-mechanical effects of partial melting were implemented as (1) a viscosity decrease as a determined rheologically critical melt percentage was reached (here 0.1), (2) a change in effective heat capacity and adiabatic heating/cooling accounting for a latent heat term in the heat equation. Among the 3 tested reactions, only H2O-fluid-saturated partial melting drastically modifies the collision dynamics from the non-melting reference model holding all other parameters constant. A substantially low general viscosity truncation (here 1017 Pa s) is needed to properly resolve the effect of partial melting on deep collision processes. Low temperature melting indeed induces the development of a low viscosity buoyant plume prior to slab detachment, where migmatites exhume from UHP conditions at rates and with pressure-temperature paths similar to the natural values acknowledged for the Norwegian Caledonides. High temperature melting has no drastic influence on early collision dynamics. While positive buoyancy remains the first order driver for the exhumation of buried continental rocks, exhumation initiates in these cases with eduction subsequent to slab detachment. Melting and formation of a migmatite plume can later occur along decompression path while continental crust undergoes thermal reequilibration at temperatures above 900 °C. Some of the partially molten material can also relaminate in the overriding plate rather than exhume within the collision zone. Even if minor in terms of amount of magma produced, H2O-fluid-saturated partial melting

  1. Coordination: Southeast continental shelf studies

    SciTech Connect

    Menzel, D.W.

    1989-01-26

    The objective of this investigation is to obtain model descriptions of the flow modifications in the Southeast Atlantic continental shelf due to Gulf Stream fluctuations and topographic effects. 2 refs., 4 figs.

  2. Numerical Models of Subduction to Collision in Taiwan.

    NASA Astrophysics Data System (ADS)

    Lavier, L. L.; Wu, F. T.; Okaya, D.; McIntosh, K.

    2007-12-01

    The Island of Taiwan is formed by the collision of the Philippine Sea plate with the Eurasian plate. In the south, the Philippine Sea plate overlies a seismically active subduction zone. On the other hand the Central Range is underlain by only crustal seismicity. Does the Asian continent actively subduct into the upper mantle under the Central Range or does it underplate the Luzon arc? Do the resulting large-scale structures provide the dynamic forces to explain the pattern of deformation observed across Taiwan? We study the dynamic evolution of the Taiwanese orogeny using 2D elastic-plastic and viscoelastic numerical models of deformation of the lithosphere. We drive this modeling exercise from the assumption that the present day structure and motion depend on the long-term stress and strain history of the lithosphere. We start the models from the subduction of the Eurasian plate under the Philippine Sea plate and let it evolve to the collision of the Eurasian plate with the Luzon arc. We find that whether or not the Asian crust is dragged in the mantle is dependent on the crustal structure of the South China Sea margin. If the ocean continent transition there is mainly formed of thinned continental crust the accumulated buoyancy of the thickened crust during collision generates forces large enough to tear the subducting slab off the margin. If it consists of accreted oceanic crust the margin is dragged into the upper mantle and the slab stays attached to the Asian plate. Both scenarios lead to predictions on the type of structures and motions that should be observed by future seismic experiments in Taiwan.

  3. Numerical Models of Subduction to Collision in Taiwan.

    NASA Astrophysics Data System (ADS)

    Lavier, L. L.; Wu, F. T.; Okaya, D.; McIntosh, K.

    2004-12-01

    The Island of Taiwan is formed by the collision of the Philippine Sea plate with the Eurasian plate. In the south, the Philippine Sea plate overlies a seismically active subduction zone. On the other hand the Central Range is underlain by only crustal seismicity. Does the Asian continent actively subduct into the upper mantle under the Central Range or does it underplate the Luzon arc? Do the resulting large-scale structures provide the dynamic forces to explain the pattern of deformation observed across Taiwan? We study the dynamic evolution of the Taiwanese orogeny using 2D elastic-plastic and viscoelastic numerical models of deformation of the lithosphere. We drive this modeling exercise from the assumption that the present day structure and motion depend on the long-term stress and strain history of the lithosphere. We start the models from the subduction of the Eurasian plate under the Philippine Sea plate and let it evolve to the collision of the Eurasian plate with the Luzon arc. We find that whether or not the Asian crust is dragged in the mantle is dependent on the crustal structure of the South China Sea margin. If the ocean continent transition there is mainly formed of thinned continental crust the accumulated buoyancy of the thickened crust during collision generates forces large enough to tear the subducting slab off the margin. If it consists of accreted oceanic crust the margin is dragged into the upper mantle and the slab stays attached to the Asian plate. Both scenarios lead to predictions on the type of structures and motions that should be observed by future seismic experiments in Taiwan.

  4. -induced continental warming

    NASA Astrophysics Data System (ADS)

    Kamae, Youichi; Watanabe, Masahiro; Kimoto, Masahide; Shiogama, Hideo

    2014-11-01

    In this the second of a two-part study, we examine the physical mechanisms responsible for the increasing contrast of the land-sea surface air temperature (SAT) in summertime over the Far East, as observed in recent decades and revealed in future climate projections obtained from a series of transient warming and sensitivity experiments conducted under the umbrella of the Coupled Model Intercomparison Project phase 5. On a global perspective, a strengthening of land-sea SAT contrast in the transient warming simulations of coupled atmosphere-ocean general circulation models is attributed to an increase in sea surface temperature (SST). However, in boreal summer, the strengthened contrast over the Far East is reproduced only by increasing atmospheric CO2 concentration. In response to SST increase alone, the tropospheric warming over the interior of the mid- to high-latitude continents including Eurasia are weaker than those over the surrounding oceans, leading to a weakening of the land-sea SAT contrast over the Far East. Thus, the increasing contrast and associated change in atmospheric circulation over East Asia is explained by CO2-induced continental warming. The degree of strengthening of the land-sea SAT contrast varies in different transient warming scenarios, but is reproduced through a combination of the CO2-induced positive and SST-induced negative contributions to the land-sea contrast. These results imply that changes of climate patterns over the land-ocean boundary regions are sensitive to future scenarios of CO2 concentration pathways including extreme cases.

  5. Investigation of Biomass Combustion Rate of Fire Radiative Energy Using Multiple-Satellite-observed Active Fires and Landsat TM Burn Severities across the Continental United States

    NASA Astrophysics Data System (ADS)

    Li, F.; Zhang, X.; Kondragunta, S.

    2015-12-01

    Biomass burning is a major source of atmospheric aerosol and greenhouse gases that substantially influence climate and regional air quality. However, the accuracy of biomass burning emissions estimated using traditional method is limited by large uncertainties in burned area and fuel loading. Alternatively, fire radiative energy (FRE) has recently been demonstrated to be linearly related to biomass combustion, which potentially improves the estimation of biomass burning emissions. The FRE-based combustion rate is 0.368-0.453 kg/MJ according to field controlled experiments while it varies from 1.37-4.5 kg/MJ derived from satellite-based bottom-up and top-down aerosol optical thickness estimates. Here we investigate the FRE combustion rate in over 1000 burn scars from 2011 to 2012 across the Continental United States (CONUS). Specifically, FRE was calculated by combining the high spatial observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the high temporal observations from the Geostationary Operational Environmental Satellite (GOES). Biomass consumption in burn scars was modeled using Landsat TM 30m burn severities, 30m fuel loading from Fuel Characteristic Classification System, and combustion completeness compiled from recent literatures. The combustion rate was then investigated by correlating FRE to biomass consumption across CONUS and Bailey's ecoregions. Our results show that the combustion rate can be extracted from the linear relationship between biomass consumption and FRE. The combustion rate is 0.415±10% kg/MJ across CONUS, which is similar to the rate derived from field experiments. However, it varies from 0.18-1.9 kg/MJ among ecoregions. This implies that a single combustion rate could produce large uncertainty in the estimation of biomass consumption at large scales. We suggest that ecoregion specified combustion rates should help to improve the accuracy of quantifying biomass burning emissions regionally and globally.

  6. Seismotectonics of the southern boundary of Anatolia, Eastern Mediterranean region: subduction, collision, and arc jumping

    SciTech Connect

    Rotstein, Y.; Kafka, A.L.

    1982-09-10

    The pattern of seismicity and fault plane solutions of earthquakes are used to outline the tectonic features of the southern boundary of Anatolia in the eastern Mediterranean and southeastern Turkey. The results of this study show that this boundary is composed of two distinct parts. One, in southeastern Turkey and Syria, is a wide and complex zone of continental collision. The other, in the Levantine basin of the eastern Mediterranean, is a zone of oceanic subduction. In the region of continental collision three zones of seismicity are observed. Most of the seismic activity in this region follows the Bitlis zone and is associated with a zone of thrusting and mountain building. This appears to be the zone of most active deformation and plate consumption in the plate boundary region between Arabia and Turkey. A less active zone of seismicity to the north of the Bitlis zone is interpreted to have been more active in the past whereas another active zone of seismicity to the south is interpreted to be a zone which may be more active in the future as the main zone of plate consumption jumps to the south. In the subduction zone of the eastern Mediterranean the depth of the subducted slab and the rate of seismicity generally increease from east to west. The zone of present-day convergence between Africa and Turkey in the Levantine basin can be best outlined by the northern edge of the Mediterranean ridge. Deep seismic activity near the Gulf of Antalya is associated with a detached subducted slab north of the Anaximander Mountains that is distinctly different from the seismic trend which is associated with present-day active subduction. Most of the focal mechanisms of the earthquakes along the entire southern boundary of Anatolia indicate that N to NNW thrusting is the dominant mode of seismic deformation.

  7. Puck collisions

    NASA Astrophysics Data System (ADS)

    Hauge, E. H.

    2012-09-01

    Collisions between two ice hockey pucks sliding on frictionless ice are studied, with both inelasticity and frictional contact between the colliding surfaces of the two pucks taken into account. The latter couples translational and rotational motion. The full solution depends on the sign and magnitude of the initial mismatch between the surface velocities at the point of contact. The initial state defines two physically distinct regimes for the friction coefficient. To illustrate the complexities, we discuss at length the typical situation (well known from curling) when puck number 1 is initially at rest, and is hit by puck number 2 with an arbitrary impact parameter, velocity and angular velocity. We find that the total outgoing angle between the pucks exceeds \\frac{1}{2}\\pi if and only if the collision leads to a net increase in the translational part of the kinetic energy. The conditions for this to happen are scrutinized, and the results are presented both analytically and numerically by a set of representative curves. This paper is written with an ambitious undergraduate, and her teacher, in mind.

  8. Oceanic microplate formation records the onset of India-Eurasia collision

    NASA Astrophysics Data System (ADS)

    Matthews, Kara J.; Dietmar Müller, R.; Sandwell, David T.

    2016-01-01

    Mapping of seafloor tectonic fabric in the Indian Ocean, using high-resolution satellite-derived vertical gravity gradient data, reveals an extinct Pacific-style oceanic microplate ('Mammerickx Microplate') west of the Ninetyeast Ridge. It is one of the first Pacific-style microplates to be mapped outside the Pacific basin, suggesting that geophysical conditions during formation probably resembled those that have dominated at eastern Pacific ridges. The microplate formed at the Indian-Antarctic ridge and is bordered by an extinct ridge in the north and pseudofault in the south, whose conjugate is located north of the Kerguelen Plateau. Independent microplate rotation is indicated by asymmetric pseudofaults and rotated abyssal hill fabric, also seen in multibeam data. Magnetic anomaly picks and age estimates calculated from published spreading rates suggest formation during chron 21o (∼47.3 Ma). Plate reorganizations can trigger ridge propagation and microplate development, and we propose that Mammerickx Microplate formation is linked with the India-Eurasia collision (initial 'soft' collision). The collision altered the stress regime at the Indian-Antarctic ridge, leading to a change in segmentation and ridge propagation from an establishing transform. Fast Indian-Antarctic spreading that preceded microplate formation, and Kerguelen Plume activity, may have facilitated ridge propagation via the production of thin and weak lithosphere; however both factors had been present for tens of millions of years and are therefore unlikely to have triggered the event. Prior to the collision, the combination of fast spreading and plume activity was responsible for the production of a wide region of undulate seafloor to the north of the extinct ridge and 'W' shaped lineations that record back and forth ridge propagation. Microplate formation provides a precise means of dating the onset of the India-Eurasia collision, and is completely independent of and complementary to timing

  9. A mid-crustal strain-transfer model for continental deformation: A new perspective from high-resolution deep seismic-reflection profiling across NE Tibet

    NASA Astrophysics Data System (ADS)

    Wang, Chengshan; Gao, Rui; Yin, An; Wang, Haiyan; Zhang, Yuxiu; Guo, Tonglou; Li, Qusheng; Li, Yalin

    2011-06-01

    Understanding why continental deformation departs from the theory of plate tectonics requires a detailed knowledge of three-dimensional structures at a lithospheric scale. In Tibet, the end-member models of continental deformation make distinctively different predictions on strain distribution and contrasting structural geometry as a function of depth. Specifically, the thin-viscous-sheet model predicts vertically coherent deformation while channel-flow and continental-subduction models predict the presence of sub-horizontal detachment zones within or at the base of the Tibetan crust during the Cenozoic deformation. To differentiate the above models, we conducted a high-resolution seismic-reflection survey across the active left-slip Kunlun fault and its nearby contractional structures. The results of this work show that the actively deforming middle Tibetan crust is dominated by discrete sub-horizontal simple-shear zones that terminate the sub-vertical, left-slip Kunlun fault above and mantle-cutting thrusts below. The flat shear zones appear to act as roof and floor thrusts of large duplex structures that transfer shortening strain from locally deformed and coupled lower crust and mantle lithosphere below to the high-strain domains of the upper crust above. The middle-crustal strain-transfer model proposed here implies that the weak Tibetan middle crust may not be active everywhere during the Indo-Asian collision. It also predicts that the kinematics of the activated portions of the middle crust, whether being deformed by simple shear or channel-flow deformation, may vary from place to place, depending strongly on the lateral variation of mechanical strength at different depths of the lithosphere. Our approach of establishing the kinematics of middle-crust deformation departs significantly from the early work that emphasizes exclusively the role of vertically varying rheology in controlling the mode of continental deformation.

  10. Event activity dependence of (nS) production in = 5 .02 TeV pPb and = 2 .76 TeV pp collisions

    NASA Astrophysics Data System (ADS)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Krätschmer, I.; Liko, D.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Gonzalez, J. Suarez; Alderweireldt, S.; Bansal, M.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Luyckx, S.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Heracleous, N.; Kalogeropoulos, A.; Keaveney, J.; Kim, T. J.; Lowette, S.; Maes, M.; Olbrechts, A.; Strom, D.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. 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J.; Bergholz, M.; Bethani, A.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Choudhury, S.; Costanza, F.; Diez Pardos, C.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Geiser, A.; Grebenyuk, A.; Gunnellini, P.; Habib, S.; Hauk, J.; Hellwig, G.; Hempel, M.; Horton, D.; Jung, H.; Kasemann, M.; Katsas, P.; Kleinwort, C.; Kluge, H.; Krämer, M.; Krücker, D.; Lange, W.; Leonard, J.; Lipka, K.; Lohmann, W.; Lutz, B.; Mankel, R.; Marfin, I.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Novgorodova, O.; Nowak, F.; Olzem, J.; Perrey, H.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Ribeiro Cipriano, P. M.; Riedl, C.; Ron, E.; Sahin, M. Ö.; Salfeld-Nebgen, J.; Schmidt, R.; Schoerner-Sadenius, T.; Schröder, M.; Sen, N.; Stein, M.; Vargas Trevino, A. D. R.; Walsh, R.; Wissing, C.; Aldaya Martin, M.; Blobel, V.; Enderle, H.; Erfle, J.; Garutti, E.; Görner, M.; Gosselink, M.; Haller, J.; Heine, K.; Höing, R. S.; Kirschenmann, H.; Klanner, R.; Kogler, R.; Lange, J.; Marchesini, I.; Ott, J.; Peiffer, T.; Pietsch, N.; Rathjens, D.; Sander, C.; Schettler, H.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Schum, T.; Seidel, M.; Sibille, J.; Sola, V.; Stadie, H.; Steinbrück, G.; Troendle, D.; Usai, E.; Vanelderen, L.; Barth, C.; Baus, C.; Berger, J.; Böser, C.; Butz, E.; Chwalek, T.; De Boer, W.; Descroix, A.; Dierlamm, A.; Feindt, M.; Guthoff, M.; Hartmann, F.; Hauth, T.; Held, H.; Hoffmann, K. H.; Husemann, U.; Katkov, I.; Kornmayer, A.; Kuznetsova, E.; Lobelle Pardo, P.; Martschei, D.; Mozer, M. U.; Müller, Th.; Niegel, M.; Nürnberg, A.; Oberst, O.; Quast, G.; Rabbertz, K.; Ratnikov, F.; Röcker, S.; Schilling, F.-P.; Schott, G.; Simonis, H. J.; Stober, F. M.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weiler, T.; Wolf, R.; Zeise, M.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Kesisoglou, S.; Kyriakis, A.; Loukas, D.; Markou, A.; Markou, C.; Ntomari, E.; Topsis-giotis, I.; Gouskos, L.; Panagiotou, A.; Saoulidou, N.; Stiliaris, E.; Aslanoglou, X.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Bencze, G.; Hajdu, C.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Molnar, J.; Palinkas, J.; Szillasi, Z.; Karancsi, J.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Swain, S. K.; Beri, S. B.; Bhatnagar, V.; Dhingra, N.; Gupta, R.; Kaur, M.; Mehta, M. Z.; Mittal, M.; Nishu, N.; Sharma, A.; Singh, J. B.; Kumar, Ashok; Kumar, Arun; Ahuja, S.; Bhardwaj, A.; Choudhary, B. C.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Saxena, P.; Sharma, V.; Shivpuri, R. K.; Banerjee, S.; Bhattacharya, S.; Chatterjee, K.; Dutta, S.; Gomber, B.; Jain, Sa.; Jain, Sh.; Khurana, R.; Modak, A.; Mukherjee, S.; Roy, D.; Sarkar, S.; Sharan, M.; Singh, A. P.; Abdulsalam, A.; Dutta, D.; Kailas, S.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Chatterjee, R. M.; Ganguly, S.; Ghosh, S.; Guchait, M.; Gurtu, A.; Kole, G.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Mohanty, G. B.; Parida, B.; Sudhakar, K.; Wickramage, N.; Banerjee, S.; Dugad, S.; Arfaei, H.; Bakhshiansohi, H.; Behnamian, H.; Etesami, S. M.; Fahim, A.; Jafari, A.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Mehdiabadi, S. Paktinat; Safarzadeh, B.; Zeinali, M.; Grunewald, M.; Abbrescia, M.; Barbone, L.; Calabria, C.; Chhibra, S. S.; Colaleo, A.; Creanza, D.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Marangelli, B.; My, S.; Nuzzo, S.; Pacifico, N.; Pompili, A.; Pugliese, G.; Radogna, R.; Selvaggi, G.; Silvestris, L.; Singh, G.; Venditti, R.; Verwilligen, P.; Zito, G.; Abbiendi, G.; Benvenuti, A. C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Meneghelli, M.; Montanari, A.; Navarria, F. L.; Odorici, F.; Perrotta, A.; Primavera, F.; Rossi, A. M.; Rovelli, T.; Siroli, G. 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V.; Vinogradov, A.; Belyaev, A.; Boos, E.; Ershov, A.; Gribushin, A.; Klyukhin, V.; Kodolova, O.; Korotkikh, V.; Lokhtin, I.; Markina, A.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Vardanyan, I.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Djordjevic, M.; Ekmedzic, M.; Milosevic, J.; Aguilar-Benitez, M.; Maestre, J. Alcaraz; Battilana, C.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Domínguez Vázquez, D.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Ferrando, A.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Merino, G.; Navarro De Martino, E.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Willmott, C.; Albajar, C.; de Trocóniz, J. F.; Brun, H.; Cuevas, J.; Fernandez Menendez, J.; Folgueras, S.; Gonzalez Caballero, I.; Lloret Iglesias, L.; Brochero Cifuentes, J. A.; Cabrillo, I. J.; Calderon, A.; Chuang, S. H.; Duarte Campderros, J.; Fernandez, M.; Gomez, G.; Gonzalez Sanchez, J.; Graziano, A.; Lopez Virto, A.; Marco, J.; Marco, R.; Martinez Rivero, C.; Matorras, F.; Munoz Sanchez, F. J.; Piedra Gomez, J.; Rodrigo, T.; Rodríguez-Marrero, A. Y.; Ruiz-Jimeno, A.; Scodellaro, L.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Auffray, E.; Auzinger, G.; Bachtis, M.; Baillon, P.; Ball, A. H.; Barney, D.; Bendavid, J.; Benhabib, L.; Benitez, J. F.; Bernet, C.; Bianchi, G.; Bloch, P.; Bocci, A.; Bonato, A.; Bondu, O.; Botta, C.; Breuker, H.; Camporesi, T.; Cerminara, G.; Christiansen, T.; Coarasa Perez, J. A.; Colafranceschi, S.; D'Alfonso, M.; d'Enterria, D.; Dabrowski, A.; David, A.; De Guio, F.; De Roeck, A.; De Visscher, S.; Di Guida, S.; Dobson, M.; Dupont-Sagorin, N.; Elliott-Peisert, A.; Eugster, J.; Franzoni, G.; Funk, W.; Giffels, M.; Gigi, D.; Gill, K.; Girone, M.; Giunta, M.; Glege, F.; Gomez-Reino Garrido, R.; Gowdy, S.; Guida, R.; Hammer, J.; Hansen, M.; Harris, P.; Hinzmann, A.; Innocente, V.; Janot, P.; Karavakis, E.; Kousouris, K.; Krajczar, K.; Lecoq, P.; Lee, Y.-J.; Lourenço, C.; Magini, N.; Malgeri, L.; Mannelli, M.; Masetti, L.; Meijers, F.; Mersi, S.; Meschi, E.; Moortgat, F.; Mulders, M.; Musella, P.; Orsini, L.; Palencia Cortezon, E.; Perez, E.; Perrozzi, L.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Pimiä, M.; Piparo, D.; Plagge, M.; Racz, A.; Reece, W.; Rolandi, G.; Rovere, M.; Sakulin, H.; Santanastasio, F.; Schäfer, C.; Schwick, C.; Sekmen, S.; Sharma, A.; Siegrist, P.; Silva, P.; Simon, M.; Sphicas, P.; Steggemann, J.; Stieger, B.; Stoye, M.; Tsirou, A.; Veres, G. I.; Vlimant, J. R.; Wöhri, H. K.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Gabathuler, K.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; König, S.; Kotlinski, D.; Langenegger, U.; Renker, D.; Rohe, T.; Bachmair, F.; Bäni, L.; Bianchini, L.; Bortignon, P.; Buchmann, M. A.; Casal, B.; Chanon, N.; Deisher, A.; Dissertori, G.; Dittmar, M.; Donegà, M.; Dünser, M.; Eller, P.; Grab, C.; Hits, D.; Lustermann, W.; Mangano, B.; Marini, A. C.; Martinez Ruiz del Arbol, P.; Meister, D.; Mohr, N.; Nägeli, C.; Nef, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pape, L.; Pauss, F.; Peruzzi, M.; Quittnat, M.; Ronga, F. J.; Rossini, M.; Sala, L.; Starodumov, A.; Takahashi, M.; Tauscher, L.; Theofilatos, K.; Treille, D.; Wallny, R.; Weber, H. A.; Amsler, C.; Chiochia, V.; De Cosa, A.; Favaro, C.; Ivova Rikova, M.; Kilminster, B.; Millan Mejias, B.; Ngadiuba, J.; Robmann, P.; Snoek, H.; Taroni, S.; Verzetti, M.; Yang, Y.; Cardaci, M.; Chen, K. H.; Ferro, C.; Kuo, C. M.; Li, S. W.; Lin, W.; Lu, Y. J.; Volpe, R.; Yu, S. S.; Bartalini, P.; Chang, P.; Chang, Y. H.; Chang, Y. W.; Chao, Y.; Chen, K. F.; Dietz, C.; Grundler, U.; Hou, W.-S.; Hsiung, Y.; Kao, K. Y.; Lei, Y. J.; Liu, Y. F.; Lu, R.-S.; Majumder, D.; Petrakou, E.; Shi, X.; Shiu, J. G.; Tzeng, Y. M.; Wang, M.; Wilken, R.; Asavapibhop, B.; Suwonjandee, N.; Adiguzel, A.; Bakirci, M. N.; Cerci, S.; Dozen, C.; Dumanoglu, I.; Eskut, E.; Girgis, S.; Gokbulut, G.; Gurpinar, E.; Hos, I.; Kangal, E. E.; Kayis Topaksu, A.; Onengut, G.; Ozdemir, K.; Ozturk, S.; Polatoz, A.; Sogut, K.; Sunar Cerci, D.; Tali, B.; Topakli, H.; Vergili, M.; Akin, I. V.; Aliev, T.; Bilin, B.; Bilmis, S.; Deniz, M.; Gamsizkan, H.; Guler, A. M.; Karapinar, G.; Ocalan, K.; Ozpineci, A.; Serin, M.; Sever, R.; Surat, U. E.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Isildak, B.; Kaya, M.; Kaya, O.; Ozkorucuklu, S.; Sonmez, N.; Bahtiyar, H.; Barlas, E.; Cankocak, K.; Günaydin, Y. O.; Vardarlı, F. I.; Yücel, M.; Levchuk, L.; Sorokin, P.; Brooke, J. J.; Clement, E.; Cussans, D.; Flacher, H.; Frazier, R.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Jacob, J.; Kreczko, L.; Lucas, C.; Meng, Z.; Metson, S.; Newbold, D. M.; Nirunpong, K.; Paramesvaran, S.; Poll, A.; Senkin, S.; Smith, V. J.; Williams, T.; Belyaev, A.; Brew, C.; Brown, R. M.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Ilic, J.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Womersley, W. J.; Worm, S. D.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Burton, D.; Colling, D.; Cripps, N.; Cutajar, M.; Dauncey, P.; Davies, G.; Della Negra, M.; Ferguson, W.; Fulcher, J.; Futyan, D.; Gilbert, A.; Guneratne Bryer, A.; Hall, G.; Hatherell, Z.; Hays, J.; Iles, G.; Jarvis, M.; Karapostoli, G.; Kenzie, M.; Lane, R.; Lucas, R.; Lyons, L.; Magnan, A.-M.; Marrouche, J.; Mathias, B.; Nandi, R.; Nash, J.; Nikitenko, A.; Pela, J.; Pesaresi, M.; Petridis, K.; Pioppi, M.; Raymond, D. M.; Rogerson, S.; Rose, A.; Seez, C.; Sharp, P.; Sparrow, A.; Tapper, A.; Acosta, M. Vazquez; Virdee, T.; Wakefield, S.; Wardle, N.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leggat, D.; Leslie, D.; Martin, W.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Dittmann, J.; Hatakeyama, K.; Kasmi, A.; Liu, H.; Scarborough, T.; Charaf, O.; Cooper, S. I.; Henderson, C.; Rumerio, P.; Avetisyan, A.; Bose, T.; Fantasia, C.; Heister, A.; Lawson, P.; Lazic, D.; Rohlf, J.; Sperka, D.; St. John, J.; Sulak, L.; Alimena, J.; Bhattacharya, S.; Christopher, G.; Cutts, D.; Demiragli, Z.; Ferapontov, A.; Garabedian, A.; Heintz, U.; Jabeen, S.; Kukartsev, G.; Laird, E.; Landsberg, G.; Luk, M.; Narain, M.; Segala, M.; Sinthuprasith, T.; Speer, T.; Breedon, R.; Breto, G.; Calderon De La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Gardner, M.; Ko, W.; Kopecky, A.; Lander, R.; Miceli, T.; Pellett, D.; Pilot, J.; Ricci-Tam, F.; Rutherford, B.; Searle, M.; Shalhout, S.; Smith, J.; Squires, M.; Tripathi, M.; Wilbur, S.; Yohay, R.; Andreev, V.; Cline, D.; Cousins, R.; Erhan, S.; Everaerts, P.; Farrell, C.; Felcini, M.; Hauser, J.; Ignatenko, M.; Jarvis, C.; Rakness, G.; Schlein, P.; Takasugi, E.; Valuev, V.; Weber, M.; Babb, J.; Clare, R.; Ellison, J.; Gary, J. W.; Hanson, G.; Heilman, J.; Jandir, P.; Lacroix, F.; Liu, H.; Long, O. R.; Luthra, A.; Malberti, M.; Nguyen, H.; Shrinivas, A.; Sturdy, J.; Sumowidagdo, S.; Wimpenny, S.; Andrews, W.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; D'Agnolo, R. T.; Evans, D.; Holzner, A.; Kelley, R.; Kovalskyi, D.; Lebourgeois, M.; Letts, J.; Macneill, I.; Padhi, S.; Palmer, C.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Sudano, E.; Tadel, M.; Tu, Y.; Vartak, A.; Wasserbaech, S.; Würthwein, F.; Yagil, A.; Yoo, J.; Barge, D.; Campagnari, C.; Danielson, T.; Flowers, K.; Geffert, P.; George, C.; Golf, F.; Incandela, J.; Justus, C.; Magaña Villalba, R.; Mccoll, N.; Pavlunin, V.; Richman, J.; Rossin, R.; Stuart, D.; To, W.; West, C.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Di Marco, E.; Duarte, J.; Kcira, D.; Ma, Y.; Mott, A.; Newman, H. B.; Pena, C.; Rogan, C.; Spiropulu, M.; Timciuc, V.; Wilkinson, R.; Xie, S.; Zhu, R. Y.; Azzolini, V.; Calamba, A.; Carroll, R.; Ferguson, T.; Iiyama, Y.; Jang, D. W.; Paulini, M.; Russ, J.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Drell, B. R.; Ford, W. T.; Gaz, A.; Lopez, E. Luiggi; Nauenberg, U.; Smith, J. G.; Stenson, K.; Ulmer, K. A.; Wagner, S. R.; Alexander, J.; Chatterjee, A.; Eggert, N.; Gibbons, L. K.; Hopkins, W.; Khukhunaishvili, A.; Kreis, B.; Mirman, N.; Kaufman, G. Nicolas; Patterson, J. R.; Ryd, A.; Salvati, E.; Sun, W.; Teo, W. D.; Thom, J.; Thompson, J.; Tucker, J.; Weng, Y.; Winstrom, L.; Wittich, P.; Winn, D.; Abdullin, S.; Albrow, M.; Anderson, J.; Apollinari, G.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Burkett, K.; Butler, J. N.; Chetluru, V.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gao, Y.; Gottschalk, E.; Gray, L.; Green, D.; Gutsche, O.; Hare, D.; Harris, R. M.; Hirschauer, J.; Hooberman, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Kaadze, K.; Klima, B.; Kwan, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Outschoorn, V. I. Martinez; Maruyama, S.; Mason, D.; McBride, P.; Mishra, K.; Mrenna, S.; Musienko, Y.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Prokofyev, O.; Ratnikova, N.; Sexton-Kennedy, E.; Sharma, S.; Spalding, W. J.; Spiegel, L.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vidal, R.; Whitmore, J.; Wu, W.; Yang, F.; Yun, J. C.; Acosta, D.; Avery, P.; Bourilkov, D.; Cheng, T.; Das, S.; De Gruttola, M.; Di Giovanni, G. P.; Dobur, D.; Field, R. D.; Fisher, M.; Fu, Y.; Furic, I. K.; Hugon, J.; Kim, B.; Konigsberg, J.; Korytov, A.; Kropivnitskaya, A.; Kypreos, T.; Low, J. F.; Matchev, K.; Milenovic, P.; Mitselmakher, G.; Muniz, L.; Rinkevicius, A.; Skhirtladze, N.; Snowball, M.; Yelton, J.; Zakaria, M.; Gaultney, V.; Hewamanage, S.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Adams, T.; Askew, A.; Bochenek, J.; Chen, J.; Diamond, B.; Haas, J.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Prosper, H.; Veeraraghavan, V.; Weinberg, M.; Baarmand, M. M.; Dorney, B.; Hohlmann, M.; Kalakhety, H.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Bazterra, V. E.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Khalatyan, S.; Kurt, P.; Moon, D. H.; O'Brien, C.; Silkworth, C.; Turner, P.; Varelas, N.; Akgun, U.; Albayrak, E. A.; Bilki, B.; Clarida, W.; Dilsiz, K.; Duru, F.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Sen, S.; Tan, P.; Tiras, E.; Wetzel, J.; Yetkin, T.; Yi, K.; Barnett, B. A.; Blumenfeld, B.; Bolognesi, S.; Fehling, D.; Gritsan, A. V.; Maksimovic, P.; Martin, C.; Swartz, M.; Whitbeck, A.; Baringer, P.; Bean, A.; Benelli, G.; Kenny, R. P.; Murray, M.; Noonan, D.; Sanders, S.; Sekaric, J.; Stringer, R.; Wang, Q.; Wood, J. S.; Barfuss, A. F.; Chakaberia, I.; Ivanov, A.; Khalil, S.; Makouski, M.; Maravin, Y.; Saini, L. K.; Shrestha, S.; Svintradze, I.; Gronberg, J.; Lange, D.; Rebassoo, F.; Wright, D.; Baden, A.; Calvert, B.; Eno, S. C.; Gomez, J. A.; Hadley, N. J.; Kellogg, R. G.; Kolberg, T.; Lu, Y.; Marionneau, M.; Mignerey, A. C.; Pedro, K.; Skuja, A.; Temple, J.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Bauer, G.; Busza, W.; Cali, I. A.; Chan, M.; Di Matteo, L.; Dutta, V.; Ceballos, G. Gomez; Goncharov, M.; Gulhan, D.; Klute, M.; Lai, Y. S.; Levin, A.; Luckey, P. D.; Ma, T.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Stephans, G. S. F.; Stöckli, F.; Sumorok, K.; Velicanu, D.; Veverka, J.; Wyslouch, B.; Yang, M.; Yoon, A. S.; Zanetti, M.; Zhukova, V.; Dahmes, B.; De Benedetti, A.; Gude, A.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Mans, J.; Pastika, N.; Rusack, R.; Singovsky, A.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Cremaldi, L. M.; Kroeger, R.; Oliveros, S.; Perera, L.; Rahmat, R.; Sanders, D. A.; Summers, D.; Avdeeva, E.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Suarez, R. Gonzalez; Keller, J.; Kravchenko, I.; Lazo-Flores, J.; Malik, S.; Meier, F.; Snow, G. R.; Dolen, J.; Godshalk, A.; Iashvili, I.; Jain, S.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Wan, Z.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Haley, J.; Massironi, A.; Nash, D.; Orimoto, T.; Trocino, D.; Wood, D.; Zhang, J.; Anastassov, A.; Hahn, K. A.; Kubik, A.; Lusito, L.; Mucia, N.; Odell, N.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Sung, K.; Velasco, M.; Won, S.; Berry, D.; Brinkerhoff, A.; Chan, K. M.; Drozdetskiy, A.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kolb, J.; Lannon, K.; Luo, W.; Lynch, S.; Marinelli, N.; Morse, D. M.; Pearson, T.; Planer, M.; Ruchti, R.; Slaunwhite, J.; Valls, N.; Wayne, M.; Wolf, M.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Hill, C.; Hughes, R.; Kotov, K.; Ling, T. Y.; Puigh, D.; Rodenburg, M.; Smith, G.; Vuosalo, C.; Winer, B. L.; Wolfe, H.; Wulsin, H. W.; Berry, E.; Elmer, P.; Halyo, V.; Hebda, P.; Hegeman, J.; Hunt, A.; Jindal, P.; Koay, S. A.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Piroué, P.; Quan, X.; Raval, A.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zenz, S. C.; Zuranski, A.; Brownson, E.; Lopez, A.; Mendez, H.; Ramirez Vargas, J. E.; Alagoz, E.; Benedetti, D.; Bolla, G.; Bortoletto, D.; De Mattia, M.; Everett, A.; Hu, Z.; Jones, M.; Jung, K.; Kress, M.; Leonardo, N.; Lopes Pegna, D.; Maroussov, V.; Merkel, P.; Miller, D. H.; Neumeister, N.; Radburn-Smith, B. C.; Shipsey, I.; Silvers, D.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Yoo, H. D.; Zablocki, J.; Zheng, Y.; Parashar, N.; Adair, A.; Akgun, B.; Ecklund, K. M.; Geurts, F. J. M.; Li, W.; Michlin, B.; Padley, B. P.; Redjimi, R.; Roberts, J.; Zabel, J.; Betchart, B.; Bodek, A.; Covarelli, R.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Garcia-Bellido, A.; Goldenzweig, P.; Han, J.; Harel, A.; Miner, D. C.; Petrillo, G.; Vishnevskiy, D.; Zielinski, M.; Bhatti, A.; Ciesielski, R.; Demortier, L.; Goulianos, K.; Lungu, G.; Malik, S.; Mesropian, C.; Arora, S.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Lath, A.; Panwalkar, S.; Park, M.; Patel, R.; Rekovic, V.; Robles, J.; Salur, S.; Schnetzer, S.; Seitz, C.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Rose, K.; Spanier, S.; Yang, Z. C.; York, A.; Bouhali, O.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Khotilovich, V.; Krutelyov, V.; Montalvo, R.; Osipenkov, I.; Pakhotin, Y.; Perloff, A.; Roe, J.; Safonov, A.; Sakuma, T.; Suarez, I.; Tatarinov, A.; Toback, D.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Kovitanggoon, K.; Kunori, S.; Lee, S. W.; Libeiro, T.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Sharma, M.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Arenton, M. W.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Lin, C.; Neu, C.; Wood, J.; Gollapinni, S.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Sakharov, A.; Belknap, D. A.; Borrello, L.; Carlsmith, D.; Cepeda, M.; Dasu, S.; Duric, S.; Friis, E.; Grothe, M.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Klukas, J.; Lanaro, A.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ross, I.; Sarangi, T.; Savin, A.; Smith, W. H.; Swanson, J.

    2014-04-01

    The production of (1S), (2S), and (3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 nb-1 (pPb) and 5.4 pb-1 (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval | y CM| < 1 .93 in the nucleon-nucleon centre-of-mass frame. Their production is studied as a function of two measures of event activity, namely the charged-particle multiplicity measured in the pseudorapidity interval | η| < 2 .4, and the sum of transverse energy deposited at forward pseudorapidity, 4 .0 < | η| < 5 .2. The cross sections normalized by their event activity integrated values, (nS) /<(nS)>, are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, (nS) / (1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. The event activity integrated double ratios, [(nS) / (1S)]pPb /[(nS) / (1S)]pp, are also measured and found to be 0 .83 ± 0 .05 (stat .) ± 0 .05 (syst .) and 0 .71 ± 0 .08 (stat .) ± 0 .09 (syst .) for (2S) and (3S), respectively. [Figure not available: see fulltext.

  11. Deforming Balkans : Insights on Continental Collisional Processes from GPS Data.

    NASA Astrophysics Data System (ADS)

    Metois, M.; D'Agostino, N.; Avallone, A.; Chamot-Rooke, N. R. A.; Rabaute, A.; Duni, L.; Kuka, N.; Koci, R.; Georgiev, I.

    2014-12-01

    The Balkans region that sits at the transition between stable Eurasia and highly straining Eastern Mediterranean, is a natural laboratory to study diffuse deformation of areas affected by continental collision. As in the Himalayan collision zone, it results in a widespread seismicity and underestimated seismic hazard (England & Jackson, 2011). Several Mw~6 shallow earthquakes occurred there in the last century producing large destructions and casualties. The completeness interval of the available historical seismicity catalogs is probably below the average recurrence of individual seismogenic structures, making them insufficient for accurate estimates of seismic hazard there. However, cGPS networks in the Balkans have been growing during the last few years mainly for civilian application, opening new opportunities to quantify the present-day rates of crustal deformation. Here, we processed all the currently available data acquired on these new networks using the Gipsy-Oasis software and combined them with previously published velocities. We use this dense velocity field together with tensor moments from RCMT and CMT to derive an homogeneous map of the current-day strain using the methodology of Haines & Holt (1993). We image the deformation resulting from the boundary conditions around the Balkans : (i) the NE motion of Adria-Apulia blocks, (ii) the rigid Eurasian and Black sea backstops, (iii) the hellenic subduction zone and NAF rapid SE motion. We show that the «Adria-Apulia push» is nearly entirely accommodated by compression across the Dinarides with minor propagation in the Pannonian basin. On the other hand, East of 20°E, the entire peninsula is moving southward, probably driven by the hellenic subduction pull. The transition between the SW-NE compressive and the N-S extensive regimes roughly corresponds to the Scutari-Pec transform zone, also known to be a boundary between paleomagnetic domains. Therefore, we show that the clockwise rotation pattern

  12. High-energy collision-activated and electron-transfer dissociation of gas-phase complexes of tryptophan with Na+, K+, and Ca2+

    NASA Astrophysics Data System (ADS)

    Fujihara, Akimasa; Sha, Yuki; Matsuo, Sou; Toyoda, Michisato; Hayakawa, Shigeo

    2014-10-01

    The structure and reactivity of gas-phase complexes of tryptophan (Trp) with Na+, K+, and Ca2+ were examined by high-energy collision-activated dissociation (CAD) and electron transfer dissociation (ETD) using alkali metal targets. In the CAD spectra of M+Trp (M = Na and K), neutral Trp loss was the primary dissociation pathway, and the product ion of collision-induced intracomplex electron transfer from the indole π ring of Trp to the alkali metal ion was observed, indicating a charge-solvated structure in which Trp is non-zwitterionic. The NH3 loss observed in the CAD spectrum of Ca2+Trp2 is ascribed to a CZ (mixed charge-solvated/zwitterionic)-type structure, in which one Trp is non-zwitterionic and the other Trp adopts a zwitterionic structure with an NH3+ moiety. The H atom and NH3 losses observed in the ETD spectrum of Ca2+Trp2 indicate the formation of a hypervalent radical in the complex, R-NH3, via electron transfer from the alkali metal target to the NH3+ group of the CZ-type structure. Ca2+ attachment to Trp cluster induces the zwitterionic structure of Trp in the gas phase, and an electron transfer to the zwitterionic Trp forms the hypervalent radical as a reaction intermediate.

  13. Tectonomagmatic Evolution of the Neo - Tethyan Region in the Iranian Continental Margin

    NASA Astrophysics Data System (ADS)

    Monsef, R.; Monsef, I.; Rahgoshay, M.; Emami, M. H.; Shafaii Moghadam, H.

    2009-04-01

    The tectonic history of Neo - Tethyan realm in Iran began with the rifting of the Central Iranian Block (CIB) separated from Arabia and Gondwana during Late Permian - Early Triassic time. This realm travelled to the north to creation of the Neo-Tethyan oceanic lithosphere. The subduction of the Neo-Tethys could start to the south of the Central Iranian Block at Late Triassic to Plio-Quaternary time. The subduction of the Neo - Tethyan ocean beneath the active continental margin of the Iranian block was established by arc magmatism and back - arc spreading. These magmatic activities are marked from SW to NE by the presence of: calc-alkaline arc magmatism from Late Triassic to Late Jurassic in the Sanandaj-Sirjan Zone (SSZ), back - arc spreading with Late Cretaceous in the Esfandagheh Colour Melange Zone (ECMZ), back-arc spreading with Late Cretaceous - Palaeocene Nain-Baft Ophiolitic Belt (NBOB) and calc-alkaline arc magmatism from Eocene to Plio-Quaternary in the Urumieh-Dokhtar Magmatic Zone (UDMZ). Urumieh-Dokhtar magmatic zone has been considered as a place for the main magmatic activities in the Central Iranian continent in the Cenozoic age. This magmatic arc is situated to the North of the Mesozoic arc of the Sanandaj-Sirjan zone and the back-arc basin of the Central Iranian Block of Cretaceous age. During Oligocene-Miocene time the magmatic activity favored to alkaline magmatism. Geochemical data confirm the presence of transtensional tectonic setting along the Urumieh-Dokhtar magmatic zone, opened during Paleogene and early Neogene due to the collision of the Arabia platform and Central Iranian continent. These magmatic activities are linked to the subduction of the Neo-Tethys to the North below the CIB, followed by the Paleogene collision and continental subduction of the Gondwana (Arabia) beneath the CIB along the Main Zagros Thrust (MZT). Keywords: Neo - Tethys; Gondwana; Central Iranian Block (CIB); Sanandaj-Sirjan Zone (SSZ); Esfandagheh Colour Melange

  14. Factors influencing benthic bacterial abundance, biomass, and activity on the northern continental margin and deep basin of the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Deming, Jody W.; Carpenter, Shelly D.

    2008-12-01

    As part of a larger project on the deep benthos of the Gulf of Mexico, an extensive data set on benthic bacterial abundance ( n>750), supplemented with cell-size and rate measurements, was acquired from 51 sites across a depth range of 212-3732 m on the northern continental slope and deep basin during the years 2000, 2001, and 2002. Bacterial abundance, determined by epifluorescence microscopy, was examined region-wide as a function of spatial and temporal variables, while subsets of the data were examined for sediment-based chemical or mineralogical correlates according to the availability of collaborative data sets. In the latter case, depth of oxygen penetration helped to explain bacterial depth profiles into the sediment, but only porewater DOC correlated significantly (inversely) with bacterial abundance ( p<0.05, n=24). Other (positive) correlations were detected with TOC, C/N ratios, and % sand when the analysis was restricted to data from the easternmost stations ( p<0.05, n=9-12). Region-wide, neither surface bacterial abundance (3.30-16.8×10 8 bacteria cm -3 in 0-1 cm and 4-5 cm strata) nor depth-integrated abundance (4.84-17.5×10 13 bacteria m -2, 0-15 cm) could be explained by water depth, station location, sampling year, or vertical POC flux. In contrast, depth-integrated bacterial biomass, derived from measured cell sizes of 0.027-0.072 μm 3, declined significantly with station depth ( p<0.001, n=56). Steeper declines in biomass were observed for the cross-slope transects (when unusual topographic sites and abyssal stations were excluded). The importance of resource changes with depth was supported by the positive relationship observed between bacterial biomass and vertical POC flux, derived from measures of overlying productivity, a relationship that remained significant when depth was held constant (partial correlation analysis, p<0.05, df=50). Whole-sediment incubation experiments under simulated in situ conditions, using 3H-thymidine or 14C

  15. Great earthquakes in low strain rate continental interiors: An example from SE Kazakhstan

    NASA Astrophysics Data System (ADS)

    Campbell, G. E.; Walker, R. T.; Abdrakhmatov, K.; Jackson, J.; Elliott, J. R.; Mackenzie, D.; Middleton, T.; Schwenninger, J.-L.

    2015-08-01

    The Lepsy fault of the northern Tien Shan, SE Kazakhstan, extends E-W 120 km from the high mountains of the Dzhungarian Ala-tau, a subrange of the northern Tien Shan, into the low-lying Kazakh platform. It is an example of an active structure that connects a more rapidly deforming mountain region with an apparently stable continental region and follows a known Palaeozoic structure. Field-based and satellite observations reveal an ˜10 m vertical offset exceptionally preserved along the entire length of the fault. Geomorphic analysis and age control from radiocarbon and optically stimulated luminescence dating methods indicate that the scarp formed in the Holocene and was generated by at least two substantial earthquakes. The most recent event, dated to sometime after ˜400 years B.P., is likely to have ruptured the entire ˜120 km fault length in a Mw 7.5-8.2 earthquake. The Lepsy fault kinematics were characterized using digital elevation models and high-resolution satellite imagery, which indicate that the predominant sense of motion is reverse right lateral with a fault strike, dip, and slip vector azimuth of ˜110°, 50°S, and 317-343°, respectively, which is consistent with predominant N-S shortening related to the India-Eurasia collision. In light of these observations, and because the activity of the Lepsy fault would have been hard to ascertain if it had not ruptured in the recent past, we note that the absence of known active faults within low-relief and low strain rate continental interiors does not always imply an absence of seismic hazard.

  16. H.R. 73: A Bill to protect the ecologically fragile coastal resources of south Florida by prohibiting offshore oil and gas activities and by cancelling Federal leases in the area of the Outer Continental Shelf adjacent to the south Florida coast. Introduced in the House of Representatives, One Hundred Fourth Congress, First session

    SciTech Connect

    1995-12-31

    This document contains H.R. 73, A Bill to protect the ecologically fragile coastal resources of south Florida by prohibiting offshore oil and gas activities and by cancelling Federal leases in the area of the Outer Continental Shelf adjacent to south Florida. This Bill was introduced in the House of Representatives, 104th Congress, First Session, January 4, 1995.

  17. 76 FR 2919 - Outer Continental Shelf Official Protraction Diagram and Supplemental Official Outer Continental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... Bureau of Ocean Energy Management, Regulation and Enforcement Outer Continental Shelf Official Protraction Diagram and Supplemental Official Outer Continental Shelf Block Diagrams AGENCY: Bureau of Ocean... American Datum of 1983 (NAD 83) Outer Continental Shelf Official Protraction Diagram and...

  18. Bioenergetics of Continental Serpentinites

    NASA Astrophysics Data System (ADS)

    Cardace, D.; Meyer-Dombard, D. R.

    2011-12-01

    Serpentinization is the aqueous alteration of ultramafic (Fe- and Mg-rich) rocks, resulting in secondary mineral assemblages of serpentine, brucite, iron oxyhydroxides and magnetite, talc, and possibly carbonate and silica-rich veins and other minor phases-all depending on the evolving pressure-temperature-composition of the system. The abiotic evolution of hydrogen and possibly organic compounds via serpentinization (McCollom and Bach, 2009) highlights the relevance of this geologic process to carbon and energy sources for the deep biosphere. Serpentinization may fuel life over long stretches of geologic time, throughout the global seabed and in exposed, faulted peridotite blocks (as at Lost City Hydrothermal Field, Kelley et al., 2005), and in obducted oceanic mantle units in ophiolites (e.g., Tiago et al., 2004). Relatively little work has been published on life in continental serpentinite settings, though they likely host a unique resident microbiota. In this work, we systematically model the serpentinizing fluid as an environmental niche. Reported field data for high and moderate pH serpentinizing fluids were modeled from Cyprus, the Philippines, Oman, Northern California, New Caledonia, Yugoslavia, Portugal, Italy, Newfoundland Canada, New Zealand, and Turkey. Values for Gibbs Energy of reaction (ΔGr), kJ per mole of electrons transferred for a given metabolism, are calculated for each field site. Cases are considered both for (1) modest assumptions of 1 nanomolar hydrogen and 1 micromolar methane, based on unpublished data for a similar northern California field site (Cardace and Hoehler, in prep.) and (2) an upper estimate of 10 nanomolar hydrogen and 500 micromolar methane. We survey the feasibility of microbial metabolisms for key steps in the nitrogen cycle, oxidation of sulfur in pyrite, iron oxidation or reduction reactions, sulfate reduction coupled to hydrogen or methane oxidation, methane oxidation coupled to the reduction of oxygen, and

  19. Continental crust: a geophysical approach

    SciTech Connect

    Meissner, R.

    1986-01-01

    This book develops an integrated and balanced picture of present knowledge of the continental crust. Crust and lithosphere are first defined, and the formation of crusts as a general planetary phenomenon is described. The background and methods of geophysical studies of the earth's crust and the collection of related geophysical parameters are examined. Creep and friction experiments and the various methods of radiometric age dating are addressed, and geophysical and geological investigations of the crustal structure in various age provinces of the continents are studied. Specific tectonic structures such as rifts, continental margins, and geothermal areas are discussed. Finally, an attempt is made to give a comprehensive view of the evolution of the continental crust and to collect and develop arguments for crustal accretion and recycling. 647 references.

  20. The continental drift convection cell

    NASA Astrophysics Data System (ADS)

    Whitehead, J. A.; Behn, Mark D.

    2015-06-01

    Continents on Earth periodically assemble to form supercontinents and then break up again into smaller continental blocks (the Wilson cycle). Previous highly developed numerical models incorporate fixed continents while others indicate that continent movement modulates flow. Our simplified numerical model suggests that continental drift is fundamental. A thermally insulating continent is anchored at its center to mantle flow on an otherwise stress-free surface for infinite Prandtl number cellular convection with constant material properties. Rayleigh numbers exceed 107, while continent widths and chamber lengths approach Earth's values. The Wilson cycle is reproduced by a unique, rugged monopolar "continental drift convection cell." Subduction occurs at the cell's upstream end with cold slabs dipping at an angle beneath the moving continent (as found in many continent/subduction regions on Earth). Drift enhances vertical heat transport up to 30%, especially at the core-mantle boundary, and greatly decreases lateral mantle temperature differences.

  1. Subduction of lower continental crust beneath the Pamir imaged by receiver functions from the seismological TIPAGE network

    NASA Astrophysics Data System (ADS)

    Schneider, F. M.; Yuan, X.; Schurr, B.; Mechie, J.; Sippl, C.; Kufner, S.; Haberland, C. A.; Minaev, V.; Oimahmadov, I.; Gadoev, M.; Abdybachaev, U.; Orunbaev, S.

    2013-12-01

    As the northwestern promontory of the Tibetan Plateau, the Pamir forms an outstanding part of the India-Asia convergence zone. The Pamir plateau has an average elevation of more than 4000 m surrounded by peaks exceeding 7000 m at its northern, eastern and southern borders. The Pamir is thought to consist of the same collage of continental terranes as Tibet. However, in this region the Indian-Asian continental collision presents an extreme situation since, compared to Tibet, in the Pamir a similar amount of north-south convergence has been accommodated within a much smaller distance. The Pamir hosts a zone of intermediate depth earthquakes being the seismic imprint of Earth's most spectacular active intra-continental subduction zone. We present receiver function (RF) images from the TIPAGE seismic profile giving evidence that the intermediate depth seismicity is situated within a subducted layer of lower continental crust: We observe a southerly dipping 10-15 km thick low-velocity zone (LVZ), that starts from the base of the crust and extends to a depth of more than 150 km enveloping the intermediate depth earthquakes that have been located with high precision from our local network records. In a second northwest to southeast cross section we observe that towards the western Pamir the dip direction of the LVZ bends to the southeast following the geometry of the intermediate depth seismic zone. Our observations imply that the complete arcuate intermediate depth seismic zone beneath the Pamir traces a slab of subducting Eurasian continental lower crust. These observations provide important implications for the geodynamics of continental collision: First, it shows that under extreme conditions lower crust can be brought to mantle depths despite its buoyancy, a fact that is also testified by the exhumation of ultra-high pressure metamorphic rocks. Recent results from teleseismic tomography show a signal of Asian mantle lithosphere down to 600 km depth, implying a great

  2. Subduction-Driven Recycling of Continental Margin Lithosphere

    NASA Astrophysics Data System (ADS)

    Levander, Alan; Bezada, Maximiliano; Niu, Fenglin; Palomeras, Imma; Thurner, Sally; Humphreys, Eugene; Carbonell, Ramon; Gallart, Josep; Schmitz, Michael; Miller, Meghan

    2015-04-01

    Subduction recycling of oceanic lithosphere, a central theme of plate tectonics, is relatively well understood, whereas recycling continental lithosphere is more difficult to recognize, and appears far more complicated. Delamination and localized convective downwelling are two widely recognized processes invoked to explain the removal of lithospheric mantle under or adjacent to orogenic belts. Here we describe another process that can lead to the loss of continental lithosphere adjacent to a subduction zone: Subducting oceanic plates can entrain and recycle lithospheric mantle from an adjacent continent and disrupt the continental lithosphere far inland from the subduction zone. Seismic images from recent dense broadband seismograph arrays in northeastern South America (SA) and in the western Mediterranean show higher than expected volumes of positive anomalies identified as the subducted Atlantic slab under northeastern SA, and the Alboran slab beneath the Gibraltar arc region (GA). The positive anomalies lie under and are aligned with the continental margins at depths greater than 200 km. Closer to the surface we find that the continental margin lithospheric mantle is significantly thinner than expected beneath the orogens adjacent to the subduction zones. The thinner than expected lithosphere extends inland as far as the edges of nearby cratonic cores. These observations suggest that subducting oceanic plates viscously entrain and remove continental mantle lithosphere from beneath adjacent continental margins, modulating the surface tectonics and pre-conditioning the margins for further deformation. The latter can include delamination of the entire lithospheric mantle, as around GA, inferred by results from active and passive seismic experiments. Viscous removal of continental margin lithosphere creates lithosphere-asthenosphere boundary (LAB) topography which can give rise to secondary downwellings under the continental interior far inland from the subduction

  3. Orogenic plateau magmatism of the Arabia-Eurasia collision zone

    NASA Astrophysics Data System (ADS)

    Allen, M. B.; Neill, I.; Kheirkhah, M.; van Hunen, J.; Davidson, J. P.; Meliksetian, Kh.; Emami, M. H.

    2012-04-01

    Magmatism is a common feature of high plateaux created during continental collision, but the causes remain enigmatic. Here we study Pliocene-Quaternary volcanics from the active Arabia-Eurasia collision zone, to determine the chemistry of these rocks and their relations to faulting and deeper lithospheric structure. The great majority of the centres lie within the overriding Eurasian plate in Iran, eastern Turkey and Armenia , implying that mantle fertilised by pre-collision subduction processes plays a significant role in magma generation. The composition of the Pliocene-Quaternary centres is extremely variable, ranging from OIB-like alkali basalts, to intermediate types resembling mature continental arc lavas, to potassic and even ultrapotassic lavas. These centres are erupted across a mosaic of pre-Cenozoic suture zones and heterogeneous lithospheric blocks. The chemical diversity implies a range of partial melting conditions operating on lithospheric and perhaps sub-lithospheric sources. Published data show a thick (>200 km) lithospheric keel beneath the Arabia-Eurasia suture, thinning to near normal thicknesses (~120 km) across much of central and northern Iran. Thin mantle lithosphere under eastern Turkey (max. ~30 km) may relate to the region's juvenile, accretionary lithosphere. These variable thicknesses are constraints on the cause of the melting in each area, and the degree of variation suggests that no one mechanism applies across the plateau. Various melting models have been suggested. Break-off of the subducted Neo-Tethyan oceanic slab is supported by tomographic data, which may have permitted melting related to adiabatic ascent of hot asthenosphere under areas where the lithosphere is thin. This seems a less plausible mechanism where the lithosphere is at normal or greater than normal thickness. The same problem applies to postulated lower lithosphere delamination. Isolated pull-aparts may account for the location of some centres, but are not

  4. Multi-stage barites in partially melted UHP eclogite: implications for fluid/melt activities during deep continental subduction in the Sulu orogenic belt

    NASA Astrophysics Data System (ADS)

    Wang, Songjie; Wang, Lu

    2015-04-01

    . Zr-in-rutile thermometry shows their formation temperature to be 586-664 oC at 1.5-2.5 GPa. Barite-bearing MS inclusions with Ba-bearing K-feldspar (type-II) connected by Kfs+Pl+Bt veinlets of in-situ phengite breakdown and thin barite veinlets along grain boundaries (type-III) are products of phengite breakdown and induced fluid flow during exhumation. These barites have witnessed the gradational separation process of melt/ fluid from miscibility on/above the second critical endpoint during UHP metamorphism, to immiscibility along the exhumation path of the subducted slab. Associated reactions from pyrite to hematite and goethite with the type-III barite ring surrounding the pyrite provide evidence for a local high oxygen fugacity environment during eclogite partial melting and subsequent melt/fluid crystallization processes. Moreover, large grain barite aggregations (type-IV) modified by amphibole+albite symplectite are most likely formed by release of molecular and hydroxyl water from anhydrous minerals of eclogite during high-grade amphibolite-facies retrogression. The growth of multi-stage barites in UHP eclogite further advances our understanding of fluid/melt transfer, crystallization processes along the subduction-exhumation path of the partially melted eclogite, broadening our knowledge of melt/fluid evolution within subduction-collision zones worldwide. REFERENCES Chen Y.X., et al., 2014, Lithos, 200, 1-21. Liu J.B., et al., 2000, Acta Petrologica Sinica 16(4), 482-484. Zeng L.S., et al., 2007, Chinese Science Bulletin, 52(21), 2995-3001. Gao X.Y., et al., 2012, Journal of Metamorphic Geology, 30(2), 193-212.

  5. Suture Dynamics of the Banda Arc Collision Zone: Geochemical and Age Analysis of Ultramafic and Mafic Bodies in Timor, Indonesia

    NASA Astrophysics Data System (ADS)

    Valenza, J. M.; Harris, R. A.; Spencer, C. J.; Hoiland, C. W.; Flores, J. A.

    2013-12-01

    New age and geochemical data confirm that most ultramafic bodies on the north coast of Timor are derived from the distal reaches of the Australian continental margin lower plate that was exhumed by extension during Late Paleozoic to Mesozoic rifting. The ultramafic bodies were accreted to Timor during Late Miocene to present arc-continent collision. One of the lherzolitic ultramafic bodies near Caicua was previously unknown, but yields clear isotopic indicators that it is kin to the Hili Manu mafic and ultramafic complex further to the west. Zircon grains from metagabbro of the Hili Manu complex have cores with mostly Early Permian ages and rims of Latest Miocene ages. Isotopic analysis indicates abyssal plain, or passive margin affinity of the Caicua ultramafic body. One important exception to this pattern are mafic and ultramafic bodies associated with the Ocussi volcanics, which yield Miocene and Pliocene ages and supra-subduction zone chemical signatures. The Ocussi body is clearly part of the upper plate of the collision and formed after collision initiated further to the east. It is also structurally higher than the Hili Manu complex and has no affinities with the Australian plate. This study documents that both the upper and lower plates of the active arc-continent collision contribute mafic and ultramafic rocks to the evolving suture zone between the Indo-Australian and Asian plates in the Banda Arc region.

  6. Measurement of the underlying event activity using charged-particle jets in proton-proton collisions at √{s}=2.76 TeV

    NASA Astrophysics Data System (ADS)

    Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Knünz, V.; König, A.; Krammer, M.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Cornelis, T.; de Wolf, E. A.; Janssen, X.; Knutsson, A.; Lauwers, J.; Luyckx, S.; Ochesanu, S.; Rougny, R.; van de Klundert, M.; van Haevermaet, H.; van Mechelen, P.; van Remortel, N.; van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; de Bruyn, I.; Deroover, K.; Heracleous, N.; Keaveney, J.; Lowette, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; van Doninck, W.; van Mulders, P.; van Onsem, G. P.; van Parijs, I.; Barria, P.; Caillol, C.; Clerbaux, B.; de Lentdecker, G.; Delannoy, H.; Dobur, D.; Fasanella, G.; Favart, L.; Gay, A. P. R.; Grebenyuk, A.; Lenzi, T.; Léonard, A.; Maerschalk, T.; Mohammadi, A.; Perniè, L.; Randle-Conde, A.; Reis, T.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Yonamine, R.; Zenoni, F.; Zhang, F.; Beernaert, K.; Benucci, L.; Cimmino, A.; Crucy, S.; Fagot, A.; Garcia, G.; Gul, M.; McCartin, J.; Ocampo Rios, A. A.; Poyraz, D.; Ryckbosch, D.; Salva, S.; Sigamani, M.; Strobbe, N.; Tytgat, M.; van Driessche, W.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bondu, O.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; da Silveira, G. G.; Delaere, C.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Mertens, A.; Nuttens, C.; Perrini, L.; Pin, A.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Beliy, N.; Caebergs, T.; Hammad, G. H.; Aldá Júnior, W. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Dos Reis Martins, T.; Hensel, C.; Mora Herrera, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; da Costa, E. M.; de Jesus Damiao, D.; de Oliveira Martins, C.; Fonseca de Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; de Souza Santos, A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Genchev, V.; Hadjiiska, R.; Iaydjiev, P.; Marinov, A.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Cheng, T.; Du, R.; Jiang, C. H.; Plestina, R.; Romeo, F.; Shaheen, S. M.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Asawatangtrakuldee, C.; Ban, Y.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Zou, W.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; Gomez Moreno, B.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Kadija, K.; Luetic, J.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Bodlak, M.; Finger, M.; Finger, M.; Aly, R.; Aly, S.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Lotfy, A.; Mahmoud, M. A.; Radi, A.; Sayed, A.; Calpas, B.; Kadastik, M.; Murumaa, M.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Zghiche, A.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Dahms, T.; Davignon, O.; Filipovic, N.; Florent, A.; Granier de Cassagnac, R.; Lisniak, S.; Mastrolorenzo, L.; Miné, P.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Regnard, S.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Goetzmann, C.; Le Bihan, A.-C.; Merlin, J. A.; Skovpen, K.; van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Bouvier, E.; Brochet, S.; Carrillo Montoya, C. A.; Chasserat, J.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Ruiz Alvarez, J. D.; Sabes, D.; Sgandurra, L.; Sordini, V.; Donckt, M. Vander; Verdier, P.; Viret, S.; Xiao, H.; Toriashvili, T.; Bagaturia, I.; Autermann, C.; Beranek, S.; Edelhoff, M.; Feld, L.; Heister, A.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Preuten, M.; Raupach, F.; Sammet, J.; Schael, S.; Schulte, J. F.; Verlage, T.; Weber, H.; Wittmer, B.; Zhukov, V.; Ata, M.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Klingebiel, D.; Knutzen, S.; Kreuzer, P.; Merschmeyer, M.; Meyer, A.; Millet, P.; Olschewski, M.; Padeken, K.; Papacz, P.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Erdogan, Y.; Flügge, G.; Geenen, H.; Geisler, M.; Hoehle, F.; Kargoll, B.; Kress, T.; Kuessel, Y.; Künsken, A.; Lingemann, J.; Nehrkorn, A.; Nowack, A.; Nugent, I. M.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Asin, I.; Bartosik, N.; Behnke, O.; Behrens, U.; Bell, A. J.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Choudhury, S.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Gunnellini, P.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Katsas, P.; Kieseler, J.; Kleinwort, C.; Korol, I.; Lange, W.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Marfin, I.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Nayak, A.; Ntomari, E.; Perrey, H.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Ribeiro Cipriano, P. M.; Roland, B.; Sahin, M. Ö.; Salfeld-Nebgen, J.; Saxena, P.; Schoerner-Sadenius, T.; Schröder, M.; Seitz, C.; Spannagel, S.; Trippkewitz, K. D.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Erfle, J.; Garutti, E.; Goebel, K.; Gonzalez, D.; Görner, M.; Haller, J.; Hoffmann, M.; Höing, R. 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T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Serban, A. T.; Spagnolo, P.; Squillacioti, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; D'Imperio, G.; Del Re, D.; Diemoz, M.; Gelli, S.; Jorda, C.; Longo, E.; Margaroli, F.; Meridiani, P.; Micheli, F.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Traczyk, P.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bellan, R.; Biino, C.; Cartiglia, N.; Costa, M.; Covarelli, R.; Degano, A.; Dellacasa, G.; Demaria, N.; Finco, L.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Musich, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. 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A.; Harder, K.; Harper, S.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Thomas, L.; Tomalin, I. R.; Williams, T.; Womersley, W. J.; Worm, S. D.; Baber, M.; Bainbridge, R.; Buchmuller, O.; Bundock, A.; Burton, D.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Cripps, N.; Dauncey, P.; Davies, G.; de Wit, A.; Della Negra, M.; Dunne, P.; Elwood, A.; Ferguson, W.; Fulcher, J.; Futyan, D.; Hall, G.; Iles, G.; Karapostoli, G.; Kenzie, M.; Lane, R.; Lucas, R.; Lyons, L.; Magnan, A.-M.; Malik, S.; Nash, J.; Nikitenko, A.; Pela, J.; Pesaresi, M.; Petridis, K.; Raymond, D. M.; Richards, A.; Rose, A.; Seez, C.; Sharp, P.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leggat, D.; Leslie, D.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Dittmann, J.; Hatakeyama, K.; Kasmi, A.; Liu, H.; Pastika, N.; Charaf, O.; Cooper, S. I.; Henderson, C.; Rumerio, P.; Avetisyan, A.; Bose, T.; Fantasia, C.; Gastler, D.; Lawson, P.; Rankin, D.; Richardson, C.; Rohlf, J.; St. John, J.; Sulak, L.; Zou, D.; Alimena, J.; Berry, E.; Bhattacharya, S.; Cutts, D.; Dhingra, N.; Ferapontov, A.; Garabedian, A.; Heintz, U.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Sagir, S.; Sinthuprasith, T.; Breedon, R.; Breto, G.; Calderon de La Barca Sanchez, M.; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Gardner, M.; Ko, W.; Lander, R.; Mulhearn, M.; Pellett, D.; Pilot, J.; Ricci-Tam, F.; Shalhout, S.; Smith, J.; Squires, M.; Stolp, D.; Tripathi, M.; Wilbur, S.; Yohay, R.; Cousins, R.; Everaerts, P.; Farrell, C.; Hauser, J.; Ignatenko, M.; Rakness, G.; Saltzberg, D.; Takasugi, E.; Valuev, V.; Weber, M.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Hanson, G.; Heilman, J.; Ivova Paneva, M.; Jandir, P.; Kennedy, E.; Lacroix, F.; Long, O. R.; Luthra, A.; Malberti, M.; Olmedo Negrete, M.; Shrinivas, A.; Sumowidagdo, S.; Wei, H.; Wimpenny, S.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; D'Agnolo, R. T.; Holzner, A.; Kelley, R.; Klein, D.; Letts, J.; MacNeill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Tu, Y.; Vartak, A.; Wasserbaech, S.; Welke, C.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Barge, D.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Flowers, K.; Franco Sevilla, M.; Geffert, P.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Incandela, J.; Justus, C.; McColl, N.; Mullin, S. D.; Richman, J.; Stuart, D.; Suarez, I.; To, W.; West, C.; Yoo, J.; Anderson, D.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Mott, A.; Newman, H. B.; Pena, C.; Pierini, M.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Azzolini, V.; Calamba, A.; Carlson, B.; Ferguson, T.; Iiyama, Y.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Ford, W. T.; Gaz, A.; Jensen, F.; Johnson, A.; Krohn, M.; Mulholland, T.; Nauenberg, U.; Smith, J. G.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chatterjee, A.; Chaves, J.; Chu, J.; Dittmer, S.; Eggert, N.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Sun, W.; Tan, S. M.; Teo, W. D.; Thom, J.; Thompson, J.; Tucker, J.; Weng, Y.; Wittich, P.; Abdullin, S.; Albrow, M.; Anderson, J.; Apollinari, G.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hanlon, J.; Hare, D.; Harris, R. M.; Hirschauer, J.; Hooberman, B.; Hu, Z.; Jindariani, S.; Johnson, M.; Joshi, U.; Jung, A. W.; Klima, B.; Kreis, B.; Kwan, S.; Lammel, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, T.; Lopes de Sá, R.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Martinez Outschoorn, V. I.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mishra, K.; Mrenna, S.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Prokofyev, O.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Whitbeck, A.; Yang, F.; Yin, H.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; di Giovanni, G. P.; Field, R. D.; Fisher, M.; Furic, I. K.; Hugon, J.; Konigsberg, J.; Korytov, A.; Low, J. F.; Ma, P.; Matchev, K.; Mei, H.; Milenovic, P.; Mitselmakher, G.; Muniz, L.; Rank, D.; Shchutska, L.; Snowball, M.; Sperka, D.; Wang, S.; Yelton, J.; Hewamanage, S.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, J. R.; Adams, T.; Askew, A.; Bochenek, J.; Diamond, B.; Haas, J.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Khatiwada, A.; Prosper, H.; Veeraraghavan, V.; Weinberg, M.; Bhopatkar, V.; Hohlmann, M.; Kalakhety, H.; Mareskas-Palcek, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Kurt, P.; O'Brien, C.; Sandoval Gonzalez, I. D.; Silkworth, C.; Turner, P.; Varelas, N.; Wu, Z.; Zakaria, M.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tan, P.; Tiras, E.; Wetzel, J.; Yi, K.; Anderson, I.; Barnett, B. A.; Blumenfeld, B.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Xin, Y.; Baringer, P.; Bean, A.; Benelli, G.; Bruner, C.; Gray, J.; Kenny, R. P.; Majumder, D.; Malek, M.; Murray, M.; Noonan, D.; Sanders, S.; Stringer, R.; Wang, Q.; Wood, J. S.; Chakaberia, I.; Ivanov, A.; Kaadze, K.; Khalil, S.; Makouski, M.; Maravin, Y.; Saini, L. K.; Skhirtladze, N.; Svintradze, I.; Toda, S.; Lange, D.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Kellogg, R. G.; Kolberg, T.; Kunkle, J.; Lu, Y.; Mignerey, A. C.; Pedro, K.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Baty, A.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; Demiragli, Z.; Di Matteo, L.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; McGinn, C.; Niu, X.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Stephans, G. S. F.; Sumorok, K.; Varma, M.; Velicanu, D.; Veverka, J.; Wang, J.; Wang, T. W.; Wyslouch, B.; Yang, M.; Zhukova, V.; Dahmes, B.; Finkel, A.; Gude, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Keller, J.; Knowlton, D.; Kravchenko, I.; Lazo-Flores, J.; Meier, F.; Monroy, J.; Ratnikov, F.; Siado, J. E.; Snow, G. R.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira de Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Zhang, J.; Hahn, K. A.; Kubik, A.; Mucia, N.; Odell, N.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Sung, K.; Trovato, M.; Velasco, M.; Won, S.; Brinkerhoff, A.; Dev, N.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Lynch, S.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Pearson, T.; Planer, M.; Ruchti, R.; Smith, G.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Hart, A.; Hill, C.; Hughes, R.; Kotov, K.; Ling, T. Y.; Liu, B.; Luo, W.; Puigh, D.; Rodenburg, M.; Winer, B. L.; Wulsin, H. W.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Koay, S. A.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Palmer, C.; Piroué, P.; Quan, X.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zuranski, A.; Malik, S.; Barnes, V. E.; Benedetti, D.; Bortoletto, D.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, K.; Kress, M.; Leonardo, N.; Miller, D. H.; Neumeister, N.; Primavera, F.; Radburn-Smith, B. C.; Shi, X.; Shipsey, I.; Silvers, D.; Sun, J.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Zablocki, J.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Goldenzweig, P.; Han, J.; Harel, A.; Hindrichs, O.; Khukhunaishvili, A.; Petrillo, G.; Verzetti, M.; Demortier, L.; Arora, S.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Lath, A.; Panwalkar, S.; Park, M.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Foerster, M.; Riley, G.; Rose, K.; Spanier, S.; York, A.; Bouhali, O.; Castaneda Hernandez, A.; Dalchenko, M.; de Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Krutelyov, V.; Montalvo, R.; Mueller, R.; Osipenkov, I.; Pakhotin, Y.; Patel, R.; Perloff, A.; Roe, J.; Rose, A.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Undleeb, S.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Lin, C.; Neu, C.; Wolfe, E.; Wood, J.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Carlsmith, D.; Cepeda, M.; Christian, A.; Dasu, S.; Dodd, L.; Duric, S.; Friis, E.; Gomber, B.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ross, I.; Ruggles, T.; Sarangi, T.; Savin, A.; Sharma, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.

    2015-09-01

    A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region (| η jet| < 2) and with transverse momentum 1 ≤ p T jet < 100 GeV. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 TeV with the CMS experiment at the LHC. The UE activity is measured as a function of p T jet in terms of the average multiplicity and scalar sum of transverse momenta ( p T) of charged particles, with | η| < 2 and p T > 0.5 GeV, in the azimuthal region transverse to the highest p T jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated. The measurements are compared to previous results at 0.9 and 7 TeV, and to predictions of several Monte Carlo event generators, providing constraints on the modelling of the UE dynamics. [Figure not available: see fulltext.

  7. Measurement of the underlying event activity using charged-particle jets in proton-proton collisions at $\\sqrt{s}$ = 2.76 TeV

    SciTech Connect

    Khachatryan, V.

    2015-09-21

    A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region (|η jet| < 2) and with transverse momentum 1 ≤ pT jet < 100 GeV. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 TeV with the CMS experiment at the LHC. The UE activity is measured as a function of pT jet in terms of the average multiplicity and scalar sum of transverse momenta (pT) of charged particles, with |η| < 2 and pT > 0.5 GeV, in the azimuthal region transverse to the highest pT jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated. As a result, the measurements are compared to previous results at 0.9 and 7 TeV, and to predictions of several Monte Carlo event generators, providing constraints on the modelling of the UE dynamics

  8. Measurement of the underlying event activity using charged-particle jets in proton-proton collisions at $$\\sqrt{s}$$ = 2.76 TeV

    DOE PAGESBeta

    Khachatryan, V.

    2015-09-21

    A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region (|η jet| < 2) and with transverse momentum 1 ≤ pT jet < 100 GeV. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 TeV with the CMS experiment at the LHC. The UE activity is measured as a function of pT jet in terms of the average multiplicity and scalar sum of transverse momenta (pT) of charged particles, with |η| < 2 and pT > 0.5 GeV, in the azimuthal regionmore » transverse to the highest pT jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated. As a result, the measurements are compared to previous results at 0.9 and 7 TeV, and to predictions of several Monte Carlo event generators, providing constraints on the modelling of the UE dynamics« less

  9. Deep Continental Crustal Earthquakes and Lithospheric Structure: A Global Synthesis

    NASA Astrophysics Data System (ADS)

    Devlin, S.; Isacks, B. L.

    2007-12-01

    measurements indicate that lower crustal earthquakes exist within continental regions experiencing youthful (generally Neogene to present) tectonism typically with < 15 % strain. We propose a model that describes relative continental deformation and corresponding seismogenic thickness. In stable seismogenic regions, earthquakes are limited to depths where near-surface derived fluids can induce activity and therefore TS < 25 km. As continental lithosphere passes into an intermediate state of deformation, fluids from the near surface and melts formed in situ or derived from the mantle can act to seismically activate the entire continental crust. As deformation continues, percent strains can reach 100 % or more, mantle lithosphere is typically thinned or absent, and the lower crust via heating and/or sufficient weakening becomes aseismic.

  10. Fire activity inside and outside protected areas in Sub-Saharan Africa: a continental analysis of fire and its implications for biodiversity and management

    NASA Astrophysics Data System (ADS)

    Palumbo, Ilaria; Gregoire, Jean-Marie; Simonetti, Dario; Punga, Mihkel; Dubois, Gregoire

    2010-05-01

    Fire is an important ecological factor in many natural ecosystems. Without doubt one of the biomes with the highest fire activity in the world is the African savannah. Savannahs have evolved with fires since climate in these regions is characterized by definite dry and wet seasons that create the conditions for burning. During the wet months the herbaceous vegetation shows a quick growth, followed by a long dry period during which the abundant build-up of fine materials becomes highly flammable and most of fires occur. Animals and plants are adapted to these conditions and their lives depend on recurrent fires. In this context fire becomes an essential element to promote biodiversity and nature conservation. Park managers are using programmed fires as a tool to maintain the habitats and favorable conditions to the animal communities. Satellite products like burned areas and active fire maps are a valuable mean to analyze the fire activity and provide support to experts working for conservation and natural resource management. In the framework of the Digital Observatory for Protected Areas (DOPA), the MONDE group (Monitoring Natural Resources for Development) of the Joint Research Centre of the European Commission is using satellite products to analyze the fire occurrence and its effects on protected areas located in sub-Saharan Africa. Information on the fire activity was derived from the MODIS fire products (active fires and burned areas) and allows the DOPA to provide support to park managers as well as to experts working for conservation and natural resource management. We assessed 741 protected areas classified by the IUCN (International Union for Conservation of Nature) with a level of protection between class I and IV. The MODIS datasets are available since the year 2000 and were used to characterize the spatio-temporal distribution of fires over a period of 10 years. Information on fire activity was extracted for the protected areas and a 25km buffer zone

  11. Fire activity inside and outside protected areas in Sub-Saharan Africa: a continental analysis of fire and its implications for biodiversity and land management

    NASA Astrophysics Data System (ADS)

    Palumbo, Ilaria; Gregoire, Jean-Marie; Simonetti, Dario; Punga, Mihkel; Dubois, Gregoire

    2010-05-01

    Fire is an important ecological factor in many natural ecosystems. Without doubt one of the biomes with the highest fire activity in the world is the African savannah. Savannahs have evolved with fires since climate in these regions is characterized by definite dry and wet seasons that create the conditions for burning. During the wet months the herbaceous vegetation shows a quick growth, followed by a long dry period during which the abundant build-up of fine materials becomes highly flammable and most of fires occur. Animals and plants are adapted to these conditions and their lives depend on recurrent fires. In this context fire becomes an essential element to promote biodiversity and nature conservation. Park managers are using programmed fires as a tool to maintain the habitats and favorable conditions to the animal communities. Satellite products like burned areas and active fire maps are a valuable mean to analyze the fire activity and provide support to experts working for conservation and natural resource management. In the framework of the Digital Observatory for Protected Areas (DOPA), the MONDE group (Monitoring Natural Resources for Development) of the Joint Research Centre of the European Commission is using satellite products to analyze the fire occurrence and its effects on protected areas located in sub-Saharan Africa. Information on the fire activity was derived from the MODIS fire products (active fires and burned areas) and allows the DOPA to provide support to park managers as well as to experts working for conservation and natural resource management. We assessed 741 protected areas classified by the IUCN (International Union for Conservation of Nature) with a level of protection between class I and IV. The MODIS datasets are available since the year 2000 and were used to characterize the spatio-temporal distribution of fires over a period of 10 years. Information on fire activity was extracted for the protected areas and a 25km buffer zone

  12. Mantle Dynamics of Australia-Banda Arc Collision as Inferred from Shear Wave Splitting Analysis of Teleseismic and Local Slab Events

    NASA Astrophysics Data System (ADS)

    Harris, C. W.; Miller, M. S.; O'Driscoll, L.; Porritt, R. W.; Roosmawati, N.; Widiyantoro, S.

    2015-12-01

    Arc-continent collision is an important factor in continent building, orogensis, and ocean closure, yet the details associated with it are not fully understood. East-Timor and the Nusa Tenggara Timur region of Indonesia provide a unique setting to study a young arc-continent collision (~8 Ma) and incipient orogenesis. The NSF funded Banda Arc project affords a rare opportunity to investigate unconstrained processes such as active continental subduction and slab rupture beneath a regional deployment of broadband seismometers. We use data from 35 broadband sensors to analyze seismic anisotropy through measuring shear wave splitting. These stations span the roughly east-west transition from normal oceanic subduction at the Sunda Arc to collision at the Banda Arc, and cross areas associated with back-arc thrusting, arc volcanism, extinct volcanism and a rapidly exhuming forearc. Thirty of the sensors used in the analysis are temporary stations installed by our research team in 2014 and will remain in the field until 2016 or later. The remaining stations are part of the open-access GFZ GEOFON global seismic network. We present preliminary shear wave splitting results for teleseismic (*KS core phases) and local (direct S phase) arrivals in order to inspect the sub-slab mantle and the supra-slab mantle wedge for anisotropic patterns related to olivine flow fabric. These results can be used to assess regional strain linked to ongoing collision and may elucidate any slab tearing that has resulted from the (partial) subduction of buoyant continental material of Australian affinity. Presently, we observe a trend of primarily trench-parallel sub-slab fast polarization directions and perhaps more complicated anisotropy in the mantle wedge. Relative to the trench, there appears to be more spatial variation in fast axis orientation for direct arrivals than teleseismic phases. We discuss how the interpretation of our initial results provides insight into the mantle dynamics of the

  13. Ternary drop collisions

    NASA Astrophysics Data System (ADS)

    Hinterbichler, Hannes; Planchette, Carole; Brenn, Günter

    2015-10-01

    It has been recently proposed to use drop collisions for producing advanced particles or well-defined capsules, or to perform chemical reactions where the merged drops constitute a micro-reactor. For all these promising applications, it is essential to determine whether the merged drops remain stable after the collision, forming a single entity, or if they break up. This topic, widely investigated for binary drop collisions of miscible and immiscible liquid, is quite unexplored for ternary drop collisions. The current study aims to close this gap by experimentally investigating collisions between three equal-sized drops of the same liquid arranged centri-symmetrically. Three drop generators are simultaneously operated to obtain controlled ternary drop collisions. The collision outcomes are observed via photographs and compared to those of binary collisions. Similar to binary collisions, a regime map is built, showing coalescence and bouncing as well as reflexive and stretching separation. Significant differences are observed in the transitions between these regimes.

  14. Estimation of continental precipitation recycling

    NASA Technical Reports Server (NTRS)

    Brubaker, Kaye L.; Entekhabi, Dara; Eagleson, P. S.

    1993-01-01

    The total amount of water that precipitates on large continental regions is supplied by two mechanisms: 1) advection from the surrounding areas external to the region and 2) evaporation and transpiration from the land surface within the region. The latter supply mechanism is tantamount to the recycling of precipitation over the continental area. The degree to which regional precipitation is supplied by recycled moisture is a potentially significant climate feedback mechanism and land surface-atmosphere interaction, which may contribute to the persistence and intensification of droughts. Gridded data on observed wind and humidity in the global atmosphere are used to determine the convergence of atmospheric water vapor over continental regions. A simplified model of the atmospheric moisture over continents and simultaneous estimates of regional precipitation are employed to estimate, for several large continental regions, the fraction of precipitation that is locally derived. The results indicate that the contribution of regional evaporation to regional precipitation varies substantially with location and season. For the regions studied, the ratio of locally contributed to total monthly precipitation generally lies between 0. 10 and 0.30 but is as high as 0.40 in several cases.

  15. Late Cretaceous-Cenozoic subduction-collision history of the Southern Neotethys: new evidence from the Çağlayancerit area, SE Turkey

    NASA Astrophysics Data System (ADS)

    Akıncı, Ahmet Can; Robertson, Alastair H. F.; Ünlügenç, Ulvi Can

    2016-01-01

    Evidence of the subduction-collision history of the S Neotethys is well exposed in the frontal part of the SE Anatolian thrust belt and the adjacent Arabian continental margin. The foreland succession in the study area begins with Eocene shelf carbonates, ranging from shallow marine to deeper marine, without sedimentary input from the Tauride continent to the north. After a regional hiatus (Oligocene), sedimentation resumed during the Early Miocene with terrigenous gravity-flow deposition in the north (Lice Formation) and shallow-marine carbonates further south. Clastic detritus was derived from the Tauride continent and oceanic accretionary material. The base of the overriding Tauride allochthon comprises ophiolite-derived debris flows, ophiolite-related mélange and dismembered ophiolitic rocks. Above this, the regional-scale Bulgurkaya sedimentary mélange (an olistostrome) includes blocks and dismembered thrust sheets of metamorphic rocks, limestone and sandstone, which include Late Cretaceous and Eocene foraminifera. The matrix is mainly strongly deformed Eocene-Oligocene mudrocks, hemipelagic marl and sandstone turbidites. The thrust stack is topped by a regionally extensive thrust sheet (Malatya metamorphic unit), which includes greenschist facies marble, calcschist, schist and phyllite, representing Tauride continental crust. Beginning during the Late Mesozoic, the S Neotethys subducted northwards beneath a backstop represented by the Tauride microcontinent (Malatya metamorphic unit). Ophiolites formed within the S Neotethys and accreted to the Tauride active margin. Large-scale sedimentary mélange developed along the Tauride active margin during Eocene-Oligocene. On the Arabian margin, a sedimentary hiatus and tilting (Oligocene) is interpreted to record initial continental collision. The Early Miocene terrigenous gravity flows represent a collision-related flexural foreland basin. Southward overthrusting of the Tauride allochthon took place during Early

  16. Seismotectonics of the southern boundary of Anatolia, eastern Mediterranean region: Subduction, collision, and arc jumping

    NASA Astrophysics Data System (ADS)

    Rotstein, Yair; Kafka, Alan L.

    1982-09-01

    The pattern of seismicity and fault plane solutions of earthquakes are used to outline the tectonic features of the southern boundary of Anatolia in the eastern Mediterranean and southeastern Turkey. The results of this study show that this boundary is composed of two distinct parts. One, in southeastern Turkey and Syria, is a wide and complex zone of continental collision. The other, in the Levantine basin of the eastern Mediterranean, is a zone of oceanic subduction. In the region of continental collision three zones of seismicity are observed. Most of the seismic activity in this region follows the Bitlis zone and is associated with a zone of thrusting and mountain building. This appears to be the zone of most active deformation and plate consumption in the plate boundary region between Arabia and Turkey. A less active zone of seismicity to the north of the Bitlis zone is interpreted to have been more active in the past whereas another active zone of seismicity to the south is interpreted to be a zone which may be more active in the future as the main zone of plate consumption jumps to the south. In the subduction zone of the eastern Mediterranean the depth of the subducted slab and the rate of seismicity generally increase from east to west. The zone of present-day convergence between Africa and Turkey in the Levantine basin can be best outlined by the northern edge of the Mediterranean ridge. The subduction zone in this area sequentially jumps to the south as small continental fragments collide with existing zones of subduction. Deep seismic activity near the Gulf of Antalya is associated with a detached subducted slab north of the Anaximander Mountains that is distinctly different from the seismic trend which is associated with present-day active subduction. The plate boundary between Africa and Turkey at the center of the Levantine basin appears to have shifted to the south of the Anaximander Mountains and Florence rise. Most of the focal mechanisms of the

  17. Glaciomarine sedimentation and bottom current activity on the north-western and northern continental margins of Svalbard during the late Quaternary

    NASA Astrophysics Data System (ADS)

    Chauhan, Teena; Noormets, Riko; Rasmussen, Tine L.

    2016-04-01

    Palaeo-bottom current strength of the West Spitsbergen Current (WSC) and the influence of the Svalbard-Barents Sea Ice Sheet (SBIS) on the depositional environment along the northern Svalbard margins are poorly known. Two gravity cores from the southern Yermak Plateau and the upper slope north of Nordaustlandet, covering marine isotope stage (MIS) 1 to MIS 5, are investigated. Five lithofacies, based on grain size distribution, silt/clay ratio, content and mean of sortable silt (SS), are distinguished to characterise the contourite-dominated sedimentary environments. In addition, depositional environments are described using total organic carbon (TOC), total sulphur (TS) and calcium carbonate (CaCO3) contents of sediments. Facies A, containing coarse SS, suggests strong bottom current activity and good bottom water ventilation conditions as inferred from low TOC content. This facies was deposited during the glacial periods MIS 4, MIS 2 and during the late Holocene. Facies B is dominated by fine SS indicating weak bottom current and poor ventilation (cf. high TOC content of 1.2-1.6%), and correlates with the MIS 4/3 and MIS 2/1 transition periods. With an equal amount of clay and sand, fine SS and high content of TOC, facies C indicates reduced bottom current strength for intervals with sediment supply from proximal sources such as icebergs, sea ice or meltwater discharge. This facies was deposited during the last glacial maximum. Facies D represents mass-flow deposits on the northern Svalbard margin attributed to the SBIS advance at or near the shelf edge. Facies E sediments indicating moderate bottom current strength were deposited during MIS 5 and MIS 3, and during parts of MIS 2. This first late Quaternary proxy record of the WSC flow and sedimentation history from the northern Svalbard margin suggests that the oceanographic conditions and ice sheet processes have exerted first-order control on sediment properties.

  18. Chlorine activation within urban or power plant plumes: Vertically resolved ClNO2 and Cl2 measurements from a tall tower in a polluted continental setting

    NASA Astrophysics Data System (ADS)

    Riedel, Theran P.; Wagner, Nicholas L.; Dubé, William P.; Middlebrook, Ann M.; Young, Cora J.; Öztürk, Fatma; Bahreini, Roya; Vandenboer, Trevor C.; Wolfe, Daniel E.; Williams, Eric J.; Roberts, James M.; Brown, Steven S.; Thornton, Joel A.

    2013-08-01

    chloride (ClNO2) is a chlorine atom source and reactive nitrogen reservoir formed during the night by heterogeneous reactions of dinitrogen pentoxide on chloride-containing aerosol particles. The main factors that influence ClNO2 production include nitrogen oxides, ozone, aerosol surface area, soluble chloride, and ambient relative humidity. Regions with strong anthropogenic activity therefore have large ClNO2 formation potential even inland of coastal regions due to transport or local emissions of soluble chloride. As part of the Nitrogen, Aerosol Composition, and Halogens on a Tall Tower field study, we report wintertime vertically resolved ClNO2 and molecular chlorine (Cl2) measurements taken on a 300 m tall tower located at NOAA's Boulder Atmospheric Observatory in Weld County, CO, during February and March of 2011. Gas and particle phase measurements aboard the tower carriage allowed for a detailed description of the chemical state of the nocturnal atmosphere as a function of height. These observations show significant vertical structure in ClNO2 and Cl2 mixing ratios that undergo dynamic changes over the course of a night. Using these measurements, we focus on two distinct combustion plume events where ClNO2 mixing ratios reached 600 and 1300 parts per trillion by volume, respectively, aloft of the nocturnal surface layer. We infer ClNO2 yields from N2O5-aerosol reactions using both observational constraints and box modeling. The derived yields in these plumes suggest efficient ClNO2 production compared to the campaign average, where in-plume yields range from 0.3 to 1; the campaign average yield in the boundary layer is 0.05 ± 0.15, with substantial night-to-night and within night variability similar to previous measurements in this region.

  19. Inheritance of pre-existing weakness in continental breakup: 3D numerical modeling

    NASA Astrophysics Data System (ADS)

    Liao, Jie; Gerya, Taras

    2013-04-01

    The whole process of continental rifting to seafloor spreading is one of the most important plate tectonics on the earth. There are many questions remained related to this process, most of which are poorly understood, such as how continental rifting transformed into seafloor spreading? How the curved oceanic ridge developed from a single straight continental rift? How the pre-existing weakness in either crust or lithospheric mantle individually influences the continental rifting and oceanic spreading? By employing the state-of-the-art three-dimensional thermomechanical-coupled numerical code (using Eulerian-Lagrangian finite-difference method and marker-in-cell technic) (Gerya and Yuen, 2007), which can model long-term plate extension and large strains, we studied the whole process of continental rifting to seafloor spreading based on the following question: How the pre-existing lithospheric weak zone influences the continental breakup? Continental rifts do not occur randomly, but like to follow the pre-existing weakness (such as fault zones, suture zones, failed rifts, and other tectonic boundaries) in the lithosphere, for instance, the western branch of East African Rift formed in the relatively weak mobile belts along the curved western border of Tanzanian craton (Corti et al., 2007; Nyblade and Brazier, 2002), the Main Ethiopian Rift developed within the Proterozoic mobile belt which is believed to represent a continental collision zone (Keranen and Klemperer, 2008),the Baikal rift formed along the suture between Siberian craton and Sayan-Baikal folded belt (Chemenda et al., 2002). The early stage formed rift can be a template for the future rift development and continental breakup (Keranen and Klemperer, 2008). Lithospheric weakness can either reduce the crustal strength or mantle strength, and leads to the crustal or mantle necking (Dunbar and Sawyer, 1988), which plays an important role on controlling the continental breakup patterns, such as controlling the

  20. Yellowstone hotspot-continental lithosphere interaction

    NASA Astrophysics Data System (ADS)

    Jean, Marlon M.; Hanan, Barry B.; Shervais, John W.

    2014-03-01

    The Snake River Plain represents 17 m.y. of volcanic activity that took place as the North American continent migrated over a relatively fixed magma source, or hotspot. We present new Pb, Sr, and Nd data for a suite of 25 basalts collected from Western and Central Snake River Plain (SRP). The new isotope data, combined with previously published data from the SRP, provide a traverse of the Wyoming craton margin, from the 87Sr/86Sr = 0.706 line boundary of western SRP with Phanerozoic accreted terranes, east through the central and eastern SRP, to the Yellowstone Plateau. Low-K basalts from the western SRP, overlain by high-K basalts, provide a temporal record of regional source variation from ∼16.8 to 0.2 Ma. Principal Component Analysis (PCA) of the new and previously published SRP basalt Pb isotopes reveals that >97% of the total variability is accounted for by mixing between three end-members and is consistent with a sublithospheric Yellowstone hotspot mantle source with a radiogenic isotope composition similar to the mantle source of the early Columbia River Basalt Group (CRBG) and two continental lithosphere end-members, heterogeneous in age and composition. We use the SRP Pb, Sr, and Nd isotope data to model the Yellowstone Hotspot-continental lithosphere interaction by three component mixing between two continental lithospheric components, Archean lithosphere (CL1) that represents older lithosphere underlying the Yellowstone Plateau in the east, and Paleoproterozoic lithosphere (CL2) representing the younger lithosphere underlying the SRP in the west near the craton margin, and a sublithospheric end-member, representing the Yellowstone hotspot (PL). The results suggest a continuous flow of PL material westward as the NA continental lithosphere migrated over the upwelling hotspot along a shoaling gradient in the sub-continental mantle lithosphere. The model shows a decrease in Total Lithosphere end-members (CL1 + CL2) and the Lithosphere Ratio (CL1/CL2

  1. Collision experiments with fullerenes

    NASA Astrophysics Data System (ADS)

    Campbell, E. E. B.; Ehlich, R.; Westerburg, M.; Hertel, I. V.

    1993-12-01

    Relative fragmentation cross sections for fullerene ion collisions with rare gas atoms and SF6 are presented over a range of collision energies. Structure in the cross sections and threshold energy determinations can shed some light on the fragmentation dynamics. Cluster cluster collisions with fullerenes are also described which show evidence of fusion reactions.

  2. Comprehensive lake dynamics mapping at continental scales using Landsat 8

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inland lakes, important water resources, play a crucial role in the global water cycle and are sensitive to global warming and human activities. There clearly is a pressing need to understand temporal and spatial variations of lakes at global and continental scales. The recent operation of Landsat...

  3. Ediacaran 2,500-km-long synchronous deep continental subduction in the West Gondwana Orogen.

    PubMed

    Ganade de Araujo, Carlos E; Rubatto, Daniela; Hermann, Joerg; Cordani, Umberto G; Caby, Renaud; Basei, Miguel A S

    2014-01-01

    The deeply eroded West Gondwana Orogen is a major continental collision zone that exposes numerous occurrences of deeply subducted rocks, such as eclogites. The position of these eclogites marks the suture zone between colliding cratons, and the age of metamorphism constrains the transition from subduction-dominated tectonics to continental collision and mountain building. Here we investigate the metamorphic conditions and age of high-pressure and ultrahigh-pressure eclogites from Mali, Togo and NE-Brazil and demonstrate that continental subduction occurred within 20 million years over at least a 2,500-km-long section of the orogen during the Ediacaran. We consider this to be the earliest evidence of large-scale deep-continental subduction and consequent appearance of Himalayan-scale mountains in the geological record. The rise and subsequent erosion of such mountains in the Late Ediacaran is perfectly timed to deliver sediments and nutrients that are thought to have been necessary for the subsequent evolution of sustainable life on Earth. PMID:25319269

  4. Active tectonics of the Binalud Mountains, a key puzzle segment to describe Quaternary deformations at the northeastern boundary of the Arabia-Eurasia collision

    NASA Astrophysics Data System (ADS)

    Shabanian, Esmaeil; Bellier, Olivier; Siame, Lionel L.; Abbassi, Mohammad R.; Leanni, Laetitia; Braucher, Régis; Farbod, Yassaman; Bourlès, Didier L.

    2010-05-01

    In northeast Iran, the Binalud Mountains accommodate part of active convergence between the Arabian and Eurasian plates. This fault-bounded mountain range has been considered a key region to describe Quaternary deformations at the northeastern boundary of the Arabia-Eurasia collision. But, the lack of knowledge on active faulting hampered evaluating the geological reliability of tectonic models describing the kinematics of deformation in northeast Iran. Morphotectonic investigations along both sides of the Binalud Mountains allowed us to characterize the structural and active faulting patterns along the Neyshabur and Mashhad fault systems on the southwest and northeast sides of the mountain range, respectively. We applied combined approaches of morphotectonic analyses based on satellite imageries (SPOT5 and Landsat ETM+), STRM and site-scale digital topographic data, and field surveys complemented with in situ-produced 10Be exposure dating to determine the kinematics and rate of active faulting. Three regional episodes of alluvial surface abandonments were dated at 5.3±1.1 kyr (Q1), 94±5 kyr (Q3), and 200±14 kyr (S3). The geomorphic reconstruction of both vertical and right-lateral fault offsets postdating these surface abandonment episodes yielded Quaternary fault slip rates on both sides of the Binalud Mountains. On the Neyshabur Fault System, thanks to geomorphic reconstructions of cumulative offsets recorded by Q3 fan surfaces, slip rates of 2.7±0.8 mm/yr and 2.4±0.2 mm/yr are estimated for right-lateral and reverse components of active faulting, respectively. Those indicate a total slip rate of 3.6±1.2 mm/yr for the late Quaternary deformation on the southwest flank of the Binalud Mountains. Reconstructing the cumulative right-lateral offset recorded by S3 surfaces, a middle-late Quaternary slip rate of 1.6±0.1 mm/yr is determined for the Mashhad Fault System. Altogether, our geomorphic observations reveal that, on both sides of the Binalud Mountains

  5. Closing the North American Carbon Budget: Continental Margin Fluxes Matter!

    NASA Astrophysics Data System (ADS)

    Najjar, R.; Benway, H. M.; Siedlecki, S. A.; Boyer, E. W.; Cai, W. J.; Coble, P. G.; Cross, J. N.; Friedrichs, M. A.; Goni, M. A.; Griffith, P. C.; Herrmann, M.; Lohrenz, S. E.; Mathis, J. T.; McKinley, G. A.; Pilskaln, C. H.; Smith, R. A.; Alin, S. R.

    2015-12-01

    Despite their relatively small surface area, continental margins are regions of intense carbon and nutrient processing, export and exchange, and thus have a significant impact on global biogeochemical cycles. In response to recommendations for regional synthesis and carbon budget estimation for North America put forth in the North American Continental Margins workshop report (Hales et al., 2008), the Ocean Carbon and Biogeochemistry (OCB) Program and North American Carbon Program (NACP) began coordinating a series of collaborative, interdisciplinary Coastal CARbon Synthesis (CCARS) research activities in five coastal regions of North America (Atlantic Coast, Pacific Coast, Gulf of Mexico, Arctic, Laurentian Great Lakes) to improve quantitative assessments of the North American carbon budget. CCARS workshops and collaborative research activities have resulted in the development of regional coastal carbon budgets based on recent literature- and model-based estimates of major carbon fluxes with estimated uncertainties. Numerous peer-reviewed papers and presentations by involved researchers have highlighted these findings and provided more in-depth analyses of processes underlying key carbon fluxes in continental margin systems. As a culminating outcome of these synthesis efforts, a comprehensive science plan highlights key knowledge gaps identified during this synthesis and provides explicit guidance on future research and observing priorities in continental margin systems to help inform future agency investments in continental margins research. This presentation will provide an overview of regional and flux-based (terrestrial inputs, biological transformations, sedimentary processes, atmospheric exchanges, lateral carbon transport) synthesis findings and key recommendations in the science plan, as well as a set of overarching priorities and recommendations on observations and modeling approaches for continental margin systems.

  6. Continental arc volcanism as the principal driver of icehouse-greenhouse variability.

    PubMed

    McKenzie, N Ryan; Horton, Brian K; Loomis, Shannon E; Stockli, Daniel F; Planavsky, Noah J; Lee, Cin-Ty A

    2016-04-22

    Variations in continental volcanic arc emissions have the potential to control atmospheric carbon dioxide (CO2) levels and climate change on multimillion-year time scales. Here we present a compilation of ~120,000 detrital zircon uranium-lead (U-Pb) ages from global sedimentary deposits as a proxy to track the spatial distribution of continental magmatic arc systems from the Cryogenian period to the present. These data demonstrate a direct relationship between global arc activity and major climate shifts: Widespread continental arcs correspond with prominent early Paleozoic and Mesozoic greenhouse climates, whereas reduced continental arc activity corresponds with icehouse climates of the Cryogenian, Late Ordovician, late Paleozoic, and Cenozoic. This persistent coupled behavior provides evidence that continental volcanic outgassing drove long-term shifts in atmospheric CO2 levels over the past ~720 million years. PMID:27102480

  7. Continental arc volcanism as the principal driver of icehouse-greenhouse variability

    NASA Astrophysics Data System (ADS)

    McKenzie, N. Ryan; Horton, Brian K.; Loomis, Shannon E.; Stockli, Daniel F.; Planavsky, Noah J.; Lee, Cin-Ty A.

    2016-04-01

    Variations in continental volcanic arc emissions have the potential to control atmospheric carbon dioxide (CO2) levels and climate change on multimillion-year time scales. Here we present a compilation of ~120,000 detrital zircon uranium-lead (U-Pb) ages from global sedimentary deposits as a proxy to track the spatial distribution of continental magmatic arc systems from the Cryogenian period to the present. These data demonstrate a direct relationship between global arc activity and major climate shifts: Widespread continental arcs correspond with prominent early Paleozoic and Mesozoic greenhouse climates, whereas reduced continental arc activity corresponds with icehouse climates of the Cryogenian, Late Ordovician, late Paleozoic, and Cenozoic. This persistent coupled behavior provides evidence that continental volcanic outgassing drove long-term shifts in atmospheric CO2 levels over the past ~720 million years.

  8. Molecular formula analysis of fragment ions by isotope-selective collision-induced dissociation tandem mass spectrometry of pharmacologically active compounds.

    PubMed

    Bianco, Giuliana; Buchicchio, Alessandro; Lelario, Filomena; Cataldi, Tommaso R I

    2014-12-01

    The purpose of this work is to explore the mass fragment characterization of commonly used drugs through a novel approach, which involves isotope-selective tandem mass spectrometry (MS/MS). Collision-induced dissociation (CID) was performed with a low-resolution linear ion trap mass spectrometer in positive electrospray ionization. Three pharmacologically active ingredients, i.e. omeprazole, meloxicam and brinzolamide, selected as model compounds in their own formulation, were investigated as a sodiated adduct [C17 H19 N3 O3 S + Na](+) (omeprazole) and as protonated adducts, [C14 H13 N3 O4 S2  + H](+) and [C12 H21 N3 O5 S3  + H](+) , meloxicam and brinzolamide, respectively. Selecting a narrow window of ±0.5 m/z units, precursor ion fragmentation by CID-MS/MS of isotopologues A + 0, A + 1 and A + 2 was found very useful to confirm the chemical formula of product ions, thus aiding the establishment of characteristic fragmentation pathways of all three examined compounds. The correctness of putative molecular formula of product ions was easily demonstrated by exploiting the isotope peak abundance ratios (i.e. IF+0 /IF+1 and IF+0 /IF+2 ) as simple constraints in low-resolution MS instrumentations. PMID:25476951

  9. Measurement of dijet production with a veto on additional central jet activity in pp collisions at sqrt {s} = 7 TeV using the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Alam, M. S.; Alam, M. A.; Albert, J.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Atoian, G.; Aubert, B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Austin, N.; Avolio, G.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Galtieri, A. Barbaro; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, D.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Battistoni, G.; Bauer, F.; Bawa, H. S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Harpaz, S. Behar; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ami, S. Ben; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benedict, B. H.; Benekos, N.; Benhammou, Y.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Kuutmann, E. Bergeaas; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernardet, K.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blazek, T.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bona, M.; Bondarenko, V. G.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boulahouache, C.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brown, H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Buanes, T.; Bucci, F.; Buchanan, J.; Buchanan, N. J.; Buchholz, P.; Buckingham, R. M.; Buckley, A. G.; Buda, S. I.; Budagov, I. A.; Budick, B.; Büscher, V.; Bugge, L.; Buira-Clark, D.; Bulekov, O.; Bunse, M.; Buran, T.; Burckhart, H.; Burdin, S.; Burgess, T.; Burke, S.; Busato, E.; Bussey, P.; Buszello, C. P.; Butin, F.; Butler, B.; Butler, J. M.; Buttar, C. M.; Butterworth, J. M.; Buttinger, W.; Byatt, T.; Cabrera Urbán, S.; Caforio, D.; Cakir, O.; Calafiura, P.; Calderini, G.; Calfayan, P.; Calkins, R.; Caloba, L. P.; Caloi, R.; Calvet, D.; Calvet, S.; Toro, R. Camacho; Camarri, P.; Cambiaghi, M.; Cameron, D.; Campana, S.; Campanelli, M.; Canale, V.; Canelli, F.; Canepa, A.; Cantero, J.; Capasso, L.; Capeans Garrido, M. D. M.; Caprini, I.; Caprini, M.; Capriotti, D.; Capua, M.; Caputo, R.; Caramarcu, C.; Cardarelli, R.; Carli, T.; Carlino, G.; Carminati, L.; Caron, B.; Caron, S.; Carrillo Montoya, G. D.; Carter, A. A.; Carter, J. R.; Carvalho, J.; Casadei, D.; Casado, M. P.; Cascella, M.; Caso, C.; Hernandez, A. M. Castaneda; Castaneda-Miranda, E.; Gimenez, V. Castillo; Castro, N. F.; Cataldi, G.; Cataneo, F.; Catinaccio, A.; Catmore, J. R.; Cattai, A.; Cattani, G.; Caughron, S.; Cauz, D.; Cavalleri, P.; Cavalli, D.; Cavalli-Sforza, M.; Cavasinni, V.; Ceradini, F.; Cerqueira, A. S.; Cerri, A.; Cerrito, L.; Cerutti, F.; Cetin, S. A.; Cevenini, F.; Chafaq, A.; Chakraborty, D.; Chan, K.; Chapleau, B.; Chapman, J. D.; Chapman, J. W.; Chareyre, E.; Charlton, D. G.; Chavda, V.; Barajas, C. A. Chavez; Cheatham, S.; Chekanov, S.; Chekulaev, S. V.; Chelkov, G. A.; Chelstowska, M. A.; Chen, C.; Chen, H.; Chen, S.; Chen, T.; Chen, X.; Cheng, S.; Cheplakov, A.; Chepurnov, V. F.; El Moursli, R. Cherkaoui; Chernyatin, V.; Cheu, E.; Cheung, S. L.; Chevalier, L.; Chiefari, G.; Chikovani, L.; Childers, J. T.; Chilingarov, A.; Chiodini, G.; Chizhov, M. 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G.; Tsukerman, I. I.; Tsulaia, V.; Tsung, J.-W.; Tsuno, S.; Tsybychev, D.; Tua, A.; Tuggle, J. M.; Turala, M.; Turecek, D.; Turk Cakir, I.; Turlay, E.; Turra, R.; Tuts, P. M.; Tykhonov, A.; Tylmad, M.; Tyndel, M.; Tyrvainen, H.; Tzanakos, G.; Uchida, K.; Ueda, I.; Ueno, R.; Ugland, M.; Uhlenbrock, M.; Uhrmacher, M.; Ukegawa, F.; Unal, G.; Underwood, D. G.; Undrus, A.; Unel, G.; Unno, Y.; Urbaniec, D.; Urkovsky, E.; Urrejola, P.; Usai, G.; Uslenghi, M.; Vacavant, L.; Vacek, V.; Vachon, B.; Vahsen, S.; Valenta, J.; Valente, P.; Valentinetti, S.; Valkar, S.; Valladolid Gallego, E.; Vallecorsa, S.; Valls Ferrer, J. A.; van der Graaf, H.; van der Kraaij, E.; Van Der Leeuw, R.; van der Poel, E.; van der Ster, D.; Van Eijk, B.; van Eldik, N.; van Gemmeren, P.; van Kesteren, Z.; van Vulpen, I.; Vandelli, W.; Vandoni, G.; Vaniachine, A.; Vankov, P.; Vannucci, F.; Varela Rodriguez, F.; Vari, R.; Varnes, E. W.; Varouchas, D.; Vartapetian, A.; Varvell, K. E.; Vassilakopoulos, V. I.; Vazeille, F.; Vegni, G.; Veillet, J. J.; Vellidis, C.; Veloso, F.; Veness, R.; Veneziano, S.; Ventura, A.; Ventura, D.; Venturi, M.; Venturi, N.; Vercesi, V.; Verducci, M.; Verkerke, W.; Vermeulen, J. C.; Vest, A.; Vetterli, M. C.; Vichou, I.; Vickey, T.; Viehhauser, G. H. A.; Viel, S.; Villa, M.; Villaplana Perez, M.; Vilucchi, E.; Vincter, M. G.; Vinek, E.; Vinogradov, V. B.; Virchaux, M.; Virzi, J.; Vitells, O.; Viti, M.; Vivarelli, I.; Vives Vaque, F.; Vlachos, S.; Vlasak, M.; Vlasov, N.; Vogel, A.; Vokac, P.; Volpi, G.; Volpi, M.; Volpini, G.; von der Schmitt, H.; von Loeben, J.; von Radziewski, H.; von Toerne, E.; Vorobel, V.; Vorobiev, A. P.; Vorwerk, V.; Vos, M.; Voss, R.; Voss, T. T.; Vossebeld, J. H.; Vranjes, N.; Vranjes Milosavljevic, M.; Vrba, V.; Vreeswijk, M.; Vu Anh, T.; Vuillermet, R.; Vukotic, I.; Wagner, W.; Wagner, P.; Wahlen, H.; Wakabayashi, J.; Walbersloh, J.; Walch, S.; Walder, J.; Walker, R.; Walkowiak, W.; Wall, R.; Waller, P.; Wang, C.; Wang, H.; Wang, H.; Wang, J.; Wang, J.; Wang, J. C.; Wang, R.; Wang, S. M.; Warburton, A.; Ward, C. P.; Warsinsky, M.; Watkins, P. M.; Watson, A. T.; Watson, M. F.; Watts, G.; Watts, S.; Waugh, A. T.; Waugh, B. M.; Weber, J.; Weber, M.; Weber, M. S.; Weber, P.; Weidberg, A. R.; Weigell, P.; Weingarten, J.; Weiser, C.; Wellenstein, H.; Wells, P. S.; Wen, M.; Wenaus, T.; Wendler, S.; Weng, Z.; Wengler, T.; Wenig, S.; Wermes, N.; Werner, M.; Werner, P.; Werth, M.; Wessels, M.; Weydert, C.; Whalen, K.; Wheeler-Ellis, S. J.; Whitaker, S. P.; White, A.; White, M. J.; White, S.; Whitehead, S. R.; Whiteson, D.; Whittington, D.; Wicek, F.; Wicke, D.; Wickens, F. J.; Wiedenmann, W.; Wielers, M.; Wienemann, P.; Wiglesworth, C.; Wiik, L. A. M.; Wijeratne, P. A.; Wildauer, A.; Wildt, M. A.; Wilhelm, I.; Wilkens, H. G.; Will, J. Z.; Williams, E.; Williams, H. H.; Willis, W.; Willocq, S.; Wilson, J. A.; Wilson, M. G.; Wilson, A.; Wingerter-Seez, I.; Winkelmann, S.; Winklmeier, F.; Wittgen, M.; Wolter, M. W.; Wolters, H.; Wong, W. C.; Wooden, G.; Wosiek, B. K.; Wotschack, J.; Woudstra, M. J.; Wraight, K.; Wright, C.; Wrona, B.; Wu, S. L.; Wu, X.; Wu, Y.; Wulf, E.; Wunstorf, R.; Wynne, B. M.; Xaplanteris, L.; Xella, S.; Xie, S.; Xie, Y.; Xu, C.; Xu, D.; Xu, G.; Yabsley, B.; Yacoob, S.; Yamada, M.; Yamaguchi, H.; Yamamoto, A.; Yamamoto, K.; Yamamoto, S.; Yamamura, T.; Yamanaka, T.; Yamaoka, J.; Yamazaki, T.; Yamazaki, Y.; Yan, Z.; Yang, H.; Yang, U. K.; Yang, Y.; Yang, Y.; Yang, Z.; Yanush, S.; Yao, W.-M.; Yao, Y.; Yasu, Y.; Ybeles Smit, G. V.; Ye, J.; Ye, S.; Yilmaz, M.; Yoosoofmiya, R.; Yorita, K.; Yoshida, R.; Young, C.; Youssef, S.; Yu, D.; Yu, J.; Yu, J.; Yuan, L.; Yurkewicz, A.; Zaets, V. G.; Zaidan, R.; Zaitsev, A. M.; Zajacova, Z.; Zalite, Yo. K.; Zanello, L.; Zarzhitsky, P.; Zaytsev, A.; Zeitnitz, C.; Zeller, M.; Zemla, A.; Zendler, C.; Zenin, O.; Ženiš, T.; Zenonos, Z.; Zenz, S.; Zerwas, D.; Zevi della Porta, G.; Zhan, Z.; Zhang, D.; Zhang, H.; Zhang, J.; Zhang, X.; Zhang, Z.; Zhao, L.; Zhao, T.; Zhao, Z.; Zhemchugov, A.; Zheng, S.; Zhong, J.; Zhou, B.; Zhou, N.; Zhou, Y.; Zhu, C. G.; Zhu, H.; Zhu, J.; Zhu, Y.; Zhuang, X.; Zhuravlov, V.; Zieminska, D.; Zimmermann, R.; Zimmermann, S.; Zimmermann, S.; Ziolkowski, M.; Zitoun, R.; Živković, L.; Zmouchko, V. V.; Zobernig, G.; Zoccoli, A.; Zolnierowski, Y.; Zsenei, A.; zur Nedden, M.; Zutshi, V.; Zwalinski, L.

    2011-09-01

    A measurement of jet activity in the rapidity interval bounded by a dijet system is presented. Events are vetoed if a jet with transverse momentum greater than 20 GeV is found between the two boundary jets. The fraction of dijet events that survive the jet veto is presented for boundary jets that are separated by up to six units of rapidity and with mean transverse momentum 50 < {bar{p}_{text{T}}} < 500 GeV. The mean multiplicity of jets above the veto scale in the rapidity interval bounded by the dijet system is also presented as an alternative method for quantifying perturbative QCD emission. The data are compared to a next-to-leading order plus parton shower prediction from the powheg-box, an all-order resummation using the hej calculation and the pythia, herwig++ and alpgen event generators. The measurement was performed using pp collisions at sqrt {s} = 7 TeV using data recorded by the ATLAS detector in 2010.

  10. Elastic Collisions and Gravity

    NASA Astrophysics Data System (ADS)

    Ball, Steven

    2009-04-01

    Elastic collisions are fascinating demonstrations of conservation principles. The mediating force must be conservative in an elastic collision. Truly elastic collisions take place only when the objects in collision do not touch, e.g. magnetic bumpers on low friction carts. This requires that we define a collision as a momentum transfer. Elastic collisions in 1-D can be solved in general and the implications are quite remarkable. For example, a heavy object moving initially towards a light object followed by an elastic collision results in a final velocity of the light object greater than either initial velocity. This is easily demonstrated with low friction carts. Gravitational elastic collisions involving a light spacecraft and an extremely massive body like a moon or planet can be approximated as 1-D collisions, such as the ``free return'' trajectory of Apollo 13 around the moon. The most fascinating gravitational collisions involve the gravitational slingshot effect used to boost spacecraft velocities. The maximum gravitational slingshot effect occurs when approaching a nearly 1-D collision, revealing that the spacecraft can be boosted to greater than twice the planet velocity, enabling the spacecraft to travel much further away from the Sun.

  11. Vortex-Surface Collisions^

    NASA Astrophysics Data System (ADS)

    Conlisk, A. T.

    1998-11-01

    The interaction of vortices with solid surfaces occurs in many different situations including, but not limited to tornadoes, propeller wakes, flows over swept wings and missile forebodies, turbomachinery flows, blade-vortex interactions and tip vortex-surface interactions on helicopters. Often, parts of a system must operate within such flows and thus encounter these vortices. In the present paper we discuss the nature of a particular subset of interactions called ``collisions''. A ``collision'' is characterized by the fact that the core of the vortex is permanently altered; usually the core is locally destroyed. The focus is on fully three-dimensional collisions although two-dimensional collisions are discussed as well. Examples of collisions in helicopter aerodynamics and turbomachinery flows are discussed and the dynamics of the vortex core during a collision process are illustrated for a 90^o collision. ^Supported by the US Army Research Office

  12. The development of topographic plateaus in an India-Asia-like collision zone using 3D numerical simulations

    NASA Astrophysics Data System (ADS)

    Pusok, Adina E.; Kaus, Boris; Popov, Anton

    2014-05-01

    The Himalayas and the adjacent Tibetan Plateau represent the most remarkable feature of the Earth's surface as the largest region of elevated topography and anomalously thick crust. Understanding the formation and evolution of the Himalayan-Tibetan region has become of high interest in the scientific community and different models have emerged over the last decades. They range from wholescale underthrusting of Indian lithospheric mantle under Tibet, distributed homogeneous shortening or the thin-sheet model, slip-line field model to the lower crustal flow model for the exhumation of the Himalayan units and lateral spreading of the Tibetan plateau. While some of these models have successfully illustrated some of the basic physics of continental collision, none can simultaneously represent active processes such as subduction, underthrusting, delamination, channel flow or extrusion, which are thought to be important during continental convergence, since these mechanisms require the lithosphere to interact with the underlying mantle. As such, 3D numerical models prove to be powerful tools in understanding the dynamics of coupled systems. However, because of yet recent developments and various complexities, the current 3D models simulating the dynamics of continental collision zones have relied on certain explicit assumptions, either focusing on crustal dynamics or slab-mantle dynamics. Here, we employ the parallel 3D code LaMEM (Lithosphere and Mantle Evolution Model), with a finite difference staggered grid solver, which is capable of simulating lithospheric deformation while simultaneously taking mantle flow and an internal free surface into account, which allows for the development of topography. We investigate the way deep processes affect continental tectonics at convergent margins, addressing the role continent subduction and collision have on the future of the subducting and overriding plates, and we discuss the implications these offer for the Asian tectonics

  13. Subduction of continental lithosphere in the Banda Sea region: Combining evidence from full waveform tomography and isotope ratios

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas; De Wit, Maarten; van Bergen, Manfred

    2010-09-01

    We provide new insight into the subduction of old continental lithosphere to depths of more than 100 km beneath the Banda arc, based on a spatial correlation of full waveform tomographic images of its lithosphere with He, Pb, Nd and Sr isotope signatures in its arc volcanics. The thickness of the subducted lithosphere of around 200 km coincides with the thickness of Precambrian lithosphere as inferred from surface wave tomography. While the deep subduction of continental material in continent-continent collisions is widely recognised, the analogue process in the arc-continent collision of the Banda region is currently unique. The integrated data suggest that the late Jurassic ocean lithosphere north of the North Australian craton was capable of entraining large volumes of continental lithosphere. The Banda arc example demonstrates that continental lithosphere in arc-continent collisions is not generally preserved, thus increasing the complexity of tectonic reconstructions. In the particular case of Timor, the tomographic images indicate that this island is not located directly above the northern margin of the North Australian craton, and that decoupled oceanic lithosphere must be located at a considerable distance north of Timor, possibly as far north as the northern margin of the volcanically extinct arc sector. The tomographic images combined with isotope data suggest that subduction of the continental lithosphere did not lead to the delamination of its complete crust. A plausible explanation involves delamination within the continental crust, separating upper from lower crustal units. This interpretation is consistent with the existence of a massive accretionary complex on Timor island, with evidence from Pb isotope analysis for lower-crust involvement in arc volcanism; and with the approximate gravitational stability of the subducted lithosphere as inferred from the tomographic images. The subduction of continental lithosphere including crustal material beneath

  14. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  15. Extension during continental convergence, with application to the Tibetan Plateau

    NASA Technical Reports Server (NTRS)

    England, Philip; Houseman, Gregory

    1989-01-01

    An explanation in terms of the thermal evolution of thickened continental lithosphere is offered to explain the transition, in the late Tertiary to Quaternary, from north-south compression to east-west extension in the strain rate field of the Tibetan Plateau. The lower part of the lithosphere consists of a thermal boundary layer which, when thickened by horizontal shortening, is colder and denser than its surroundings. Convective instability of the thickened thermal boundary layer and its replacement by hot asthenosphere would rapidly raise the surface elevation and gravitational potential energy of the overlying part of the lithosphere. The convective instability would happen in a time brief compared with the collision time scale but would only occur after there had already been substantial thickening of the lithosphere. The increase in surface height and of potential energy are sufficient for east-west extension to replace north-south compression as the dominant feature of the stress field.

  16. The Peruvian Continental Margin: Results from wide angle seismic Data

    NASA Astrophysics Data System (ADS)

    Krabbenhoeft, A.; Bialas, J.; Kopp, H.; Kukowski, N.; Huebscher, C.

    2003-04-01

    Within the scope of the GEOPECO (Geophysical Experiments at the Peruvian Continental Margin) project, seismic investigations along the Pacific margin of Peru were carried out using ocean bottom hydrophones (OBH) and seismometers (OBS) recording marine airgun shots. The structure and the P- wave velocity of the oblique subducting Nazca and overriding South-American Plates from 8°S to 15°S were determined by forward modeling and tomographic inversion of the wide-angle seismic data combined with the analysis of reflection seismic data. The region south of 12°S has been influenced by the southward migration of the aseismic Nazca Ridge the past 11 Ma. The oceanic Nazca Plate is divided by Mendana Fracture Zone (MFZ) which marks a transition zone of a different crustal age of approximately 28 Ma in the north to 38 Ma in the south at the Peruvian trench. North of MFZ the oceanic crust is influenced by Trujillo Trough trending N15E and the surrounding extensional stresses leading to a crustal thinning as can be seen in the northernmost refraction seismic model. The oceanic crust south of MFZ is overall homogeneous with a thin pelagic sedimentary layer and normal oceanic crustal layers. The P-wave velocity of the mantle is overall 7.9-8.1km/s. The Peruvian Continental Margin is characterized by the continental slope and several basins, Trujillo and Yaquina basin, Lima basin and Pisco basin, which are partly affected by the southward migration of the subducting Nazca Ridge. This caused uplift and subsidence along the margin leading to erosional tectonic features. The basins and continental basement could be mapped with forward modeling and tomographic inversion as well as the continental backstop on each profile. An accretionary prism is set up with a width of 20 to 30 km and 4 to 5 km thickness which does not further increase in size as revealed by the profiles recorded further north of Nazca Ridge. This and a taper of 14- 17 degrees at the collision zone indicates that

  17. 33 CFR 147.T17-0024 - Safety Zone; NOBLE DISCOVERER, Outer Continental Shelf Drillship, Chukchi and/or Beaufort Seas...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., Outer Continental Shelf Drillship, Chukchi and/or Beaufort Seas, Alaska. 147.T17-0024 Section 147.T17... CONTINENTAL SHELF ACTIVITIES SAFETY ZONES § 147.T17-0024 Safety Zone; NOBLE DISCOVERER, Outer Continental..., June 29, 2012, temporary § 147.T17-0024 was added, effective from July 1, 2012 to Dec. 1, 2012. 33...

  18. The Interpretation of Crustal Dynamics Data in Terms of Plate Interactions and Active Tectonics of the Anatolian Plate and Surrounding Regions in the Middle East

    NASA Technical Reports Server (NTRS)

    Toksoz, M. Nafi; Reilinger, Robert E.

    1990-01-01

    During the past 6 months, efforts were concentrated on the following areas: (1) Continued development of realistic, finite element modeling of plate interactions and associated deformation in the Eastern Mediterranean; (2) Neotectonic field investigations of seismic faulting along the active fault systems in Turkey with emphasis on identifying seismic gaps along the North Anatolian fault; and (3) Establishment of a GPS regional monitoring network in the zone of ongoing continental collision in eastern Turkey (supported in part by NSF).

  19. Crustal structure of the Southeast Georgia embayment-Carolina trough: Preliminary results of a composite seismic image of a continental suture ( ) and a volcanic passive margin

    SciTech Connect

    Austin, J.A. Jr.; Stoffa, P.L.; Phillips, J.D. ); Oh, Jinyong ); Sawyer, D.S. ); Purdy, G.M.; Reiter, E. ); Makris, J. )

    1990-10-01

    New deep-penetration multichannel seismic reflection data, combined with refraction results and magnetics modeling, support a hypothesis that the Carolina trough is a Mesozoic volcanic passive margin exhibiting a seaward-dipping wedge and associated underplating. The structure of Carolina platform continental crust is consistent with the late Paleozoic continental collision that produced the Appalachians, but imbrication has had no obvious effect on shallower structures produced by Mesozoic extension and volcanism. The origin of prominent magnetic anomalies crossing the Southeast Georgia embayment can be explained by processes attending Mesozoic separation of Africa and North America, and is not related to a Paleozoic continental suture, as previously postulated.

  20. Thermal models pertaining to continental growth

    NASA Technical Reports Server (NTRS)

    Morgan, Paul; Ashwal, Lew

    1988-01-01

    Thermal models are important to understanding continental growth as the genesis, stabilization, and possible recycling of continental crust are closely related to the tectonic processes of the earth which are driven primarily by heat. The thermal energy budget of the earth was slowly decreasing since core formation, and thus the energy driving the terrestrial tectonic engine was decreasing. This fundamental observation was used to develop a logic tree defining the options for continental growth throughout earth history.

  1. Continental aggregation, subduction initiation, and plume generation

    NASA Astrophysics Data System (ADS)

    Heron, P. J.; Lowman, J. P.

    2013-12-01

    Several processes unfold during the supercontinent cycle, more than one of which might result in an elevation in subcontinental mantle temperatures through the generation of mantle plumes. Paleogeographic plate reconstructions have indicated that sub-continental mantle upwellings appear below large continents that are extensively ringed by subduction zones. Moreover, several numerical simulations of supercontinent formation and dispersal attribute the genesis of sub-continental plumes to the generation of subduction zones on the edges of the supercontinent, rather than resulting from continental insulation. However, the role of the location of downwellings in producing a return-flow upwelling, and on increasing sub-continental mantle temperatures, is not fully understood. In this mantle convection study, we examine the evolution of mantle dynamics after supercontinent accretion over a subduction zone (analogous to the formation of Pangea) for a range of continental coverage. We present 2D and 3D Cartesian geometry mantle convection simulations, featuring geotherm- and pressure-dependent viscosity with thermally and mechanically distinct oceanic and continental plates. Through changing the size of the continent we are able to analyze the factors involved in the generation of mantle plumes in purely thermal convection. Furthermore, we change the upper and lower mantle viscosity to determine their relation to plume formation in vigorous mantle convection simulations. Elevated sub-continental temperatures are analyzed in relation to continental coverage to further understand the influence of continental tectonics on the thermal evolution of the mantle.

  2. Continental rifting: a planetary perspective

    SciTech Connect

    Muehlberger, W.R.

    1985-01-01

    The only inner planet that has abundant evidence of regional extension, and the consequent generation of rifts in the earth. The absence of plate motion on the other inner planets limits their rifts to localized bulges or subsidence areas. The rifting of oceanic lithosphere is seldom preserved in the geological record. Thus, such rifting must be inferred via plate tectonic interpretation: if there is rifting, then there must be subduction whose results are commonly well preserved. Modern continental rifts are found in many tectonic settings: continental breakup, extension transverse to collisional stresses, or wide regions of nearly uniform extension. Recognition of these settings in older rocks becomes more difficult the farther back in geologic time you travel. Rift basin fillings typically show rapid lateral and vertical facies and thickness changes, bimodal volcanism, and distinctive rift-drift sequences. Proterozoic rifts and aulacogens are well-documented in North America; ex. Keweenawan, western margin of Labrador fold belt, Belt-Uinta and the Wopmay-Athapuscow regions. Documented Archean rifts are rare. In Quebec, the truncated margin of the Minto craton bounded on the south by a 2.8 Ga greenstone belt implies an earlier rift event. The oldest proposed rift dated at 3.0 Ga contains the Pongola Supergroup in southeastern Africa. The presence of Archean dikes demonstrates a rigid crust and andesites as old as 3.5 Ga imply plate tectonics and thus, at least, oceanic rifting.

  3. Continental crust composition constrained by measurements of crustal Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Zandt, George; Ammon, Charles J.

    1995-03-01

    DECIPHERING the geological evolution of the Earth's continental crust requires knowledge of its bulk composition and global variability. The main uncertainties are associated with the composition of the lower crust. Seismic measurements probe the elastic properties of the crust at depth, from which composition can be inferred. Of particular note is Poisson's ratio,Σ ; this elastic parameter can be determined uniquely from the ratio of P- to S-wave seismic velocity, and provides a better diagnostic of crustal composition than either P- or S-wave velocity alone1. Previous attempts to measure Σ have been limited by difficulties in obtaining coincident P- and S-wave data sampling the entire crust2. Here we report 76 new estimates of crustal Σ spanning all of the continents except Antarctica. We find that, on average, Σ increases with the age of the crust. Our results strongly support the presence of a mafic lower crust beneath cratons, and suggest either a uniformitarian craton formation process involving delamination of the lower crust during continental collisions, followed by magmatic underplating, or a model in which crust formation processes have changed since the Precambrian era.

  4. The effect of thicker oceanic crust in the Archaean on the growth of continental crust through time

    NASA Technical Reports Server (NTRS)

    Wilks, M. E.

    1988-01-01

    Present crustal evolution models fail to account for the generation of the large volume of continental crust in the required time intervals. All Archaean plate tectonic models, whether invoking faster spreading rates, similar to today's spreading rates, or longer ridge lengths, essentially propose that continental crust has grown by island arc accretion due to the subduction of oceanic crust. The petrological differences that characterize the Archaean from later terrains result from the subduction of hotter oceanic crust into a hotter mantle. If the oceanic crust was appreciably thicker in the Archaean, as geothermal models would indicate, this thicker crust is surely going to have an effect on tectonic processes. A more valid approach is to compare the possible styles of convergence of thick oceanic crust with modern convergence zones. The best modern analog occurs where thick continental crust is colliding with thick continental crust. Oceanic crustal collision on the scale of the present-day Himalayan continental collision zone may have been a frequent occurrence in the Archaean, resulting in extensive partial melting of the hydrous underthrust oceanic crust to produce voluminous tonalite melts, leaving a depleted stabilized basic residuum. Present-day island arc accretion may not have been the dominant mechanism for the growth of the early Archaean crust.

  5. Magnetostratigraphic record of the early evolution of the southwestern Tian Shan foreland basin (Ulugqat area), interactions with Pamir indentation and India-Asia collision

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Dupont-Nivet, Guillaume; Jolivet, Marc; Guo, Zhaojie; Bougeois, Laurie; Bosboom, Roderic; Zhang, Ziya; Zhu, Bei; Heilbronn, Gloria

    2015-03-01

    The Tian Shan range is an inherited intracontinental structure reactivated by the far-field effects of the India-Asia collision. A growing body of thermochronology and magnetostratigraphy datasets shows that the range grew through several tectonic pulses since ~ 25 Ma, however the early Cenozoic history remains poorly constrained. The time-lag between the Eocene India-Asia collision and the Miocene onset of Tian Shan exhumation is particularly enigmatic. This peculiar period is potentially recorded along the southwestern Tian Shan piedmont. There, late Eocene marine deposits of the proto-Paratethys epicontinental sea transition to continental foreland basin sediments of unknown age were recently dated. We provide magnetostratigraphic dating of these continental sediments from the 1700-m-thick Mine section integrated with previously published detrital apatite fission track and U/Pb zircon ages. The most likely correlation to the geomagnetic polarity time scale indicates an age span from 20.8 to 13.3 Ma with a marked increase in accumulation rates at 19-18 Ma. This implies that the entire Oligocene period is missing between the last marine and first continental sediments, as suggested by previous southwestern Tian Shan results. This differs from the southwestern Tarim basin where Eocene marine deposits are continuously overlain by late Eocene-Oligocene continental sediments. This supports a simple evolution model of the western Tarim basin with Eocene-Oligocene foreland basin activation to the south related to northward thrusting of the Kunlun Shan, followed by early Miocene activation of northern foreland basin related to overthrusting of the south Tian Shan. Our data also support southward propagation of the Tian Shan piedmont from 20 to 18 Ma that may relate to motion on the Talas Fergana Fault. The coeval activation of a major right-lateral strike-slip system allowing indentation of the Pamir Salient into the Tarim basin, suggests far-field deformation from the

  6. Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia.

    PubMed

    van Hinsbergen, Douwe J J; Lippert, Peter C; Dupont-Nivet, Guillaume; McQuarrie, Nadine; Doubrovine, Pavel V; Spakman, Wim; Torsvik, Trond H

    2012-05-15

    Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India-Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. Since 52 Ma, the two plates have converged up to 3,600 ± 35 km, yet the upper crustal shortening documented from the geological record of Asia and the Himalaya is up to approximately 2,350-km less. Here we show that the discrepancy between the convergence and the shortening can be explained by subduction of highly extended continental and oceanic Indian lithosphere within the Himalaya between approximately 50 and 25 Ma. Paleomagnetic data show that this extended continental and oceanic "Greater India" promontory resulted from 2,675 ± 700 km of North-South extension between 120 and 70 Ma, accommodated between the Tibetan Himalaya and cratonic India. We suggest that the approximately 50 Ma "India"-Asia collision was a collision of a Tibetan-Himalayan microcontinent with Asia, followed by subduction of the largely oceanic Greater India Basin along a subduction zone at the location of the Greater Himalaya. The "hard" India-Asia collision with thicker and contiguous Indian continental lithosphere occurred around 25-20 Ma. This hard collision is coincident with far-field deformation in central Asia and rapid exhumation of Greater Himalaya crystalline rocks, and may be linked to intensification of the Asian monsoon system. This two-stage collision between India and Asia is also reflected in the deep mantle remnants of subduction imaged with seismic tomography. PMID:22547792

  7. Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia

    PubMed Central

    van Hinsbergen, Douwe J. J.; Lippert, Peter C.; Dupont-Nivet, Guillaume; McQuarrie, Nadine; Doubrovine, Pavel V.; Spakman, Wim; Torsvik, Trond H.

    2012-01-01

    Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India–Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. Since 52 Ma, the two plates have converged up to 3,600 ± 35 km, yet the upper crustal shortening documented from the geological record of Asia and the Himalaya is up to approximately 2,350-km less. Here we show that the discrepancy between the convergence and the shortening can be explained by subduction of highly extended continental and oceanic Indian lithosphere within the Himalaya between approximately 50 and 25 Ma. Paleomagnetic data show that this extended continental and oceanic “Greater India” promontory resulted from 2,675 ± 700 km of North–South extension between 120 and 70 Ma, accommodated between the Tibetan Himalaya and cratonic India. We suggest that the approximately 50 Ma “India”–Asia collision was a collision of a Tibetan-Himalayan microcontinent with Asia, followed by subduction of the largely oceanic Greater India Basin along a subduction zone at the location of the Greater Himalaya. The “hard” India–Asia collision with thicker and contiguous Indian continental lithosphere occurred around 25–20 Ma. This hard collision is coincident with far-field deformation in central Asia and rapid exhumation of Greater Himalaya crystalline rocks, and may be linked to intensification of the Asian monsoon system. This two-stage collision between India and Asia is also reflected in the deep mantle remnants of subduction imaged with seismic tomography. PMID:22547792

  8. Identification of epoxide functionalities in protonated monofunctional analytes by using ion/molecule reactions and collision-activated dissociation in different ion trap tandem mass spectrometers.

    PubMed

    Eismin, Ryan J; Fu, Mingkun; Yem, Sonoeun; Widjaja, Fanny; Kenttämaa, Hilkka I

    2012-01-01

    A mass spectrometric method has been delineated for the identification of the epoxide functionalities in unknown monofunctional analytes. This method utilizes gas-phase ion/molecule reactions of protonated analytes with neutral trimethyl borate (TMB) followed by collision-activated dissociation (CAD) in an ion trapping mass spectrometer (tested for a Fourier-transform ion cyclotron resonance and a linear quadrupole ion trap). The ion/molecule reaction involves proton transfer from the protonated analyte to TMB, followed by addition of the analyte to TMB and elimination of methanol. Based on literature, this reaction allows the general identification of oxygen-containing analytes. Vinyl and phenyl epoxides can be differentiated from other oxygen-containing analytes, including other epoxides, based on the loss of a second methanol molecule upon CAD of the addition/methanol elimination product. The only other analytes found to undergo this elimination are some amides but they also lose O = B-R (R = group bound to carbonyl), which allows their identification. On the other hand, other epoxides can be differentiated from vinyl and phenyl epoxides and from other monofunctional analytes based on the loss of (CH(3)O)(2)BOH or formation of protonated (CH(3)O)(2)BOH upon CAD of the addition/methanol elimination product. For propylene oxide and 2,3-dimethyloxirane, the (CH(3)O)(2)BOH fragment is more basic than the hydrocarbon fragment, and the diagnostic ion (CH(3)O)(2)BOH (2) (+) is formed. These reactions involve opening of the epoxide ring. The only other analytes found to undergo (CH(3)O)(2)BOH elimination are carboxylic acids, but they can be differentiated from the rest based on several published ion/molecule reaction methods. Similar results were obtained in the Fourier-transform ion cyclotron resonance and linear quadrupole ion trap mass spectrometer. PMID:22002227

  9. Identification of Epoxide Functionalities in Protonated Monofunctional Analytes by Using Ion/Molecule Reactions and Collision-Activated Dissociation in Different Ion Trap Tandem Mass Spectrometers

    NASA Astrophysics Data System (ADS)

    Eismin, Ryan J.; Fu, Mingkun; Yem, Sonoeun; Widjaja, Fanny; Kenttämaa, Hilkka I.

    2012-01-01

    A mass spectrometric method has been delineated for the identification of the epoxide functionalities in unknown monofunctional analytes. This method utilizes gas-phase ion/molecule reactions of protonated analytes with neutral trimethyl borate (TMB) followed by collision-activated dissociation (CAD) in an ion trapping mass spectrometer (tested for a Fourier-transform ion cyclotron resonance and a linear quadrupole ion trap). The ion/molecule reaction involves proton transfer from the protonated analyte to TMB, followed by addition of the analyte to TMB and elimination of methanol. Based on literature, this reaction allows the general identification of oxygen-containing analytes. Vinyl and phenyl epoxides can be differentiated from other oxygen-containing analytes, including other epoxides, based on the loss of a second methanol molecule upon CAD of the addition/methanol elimination product. The only other analytes found to undergo this elimination are some amides but they also lose O = B-R (R = group bound to carbonyl), which allows their identification. On the other hand, other epoxides can be differentiated from vinyl and phenyl epoxides and from other monofunctional analytes based on the loss of (CH3O)2BOH or formation of protonated (CH3O)2BOH upon CAD of the addition/methanol elimination product. For propylene oxide and 2,3-dimethyloxirane, the (CH3O)2BOH fragment is more basic than the hydrocarbon fragment, and the diagnostic ion (CH3O)2BOH{2/+} is formed. These reactions involve opening of the epoxide ring. The only other analytes found to undergo (CH3O)2BOH elimination are carboxylic acids, but they can be differentiated from the rest based on several published ion/molecule reaction methods. Similar results were obtained in the Fourier-transform ion cyclotron resonance and linear quadrupole ion trap mass spectrometer.

  10. Disequilibration by Planetary Collision

    NASA Astrophysics Data System (ADS)

    Asphaug, E. I.; Jutzi, M.

    2010-12-01

    Molten planets equilibrate gravitationally, chemically, and thermally. Large scale collisions (a.k.a. giant impacts, similar-sized collisions) can upset the apple cart by bringing core material, late in the game, into mixture with mantle products, and by shredding stratified planets into strands of mantle and clumps of core (c.g. Asphaug et al. Nature 2006). Atmophiles and volatiles come along for the ride, and can find themselves in disequilibrium mixtures not anticipated by one-dimensional models of planetary evolution, or by planet growth models in which planets stick, merge, and mix perfectly in the aftermath of a collision. We present very high resolution case studies of such collisions.

  11. Central collisions of heavy ions

    SciTech Connect

    Fung, Sun-yiu.

    1992-10-01

    This report describes the activities of the Heavy Ion Physics Group at the University of California, Riverside from October 1, 1991 to September 30, 1992. During this period, the program focused on particle production at AGS energies, and correlation studies at the Bevalac in nucleus-nucleus central collisions. As part of the PHENIX collaboration, contributions were made to the Preliminary Conceptual Design Report (pCDR), and work on a RHIC silicon microstrip detector R D project was performed.

  12. 26 CFR 1.638-1 - Continental Shelf areas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 7 2012-04-01 2012-04-01 false Continental Shelf areas. 1.638-1 Section 1.638-1...) INCOME TAXES (CONTINUED) Continental Shelf Areas § 1.638-1 Continental Shelf areas. (a) General rule. For.... The terms Continental Shelf of the United States and Continental Shelf of a possession of the...

  13. 26 CFR 1.638-1 - Continental Shelf areas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 7 2011-04-01 2009-04-01 true Continental Shelf areas. 1.638-1 Section 1.638-1...) INCOME TAXES (CONTINUED) Continental Shelf Areas § 1.638-1 Continental Shelf areas. (a) General rule. For.... The terms Continental Shelf of the United States and Continental Shelf of a possession of the...

  14. 26 CFR 1.638-1 - Continental Shelf areas.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 7 2013-04-01 2013-04-01 false Continental Shelf areas. 1.638-1 Section 1.638-1...) INCOME TAXES (CONTINUED) Continental Shelf Areas § 1.638-1 Continental Shelf areas. (a) General rule. For.... The terms Continental Shelf of the United States and Continental Shelf of a possession of the...

  15. 26 CFR 1.638-1 - Continental Shelf areas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 7 2010-04-01 2010-04-01 true Continental Shelf areas. 1.638-1 Section 1.638-1...) INCOME TAXES (CONTINUED) Continental Shelf Areas § 1.638-1 Continental Shelf areas. (a) General rule. For.... The terms Continental Shelf of the United States and Continental Shelf of a possession of the...

  16. 26 CFR 1.638-1 - Continental Shelf areas.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 7 2014-04-01 2013-04-01 true Continental Shelf areas. 1.638-1 Section 1.638-1...) INCOME TAXES (CONTINUED) Continental Shelf Areas § 1.638-1 Continental Shelf areas. (a) General rule. For.... The terms Continental Shelf of the United States and Continental Shelf of a possession of the...

  17. Petrogenesis of Cretaceous mafic intrusive rocks in the Fosdick Mountains, Marie Byrd Land, West Antarctica: melting of metasomatized sub-continental arc mantle along the active plate margin of Gondwana

    NASA Astrophysics Data System (ADS)

    Saito, S.; Brown, M.; Korhonen, F. J.; Mcfadden, R. R.; Siddoway, C. S.

    2013-12-01

    A diorite pluton and widely distributed mafic dykes occur in the Fosdick migmatite-granite complex, which is interpreted to represent middle-to-lower crustal rocks of the paleo-Pacific active continental margin of Gondwana. The mafic dykes exhibit a variety of relationships with host rocks in the field ranging from undeformed dykes with sharp contacts with host gneisses to dismembered dykes with comingled textures and numerous back-veins of leucosome intruded from host migmatitic gneisses suggestive of significant interaction with crustal rocks. U-Pb ages for magmatic zircon in these rocks yields Cretaceous crystallization ages ranging from ca. 113 Ma to ca. 98 Ma for the mafic dykes and ca. 100 Ma for the diorite pluton. These mafic intrusive rocks, which contain abundant hydrous minerals, are medium- to high-K-series calc-alkaline rocks with basic-intermediate compositions (47-59 wt % SiO2 for mafic dykes and 52-56 wt % SiO2 for the diorite pluton). They have trace element patterns characterized by LILE enrichments and negative Nb anomalies indicating an origin from a hydrous mantle source metasomatized by slab-derived components. The samples without evidence of interaction with crustal rocks, which are likely to better reflect the mantle source composition, have positive ɛSr(100Ma) values (+8.1 to +14.5) and negative to slightly positive ɛNd(100Ma) values (-1.6 to +2.5) consistent with derivation from an enriched mantle source. These samples may be divided into two groups either characterized by higher LILE/HFSE ratios, less radiogenic ɛSr(100Ma) values and more radiogenic ɛNd(100Ma) values, or characterized by relatively lower LILE/ HFSE ratios, more radiogenic ɛSr(100Ma) values and less radiogenic ɛNd(100Ma) values suggesting differences in the mantle source. The results of this study are consistent with melting of a variably metasomatized sub-arc mantle source during a transition from a wrench to a transtensional tectonic setting, but are inconsistent

  18. Continental margin sedimentation: from sediment transport to sequence stratigraphy

    USGS Publications Warehouse

    Nittrouer, Charles A., (Edited By); Austin, James A.; Field, Michael E.; Kravitz, Joseph H.; Syvitski, James P.M.; Wiberg, Patricia L.

    2007-01-01

    This volume on continental margin sedimentation brings together an expert editorial and contributor team to create a state-of-the-art resource. Taking a global perspective, the book spans a range of timescales and content, ranging from how oceans transport particles, to how thick rock sequences are formed on continental margins. - Summarizes and integrates our understanding of sedimentary processes and strata associated with fluvial dispersal systems on continental shelves and slopes - Explores timescales ranging from particle transport at one extreme, to deep burial at the other - Insights are presented for margins in general, and with focus on a tectonically active margin (northern California) and a passive margin (New Jersey), enabling detailed examination of the intricate relationships between a wide suite of sedimentary processes and their preserved stratigraphy - Includes observational studies which document the processes and strata found on particular margins, in addition to numerical models and laboratory experimentation, which provide a quantitative basis for extrapolation in time and space of insights about continental-margin sedimentation - Provides a research resource for scientists studying modern and ancient margins, and an educational text for advanced students in sedimentology and stratigraphy

  19. A Facies Model for Temperate Continental Glaciers.

    ERIC Educational Resources Information Center

    Ashley, Gail Mowry

    1987-01-01

    Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)

  20. How Continental Bank outsourced its "crown jewels.".

    PubMed

    Huber, R L

    1993-01-01

    No industry relies more on information than banking does, yet Continental, one of America's largest banks, outsources its information technology. Why? Because that's the best way to service the customers that form the core of the bank's business, says vice chairman Dick Huber. In the late 1970s and early 1980s, Continental participated heavily with Penn Square Bank in energy investments. When falling energy prices burst Penn Square's bubble in 1982, Continental was stuck with more than $1 billion in bad loans. Eight years later when Dick Huber came on board, Continental was working hard to restore its once solid reputation. Executives had made many tough decisions already, altering the bank's focus from retail to business banking and laying off thousands of employees. Yet management still needed to cut costs and improve services to stay afloat. Regulators, investors, and analysts were watching every step. Continental executives, eager to focus on the bank's core mission of serving business customers, decided to outsource one after another in-house service--from cafeteria services to information technology. While conventional wisdom holds that banks must retain complete internal control of IT, Continental bucked this argument when it entered into a ten-year, multimillion-dollar contract with Integrated Systems Solutions Corporation. Continental is already reaping benefits from outsourcing IT. Most important, Continental staffers today focus on their true core competencies: intimate knowledge of customers' needs and relationships with customers. PMID:10124146

  1. Elastic and Inelastic Collisions

    ERIC Educational Resources Information Center

    Gluck, Paul

    2010-01-01

    There have been two articles in this journal that described a pair of collision carts used to demonstrate vividly the difference between elastic and inelastic collisions. One cart had a series of washers that were mounted rigidly on a rigid wooden framework, the other had washers mounted on rubber bands stretched across a framework. The rigidly…

  2. Ball Collision Experiments

    ERIC Educational Resources Information Center

    Cross, R.

    2015-01-01

    Experiments are described on collisions between two billiard balls and between a bat and a ball. The experiments are designed to extend a student's understanding of collision events and could be used either as a classroom demonstration or for a student project.

  3. Morphology and shallow geological structure of the continental slope located between Manzanillo, Colima and Chamela, Jalisco, Mexico, using multibeam bathymetry and high resolution seismic reflection data

    NASA Astrophysics Data System (ADS)

    Castillo, M.; Bandy, W. L.; Mortera-Gutierrez, C. A.

    2013-05-01

    The west coast of Mexico presents a complex array of tectonic processes related with the subduction of the Rivera plate beneath the Jalisco Block/North American plate including seamount subduction and forearc slivering. To better understand these processes and related deformation, an analysis and integration of marine geophysical data was undertaken to map the morphology and shallow geologic structure of the continental slope located between Manzanillo, Colima and Chamela, Jalisco, Mexico (Longitude: 104 ° 20 'to 106 ° 0 Latitude: 18 ° 24 'to 19 ° 48'). These data include multibeam bathymetry and seafloor backscatter data (Kongsberg EM300 system) and high-resolution seismic reflection data (Kongsberg TOPAS system) collected during the MORTIC07 campaign aboard the oceanographic vessel "El Puma". 3D models of the bathymetry and acoustic backscatter strength were constructed along with maps of the major geological and structural features, such as landslides and active faults and folds. The analysis indicates that the continental slope in this area has undergone significant vertical and horizontal movements producing several large slump blocks, a prominent sedimentary filled basin, and a series of transpressional ridges suggestive of a recent collision and subduction of a seamount, or similar bathymetric features.

  4. Continental Growth and the Sedimentary Record

    NASA Astrophysics Data System (ADS)

    Dhuime, B.; Hawkesworth, C. J.; Robinson, R. A. J.; Cawood, P. A.

    2014-12-01

    Detrital sedimentary rocks provide average samples of the continental crust formed at different times and in different places. Some materials are more susceptible to erosion and/or to preservation bias than others, and one issue is to understand how the compositions of a range of source rocks are then recorded in the sediments. Here we considered two different approaches to model the growth of the continental crust: (i) The variation of Nd isotopes in continental shales with different deposition ages, which requires a correction of the bias induced by preferential erosion of younger rocks through an erosion parameter usually referred to as 'K'. The determination of K, and the extent to which it varies in different erosion systems, thus have fundamental implications for the models of continental growth based on radiogenic isotopes in continental sediments. (ii) The variations in U-Pb, Hf and O isotopes in detrital zircons, from 'modern' sediments sampled worldwide. In this approach, O isotopes are used to screen 'hybrid' Hf model ages (i.e. ages resulting from mixing processes of crustal material from different ages) from Hf model ages that represent actual crust formation ages. These two approaches independently suggest that the continental crust has been generated continuously, but with a marked decrease in the continental growth rate at ~3 Ga. The >4 Ga to ~3 Ga period is characterised by relatively high net rates of continental growth (~3.0 km3.a-1), which are similar to the rates at which new crust is generated, and destroyed, at the present time. Net growth rates are much lower since 3 Ga (~0.8 km3.a-1), which may be attributed to higher rates of destruction of continental crust. The inflexion in the continental growth curve at ~3 Ga indicates a change in the way the crust was generated and preserved. This change may be linked to onset of subduction-driven plate tectonics and discrete subduction zones.

  5. Ultrahigh-pressure metamorphism: tracing continental crust into the mantle

    NASA Astrophysics Data System (ADS)

    Chopin, Christian

    2003-07-01

    More and more evidence is being discovered in Phanerozoic collision belts of the burial of crustal rocks to previously unsuspected (and ever increasing) depths, presently on the order of 150-200 km, and of exhumation from such depths. This extends by almost one order of magnitude the depth classically ascribed to the metamorphic cycling of continental crust, and demonstrates its possible subduction. The pieces of evidence for this new, ultrahigh-pressure (UHP) metamorphism exclusively occur in the form of relics of high-pressure minerals that escaped back-transformation during decompression. The main UHP mineral indicators are the high-pressure polymorphs of silica and carbon, coesite and microdiamond, respectively; the latter often demonstrably precipitated from a metamorphic fluid and is completely unrelated to kimberlitic diamond or any shock event. Recent discoveries of pyroxene exsolutions in garnet and of coesite exsolutions in titanite suggest a precursor garnet or titanite containing six-fold coordinated silicon, therefore still higher pressures than implied by diamond stability, on the order of 6 GPa. The UHP rocks raise a formidable geological problem: that of the mechanisms responsible for their burial and, more pressingly, for their exhumation from the relevant depths. The petrological record indicates that large tracts of UHP rocks were buried to conditions of low T/ P ratio, consistent with a subduction-zone context. Decompression occurred in most instances under continuous cooling, implying continuous heat loss to the footwall and hangingwall of the rising body. This rise along the subduction channel - an obvious mechanical discontinuity and weak zone - may be driven by buoyancy up to mid-crustal levels as a result of the lesser density of the acidic crustal rocks (even if completely re-equilibrated at depth) after delamination from the lower crust, in a convergent setting. Chronological studies suggest that the rates involved are typical plate

  6. 75 FR 61512 - Outer Continental Shelf Official Protraction Diagrams

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Bureau of Ocean Energy Management, Regulation and Enforcement Outer Continental Shelf Official... Outer Continental Shelf Official Protraction Diagrams (OPDs) located within Atlantic Ocean areas, with... informational purposes only. Outer Continental Shelf Official Protraction Diagrams in the North Atlantic,...

  7. Role of submarine canyons in the US Atlantic Continental Slope and upper Continental rise development

    SciTech Connect

    McGregor, B.A.

    1984-04-01

    Three areas of the US Atlantic continental slope and rise (seaward of George Bank, Delaware Bay, and Pamlico Sound north of Cape Hatteras) have been studied using seismic reflection profiles and mid-range sidescan-sonar data. The continental slope in all three areas is dissected by numerous submarine canyons. The general sea floor gradient of the slope and the morphology of the rise, however, vary among the areas. Submarine canyons are dominant morphologic features on the slope and have an important function in sediment transport and distribution on the rise. In the study area north of Cape Hatteras, however, the low relief of the rise topography indicates that ocean currents flowing parallel to the margin may also affect sediment distribution on the rise. Morphology and sedimentation patterns suggest that differences in canyon ages exist both within each area and among the areas. Spatial and temporal variability of canyon activity is important in determining sediment sources for the construction of the rise. Although the US Atlantic slope and rise are relatively sediment-starved at present, mid-range sidescan data and submersible observations and samples suggest that periodic sediment transport events occur within the canyons.

  8. Deep observation and sampling of the earth's continental crust (DOSECC). Final report

    SciTech Connect

    Not Available

    1985-05-01

    The need to validate and refine concepts regarding the structure, properties, and dynamic processes of the earth's continental crust through the use of the drill was the subject of the workshop sponsored by DOSECC, Inc. and held April 29 through May 1, 1985 in Houston, Texas and attended by more than 145 scientists. Scientific objectives and targets for a program of research drilling as part of basic studies of the continental lithosphere were discussed, with over 30 scientific proposals presented. Individual drilling proposals were grouped under several themes; basement structures and deep continental basins, active fault zones, thermal regimes and fossil mineralized hydrothermal/magma systems.

  9. Enantioselective Collision-Activated Dissociation of Gas-Phase Tryptophan Induced by Chiral Recognition of Protonated uc(l)-Alanine Peptides

    NASA Astrophysics Data System (ADS)

    Fujihara, Akimasa; Matsuyama, Hiroki; Tajiri, Michiko; Wada, Yoshinao; Hayakawa, Shigeo

    2016-06-01

    Enantioselective dissociation in the gas phase is important for enantiomeric enrichment and chiral transmission processes in molecular clouds regarding the origin of homochirality in biomolecules. Enantioselective collision-activated dissociation (CAD) of tryptophan (Trp) and the chiral recognition ability of uc(l)-alanine peptides (uc(l)-Ala n ; n = 2-4) were examined using a linear ion trap mass spectrometer. CAD spectra of gas-phase heterochiral H+(uc(d)-Trp)(uc(l)-Ala n ) and homochiral H+(uc(l)-Trp)(uc(l)-Ala n ) noncovalent complexes were obtained as a function of the peptide size n. The H2O-elimination product was observed in CAD spectra of both heterochiral and homochiral complexes for n = 2 and 4, and in homochiral H+(uc(l)-Trp)(uc(l)-Ala3), indicating that the proton is attached to the uc(l)-alanine peptide, and H2O loss occurs from H+(uc(l)-Ala n ) in the noncovalent complexes. H2O loss did not occur in heterochiral H+(uc(d)-Trp)(uc(l)-Ala3), where NH3 loss and (H2O + CO) loss were the primary dissociation pathways. In heterochiral H+(uc(d)-Trp)(uc(l)-Ala3), the protonation site is the amino group of uc(d)-Trp, and NH3 loss and (H2O + CO) loss occur from H+(uc(d)-Trp). uc(l)-Ala peptides recognize uc(d)-Trp through protonation of the amino group for peptide size n = 3. NH3 loss and (H2O + CO) loss from H+(uc(d)-Trp) proceeds via enantioselective CAD in gas-phase heterochiral H+(uc(d)-Trp)(uc(l)-Ala3) at room temperature, whereas uc(l)-Trp dissociation was not observed in homochiral H+(uc(l)-Trp)(uc(l)-Ala3). These results suggest that enantioselective dissociation induced by chiral recognition of uc(l)-Ala peptides through protonation could play an important role in enantiomeric enrichment and chiral transmission processes of amino acids.

  10. Understanding continental margin biodiversity: a new imperative.

    PubMed

    Levin, Lisa A; Sibuet, Myriam

    2012-01-01

    Until recently, the deep continental margins (200-4,000 m) were perceived as monotonous mud slopes of limited ecological or environmental concern. Progress in seafloor mapping and direct observation now reveals unexpected heterogeneity, with a mosaic of habitats and ecosystems linked to geomorphological, geochemical, and hydrographic features that influence biotic diversity. Interactions among water masses, terrestrial inputs, sediment diagenesis, and tectonic activity create a multitude of ecological settings supporting distinct communities that populate canyons and seamounts, high-stress oxygen minimum zones, and methane seeps, as well as vast reefs of cold corals and sponges. This high regional biodiversity is fundamental to the production of valuable fisheries, energy, and mineral resources, and performs critical ecological services (nutrient cycling, carbon sequestration, nursery and habitat support). It is under significant threat from climate change and human resource extraction activities. Serious actions are required to preserve the functions and services provided by the deep-sea settings we are just now getting to know. PMID:22457970

  11. Continental volume and freeboard through geological time

    NASA Technical Reports Server (NTRS)

    Schubert, G.; Reymer, A. P. S.

    1985-01-01

    The consequences of approximately constant freeboard for continental growth are explored using a model that relates the volumes of isostatically compensated continents and oceans to the secular decline in terrestrial heat flow. It is found that a post-Archean increase in freeboard by 200 m requires continental growth of only 10 percent, while a decrease in freeboard by 200 m during this same period necessitates a crustal growth of 40 percent. Shrinkage of the continental crust since the end of the Archean can be ruled out. Changes of more than 10 percent in post-Archean crustal thickness are highly unlikely.

  12. The Electrical Resistivity Structure of the Eastern Anatolian Collision Zone, Northeastern Anatolia

    NASA Astrophysics Data System (ADS)

    Cengiz, Özlem; Tuǧrul Başokur, Ahmet; Tolak Çiftçi, Elif

    2016-04-01

    The Northeastern Anatolia is located at the intensely deformed Eastern Anatolian Collision Zone (EACZ), and its tectonic framework is characterized by the collision of the Arabian plate with Eurasian. Although extensive attention is given to understand the crustal and upper mantle processes at this convergent boundary, there is still an ongoing debate over the geodynamic processes of the region. In this study, we were specifically interested in the geoelectric properties and thus geodynamics of the crust beneath the EACZ. Magnetotelluric (MT) measurements were made on two profiles across the north of the EACZ in 1998 as part of a national project undertaken by the Turkish Petroleum Corporation (TPAO). MT data in the frequency range of 300-0.001 Hz were collected from 168 stations located along 78 km north to south and 47 km west to east profiles where direct convergence occurs between Arabian and Eurasian plates. Two and three-dimensional inversion algorithms were used to obtain resistivity models of the study area. According to these models, the upper crust consists of low resistivity sedimentary rocks (<30 Ωm) that are underlain by highly resistive (~500-1000 Ωm) crystalline basement rocks of the Eastern Anatolian Accretionary Complex and Pontides. While the upper and lower crustal resistivity at the northern part of the study area shows a layered structure, significant horizontal and vertical variations for the rest of the EACZ exists on resistivity models. The broad low resistivity zones (<50 Ωm) observed at mid and lower crustal levels throughout the EACZ. These fluid-rich regions along with high temperatures could indicate weak zones representing the locations of active deformation induced by continent-continent collision and correlate with volcanic centers in the region. The variation in the resistivity structure supports the southward subduction model with the resistive continental block and the deep conductive zones presumably corresponding to the

  13. Are continental “adakites” derived from thickened or foundered lower crust?

    NASA Astrophysics Data System (ADS)

    Ma, Qiang; Zheng, Jian-Ping; Xu, Yi-Gang; Griffin, William L.; Zhang, Rui-Sheng

    2015-06-01

    The geochemical signatures of "adakites" are usually attributed to high-pressure (≥ 50 km) partial melting of mafic rocks, and accordingly the occurrence of adakitic magmas in continental settings is frequently used as an indicator of a thickened or foundered lower crust at the time of magma emplacement. These premises are built on experiments and modeling using an MORB-like source, but the probable source of continental "adakites" (i.e., continental lower crust) is compositionally different from MORB. To elucidate the effect of source inheritance and pressure on resultant melts, geochemical analyses and trace-element modeling have been carried out on Jurassic adakitic rocks from the northern part of the North China Craton. The results show that these continental adakitic melts can be generated at depths less than 40 km, and their "adakitic" signature is most likely inherited from their source rocks. Such conclusions can be applied to the Mesozoic adakitic magmas from the interior of the North China Craton. Only the "adakites" from collisional orogens (i.e., Tibet, Dabie UHP belt) require crustal melting at depths greater than 50 km, consistent with collision-induced crustal thickening in these areas. This study therefore highlights the importance of source composition when defining the formation conditions of magmatic rocks in general, and in particular questions the common use of "adakites" as an indicator of specific geodynamic situations.

  14. Convective Removal of Continental Margin Lithosphere at the Edges of Subducting Oceanic Plates

    NASA Astrophysics Data System (ADS)

    Levander, A.; Bezada, M. J.; Palomeras, I.; Masy, J.; Humphreys, E.; Niu, F.

    2013-12-01

    Although oceanic lithosphere is continuously recycled to the deeper mantle by subduction, the rates and manner in which different types of continental lithospheric mantle are recycled is unclear. Cratonic mantle can be chemically reworked and essentially decratonized, although the frequency of decratonization is unclear. Lithospheric mantle under or adjacent to orogenic belts can be lost to the deeper mantle by convective downwellings and delamination phenomena. Here we describe how subduction related processes at the edges of oceanic plates adjacent to passive continental margins removes the mantle lithosphere from beneath the margin and from the continental interior. This appears to be a widespread means of recycling non-cratonic continental mantle. Lithospheric removal requires the edge of a subducting oceanic plate to be at a relatively high angle to an adjacent passive continental margin. From Rayleigh wave and body wave tomography, and receiver function images from the BOLIVAR and PICASSO experiments, we infer large-scale removal of continental margin lithospheric mantle from beneath 1) the northern South American plate margin due to Atlantic subduction, and 2) the Iberian and North African margins due to Alboran plate subduction. In both cases lithospheric mantle appears to have been removed several hundred kilometers inland from the subduction zones. This type of ';plate-edge' tectonics either accompanies or pre-conditions continental margins for orogenic activity by thinning and weakening the lithosphere. These processes show the importance of relatively small convective structures, i.e. small subducting plates, in formation of orogenic belts.

  15. Measures of activity-based pedestrian exposure to the risk of vehicle-pedestrian collisions: space-time path vs. potential path tree methods.

    PubMed

    Yao, Shenjun; Loo, Becky P Y; Lam, Winnie W Y

    2015-02-01

    Research on the extent to which pedestrians are exposed to road collision risk is important to the improvement of pedestrian safety. As precise geographical information is often difficult and costly to collect, this study proposes a potential path tree method derived from time geography concepts in measuring pedestrian exposure. With negative binomial regression (NBR) and geographically weighted Poisson regression (GWPR) models, the proposed probabilistic two-anchor-point potential path tree (PPT) approach (including the equal and weighted PPT methods) are compared with the deterministic space-time path (STP) method. The results indicate that both STP and PPT methods are useful tools in measuring pedestrian exposure. While the STP method can save much time, the PPT methods outperform the STP method in explaining the underlying vehicle-pedestrian collision pattern. Further research efforts are needed to investigate the influence of walking speed and route choice. PMID:25555021

  16. Continental origin of the Bibong eclogite, southwestern Gyeonggi massif, South Korea

    NASA Astrophysics Data System (ADS)

    Park, Seung-Ik; Kwon, Sanghoon; Kim, Sung Won; Yi, Keewook; Santosh, M.

    2014-12-01

    Eclogite is a high-pressure (HP) metamorphic rock that provides important information about the subduction of both continental and oceanic crusts. In this study we present SHRIMP zircon U-Pb isotopic data for a suite of the basement gneisses to investigate the origin of the Proterozoic Bibong eclogite in the Hongseong area, South Korea. Zircon grains from the basement felsic gneisses yielded Paleoproterozoic protolith ages ranging from ca. 2197 to 1880 Ma, and were intruded by syenite at ca. 750 Ma. A HP regional metamorphic event of Triassic age (ca. 255-227 Ma) is recorded in the zircon rims of the country rocks, which is also observed in the zircons from the eclogite. The contacts between the Bibong eclogite and its host rocks support an origin for the Proterozoic protoliths, indicating continental intrusions. The Hongseong area thus preserves evidence for the Triassic collision, indicating a tectonic linkage among the northeast Asian continents.

  17. Volatile components and continental material of planets

    NASA Technical Reports Server (NTRS)

    Florenskiy, K. P.; Nikolayeva, O. V.

    1986-01-01

    It is shown that the continental material of the terrestrial planets varies in composition from planet to planet according to the abundances and composition of true volatiles (H20, CO2, etc.) in the outer shells of the planets. The formation of these shells occurs very early in a planet's evolution when the role of endogenous processes is indistinct and continental materials are subject to melting and vaporizing in the absence of an atmosphere. As a result, the chemical properties of continental materials are related not only to fractionation processes but also to meltability and volatility. For planets retaining a certain quantity of true volatile components, the chemical transformation of continental material is characterized by a close interaction between impact melting vaporization and endogeneous geological processes.

  18. Modeling the dynamics of continental shelf carbon.

    PubMed

    Hofmann, Eileen E; Cahill, Bronwyn; Fennel, Katja; Friedrichs, Marjorie A M; Hyde, Kimberly; Lee, Cindy; Mannino, Antonio; Najjar, Raymond G; O'Reilly, John E; Wilkin, John; Xue, Jianhong

    2011-01-01

    Continental margin systems are important contributors to global nutrient and carbon budgets. Effort is needed to quantify this contribution and how it will be modified under changing patterns of climate and land use. Coupled models will be used to provide projections of future states of continental margin systems. Thus, it is appropriate to consider the limitations that impede the development of realistic models. Here, we provide an overview of the current state of modeling carbon cycling on continental margins as well as the processes and issues that provide the next challenges to such models. Our overview is done within the context of a coupled circulation-biogeochemical model developed for the northeastern North American continental shelf region. Particular choices of forcing and initial fields and process parameterizations are used to illustrate the consequences for simulated distributions, as revealed by comparisons to observations using quantitative statistical metrics. PMID:21329200

  19. Newton's Strange Collisions.

    ERIC Educational Resources Information Center

    Erlichson, Herman

    1995-01-01

    Discusses Newton's apparent oversight of the role of energy considerations in collisions between two spherical bodies related to the third corollary of his "Laws of Motion." Investigates several theories that provide solutions to the mysterious oversight. (LZ)

  20. Time rate collision matrix

    SciTech Connect

    Stoenescu, M.L.; Smith, T.M.

    1980-02-01

    The collision integral terms in Boltzmann equation are reformulated numerically leading to the substitution of the multiple integrals with a multiplicative matrix of the two colliding species velocity distribution functions which varies with the differential collision cross section. A matrix of lower rank may be constructed when one of the distribution functions is specified, in which case the matrix elements represent kinetic transition probabilities in the velocity space and the multiplication of the time rate collision matrix with the unknown velocity distribution function expresses the time rate of change of the distribution. The collision matrix may be used to describe the time evolution of systems in nonequilibrium conditions, to evaluate the rate of momentum and energy transfer between given species, or to generate validity criteria for linearized kinetic equations.

  1. Continental Construction and Crustal Growth of Central Asian Orogenic Belt in Mongolia

    NASA Astrophysics Data System (ADS)

    Schulmann, K.; Guy, A.; Lehmann, J.; Seltmann, R.; Lexa, O.

    2013-12-01

    The geophysical and geochemical data document crustal growth and continent construction processes responsible for episodic formation of Central Asian Orogenic Belt (CAOB) crust in Mongolia. Here, well-defined Cambrian suture rims the western borders of Proterozoic continental fragments in Mongolia and Russia (1200 to 700 Ma). This arcuate suture zone is defined by numerous ophiolites (800-560 Ma) originated by Early Cambrian obduction of young (Late Proterozoic) oceanic basins and magmatic arcs. The juvenile crust further south is built by gneisses a metasediments dated at 530-470 Ma interpreted as a Cambro-Ordovician accretionary prism intruded by juvenile Devono-Carboniferous Japan type magmatic arcs. The southerly mantle fragments covered by Silurian cherts, Devonian basaltic volcanics and late Devonian volcanoclastic sediments are interpreted as an oceanic crust of back arc and oceanic arc affinity. Following scenario is proposed: 1) Proterozoic basement blocks formed N-S trending zone documented by the shape of Early Cambrian suture, 2) Devono-Carboniferous magmatic arcs were emplaced during E-W shortening event along western margin of this zone leading to moderate crustal shortening, 3) the intra oceanic ophiolites were thrust over Devonian volcanoclastics during Late Carboniferous in the E-W direction. All that suggests that the early Devonian (Phillipiny sea type) back arc spreading was replaced by 50 to 80 My lasting E-W compressive regime during prolonged activity of north trending Mongol-Okhotsk Pacific type subduction zone. The change in tectonic movements from E-W to N-S is responsible for oroclinal bending of trail of Mongolian microcontinents and scissor-like closure of Mongol Okhotsk (Pacific ocean embayment) ocean. We conclude that both crustal growth and crustal construction are episodic in the CAOB. The former process occurred in two main episodes related to Pacific subduction, while the continental construction is a complex sequence of two peri

  2. Coordination: southeast continental shelf studies. Progress report

    SciTech Connect

    Menzel, D.W.

    1981-02-01

    The objectives are to identify important physical, chemical and biological processes which affect the transfer of materials on the southeast continental shelf, determine important parameters which govern observed temporal and spatial varibility on the continental shelf, determine the extent and modes of coupling between events at the shelf break and nearshore, and determine physical, chemical and biological exchange rates on the inner shelf. Progress in meeting these research objectives is presented. (ACR)

  3. Freshwater peat on the continental shelf

    USGS Publications Warehouse

    Emery, K.O.; Wigley, R.L.; Bartlett, A.S.; Rubin, M.; Barghoorn, E.S.

    1967-01-01

    Freshwater peats from the continental shelf off northeastern United States contain the same general pollen sequence as peats from ponds that are above sea level and that are of comparable radiocarbon ages. These peats indicate that during glacial times of low sea level terrestrial vegetation covered the region that is now the continental shelf in an unbroken extension from the adjacent land areas to the north and west.

  4. Freshwater peat on the continental shelf.

    PubMed

    Emery, K O; Wigley, R L; Bartlett, A S; Rubin, M; Barghoorn, E S

    1967-12-01

    Freshwater peats from the continental shelf off northeastern United States contain the same general pollen sequence as peats from ponds that are above sea level and that are of comparable radiocarbon ages. These peats indicate that during glacial times of low sea level terrestrial vegetation covered the region that is now the continental shelf in an unbroken extension from the adjacent land areas to the north and west. PMID:17801856

  5. Photon-photon collisions

    SciTech Connect

    Burke, D.L.

    1982-10-01

    Studies of photon-photon collisions are reviewed with particular emphasis on new results reported to this conference. These include results on light meson spectroscopy and deep inelastic e..gamma.. scattering. Considerable work has now been accumulated on resonance production by ..gamma gamma.. collisions. Preliminary high statistics studies of the photon structure function F/sub 2//sup ..gamma../(x,Q/sup 2/) are given and comments are made on the problems that remain to be solved.

  6. Preheating in bubble collisions

    SciTech Connect

    Zhang Jun; Piao Yunsong

    2010-08-15

    In a landscape with metastable minima, the bubbles will inevitably nucleate. We show that when the bubbles collide, due to the dramatic oscillation of the field at the collision region, the energy deposited in the bubble walls can be efficiently released by the explosive production of the particles. In this sense, the collision of bubbles is actually highly inelastic. The cosmological implications of this result are discussed.

  7. Canada basin: age and history of its continental margin

    SciTech Connect

    Sweeney, J.F.

    1985-02-01

    Presently available age controls suggest that the Canada basin formed during the Cretaceous Period between about 131 and 79 Ma. The opening process began with continental breakup that may have involved all parts of the North American polar margin at about the same time. The opening was completed by the formation of oceanic crust during the extended Cretaceous interval of normal geomagnetic polarity. Features characteristics of continental breakup, insofar as they are known, show systematic regional differences. From Brock to Axel Heiberg Island, continental breakup was associated with an extended (100 + Ma) stratigraphic hiatus and, northeastward from Ellef Ringnes Island, with extensive tholeiitic igneous activity. From Banks Island to northeastern Alaska, the breakup interval was abbreviated (20-30 Ma), and sparse igneous activity occurred. These differences can be produced by changes in the rate and/or amount of crustal stretching during margin formation and would imply relatively faster or more stretching northeast of Brock island. A continental margin of fixed age, exhibiting the indicated pattern of crustal stretching, could be produced along the trailing edge of a rotating block (Arctic Alaska terrane AA) with its pivot near the Mackenzie delta. When the rotation is restored, however, geological discrepancies are evident between Devonian and older rocks across the conjugate margins, suggesting an earlier history of drifting for the AA. Early Paleozoic correlations appear improved if the AA is placed, polar margin to polar margin, against northern Ellesmere Island and Greenland, where in the middle Paleozoic, it was sheared sinistrally along the Canadian margin to its pre-rotated position opposite Banks Island.

  8. Launch Collision Probability

    NASA Technical Reports Server (NTRS)

    Bollenbacher, Gary; Guptill, James D.

    1999-01-01

    This report analyzes the probability of a launch vehicle colliding with one of the nearly 10,000 tracked objects orbiting the Earth, given that an object on a near-collision course with the launch vehicle has been identified. Knowledge of the probability of collision throughout the launch window can be used to avoid launching at times when the probability of collision is unacceptably high. The analysis in this report assumes that the positions of the orbiting objects and the launch vehicle can be predicted as a function of time and therefore that any tracked object which comes close to the launch vehicle can be identified. The analysis further assumes that the position uncertainty of the launch vehicle and the approaching space object can be described with position covariance matrices. With these and some additional simplifying assumptions, a closed-form solution is developed using two approaches. The solution shows that the probability of collision is a function of position uncertainties, the size of the two potentially colliding objects, and the nominal separation distance at the point of closest approach. ne impact of the simplifying assumptions on the accuracy of the final result is assessed and the application of the results to the Cassini mission, launched in October 1997, is described. Other factors that affect the probability of collision are also discussed. Finally, the report offers alternative approaches that can be used to evaluate the probability of collision.

  9. A collision avoidance system for a spaceplane manipulator arm

    NASA Technical Reports Server (NTRS)

    Sciomachen, Anna; Magnani, Piergiovanni

    1989-01-01

    Part of the activity in the area of collision avoidance related to the Hermes spaceplane is reported. A collision avoidance software system which was defined, developed and implemented in this project is presented. It computes the intersection between the solids representing the arm, the payload, and the objects. It is feasible with respect to the resources available on board, considering its performance.

  10. The Continental Crust: A Geophysical Approach

    NASA Astrophysics Data System (ADS)

    Christensen, Nikolas I.

    Nearly 80 years ago, Yugoslavian seismologist Andrija Mohorovicic recognized, while studying a Balkan earthquake, that velocities of seismic waves increase abruptly at a few tens of kilometers depth , giving rise to the seismological definition of the crust. Since that discovery, many studies concerned with the nature of both the continental and oceanic crusts have appeared in the geophysical literature.Recently, interest in the continental crust has cascaded. This is largely because of an infusion of new data obtained from major reflection programs such as the Consortium for Continental Reflection Profiling (COCORP) and British Institutions Reflection Profiling Syndicate (BIRPS) and increased resolution of refraction studies. In addition, deep continental drilling programs are n ow in fashion. The Continental Crust: A Geophysical Approach is a summary of present knowledge of the continental crust. Meissner has succeeded in writing a book suited to many different readers, from the interested undergraduate to the professional. The book is well documented , with pertinent figures and a complete and up-to-date reference list.

  11. Geophysical study of the structure and processes of the continental convergence zones: Alpine-Himalayan Belt

    NASA Technical Reports Server (NTRS)

    Toksoez, M. N.

    1981-01-01

    The seismic wave velocity structure in the crust and upper mantle region beneath the Tibetan plateau was studied in detail. Also, a preliminary study of the uppermost mantle P wave velocity beneath Iran and Turkey was carried out, and the results are compared with those for the Tibetan plateau. These two studies compose the bulk of the efforts on the observational aspects of continental collision zones in addition to satellite derived data. On the theoretical aspects the thermal evolution of converging plate boundaries was explored using a finite difference scheme.

  12. Growth of the lower continental crust

    NASA Technical Reports Server (NTRS)

    Rudnick, Roberta L.

    1988-01-01

    One of the largest uncertainties in crustal composition and growth models is the nature of the lower continental crust. Specifically, by what processes is it formed and modified, and when is it formed, particularly in reference to the upper crust? The main reason for this lack of information is the scarcity of lower crustal rock samples. These are restricted to two types: rocks which outcrop in granulite facies terrains and granulite facies xenoliths which are transported to the earth's surface by young volcanics. The important conclusions arising from the xenolith studies are: the majority of mafic lower crustal xenoliths formed through cumulate process, resitic xenoliths are rare; and formation and metamorphism of the deep crust is intimately linked to igneous activity and/or orogeny which are manifest in one form or another at the earth's surface. Therefore, estimates of crustal growth based on surface exposures is representative, although the proportion of remobilized pre-existing crust may be significantly greater at the surface than in the deep crust.

  13. Dating the India-Eurasia collision through arc magmatic records

    NASA Astrophysics Data System (ADS)

    Bouilhol, Pierre; Jagoutz, Oliver; Hanchar, John M.; Dudas, Francis O.

    2013-03-01

    The Himalayan orogeny, a result of the collision of India and Eurasia, provides direct evidence of strain accommodation and large-scale rheological behavior of the continental lithosphere. Knowledge of the timing of the India-Eurasia collision is essential to understand the physical processes involved in collisional systems. Here we present a geochronological and multi-isotopic study on rocks from the upper crust of the Kohistan Paleo-Island Arc that formed in the equatorial part of the Neo-Tethys Ocean. In situ U-Pb geochronology and Hf isotopes in zircon, and whole-rock Nd and Sr isotopic data of plutonic rocks from the Kohistan-Ladakh Batholith, are used to construct a continuous record of the isotopic evolution of the source region of these granitoids that are related to both the subduction of the oceanic lithosphere and subsequent arc-continent collisions. We demonstrate that profound changes in the source region of these rocks correspond to collisional events. Our dataset constrains that the Kohistan-Ladakh Island Arc initially collided along the Indus suture zone with India at 50.2±1.5 Ma, an age generally attributed to the final India-Eurasia collision for the entire Himalayan belt. In the western Himalaya, the final collision between the assembled India/Arc and Eurasia however, occurred ∼10 Ma later at 40.4±1.3 Ma along the so-called Shyok suture zone. We present evidence indicating that a similar dual collision scenario can be extended to the east and conclude that a final India/Arc-Eurasia collision at ∼40 Ma integrates crucial aspects of the magmatic, tectonic, and sedimentary record of the whole Himalayan mountain belt.

  14. Petrogenesis of mafic magmatism in Arabia-Eurasia collision zone: valley filling flows in Armenia

    NASA Astrophysics Data System (ADS)

    Meliksetian, Khachatur; Neill, Iain; Allen, Mark; Navasardyan, Gevorg

    2015-04-01

    The Turkish- Armenian-Iranian orogenic plateau grew after the Middle Miocene following the initial Paleogene Arabia- Eurasia collision. It is widely accepted, that uplift of the plateau is related to break-off of the southern Neo-Tethys slab beneath the Bitlis-Zagros Suture at ~15-10 Ma, coupled with continued plate convergence and regional crustal shortening. Since this time there has also been a widespread mantle-derived collision magmatism over large parts of NW Iran, Eastern Anatolia and the Lesser Caucasus, potentially hundreds of kilometres from the site of southern Neo-Tethys slab break-off, >10 Myr after the proposed break-off event. Detailed wholer rock geochemistry and Sr-Nd-Pb-Hf isotope data are presented for ~2.5 Ma trachy-basalt to trachy-basaltic andesite lavas erupted in Armenia in the South Caucasus. These thick (up to 400 m) mafic flows generated several plateaux within the Lesser Caucasus: the Javakheti Plateau (S Georgia and NW Armenia), and the Lori and Kotayk Plateaux (Armenia). These basalts sequences also extend to the NE Kars-Erzurum Plateau in eastern Turkey. It is demonstrated that studied series formed by <5% melting of fertile subduction-modified spinel-facies lithospheric mantle, and very few display elemental or isotopic evidence for contamination by the 45-km thick Mesozoic-Paleogene arc crust or South Armenian Block continental crust. Recent magmatic activity in Armenia may not a direct consequence of southern Neo-Tethys slab break-off 300-450 km to the south of the country. It is possible that Late Miocene break-off of a second (northern Neo-Tethys) slab beneath the Pontide Arc allowed asthenospheric upwelling over a much wider area than was affected by southern Neo-Tethyan break-off. Whole-scale delamination of mantle lithosphere can be ruled out due to the modest degrees of partial melting, a lack of asthenospheric components and limited crustal interaction of the Armenian magmas. Small-scale sub-lithospheric convection may be

  15. Pb isotopes in the Sunda-Banda arc (Indonesia) as tracers of input from slab, sediment and continental crust

    NASA Astrophysics Data System (ADS)

    Elburg, M. A.; van Bergen, M. J.; Foden, J. D.

    2003-04-01

    Pb isotopic arrays in Quaternary volcanics from the Sunda-Banda arc have previously been interpreted as representing mixing between sub-arc mantle and subducted continental material. The mantle component in the non-collisional section of the arc appears to resemble Indian Ocean-type Mid Ocean Ridge basalt (I-MORB). In the eastern portion of the arc, where the Australian continent collides with the arc, the mantle component has been inferred to have Pb isotopic characteristics similar to Indian Ocean Island Basalt (I-OIB). Compilation of existing Pb and He isotope data on the active arc and combination with new Pb data on the inactive section shows that all volcanoes from the collisional section, independent of their depth to the Benioff zone, have high 208Pb/204Pb for their 207Pb/204Pb ratios, characteristic of I-OIB. However, there is no a-priori physical explanation why an OIB-type source would be tapped at the very moment that continental collision sets in. It is more likely that the Pb isotopic arrays in both the collisional and non-collisional section represent mixing of two subducted components. In the collisional section, this would be Australian upper and lower crust; in the non-collisional section, oceanic crust and entrained sediment. Within the non-collisional section, the Quaternary potassic volcanoes on the island of Sumbawa form a Pb isotopic array in a 208Pb/204Pb versus 207Pb/204Pb diagram that lies in between that of the lower-K non-collisional volcanics, and the samples from the collisional section. This contrasts with 2-4 Ma low-K volcanics from the island, that fall within the field for other low-K volcanoes. The sudden change to potassic volcanism with this particular Pb isotopic signature is thought to represent subduction of oceanic crust with more OIB-type characteristics, perhaps similar to material seen near Christmas Island. Samples from Romang, Wetar, Lirang and south Alor within the extinct section of the arc are characterised by

  16. Deglaciation and glacial erosion: A joint control on magma productivity by continental unloading

    NASA Astrophysics Data System (ADS)

    Sternai, Pietro; Caricchi, Luca; Castelltort, Sébastien; Champagnac, Jean-Daniel

    2016-02-01

    Glacial-interglacial cycles affect the processes through which water and rocks are redistributed across the Earth's surface, thereby linking the solid Earth and climate dynamics. Regional and global scale studies suggest that continental lithospheric unloading due to ice melting during the transition to interglacials leads to increased continental magmatic, volcanic, and degassing activity. Such a climatic forcing on the melting of the Earth's interior, however, has always been evaluated regardless of continental unloading by glacial erosion, albeit the density of rock exceeds that of ice by approximately 3 times. Here we present and discuss numerical results involving synthetic but realistic topographies, ice caps, and glacial erosion rates suggesting that erosion may be as important as deglaciation in affecting continental unloading. Our study represents an additional step toward a more general understanding of the links between a changing climate, glacial processes, and the melting of the solid Earth.

  17. Measurement of the underlying event activity in pp collisions at sqrt {s} = 0.9 and 7 TeV with the novel jet-area/median approach

    NASA Astrophysics Data System (ADS)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hammer, J.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Teischinger, F.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Cerny, K.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Maes, T.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Charaf, O.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hreus, T.; Léonard, A.; Marage, P. E.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Rios, A. A. Ocampo; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Vanelderen, L.; Verwilligen, P.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Caudron, A.; Ceard, L.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Perrini, L.; Pin, A.; Piotrzkowski, K.; Schul, N.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Martins, M. Correa; De Jesus Damiao, D.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Aldá, W. L.; Carvalho, W.; Custódio, A.; Da Costa, E. M.; De Oliveira Martins, C.; De Souza, S. Fonseca; Figueiredo, D. Matos; Mundim, L.; Nogima, H.; Oguri, V.; Da Silva, W. L. Prado; Santoro, A.; Amaral, S. M. Silva Do; Jorge, L. Soares; Sznajder, A.; Anjos, T. S.; Bernardes, C. A.; Dias, F. A.; Tomei, T. R. Fernandez Perez; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Karadzhinova, A.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, S.; Guo, Y.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Teng, H.; Wang, S.; Zhu, B.; Zou, W.; Avila, C.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Dzelalija, M.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Elgammal, S.; Kamel, A. Ellithi; Khalil, S.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Müntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Azzolini, V.; Eerola, P.; Fedi, G.; Voutilainen, M.; Czellar, S.; Härkönen, J.; Heikkinen, A.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Korpela, A.; Tuuva, T.; Sillou, D.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; de Monchenault, G. Hamel; Jarry, P.; Locci, E.; Malcles, J.; Millischer, L.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dobrzynski, L.; de Cassagnac, R. Granier; Haguenauer, M.; Miné, P.; Mironov, C.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. 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A.; Sonnenschein, L.; Steggemann, J.; Teyssier, D.; Weber, M.; Bontenackels, M.; Cherepanov, V.; Davids, M.; Flügge, G.; Geenen, H.; Geisler, M.; Ahmad, W. Haj; Hoehle, F.; Kargoll, B.; Kress, T.; Kuessel, Y.; Linn, A.; Nowack, A.; Perchalla, L.; Pooth, O.; Rennefeld, J.; Sauerland, P.; Stahl, A.; Martin, M. Aldaya; Behr, J.; Behrenhoff, W.; Behrens, U.; Bergholz, M.; Bethani, A.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Castro, E.; Costanza, F.; Dammann, D.; Eckerlin, G.; Eckstein, D.; Flucke, G.; Geiser, A.; Glushkov, I.; Gunnellini, P.; Habib, S.; Hauk, J.; Hellwig, G.; Jung, H.; Kasemann, M.; Katsas, P.; Kleinwort, C.; Kluge, H.; Knutsson, A.; Krämer, M.; Krücker, D.; Kuznetsova, E.; Lange, W.; Lohmann, W.; Lutz, B.; Mankel, R.; Marfin, I.; Marienfeld, M.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Olzem, J.; Perrey, H.; Petrukhin, A.; Pitzl, D.; Raspereza, A.; Cipriano, P. M. Ribeiro; Riedl, C.; Rosin, M.; Salfeld-Nebgen, J.; Schmidt, R.; Schoerner-Sadenius, T.; Sen, N.; Spiridonov, A.; Stein, M.; Walsh, R.; Wissing, C.; Autermann, C.; Blobel, V.; Bobrovskyi, S.; Draeger, J.; Enderle, H.; Erfle, J.; Gebbert, U.; Görner, M.; Hermanns, T.; Höing, R. S.; Kaschube, K.; Kaussen, G.; Kirschenmann, H.; Klanner, R.; Lange, J.; Mura, B.; Nowak, F.; Pietsch, N.; Rathjens, D.; Sander, C.; Schettler, H.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Schröder, M.; Schum, T.; Seidel, M.; Stadie, H.; Steinbrück, G.; Thomsen, J.; Barth, C.; Berger, J.; Böser, C.; Chwalek, T.; De Boer, W.; Descroix, A.; Dierlamm, A.; Feindt, M.; Guthoff, M.; Hackstein, C.; Hartmann, F.; Hauth, T.; Heinrich, M.; Held, H.; Hoffmann, K. H.; Honc, S.; Katkov, I.; Kernert, D.; Komaragiri, J. R.; Martschei, D.; Mueller, S.; Müller, Th.; Niegel, M.; Nürnberg, A.; Oberst, O.; Oehler, A.; Ott, J.; Peiffer, T.; Quast, G.; Rabbertz, K.; Ratnikov, F.; Ratnikova, N.; Riedel, S.; Röcker, S.; Saout, C.; Scheurer, A.; Schilling, F.-P.; Schmanau, M.; Schott, G.; Simonis, H. J.; Stober, F. M.; Troendle, D.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weiler, T.; Zeise, M.; Ziebarth, E. B.; Daskalakis, G.; Geralis, T.; Kesisoglou, S.; Kyriakis, A.; Loukas, D.; Manolakos, I.; Markou, A.; Markou, C.; Mavrommatis, C.; Ntomari, E.; Gouskos, L.; Mertzimekis, T. J.; Panagiotou, A.; Saoulidou, N.; Evangelou, I.; Foudas, C.; Kokkas, P.; Manthos, N.; Papadopoulos, I.; Patras, V.; Aranyi, A.; Bencze, G.; Boldizsar, L.; Hajdu, C.; Hidas, P.; Horvath, D.; Kapusi, A.; Krajczar, K.; Radics, B.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Beni, N.; Molnar, J.; Palinkas, J.; Szillasi, Z.; Karancsi, J.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Beri, S. 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S.; Colaleo, A.; Creanza, D.; De Filippis, N.; De Palma, M.; Fiore, L.; Iaselli, G.; Lusito, L.; Maggi, G.; Maggi, M.; Marangelli, B.; My, S.; Nuzzo, S.; Pacifico, N.; Pompili, A.; Pugliese, G.; Selvaggi, G.; Silvestris, L.; Singh, G.; Venditti, R.; Zito, G.; Abbiendi, G.; Benvenuti, A. C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Meneghelli, M.; Montanari, A.; Navarria, F. L.; Odorici, F.; Perrotta, A.; Primavera, F.; Rossi, A. M.; Rovelli, T.; Siroli, G.; Travaglini, R.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Frosali, S.; Gallo, E.; Gonzi, S.; Meschini, M.; Paoletti, S.; Sguazzoni, G.; Tropiano, A.; Benussi, L.; Bianco, S.; Colafranceschi, S.; Fabbri, F.; Piccolo, D.; Fabbricatore, P.; Musenich, R.; Benaglia, A.; De Guio, F.; Di Matteo, L.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Malvezzi, S.; Manzoni, R. A.; Martelli, A.; Massironi, A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pedrini, D.; Ragazzi, S.; Redaelli, N.; Sala, S.; de Fatis, T. Tabarelli; Buontempo, S.; Montoya, C. A. Carrillo; Cavallo, N.; De Cosa, A.; Dogangun, O.; Fabozzi, F.; Iorio, A. O. M.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Azzi, P.; Bacchetta, N.; Bellan, P.; Bisello, D.; Branca, A.; Checchia, P.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gozzelino, A.; Kanishchev, K.; Lacaprara, S.; Lazzizzera, I.; Margoni, M.; Meneguzzo, A. T.; Nespolo, M.; Pazzini, J.; Perrozzi, L.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Tosi, M.; Vanini, S.; Zotto, P.; Zucchetta, A.; Zumerle, G.; Gabusi, M.; Ratti, S. P.; Riccardi, C.; Torre, P.; Vitulo, P.; Bilei, G. M.; Caponeri, B.; Fanò, L.; Lariccia, P.; Lucaroni, A.; Mantovani, G.; Menichelli, M.; Nappi, A.; Romeo, F.; Saha, A.; Santocchia, A.; Taroni, S.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Broccolo, G.; Castaldi, R.; D'Agnolo, R. T.; Dell'Orso, R.; Fiori, F.; Foà, L.; Giassi, A.; Kraan, A.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Palmonari, F.; Rizzi, A.; Serban, A. T.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Del Re, D.; Diemoz, M.; Fanelli, C.; Grassi, M.; Longo, E.; Meridiani, P.; Micheli, F.; Nourbakhsh, S.; Organtini, G.; Pandolfi, F.; Paramatti, R.; Rahatlou, S.; Sigamani, M.; Soffi, L.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Biino, C.; Botta, C.; Cartiglia, N.; Castello, R.; Costa, M.; Demaria, N.; Graziano, A.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Musich, M.; Obertino, M. M.; Pastrone, N.; Pelliccioni, M.; Potenza, A.; Romero, A.; Ruspa, M.; Sacchi, R.; Sola, V.; Solano, A.; Staiano, A.; Pereira, A. Vilela; Belforte, S.; Cossutti, F.; Della Ricca, G.; Gobbo, B.; Marone, M.; Montanino, D.; Penzo, A.; Schizzi, A.; Heo, S. G.; Kim, T. Y.; Nam, S. K.; Chang, S.; Chung, J.; Kim, D. H.; Kim, G. N.; Kong, D. J.; Park, H.; Ro, S. R.; Son, D. C.; Kim, J. Y.; Kim, Zero J.; Song, S.; Jo, H. Y.; Choi, S.; Gyun, D.; Hong, B.; Jo, M.; Kim, H.; Kim, T. J.; Lee, K. S.; Moon, D. H.; Park, S. 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M.; Nirunpong, K.; Poll, A.; Senkin, S.; Smith, V. J.; Williams, T.; Basso, L.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Jackson, J.; Kennedy, B. W.; Olaiya, E.; Petyt, D.; RadburnSmith, B. C.; Shepherd-Themistocleous, C. H.; Tomalin, I. R.; Womersley, W. J.; Bainbridge, R.; Ball, G.; Beuselinck, R.; Buchmuller, O.; Colling, D.; Cripps, N.; Cutajar, M.; Dauncey, P.; Davies, G.; Della Negra, M.; Ferguson, W.; Fulcher, J.; Futyan, D.; Gilbert, A.; Bryer, A. Guneratne; Hall, G.; Hatherell, Z.; Hays, J.; Iles, G.; Jarvis, M.; Karapostoli, G.; Lyons, L.; Magnan, A.-M.; Marrouche, J.; Mathias, B.; Nandi, R.; Nash, J.; Nikitenko, A.; Papageorgiou, A.; Pesaresi, M.; Petridis, K.; Pioppi, M.; Raymond, D. M.; Rogerson, S.; Rompotis, N.; Rose, A.; Ryan, M. J.; Seez, C.; Sharp, P.; Sparrow, A.; Tapper, A.; Acosta, M. Vazquez; Virdee, T.; Wakefield, S.; Wardle, N.; Whyntie, T.; Barrett, M.; Chadwick, M.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Leggat, D.; Leslie, D.; Martin, W.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Hatakeyama, K.; Liu, H.; Scarborough, T.; Henderson, C.; Rumerio, P.; Avetisyan, A.; Bose, T.; Fantasia, C.; Heister, A.; St. John, J.; Lawson, P.; Lazic, D.; Rohlf, J.; Sperka, D.; Sulak, L.; Alimena, J.; Bhattacharya, S.; Cutts, D.; Ferapontov, A.; Heintz, U.; Jabeen, S.; Kukartsev, G.; Landsberg, G.; Luk, M.; Narain, M.; Nguyen, D.; Segala, M.; Sinthuprasith, T.; Speer, T.; Tsang, K. V.; Breedon, R.; Breto, G.; De La Barca Sanchez, M. Calderon; Chauhan, S.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Dolen, J.; Erbacher, R.; Gardner, M.; Houtz, R.; Ko, W.; Kopecky, A.; Lander, R.; Mall, O.; Miceli, T.; Nelson, R.; Pellett, D.; Rutherford, B.; Searle, M.; Smith, J.; Squires, M.; Tripathi, M.; Sierra, R. Vasquez; Andreev, V.; Cline, D.; Cousins, R.; Duris, J.; Erhan, S.; Everaerts, P.; Farrell, C.; Hauser, J.; Ignatenko, M.; Jarvis, C.; Plager, C.; Rakness, G.; Schlein, P.; Tucker, J.; Valuev, V.; Weber, M.; Babb, J.; Clare, R.; Dinardo, M. E.; Ellison, J.; Gary, J. W.; Giordano, F.; Hanson, G.; Jeng, G. Y.; Liu, H.; Long, O. R.; Luthra, A.; Nguyen, H.; Paramesvaran, S.; Sturdy, J.; Sumowidagdo, S.; Wilken, R.; Wimpenny, S.; Andrews, W.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; Evans, D.; Golf, F.; Holzner, A.; Kelley, R.; Lebourgeois, M.; Letts, J.; Macneill, I.; Mangano, B.; Muelmenstaedt, J.; Padhi, S.; Palmer, C.; Petrucciani, G.; Pieri, M.; Ranieri, R.; Sani, M.; Sharma, V.; Simon, S.; Sudano, E.; Tadel, M.; Tu, Y.; Vartak, A.; Wasserbaech, S.; Würthwein, F.; Yagil, A.; Yoo, J.; Barge, D.; Bellan, R.; Campagnari, C.; D'Alfonso, M.; Danielson, T.; Flowers, K.; Geffert, P.; Incandela, J.; Justus, C.; Kalavase, P.; Koay, S. A.; Kovalskyi, D.; Krutelyov, V.; Lowette, S.; Mccoll, N.; Pavlunin, V.; Rebassoo, F.; Ribnik, J.; Richman, J.; Rossin, R.; Stuart, D.; To, W.; West, C.; Apresyan, A.; Bornheim, A.; Chen, Y.; Di Marco, E.; Duarte, J.; Gataullin, M.; Ma, Y.; Mott, A.; Newman, H. B.; Rogan, C.; Timciuc, V.; Traczyk, P.; Veverka, J.; Wilkinson, R.; Yang, Y.; Zhu, R. Y.; Akgun, B.; Carroll, R.; Ferguson, T.; Iiyama, Y.; Jang, D. W.; Liu, Y. F.; Paulini, M.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Drell, B. R.; Edelmaier, C. J.; Ford, W. T.; Gaz, A.; Heyburn, B.; Lopez, E. Luiggi; Smith, J. G.; Stenson, K.; Ulmer, K. A.; Wagner, S. R.; Agostino, L.; Alexander, J.; Chatterjee, A.; Eggert, N.; Gibbons, L. K.; Heltsley, B.; Hopkins, W.; Khukhunaishvili, A.; Kreis, B.; Mirman, N.; Kaufman, G. Nicolas; Patterson, J. R.; Ryd, A.; Salvati, E.; Sun, W.; Teo, W. D.; Thom, J.; Thompson, J.; Vaughan, J.; Weng, Y.; Winstrom, L.; Wittich, P.; Winn, D.; Abdullin, S.; Albrow, M.; Anderson, J.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bloch, I.; Burkett, K.; Butler, J. N.; Chetluru, V.; Cheung, H. W. K.; Chlebana, F.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gao, Y.; Green, D.; Gutsche, O.; Hanlon, J.; Harris, R. M.; Hirschauer, J.; Hooberman, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Kilminster, B.; Klima, B.; Kunori, S.; Kwan, S.; Lincoln, D.; Lipton, R.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Maruyama, S.; Mason, D.; McBride, P.; Mishra, K.; Mrenna, S.; Musienko, Y.; Newman-Holmes, C.; O'Dell, V.; Prokofyev, O.; Sexton-Kennedy, E.; Sharma, S.; Spalding, W. J.; Spiegel, L.; Tan, P.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vidal, R.; Whitmore, J.; Wu, W.; Yang, F.; Yumiceva, F.; Yun, J. C.; Acosta, D.; Avery, P.; Bourilkov, D.; Chen, M.; Das, S.; De Gruttola, M.; Di Giovanni, G. P.; Dobur, D.; Drozdetskiy, A.; Field, R. D.; Fisher, M.; Fu, Y.; Furic, I. K.; Gartner, J.; Hugon, J.; Kim, B.; Konigsberg, J.; Korytov, A.; Kropivnitskaya, A.; Kypreos, T.; Low, J. F.; Matchev, K.; Milenovic, P.; Mitselmakher, G.; Muniz, L.; Remington, R.; Rinkevicius, A.; Sellers, P.; Skhirtladze, N.; Snowball, M.; Yelton, J.; Zakaria, M.; Gaultney, V.; Lebolo, L. M.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Adams, J. R.; Adams, T.; Askew, A.; Bochenek, J.; Chen, J.; Diamond, B.; Gleyzer, S. V.; Haas, J.; Hagopian, S.; Hagopian, V.; Jenkins, M.; Johnson, K. F.; Prosper, H.; Veeraraghavan, V.; Weinberg, M.; Baarmand, M. M.; Dorney, B.; Hohlmann, M.; Kalakhety, H.; Vodopiyanov, I.; Adams, M. R.; Anghel, I. M.; Apanasevich, L.; Bai, Y.; Bazterra, V. E.; Betts, R. R.; Callner, J.; Cavanaugh, R.; Dragoiu, C.; Evdokimov, O.; Garcia-Solis, E. J.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Khalatyan, S.; Lacroix, F.; Malek, M.; O'Brien, C.; Silkworth, C.; Strom, D.; Varelas, N.; Akgun, U.; Albayrak, E. A.; Bilki, B.; Chung, K.; Clarida, W.; Duru, F.; Griffiths, S.; Lae, C. K.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Newsom, C. R.; Norbeck, E.; Olson, J.; Onel, Y.; Ozok, F.; Sen, S.; Tiras, E.; Wetzel, J.; Yetkin, T.; Yi, K.; Barnett, B. A.; Blumenfeld, B.; Bolognesi, S.; Fehling, D.; Giurgiu, G.; Gritsan, A. V.; Guo, Z. J.; Hu, G.; Maksimovic, P.; Rappoccio, S.; Swartz, M.; Whitbeck, A.; Baringer, P.; Bean, A.; Benelli, G.; Grachov, O.; Kenny, R. P., Iii; Murray, M.; Noonan, D.; Radicci, V.; Sanders, S.; Stringer, R.; Tinti, G.; Wood, J. S.; Zhukova, V.; Barfuss, A. F.; Bolton, T.; Chakaberia, I.; Ivanov, A.; Khalil, S.; Makouski, M.; Maravin, Y.; Shrestha, S.; Svintradze, I.; Gronberg, J.; Lange, D.; Wright, D.; Baden, A.; Boutemeur, M.; Calvert, B.; Eno, S. C.; Gomez, J. A.; Hadley, N. J.; Kellogg, R. G.; Kirn, M.; Kolberg, T.; Lu, Y.; Marionneau, M.; Mignerey, A. C.; Pedro, K.; Peterman, A.; Rossato, K.; Skuja, A.; Temple, J.; Tonjes, M. B.; Tonwar, S. C.; Twedt, E.; Bauer, G.; Bendavid, J.; Busza, W.; Butz, E.; Cali, I. A.; Chan, M.; Dutta, V.; Gomez Ceballos, G.; Goncharov, M.; Hahn, K. A.; Kim, Y.; Klute, M.; Lee, Y.-J.; Li, W.; Luckey, P. D.; Ma, T.; Nahn, S.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Rudolph, M.; Stephans, G. S. F.; Stöckli, F.; Sumorok, K.; Sung, K.; Velicanu, D.; Wenger, E. A.; Wolf, R.; Wyslouch, B.; Xie, S.; Yang, M.; Yilmaz, Y.; Yoon, A. S.; Zanetti, M.; Cooper, S. I.; Cushman, P.; Dahmes, B.; De Benedetti, A.; Franzoni, G.; Gude, A.; Haupt, J.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Mans, J.; Pastika, N.; Rekovic, V.; Rusack, R.; Sasseville, M.; Singovsky, A.; Tambe, N.; Turkewitz, J.; Cremaldi, L. M.; Kroeger, R.; Perera, L.; Rahmat, R.; Sanders, D. A.; Avdeeva, E.; Bloom, K.; Bose, S.; Butt, J.; Claes, D. R.; Dominguez, A.; Eads, M.; Jindal, P.; Keller, J.; Kravchenko, I.; Lazo-Flores, J.; Malbouisson, H.; Malik, S.; Snow, G. R.; Baur, U.; Godshalk, A.; Iashvili, I.; Jain, S.; Kharchilava, A.; Kumar, A.; Shipkowski, S. P.; Smith, K.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Haley, J.; Trocino, D.; Wood, D.; Zhang, J.; Anastassov, A.; Kubik, A.; Mucia, N.; Odell, N.; Ofierzynski, R. A.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Velasco, M.; Won, S.; Antonelli, L.; Berry, D.; Brinkerhoff, A.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kolb, J.; Lannon, K.; Luo, W.; Lynch, S.; Marinelli, N.; Morse, D. M.; Pearson, T.; Ruchti, R.; Slaunwhite, J.; Valls, N.; Warchol, J.; Wayne, M.; Wolf, M.; Ziegler, J.; Bylsma, B.; Durkin, L. S.; Hart, A.; Hill, C.; Hughes, R.; Killewald, P.; Kotov, K.; Ling, T. Y.; Puigh, D.; Rodenburg, M.; Vuosalo, C.; Williams, G.; Winer, B. L.; Adam, N.; Berry, E.; Elmer, P.; Gerbaudo, D.; Halyo, V.; Hebda, P.; Hegeman, J.; Hunt, A.; Laird, E.; Lopes Pegna, D.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Piroué, P.; Quan, X.; Raval, A.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zuranski, A.; Acosta, J. G.; Brownson, E.; Huang, X. T.; Lopez, A.; Mendez, H.; Oliveros, S.; Vargas, J. E. Ramirez; Zatserklyaniy, A.; Alagoz, E.; Barnes, V. E.; Benedetti, D.; Bolla, G.; Bortoletto, D.; De Mattia, M.; Everett, A.; Hu, Z.; Jones, M.; Koybasi, O.; Kress, M.; Laasanen, A. T.; Leonardo, N.; Maroussov, V.; Merkel, P.; Miller, D. H.; Neumeister, N.; Shipsey, I.; Silvers, D.; Svyatkovskiy, A.; Marono, M. Vidal; Yoo, H. D.; Zablocki, J.; Zheng, Y.; Guragain, S.; Parashar, N.; Adair, A.; Boulahouache, C.; Cuplov, V.; Ecklund, K. M.; Geurts, F. J. M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Zabel, J.; Betchart, B.; Bodek, A.; Chung, Y. S.; Covarelli, R.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Garcia-Bellido, A.; Goldenzweig, P.; Gotra, Y.; Han, J.; Harel, A.; Korjenevski, S.; Miner, D. C.; Vishnevskiy, D.; Zielinski, M.; Bhatti, A.; Ciesielski, R.; Demortier, L.; Goulianos, K.; Lungu, G.; Malik, S.; Mesropian, C.; Arora, S.; Atramentov, O.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Hits, D.; Lath, A.; Panwalkar, S.; Park, M.; Patel, R.; Richards, A.; Robles, J.; Rose, K.; Salur, S.; Schnetzer, S.; Seitz, C.; Somalwar, S.; Stone, R.; Thomas, S.; Cerizza, G.; Hollingsworth, M.; Spanier, S.; Yang, Z. C.; York, A.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Khotilovich, V.; Montalvo, R.; Osipenkov, I.; Pakhotin, Y.; Perloff, A.; Roe, J.; Safonov, A.; Sakuma, T.; Sengupta, S.; Suarez, I.; Tatarinov, A.; Toback, D.; Akchurin, N.; Damgov, J.; Dudero, P. R.; Jeong, C.; Kovitanggoon, K.; Lee, S. W.; Libeiro, T.; Roh, Y.; Volobouev, I.; Appelt, E.; Engh, D.; Florez, C.; Greene, S.; Gurrola, A.; Johns, W.; Kurt, P.; Maguire, C.; Melo, A.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Arenton, M. W.; Balazs, M.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Lin, C.; Neu, C.; Wood, J.; Yohay, R.; Gollapinni, S.; Harr, R.; Karchin, P. E.; Don, C. Kottachchi Kankanamge; Lamichhane, P.; Sakharov, A.; Anderson, M.; Bachtis, M.; Belknap, D.; Borrello, L.; Carlsmith, D.; Cepeda, M.; Dasu, S.; Gray, L.; Grogg, K. S.; Grothe, M.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Klukas, J.; Lanaro, A.; Lazaridis, C.; Leonard, J.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Pierro, G. A.; Ross, I.; Savin, A.; Smith, W. H.; Swanson, J.

    2012-08-01

    The first measurement of the charged component of the underlying event using the novel "jet-area/median" approach is presented for proton-proton collisions at centre-of-mass energies of 0.9 and 7 TeV. The data were recorded in 2010 with the CMS experiment at the LHC. A new observable, sensitive to soft particle production, is introduced and investigated inclusively and as a function of the event scale defined by the transverse momentum of the leading jet. Various phenomenological models are compared to data, with and without corrections for detector effects. None of the examined models describe the data satisfactorily.

  18. Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins

    NASA Astrophysics Data System (ADS)

    Levin, Lisa A.; Liu, Kon-Kee; Emeis, Kay-Christian; Breitburg, Denise L.; Cloern, James; Deutsch, Curtis; Giani, Michele; Goffart, Anne; Hofmann, Eileen E.; Lachkar, Zouhair; Limburg, Karin; Liu, Su-Mei; Montes, Enrique; Naqvi, Wajih; Ragueneau, Olivier; Rabouille, Christophe; Sarkar, Santosh Kumar; Swaney, Dennis P.; Wassman, Paul; Wishner, Karen F.

    2015-01-01

    The oceans' continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO2-induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins, (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO2-induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services. These include primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins.

  19. Comparative biogeochemistry-ecosystem-human interactions on dynamic continental margins

    USGS Publications Warehouse

    Levin, Lisa A.; Liu, Kon-Kee; Emeis, Kay-Christian; Breitburg, Denise L.; Cloern, James; Deutsch, Curtis; Giani, Michele; Goffart, Anne; Hofmann, Eileen E.; Lachkar, Zouhair; Limburg, Karin; Liu, Su-Mei; Montes, Enrique; Naqvi, Wajih; Ragueneau, Olivier; Rabouille, Christophe; Sarkar, Santosh Kumar; Swaney, Dennis P.; Wassman, Paul; Wishner, Karen F.

    2014-01-01

    The ocean’s continental margins face strong and rapid change, forced by a combination of direct human activity, anthropogenic CO2-induced climate change, and natural variability. Stimulated by discussions in Goa, India at the IMBER IMBIZO III, we (1) provide an overview of the drivers of biogeochemical variation and change on margins, (2) compare temporal trends in hydrographic and biogeochemical data across different margins (3) review ecosystem responses to these changes, (4) highlight the importance of margin time series for detecting and attributing change and (5) examine societal responses to changing margin biogeochemistry and ecosystems. We synthesize information over a wide range of margin settings in order to identify the commonalities and distinctions among continental margin ecosystems. Key drivers of biogeochemical variation include long-term climate cycles, CO2-induced warming, acidification, and deoxygenation, as well as sea level rise, eutrophication, hydrologic and water cycle alteration, changing land use, fishing, and species invasion. Ecosystem responses are complex and impact major margin services including primary production, fisheries production, nutrient cycling, shoreline protection, chemical buffering, and biodiversity. Despite regional differences, the societal consequences of these changes are unarguably large and mandate coherent actions to reduce, mitigate and adapt to multiple stressors on continental margins.

  20. The impact of salt tectonics on supra-salt (Lago Mare?) deposits and on the structural evolution of the Cyprus-Eratosthenes collision zone

    NASA Astrophysics Data System (ADS)

    Reiche, Sönke; Hübscher, Christian; Ehrhardt, Axel

    2015-04-01

    Averagely 1.5 km thick Messinian evaporites laterally continue from the Levant Basin, easternmost Mediterranean Sea, into the collision zone between Cyprus and Eratosthenes Seamount where incipient continent-continent-collision is believed to occur. In this study, the impact of Messinian evaporites on the structural evolution of the collision zone is investigated for the first time based on a comprehensive set of seismic reflection profiles. Results show that the collision zone may be subdivided into an eastern and a western domain. In the eastern part, bordered by Eratosthenes Seamount and the Hecataeus Rise, compressionally thickened autochthonous salt is observed. Sub- and supra-salt deposits within this area appear to be in the stage of active accretion. Further west, between Cyprus and Eratosthenes Seamount strongly deformed allochthonous salt has evidently started to advance across sediments of post-Messinian age. In this domain, previously active sediment accretion at the Cyprus margin has now become inactive and shortening is largely accommodated at the leading edge of the allochthonous salt sheet. Such observations bear important implications for the structural interrelation between salt tectonics and the evolution of a young collision zone. On top of highly deformed mobile Messinian evaporites, up to 700 m thick late Messinian supra-salt deposits are mapped within the western part of the Cyprus - Eratosthenes collision zone. Their uppermost 200 m were drilled in the course of ODP Leg 160 (Site 968) and interpreted as Lago Mare sediments, deposited during the final stage of the Messinian Salinity Crisis (Robertson, 1998). These sediments occupy small sub-basins flanked by salt diapirs, indicating a salt-tectonic control on late Messinian sediment deposition. Distribution of these sediments may have further been controlled by sea-level, inferred from rapid eastward thinning and pinchout of Messinian supra-salt deposits towards the Levant Basin

  1. Ion Collision, Theory

    SciTech Connect

    Shukla, Anil K.

    2013-09-11

    The outcome of a collision between an ion and neutral species depends on the chemical and physical properties of the two reactants, their relative velocities, and the impact parameter of their trajectories. These include elastic and inelastic scattering of the colliding particles, charge transfer (including dissociative charge transfer), atom abstraction, complex formation and dissociation of the colliding ion. Each of these reactions may be characterized in terms of their energy-dependent rate coefficients, cross sections and reaction kinetics. A theoretical framework that emphasizes simple models and classical mechanics is presented for these processes. Collision processes are addressed in two categories of low-energy and high-energy collisions. Experiments under thermal or quasi-thermal conditions–swarms, drift tubes, chemical ionization and ion cyclotron resonance are strongly influenced by long-range forces and often involve collisions in which atom exchange and extensive energy exchange are common characteristics. High-energy collisions are typically impulsive, involve short-range intermolecular forces and are direct, fast processes.

  2. Petrofabrics and Water Contents of Peridotites from the Western Gneiss Region (Norway): Implications for Fabric Transition of Olivine in Continental Subduction Zones

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Xia, Q.; O'Reilly, S.; Griffin, W. L.; Beyer, E.

    2010-12-01

    significantly affect the fabric development of peridotites during the continental collision. Combined with field observations in the WGR and recent deformation experiments on olivine, we propose that the B- and C-type fabrics of olivine were formed during the subduction of the Baltic plate in fluid-limited conditions. The combination of UHP and low temperature plays a more important role than water to promote [001] slip in continental subduction zones. The spatial distribution of olivine fabrics in the WGR could be related with the increasing pressure from south to north, i.e., the HP to UHP metamorphism transition. It is probable that in continental subduction zones, the B- and C-type fabrics will predominate over the A-type fabric with increasing depths of the subducting lithospheric mantle, and the C-type fabric is more easily to activated at pressure higher than 4 GPa on low geothermal gradients. Therefore the olivine C-type fabric may be a marker of ultradeep subduction.

  3. Permafrost warming and vegetation changes in continental Antarctica

    NASA Astrophysics Data System (ADS)

    Guglielmin, Mauro; Dalle Fratte, Michele; Cannone, Nicoletta

    2014-04-01

    Continental Antarctica represents the last pristine environment on Earth and is one of the most suitable contexts to analyze the relations between climate, active layer and vegetation. In 2000 we started long-term monitoring of the climate, permafrost, active layer and vegetation in Victoria Land, continental Antarctica. Our data confirm the stability of mean annual and summer air temperature, of snow cover, and an increasing trend of summer incoming short wave radiation. The active layer thickness is increasing at a rate of 0.3 cm y-1. The active layer is characterized by large annual and spatial differences. The latter are due to scarce vegetation, a patchy and very thin organic layer and large spatial differences in snow accumulation. The active layer thickening, probably due to the increase of incoming short wave radiation, produced a general decrease of the ground water content due to the better drainage of the ground. The resultant drying may be responsible for the decline of mosses in xeric sites, while it provided better conditions for mosses in hydric sites, following the species-specific water requirements. An increase of lichen vegetation was observed where the climate drying occurred. This evidence emphasizes that the Antarctic continent is experiencing changes that are in total contrast to the changes reported from maritime Antarctica.

  4. The basins on the Argentine continental margin

    SciTech Connect

    Urien, C.M.

    1996-08-01

    After the stabilization of the central Gondwana Craton, orogenic belts were accreted, as a result of convergence events and an extensive passive margin developed in southwestern Gondwana. Thermal subsidence in Parana, Karoo-Ventania basins and the Late Paleozoic-Early Mesozoic rifts, were modified by the Gondwana breakup and the South Atlantic opening. Early Paleozoic marine transgressions deposited the Table Mountain Group in Ventania. In southwestern Patagonia foreland clastics were deposited. Magmatic arcs and marine units indicate a tectonic trough was formed, alternating with continental sequences, over Late Paleozoic metamorphics and intrusives, resulting from plastered terrains along the Gondwana margin. In Patagonia, Permo-Carboniferous continental and glacio marine clastics infill the basins, while in Ventania, paralic sequences, grade from neritic to continental to the northeast, extending beneath the continental margin. The Triassic-Jurassic rift basins progressed onto regional widespread acid lavas and were infilled by lagoonal organic-rich sequences. Early drift phase built basins transverse to the margin, with fluvio-lacustrine sequences: Salado, Colorado, Valdes-Rawson, San Julian and North Malvinas intracratonic basins, which underwent transtensional faulting. Post-Oxfordian to Neocomian brackish sequences, onlapped the conjugate basins during the margin`s drift, with petroleum systems, as in Austral and Malvinas. In the Valanginian, basic extrusions commenced to form on the continental border, heralding the oceanic phase. Due to thermal subsidence, offlaping sediments prograded onto the remaining half-grabens. Several petroleum systems, proven and hypothetical, are identified in this region.

  5. Collision of cosmic superstrings

    SciTech Connect

    Copeland, E. J.; Firouzjahi, H.; Kibble, T. W. B.; Steer, D. A.

    2008-03-15

    We study the formation of three-string junctions between (p,q)-cosmic superstrings, and collisions between such strings and show that kinematic constraints analogous to those found previously for collisions of Nambu-Goto strings apply here too, with suitable modifications to take account of the additional requirements of flux conservation. We examine in detail several examples involving collisions between strings with low values of p and q, and also examine the rates of growth or shrinkage of strings at a junction. Finally, we briefly discuss the formation of junctions for strings in a warped space, specifically with a Klebanov-Strassler throat, and show that similar constraints still apply with changes to the parameters taking account of the warping and the background flux.

  6. Microscope collision protection apparatus

    DOEpatents

    DeNure, Charles R.

    2001-10-23

    A microscope collision protection apparatus for a remote control microscope which protects the optical and associated components from damage in the event of an uncontrolled collision with a specimen, regardless of the specimen size or shape. In a preferred embodiment, the apparatus includes a counterbalanced slide for mounting the microscope's optical components. This slide replaces the rigid mounts on conventional upright microscopes with a precision ball bearing slide. As the specimen contacts an optical component, the contacting force will move the slide and the optical components mounted thereon. This movement will protect the optical and associated components from damage as the movement causes a limit switch to be actuated, thereby stopping all motors responsible for the collision.

  7. Event activity dependence of Y(nS) production in $$\\sqrt{s_{NN}}$$=5.02 TeV pPb and $$\\sqrt{s}$$=2.76 TeV pp collisions

    DOE PAGESBeta

    Chatrchyan, Serguei

    2014-04-15

    The production of Y(1S), Y(2S), and Y(3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 nb–1 (pPb) and 5.4 pb–1 (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval (yCM) < 1.93 in the nucleon-nucleon centre-of-mass frame. Their production is studied as a function of two measures of event activity, namely the charged-particle multiplicity measured in the pseudorapidity interval |η| < 2.4, and the sum ofmore » transverse energy deposited at forward pseudorapidity, 4.0 < |η|< 5.2. The Y cross sections normalized by their event activity integrated values, Y(nS)/, are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, Y(nS)/Y(1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. Lastly, the event activity integrated double ratios, [Y(nS)/Y(1S)]pPb / [Y(nS)/Y(1S)]pp, are also measured and found to be 0.83 +/- 0.05 (stat.) +/- 0.05 (syst.) and 0.71 +/- 0.08 (stat.) +/- 0.09 (syst.) for Y(2S) and Y(3S), respectively.« less

  8. Event activity dependence of Y(nS) production in $\\sqrt{s_{NN}}$=5.02 TeV pPb and $\\sqrt{s}$=2.76 TeV pp collisions

    SciTech Connect

    Chatrchyan, Serguei

    2014-04-15

    The production of Y(1S), Y(2S), and Y(3S) is investigated in pPb and pp collisions at centre-of-mass energies per nucleon pair of 5.02 TeV and 2.76 TeV, respectively. The datasets correspond to integrated luminosities of about 31 nb–1 (pPb) and 5.4 pb–1 (pp), collected in 2013 by the CMS experiment at the LHC. Upsilons that decay into muons are reconstructed within the rapidity interval (yCM) < 1.93 in the nucleon-nucleon centre-of-mass frame. Their production is studied as a function of two measures of event activity, namely the charged-particle multiplicity measured in the pseudorapidity interval |η| < 2.4, and the sum of transverse energy deposited at forward pseudorapidity, 4.0 < |η|< 5.2. The Y cross sections normalized by their event activity integrated values, Y(nS)/, are found to rise with both measures of the event activity in pp and pPb. In both collision systems, the ratios of the excited to the ground state cross sections, Y(nS)/Y(1S), are found to decrease with the charged-particle multiplicity, while as a function of the transverse energy the variation is less pronounced. Lastly, the event activity integrated double ratios, [Y(nS)/Y(1S)]pPb / [Y(nS)/Y(1S)]pp, are also measured and found to be 0.83 +/- 0.05 (stat.) +/- 0.05 (syst.) and 0.71 +/- 0.08 (stat.) +/- 0.09 (syst.) for Y(2S) and Y(3S), respectively.

  9. Illustrations of the importance of mass wasting in the evolution of continental margins

    SciTech Connect

    Pratson, L.; Ryan, W. ); Twichell, D. )

    1990-05-01

    Side-looking sonar imagery and swath bathymetry from a variety of contemporary continental slopes all display erosional scars and debris aprons, illustrating the importance of mass wasting in the evolution of continental margins. The continental slopes examined include slopes fed directly from the fronts of ice sheets, slopes adjacent to continental shelves that were the sites of glacial outwash, slopes supplied exclusively by fluvial drainage, slopes at carbonate platforms, and slopes on accretionary prisms. Examples are drawn from the Atlantic Ocean, the Gulf of Mexico, and the Mediterranean Sea in both passive and active continental margin settings. The sonar imagery and bathymetry used in this study indicate that continental slopes in different tectonic and climatic environments show similar forms of mass wasting. However, in some cases the dominant mode of erosion and/or the overall degree of mass wasting appears to be distinct to particular sedimentary environments. Timing of both recent and older exhumed erosional surfaces identified in the imagery and in seismic reflection profiles is obtained by ground truth observations using submersibles, towed camera sleds, drilling, and coring. These observations suggest that eustatic fluctuations common to all the margins examined do not explain the range in magnitude and areal density of the observed mass wasting. More localized factors such as lithology, diagenesis, pore fluid conditions, sediment supply rates, and seismic ground motion appear to have a major influence in the evolution of erosional scars and their corresponding unconformities.

  10. Constraints on continental accretion from sedimentation

    NASA Technical Reports Server (NTRS)

    Abbott, Dallas

    1988-01-01

    Heat loss in the ancient Earth was discussed assuming that classical sea floor spreading was the only mechanism. This may be expressed as faster spreading or longer total ridge length. These have important implications as to the size and number of cratonic plates in the distant past, the degree to which they are flooded, the kinds of sediments and volcanics that would be expected, and the amount of recycling of continental material taking place. The higher proportion of marine sedimentary rocks and oceanic volcanics in the Archean, and the relative paucity of evaporites and continental volcanics may in part be due to smaller cratonic blocks. A model was developed of the percentage of continental flooding which utilizes round continents and a constant width of the zone of flooding. This model produces a reasonable good fit to the percentage of flooding on the present day continents.

  11. New observations of the active deformation along the oblique collision/subduction boundary zone between the North American and Caribbean plates (northern Hispaniola offshore margin)

    NASA Astrophysics Data System (ADS)

    Carbó-Gorosabel, Andrés; Granja Bruña, José Luis; Rodríguez Zurrunero, Álvaro; Gómez de la Peña, Laura; Muñoz-Martín, Alfonso; Gómez Ballesteros, María; Gorosabel Araus, José Miguel; Espinosa, Salvador; Pazos, Anatonio; Catalán, Manuel; Yamil Rodríguez Asilis, Hector; Nuñez, José Luis; Muñoz, Santiago; ten Brink, Uri S.; Quijano, Jesús; Llanes Estrada, Pilar; Martín Dávila, José; Druet, María

    2015-04-01

    The Caribbean plate is moving relative to the North American plate at a rate of 20.0 ± 0.4 mm/y towards 074° ± 1°. This eastward motion has been taking place during most of the Cenozoic developing a 250 km-wide band of deformation, in which microplate and block tectonics take place. The eastward motion of the Hispaniola block is being impeded relative to the motion of the Caribbean plate's interior due to the collision with the Bahamas banks. This collision has resulted in the development of the Northern Hispaniola deformed belt along the northern Hispaniola offshore margin. A series of large (M6.2-M8.1) thrust earthquakes from 1943-1953, and two significant events in 1994 (M5.6) and 2003 (M6.4) occurred close to the city of Puerto Plata have been attributed to oblique collision/subduction of the North America plate and Bahamas banks beneath the northern Hispaniola. 300 km of 2D multi-channel seismic (MCS) reflection data and approximately 15000 km2 of high-resolution, systematic swath bathymetry data were recorded in the northern Hispaniola offshore margin as part of a larger survey carried out in November-December of 2013 aboard the Spanish R/V Sarmiento de Gamboa. MCS profiles were collected shooting a GI gun array (GGUN-II®) of 1750 ci. every 37.5 m and the signal recorded in a 3000 m-long streamer with 240 channels (Sentinel Sercel®). Differential GPS navigated high-resolution bathymetry data were collected using the hull-mounted Hydrosweep ATLAS DS echo-sounder system. Using new high-resolution multibeam bathymetry and MCS data, combined with previous 2D seismic data, we have studied the along- and across-strike variations of the geomorphology and shallower structure of the northern Hispaniola offshore margin. Here we present preliminary results focused on the identification and characterization of recent tectonic features in the region and provide well-defined targets to carry out future studies for seismic and tsunamigenic hazard assessment.

  12. Late-Archean continental emergence: consequences for the rise of atmospheric oxygen

    NASA Astrophysics Data System (ADS)

    Flament, N. E.; Coltice, N.; Rey, P. F.

    2008-12-01

    The balance between the secular cooling of the Earth's mantle and the growth of the continental crust implies changes in the isostatic equilibrium between continents and oceans, in the oceanic bathymetry, and in the area of emerged continental crust. The evolution of the latter is of fundamental importance to the geochemical coupling between the continental crust, the atmosphere and the oceans. The area of emerged land can be estimated from models that depend on mantle temperature, continental area and continental hypsometry. In the Archean, the mantle was probably 150-200°C hotter than present and the continental area could have increased from 20% of present at ~~3.5Ga to 80% of present by ~~2.5Ga. Using these values, and comparing different thermal evolution models for the Earth, we calculate that the area of emerged continental crust would be reduced to 1-12% of the Earth's area during the Archean (compared to 27.5% for present-day Earth). As for the continental hypsometry, a greater radiogenic crustal heat production and a greater mantle heat flow would have reduced the strength of the continental lithosphere in the Archean, thus limiting the crustal thickening due to mountain building processes and the maximum elevation in the Earth's topography [Rey and Coltice, Geology 36, 635-638 (2008)]. Taking this into account, we show that the continents were mostly flooded until the end of the Archean and that less than 3% of the Earth's area (which is roughly the superficy of South America) consisted of emerged continental crust by ~~2.5~Ga. These results are consistent with widespread Archean submarine continental flood basalts, and with the emergence of a sialic geochemical reservoir recorded from ~~2.5~Ga in (a) the composition of shales, (b) the isotopic ratio 87Sr/86Sr of marine carbonates and (c) the δ18O signature of igneous zircons. The progressive emergence of the continents as shown by our models from the late

  13. Gas hydrates of outer continental margins

    SciTech Connect

    Kvenvolden, K.A. )

    1990-05-01

    Gas hydrates are crystalline substances in which a rigid framework of water molecules traps molecules of gas, mainly methane. Gas-hydrate deposits are common in continental margin sediment in all major oceans at water depths greater than about 300 m. Thirty-three localities with evidence for gas-hydrate occurrence have been described worldwide. The presence of these gas hydrates has been inferred mainly from anomalous lacoustic reflectors seen on marine seismic records. Naturally occurring marine gas hydrates have been sampled and analyzed at about tensites in several regions including continental slope and rise sediment of the eastern Pacific Ocean and the Gulf of Mexico. Except for some Gulf of Mexico gas hydrate occurrences, the analyzed gas hydrates are composed almost exclusively of microbial methane. Evidence for the microbial origin of methane in gas hydrates includes (1) the inverse relation between methane occurence and sulfate concentration in the sediment, (2) the subparallel depth trends in carbon isotopic compositions of methane and bicarbonate in the interstitial water, and (3) the general range of {sup 13}C depletion ({delta}{sub PDB}{sup 13}C = {minus}90 to {minus}60 {per thousand}) in the methane. Analyses of gas hydrates from the Peruvian outer continental margin in particular illustrate this evidence for microbially generated methane. The total amount of methane in gas hydrates of continental margins is not known, but estimates of about 10{sup 16} m{sup 3} seem reasonable. Although this amount of methane is large, it is not yet clear whether methane hydrates of outer continental margins will ever be a significant energy resource; however, these gas hydrates will probably constitute a drilling hazard when outer continental margins are explored in the future.

  14. Linking magmatism with collision in an accretionary orogen

    PubMed Central

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A.; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-01-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251–245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen. PMID:27167207

  15. Linking magmatism with collision in an accretionary orogen

    NASA Astrophysics Data System (ADS)

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A.; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-05-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251–245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen.

  16. Linking magmatism with collision in an accretionary orogen.

    PubMed

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-01-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251-245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen. PMID:27167207

  17. MAGSAT anomaly map and continental drift

    NASA Technical Reports Server (NTRS)

    Lemouel, J. L. (Principal Investigator); Galdeano, A.; Ducruix, J.

    1981-01-01

    Anomaly maps of high quality are needed to display unambiguously the so called long wave length anomalies. The anomalies were analyzed in terms of continental drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic magnetized layer. Continental magnetic anomalies are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the anomalies found in India, Australia, and Antarctic exhibit a fair consistency with the African anomalies. It is also shown that anomalies are locked under the continents and have a fixed geometry.

  18. The Aravalli sequence of Rajasthan, India: A Precambrian continental margin?

    NASA Technical Reports Server (NTRS)

    Macdougall, J. D.; Willis, R.; Lugmair, G. W.; Roy, A. B.; Gopalan, K.

    1985-01-01

    The extent to which plate tectonics in its present form operated during the Precambrian is unknown, but is a subject of considerable current interest. A remarkable succession of Precambrian rocks in Rajasthan, Northwestern India, which may help to shed more light on this question are discussed. Data indicates that the Aravalli sequence has a number of characteristics generally ascribed to active continental margins. Although much more work is required to bear this out, the evidence suggests that the processes operating in such an environment in the early Proterozoic or late Archean were not vastly different from today.

  19. Atomic collisions, inelastic indeed

    NASA Astrophysics Data System (ADS)

    Bercegol, Herve; Ferrando, Gwenael; Lehoucq, Roland

    At the turn of the twentieth century, a hot controversy raged about the ability of Boltzmann's framework to take care of irreversibility. The so-called Loschmidt's paradox progressively faded with time during the last hundred years, due to the predictive efficiency of statistical mechanics. However, one detail at the origin of the controversy - the elasticity of atomic collisions - was not completely challenged. A semi-classical treatment of two atoms interacting with the vacuum zero-point field permits to predict a friction force acting against the rotation of the pair of atoms. By its form and its level, the calculated torque is a candidate as a physical cause for diffusion of energy and angular momentum, and consequently for entropy growth. It opens the way to a revision of the standard vision of irreversibility. This presentation will focus on two points. First we will discuss the recent result in a broader context of electromagnetic interactions during microscopic collisions. The predicted friction phenomenon can be compared to and distinguished from Collision-Induced Emission and other types of inelastic collisions. Second we will investigate the consequences of the friction torque on calculated trajectories of colliding atoms, quantifying the generation of dimers linked by dispersion forces.

  20. Photon-photon collisions

    SciTech Connect

    Brodsky, S.J.

    1988-07-01

    Highlights of the VIIIth International Workshop on Photon-Photon Collisions are reviewed. New experimental and theoretical results were reported in virtually every area of ..gamma gamma.. physics, particularly in exotic resonance production and tests of quantum chromodynamics where asymptotic freedom and factorization theorems provide predictions for both inclusive and exclusive ..gamma gamma.. reactions at high momentum transfer. 73 refs., 12 figs.

  1. Neutrino-atom collisions

    NASA Astrophysics Data System (ADS)

    Kouzakov, Konstantin A.; Studenikin, Alexander I.

    2016-05-01

    Neutrino-atom scattering provides a sensitive tool for probing nonstandard interactions of massive neutrinos in laboratory measurements. The ionization channel of this collision process plays an important role in experiments searching for neutrino magnetic moments. We discuss some theoretical aspects of atomic ionization by massive neutrinos. We also outline possible manifestations of neutrino electromagnetic properties in coherent elastic neutrino-nucleus scattering.

  2. Dating of the oldest continental sediments from the Himalayan foreland basin.

    PubMed

    Najman, Y; Pringle, M; Godin, L; Oliver, G

    2001-03-01

    A detailed knowledge of Himalayan development is important for our wider understanding of several global processes, ranging from models of plateau uplift to changes in oceanic chemistry and climate. Continental sediments 55 Myr old found in a foreland basin in Pakistan are, by more than 20 Myr, the oldest deposits thought to have been eroded from the Himalayan metamorphic mountain belt. This constraint on when erosion began has influenced models of the timing and diachrony of the India-Eurasia collision, timing and mechanisms of exhumation and uplift, as well as our general understanding of foreland basin dynamics. But the depositional age of these basin sediments was based on biostratigraphy from four intercalated marl units. Here we present dates of 257 detrital grains of white mica from this succession, using the 40Ar-39Ar method, and find that the largest concentration of ages are at 36-40 Myr. These dates are incompatible with the biostratigraphy unless the mineral ages have been reset, a possibility that we reject on the basis of a number of lines of evidence. A more detailed mapping of this formation suggests that the marl units are structurally intercalated with the continental sediments and accordingly that biostratigraphy cannot be used to date the clastic succession. The oldest continental foreland basin sediments containing metamorphic detritus eroded from the Himalaya orogeny therefore seem to be at least 15-20 Myr younger than previously believed, and models based on the older age must be re-evaluated. PMID:11242076

  3. Deep water challenges: Oil industry moves off continental shelf; meets new oceanographic data-gathering challenges

    SciTech Connect

    Mardell, G.; Flynn, J.

    1995-08-01

    While offshore oil industry activities move from the continental shelves to the continental slope and even onto the abyssal plains of the deep oceans, new oceanographic problems arise - from riser-deforming internal waves to ocean-floor avalanches. As well as soliton-induced currents, other subsurface flows need to be monitored to provide data in support of wide ranging underwater activities, including exploration drilling, deployment of subsea systems, diver and ROV operations, and pipe design, lay and inspection. This article examines some of the work carried out over the past year or so with data-gathering deep water moorings.

  4. Late Cenozoic tectonic development of the Southeast Asian continental margin in the Banda Sea area

    NASA Astrophysics Data System (ADS)

    Hartono, H. M. S.

    1990-09-01

    The late Cenozoic tectonic development of the Southeast Asian continental margin around the Banda Sea is complicated by interaction with external geological elements. Southeast Asian internal elements are the Banda Volcanic Arc and previous older arcs. External elements are the Australian continental crust and the Indian and Pacific oceanic crusts. These external elements are now trapped behind the Banda Volcanic Arc. Three main geological events are responsible for the present configuration of the Banda Sea and adjacent areas: (1) collision between the Banda Volcanic Arc and Australian continental crust; (2) emplacement of the Banda Sea oceanic crust; and (3) emplacement of microcontinents now present in and around the Banda Sea. The geology of Timor is fundamental to tectonic interpretations of the collision between the Banda Volcanic Arc and Australia. Differences exist in the tectonic interpretation of Timor and include either overthrusting, upthrusting or mélange formation. The present paper follows geological data contained in geological maps published by the Geological Survey of Indonesia in which overthrust structures are clearly shown. Paleomagnetic and paleontologic data indicate that the overthrust units were from southern paleolatitudes. Depth and magnetic lineation data support the interpretation that the Banda Sea is underlain by old oceanic crust. Similar orientation of magnetic lineations in the Banda Sea and the Argo Abyssal Plain suggests that they have the same origin. Geological data from northern Banda microcontinents, dredged samples from the Banda/Lucipara ridges and comprehensive geological development of the northern Banda Arc support the interpretation that the microcontinents were translated left-laterally westward from Irian Jaya.

  5. Differences between the internal energy depositions induced by collisional activation and by electron transfer of W(CO){sub 6}{sup 2+} ions on collision with Ar and K targets

    SciTech Connect

    Hayakawa, Shigeo; Kitaguchi, Akihiro; Kameoka, Satoko; Toyoda, Michisato; Ichihara, Toshio

    2006-06-14

    Doubly charged tungsten hexacarbonyl W(CO){sub 6}{sup 2+} ions were made to collide with Ar and K targets to give singly and doubly charged positive ions by collision-induced dissociation (CID). The resulting ions were analyzed and detected by using a spherical electrostatic analyzer. Whereas the doubly charged fragment ions resulting from collisional activation (CA) were dominant with the Ar target, singly charged fragment ions resulting from electron transfer were dominant with the K target. The internal energy deposition in collisionally activated dissociation (CAD) evaluated with the Ar target was broad and decreased with increasing internal energy. The predominant peaks observed with the K target were associated with singly charged W(CO){sub 2}{sup +} and W(CO){sub 3}{sup +} ions: these ions were not the result of CA, but arose from dissociation induced by electron transfer (DIET). The internal energy deposition resulting from the electron transfer was very narrow and centered at a particular energy, 7.8 eV below the energy level of the W(CO){sub 6}{sup 2+} ion. This narrow internal energy distribution was explained in terms of electron transfer by Landau-Zener [Z. Phys. Soviet 2, 46 (1932); Proc. R. Soc. London, Ser. A 137, 646 (1952)] potential crossing at a separation of 5.9x10{sup -8} cm between a W(CO){sub 6}{sup 2+} ion and a K atom, and the coulombic repulsion between singly charged ions in the exit channel. A large cross section of 1.1x10{sup -14} cm{sup 2} was estimated for electron capture of the doubly charged W(CO){sub 6}{sup 2+} ion from the alkali metal target, whose ionization energy is very low. The term ''collision-induced dissociation,'' taken literally, includes all dissociation processes induced by collision, and therefore encompasses both CAD and DIET processes in the present work. Although the terms CID and CAD have been defined similarly, we would like to propose that they should not be used interchangeably, on the basis that there are

  6. Notice of Release of 'Continental' Basin Wildrye

    Technology Transfer Automated Retrieval System (TEKTRAN)

    'Continental' basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Love) has been released as a cultivar for use in rangeland seedings. It was developed from a hybrid between an induced octoploid (2n=56), generated from the natural tetraploid 'Trailhead' (2n=28), and the natural octoploid 'Magnar' (...

  7. Eocene continental climates and latitudinal temperature gradients

    NASA Astrophysics Data System (ADS)

    Greenwood, David R.; Wing, Scott L.

    1995-11-01

    Global climate during the Mesozoic and early Cenozoic is thought to have been warmer than at present, but there is debate about winter temperatures. Paleontological data indicate mild temperatures even at high latitudes and in mid-latitude continental interiors, whereas computer simulations of continental paleoclimates produce winter temperatures closer to modern levels. Foliar physiognomy and floristic composition of 23 Eocene floras from the interior of North America and Australia indicate cold month means generally >2 °C, even where the mean annual temperature (MAT) was <15 °C. Reconstructed Eocene latitudinal gradients of MAT are curvilinear but are about 0.4 °C per 1° of latitude in continental interiors at mid-latitudes, much less than the 0.8 1.0 °C per 1° of latitude observed in eastern and central North America today, but similar to modern gradients in the Southern Hemisphere mid-latitudes and on the west coast of North America. Latitudinal temperature gradients reconstructed here are broadly representative of Eocene climates, showing that the discrepancy between proxy data and simulations will not be resolved by regional adjustments to paleogeography or reinterpretation of individual fossil assemblages. Similar discrepancies between proxy data and general circulation model simulations for other time periods suggest that there is a basic flaw with the way climate models simulate heat transport to, or loss from, continental surfaces.

  8. Plate Tectonics and Continental Drift: Classroom Ideas.

    ERIC Educational Resources Information Center

    Stout, Prentice K.

    1983-01-01

    Suggests various classroom studies related to plate tectonics and continental drift, including comments on and sources of resource materials useful in teaching the topics. A complete list of magazine articles on the topics from the Sawyer Marine Resource Collection may be obtained by contacting the author. (JN)

  9. Coordination: Southeast Continental Shelf studies. Progress report

    SciTech Connect

    Menzel, D.W.

    1981-02-01

    An overview of the Oceanograhic Program of Skidaway Institute of Oceanograhy is presented. Included are the current five year plan for studies of the Southeast Continental Shelf, a summary of research accomplishments, proposed research for 1981-1982, current status of the Savannah Navigational Light Tower, and a list of publications. (ACR)

  10. Elephant teeth from the atlantic continental shelf

    USGS Publications Warehouse

    Whitmore, F.C., Jr.; Emery, K.O.; Cooke, H.B.S.; Swift, D.J.P.

    1967-01-01

    Teeth of mastodons and mastodons have been recovered by fishermen from at least 40 sites on the continental shelf as deep as 120 meters. Also present are submerged shorelines, peat deposits, lagoonal shells, and relict sands. Evidently elephants and other large mammals ranged this region during the glacial stage of low sea level of the last 25.000 years.

  11. Deep observation and sampling of the earth's continental crust (DOSECC): Continental scientific drilling workshop

    SciTech Connect

    Not Available

    1985-01-01

    Research summaries are presented of ongoing or proposed deep drilling programs to explore hydrothermal systems, buried astroblemes, continental crust, magma systems, mountain belt tectonics, subduction zones, and volcanoes. Separate abstracts have been prepared for individual papers. (ACR)

  12. Total Probability of Collision as a Metric for Finite Conjunction Assessment and Collision Risk Management

    NASA Astrophysics Data System (ADS)

    Frigm, R.; Johnson, L.

    The Probability of Collision (Pc) has become a universal metric and statement of on-orbit collision risk. Although several flavors of the computation exist and are well-documented in the literature, the basic calculation requires the same input: estimates for the position, position uncertainty, and sizes of the two objects involved. The Pc is used operationally to make decisions on whether a given conjunction poses significant collision risk to the primary object (or space asset of concern). It is also used to determine necessity and degree of mitigative action (typically in the form of an orbital maneuver) to be performed. The predicted post-maneuver Pc also informs the maneuver planning process into regarding the timing, direction, and magnitude of the maneuver needed to mitigate the collision risk. Although the data sources, techniques, decision calculus, and workflows vary for different agencies and organizations, they all have a common thread. The standard conjunction assessment and collision risk concept of operations (CONOPS) predicts conjunctions, assesses the collision risk (typically, via the Pc), and plans and executes avoidance activities for conjunctions as a discrete events. As the space debris environment continues to increase and improvements are made to remote sensing capabilities and sensitivities to detect, track, and predict smaller debris objects, the number of conjunctions will in turn continue to increase. The expected order-of-magnitude increase in the number of predicted conjunctions will challenge the paradigm of treating each conjunction as a discrete event. The challenge will not be limited to workload issues, such as manpower and computing performance, but also the ability for satellite owner/operators to successfully execute their mission while also managing on-orbit collision risk. Executing a propulsive maneuver occasionally can easily be absorbed into the mission planning and operations tempo; whereas, continuously planning evasive

  13. The effect of rheological approximations on the dynamics and topography in 3D subduction-collision models

    NASA Astrophysics Data System (ADS)

    Pusok, Adina E.; Kaus, Boris J. P.; Popov, Anton A.

    2016-04-01

    Most of the major mountain belts and orogenic plateaus are found within the overlying plate of active or fossil subduction and/or collision zones. Moreover, they evolve differently from one another as the result of specific combinations of surface and mantle processes. These differences arise for several reasons, such as different rheological properties, different amounts of regional isostatic compensation, and different mechanisms by which forces are applied to the convergent plates. Previous 3D geodynamic models of subduction/collision processes have used various rheological approximations, making numerical results difficult to compare, since there is no clear image on the extent of these approximations on the dynamics. Here, we employ the code LaMEM to perform high-resolution long-term 3D simulations of subduction/continental collision in an integrated lithospheric and upper-mantle scale model. We test the effect of rheological approximations on mantle and lithosphere dynamics in a geometrically simplified model setup that resembles a tectonic map of the India-Asia collision zone. We use the "sticky-air" approach to allow for the development of topography and the dynamics of subduction and collision is entirely driven by slab-pull (i.e. "free subduction"). The models exhibit a wide range of behaviours depending on the rheological law employed: from linear to temperature-dependent visco-elasto-plastic rheology that takes into account both diffusion and dislocation creep. For example, we find that slab dynamics varies drastically between end member models: in viscous approximations, slab detachment is slow following a viscous thinning, while for a non-linear visco-elasto-plastic rheology, slab detachment is relatively fast, inducing strong mantle flow in the slab window. We also examine the stress states in the subducting and overriding plates and topography evolution in the upper plate, and we discuss the implications on lithosphere dynamics at convergent margins

  14. Reactive Collision Avoidance Algorithm

    NASA Technical Reports Server (NTRS)

    Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

    2010-01-01

    The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on

  15. Continental accretion: contrasting Mesozoic and Early Proterozoic tectonic regimes in North America

    NASA Astrophysics Data System (ADS)

    Condie, Kent C.; Chomiak, Beverly

    1996-11-01

    Juvenile continental crust was accreted to southern and western North America during the Early Proterozoic and Mesozoic, respectively. Graywacke, granite, granodiorite, and basalt comprise most of the accreted Early Proterozoic crust, whereas graywacke, andesite, basalt, and granodiorite comprise most of the Mesozoic crust. In addition, carbonates, ultramafics, pelagic sediments, and tonalite/diorite are minor but important components in the juvenile Mesozoic crust, whereas rhyolites are important in the Early Proterozoic crust. Mesozoic supracrustal rocks vary significantly in chemical composition, while Early Proterozoic supracrustals have a limited compositional range and exhibit a linear relation between many element concentrations suggesting a genetic linkage between accreted terranes. Although SiO 2, Al 2O 3, FeO, and incompatible elements are more enriched in Early Proterozoic than in Mesozoic supracrustal rocks, negative Eu anomalies are typical of rocks of both ages. Early Proterozoic granitoids are enriched in LILE (large ion lithophile elements) compared to Mesozoic granitoids, and granitoids of both ages of are enriched in LILE and have larger Eu anomalies than associated supracrustal rocks. Accreted Mesozoic upper crust is similar to andesite in chemical composition, and the bulk crust is similar to basaltic andesite. In contrast, accreted Early Proterozoic upper crust and bulk crust are similar to granodiorite and andesite, respectively. Incompatible elements are depleted in the Mesozoic compared to the Early Proterozoic crust, but both crustal types have negative NbTa anomalies. Depending on the composition assumed for the lower crust, both ages of crust have either very small or negligible Eu anomalies. Lifespans of the Early Proterozoic terranes (time interval between oldest rocks in a terrane and its collision with North America) are 20-80 My, whereas lifespans of Mesozoic terranes are 50-500 My, with most falling between 50 and 200 My. Within

  16. Curved orogen and syntaxes formation during subduction and collision

    NASA Astrophysics Data System (ADS)

    Bajolet, F.; Replumaz, A.; Faccenna, C.; Lainé, R.

    2012-04-01

    The sustained convergence between India and Asia with successive stages of oceanic subduction, continental subduction and continental collision has lead to the formation of the Tibetan plateau while the Himalayan orogenic front acquired an arcuate shape convex toward the South. The Indian plate is bounded by north-south strike-slip faults, which accommodate a large indentation of Asia, between two oceanic subductions, beneath Makran to the west, beneath Indonesia to the east. Two syntaxes formed at both east and west termination of the Himalayan orogenic front at the transition between Indian and Asian plates. In order to better understand this particular configuration, we performed analog experiments at the Laboratory of Experimental Tectonics of Roma TRE to simulate, at the scale of the mantle - lithosphere system, the mechanics of the indentation process. The configuration is set to drive the India indenter towards the Asian continent with a motor-controlled-piston, to simulate far field stresses necessary for indentation. In particular, we test (1) which geometry and rheological parameters favor arcuate orogen and syntaxes formation, (2) what are the consequences on the topography of both the orogenic front and the plateau, and (3) how they relate with the subduction/collision dynamics. The setup is composed of a subducting and an overriding plate made of visco-elastic silicone putty, floating on low-viscosity syrup simulating the asthenosphere. The subducting plate simulates an oceanic lithosphere followed by a continental indenter (analog for the Indian craton) flanked or not by oceans (analog for Makran and Indonesian domains), while the upper continental plate simulates the Tibetan plateau. Results show that the curvature of the orogen and syntaxes' formation are primarily controlled by the strength and gravitational potential energy of the upper plate, and the shape of the subducting plate. A relatively strong upper plate flanked by oceans leads to a

  17. Effects of rheological weakening by fluids and melts for defining geodynamic regimes of oceanic-continental subduction

    NASA Astrophysics Data System (ADS)

    Gerya, Taras; Meilick, Irena

    2010-05-01

    The dynamics of subduction under an active margin is analyzed by using a 2D coupled petrological-thermomechanical numerical model of an oceanic-continental subduction process. This model includes spontaneous slab bending, dehydration of the subducted crust, aqueous fluid transport, partial melting of both crustal and mantle rocks and melt extraction processes resulting in magmatic arc crust growth. Based on our models we identify the following five geodynamic regimes of subduction which may potentially from at active margins: (1) stable subduction with no backarc spreading center and without plumes in the mantle wedge, (2) retreating subduction with the focused backarc spreading center and without plumes, (3) retreating subduction with distributed intra-arc extension and trans-lithospheric sedimentary plumes, (4) advancing subduction with underplating (laterally extending) sub-lithospheric plumes, (5) stable to advancing subduction with stationary (laterally limited) sub-lithospheric plumes. Transitions between these different regimes are mainly caused by the concurrence of rheological weakening effects of (1) aqueous fluids percolating from the subducting slab into the mantle wedge and (2) melts propagating from the partially molten areas formed in the mantle wedge toward the surface. The aqueous fluids mainly affect the forearc region. Strong fluid-related weakening promotes plates decoupling and reduces subduction drag causing stacking of sediments in the accretion prism. In contrast, reduced weakening by fluids results in strong coupling of the plates and leads to advancing collision-like subduction with enhanced subduction erosion. Thickening of the overriding plate and large sedimentary plumes in the mantle wedge are the consequences. On the other hand, melts are extracted from the hot regions above the slab and rheologically weaken mainly the lithosphere below the arc controlling overriding plate extension/shortening processes. Strong rheological weakening

  18. GEO Collision Avoidance using a Service Vehicle

    NASA Astrophysics Data System (ADS)

    Duncan, M.; Concha, M.

    2013-09-01

    Space Situational Awareness (SSA) is defined as the knowledge and characterization of all aspects of space. SSA is now a fundamental and critical component of space operations. The increased dependence on our space assets has in turn lead to a greater need for accurate, near real-time knowledge of all space activities. Key areas of SSA include improved tracking of small objects, determining the intent of maneuvering spacecraft, identifying all potential high risk conjunction events, and leveraging non-traditional sensors in support of the SSA mission. As the size of the space object population grows, the number of collision avoidance maneuvers grows. Moreover, as the SSA mission evolves to near real-time assessment and analysis, the need for new, more sophisticated collision avoidance methods are required. This paper demonstrates the utility of using a service vehicle to perform collision avoidance maneuver for GEO satellites. We present the planning and execution details required to successfully execute a maneuver; given the traditional conjunction analysis timelines. Various operational constraints and scenarios are considered as part of the demonstration. Development of the collision avoidance strategy is created using SpaceNav's collision risk management tool suite. This study aims to determine the agility required of any proposed servicing capability to provide collision avoidance within traditional conjunction analysis and collision avoidance operations timelines. Key trades and analysis items are given to be: 1. How do we fuse the spacecraft state data with the tracking data collected from the proximity sensor that resides on the servicing spacecraft? 2. How do we deal with the possibility that the collision threat for the event may change as the time to close approach is reduced? 3. Perform trade space of maneuver/thrust time versus achievable change in the spacecraft's orbit. 4. Perform trade space of proximity of service vehicle to spacecraft versus time

  19. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General § 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  20. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  1. 75 FR 1076 - Outer Continental Shelf Civil Penalties

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-08

    ... Minerals Management Service Outer Continental Shelf Civil Penalties AGENCY: Minerals Management Service.... SUMMARY: The Outer Continental Shelf Lands Act requires the MMS to review the maximum daily civil penalty assessment for violations of regulations governing oil and gas operations in the Outer Continental Shelf...

  2. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General § 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  3. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  4. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  5. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General § 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  6. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  7. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General § 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  8. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Outer continental shelf pipelines. 195.9 Section... HAZARDOUS LIQUIDS BY PIPELINE General § 195.9 Outer continental shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf must identify on all their respective pipelines the specific...

  9. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Outer continental shelf pipelines. 192.10 Section... shelf pipelines. Operators of transportation pipelines on the Outer Continental Shelf (as defined in the Outer Continental Shelf Lands Act; 43 U.S.C. 1331) must identify on all their respective pipelines...

  10. Eu Anomalies Constrain Recycling of Lower Continental Crust

    NASA Astrophysics Data System (ADS)

    Tang, M.; Rudnick, R. L.; McDonough, W. F.; Gaschnig, R. M.; Huang, Y.

    2014-12-01

    Europium is fractionated from Sm and