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Sample records for aegean extensional province

  1. Temporal patterns of detachment faulting along Cycladic extensional metamorphic domes, Aegean region

    NASA Astrophysics Data System (ADS)

    Schneider, D. A.; Grasemann, B.; Heizler, M.; Vogel, H.; Iglseder, C.

    2007-12-01

    The Aegean region together with the surrounding mainland areas are known for Miocene to Recent active, notably extensional tectonics that are the result of the retreating Hellenic slab, gravitational collapse of the region and, since the Late Miocene to Early Pliocene, the westward escape of Anatolia relative to Eurasia. Project ACCEL (Aegean Core Complexes along an Extended Lithosphere) has collected an extensive modern structural dataset for the islands of Kea, Kithnos, and Serifos of the western Cyclades. On all three islands, crustal-scale, low-angle frictional-viscous shear zones have been identified and record strikingly consistent SSW-directed extensional kinematics together with a WNE-ESE shortening component. The geology of Kea is dominated by highly-strained, greenschist-facies schists, calc-silicates and marbles; a major, 100's m thick ultramylonite zone defines this northern island as a structural dome. White mica Ar-Ar thermochronometry performed on variably deformed units from different structural levels yield consistent Early Miocene (15-19 Ma) cooling ages across the entire island. Other pervasively deformed shallow crustal regions of the Cyclades (Tinos and Andros; b-type domes of Jolivet et al. 2004) also record similar Early Miocene cooling. Comparable geology and structure is exposed on Serifos although locally deformed under amphibolite-facies conditions and intruded in the south by a Late Miocene granodiorite. A major high strain zone that is present on the island is localized along an earlier (Late Eocene) granitic pluton. White micas from mylonites and gneisses along this shear zone and from rocks in the southern portion of the island yield Late Miocene (8-9 Ma) cooling ages, whereas greenschist-facies units in northern Serifos that are dominated by a different structural record of several phases of folding yield Oligocene (30-34 Ma) mica Ar-Ar cooling ages. Oligocene ages are similarly reported from Evvia and Sifnos, which are noted for

  2. How far the postorogenic extensional tectonics in the Aegean domain is symmetric?

    NASA Astrophysics Data System (ADS)

    Augier, Romain; Jolivet, Laurent; Gadenne, Leslie; Driussi, Olivier

    2013-04-01

    Current models to explain the finite geometry of the Aegean domain and the exhumation of the eclogite-bearing HP rocks in the Aegean domain rely on the recognition of a synorogenic exhumation regime followed by a postorogenic back-arc extension. A first generation of low-angle normal faults (LANF) developed during the subduction and the formation of the Hellenic Eocene orogenic wedge contemporaneously with the overthrusting of the Cycladic Blueschists over basement units. Other LANF were formed subsequently and accompanied the development of Metamorphic Core Complexes (MCC) during the collapse of the internal zones in the back-arc domain. Most of the stretching during postorogenic extension was accommodated by N-dipping LANF with N- to NE-sense of shear pertaining to the North Cycladic Detachment System (NCDS). More recently, the description of the top-to-the-south West Cycladic Detachment System (WCDS) resulted in a more symmetrical character of the postorogenic extension. However, the transition in time and space between these major structures, particularly the NCDS and the WCDS, which is a key question to understand the dynamics of the back-arc extension, remains widely unclear. The Folegandros-Sikinos area, whose tectonometamorphic evolution appears poorly constrained, is however quite exemplary of this discussion. Located to the south of the Cycladic Archipelago, at short distance from the WCDS last outcrop in Serifos Island, this area offers the opportunity to study both the synorogenic deformation preserved at the vicinity of the Cycladic basement and the structural transition between areas characterised by top-to-the-North and top-to-the-South kinematics during the postorogenic history. Based on an extensive field survey making the link between kinematics of the noncoaxial deformation and changing metamorphic conditions, we show that (1) a E-W syn-blueschists facies deformation is preserved within the HP lenses; (2) a penetrative, post-blueschists facies

  3. Tectono-stratigraphic evolution through successive extensional events of the Anydros Basin, hosting Kolumbo volcanic field at the Aegean Sea, Greece

    NASA Astrophysics Data System (ADS)

    Nomikou, P.; Hübscher, C.; Ruhnau, M.; Bejelou, K.

    2016-03-01

    The structural evolution of the South Aegean Sea is little explored due to the lack of marine seismic data. Our present day understanding is mainly based on some island outcrops and GPS measurements. In this study we discuss the rather incremental opening of the Anydros Basin in the Pliocene during six major tectonic pulses and the subsequent basin fill processes by interpreting seismic data and derived time isochore maps. Between the active pulses basin floor tilting persisted on a much lower rate. Seismic data illustrate the depositional processes in the emerging Anydros Basin. The observation of onlap fill strata, divergent reflection pattern, moat channels and contourite drifts imply that deposition was controlled by turbidity and contour currents as well as the tilting basin floor. The metamorphic Attico-Cycladic basement shows a rise that aligns along an NW-SE directed axis crossing Anydros island. This axis marks a structural change of the Santorini-Amorgos Ridge and thus represents a major structural boundary. Dip angles of NE-SW trending major faults, like the Santorini-Amorgos Fault, indicate normal faulting to be the superior mechanism forming the present horst and graben environment. Hence, the area is likely to be in a state of NW-SE directed extensional stresses forming the asymmetric graben structure of Anydros. Secondary fault clusters strike the same direction but show much steeper dip angles, possibly indicating strike-slip movement or resulting from deformational stresses along the hinge zones of the normal faults. The majority of the faults we discovered are located in the area of earthquake clusters, which is another indication of recent faulting. Ring faults around Kolumbo submarine volcano, result from caldera collapse and mark the diameter of the magma chamber approximately to 20 km.

  4. Enigmatic compressional structures in an extensional province: Eku field, OML 67, offshore Nigeria

    SciTech Connect

    Quinones, M.; Evans, R. ); Alofe, K.; Onyeise, B. )

    1996-01-01

    Acquisition of 3-D seismic data over OML 67-70 and a detailed reservoir description study done on the Eku field, have allowed identification of previously unrecognized compressional features. Situated within a depocenter between arcuate normal growth faults, the Eku structure consists of a shale-cored anticlinal fold and fold-and-thrust separated by a zone of lateral displacement. The crests of the folds have been eroded at a major unconformity at the base of the Qua Iboe shale (Early Pliocene). In the absence of definitive biostratigraphic data, correlations among the various fault-blocks are based on the character of sedimentary packages and sequences on wireline logs. Combined with analysis of the geometry of faults and folds, the correlations support a description of pulsatory movement of folding and faulting, that ultimately culminated in extensional reactivation of earlier regional extension and the not coincident. The effect of the anticipated reservoir sections, and deformation, both compressional, was gravity-driven and on shale detachments. A working hypothesis to explain the disparity in direction of earlier extension and subsequent compression is that thermal expansion that accompanied formation of the Cameroon volcanic line to the east of the Niger Delta in Miocene time, caused a change in the direction of structuring, allowing downslope gravity-driven compression to be superimposed on pre-existing extensional features.

  5. Enigmatic compressional structures in an extensional province: Eku field, OML 67, offshore Nigeria

    SciTech Connect

    Quinones, M.; Evans, R.; Alofe, K.; Onyeise, B.

    1996-12-31

    Acquisition of 3-D seismic data over OML 67-70 and a detailed reservoir description study done on the Eku field, have allowed identification of previously unrecognized compressional features. Situated within a depocenter between arcuate normal growth faults, the Eku structure consists of a shale-cored anticlinal fold and fold-and-thrust separated by a zone of lateral displacement. The crests of the folds have been eroded at a major unconformity at the base of the Qua Iboe shale (Early Pliocene). In the absence of definitive biostratigraphic data, correlations among the various fault-blocks are based on the character of sedimentary packages and sequences on wireline logs. Combined with analysis of the geometry of faults and folds, the correlations support a description of pulsatory movement of folding and faulting, that ultimately culminated in extensional reactivation of earlier regional extension and the not coincident. The effect of the anticipated reservoir sections, and deformation, both compressional, was gravity-driven and on shale detachments. A working hypothesis to explain the disparity in direction of earlier extension and subsequent compression is that thermal expansion that accompanied formation of the Cameroon volcanic line to the east of the Niger Delta in Miocene time, caused a change in the direction of structuring, allowing downslope gravity-driven compression to be superimposed on pre-existing extensional features.

  6. Central caldera collapse complex - implications for extensional tectonics for Basin and Range province

    SciTech Connect

    Koff, L.R.

    1987-08-01

    The Basin and Range Province, being one of the youngest tectonically rejuvenated terrains, exhibits a series of concentric patterns that are identifiable on a computerized, shaded, relief map. The concentric patterns in the Nevada and Utah portions of the Basin and Range coincide with the track of crustal plutonism and volcanism dating from the Cretaceous, and described in detail by G.P. Eaton in 1979. This observation implies a genetic relationship between plutonism and detected concentric patterns. Numerous geotectonic and economic implications are associated with observed concentric patterns. These patterns appear to be centers of crustal extension and rifting. A gravitational collapse of the overlying sedimentary strata into the spreading centers results in observed thrusting, block faulting, and segmentation, resulting in megacalderalike concentric rims. Most of the gravitational thrusting and imbrication is achieved by sedimentary plate movements on a low-angle detachment zone. This low-angle detachment zone, described by B. Wernicke in 1981, may be rooted in the lower crust. The economic implications for mineral and hydrocarbon exploration are enormous in this province. Many researchers have identified an association of mineral accumulations and oil production with areas where concentric rims intersect with each other, or with straight lineaments.

  7. Recovering the Linkage History of Large Faults from the Sediments of the Gulf of California Extensional Province

    NASA Astrophysics Data System (ADS)

    Contreras, J.; Martin-Barajas, A.; Herguera, J.; Dorsey, R.

    2003-12-01

    Analysis of the stratigraphy of sedimentary basins bounded by normal faults yield a wealth of information about how these brittle structures evolve through time forming array systems. However, mostly due to large uncertainties in the dating of sediments, little can be said about slip rates and how slip is accommodated during the interaction and linkage of normal faults. Cyclicity in sediments induced by Milankovitch climatic changes can be used as a very precise high-resolution stratigraphic chronometer, eliminating the problem of uncertainties in the dating. Therefore, the slip history of faults can be inferred with high accuracy. Here we present a cyclicity analysis of gamma-ray log from a borehole drilled in the Laguna Salada basin, a transtensional basin located in the Gulf of California extensional province. This has allowed us to establish its chronostratigraphy with a resolution of 50 kyr, from which the subsidence history of the Laguna Salada fault and its interaction with neighboring faults is recovered. We find that the long-term subsidence rate of the Laguna Salada basin has remained constant during the last 1.65 Ma (~1.4 mm/yr) in agreement with observations documented by other authors. However, our analysis reveals that at shorter timescales the subsidence history is composed of pulses lasting on average ~500 kyr. Subsidence rates during these pulses can vary by a factor of two with respect to the long-term subsidence rate. These pulses correlate with the breaking of the Laguna Salada Fault and the breaking of the Canon Rojo fault, a releasing stepover that links the Laguna Salada fault with the Canada David detachment to the south.

  8. Seismic reflection profiling across Tertiary extensional structures in the eastern Amargosa Desert, southern Nevada, Basin and Range province

    USGS Publications Warehouse

    Brocher, T.M.; Carr, M.D.; Fox, K.F.; Hart, P.E.

    1993-01-01

    Outcrops, shallow well control, and coincident geophysical surveys are used to interpret a seismic reflection profile in the Amargosa Desert, within the Basin and Range province, of southern Nevada. The seismic line crosses all or parts of three Tertiary subbasins, revealing that basin growth occurred by progressive shifts of basin-bounding faults. A shallow laterally continuous, flat-lying, low-frequency reflector, interpreted as a Tertiary basalt flow, suggests that little vertical deformation has occurred within the easternmost of the small Tertiary basins since the eruption of the flow about 10 million years ago. Moderately dipping reflections within the pre-Tertiary bedrock may image Mesozoic thrust faults. Doming of the lower crust resembles that observed elsewhere in the Basin and Range province and is consistent with ductile flow in the lower crust. -from Authors

  9. Magmatic-Hydrothermal Connections and Geothermal Potential in the Extensional Great Basin Province, Southwestern U.S., as Revealed Through Integrative MT Surveying

    NASA Astrophysics Data System (ADS)

    Wannamaker, P. E.; Maris, V.; Hasterok, D. P.; Doerner, W.

    2012-12-01

    Well-sampled magnetotelluric surveys collected across the actively extensional Great Basin tectonic province that extend into the stable Modoc Plateau/Klamath Mtns and Colorado Plateau domains reveal several apparent connections between resistivity, geochemical, and other geophysical observations. Great Basin coverage shows numerous highly conductive, sub-horizontal zones in the lower crust interpreted to represent magmatic underplating and hydrothermal fluid exsolution, corroborated by seismic surveying where coincident. Average depth to these zones is inversely correlated with rate of extension, with the relatively active subregions of northwestern Nevada and western Utah exhibiting relatively shallow depths of magmatic features. East-central Nevada possesses a relatively thick and resistant crust suggesting that the Eureka heat flow low is, at least in part, a valid indicator of deeper thermal state. The conductive deep crustal zones commonly have steep, dike-like conductors extending surfaceward, several of which appear to feed into recognized high-temperature geothermal systems. Diagnostic deep crustal and upper mantle gas isotopes (He, C, O) often show anomalous behavior over these zones. They suggest an increased contribution from deep magmatic sources to high temperature geothermal systems near-surface relative to previous understanding. Extensional systems generally form at favorable structural intersections that promote dilatency and steep fluid pathways. These observations have motivated new research studies aimed at identifying high-enthalpy geothermal systems in the Great Basin through integrated MT geophysical, geochemical and geological techniques. Results from the Coso, Dixie Valley and McGinness Hills geothermal systems are highlighted, representing well established and newly-developed systems. Where available, seismicity and zones of fluid production tend to occur along the margins between conductors and resistors. This suggests a model where

  10. Alkali basalts and leucitites in an extensional intracontinental plate setting: The late Cenozoic Calatrava Volcanic Province (central Spain)

    NASA Astrophysics Data System (ADS)

    Cebriá, J.-M.; López-Ruiz, J.

    1995-04-01

    The Calatrava Volcanic Province (CVP) of central Spain is characterised by a intracontinental plate magmatic association of leucitites, melilitites, nephelinites and olivine basalts extruded during the late Miocene to Quaternary. Most of the rocks represent relatively primitive magmas and less than 45% have experienced small degrees ( < 25%) of crystal fractionation. Melilitites, nephelinites and olivine basalts form a suite generated by variable degrees of partial melting ( F = 5-17%) of a nearly homogeneous enriched (up to x18 chondritic values for the highly incompatible elements and × 3 for the moderately incompatible) mantle source, composed of Ol+Opx+Cpx+Gt+Phl. The leucitites appear to be derived by low degrees of partial melting ( ~ 4%) from a different mantle source, characterized by higher Rb, Ba, K and 87Sr enrichment and the presence of residual apatite. Phlogopite contributed to the leucititic liquids in a higher proportion than in the basaltic suite whereas clinopyroxene participated in lower amounts. The geochemical characteristics of the primary liquids suggest a contribution from two source components: (1) a subcontinental lithospheric component which appears to be a strongly enriched garnet-lherzolite with phlogopite ± apatite and (2) an asthenospheric diapir component with characteristics similar to the HIMU reservoir. These conclusions combined with geophysical observations indicate that the CVP magmatism could develop in two stages. In a first stage, a HIMU-like mantle diapir would trigger magma generation in the overlying subcontinental lithosphere by melting of pervasive enriched streaks or veins with phlogopite + apatite, giving rise to small amounts of leucititic liquids and to initial extension of the upper crust. In subsequent steps the extension developed, the lithosphere becomes stripped of its enriched components and the asthenospheric diapir starts to melt giving rise to the basaltic liquids which are virtually OIB-like magmas. This

  11. Plate boundaries and extensional tectonics

    NASA Astrophysics Data System (ADS)

    Le Pichon, Xavier; Angelier, Jacques; Sibuet, Jean-claude

    1982-01-01

    The behaviour of the lithosphere under extensional strain is different whether the surface of the lithosphere is above or below the level that would be reached by the asthenosphere in its absence. Below this level, the continuity of the old lithosphere may be rapidly broken and oceanic accretion starts. Above this level, extensive thinning of the old lithosphère occurs until the level is reached, and then the asthenospheric material may break out to the surface. The thinning probably depends on the strain rate. Two extreme cases must be distinguished. For low strain rates: the lower lithosphere may be thinned by diapiric intrusions and lithospheric sinking; the upper one is much less affected, as occurs in the African Rifts or the Rhine Graben. For high strain rates, the whole lithosphère is thinned rather uniformly, as occurs in the Aegean region and probably on many continental margins. The greatest portion of the lithosphere is extended plastically, while the upper brittle portion, about 10 km thick, is extended by normal faulting. The pattern of faulting in these widely extended areas is compared to a pack of cards resting at an angle on a plane, with each card (tilted block) making a slight angle with the preceding one. Using this simple model, we discuss the case of the Pindos basin of the Hellenides. Similar intra-continental basins 150 to 400 km wide may be created before the subsidence increases sufficiently for oceanic accretion to begin. We point out that these basins are especially susceptible to compressional failure whenever the stress system changes from extensional to compressional. Consequently, many orogens are localized along such zones of earlier extension, as shown by geological studies of the Western Alpine system.

  12. ­Crustal Structure of the Western Anatolian Extensional Province: Evidence for a ductile lower crust through the joint inversion of Receiver Functions and Dispersion Data

    NASA Astrophysics Data System (ADS)

    Delph, J. R.; Kahraman, M.; Zandt, G.; Beck, S. L.; Ozacar, A. A.; Turkelli, N.

    2014-12-01

    Western Anatolia is one of the most seismically active regions in the world, undergoing broad N-S extension associated with the rollback of the Aegean slab in the south. This region is characterized by high heat-flow, recent volcanism, and core-complex formation. We use >3500 receiver functions from a dense array of 47 stations located in western Turkey and dispersion data from a recent regional-scale, ambient noise tomography study to invert for shear-wave velocity as a function of depth. Using this technique, we obtain an unprecedented three-dimensional shear-wave velocity model that characterizes the crust of western Turkey. We find a sharp Moho transition beneath much of western Anatolia, with crustal thickness varying from ~25 km near the Aegean Sea to ~35 km beneath the Fethiye Lobe correlating with the topography in western Turkey. The lower crust exhibits a relatively continuous ~10-15 km thick low shear-wave velocity layer (LVL) beneath most of western Anatolia, reaching velocities below 3.0 km/s in some places. The top of this LVL marks the lower boundary of crustal seismicity. These characteristics suggest that the lower crust in western Anatolia is behaving as a ductile solid, as seismic velocities in this range at lower crustal depths are indicative of the presence of fluids (possibly partial melts when considering the high heat-flow in the region). We propose that the lower crust in this region may be undergoing local crustal flow due to the N-S dominated stress regime, which led to the formation of the sharp, low-relief Moho observed in western Turkey. Across the Fethiye-Burdur Fault Zone, we see the slowest S-wave velocities in the lower crust, reaching ~2.8 km/s. Unlike elsewhere in western Turkey, this region has relatively low surficial heat-flow and no recent volcanism. Therefore, the anomaly in the Fethiye Lobe is likely due to a different mechanism than western Turkey. We also observe a very slow uppermost mantle beneath this region, with

  13. New constraints on the active tectonic deformation of the Aegean

    USGS Publications Warehouse

    Nyst, M.; Thatcher, W.

    2004-01-01

    Site velocities from six separate Global Positioning System (GPS) networks comprising 374 stations have been referred to a single common Eurasia-fixed reference frame to map the velocity distribution over the entire Aegean. We use the GPS velocity field to identify deforming regions, rigid elements, and potential microplate boundaries, and build upon previous work by others to initially specify rigid elements in central Greece, the South Aegean, Anatolia, and the Sea of Marmara. We apply an iterative approach, tentatively defining microplate boundaries, determining best fit rigid rotations, examining misfit patterns, and revising the boundaries to achieve a better match between model and data. Short-term seismic cycle effects are minor contaminants of the data that we remove when necessary to isolate the long-term kinematics. We find that present day Aegean deformation is due to the relative motions of four microplates and straining in several isolated zones internal to them. The RMS misfit of model to data is about 2-sigma, very good when compared to the typical match between coseismic fault models and GPS data. The simplicity of the microplate description of the deformation and its good fit to the GPS data are surprising and were not anticipated by previous work, which had suggested either many rigid elements or broad deforming zones that comprise much of the Aegean region. The isolated deforming zones are also unexpected and cannot be explained by the kinematics of the microplate motions. Strain rates within internally deforming zones are extensional and range from 30 to 50 nanostrain/year (nstrain/year, 10-9/year), 1 to 2 orders of magnitude lower than rates observed across the major microplate boundaries. Lower strain rates may exist elsewhere withi the microplates but are only resolved in Anatolia, where extension of 13 ?? 4 nstrain/ year is required by the data. Our results suggest that despite the detailed complexity of active continental deformation

  14. Parameters influencing the location and characteristics of volcanic eruptions in a youthful extensional setting: Insights from the Virunga Volcanic Province, in the Western Branch of the East African Rift System

    NASA Astrophysics Data System (ADS)

    Smets, Benoît; d'Oreye, Nicolas; Kervyn, Matthieu; Kervyn, François

    2016-04-01

    The East African Rift System (EARS) is often mentioned as the modern archetype for rifting and continental break-up (Calais et al., 2006, GSL Special Publication 259), showing the complex interaction between rift faults, magmatism and pre-existing structures of the basement. Volcanism in the EARS is characterized by very active volcanoes, several of them being among the most active on Earth (Wright et al., 2015, GRL 42). Such intense volcanic activity provides useful information to study the relationship between rifting, magmatism and volcanism. This is the case of the Virunga Volcanic Province (VVP) located in the central part of the Western Branch of the EARS, which hosts two of the most active African volcanoes, namely Nyiragongo and Nyamulagira. Despite the intense eruptive activity in the VVP, the spatial distribution of volcanism and its relationship with the extensional setting remain little known. Here we present a study of the interaction between tectonics, magmatism and volcanism at the scale of the Kivu rift section, where the VVP is located, and at the scale of a volcano, by studying the dense historical eruptive activity of Nyamulagira. Both the complex Precambrian basement and magmatism appear to contribute to the development of the Kivu rift. The presence of transfer zones north and south of the Lake Kivu rift basin favoured the development of volcanic provinces at these locations. Rift faults, including reactivated Precambrian structures influenced the location of volcanism within the volcanic provinces and the rift basin. At a more local scale, the historical eruptive activity of Nyamulagira highlights that, once a composite volcano developed, the gravitational stress field induced by edifice loading becomes the main parameter that influence the location, duration and lava volume of eruptions.

  15. Cenozoic extensional tectonics in western and central Anatolia, Turkey: Introduction

    NASA Astrophysics Data System (ADS)

    Çemen, İbrahim; Helvacı, Cahit; Ersoy, E. Yalçın

    2014-11-01

    It is our great pleasure to present this special issue of Tectonophysics on Cenozoic extensional tectonics in western and central Anatolia, Turkey (Fig. 1). The Cenozoic extension followed a series of continental collisions from the Late Cretaceous to the Eocene that led to the formation of the Vardar-İzmir-Ankara-Erzincan and Tauride suture zones as a part of the Alpine-Himalayan belt in Turkey and surrounding regions (Fig. 1). This type of post-collisional large-scale extensional tectonic may be "normal" for parts of collisional mountain belts due to gravitational collapse of over-thickened crust, or, alternatively, extension may be driven by other tectonic forces such as lateral extrusion or subducting slab roll-back. Many extensional features in western Anatolia continue into the Aegean Sea where they are more difficult to study as the access to outcrops is limited to a few islands. However, extensional structures and the rock units affected by them (Fig. 1) are well exposed in western and central Anatolia, Turkey, providing a natural laboratory to study the dynamics and consequences of crustal extension. The effects of post-collisional Cenozoic extension die out on the eastern part of central Anatolia to the east of the Ecemiş Fault Zone (Fig. 1).

  16. A comparison between two hydrothermally formed extensional environment related kaolin deposits: Balikesir-Duvertepe, Turkey and Kline Mountain, Sierra County, New Mexico

    SciTech Connect

    Isik, I.; Clark, K.F. . Dept. of Geological Sciences)

    1992-01-01

    Economically important and hydrothermally formed kaolin deposits are often found within rift lithologic units, formed as a result of interaction of physical and geochemical processes in the extensional environment. The kaolin deposits of Balikesir--Duvertepe, Turkey and Kline Mountain, Sierra County, New Mexico, studied herein, are examples of this type. The Balikesir--Duvertepe district has been known as the most productive kaolin district in Turkey. Total reserves are estimated at 15 million metric tons. Located in the active Simav Graben produced by the subduction of the African Plate under the Aegean region, the kaolin deposits occur irregularly and variably in quality as a result of hydrothermal alteration of Neogene tuffs. The Kline Mountain kaolin deposit was formed as a result of advanced argillic alteration on the southeastern edge of the Mogollon--Datil volcanic field, which is related to the extensional environment of Basin and Range province and the Rio Grande rift. Its reserve is reported as 200 million metric tons of altered tuffs. The two deposits show striking similarities: extensional related rock units, intense in situ hydrothermal alteration, mineral content, seismic activity, alunite contamination, chemical composition, and intense silicification. The deposits also display some differences: regional climate, the intensity of hydrothermal alteration and the elapsed time causing relatively complete replacement in the Turkish deposit compared to that in NM. The Balikesir--Duvertepe district has been the center of kaolin marketing for use chiefly in ceramic, paper, and white cement, while the Kline Mountain kaolin had been exploited primarily for paper and ceramic tile as a coating; and in the oil industry as a filler and absorbent material.

  17. A continuum model of continental deformation above subduction zones - Application to the Andes and the Aegean

    NASA Technical Reports Server (NTRS)

    Wdowinski, Shimon; O'Connell, Richard J.; England, Philip

    1989-01-01

    A continuum model of continental deformation above subduction zones was developed that combines the viscous sheet and the corner flow models; the continental lithosphere is described by a two-dimensional sheet model that considers basal drag resulting from the viscous asthenosphere flow underneath, and a corner flow model with a deforming overlying plate and a rigid subducting plate is used to calculate the shear traction that acts on the base of the lithosphere above a subduction zone. The continuum model is applied to the Andes and the Aegean deformations, which represent, respectively, compressional and extensional tectonic environments above subduction zones. The models predict that, in a compressional environment, a broad region of uplifted topography will tend to develop above a more steeply dippping slab, rather than above a shallower slab, in agreement with observations in the various segments of the central Andes. For an extensional environment, the model predicts that a zone of compression can develop near the trench, and that extensional strain rate can increase with distance from the trench, as is observed in the Aegean.

  18. Elastic-Anelastic properties beneath the Aegean inferred from long period Rayleigh Waves

    NASA Astrophysics Data System (ADS)

    Kassaras, I.; Louis, F.; Makropoulos, K.; Kaviris, G.

    2007-12-01

    This work is towards contributing to the better knowledge of the deep structure of the Aegean by introducing experimental elastic and anelastic parameters via the study of long period Rayleigh waves. For this scope path- average phase velocities and attenuation coefficients of fundamental Rayleigh waves crossing the Aegean were extracted over the period range 10-100 s. It is mean worth that it is the first time that anelastic parameters of the long period wavefield are determined for the region. The wavetrains were recorded at the broadband stations installed some years ago in the Aegean region for the SEISFAULTGREECE project. The stochastic inversion algorithm has been used to derive 36 path-average models of shear velocity and 19 path-average models of inverse shear Q down to 200 km. Average over the study region shear Q values at depths from 0 to 200 km range between 29±13. The observed low shear Q likely indicate that fluids reside in lower crustal, as well as upper mantle depths. Furthermore, the elastic and anelastic 1-D path-average models were combined in a continuous regionalization tomographic scheme to obtain a 3-D model of shear velocity variation down to 200 km and a 3-D model of inverse shear Q variation down to 120 km. The most prominent features in the tomograms are: a) A low shear velocity zone in the back-arc region, especially in the central and north Aegean. This region is located south of the North Aegean Trough (the western edge of the North Anatolian Fault) and correlates well with the derived anelastic tomograms which present high attenuation in this area. b) A high velocity/low attenuation zone in South Aegean indicating the subducted African lithosphere beneath the Aegean. The zone in central and north Aegean characterized by low velocities/high attenuation is compatible with a region of high extensional strain rates, recent volcanism and high heat flow. These observations suggest a hot or perhaps partially molten upper mantle and

  19. Development of ramp-flat structures during Aegean extension

    NASA Astrophysics Data System (ADS)

    Brun, Jean-Pierre; Sokoutis, Dimitrios

    2014-05-01

    Low-angle extensional shear is frequently observed in the Aegean metamorphic rocks. This deformation is commonly interpreted as being related to detachment at crustal scale, yet it often corresponds to ramp-flat extensional systems that, at many places, control the deposition of Neogene sedimentary basins. From a mechanical point of view, the development of a ramp-flat structure requires the presence of weak layers that can be activated as décollement between stronger rocks units. In the Aegean, the décollement generally develops within the upper brittle crust (i.e. with temperatures lower than about 400°C) that consists in recently exhumed metamorphic rocks. The process by which, these layers become weak enough to form efficient décollements in extension is somewhat intriguing and not well understood. In this contribution we examine the particular case of ramp-flat structures of the Southern Rhodope Core Complex that controlled the deposition of late Miocene to Pleistocene sediments in continental and marine basins. Field evidence is used to argue that the décollement corresponds to marble layers that separate orthogneisses at 2-3 km depth within an upper brittle crust whose thickness is around 5 km. Field observation and stable isotope measurements suggest that the ramp-flat structure observed on the island of Thassos occurred in a marble unit rich in fluids at a temperature of around 200°C. Using laboratory experiments, we explore the geometry of extensional structures (fault systems, rollovers, piggy-back basins…) that can develop at crustal-scale as a function of: i) décollement depth and dip, ii) number of décollements, and iii) strength contrast, between the décollement and overlying strong units. The results are compared with the situation observed in the Southern Rhodope Core Complex. We are convinced that the principles of ramp-flat extension discussed here have a strong potential of application in many other orogenic domains affected by large

  20. Quantum Ontology and Extensional Mereology

    NASA Astrophysics Data System (ADS)

    Calosi, Claudio; Fano, Vincenzo; Tarozzi, Gino

    2011-11-01

    The present paper has three closely related aims. We first argue that Agazzi's scientific realism about Quantum Mechanics is in line with Selleri's and Tarozzi's proposal of Quantum Waves. We then go on to formulate rigorously different metaphysical principles such as property compositional determinateness and mereological extensionalism. We argue that, contrary to widespread agreement, realism about Quantum Mechanics actually refutes only the former. Indeed we even formulate a new quantum mechanical argument in favor of extensionalism. We conclude by noting that, given the results of the work, Agazzi's particular attitude towards Quantum Mechanics is still one of the most promising theoretical perspectives.

  1. Deriving Extensional Spatial Composition Tables

    NASA Astrophysics Data System (ADS)

    El-Geresy, Baher; Abdelmoty, Alia I.; Ware, Andrew J.

    Spatial composition tables are fundamental tools for the realisation of qualitative spatial reasoning techniques. Studying the properties of these tables in relation to the spatial calculi they are based on is essential for understanding the applicability of these calculi and how they can be extended and generalised. An extensional interpretation of a spatial composition table is an important property that has been studied in the literature and is used to determine the validity of the table for the models it is proposed for. It provides means for consistency checking of ground sets of relations and for addressing spatial constraint satisfaction problems. Furthermore, two general conditions that can be used to test for extensionality of spatial composition tables are proposed and applied to the RCC8 composition table to verify the allowable models in this calculus.

  2. Extensional rheology of active suspensions

    NASA Astrophysics Data System (ADS)

    Saintillan, David

    2010-05-01

    A simple model is presented for the effective extensional rheology of a dilute suspension of active particles, such as self-propelled microswimmers, extending previous classical studies on suspensions of passive rodlike particles. Neglecting particle-particle hydrodynamic interactions, we characterize the configuration of the suspension by an orientation distribution, which satisfies a Fokker-Planck equation including the effects of an external flow field and of rotary diffusion. Knowledge of this orientation distribution then allows the determination of the particle extra stress as a configurational average of the force dipoles exerted by the particles on the fluid, which involve contributions from the imposed flow, rotary diffusion, and the permanent dipoles resulting from activity. Analytical expressions are obtained for the stress tensor in uniaxial extensional and compressional flows, as well as in planar extensional flow. In all types of flows, the effective viscosity is found to increase as a result of activity in suspensions of head-actuated swimmers (pullers) and to decrease in suspensions of tail-actuated swimmers (pushers). In the latter case, a negative particle viscosity is found to occur in weak flows. In planar extensional flow, we also characterize normal stresses, which are enhanced by activity in suspensions of pullers but reduced in suspensions of pushers. Finally, an energetic interpretation of the seemingly unphysical decrease in viscosity predicted in suspensions of pushers is proposed, where the decrease is explained as a consequence of the active power input generated by the swimming particles and is shown not to be directly related to viscous dissipative processes.

  3. Extensional rheology of active suspensions.

    PubMed

    Saintillan, David

    2010-05-01

    A simple model is presented for the effective extensional rheology of a dilute suspension of active particles, such as self-propelled microswimmers, extending previous classical studies on suspensions of passive rodlike particles. Neglecting particle-particle hydrodynamic interactions, we characterize the configuration of the suspension by an orientation distribution, which satisfies a Fokker-Planck equation including the effects of an external flow field and of rotary diffusion. Knowledge of this orientation distribution then allows the determination of the particle extra stress as a configurational average of the force dipoles exerted by the particles on the fluid, which involve contributions from the imposed flow, rotary diffusion, and the permanent dipoles resulting from activity. Analytical expressions are obtained for the stress tensor in uniaxial extensional and compressional flows, as well as in planar extensional flow. In all types of flows, the effective viscosity is found to increase as a result of activity in suspensions of head-actuated swimmers (pullers) and to decrease in suspensions of tail-actuated swimmers (pushers). In the latter case, a negative particle viscosity is found to occur in weak flows. In planar extensional flow, we also characterize normal stresses, which are enhanced by activity in suspensions of pullers but reduced in suspensions of pushers. Finally, an energetic interpretation of the seemingly unphysical decrease in viscosity predicted in suspensions of pushers is proposed, where the decrease is explained as a consequence of the active power input generated by the swimming particles and is shown not to be directly related to viscous dissipative processes.

  4. Aquatic animal resources in Prehistoric Aegean, Greece.

    PubMed

    Mylona, Dimitra

    2014-12-01

    This paper explores the early stages in the history of fishing in the Aegean Sea in Greece, and highlights its formative phases and its specific characteristics in different points in time. This is testified by various physical remains, such as fish bones, fishing tools, and representations in art, which are gathered in the course of archaeological research. The aquatic resources in the Aegean Sea have been exploited and managed for millennia by communities that lived near the water and often made a living from it. The earliest evidence for a systematic, intensive exploitation of marine resources in the Aegean Sea dates to the Mesolithic, eleven millennia ago. In the Neolithic period, the adoption of a sedentary, agro-pastoral way of life led to a reduction in the intensity of fishing and shellfish gathering. Its importance as an economic resource remained high only in certain regions of rich, eutrophic waters. In the Bronze Age, an era of social complexity and centralized economy, the exploitation of aquatic, mostly marine, resources became a complex, multi-faceted activity which involved subsistence, industry and ideology. The range of preferred fish and invertebrate species, the fishing technology, and the processing of fish and shellfish in order to produce elaborate foods or prestige items are all traceable aspects of the complex relationship between humans and the aquatic resources throughout the prehistory of fishing and shellfish gathering in the Aegean area. The broadening of collaboration between archaeology and physical sciences offers new means to explore these issues in a more thorough and nuanced manner.

  5. Geometry, thermal structure and kinematics of the metamorphic dome of Ikaria (eastern Cyclades, Greece): implication for Aegean tectonics

    NASA Astrophysics Data System (ADS)

    Beaudoin, Alexandre; Laurent, Valentin; Augier, Romain; Jolivet, Laurent; Lahfid, Abdeltif; Arbaret, Laurent; Rabillard, Aurélien

    2014-05-01

    The Aegean domain has been characterized since the Oligocene by extensional tectonics caused by the southward retreat of the African slab subducting beneath Eurasia. Structures and associated kinematics relative to this extensional tectonics are well constrained in the western Cyclades and the Menderes massif of western Turkey. Major extensional detachments such as the North Cycladic Detachment System (NCDS) or the Simav Detachment have accommodated the exhumation of a series of metamorphic core complexes (MCC) from Andros-Tinos-Mykonos in the west to the northern Menderes massif in the east. However, the transition between the NCDS and the Simav Detachment is currently not understood. This transition is located above a large-scale tear in the Aegean slab and its effects on the kinematics of deformation and P-T-t evolution of the overlying thinned crust are not known. The geology of Ikaria Island, located in this region, remains poorly known and the few existing studies are strikingly conflicting. This work attempts to clarify the geology of Ikaria by a new geological mapping and structural field study coupled with a thermometric study by Raman spectrometry of carbonaceous material (RSCM). Foliation over the whole island defines a structural dome, lately intruded by intrusive granitic bodies. Lineation shows a ca. N-S ductile stretching associated with an overall top-to-the-North sense of shear. Final exhumation of the dome was thus completed by a system of two top-to-the-North detachments, operating in the ductile and then the brittle fields. The proposed tectono-metamorphic evolution of the dome is consistent with the evolution of the northern Aegean area, suggesting that Ikaria belongs to the Aegean MCC and that the NCDS continues eastward. Besides, the distribution of RSCM temperatures within the dome and the presence of migmatites in the western part of the island comply with the description of migmatite-cored MCC such as Naxos or Mykonos. A better

  6. Inversion of Extensional Sedimentary Basins

    NASA Astrophysics Data System (ADS)

    Buiter, Susanne J. H.; Pfiffner, O. Adrian

    The evolution of extensional sedimentary basins is governed by the surrounding stress field and can, therefore, be expected to be highly sensitive to variations in these stresses. Important changes in basin geometry are to be expected in the case of an even short-lived reversal from extension to compression. We investigate the evolu- tion of fold and thrust structures which form in compression after extension, when basin forming processes have come to a complete stop. To this purpose, we use a two- dimensional, viscoplastic model and start our experiments from a pre-existing exten- sional geometry. We illustrate the sensitivity of the evolving structures to inherited extensional geometry, sedimentary and erosional processes, and material properties. One series of our model experiments involves the upper- to middle crust only in order to achieve a high detail in the basin area. We find that our results agree with examples from nature and analogue studies in, among others, the uplift and rotation of syn-rift sediments, the propagation of shear zones into the post-rift sediments and, in specific cases, the development of back-thrusts or basement short-cut faults. We test the out- come of these models by performing a second series of model simulations in which basins on a continental margin are inverted through their progressive approach of a subduction zone. These latter models are on the scale of the whole upper mantle.

  7. Variations in fault-slip data and cooling history reveal corridor of heterogeneous backarc extension in the eastern Aegean Sea region

    NASA Astrophysics Data System (ADS)

    Ring, Uwe; Gessner, Klaus; Thomson, Stuart

    2017-03-01

    We report fault-slip data across the boundary between the highly extended and largely submerged crust underlying the Aegean Sea from Samos in the north to eastern Crete in the south, and the much less extended and emergent crust of western Anatolia. We identify three brittle deformation increments, a late Miocene (mainly Pliocene) to Recent crustal stretching increment, an intermittent early to late Miocene shortening increment concurrent with extension and magmatism, and a Miocene extensional event. The youngest increment documents late Miocene to Recent NNE extension over large areas, but can locally also be oriented SE (Amorgos and Astipalea Islands), and ESE (eastern Crete) suggesting overall oblate strain geometry. The intermittent Miocene ( 24-5 Ma) fault-slip records suggest overall prolate strain geometry, where NNE stretching is accompanied by E-W shortening. The older extension event is mainly NNE directed but on Samos Island extension is E-W, probably reflecting local extension in a sinistral wrench corridor in the early/mid Miocene. Overall it seems that since the early Miocene NNE-trending extension is the dominant regime in the eastern Aegean with an intermittent component of short-lived E-W shortening. The existence of a corridor of heterogeneous crustal deformation - which is spatially associated with uncharacteristically old fission track ages - and the apparent change in strain geometry in time challenge concepts that propose that the eastern Aegean Sea and western Anatolia have been deformed as a continuous tectonic domain since the Miocene. We propose that the regional variation in extensional strain geometry resulted from a sinistral wrench component that was superimposed on the regional 'background' NNE extension by translation across a diffuse plate boundary. We conclude that the eastern shoreline of the Aegean Sea is controlled by a Miocene to Recent sinistral wrench corridor that accommodated movement between different lithospheric domains.

  8. Geometry and kinematics of extensional structural wedges

    NASA Astrophysics Data System (ADS)

    Gui, Baoling; He, Dengfa; Zhang, Yongsheng; Sun, Yanpeng; Huang, Jingyi; Zhang, Wenjun

    2017-03-01

    Structural wedges in the compressive environment have been recognized and studied in different locations. However, extension structural wedges are less well-understood. Based on the normal fault-bend folding theory and inclined shear model, this paper quantitatively analyses deformations related to extensional structural wedges and builds a series of geometric models for them. An extensional structural wedge is a fault-block held by two or more normal faults, the action of which would fold its overlying strata. Extensional structural wedges of different shapes will lead to different deformation results for the overlying strata, and this paper illustrates both the triangular and quadrangular wedges and their related deformations. This paper also discusses differences between the extensional structural wedges and the normal fault-bend-folding. By analysing two seismic sections from Langfang-Gu'an Sag, East China, this paper provides two natural examples of the triangular and quadrangular extensional structural wedges, where the models can reasonably explain the overlying distinct highs and lows without obvious faults. The establishment of a geometric model of extensional structural wedges can provide reference and theoretical bases for future quantitative analysis of deformations in the extensional environment.

  9. Microfluidic extensional rheometry using stagnation point flow

    PubMed Central

    2016-01-01

    Characterization of the extensional rheometry of fluids with complex microstructures is of great relevance to the optimization of a wide range of industrial applications and for understanding various natural processes, biological functions, and diseases. However, quantitative measurement of the extensional properties of complex fluids has proven elusive to researchers, particularly in the case of low viscosity, weakly elastic fluids. For some time, microfluidic platforms have been recognized as having the potential to fill this gap and various approaches have been proposed. This review begins with a general discussion of extensional viscosity and the requirements of an extensional rheometer, before various types of extensional rheometers (particularly those of microfluidic design) are critically discussed. A specific focus is placed on microfluidic stagnation point extensional flows generated by cross-slot type devices, for which some important developments have been reported during the last 10 years. Additional emphasis is placed on measurements made on relevant biological fluids. Finally, the operating limits of the cross-slot extensional rheometer (chiefly imposed by the onset of elastic and inertial flow instabilities) are discussed. PMID:27099647

  10. Microfluidic extensional rheometry using stagnation point flow.

    PubMed

    Haward, S J

    2016-07-01

    Characterization of the extensional rheometry of fluids with complex microstructures is of great relevance to the optimization of a wide range of industrial applications and for understanding various natural processes, biological functions, and diseases. However, quantitative measurement of the extensional properties of complex fluids has proven elusive to researchers, particularly in the case of low viscosity, weakly elastic fluids. For some time, microfluidic platforms have been recognized as having the potential to fill this gap and various approaches have been proposed. This review begins with a general discussion of extensional viscosity and the requirements of an extensional rheometer, before various types of extensional rheometers (particularly those of microfluidic design) are critically discussed. A specific focus is placed on microfluidic stagnation point extensional flows generated by cross-slot type devices, for which some important developments have been reported during the last 10 years. Additional emphasis is placed on measurements made on relevant biological fluids. Finally, the operating limits of the cross-slot extensional rheometer (chiefly imposed by the onset of elastic and inertial flow instabilities) are discussed.

  11. Extensional Rheology of Granular Staples

    NASA Astrophysics Data System (ADS)

    Franklin, Scott

    2013-03-01

    Collections of U-shaped granular materials (e.g. staples) show a surprising resistance to being pulled apart. We conduct extensional stress-strain experiments on staple piles with vary arm/spine (barb) ratio. The elongation is not smooth, with the pile growing in bursts, reminiscent of intruder motion through ordinary and rod-like granular materials. The force-distance curve shows a power-law scaling, consistent with previous intruder experiments. Surprisingly, there is significant plastic creep of the pile as particles rearrange slightly in response to the increasing force. There is a broad distribution of yield forces that does not seem to evolve as the pile lengthens, suggesting that each yield event is independent of the pile's history. The distribution of yield forces can be interpreted in the context of a Weibullian weakest-link theory that predicts the maximum pile strength to decrease sharply with increasing pile length. From this interpretation arise length and force scales that may be used to characterize the sample. This research supported in part by the NSF (CBET-#1133722) and ACS-PRF (#51438-UR10).

  12. Extensional scientific realism vs. intensional scientific realism.

    PubMed

    Park, Seungbae

    2016-10-01

    Extensional scientific realism is the view that each believable scientific theory is supported by the unique first-order evidence for it and that if we want to believe that it is true, we should rely on its unique first-order evidence. In contrast, intensional scientific realism is the view that all believable scientific theories have a common feature and that we should rely on it to determine whether a theory is believable or not. Fitzpatrick argues that extensional realism is immune, while intensional realism is not, to the pessimistic induction. I reply that if extensional realism overcomes the pessimistic induction at all, that is because it implicitly relies on the theoretical resource of intensional realism. I also argue that extensional realism, by nature, cannot embed a criterion for distinguishing between believable and unbelievable theories.

  13. Analytical chemistry in the Aegean Sea region: current status.

    PubMed

    Samanidou, Victoria F

    2012-12-01

    The Eighth Aegean Analytical Chemistry Days Conference took place in Urla, İzmir, Turkey, from 16-20 September 2012. This conference is held every 2 years, organized alternately by analytical chemistry departments of Turkish and Greek universities, so that analytical chemists from the region around the Aegean Sea can exchange experience and knowledge based on their research in a large number of fields. This report summarizes the most interesting presentations and posters pertaining to bioanalytical work.

  14. PREFACE: Donald D Harrington Symposium on the Geology of the Aegean

    NASA Astrophysics Data System (ADS)

    Catlos, Elizabeth J.

    2008-03-01

    This volume of the IOP Conference Series: Earth and Environmental Sciences presents a selection of papers given at the Donald D Harrington Symposium on the Geology of the Aegean held on the campus of the University of Texas at Austin on April 28-30, 2008. Donald D Harrington was born in Illinois in 1899 and moved westward after serving in the Army Air Corps during World War I. Mr Harrington took a position as a landman with Marlin Oil Company in Oklahoma. When the Texas Panhandle oil boom hit in 1926, he moved to Amarillo, Texas, where he met Sybil Buckingham—the granddaughter of one of Amarillo's founding families. They married in 1935 and went on to build one of the most successful independent oil and gas operations in Texas history. The couple created the Don and Sybil Harrington Foundation in 1951 to support worthy causes such as museums, medical research, education, and the arts. At the Harrington Symposium on the Geology of the Aegean, researchers presented papers organized under five general themes: (1) the geology of Aegean in general (2) the geologic history of specific domains within the Aegean (Cyclades, Menderes, Kazdag, Rhodope, Crete, southern Balkans, etc) (3) the dynamic tectonic processes that occur within the Aegean (4) its geo-archeological history, natural history and hazards and (5) comparisons of the Aegean to regions elsewhere (e.g., Basin and Ranges; Asian extensional terranes). The Aegean is a locus of dynamic research in a variety of fields, and the symposium provided an opportunity for geologists from a range of disciplines to interact and share new results and information about their research in the area. At the opening reception in the Harry S Ransom Center, Dr Clark Burchfiel (Massachusetts Institute of Technology, USA) provided a keynote address on the outstanding geologic problems of the Aegean region. His paper in this volume outlines a framework for future studies. We also call attention to a paper in this volume by Dr Y

  15. Late Miocene cooling and extension identified on Serifos, western Cyclades: Development of an Aegean metamorphic core complex

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Schneider, D. A.; Heizler, M.; Grasemann, B.; Iglseder, C.; ACCEL Team

    2007-12-01

    The island of Serifos is located in the Western Cyclades archipelago, a region noted for Miocene extension, where slab roll-back of the African-Arabian plate and gravitational collapse of a thickened crust has resulted in north-south to northeast-southwest directed extension. Bedrock lithologies on the island are composed of calc- silicates, schists, gneisses, and marbles metamorphosed to greenschist- to lower amphibolite-facies conditions. Project ACCEL (Aegean Core Complexes along an Extended Lithosphere) has recently documented a major low-angle shear zone consisting of (ultra)mylonitic marbles and orthogneisses with stretching lineations and kinematic indicators that record consistent SSW-directed extensional shear. The orthogneisses found within this shear zone are thought to be a syn-kinematic granite that yield preliminary U-Pb zircon rim ages of c. 37 Ma, suggesting a Late Eocene magmatic and deformation event. The southern part of the island is dominated by a largely undeformed, I-type granodiorite pluton of Late Miocene age. Serifos contains all the hallmarks of a classic Aegean metamorphic core complex, and a thermochronology campaign is underway to elucidate the timing of extension and unroofing. Analysis of fourteen mica separates using Ar-Ar thermochronmetry reveals two distinct cooling age populations, separated by a steep age gradient that is coincident with the well-defined shear zone in the northern region of the island. Samples taken from the southern units of the island, within the shear zone, and adjacent to the granodiorite pluton, give cooling ages of 8-9 Ma, illustrating bedrock cooling and exhumation coeval with intrusion of the granodiorite. Lower grade lithologies from the northern portion of the island yield mica cooling ages of 32-35 Ma. Eocene cooling ages present on Serifos are identical to deformation ages reported from the Cycladic Blueschist unit (CBU), present on nearby islands in the Cyclades and Evvia. The cooling and

  16. A new contribution to the Late Quaternary tephrostratigraphy of the Mediterranean: Aegean Sea core LC21

    NASA Astrophysics Data System (ADS)

    Satow, C.; Tomlinson, E. L.; Grant, K. M.; Albert, P. G.; Smith, V. C.; Manning, C. J.; Ottolini, L.; Wulf, S.; Rohling, E. J.; Lowe, J. J.; Blockley, S. P. E.; Menzies, M. A.

    2015-06-01

    Tephra layers preserved in marine sediments can contribute to the reconstruction of volcanic histories and potentially act as stratigraphic isochrons to link together environmental records. Recent developments in the detection of volcanic ash (tephra) at levels where none is macroscopically visible (so-called 'crypto-tephra') have greatly enhanced the potential of tephrostratigraphy for synchronising environmental and archaeological records by expanding the areas over which tephras are found. In this paper, crypto-tephra extraction techniques allow the recovery of 8 non-visible tephra layers to add to the 9 visible layers in a marine sediment core (LC21) from the SE Aegean Sea to form the longest, single core record of volcanic activity in the Aegean Sea. Using a novel, shard-specific methodology, sources of the tephra shards are identified on the basis of their major and trace element single-shard geochemistry, by comparison with geochemical data from proximal Mediterranean volcanic stratigraphies. The results indicate that the tephra layers are derived from 14 or 15 separate eruptions in the last ca 161 ka BP: 9 from Santorini; 2 or 3 from Kos, Yali, or Nisyros; 2 from the Campanian province; and one from Pantelleria. The attributions of these tephra layers indicate that 1) inter-Plinian eruptions from Santorini may have produced regionally significant tephra deposits, 2) marine tephrostratigraphies can provide unique and invaluable data to eruptive histories for island volcanoes, and 3) tephra from both Pantelleria and Campania may be used to correlate marine records from the Aegean Sea to those from the Tyrrhenian, Adriatic and Ionian Seas.

  17. On the geodynamics of the Aegean rift

    NASA Astrophysics Data System (ADS)

    Agostini, Samuele; Doglioni, Carlo; Innocenti, Fabrizio; Manetti, Piero; Tonarini, Sonia

    2010-06-01

    The Aegean rift is considered to be either a classic backarc basin, or the result of the westward escape of Anatolia, or the effect of a gravitational collapse of an over-thickened lithosphere. Here these models are questioned. We alternatively present a number of geodynamic and magmatic constraints suggesting a simple model for the genesis of the extension as being related to the differential advancement of the upper lithosphere over a heterogeneous lower African plate. The Greek microplate overrides the Ionian oceanic segment of the African plate faster than the Anatolian microplate over the thicker Levantine more continental segment. This setting is evidenced by GPS-velocity gradient in the hangingwall of the Hellenic-Cyprus subduction system and requires a zone of rifting splitting the hangingwall into two microplates. This mechanism is unrelated to the replacement of retreated slab by the asthenosphere as typically occurs in the backarc of west-directed subduction zones. The supposed greater dehydration of the Ionian segment of the slab is providing a larger amount of fluids into the low velocity channel at the top of the asthenosphere, allowing a faster decoupling between the Greek microplate and the underlying mantle with respect to the Anatolian microplate. Slab ruptures associated with the differential retreat controlled by the inherited lithospheric heterogeneities in the lower plate and the proposed upwelling of the mantle suggested by global circulation models would explain the occurrence and coexistence of slab-related and slab-unrelated magmatism.

  18. Shear and extensional properties of kefiran.

    PubMed

    Piermaría, Judith; Bengoechea, Carlos; Abraham, Analía Graciela; Guerrero, Antonio

    2016-11-05

    Kefiran is a neutral polysaccharide constituted by glucose and galactose produced by Lactobacillus kefiranofaciens. It is included into kefir grains and has several health promoting properties. In the present work, shear and extensional properties of different kefiran aqueous dispersions (0.5, 1 and 2% wt.) were assessed and compared to other neutral gums commonly used in food, cosmetic and pharmaceutics industries (methylcellulose, locust bean gum and guar gum). Kefiran showed shear flow characteristics similar to that displayed by other representative neutral gums, although it always yielded lower viscosities at a given concentration. For each gum system it was possible to find a correlation between dynamic and steady shear properties by a master curve including both the apparent and complex viscosities. When studying extensional properties of selected gums at 2% wt. by means of a capillary break-up rheometer, kefiran solutions did not show important extensional properties, displaying a behaviour close the Newtonian.

  19. Interactions between extensional shear zones and syn-tectonic granitic intrusions: the example of Ikaria Island (Cyclades, Greece)

    NASA Astrophysics Data System (ADS)

    Laurent, Valentin; Beaudoin, Alexandre; Jolivet, Laurent; Arbaret, Laurent; Augier, Romain; Rabillard, Aurelien

    2014-05-01

    The Aegean domain is an ideal place to investigate the development of Metamorphic Core Complex (MCC) and to study the role of syn-tectonic granites on their development. MCCs of the Aegean domain are dynamically associated with a few major detachments, especially the North Cycladic Detachment System (NCDS) and the West Cycladic Detachment System (WCDS), which have accommodated a large part of the crustal thinning during the Oligocene and Miocene. The NCDS extends toward the East within the Simav Detachment that has exhumed the northern high-temperature part of the Menderes massif. The transition between the NCDS and the Simav Detachments is located above a major tear in the Aegean slab whose effects on lithospheric deformation are far from understood. The Aegean granitoids were emplaced during the Middle Miocene within a zone of high-temperature during the episode of slab tearing and recorded increments of extensional tectonics within this complex zone. Ikaria Island (Cyclades, Greece) is a metamorphic dome intruded by three Miocene granitoid plutons (one I-type intrusion, two S-type ones) including the largest pluton of the Aegean domain. However, geometry, structures and kinematics are still debated with several recent yet conflicting studies. We have reconsidered the geology of Ikaria to settle the geological and structural context of these plutons. The intrusion depth of the Raches granite has been estimated at 10-15 km by the Al-in-hornblende barometer. Our field study has led to the identification of two major structures: the Gialiskari and Kalamos detachments, which we interpret as belonging to the NCDS. A study of deformation in the granites has highlighted a continuum during cooling that can be described in three stages: i) magmatic deformation, ii) high-temperature ductile deformation from late magmatic stage until complete crystallization of the granite, iii) low-temperature brittle deformation. Throughout this evolution, the same top-to-the-NE shearing

  20. Estimation of relative humidity based on artificial neural network approach in the Aegean Region of Turkey

    NASA Astrophysics Data System (ADS)

    Yasar, Abdulkadir; Simsek, Erdoğan; Bilgili, Mehmet; Yucel, Ahmet; Ilhan, Ilhami

    2012-01-01

    The aim of this study is to estimate the monthly mean relative humidity (MRH) values in the Aegean Region of Turkey with the help of the topographical and meteorological parameters based on artificial neural network (ANN) approach. The monthly MRH values were calculated from the measurement in the meteorological observing stations established in Izmir, Mugla, Aydin, Denizli, Usak, Manisa, Kutahya and Afyonkarahisar provinces between 2000 and 2006. Latitude, longitude, altitude, precipitation and months of the year were used in the input layer of the ANN network, while the MRH was used in output layer of the network. The ANN model was developed using MATLAB software, and then actual values were compared with those obtained by ANN and multi-linear regression methods. It seemed that the obtained values were in the acceptable error limits. It is concluded that the determination of relative humidity values is possible at any target point of the region where the measurement cannot be performed.

  1. Nestedness in centipede (Chilopoda) assemblages on continental islands (Aegean, Greece)

    NASA Astrophysics Data System (ADS)

    Simaiakis, Stylianos Michail; Martínez-Morales, Miguel Angel

    2010-05-01

    In natural ecosystems, species assemblages among isolated ecological communities such as continental islands often show a nested pattern in which biotas of sites with low species richness are non-random subsets of biotas of richer sites. The distribution of centipede (Chilopoda) species in the central and south Aegean archipelago was tested for nestedness. To achieve this aim we used distribution data for 53 species collected on 24 continental Aegean islands (Kyklades and Dodekanisa). Based on the first-order jackknife estimator, most of islands were comprehensively surveyed. In order to quantify nestedness, we used the nestedness temperature calculator (NTC) as well as the nestedness metric based on overlap and decreasing Fill (NODF). NTC indicated that data exhibited a high degree of nestedness in the central and south Aegean island complexes. As far as the Kyklades and Dodekanisa are concerned, NTC showed less nested centipede structures than the 24 islands. Likewise, NODF revealed a significant degree of nestedness in central and south Aegean islands. It also showed that biotas matrices without singletons were more nested than the complete ones (Aegean, Kyklades and Dodekanisa). The two commonest centipede taxa (lithobiomorphs and geophilomorphs) contributed differently to centipede assemblages. In the Kyklades and Dodekanisa, geophilomorphs did not show a reliable nested arrangement unlike lithobiomorphs. In relation to the entire data set, nestedness was positively associated with the degree of isolation. In the Kyklades altitudinal range best explained nestedness patterns, while in Dodekanisa habitat heterogeneity proved to be more important for the centipede communities. Island area does not seem to be a significant explanatory variable. Some of our results from the Kyklades were critically compared with those for terrestrial isopod and land snail nested assemblages from the same geographical area. The complex geological and palaeogeographical history of

  2. Hyperbolic contraction measuring systems for extensional flow

    NASA Astrophysics Data System (ADS)

    Nyström, M.; Tamaddon Jahromi, H. R.; Stading, M.; Webster, M. F.

    2017-02-01

    In this paper an experimental method for extensional measurements on medium viscosity fluids in contraction flow is evaluated through numerical simulations and experimental measurements. This measuring technique measures the pressure drop over a hyperbolic contraction, caused by fluid extension and fluid shear, where the extensional component is assumed to dominate. The present evaluative work advances our previous studies on this experimental method by introducing several contraction ratios and addressing different constitutive models of varying shear and extensional response. The constitutive models included are those of the constant viscosity Oldroyd-B and FENE-CR models, and the shear-thinning LPTT model. Examining the results, the impact of shear and first normal stress difference on the measured pressure drop are studied through numerical pressure drop predictions. In addition, stream function patterns are investigated to detect vortex development and influence of contraction ratio. The numerical predictions are further related to experimental measurements for the flow through a 15:1 contraction ratio with three different test fluids. The measured pressure drops are observed to exhibit the same trends as predicted in the numerical simulations, offering close correlation and tight predictive windows for experimental data capture. This result has demonstrated that the hyperbolic contraction flow is well able to detect such elastic fluid properties and that this is matched by numerical predictions in evaluation of their flow response. The hyperbolical contraction flow technique is commended for its distinct benefits: it is straightforward and simple to perform, the Hencky strain can be set by changing contraction ratio, non-homogeneous fluids can be tested, and one can directly determine the degree of elastic fluid behaviour. Based on matching of viscometric extensional viscosity response for FENE-CR and LPTT models, a decline is predicted in pressure drop for

  3. Extensional duplex in the Purcell Mountains of southeastern British Columbia

    SciTech Connect

    Root, K.G. )

    1990-05-01

    An extensional duplex consisting of fault-bounded blocks (horses) located between how-angle normal faults is exposed in Proterozoic strata in the Purcell Mountains of British Columbia, Canada. This is one of the first documented extensional duplexes, and it is geometrically and kinematically analogous to duplexes developed in contractional and strike-slip fault systems. The duplex formed within an extensional fault with a ramp and flat geometry when horses were sliced from the ramp and transported within the fault system.

  4. Extensional and compressional regime driven left-lateral shear in southwestern Anatolia (eastern Mediterranean): The Burdur-Fethiye Shear Zone

    NASA Astrophysics Data System (ADS)

    Elitez, İrem; Yaltırak, Cenk; Aktuğ, Bahadır

    2016-10-01

    The tectonic framework of the eastern Mediterranean presented in this paper is based on an active subduction and small underwater hills/mountains on the oceanic crust moving toward the north. The Hellenic Arc, the Anaximander Mountains, the Rhodes and Finike basins, the compressional southern regions of the Western Taurides, and the extensional western Anatolian graben are the main interrelated tectonic structures that are shaped by the complex tectonic regimes. There are still heated debates regarding the structural properties and tectonic evolution of the southwestern Anatolia. GPS velocities and focal mechanisms of earthquakes demonstrate the absence of a single transform fault across the Burdur-Fethiye region; however, hundreds of small faults showing normal and left-lateral oblique slip indicate the presence of a regionally extensive shear zone in southwestern Turkey, which plays an important role in the eastern Mediterranean tectonics. The 300-km-long, 75-90-km-wide NE-SW-trending Burdur-Fethiye Shear Zone developed during the formation of Aegean back-arc extensional system and the thrusting of Western Taurides. Today, the left-lateral differential motion across the Burdur-Fethiye Shear Zone varies from 3 to 4 mm/yr in the north to 8-10 mm/yr in the south. This finding could be attributed to the fact that while the subduction of the African Plate is relatively fast beneath the western Anatolia at the Hellenic Trench, it is slow or locked beneath the Western Taurides. Therefore, the GPS vectors and their distributions on land indicate remarkable velocity differences and enable us to determine the left-lateral shear zone located between the extensional and compressional blocks. Furthermore, this active tectonic regime creates differences in topography. This study also demonstrates how deep structures, such as the continuation of the subduction transform edge propagator (STEP) fault between the Hellenic and Cyprus arcs in the continental area, can come into play

  5. Symmetry during the syn- and post-rift evolution of extensional back-arc basins: The role of inherited orogenic structures

    NASA Astrophysics Data System (ADS)

    Balázs, Attila; Burov, Evgueni; Matenco, Liviu; Vogt, Katharina; Francois, Thomas; Cloetingh, Sierd

    2017-03-01

    Rheological heterogeneities in the lithosphere have first order control on the topographical expression of tectonic processes. Pre-existing orogenic suture zones localise extensional deformation resulting in asymmetric basins. Such crustal geometries are often in contrast with the more symmetric regional lithospheric structure observed beneath extensional basins. We study such (a)symmetries and their controlling parameters by conducting a series of 2D thermo-mechanical numerical experiments of the extension of an overthickened, hot lithosphere that contains a weakness zone. The modelling shows that syn-rift subsidence is low to moderate creating asymmetric half grabens where extension migrates in space and time, grouped in an overall symmetrical appearance on a larger scale. The initial lithospheric mantle asymmetry is attenuated by the lateral heat conduction and further dynamic evolution of the thermal anomaly during the "post-rift" phase, resulting in differential vertical movements of the crust including additional 2-3 km subsidence in the basin centre. The modelling shows that the initial crustal and lithospheric thicknesses, rate of extension and surface processes strongly control the thermo-mechanical evolution of the extensional system. The numerical modelling yields new insights into the mechanics of coupling between near-surface kinematics and the evolution of deep lithospheric structure in the Pannonian basin and the Aegean, two of Europe's largest back-arc systems.

  6. Extensional properties of mobile polymer solutions

    NASA Astrophysics Data System (ADS)

    Tirel, Christophe; Renoult, Marie-Charlotte; Dumouchel, Christophe; Crumeyrolle, Olivier; Lisiecki, Denis; Mutabazi, Innocent

    2016-11-01

    A deep understanding of the influence of viscoelasticity on the dynamics of liquid flows remains a challenge in the non-Newtonian fluid mechanics field. Previous work has revealed that the addition of minute amount (2.5 part per million) of high molecular weight polymer to water, forming a viscoelastic solution with strong extensional properties, modifies the fission process during droplet snap off with spectacular effects: inhibition of the singularity observed in the reference Newtonian case and formation of a long-lived (milli-second) filament. The measurement of the extensional properties for such mobile polymer solutions is one of the most pressing problem. Here, a global measurement technique, based on the multi-scale analysis of the capillary instability of a free falling jet of a mobile polymer solution, is introduced. The method of analysis allows the characterisation of the jet breakup mechanism from which the relaxation time of the polymer solution can be extracted. One of the advantages of the technique is the simple experiment it requires.

  7. Extensional tectonics on continents and the transport of heat and matter

    NASA Technical Reports Server (NTRS)

    Neugebauer, H. J.

    1985-01-01

    Intracontinental zones of extensional tectonic style are commonly of finite width and length. Associated sedimentary troughs are fault-controlled. The evolution of those structures is accompanied by volcanic activity of variable intensity. The characteristic surface structures are usually underlaid by a lower crust of the transitional type while deeper subcustal areas show delayed travel times of seismic waves especially at young tectonic provinces. A correspondence between deep-seated processes and zones of continental extension appears obvious. A sequential order of mechanisms and their importance are discussed in the light of modern data compilations and quantitative kinematic and dynamic approaches. The Cenozoic exensional tectonics related with the Rhine River are discussed.

  8. Contemporary kinematics of the southern Aegean and the Mediterranean Ridge

    NASA Astrophysics Data System (ADS)

    Kreemer, Corné; Chamot-Rooke, Nicolas

    2004-06-01

    This study focuses on the kinematics of the southern Aegean and the Mediterranean Ridge (MR). A quantification of the deformation of the MR is essential for both evaluating physical models of accretionary wedges in general and for obtaining a self-consistent model of the surface deformation over the entire Nubia-Eurasia (NU-EU) plate boundary zone in the eastern Mediterranean. Previous kinematic studies have not properly considered the deformation field south of the Hellenic arc. Although this study focuses on the deformation field of the MR, we also discuss the kinematics of the southern Aegean, because the geometry and movement of the Hellenic arc determine to a large extent the kinematic boundary conditions for kinematic studies of the MR. We calculate a continuous velocity and strain rate field by interpolating model velocities that are fitted in a least-squares sense to published Global Positioning System (GPS) velocities. In the interpolation, we use information from a detailed data set of onshore and offshore active faulting to place constraints on the expected style and direction of the model strain rate field. In addition, we use the orientations of tracks left by seamounts travelling into the wedge to further constrain the offshore deformation pattern. Our model results highlight the presence of active shear partitioning within the Mediterranean ridge. High compressional strain rates between the ridge crest and the deformation front accommodate approximately 60-70 per cent of the total motion over the wedge, and the outward growth rate of the frontal thrust is ~ 4 mm yr-1. Strain partitioning within the wedge leads to 19-23 mm yr-1 of dextral motion at the wedge-backstop contact of the western MR, whereas the Pliny and Strabo trenches in the eastern MR accommodate 21-23 mm yr-1 of sinistral motion. The backstop of the western MR is kinematically part of the southern Aegean, which moves as a single block [the Aegean block (AE)] at 33-34 mm yr-1 in the

  9. Magmatic Trigger for Extensional Collapse? Character and Significance of Pre-Extensional Volcanic Activity in the Whipple Mountains Region, Lower Colorado River Extensional Corridor

    NASA Astrophysics Data System (ADS)

    Fidler, M. K.; Gans, P. B.

    2014-12-01

    The character and timing of voluminous Miocene volcanic activity associated with regional crustal extension in the lower Colorado River Extensional Corridor (CREC) shed light on the interplay between tectonic and magmatic processes in the area. New 40Ar/39Ar ages from holocrystaline groundmass separates of mafic lava flows and phenocrystic plagioclase, biotite, hornblende, and sanidine from silicic extrusive rocks, combined with LA-ICPMS U-Pb ages of zircon from the more altered intermediate to silicic rocks provide important new constraints on the ages of pre-, syn-, and post-extensional volcanic sequences in the vicinity of the Whipple Mountains metamorphic core complex. Local eruptive activity began ~20.5 Ma and persisted for 1.5 million years prior to the inception of major extensional faulting and tilting at ~19 Ma, as recorded by upper plate tilt blocks. The pre-extensional sequences are homoclinal, steeply tilted, and disconformably overlie older arkosic sedimentary rocks. There is no compelling evidence for angular unconformities or growth faulting during this earliest pre-extensional volcanic activity. These early erupted units are dominantly mafic, forming ≥1 km thick sections of olivine-basalt and olv-cpx-plag basaltic andesite lava flows punctuated by rare aphyric to crystal poor dacite ignimbrites. Plag±pyx±bio±hbl dacite lava flows and domes with associated pyroclastic deposits appear late in the pre-extensional sequence, immediately prior to and during the onset of major extensional faulting. These crystal-poor to aphyric silicic rocks show abundant evidence of magma mingling and may represent hybridized partial melts generated by the influx of basaltic magma into the crust. The pre-extensional sequence is locally overlain by ~18.5 to 18.8 Ma syn- and post-extensional volcanic and sedimentary rocks along a pronounced 30-60° angular unconformity, indicating very rapid extension during the early stages of the CREC's development. This overall

  10. Simultaneous active control of flexural and extensional waves in beams

    NASA Technical Reports Server (NTRS)

    Fuller, C. R.; Gibbs, G. P.; Silcox, R. J.

    1990-01-01

    The simultaneous active control of flexural and extensional vibrations in elastic beams is experimentally investigated. The results demonstrate that using pairs of piezoceramic transducers, whose elements are symmetrically located and independently controlled by a multichannel adaptive controller, enables the high attenuation of both flexural and extensional response. This capability is due to the nature of the piezoceramic element, which when bonded to the surface of the structure and electrically excited, exerts a surface strain on the structure. This strain enables input of both shear forces and moments into the structural system. The results are applicable to many situations where extensional vibrations couple to large flexural vibrations and subsequently radiate significant sound levels.

  11. Shear zones developed between extensional and compressional tectonic regimes: recent deformation of the Burdur Fethiye Shear Zone as a case study

    NASA Astrophysics Data System (ADS)

    Elitez, İrem; Yaltırak, Cenk; Aktuǧ, Bahadır

    2016-04-01

    The southwestern Turkey is one of the most tectonically active areas of the eastern Mediterranean and therefore is a controversial region from the geodynamic point of view. This complex tectonic regime is dominated by the westward escape of Anatolia related to North Anatolian Fault, Aegean back-arc extension regime due to roll-back of Hellenic Arc, the subduction transform edge propagator (STEP) fault zone related to the motion of Hellenic and Cyprus arcs and compressional regime of Tauride Mountains. In addition to that, an active subduction and seamounts moving towards the north determine the tectonic frame of the Eastern Mediterranean. Many researchers suggest either the existence of a single left lateral fault or the nonexistence of a fault zone between Western Anatolia and Western Taurides. According to the integration of digital elevation data, non-commercial GoogleEarth satellite images and field studies, a 300 km-long 75-90 km-wide NE-SW-trending left lateral shear zone, the Burdur-Fethiye Shear Zone, is located among these tectonic structures. By using GPS velocities and focal mechanism solutions of earthquakes, it is understood that most of the previous studies turn a blind eye to the hundreds of faults related to a left-lateral shear zone which will have an important role in the Mediterrenean tectonics. The Burdur-Fethiye Shear Zone is like a zipper driven by the relative velocity differences due to the Aegean back-arc extensional system and Western Taurides compressional region and presents a high seismic activity. The GPS vectors reflect remarkable velocity differences on land and relatedly the significant topographic differences can be clearly observed. According to the GPS vectors, the Aegean region moves 4-12 mm/yr faster than the wesward escape of the Anatolia towards southwest and the velocities are low in the Western Taurides. The left-lateral differential motion across the Burdur-Fethiye Shear Zone varies from 3-4 mm/yr in the north side to 8

  12. The Termination Of The Northwest Basin And Range Into A Northwest Trending Extensional Fault System

    NASA Astrophysics Data System (ADS)

    Trench, D.; Meigs, A.

    2007-12-01

    Extensional provinces terminate along-strike where extension dissipates to zero, at transform faults, or at triple junctions. Termination of the northern Basin and Range province in western North America has long been thought to be controlled by an intracontinental transform fault, the Brothers Fault zone (BFz). New mapping in the boundary region between a major Basin and Range fault, the Hart Mountain fault system (HFz), and the BFz was conducted to test this model and to determine the structural and temporal relationship between the two fault zones. Stratigraphic separation and topography were used to determine fault orientations, displacement gradients, and sense of motion in the two fault zones. N-S trending faults of the HFz show predominantly normal displacement. Displacement in the HFz decreases northward from a maximum of ~940 m at Hart Mountain to ~173 m to 0 m at the BFz. Fault orientations smoothly change from the N-S Basin and Range trend in the south to the NW BFz trend in the north. Topography and stratigraphic separation indicate that the BFz is a series of isolated faults with maximum slip of ~106 m and lengths of up to a few kilometers. Piercing points within the BFz indicate that down-to-the-north motion predominates with the fault system and that strike-slip motion is minimal. Uncertainty on observed fault displacements is + 5m. Stratigraphic separation of the Rattlesnake Tuff indicates that activity on the NW trending fault system post-dates the 7 Ma tuff. That displacement along the HFz effectively goes to zero at the BFz suggests Basin and Range faults have propagated northward into an existing northeast- facing extensional province represented by the BFz.

  13. Assimilating Ferry Box data into the Aegean Sea model

    NASA Astrophysics Data System (ADS)

    Korres, G.; Ntoumas, M.; Potiris, M.; Petihakis, G.

    2014-12-01

    Operational monitoring and forecasting of marine environmental conditions is a necessary tool for the effective management and protection of the marine ecosystem. It requires the use of multi-variable real-time measurements combined with advanced physical and ecological numerical models. Towards this, a FerryBox system was originally installed and operated in the route Piraeus-Heraklion in 2003 for one year. Early 2012 the system was upgraded and moved to a new high-speed ferry traveling daily in the same route as before. This route is by large traversing the Cretan Sea being the largest and deepest basin (2500 m) in the south Aegean Sea. The HCMR Ferry Box is today the only one in the Mediterranean and thus it can be considered as a pilot case. The analysis of FerryBox SST and SSS in situ data revealed the presence of important regional and sub-basin scale physical phenomena, such as wind-driven coastal upwelling and the presence of a mesoscale cyclone to the north of Crete. In order to assess the impact of the FerryBox SST data in constraining the Aegean Sea hydrodynamic model which is part of the POSEIDON forecasting system, the in situ data were assimilated using an advanced multivariate assimilation scheme based on the Singular Evolutive Extended Kalman (SEEK) filter, a simplified square-root extended Kalman filter that operates with low-rank error covariance matrices as a way to reduce the computational burden. Thus during the period mid-August 2012-mid January 2013 in addition to the standard assimilating parameters, daily SST data along the ferryboat route from Piraeus to Heraklion were assimilated into the model. Inter-comparisons between the control run of the system (model run that uses only the standard data set of observations) and the experiment where the observational data set is augmented with the FerryBox SST data produce interesting results. Apart from the improvement of the SST error, the additional assimilation of daily of FerryBox SST

  14. An integrated approach to teaching Aegean archaeology and archaeological science

    NASA Astrophysics Data System (ADS)

    Pitcairn, Erica Glenn

    Outlined here is a course that would serve as an introduction to archaeological science, specifically within the context of Aegean Prehistory. The main objective of this course is to expose students early in their archaeological careers to a variety of methods and questions, and to depart from the culture-historical perspective that typifies introductory survey courses. The class structure is equal parts lecture and discussion, moving between learning how the methods work and evaluating case studies. All graded assignments build on one another, guiding the students through designing their own research project. The ultimate goals of the assignments are to build key writing and professional skills, develop a basic understanding of research design, and to instill confidence that the student can contribute to the production of knowledge, whatever field he or she decides to pursue.

  15. Early farmers from across Europe directly descended from Neolithic Aegeans.

    PubMed

    Hofmanová, Zuzana; Kreutzer, Susanne; Hellenthal, Garrett; Sell, Christian; Diekmann, Yoan; Díez-Del-Molino, David; van Dorp, Lucy; López, Saioa; Kousathanas, Athanasios; Link, Vivian; Kirsanow, Karola; Cassidy, Lara M; Martiniano, Rui; Strobel, Melanie; Scheu, Amelie; Kotsakis, Kostas; Halstead, Paul; Triantaphyllou, Sevi; Kyparissi-Apostolika, Nina; Urem-Kotsou, Dushka; Ziota, Christina; Adaktylou, Fotini; Gopalan, Shyamalika; Bobo, Dean M; Winkelbach, Laura; Blöcher, Jens; Unterländer, Martina; Leuenberger, Christoph; Çilingiroğlu, Çiler; Horejs, Barbara; Gerritsen, Fokke; Shennan, Stephen J; Bradley, Daniel G; Currat, Mathias; Veeramah, Krishna R; Wegmann, Daniel; Thomas, Mark G; Papageorgopoulou, Christina; Burger, Joachim

    2016-06-21

    Farming and sedentism first appeared in southwestern Asia during the early Holocene and later spread to neighboring regions, including Europe, along multiple dispersal routes. Conspicuous uncertainties remain about the relative roles of migration, cultural diffusion, and admixture with local foragers in the early Neolithization of Europe. Here we present paleogenomic data for five Neolithic individuals from northern Greece and northwestern Turkey spanning the time and region of the earliest spread of farming into Europe. We use a novel approach to recalibrate raw reads and call genotypes from ancient DNA and observe striking genetic similarity both among Aegean early farmers and with those from across Europe. Our study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia.

  16. Early farmers from across Europe directly descended from Neolithic Aegeans

    PubMed Central

    Hofmanová, Zuzana; Kreutzer, Susanne; Hellenthal, Garrett; Sell, Christian; Diekmann, Yoan; Díez-del-Molino, David; van Dorp, Lucy; López, Saioa; Kousathanas, Athanasios; Link, Vivian; Kirsanow, Karola; Cassidy, Lara M.; Martiniano, Rui; Strobel, Melanie; Scheu, Amelie; Kotsakis, Kostas; Halstead, Paul; Triantaphyllou, Sevi; Kyparissi-Apostolika, Nina; Ziota, Christina; Adaktylou, Fotini; Gopalan, Shyamalika; Bobo, Dean M.; Winkelbach, Laura; Blöcher, Jens; Unterländer, Martina; Leuenberger, Christoph; Çilingiroğlu, Çiler; Horejs, Barbara; Gerritsen, Fokke; Shennan, Stephen J.; Bradley, Daniel G.; Currat, Mathias; Veeramah, Krishna R.; Thomas, Mark G.; Papageorgopoulou, Christina; Burger, Joachim

    2016-01-01

    Farming and sedentism first appeared in southwestern Asia during the early Holocene and later spread to neighboring regions, including Europe, along multiple dispersal routes. Conspicuous uncertainties remain about the relative roles of migration, cultural diffusion, and admixture with local foragers in the early Neolithization of Europe. Here we present paleogenomic data for five Neolithic individuals from northern Greece and northwestern Turkey spanning the time and region of the earliest spread of farming into Europe. We use a novel approach to recalibrate raw reads and call genotypes from ancient DNA and observe striking genetic similarity both among Aegean early farmers and with those from across Europe. Our study demonstrates a direct genetic link between Mediterranean and Central European early farmers and those of Greece and Anatolia, extending the European Neolithic migratory chain all the way back to southwestern Asia. PMID:27274049

  17. Source mechanism of the 2014 Aegean Sea earthquake

    NASA Astrophysics Data System (ADS)

    Nakano, Masaru

    2016-04-01

    Rapid determination of centroid moment tensor (CMT) of earthquakes, namely the source centroid location, focal mechanism, and magnitude is important for early disaster responses and issuing Tsunami warnings. In order to evaluate capability of Turkey seismic network for rapid determinations of CMT, I investigate the source mechanism of the 2014 Aegean Sea earthquake (Mw 6.9). Although this event occur out of Turkey seismic network, I obtained stable CMT solution. The CMT solution of this earthquake represents a strike-slip fault, consistent with the geometry of the North Anatolian Fault (NAF), and the source-time function indicates that this event comprised several distinct subevents. Each subevent is considered to have ruptured a different fault segment. This observation indicates the existence of a mechanical barrier, namely a NAF segment boundary, at the hypocenter. I also determined CMT solutions of background seismicity. CMT solutions of background seismicity beneath the Aegean Sea represent strike-slip or normal faulting along the NAF or its branch faults. The tensional axes of these events are oriented northeast-southwest, indicating a transtensional tectonic regime. Beneath the Sea of Marmara, the CMT solutions represent mostly strike-slip faulting, consistent with the motion of the NAF, but we identified a normal fault event with a tensional axis parallel to the strike of the NAF. This mechanism indicates that a pull-apart basin, marking a segment boundary of the NAF, is developing there. Because ruptures of a fault system and large earthquake magnitudes are strongly controlled by the fault system geometry and fault length, mapping fault segments along NAF can help to improve the accuracy of scenarios developed for future disastrous earthquakes in the Marmara region.

  18. Old stories and lost pieces of the Eastern Mediterranean puzzle: a new approach to the tectonic evolution of the Western Anatolia and the Aegean Sea

    NASA Astrophysics Data System (ADS)

    Yaltırak, Cenk; Engin Aksu, Ali; Hall, Jeremy; Elitez, İrem

    2015-04-01

    During the last 20 or so years, the tectonic evolution of Aegean Sea and Western Anatolia has been dominantly explained by back-arc extension and escape tectonics along the North Anatolian Fault. Various datasets have been considered in the construction of general tectonic models, including the geometry of fault patterns, paleomagnetic data, extensional directions of the core complexes, characteristic changes in magmatism and volcanism, the different sense of Miocene rotation between the opposite sides of the Aegean Sea, and the stratigraphy and position of the Miocene and Pliocene-Quaternary basins. In these models, the roles of the Burdur-Fethiye Shear Zone, the Trakya-Eskişehir Fault Zone, the Anaximander Mountains and Isparta Angle have almost never been taken into consideration. The holistic evaluation of numerous land and marine researches in the Aegean Sea and western Anatolia suggest the following evolutionary stages: 1. during the early Miocene, Greece and western Anatolia were deformed under the NE-SW extensional tectonics associated with the back-arc extension, when core complexes and supra-detachment basins developed, 2. following the collision of the Anaximander Mountains and western Anatolia in early Miocene , the Isparta Angle locked this side of the western arc by generating a triangle-shaped compressional structure, 3. while the Isparta Angle penetrated into the Anatolia, the NE-striking Burdur-Fethiye Shear Zone in the west and NW-striking Trakya-Eskişehir Fault Zone in the north developed along the paleo-tectonic zones , 4. the formation of these two tectonic structures allowed the counterclockwise rotation of the western Anatolia in the middle Miocene and this rotation removed the effect of the back-arc extension on the western Anatolian Block, 5. the counterclockwise rotation developed with the early westward escape of the Western Anatolian reached up to 35-40o and Trakya-Eskişehir Fault Zone created a total dextral displacement of about 200

  19. A portable and affordable extensional rheometer for field testing

    NASA Astrophysics Data System (ADS)

    Hallmark, Bart; Bryan, Matthew; Bosson, Ed; Butler, Simon; Hoier, Tom; Magens, Ole; Pistre, Nicolas; Pratt, Lee; Ward, Betsy-Ann; Wibberley, Sam; Wilson, D. Ian

    2016-12-01

    Extensional shear testing is often needed to characterise the behaviour of complex fluids found in industry and nature. Traditional extensional rheometers are typically expensive, fragile and heavy and are only suited to making measurements in a laboratory environment. For some applications, it is necessary to make in situ rheological measurements where, for example, fluid properties change rapidly over time or where laboratory facilities are unavailable. This paper reports the development and validation of an inexpensive, lightweight and robust ‘open source’ extensional rheometer, Seymour II. Validation was carried out experimentally and computationally. Measurements on a Newtonian fluid (492 mPa s Brookfield silicone oil) yielded results of 510  ±  51 mPa s; these are comfortably within the range of  ±10% which other authors have quoted for extensional techniques using laboratory rheometers. Comparison of the observed filament thinning dynamics to those obtained using computational fluid dynamics (CFD) gave good qualitative agreement. Use of Seymour II at the University of Cambridge Botanic Gardens revealed that the mucilage of the ‘crane flower’, Strelitzia reginae, was a viscoelastic fluid whose extensional response could be described by a two-mode Giesekus equation. Engineering drawings and image analysis code for Seymour II are available for download at the project website, www.seymourII.org/.

  20. Mixed Layer Depth in the Aegean, Marmara, Black and Azov Seas: Part II: Relation to the Sonic Layer Depth

    DTIC Science & Technology

    2009-03-03

    r.com/ locate / jmarsysMixed layer depth in the Aegean, Marmara, Black and Azov Seas : Part II: Relation to the sonic layer depth Robert W. Helber a...index terms: The Aegean Sea The Black Sea The Azov Sea Keywords: Sound transmission Mixed layer depth Climatologyt analysis of the seasonal evolution of...the sonic layer depth (SLD) relative to the mixed layer depth (MLD) for the Aegean, Marmara, Black, and Azov Seas . SLD identifies the acoustic ducting

  1. The role of extensional viscosity in frog tongue projection

    NASA Astrophysics Data System (ADS)

    Noel, Alexis; Wagner, Caroline; McKinley, Gareth; Mendelson, Joe; Hu, David

    2014-11-01

    Frogs and other amphibians capture insects through high-speed tongue projection, some achieving tongue accelerations of over fifty times gravity. In this experimental study, we investigate how a frog's sticky saliva enables high-speed prey capture. At the Atlanta zoo, we used high-speed video to film the trajectory of frog tongues during prey capture. We have also designed and built a portable extensional rheometer; by following the capillary-driven thinning in the diameter of a thread of saliva we characterize the relaxation time and extensional viscosity and so infer the adhesive force between the frog tongue and prey.

  2. Static Stress Changes Inverted from Microseismicity in Eastern Aegean Sea

    NASA Astrophysics Data System (ADS)

    Leptokaropoulos, Konstantinos; Papadimitriou, Eleftheria; Orlecka-Sikora, Beata; Karakostas, Vassilios

    2014-05-01

    In this study we attempted to derive static stress field variations from the changes of earthquake production rates in Kusadasi bay and Samos island (eastern Aegean), by applying the Dieterich et al. (2000) Rate/State formulation. The calculation of stress changes from earthquake occurrence rates fluctuations should be obtained from catalogues which achieve adequate spatial and temporal resolution and well determined hypocenter coordinates. For this reason we took advantage of the data from a regional network operating since July of 2007, providing continuous monitoring of microseismicity, along with data available from seismological stations of the permanent Hellenic Unified Seismological Network (HUSN). The high accuracy and large sized regional catalogue is utilized for inverting seismicity rate changes into stress variation through a Rate/State dependent friction model. After explicitly determining the physical parameters incorporating in the modeling (reference seismicity rates, characteristic relaxation time, constitutive properties of fault zones) we investigated stress changes in both space and time regime and their possible connection with earthquake clustering and fault interactions. The main interest is focused on the June 2009 Samos Mw=5.1 event, which was followed by an intense seismic activity for several days. We attempt to reproduce and interpret stress changes both before and after the initiation of this seismic burst. The differences between the earthquake occurrence rates before and after the main shock are used as input data in a stress inversion algorithm based upon the Rate/State dependent friction concept in order to provide an estimation of stress changes. Diverse assumptions and combinations of the parameters values are tested for the model performance and sensitivity to be evaluated. The approach followed here could provide evidence of the robustness of the seismicity rate changes usage as a stress meter for both positive and negative

  3. What sets topographic relief in extensional footwalls?

    NASA Astrophysics Data System (ADS)

    Densmore, Alexander L.; Dawers, Nancye H.; Gupta, Sanjeev; Guidon, Roman

    2005-06-01

    We use three large normal fault arrays in the northeastern Basin and Range Province, western United States, to document catchment development and relief production during fault growth. Fault slip and slip rates increase systematically along strike from zero at the fault tips. Catchment relief and across-strike range width both increase as slip accumulates but reach maximum values at a distance of ˜15 km from the fault tips and remain uniform along strike over much of the footwalls. Catchment outlet spacing also increases away from the fault tips but does not reach a uniform value and may vary by a factor of 5 6 along strike. We infer that catchments first elongate in the across-strike direction as slip accumulates and the range half-width increases. Once the half-width reaches its maximum value, continued catchment growth is possible only by along-strike capture, which increases outlet spacing but not relief. The close correspondence between catchment relief and range half-width suggests that geomorphically limited hillslope and channel gradients are achieved within the 15 km tip zone. Thus, the limiting factor in footwall development is the width of the range, which is controlled by two external agents: the geometry and spacing of the major faults, and the elevations of base level on both flanks.

  4. Factors That Influence the Extensional Rheological Property of Saliva

    PubMed Central

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva. PMID:26305698

  5. The extensional rheology of non-Newtonian materials

    NASA Technical Reports Server (NTRS)

    Spiegelberg, Stephen H.; Gaudet, Samuel; Mckinley, Gareth H.

    1994-01-01

    It has been proposed to measure the extensional viscosity function of a non-Newtonian polymer solution in a reduced gravity environment as part of the Advanced Fluid Module. In ground-based extensional measurements, the no-sip boundary condition at solid-fluid interfaces always result in appreciable shear gradients in the test fluid; however the removal of gravitational body forces permits controlled extensional deformation of containerless test samples and the first unambiguous measurements of this kind. Imperative to successful implementation of this experiment is the generation and subsequent deformation of a stable cylindrical column of test fluid. A study of the generation and deformation of liquid bridges demonstrates that Newtonian liquid bridges undergo capillary breakup as anticipated when stretched beyond a critical aspect ratio; non-Newtonian liquid bridges, however, are stabilized by the strain-hardening phenomenon exhibited by these materials. Numerical simulations of Newtonian breakup are compared with experimental results, and show that previous ground-based attempts at measuring the extensional viscosity of Newtonian fluids are of limited accuracy.

  6. Naive Probability: A Mental Model Theory of Extensional Reasoning.

    ERIC Educational Resources Information Center

    Johnson-Laird, P. N.; Legrenzi, Paolo; Girotto, Vittorio; Legrenzi, Maria Sonino; Caverni, Jean-Paul

    1999-01-01

    Outlines a theory of naive probability in which individuals who are unfamiliar with the probability calculus can infer the probabilities of events in an "extensional" way. The theory accommodates reasoning based on numerical premises, and explains how naive reasoners can infer posterior probabilities without relying on Bayes's theorem.…

  7. Factors That Influence the Extensional Rheological Property of Saliva.

    PubMed

    Vijay, Amrita; Inui, Taichi; Dodds, Michael; Proctor, Gordon; Carpenter, Guy

    2015-01-01

    The spinnbarkeit of saliva reflects the ability of saliva to adhere to surfaces within the mouth, thereby serving as a protective role and aiding in lubrication. Therefore, alterations in the extensional rheology of saliva may result in the loss in adhesiveness or the ability to bind onto surfaces. Mucin glycoproteins and their structures are known to be important factors for the extensional rheological properties of saliva. The conformation of mucin depends on factors such as pH and ionic strength. Chewing is one of the main stimuli for salivary secretion but creates significant sheer stress on the salivary film which could influence mouthfeel perceptions. The current study investigates the possible factors which affect the extensional rheological properties of saliva by comparing submandibular/sublingual saliva with different oral stimuli within the same group of subjects. Unstimulated and stimulated saliva (chew, smell and taste) salivas were collected primarily from submandibular/sublingual glands. The saliva samples were measured for Spinnbarkeit followed by the measuring mucin, total protein, total calcium and bicarbonate concentrations. The results indicated correlations between rheological properties and mucin/ion concentrations. However, chewing stimulated submandibular/sublingual saliva is shown to have significantly lower Spinnbarkeit, but factors such as mucin, protein and calcium concentrations did not account for this variation. Analysis of the concentration of bicarbonate and pH appears to suggest that it has a prominent effect on extensional rheology of saliva.

  8. Strain Localization Within a Syn-Tectonic Pluton in a Back-Arc Extensional Context: the Naxos granodiorite (Cyclades, Greece)

    NASA Astrophysics Data System (ADS)

    Bessiere, Eloïse; Rabillard, Aurélien; Arbaret, Laurent; Jolivet, Laurent; Augier, Romain; Menant, Armel

    2016-04-01

    Naxos Island is part of the central Cyclades (Aegean Sea, Greece) where a series of migmatite-cored metamorphic domes were exhumed below large-scale detachment systems during a Cenozoic back-arc extension. On Naxos, the Miocene exhumation history of the high-temperature metamorphic dome was notably achieved through two anastomosing and closely spaced top-to-the-north detachments belonging to the Naxos-Paros detachment system. According to previous contributions, the late exhumation stages were accompanied by the emplacement of a syn-kinematic I-type granodiorite that intruded a ductile-then-brittle detachment. Later the detachment migrated at the interface between the pluton and the metamorphic unit under ductile-to-brittle conditions. To clarify how extensional deformation was precisely distributed within the pluton, a multi-scale approach from field observations to laboratory investigations was undertaken. Through macro- to micro-structural observations, we show a continuous deformation history from magmatic to solid-state ductile/brittle conditions under an overall north-directed shearing deformation. The early magmatic or sub-solidus deformation is evidenced in a large part of the granodiorite, notably in its southern part where the original intrusive contact is still preserved. Solid-state deformation is recorded further north when approaching the detachment zone, highlighted by a thicker cataclastic zone and numerous pseudotachylite veins. From these field observations, we defined six strain facies, leading us to propose a qualitative strain map of the Naxos granodiorite. Based on field pictures and X-ray tomography of oriented samples collected along the strain gradient, we quantified the intensity of mineralogical fabrics in 2D and 3D. This step required the treatment of 600 rocks samples and pictures using SPO2003 (Shape Preferred Orientation) and Intercepts2003. Measured shape variations of the strain ellipsoid thus corroborate the large-scale strain

  9. Upper Cenozoic organic-rich sequences (offshore and onshore the south Aegean sea)

    SciTech Connect

    Anastasakis, G.

    1988-08-01

    The upper Cenozoic sedimentary column of the south Aegean Sea is composed mostly of marine sediments which have been deposited after the Seravallian breakup of the south Aegean landmass. Extensive submarine coring has revealed the frequent occurrence of Quaternary dark, organic-rich layers in the cores retrieved from water depths greater than 180 m. Moreover, deep-sea drilling (DSDP leg 42A) in the south Aegean basin recovered organic-rich layers as old as late Miocene. Onshore the south Aegean Sea islands, organic-rich sediments are found at the north and south territories of the region, on Milos and Crete islands. Especially on the island of Crete and south of it, on the smaller islands of Gavdos and Koufonisi, these organic-rich sediments represent a considerable portion of the widespread upper Cenozoic sediments. Stratigraphically they cover the interval between upper Seravallian and lower Pleistocene. The organic carbon content of all these mostly calcareous lithofacies, the so-called sapropels, ranges mostly between 0.5 and 6.5%. The most reliably chronostratigraphically correlated upper Pleistocene sapropels display similar compositional characteristics across the entire basin. Certain Pleistocene and older organic-rich layers contain increased proportions of siliceous tests. However the entire range of sapropels in the region (except those within the Messinian evaporites) can be described adequately by the same lithofacies association. To demonstrate this the authors compare the lower Tortonian Faneromeni Formation on Crete with the upper Quaternary sediments from the south Aegean Sea.

  10. Chronology for the Aegean Late Bronze Age 1700-1400 B.C.

    PubMed

    Manning, Sturt W; Ramsey, Christopher Bronk; Kutschera, Walter; Higham, Thomas; Kromer, Bernd; Steier, Peter; Wild, Eva M

    2006-04-28

    Radiocarbon (carbon-14) data from the Aegean Bronze Age 1700-1400 B.C. show that the Santorini (Thera) eruption must have occurred in the late 17th century B.C. By using carbon-14 dates from the surrounding region, cultural phases, and Bayesian statistical analysis, we established a chronology for the initial Aegean Late Bronze Age cultural phases (Late Minoan IA, IB, and II). This chronology contrasts with conventional archaeological dates and cultural synthesis: stretching out the Late Minoan IA, IB, and II phases by approximately 100 years and requiring reassessment of standard interpretations of associations between the Egyptian and Near Eastern historical dates and phases and those in the Aegean and Cyprus in the mid-second millennium B.C.

  11. Tsunami Propagation Database for the Mediterranean and Aegean Seas

    NASA Astrophysics Data System (ADS)

    Kanoglu, U.; Hoto, O.; Kalligeris, N.; Flouri, E.; Aydin, B.; Moore, C. W.; Synolakis, C. E.

    2012-12-01

    Pre-computed tsunami scenario databases are common tools to develop long- or short-term forecasting methodologies and hazard assessment approaches for tsunami-prone regions worldwide. The benefits of such databases include the possibility of probabilistic studies (Gonzalez et al., 2009, J. Geophys. Res. 114, Article Number: C11023), inundation mapping (Barberopoulou et al., 2011, Pure Appl. Geophys. 168(11), 2133-2146), or real-time forecasting (Wei et al., 2008, Geophys. Res. Lett. 35(4), Article Number: L04609). As a result, several tsunami propagation databases have been developed including one by NOAA's Pacific Marine Environmental Laboratory (PMEL), and another by the Australian Bureau of Meteorology (BOM). Pre-computed tsunami scenario databases utilize different approaches. PMEL's tsunami propagation database is based on the concept of a pre-computed tsunami scenarios consisting of propagation results from 100km x 50km fault planes with a slip value of 1m referred to as tsunami source functions. PMEL's source functions are placed along the subduction zones in several rows, covering known faults throughout the major ocean basins. Linearity of the tsunami propagation in the open ocean allows scaling and/or combination of the pre-computed tsunami source functions to generate a desired scenario. The BOM database considers five earthquakes with magnitudes changing from 7.0 to 9.0 at each location with 100km intervals along the subduction zone. However, to date, no similar approach has been computed along the subduction zones in the Aegean and Mediterranean Seas, even though, historically, there have been a considerable number of tsunami events which caused damage in the region (Ambraseys and Synolakis, 2010, J. Earthquake Eng. 14 (3), 309-330, Article Number: PII 919600673). A new project was initiated between Greece and Turkey supported by General Secretariat for Research & Technology, The Ministry for Development (GSRT) of Greece and The Scientific and

  12. Teleconnections, Midlatitude Cyclones and Aegean Sea Turbulent Heat Flux Variability on Daily Through Decadal Time Scales

    NASA Technical Reports Server (NTRS)

    Romanski, Joy; Romanou, Anastasia; Bauer, Michael; Tselioudis, George

    2013-01-01

    We analyze daily wintertime cyclone variability in the central and eastern Mediterranean during 1958-2001, and identify four distinct cyclone states, corresponding to the presence or absence of cyclones in each basin. Each cyclone state is associated with wind flows that induce characteristic patterns of cooling via turbulent (sensible and latent) heat fluxes in the eastern Mediterranean basin and Aegean Sea. The relative frequency of occurrence of each state determines the heat loss from the Aegean Sea during that winter, with largest heat losses occurring when there is a storm in the eastern but not central Mediterranean (eNOTc), and the smallest occurring when there is a storm in the central but not eastern Mediterranean (cNOTe). Time series of daily cyclone states for each winter allow us to infer Aegean Sea cooling for winters prior to 1985, the earliest year for which we have daily heat flux observations. We show that cyclone states conducive to Aegean Sea convection occurred in 1991/1992 and 1992/1993, the winters during which deep water formation was observed in the Aegean Sea, and also during the mid-1970s and the winters of 1963/1964 and 1968/1969. We find that the eNOTc cyclone state is anticorrelated with the North Atlantic Oscillation (NAO) prior to 1977/1978. After 1977/1978, the cNOTe state is anticorrelated with both the NAO and the North Caspian Pattern (NCP), showing that the area of influence of large scale atmospheric teleconnections on regional cyclone activity shifted from the eastern to the central Mediterranean during the late 1970s. A trend toward more frequent occurrence of the positive phase of the NAO produced less frequent cNOTe states since the late 1970s, increasing the number of days with strong cooling of the Aegean Sea surface waters.

  13. Mixed Layer Depth in the Aegean, Marmara, Black and Azov Seas: Part I: General Features

    DTIC Science & Technology

    2009-02-28

    r.com/ locate / jmarsysMixed layer depth in the Aegean, Marmara, Black and Azov Seas : Part I: General features A. Birol Kara a,⁎, Robert W. Helber a...suffer from lack of input T and S profiles in the Marmara and Azov Seas , thus they may not be representative.MonthlyMLDfields presented in this paper are...Boyer), .V.there has been no study which describes seasonal characteristics of MLD in the Aegean, Marmara, Black and Azov Seas , whose bottom

  14. Exhumation and cooling of the Serifos metamorphic core complex, western Cyclades: extensional surging or continuum since the Early Oligocene?

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Schneider, D. A.; Grasemann, B.; Iglseder, Ch.; Stöckli, D.; Heizler, M.

    2009-04-01

    The western Cycladic island of Serifos lies within the active tectonic setting of the Aegean region where southward retreat of the subducting Hellenic slab and associated back-arc crustal block rotation has led to progressive extensional collapse of the lithosphere. Widespread exhumation has regionally exposed mid-crustal metamorphic and plutonic rocks through low-angle detachments associated with metamorphic core complex development. On Serifos, bedrock lithologies consisting of calc-silicates, schists, gneisses, and marbles metamorphosed under greenschist- to lower amphibolite- facies conditions are intruded by a largely undeformed, Late Miocene I-type granodiorite pluton that dominates the southeast portion of the metamorphic dome. Project ACCEL (Aegean Core Complexes along an Extended Lithosphere) documented that this pluton crosscuts a crustal-scale anastomosing shear zone consisting of (ultra) mylonitic marbles and orthogneisses that record consistent SSW-directed shear. These intensely sheared orthogneisses, yielding a preliminary U-Pb zircon rim crystallization age of c. 37 Ma, represent an earlier S-type granitoid that syn-kinematically intruded to mid-crustal levels during Late Eocene deformation. Additional thermochronometric constraints presented here elucidate the timing of extension and exhumation of the Serifos metamorphic core complex through mid- to shallow-crustal levels. Moderate temperature constraints from Ar-Ar analysis of white micas reveal two distinct cooling age populations separated by a steep age gradient that is coincident with the high-strain mylonitic shear zone. The micas define the rock's foliation in most cases with notable mica fish from shear zone samples and geochemical analysis via electron microprobe confirms that all micas are of a similar muscovite composition. Micas from southern portions of the island, within the shear zone and adjacent to the granodiorite pluton, yield Late Miocene cooling ages of 8-9 Ma, indicating

  15. Optimized cross-slot flow geometry for microfluidic extensional rheometry.

    PubMed

    Haward, Simon J; Oliveira, Mónica S N; Alves, Manuel A; McKinley, Gareth H

    2012-09-21

    A precision-machined cross-slot flow geometry with a shape that has been optimized by numerical simulation of the fluid kinematics is fabricated and used to measure the extensional viscosity of a dilute polymer solution. Full-field birefringence microscopy is used to monitor the evolution and growth of macromolecular anisotropy along the stagnation point streamline, and we observe the formation of a strong and uniform birefringent strand when the dimensionless flow strength exceeds a critical Weissenberg number Wi(crit) ≈ 0.5. Birefringence and bulk pressure drop measurements provide self-consistent estimates of the planar extensional viscosity of the fluid over a wide range of deformation rates (26 s(-1) ≤ ε ≤ 435 s(-1)) and are also in close agreement with numerical simulations performed by using a finitely extensible nonlinear elastic dumbbell model.

  16. Development and modeling of novel extensional ionic polymer transducers

    NASA Astrophysics Data System (ADS)

    Akle, Barbar; Wallmersperger, Thomas; Leo, Donald

    2007-04-01

    Ionic polymer transducers (IPT), sometimes referred to as artificial muscles, are known to generate a large bending strain and a moderate stress at low applied voltages. Bending actuators have limited engineering applications due to the low forcing capabilities and the need for complicated external devices to convert the bending action into rotating or linear motion desired in most devices. Recently Akle and Leo (2006) reported extensional actuation in ionic polymer transducers. Model prediction indicates that such actuators can produce strain up to 10% and a blocked stress up to 20MPa under a +/- 2V applied electric potential. Compared to other smart materials, IPT is a flexible membrane and it has a reliability of over one million cycles. In this work novel extensional IPT actuators are developed for the purpose of increasing the overall displacement of the actuator. The electromechanical coupling is measured and a correlation of the experimental data with the active areas model by Akle and Leo (2006) and the numerical electromechanical model by Wallmersperger and Leo (2004) are presented. The coupling between each test case with the model parameters enables further understanding of the physical actuation phenomena as the role of diffusion of ions and diluents and the electrostatic forces between the charged species. In this study the displacement of an extensional ionic polymer transducer is measured and compared to the bending of the same IPT actuator. The bending strain is measured to be approximately 2.5%, while the extensional strain for the same ionomer is in the order of 17.5%. Finally an interesting behavior, reported for the first time is the steady expansion of the IPT sample due to the application of a symmetrical sine wave. This indicates that charge accumulation is occurring at the electrode.

  17. Subglacial extensional fracture development and implications for Alpine Valley evolution

    NASA Astrophysics Data System (ADS)

    Leith, Kerry; Moore, Jeffrey R.; Amann, Florian; Loew, Simon

    2014-01-01

    stresses induced through exhumation and tectonic processes play a key role in the topographic evolution of alpine valleys. Using a finite difference model combining the effects of tectonics, erosion, and long-term bedrock strength, we assess the development of near-surface in situ stresses and predict bedrock behavior in response to glacial erosion in an Alpine Valley (the Matter Valley, southern Switzerland). Initial stresses are derived from the regional tectonic history, which is characterized by ongoing transtensional or extensional strain throughout exhumation of the brittle crust. We find that bedrock stresses beneath glacial ice in an initial V-shaped topography are sufficient to induce localized extensional fracturing in a zone extending laterally 600 m from the valley axis. The limit of this zone is reflected in the landscape today by a valley "shoulder," separating linear upper mountain slopes from the deep U-shaped inner valley. We propose that this extensional fracture development enhanced glacial quarrying between the valley shoulder and axis and identify a positive feedback where enhanced quarrying promoted valley incision, which in turn increased in situ stress concentrations near the valley floor, assisting erosion and further driving rapid U-shaped valley development. During interglacial periods, these stresses were relieved through brittle strain or topographic modification, and without significant erosion to reach more highly stressed bedrock, subsequent glaciation caused a reduction in differential stress and suppressed extensional fracturing. A combination of stress relief during interglacial periods, and increased ice accumulation rates in highly incised valleys, will reduce the likelihood of repeat enhanced erosion events.

  18. Cluster analysis of indermediate deep events in the southeastern Aegean

    NASA Astrophysics Data System (ADS)

    Ruscic, Marija; Becker, Dirk; Brüstle, Andrea; Meier, Thomas

    2015-04-01

    The Hellenic subduction zone (HSZ) is the seismically most active region in Europe where the oceanic African litosphere is subducting beneath the continental Aegean plate. Although there are numerous studies of seismicity in the HSZ, very few focus on the eastern HSZ and the Wadati-Benioff-Zone of the subducting slab in that part of the HSZ. In order to gain a better understanding of the geodynamic processes in the region a dense local seismic network is required. From September 2005 to March 2007, the temporary seismic network EGELADOS has been deployed covering the entire HSZ. It consisted of 56 onshore and 23 offshore broadband stations with addition of 19 stations from GEOFON, NOA and MedNet to complete the network. Here, we focus on a cluster of intermediate deep seismicity recorded by the EGELADOS network within the subducting African slab in the region of the Nysiros volcano. The cluster consists of 159 events at 80 to 190 km depth with magnitudes between 0.2 and 4.1 that were located using nonlinear location tool NonLinLoc. A double-difference earthquake relocation using the HypoDD software is performed with both manual readings of onset times and differential traveltimes obtained by separate cross correlation of P- and S-waveforms. Single event locations are compared to relative relocations. The event hypocenters fall into a thin zone close to the top of the slab defining its geometry with an accuracy of a few kilometers. At intermediate depth the slab is dipping towards the NW at an angle of about 30°. That means it is dipping steeper than in the western part of the HSZ. The edge of the slab is clearly defined by an abrupt disappearance of intermediate depths seismicity towards the NE. It is found approximately beneath the Turkish coastline. Furthermore, results of a cluster analysis based on the cross correlation of three-component waveforms are shown as a function of frequency and the spatio-temporal migration of the seismic activity is analysed.

  19. Psychiatric Morbidity and Social Capital in Rural Communities of the Greek North Aegean Islands

    ERIC Educational Resources Information Center

    Tseloni, Andromachi; Zissi, Anastasia; Skapinakis, Petros

    2010-01-01

    Which facets of social capital affect mental health in rural settings? This study explores the association between different aspects of social capital and psychiatric morbidity in rural communities of the Greek North Aegean islands. A large number of individual and community characteristics that may influence psychiatric morbidity are concurrently…

  20. Shallow structure and recent evolution of the Aegean Sea deduced from the seismic reflection analysis

    SciTech Connect

    Laure, M.; Mascle, J.

    1988-08-01

    Together with the Tyrrhenian Sea, the Aegean Sea represents one of two marine basins still developing as a consequence of the subduction of the African lithosphere beneath Europe. Despite many geophysical similarities with the Tyrrhenian Sea, the Aegean displays a specific structural segmentation characterized by two distinct domains separated by the central Aegean. To the north of the basin, the so-called North Aegean trough likely represents the western marine extension of the transtensive Anatolian transform fault zone. The northern margin of this area contains a series of disconnected, often thickly sedimented small basins that probably initiated during the late Miocene as a consequence of a dominantly north-south extension; typical uppermost Miocene (Messinian) formations can be observed on seismic grounds. To the south, the Cretan Sea shows clear evidence of important distensive events occurring during two main episodes and following two main trends; a dominantly north-south-directed extension is responsibile for most of the structural features detected along both the Cretan and southern Cyclades margins.

  1. Structure of flows in the Northern Aegean Sea from a pilot drifter array

    NASA Astrophysics Data System (ADS)

    Kourafalou, V.; Olson, D.; Johns, W.; Kontoyiannis, H.; Zervakis, V.

    2003-04-01

    An array of thirty drifters deployed in the northern Aegean are used to consider the circulation in a complex archipelago of islands. The circulation of the Aegean is largely influenced by a combination of buoyancy from freshwaters introduced from the Black Sea via the Dardenelles Straits and from coastal rivers and by wind forcing. The latter is highly structured as the winds along the axis of the Aegean Sea are channeled between the orography of the Greek peninsula and islands. The above mechanisms are revealed in the drifter tracts. Preferred pathways that mark transport and exchange between the northern and southern parts of the basin are also evident. The drifters equipped with hourly GPS location and holly sock drogues provide information of time and space scales that have not been routinely sampled before. After a brief review of the overall circulation outlined by the array, the statistics of the turbulent field and its variation for the various subbasins are described. Of special interest are coastal plumes, motions induced as fluid passes between sub-basins, and the nature of cyclonic flows trapped within deep topographic pockets through the Aegean. An initial comparison of eddy statistics in relationship to wind events is also reported.

  2. Phytoplankton size-based dynamics in the Aegean Sea (Eastern Mediterranean)

    NASA Astrophysics Data System (ADS)

    Ignatiades, L.; Psarra, S.; Zervakis, V.; Pagou, K.; Souvermezoglou, E.; Assimakopoulou, G.; Gotsis-Skretas, O.

    2002-07-01

    This study represents one component of the large MTP-II-MATER (MAST-III) multidisiplinary project in the Mediterranean supported by EU. Data were collected during three cruises performed in Spring and Autumn 1997 and Spring 1998 from six stations of the North and five stations of the South Aegean Sea. The work assessed the spatial, vertical and temporal variations of size fractionated chlorophyll α, primary production (in situ), photosynthetic parameters (in situ) and the taxonomic composition of phytoplankton. The population structure and dynamics were greatly influenced by the different hydrographic conditions prevailing in the Northern and Southern Aegean Sea due to the influence of Black Sea and Levantine Sea waters, respectively. The picoplankton fraction (0.2-1.2 μm) predominated and accounted for the 56% to 49% of total chl α and the 51% to 41% of total primary production in the N. and S. Aegean Sea, respectively. Throughout the sampling area, the levels of nano+microplankton (>3.0 μm) were next in abundance proportions of total chl α (21-31%) and primary production (20-33%) and the levels of the ultraplankton (1.2-3.0 μm) were the lowest, contributing the 18-22% of total chl α and the 20-23% of total primary production. There was a highly significant ( P≤0.005-0.01) spatial, vertical and temporal influence on the biomass and productivity of all size classes in the N. Aegean and of most of them in S. Aegean. Light utilization efficiency ( ɛ%) and quantum yield ( ϕmax) exhibited a temporal trend having higher values in Spring than in Autumn as well as a trend affected by cell size, being higher for picoplankton in relation to ultraplankton and nano+microplankton. Assimilation ratios ( PB) increased with cell size. Daily primary production in the N. Aegean (81.36 mg C m -2 day -1) was higher than that in the S. Aegean (38.88 mg C m -2 day -1) but both are characterized as the most oligotrophic areas of the eastern Mediterranean.

  3. Plant speciation in continental island floras as exemplified by Nigella in the Aegean Archipelago.

    PubMed

    Comes, Hans Peter; Tribsch, Andreas; Bittkau, Christiane

    2008-09-27

    Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of geographical isolation on non-adaptive radiation and allopatric speciation brought about by genetic drift. The Aegean Archipelago forms a highly fragmented complex of mostly continental shelf islands that have become disconnected from each other and the mainland in relatively recent geological times (ca <5.2 Ma). These ecologically fairly homogenous islands thus provide a suitable biogeographic context for assessing the relative influences of past range fragmentation, colonization, gene flow and drift on taxon diversification. Indeed, recent molecular biogeographic studies on the Aegean Nigella arvensis complex, combining phylogenetic, phylogeographic and population level approaches, exemplify the importance of allopatry and genetic drift coupled with restricted gene flow in driving plant speciation in this continental archipelago at different temporal and spatial scales. While the recent (Late Pleistocene) radiation of Aegean Nigella, as well as possible instances of incipient speciation (in the Cyclades), is shown to be strongly conditioned by (palaeo)geographic factors (including changes in sea level), shifts in breeding system (selfing) and associated isolating mechanisms have also contributed to this radiation. By contrast, founder event speciation has probably played only a minor role, perhaps reflecting a migratory situation typical for continental archipelagos characterized by niche pre-emption because of a long established resident flora. Overall, surveys of neutral molecular markers in Aegean Nigella have so far revealed population genetic processes that conform remarkably well to predictions raised by genetic drift theory. The challenge is now to gain more direct insights into the relative importance of the role of genetic drift, as opposed to natural selection, in the phenotypic and reproductive divergence among these Aegean plant

  4. Anelastic attenuation structure of the southern Aegean subduction area

    NASA Astrophysics Data System (ADS)

    Ventouzi, Chrisanthi; Papazachos, Constantinos; Papaioannou, Christos; Hatzidimitriou, Panagiotis

    2014-05-01

    The study of the anelastic attenuation structure plays a very important role for seismic wave propagation and provides not only valuable constraints for the Earth's interior (temperature, relative viscosity, slab dehydration and melt transport) but also significant information for the simulation of strong ground motions. In order to investigate the attenuation structure of the broader Southern Aegean subduction area, acceleration spectra of intermediate depth earthquakes produced from data provided by two local networks which operated in the area were used. More specifically, we employed data from approximately 400 intermediate-depth earthquakes, as these were recorded from the EGELADOS seismic monitoring project which consisted of 65 land stations and 24 OBS recorders and operated during 2005-2007, as well as data from the earlier installed CYCNET local network, which operated during 2002-2005. A frequency-independent path attenuation operator t* was computed for both P and S arrivals for each waveform, using amplitude spectra generated by the recorded data of the aforementioned networks. Initially, estimated P and S traveltimes were examined and modeled as a function of epicentral distance for different groups of focal depths, using data from the CYCNET network in order to obtain the expected arrival information when original arrival times were not available. Two approaches to assess the spectral-decay were adopted for t* determination. Initially, an automated approach was used, where t* was automatically calculated from the slope of the acceleration spectrum, assuming an ω2 source model for frequencies above the corner frequency, fc. Estimation of t* was performed in the frequency band of 0.2 to 25 Hz, using only spectra with a signal-to-noise ratio larger than 3 for a frequency range of at least 4Hz for P-waves and 1Hz for S-waves, respectively. In the second approach, the selection of the linearly-decaying part of the spectra where t* was calculated, was

  5. Modes of tilting during extensional core complex development.

    PubMed

    Coleman, D S; Walker, J D

    1994-01-14

    Crustal extension and formation of the Mineral Mountains core complex, Utah, involved tilting of the Mineral Mountains batholith and associated faults during hanging wall and footwall deformation. The batholith was folded in the hanging wall of the Beaver Valley fault between 11 and 9 million years ago yielding about 45 degrees of tilt. Subsequently, the batholith was unroofed along the Cave Canyon detachment fault, and the batholith and fault were tilted approximately 40 degrees during footwall uplift. Recognition of deformed dikes beneath the detachment fault establishes the importance of footwall tilt during formation of extensional core complexes and demonstrates that footwall rebound can be an important process during extension.

  6. Suturing and extensional reactivation in the Grenville orogen, Canada

    NASA Astrophysics Data System (ADS)

    Busch, Jay P.; Mezger, Klaus; van der Pluijm, Ben A.

    1997-06-01

    Sutures are zones of weakness within orogenic belts that have the potential to become reactivated during orogenic evolution. The Robertson Lake shear zone marks a major tectonic boundary in the southeastern Grenville orogen of Canada that has been intermittently active for at least 130 m.y. The shear zone played a major role in the compressional stage of the orogenic cycle as well as during postorogenic collapse. The zone separates the Elzevir terrane to the west and the Frontenac terrane to the east. Sphene ages (U-Pb) indicate that these two terranes have distinct tectonothermal histories and that the shear zone represents a “cryptic suture.” In its current state, the shear zone is a low angle (30°ESE dip) plastic to brittle extensional shear zone that separates the Mazinaw (footwall) and Sharbot Lake (hanging wall) domains. Integration of structural, metamorphic, and chronologic data leads to a model that describes the complete evolution of this fundamental tectonic boundary that evolved from an early compressional zone (ca. 1030 Ma) to a late extensional zone (until at least 900 Ma).

  7. Numerical analysis of strongly nonlinear extensional vibrations in elastic rods.

    PubMed

    Vanhille, Christian; Campos-Pozuelo, Cleofé

    2007-01-01

    In the framework of transduction, nondestructive testing, and nonlinear acoustic characterization, this article presents the analysis of strongly nonlinear vibrations by means of an original numerical algorithm. In acoustic and transducer applications in extreme working conditions, such as the ones induced by the generation of high-power ultrasound, the analysis of nonlinear ultrasonic vibrations is fundamental. Also, the excitation and analysis of nonlinear vibrations is an emergent technique in nonlinear characterization for damage detection. A third-order evolution equation is derived and numerically solved for extensional waves in isotropic dissipative media. A nine-constant theory of elasticity for isotropic solids is constructed, and the nonlinearity parameters corresponding to extensional waves are proposed. The nonlinear differential equation is solved by using a new numerical algorithm working in the time domain. The finite-difference numerical method proposed is implicit and only requires the solution of a linear set of equations at each time step. The model allows the analysis of strongly nonlinear, one-dimensional vibrations and can be used for prediction as well as characterization. Vibration waveforms are calculated at different points, and results are compared for different excitation levels and boundary conditions. Amplitude distributions along the rod axis for every harmonic component also are evaluated. Special attention is given to the study of high-amplitude damping of vibrations by means of several simulations. Simulations are performed for amplitudes ranging from linear to nonlinear and weak shock.

  8. Determination of Extensional Rheological Properties by Hyperbolic Contraction Flow

    NASA Astrophysics Data System (ADS)

    Stading, Mats

    2008-07-01

    Extensional rheologyy is important for diverse applications such as processing of viscoelastic fluids, mouthfeel of semi-solid foods, cell mitosis and baking, and is also a useful tool for testing the applicability of constitutive equations. Despite the documented influence of extensional rheological properties, it is seldom measured due to experimental difficulties. There are only commercial equipments available for low-viscosity fluids by Capillary Breakup and for polymer melts by Meissner-type winding of ribbons around cylinders. Both methods have limited applicability for medium-viscosity fluids such as foods and other biological systems. Contraction flows are extensively studied and a new test method has been developed based on contraction flow through a hyperbolic nozzle. The method is suitable for medium-viscosity fluids and has been validated by comparison to results from Filament Stretching and Capillary Breakup. The hyperbolic contraction flow method has been used to characterize food and medical systems, distinguish between different products having equal shear behavior, quantify ropy mouth feel and to predict foaming behavior of biopolymers.

  9. Folding associated with extensional faulting: Sheep Range detachment, southern Nevada

    SciTech Connect

    Guth, P.L.

    1985-01-01

    The Sheep Range detachment is a major Miocene extensional fault system of the Great Basin. Its major faults have a scoop shape, with straight, N-S traces extending 15-30 km and then abruptly turning to strike E-W. Tertiary deformation involved simultaneous normal faulting, sedimentation, landsliding, and strike-slip faulting. Folds occur in two settings: landslide blocks and drag along major faults. Folds occur in landslide blocks and beneath them. Most folds within landslide blocks are tight anticlines, with limbs dipping 40-60 degrees. Brecciation of the folds and landslide blocks suggests brittle deformation. Near Quijinump Canyon in the Sheep Range, at least three landslide blocks (up to 500 by 1500 m) slid into a small Tertiary basin. Tertiary limestone beneath the Paleozoic blocks was isoclinally folded. Westward dips reveal drag folds along major normal faults, as regional dips are consistently to the east. The Chowderhead anticline is the largest drag fold, along an extensional fault that offsets Ordovician units 8 km. East-dipping Ordovician and Silurian rocks in the Desert Range form the hanging wall. East-dipping Cambrian and Ordovician units in the East Desert Range form the foot wall and east limb of the anticline. Caught along the fault plane, the anticline's west-dipping west limb contains mostly Cambrian units.

  10. An isostatic model for the Tharsis province, Mars

    NASA Technical Reports Server (NTRS)

    Sleep, N. H.; Phillips, R. J.

    1979-01-01

    A crust-upper mantle configuration is proposed for the Tharsis province of Mars which is isostatic and satisfies the observed gravity data. The model is that of a low density upper mantle compensating loads at both the surface and crust-mantle boundary. Solutions are found for lithospheric thickness greater than about 300 km, for which the stress differences are less than 750 bars. This model for Tharsis is similar to the compensation mechanism under the Basin and Range province of the western United States. These provinces also compare favorably in the sense that they are both elevated regions of extensional tectonics and extensive volcanism.

  11. Peracarida populations of hard substrate assemblages in ports of the NW Aegean Sea (eastern Mediterranean)

    NASA Astrophysics Data System (ADS)

    Chintiroglou, C.-C.; Antoniadou, C.; Baxevanis, A.; Damianidis, P.; Karalis, P.; Vafidis, D.

    2004-02-01

    This study deals with the structure of Peracarida populations in four ports in the NW Aegean Sea, Greece, and with the degree this structure is influenced by the particular biotic and abiotic conditions that prevail in the ports. Quantitative samples were taken during summer and winter in two successive years from artificial hard substrates and were analysed using common biocoenotic methods. The examination of approximately 81,250 specimens revealed the presence of 24 Peracarida species, the most dominant of which were Corophium acutum, Leptochelia savignyi and Elasmopus rapax. All species are very common and have been reported from many sites and assemblages in the N Aegean Sea. The ratios of certain Peracarida genera are discussed as possible indicators of environmental health that may be used in long-term biomonitoring programmes on the impact of pollution in harbours.

  12. Diagnostics of Cyclogenesis Over the Aegean Sea Using Potential Vorticity Inversion

    NASA Astrophysics Data System (ADS)

    Flocas, H. A.

    In this study an attempt is made to investigate comprehensively the dynamics of a case of cyclogenesis over the Aegean Sea within the context of the potential vorticity. At early stages the cyclogenesis is manifested by a large scale development at the upper levels over Adriatic Sea and Yugoslavia associated with an upper tropospheric potential vorticity anomaly. At later stages a smaller scale development was generated over Aegean Sea associated with a low-level potential vorticity anomaly and a surface warm anomaly. By means of a two-dimensional potential vorticity inversion it is demonstrated that the scale, the position and the strength of the involved anomalies contribute to the surface development, however, the low-level potential vorticity anomaly seems to constitute the most significant feature, more likely to be associated with condensation.

  13. Assessment of organotin (butyltin species) contamination in marine biota from the Eastern Aegean Sea, Turkey.

    PubMed

    Kucuksezgin, F; Aydin-Onen, S; Gonul, L T; Pazi, I; Kocak, F

    2011-09-01

    The marine environment continues to be adversely affected by tributyltin (TBT) release from maritime traffic. Therefore the concentrations of TBT, dibutyltin (DBT) and monobutyltin (MBT) were measured in barnacles, mussels and fish along the Eastern Aegean coastline. The average concentrations of TBT ng Sn g⁻¹ were found to be 235 in fish, 116 in mussels and 635 in barnacles. The highest concentrations of TBT, DBT and MBT were observed in the barnacles which had been sampled in marinas and harbors. All mussels sampled showed values of TBT+DBT, which were below the "tolerable average residue level (TARL)" as currently accepted. This indicates a lack of risk to the consumer. However, 7 out of the 15 fish sampled displayed TBT+DBT levels above the TARL, which indicates that a fish consumer group may be at risk. Barnacles have high potential as biomonitors for the presence of organotin in the Aegean Sea.

  14. Revisiting the insect mitochondrial molecular clock: the mid-Aegean trench calibration.

    PubMed

    Papadopoulou, Anna; Anastasiou, Ioannis; Vogler, Alfried P

    2010-07-01

    Phylogenetic trees in insects are frequently dated by applying a "standard" mitochondrial DNA (mtDNA) clock estimated at 2.3% My(-1), but despite its wide use reliable calibration points have been lacking. Here, we used a well-established biogeographic barrier, the mid-Aegean trench separating the western and eastern Aegean archipelago, to estimate substitution rates in tenebrionid beetles. Cytochrome oxidase I (cox1) for six codistributed genera across 28 islands (444 individuals) on both sides of the mid-Aegean trench revealed 60 independently coalescing entities delimited with a mixed Yule-coalescent model. One representative per entity was used for phylogenetic analysis of mitochondrial (cox1, 16S rRNA) and nuclear (Mp20, 28S rRNA) genes. Six nodes marked geographically congruent east-west splits whose separation was largely contemporaneous and likely to reflect the formation of the mid-Aegean trench at 9-12 Mya. Based on these "known" dates, a divergence rate of 3.54% My(-1) for the cox1 gene (2.69% when combined with the 16S rRNA gene) was obtained under the preferred partitioning scheme and substitution model selected using Bayes factors. An extensive survey suggests that discrepancies in mtDNA substitution rates in the entomological literature can be attributed to the use of different substitution models, the use of different mitochondrial gene regions, mixing of intraspecific with interspecific data, and not accounting for variance in coalescent times or postseparation gene flow. Different treatments of these factors in the literature confound estimates of mtDNA substitution rates in opposing directions and obscure lineage-specific differences in rates when comparing data from various sources.

  15. Analysis and Modeling Using Multi-Year Satellite Observations in the Aegean and Eastern Mediterranean Seas

    DTIC Science & Technology

    2006-12-01

    a network of buoys in in the Mediterranean Sea, as observed by the TOPEX/Posei R9 Aegean Sea, maintained by the Hellenic Centre for radar altimeter...Ocean Associates, 2004], including an imaging found in the circulation of the Western Mediterranean radar on the Space Shuttle. Two sources of data...numerical simu- high-resolution visible images and synthetic aperture lation of circulation by Pinardi et al. [1997] showed radar (SAR) images. that

  16. Extensional and Transtensional Tectonics of the Manihiki Plateau, Western Equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Coffin, M. F.; Werner, R.; Hauff, F.; Hoernle, K.; Scientific Party, F.

    2007-12-01

    Standing several kilometers above surrounding seafloor, the submarine Manihiki Plateau, an oceanic large igneous province (LIP), encompasses ~800,000 km2 of seafloor in the western equatorial Pacific Ocean. Of Early Cretaceous (~120 Ma) age, the plateau comprises three major structural highs. The High Plateau to the east contains several islands, including the eponymous Manihiki atoll. To the west, the Western Plateaus lie approximately one kilometer deeper; they are bifurcated by elongated, overall northeast-trending, bathymetric lows known as the Danger Islands troughs (DITs). North of the Western Plateaus is the small, nearly separate North Plateau that is separated from the High Plateau (and contiguous NE portion of the Western Plateaus) by the High-North Basin. In May-June 2007, we acquired extensive multibeam bathymetry and reflectivity over all three structural highs and their flanks during the 40-day F.S. Sonne cruise 193. On the basis of these new as well as pre-existing data, we propose a tectonic model for post-emplacement, probable Late Cretaceous deformation of the Manihiki Plateau involving both extensional and transtensional deformation. In our model, the High-North Basin probably formed by seafloor spreading; the northwestern margin of the contiguous NE portion of the Western Plateaus-High Plateau and the southeastern margin of the North Plateau are conjugate rifted margins, whose separation approximately equals the right-lateral offset between the southern flanks of Western Plateaus on either side of the DITs. The curvilinear southwest boundary of the High-North Basin consists of several pull-apart basins that abut the steep northeast flank of the Western plateaus; LIP and normal oceanic crust are juxtaposed along this boundary. The right-lateral relict plate boundary continues uninterrupted to the south of the deep ocean basin as the DITs, which in the study area comprise a series of major en echelon, right- lateral faults that step to the right

  17. Evolution of freshwater crab diversity in the Aegean region (Crustacea: Brachyura: Potamidae).

    PubMed

    Jesse, Ruth; Grudinski, Melanie; Klaus, Sebastian; Streit, Bruno; Pfenninger, Markus

    2011-04-01

    The aim of this study was to estimate the influence of the palaeogeographic and climatic history of the Aegean region on the diversity of freshwater crabs of the genus Potamon and to test whether this area served as source or reservoir in species diversity. Necessary species delimitation was accomplished by phylogenetic analyses of the mitochondrial markers COX1 and ND1, partial 16S rRNA gene and the tRNALeu gene. We found 14 genetic lineages of which nine could be assigned to previously recognised species. Temporal estimates of the splitting pattern in the phylogeny of Potamon indicated that a combination of geological and climatic events influenced their diversification. Within Potamon, the lineages separated into a western group and an eastern group. This first split in the genus occurred approximately 8.3-5.5 Mya, thus possibly correlated with the Messinian salinity crisis. A likelihood approach to geographic range evolution suggested for most species, occurring in the Aegean area, an origin in the Middle East. Moreover, there were no insular endemics in the central Aegean archipelago, therefore low sea-levels during the Pleistocene glacial periods possibly enabled dispersal to these islands, but subsequent rise in sea-level did not cause speciation. Nevertheless, the diversification of most lineages occurred during the Pleistocene epoch thus coinciding with Quaternary fluctuations of the climate.

  18. Large-scale bioprospecting of cyanobacteria, micro- and macroalgae from the Aegean Sea.

    PubMed

    Montalvão, Sofia; Demirel, Zeliha; Devi, Prabha; Lombardi, Valter; Hongisto, Vesa; Perälä, Merja; Hattara, Johannes; Imamoglu, Esra; Tilvi, Supriya Shet; Turan, Gamze; Dalay, Meltem Conk; Tammela, Päivi

    2016-05-25

    Marine organisms constitute approximately one-half of the total global biodiversity, being rich reservoirs of structurally diverse biofunctional components. The potential of cyanobacteria, micro- and macroalgae as sources of antimicrobial, antitumoral, anti-inflammatory, and anticoagulant compounds has been reported extensively. Nonetheless, biological activities of marine fauna and flora of the Aegean Sea have remained poorly studied when in comparison to other areas of the Mediterranean Sea. In this study, we screened the antimicrobial, antifouling, anti-inflammatory and anticancer potential of in total 98 specimens collected from the Aegean Sea. Ethanol extract of diatom Amphora cf capitellata showed the most promising antimicrobial results against Candida albicans while the extract of diatom Nitzschia communis showed effective results against Gram-positive bacterium, S. aureus. Extracts from the red alga Laurencia papillosa and from three Cystoseira species exhibited selective antiproliferative activity against cancer cell lines and an extract from the brown alga Dilophus fasciola showed the highest anti-inflammatory activity as measured in primary microglial and astrocyte cell cultures as well as by the reduction of proinflammatory cytokines. In summary, our study demonstrates that the Aegean Sea is a rich source of species that possess interesting potential for developing industrial applications.

  19. Microfluidic converging/diverging channels optimised for homogeneous extensional deformation

    PubMed Central

    Zografos, K.; Oliveira, M. S. N.

    2016-01-01

    In this work, we optimise microfluidic converging/diverging geometries in order to produce constant strain-rates along the centreline of the flow, for performing studies under homogeneous extension. The design is examined for both two-dimensional and three-dimensional flows where the effects of aspect ratio and dimensionless contraction length are investigated. Initially, pressure driven flows of Newtonian fluids under creeping flow conditions are considered, which is a reasonable approximation in microfluidics, and the limits of the applicability of the design in terms of Reynolds numbers are investigated. The optimised geometry is then used for studying the flow of viscoelastic fluids and the practical limitations in terms of Weissenberg number are reported. Furthermore, the optimisation strategy is also applied for electro-osmotic driven flows, where the development of a plug-like velocity profile allows for a wider region of homogeneous extensional deformation in the flow field. PMID:27478523

  20. Extensional instability in electro-osmotic microflows of polymer solutions

    NASA Astrophysics Data System (ADS)

    Bryce, R. M.; Freeman, M. R.

    2010-03-01

    Fluid transport in microfluidic systems typically is laminar due to the low Reynolds number characteristic of the flow. The inclusion of suspended polymers imparts elasticity to fluids, allowing instabilities to be excited when substantial polymer stretching occurs. For high molecular weight polymer chains we find that flow velocities achievable by standard electro-osmotic pumping are sufficient to excite extensional instabilities in dilute polymer solutions. We observe a dependence in measured fluctuations on polymer concentration which plateaus at a threshold corresponding to the onset of significant molecular crowding in macromolecular solutions; plateauing occurs well below the overlap concentration. Our results show that electro-osmotic flows of complex fluids are disturbed from the steady regime, suggesting potential for enhanced mixing and requiring care in modeling the flow of complex liquids such as biopolymer suspensions.

  1. Microfluidic converging/diverging channels optimised for homogeneous extensional deformation.

    PubMed

    Zografos, K; Pimenta, F; Alves, M A; Oliveira, M S N

    2016-07-01

    In this work, we optimise microfluidic converging/diverging geometries in order to produce constant strain-rates along the centreline of the flow, for performing studies under homogeneous extension. The design is examined for both two-dimensional and three-dimensional flows where the effects of aspect ratio and dimensionless contraction length are investigated. Initially, pressure driven flows of Newtonian fluids under creeping flow conditions are considered, which is a reasonable approximation in microfluidics, and the limits of the applicability of the design in terms of Reynolds numbers are investigated. The optimised geometry is then used for studying the flow of viscoelastic fluids and the practical limitations in terms of Weissenberg number are reported. Furthermore, the optimisation strategy is also applied for electro-osmotic driven flows, where the development of a plug-like velocity profile allows for a wider region of homogeneous extensional deformation in the flow field.

  2. Extensional Relaxation Times and Pinch-off Dynamics of Dilute Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Dinic, Jelena; Zhang, Yiran; Jimenez, Leidy; Sharma, Vivek

    2015-11-01

    We show that visualization and analysis of capillary-driven thinning and pinch-off dynamics of the columnar neck in an asymmetric liquid bridge created by dripping-onto-substrate can be used for characterizing the extensional rheology of complex fluids. Using a particular example of dilute, aqueous PEO solutions, we show the measurement of both the extensional relaxation time and extensional viscosity of weakly elastic, polymeric complex fluids with low shear viscosity η< 20 mPa .s and relatively short relaxation time, λ <1 ms. Characterization of elastic effects and extensional relaxation times in these dilute solutions is beyond the range measurable in the standard geometries used in commercially available shear and extensional rheometers (including CaBER, capillary breakup extensional rheometer). As the radius of the neck that connects a sessile drop to a nozzle is detected optically, and the extensional response for viscoelastic fluids is characterized by analyzing their elastocapillary self-thinning, we refer to this technique as optically-detected elastocapillary self-thinning dripping-onto-substrate (ODES-DOS) extensional rheometry.

  3. The Extensional Rheology of Non-Newtonian Materials

    NASA Technical Reports Server (NTRS)

    Spiegelberg, Stephen H.; McKinley, Gareth H.

    1996-01-01

    The evolution of the transient extensional stresses in dilute and semi-dilute viscoelastic polymer solutions are measured with a filament stretching rheometer of a design similar to that first introduced by Sridhar, et al. The solutions are polystyrene-based (PS) Boger fluids that are stretched at constant strain rates ranging from 0.6 less than or equal to epsilon(0) less than or equal to 4s(exp -1) and to Hencky strains of epsilon greater than 4. The test fluids all strain harden and Trouton ratios exceeding 1000 are obtained at high strains. The experimental data strain hardens at lower strain levels than predicted by bead-spring FENE models. In addition to measuring the transient tensile stress growth, we also monitor the decay of the tensile viscoelastic stress difference in the fluid column following cessation of uniaxial elongation as a function of the total imposed Hencky strain and the strain rate. The extensional stresses initially decay very rapidly upon cessation of uniaxial elongation followed by a slower viscoelastic relaxation, and deviate significantly from FENE relaxation predictions. The relaxation at long times t is greater than or equal to 5 s, is compromised by gravitational draining leading to non-uniform filament profiles. For the most elastic fluids, partial decohension of the fluid filament from the endplates of the rheometer is observed in tests conducted at high strain rates. This elastic instability is initiated near the rigid endplate fixtures of the device and it results in the progressive breakup of the fluid column into individual threads or 'fibrils' with a regular azimuthal spacing. These fibrils elongate and bifurcate as the fluid sample is elongated further. Flow visualization experiments using a modified stretching device show that the instability develops as a consequence of an axisymmetry-breaking meniscus instability in the nonhomogeneous region of highly deformed fluid near the rigid endplate.

  4. Backarc extension, detachments and granitoids in the Aegean, their relations to slab tear and asthenospheric flow

    NASA Astrophysics Data System (ADS)

    Jolivet, Laurent; Menant, Armel; Rabillard, Aurélien; Arbaret, Laurent; Augier, Romain; Gumiaux, Charles

    2013-04-01

    The Cycladic granitoids (Ikaria, Mykonos, Naxos, Kos, Lavrion, Serifos, Tinos) intruded the Aegean crust during a rather short period (17-10 Ma) compared to the much longer Oligo-Miocene crustal thinning phase (35 Ma to the Present). Their geochemical characteristics show that their sources have changed through time and space, with a progressive decreasing component of continental crust contamination with time and from east to west. They all interacted with large-scale detachments, namely the North Cycladic Detachment System (NCDS) in the north and the West Cycladic Detachment System (WCDS) in the south. In Mykonos, Naxos, Serifos and Ikaria the plutons are also associated with a high-temperature metamorphic dome of Miocene age. Their intrusion period roughly covers the same time window as the fast clockwise rotation of the western Aegean evidenced by paleomagnetic measurements and they are contemporaneous with a surge of alkaline volcanism in the eastern Aegean that can be related to a slab tear imaged below western Anatolia. The continental crust component in the Middle Miocene Cycladic plutons is not found in the early Miocene plutons of the northern Aegean, like in Kavala and Vrondou. They thus probably record a quite sudden thermal event in the Cyclades that led to the partial melting of the extending deep crust. We propose a model involving slab tear starting at ~17 Ma, fast retreat of the slab west of the tear and southwestward influx of hot asthenospheric material below the Aegean crust, leading to melting of the lower crust. Partial melting of the whole lower crust above the hot asthenospheric flow could explain the flat Moho observed below the Cyclades. The close proximity of plutons with the detachments suggests that their ascent toward the upper crust is favoured by the extreme extension at work there. The first granitoids in the region of the tear (Ikaria) are the richest in crustal component and this component decreases while the crust thins more and

  5. The spreading of the Chernobyl signature from the North Aegean waters to the Eastern Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Papucci, C.; Delfanti, R.; Lorenzelli, R.; Zervakis, V.; Georgopoulos, D.

    2003-04-01

    The Chernobyl accident (26 April 1986) produced a patchy deposition of radionuclides over the Eastern and Northern basins of the Mediterranean Sea, that was superimposed over the previous fallout from atmospheric nuclear weapon tests. The deposition of Chernobyl-derived 137Cs was particularly heavy onto the Black Sea (3000 TBq) and the Aegean -- Ionian Seas along the Greek coasts (800 TBq). Moreover, as the Black Sea still receives a delayed input of Chernobyl 137Cs from the rivers Danube and Dniepr, the output of surface water through the Dardanelles Straits constitutes a "permanent" point source of this conservative radionuclide into the North Aegean Sea. The water exiting the Dardanelles undergoes mixing with North Aegean surface water. Due to its low salinity this water acts as an insulation layer and, consequently, deep-water formation is rather infrequent in the North Aegean, taking place only at periods of reduced Black Sea outflow and/or exceptionally cold and dry winters. In the last 20 years there have been two major deep-water formation events in the North Aegean: in winter 1987 (just after the Chernobyl accident), and in winter 1993. Actually, these two episodes have deeply modified the vertical profiles of 137Cs with respect to 1984, before the Chernobyl accident. In 1999--2001, in the (isolated from advection) Lemnos and N-Skyros Basins, the 137Cs concentration increased from the surface to the bottom; in the deep waters it was about 5 Bq m-3, five times higher than in 1984. These deep waters formed in 1993, are characterised by high salinity and density and their major contributor was water of Levantine/Cretan origin. The Chernobyl input also caused a considerable increase in 137Cs concentrations in the Cretan Deep Waters flowing through the Antikythera Strait: the typical concentration in this water mass was, in 1999, 2.5 -- 2.8 Bq m-3, almost three times higher than that in the deep Cretan basin in 1984. This strong signal is spreading in the

  6. Aspects of three-dimensional strain at the margin of the extensional orogen, Virgin River depression area, Nevada, Utah, and Arizona

    USGS Publications Warehouse

    Anderson, R.E.; Barnhard, T.P.

    1993-01-01

    The Virgin River depression and surrounding mountains are Neogene features that are partly contiguous with the little-strained rocks of the structural transition to the Colorado Plateau province. This contiguity makes the area ideally suited for evaluating the sense, magnitude, and kinematics of Neogene deformation. Analysis along the strain boundary shows that, compared to the adjacent little-strained area, large-magnitude vertical deformation greatly exceeds extensional deformation and that significant amounts of lateral displacement approximately parallel the province boundary. Isostatic rebound following tectonic denudation is an unlikely direct cause of the strong vertical structural relief adjacent to the strain boundary. Instead, the observed structures are first-order features defining a three-dimensional strain field produced by approximately east-west extension, vertical structural attenuation, and extension-normal shortening. All major structural elements of the strain-boundary strain field are also found in the adjacent Basin and Range. -from Authors

  7. Analysis of Neogene deformation between Beaver, Utah and Barstow, California: Suggestions for altering the extensional paradigm

    USGS Publications Warehouse

    Anderson, R. Ernest; Beard, Sue; Mankinen, Edward A.; Hillhouse, John W.

    2013-01-01

    For more than two decades, the paradigm of large-magnitude (~250 km), northwest-directed (~N70°W) Neogene extensional lengthening between the Colorado Plateau and Sierra Nevada at the approximate latitude of Las Vegas has remained largely unchallenged, as has the notion that the strain integrates with coeval strains in adjacent regions and with plate-boundary strain. The paradigm depends on poorly constrained interconnectedness of extreme-case lengthening estimated at scattered localities within the region. Here we evaluate the soundness of the inferred strain interconnectedness over an area reaching 600 km southwest from Beaver, Utah, to Barstow, California, and conclude that lengthening is overestimated in most areas and, even if the estimates are valid, lengthening is not interconnected in a way that allows for published versions of province-wide summations.We summarize Neogene strike slip in 13 areas distributed from central Utah to Lake Mead. In general, left-sense shear and associated structures define a broad zone of translation approximately parallel to the eastern boundary of the Basin and Range against the Colorado Plateau, a zone we refer to as the Hingeline shear zone. Areas of steep-axis rotation (ranging to 2500 km2) record N-S shortening rather than unevenly distributed lengthening. In most cases, the rotational shortening and extension-parallel folds and thrusts are coupled to, or absorb, strike slip, thus providing valuable insight into how the discontinuous strike-slip faults are simply parts of a broad zone of continuous strain. The discontinuous nature of strike slip and the complex mixture of extensional, contractional, and steep-axis rotational structures in the Hingeline shear zone are similar to those in the Walker Lane belt in the west part of the Basin and Range, and, together, the two record southward displacement of the central and northern Basin and Range relative to the adjacent Colorado Plateau. Understanding this province

  8. Analysis of Neogene deformation between Beaver, Utah, and Barstow, California: suggestions for altering the extensional paradigm

    USGS Publications Warehouse

    Anderson, R. Ernest; Beard, L. Sue; Mankinen, Edward A.; Hillhouse, John W.

    2013-01-01

    For more than two decades, the paradigm of large-magnitude (~250 km), northwest-directed (~N70°W) Neogene extensional lengthening between the Colorado Plateau and Sierra Nevada at the approximate latitude of Las Vegas has remained largely unchallenged, as has the notion that the strain integrates with coeval strains in adjacent regions and with plate-boundary strain. The paradigm depends on poorly constrained interconnectedness of extreme-case lengthening estimated at scattered localities within the region. Here we evaluate the soundness of the inferred strain interconnectedness over an area reaching 600 km southwest from Beaver, Utah, to Barstow, California, and conclude that lengthening is overestimated in most areas and, even if the estimates are valid, lengthening is not interconnected in a way that allows for published versions of province-wide summations. We summarize Neogene strike slip in 13 areas distributed from central Utah to Lake Mead. In general, left-sense shear and associated structures define a broad zone of translation approximately parallel to the eastern boundary of the Basin and Range against the Colorado Plateau, a zone we refer to as the Hingeline shear zone. Areas of steep-axis rotation (ranging to 2500 km2) record N-S shortening rather than unevenly distributed lengthening. In most cases, the rotational shortening and extension-parallel folds and thrusts are coupled to, or absorb, strike slip, thus providing valuable insight into how the discontinuous strike-slip faults are simply parts of a broad zone of continuous strain. The discontinuous nature of strike slip and the complex mixture of extensional, contractional, and steep-axis rotational structures in the Hingeline shear zone are similar to those in the Walker Lane belt in the west part of the Basin and Range, and, together, the two record southward displacement of the central and northern Basin and Range relative to the adjacent Colorado Plateau. Understanding this province

  9. Isotopic evidence of source variations in commingled magma systems: Colorado River extensional corridor, Arizona and Nevada

    SciTech Connect

    Metcalf, R.V.; Smith, E.I.; Martin, M.W. . Dept. of Geoscience); Gonzales, D.A.; Walker, J.D. . Isotope Geochronology Lab.)

    1993-04-01

    Mixing of mantle derived mafic and crustal derived felsic magmas is a major Province-wide process forming Tertiary intermediate magmas within the Basin and Range. Major variations in magma sources, however, may exist in temporally and spatially related systems. Such variations are exemplified by two closely spaced plutons within the northern Colorado River extensional corridor. The 15.96 Ma Mt. Perkins pluton (MPP) was emplaced in three major phases: phase 1 (oldest) gabbro; phase 2 quartz diorite to hornblende granodiorite; and phase 3 biotite granodiorite ([+-]hbld). Phases 2 and 3 contain mafic microgranitoid enclaves (MME) that exhibit evidence of magma mingling. Combined data from phase 2 and 3 rocks, including MMW, shows positive [sup 87]Sr/[sup 86]Sr and negative [var epsilon]Nd correlations vs. SiO[sub 2] (50--72 wt %). Phase 2 rocks, which plot between phase 2 MME and MME-free phase 3 granodiorite, represent hybrid magmas formed by mixing of mantle and crustal derived magmas. Phase 1 gabbro falls off isotope-SiO[sub 2] trends and represents a separate mantle derived magma. The 13.2 Ma Wilson Ridge pluton (WRP), <20 km north of MPP, is cogenetic with the river Mountains volcano (RMV). In WRP an early diorite was intruded by a suite of monzodiorite to quartz monzonite. The monzodiorite portion contains MME and mafic schlieren representing mingled and mixed mafic magmas. The WRP and MPP represent two closely spaced isotopically distinct and separate magma systems. There are five magma sources. The two felsic mixing end members represent two different crustal magma sources. Two mantle sources are presented by MPP phase 1 gabbro and phase 2 MME, reflecting lithospheric and asthenospheric components, respectively. The latter represents the oldest reported Tertiary asthenospheric component within the region. A single lithospheric mantle source, different from the MPP gabbro, is indicated for the mafic mixing end member in the WRP-RMV suite.

  10. Hydrodynamic extensional stress during the bubble bursting process for bioreactor system design

    NASA Astrophysics Data System (ADS)

    Tran, Thanh Tinh; Lee, Eun Gyo; Lee, In Su; Woo, Nam Sub; Han, Sang Mok; Kim, Young Ju; Hwang, Wook Ryol

    2016-11-01

    Cell damage, one of critical issues in the bioreactor design for animal cell culture, is caused mainly from the bubble bursting at the free surface subjected to strong extensional flows. In this work, extensive computational studies are performed to investigate bubble bursting process in great details. Extensive numerical simulations are performed for a wide range of bubble diameters (from 0.5 to 6 mm) and the surface tension values (from 0.03 to 0.072 N/m), with which effects of the bubble size and surfactant (PF68) concentration on the hydrodynamic stress are investigated. For all the cases, the maximum extensional stress appears at the instance when receding films impact each other at the bottom of the bubble. A model equation based on numerical simulations is presented to predict the maximum extensional stress as a function of the bubble diameter and the surface tension. The bubble diameter has turned out to contribute significantly the maximum hydrodynamic extensional stress. In addition, the bubble collapsed time and the affected volume around a bubble subjected to the critical extensional stress are investigated. The extensional stress estimation is reported as a function of the bubble size and the surface tension. The influence of the bubble size on the maximum stress dominates and extensional stress reaches up to the order of 104 Pa for bubble size of 0.5 mm.

  11. Quantitative identification and analysis of sub-seismic extensional structure system: technique schemes and processes

    NASA Astrophysics Data System (ADS)

    Chenghua, Ou; Chen, Wei; Ma, Zhonggao

    2015-06-01

    Quantitative characterization of complex sub-seismic extensional structure system that essentially controls petroleum exploitation is difficult to implement in seismic profile interpretation. This research, based on a case study in block M of Myanmar, established a set of quantitative treatment schemes and technique processes for the identification of sub-seismic low-displacement (SSLD) extensional faults or fractures upon structural deformation restoration and geometric inversion. Firstly, the master-subsidiary inheritance relations and configuration of the seismic-scale extensional fault systems are determined by analyzing the structural pattern. Besides, three-dimensional (3D) pattern and characteristics of the seismic-scale extensional structure have been illustrated by a 3D structure model built upon seismic sections. Moreover, according to the dilatancy obtained from structural restoration on the basis of inclined shear method, as well as the fracture-flow index, potential SSLD extensional faults or fractures have been quantitatively identified. Application of the technique processes to the sub-seismic low-displacement extensional structures in block M in Myanmar is instructive to quantitatively interpret those SSLD extensional structure systems in practice.

  12. A detailed seismic zonation model for shallow earthquakes in the broader Aegean area

    NASA Astrophysics Data System (ADS)

    Vamvakaris, D. A.; Papazachos, C. B.; Papaioannou, Ch. A.; Scordilis, E. M.; Karakaisis, G. F.

    2016-01-01

    In the present work we propose a new seismic zonation model of area type sources for the broader Aegean area, which can be readily used for seismic hazard assessment. The definition of this model is based not only on seismicity information but incorporates all available seismotectonic and neotectonic information for the study area, in an attempt to define zones which show not only a rather homogeneous seismicity release but also exhibit similar active faulting characteristics. For this reason, all available seismological information such as fault plane solutions and the corresponding kinematic axes have been incorporated in the analysis, as well as information about active tectonics, such as seismic and active faults. Moreover, various morphotectonic features (e.g. relief, coastline) were also considered. Finally, a revised seismic catalogue is employed and earthquake epicentres since historical times (550 BC-2008) are employed, in order to define areas of common seismotectonic characteristics, that could constitute a discrete seismic zone. A new revised model of 113 earthquake seismic zones of shallow earthquakes for the broader Aegean area is finally proposed. Using the proposed zonation model, a detailed study is performed for the catalogue completeness for the recent instrumental period.Using the defined completeness information, seismicity parameters (such as G-R values) for the 113 new seismic zones have been calculated, and their spatial distribution was also examined. The spatial variation of the obtained b values shows an excellent correlation with the geotectonic setting in the area, in good agreement with previous studies. Moreover, a quantitative estimation of seismicity is performed in terms of the mean return period, Tm, of large (M ≥ 6.0) earthquakes, as well as the most frequent maximum magnitude, Mt, for a typical time period (T = 50 yr), revealing significant spatial variations of seismicity levels within the study area. The new proposed

  13. Zircon crytallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    USGS Publications Warehouse

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Miff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ??? 60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction). ?? 2007 Geological Society of America.

  14. Zircon crystallization and recycling in the magma chamber of the rhyolitic Kos Plateau Tuff (Aegean arc)

    USGS Publications Warehouse

    Bachman, O.; Charlier, B.L.A.; Lowenstern, J. B.

    2007-01-01

    In contrast to most large-volume silicic magmas in continental arcs, which are thought to evolve as open systems with significant assimilation of preexisting crust, the Kos Plateau Tuff magma formed dominantly by crystal fractionation of mafic parents. Deposits from this ~60 km3 pyroclastic eruption (the largest known in the Aegean arc) lack xenocrystic zircons [secondary ion mass spectrometry (SIMS) U-Pb ages on zircon cores never older than 500 ka] and display Sr-Nd whole-rock isotopic ratios within the range of European mantle in an area with exposed Paleozoic and Tertiary continental crust; this evidence implies a nearly closed-system chemical differentiation. Consequently, the age range provided by zircon SIMS U-Th-Pb dating is a reliable indicator of the duration of assembly and longevity of the silicic magma body above its solidus. The age distribution from 160 ka (age of eruption by sanidine 40Ar/39Ar dating; Smith et al., 1996) to ca. 500 ka combined with textural characteristics (high crystal content, corrosion of most anhydrous phenocrysts, but stability of hydrous phases) suggest (1) a protracted residence in the crust as a crystal mush and (2) rejuvenation (reduced crystallization and even partial resorption of minerals) prior to eruption probably induced by new influx of heat (and volatiles). This extended evolution chemically isolated from the surrounding crust is a likely consequence of the regional geodynamics because the thinned Aegean microplate acts as a refractory container for magmas in the dying Aegean subduction zone (continent-continent subduction).

  15. Peeling flexible beams in viscous fluids: Rigidity and extensional compliance

    NASA Astrophysics Data System (ADS)

    Dhong, Charles; Fréchette, Joëlle

    2017-01-01

    We describe small angle peeling measurements in completely submerged environments to study the coupling between viscous forces and the mechanical properties of the plates being peeled. During the experiments, the plates resist motion because of lubrication forces while van der Waals forces between the plates and the static surface are negligible. In particular, we study the role played by flexural rigidity in the force-displacement curves and in the energy release rate. We show that the coupling between the viscous forces and the flexural rigidity of the plates dictates the shape and magnitude of the force-displacement curves. We develop simple scaling relationships that combine the lubrication forces with an Euler-Bernoulli beam to extract how the peak force and energy release rates depend on the ratio between rigidity and viscosity, and show good agreement between the predictions and experimental results. We also show that increasing the extensional compliance leads to a decrease in both the force-displacement curve and in the energy release rate. We then demonstrate that this reduction can be interpreted in terms of a stress decay length.

  16. Extensional diapirism in the eastern Prebetic foldbelt, southeastern Spain

    SciTech Connect

    Ruig, M.J. de

    1996-12-31

    The influence of tectonic stress on the initiation and development of evaporite diapirs is of great importance in the interpretation of diapiric structures and associated sediments. The eastern Prebetic foldbelt in southeastern Spain contains many diapirs that provide excellent examples of tectonically controlled diapirism. These diapirs are mainly composed of Triassic evaporite and shale that have pierced their overburden along extensional faults and in releasing oversteps along strike-slip faults. They occur as highly elongated diapiric walls or as large, fault-bounded bodies that can cover several tens of square kilometers at the center of grabens. Most of these diapirs reached the surface in Neogene times, constituting local depocenters for Miocene sediments. Outcrop and well data suggest that their source layer consists mainly of interbedded shale and anhydrite, which are denser than their carbonate overburden and thus preclude piercement diapirism driven by buoyancy. The external geometry of these diapirs and a variety of kinematic indicators in surrounding overburden suggest that their location and initiation was primarily controlled by (trans)tensional faulting. It is therefore concluded that the Prebetic diapirs formed in response to thin-skinned extension of their overburden, which induced differential loading and viscous flow of the Triassic evaporites. Regional paleostress analysis and chronostratigraphic correlation suggest that diapirism was triggered by rifting in the adjacent Western Mediterranean Basin.

  17. Shear History Extensional Rheology Experiment: A Proposed ISS Experiment

    NASA Technical Reports Server (NTRS)

    Hall, Nancy R.; Logsdon, Kirk A.; Magee, Kevin S.

    2007-01-01

    The Shear History Extensional Rheology Experiment (SHERE) is a proposed International Space Station (ISS) glovebox experiment designed to study the effect of preshear on the transient evolution of the microstructure and viscoelastic tensile stresses for monodisperse dilute polymer solutions. Collectively referred to as Boger fluids, these polymer solutions have become a popular choice for rheological studies of non-Newtonian fluids and are the non-Newtonian fluid used in this experiment. The SHERE hardware consists of the Rheometer, Camera Arm, Interface Box, Cabling, Keyboard, Tool Box, Fluid Modules, and Stowage Tray. Each component will be described in detail in this paper. In the area of space exploration, the development of in-situ fabrication and repair technology represents a critical element in evolution of autonomous exploration capability. SHERE has the capability to provide data for engineering design tools needed for polymer parts manufacturing systems to ensure their rheological properties have not been impacted in the variable gravity environment and this will be briefly addressed.

  18. Measuring Cell Viscoelastic Properties Using a Microfluidic Extensional Flow Device.

    PubMed

    Guillou, Lionel; Dahl, Joanna B; Lin, Jung-Ming G; Barakat, AbduI I; Husson, Julien; Muller, Susan J; Kumar, Sanjay

    2016-11-01

    The quantification of cellular mechanical properties is of tremendous interest in biology and medicine. Recent microfluidic technologies that infer cellular mechanical properties based on analysis of cellular deformations during microchannel traversal have dramatically improved throughput over traditional single-cell rheological tools, yet the extraction of material parameters from these measurements remains quite complex due to challenges such as confinement by channel walls and the domination of complex inertial forces. Here, we describe a simple microfluidic platform that uses hydrodynamic forces at low Reynolds number and low confinement to elongate single cells near the stagnation point of a planar extensional flow. In tandem, we present, to our knowledge, a novel analytical framework that enables determination of cellular viscoelastic properties (stiffness and fluidity) from these measurements. We validated our system and analysis by measuring the stiffness of cross-linked dextran microparticles, which yielded reasonable agreement with previously reported values and our micropipette aspiration measurements. We then measured viscoelastic properties of 3T3 fibroblasts and glioblastoma tumor initiating cells. Our system captures the expected changes in elastic modulus induced in 3T3 fibroblasts and tumor initiating cells in response to agents that soften (cytochalasin D) or stiffen (paraformaldehyde) the cytoskeleton. The simplicity of the device coupled with our analytical model allows straightforward measurement of the viscoelastic properties of cells and soft, spherical objects.

  19. Aegean tectonics, a record of slab-overriding plate interactions (Invited)

    NASA Astrophysics Data System (ADS)

    Jolivet, L.; Faccenna, C.; Huet, B.; Lecomte, E.; Labrousse, L.; Denèle, Y.; Le Pourhiet, L.; Lacombe, O.; Burov, E. B.; Meyer, B.; Suc, J.; Popescu, S.; Monié, P.; Philippon, M.; Gueydan, F.; Brun, J.; Paul, A.; Salaün, G.; Armijo, R.

    2010-12-01

    Two opposing visions of the Aegean backarc tectonics implicitly contain contrasting images of the rheological behaviour of the lihosphere, supported by different sets of observations. The propagation of the NAF and extension in the Corinth Rift suggest a strongly localising rheology whereas the formation of MCC in the Cyclades and the Rhodope suggests instead a more viscous behaviour. This paradox was the seminal question addressed by the ANR-EGEO programme (2007-2010) that leads to the following conclusions: (1) The exhumation of the Cycladic MCC’s is accommodated by the N-dipping North Cycladic Detachment System (NCDS) that partly reworks the Vardar suture and at the base by a series of thrusts, including the basal contact of the Cycladic Blueschists (CBS) over the Cycladic Basement (CB). The activity of LANF is due to the reactivation of pre-existing discontinuities such as thrusts or earlier detachments and much less to the interaction with granitic plutons. (2) Exhumation in the Cyclades has proceeded in two stages: (a) Eocene syn-orogenic exhumation within the subduction lower/upperplate interface while the post-orogenic Rhodope MCC formed further north, (b) Oligo-Miocene post-orogenic extension in an MCC mode coeval with syn-orogenic exhumation in Crete and the Peloponnese. (3) Both stages were associated with slab retreat, as early as the Eocene with an acceleration at 30-35 Ma. (4) The localisation of the presently active steeply-dipping normal faults on the southern margin of the Corinth Rift may have been preceded by a partial reworking of thrusts and syn-orogenic detachments by shallow-dipping decollements. (5) The localisation of the NAF in the Marmara Sea region and the Northern Aegean Sea is now accurately dated between 5.3 and 5 Ma Ma using the erosion and deposition surfaces that mark the Messinian salinity Crisis and nannofossils ages. (6) The formation of MCCs in the Cyclades resulted in the draining of the low viscosity lower crust from the

  20. Three-dimensional instantaneous dynamics modeling of present-day Aegean subduction

    NASA Astrophysics Data System (ADS)

    Glerum, Anne; Thieulot, Cedric; Pranger, Casper; van Hinsbergen, Douwe; Fraters, Menno; Spakman, Wim

    2015-04-01

    The Aegean region (Eastern Mediterranean) is exemplary of the interaction between crustal tectonics, plate motion, subduction and mantle flow: African subduction underneath the region has been continuous for at least the last 100 My, leading to about 2100-2500 km of subducted lithosphere residing in the mantle (van Hinsbergen et al., 2005). During this subduction, decoupled upper continental and oceanic crust accreted into a wedge of stacked nappes. In turn, these nappes have been significantly extended, predominantly during the last 25 My, due to the retreat of the African slab relative to Eurasia (van Hinsbergen and Schmid, 2012). As a first step to better understanding the coupling of the tectonic evolution of the crust and the underlying mantle dynamics, we are developing 3-D numerical models of the instantaneous dynamics of the present-day Aegean subduction system using the finite element code ASPECT (Kronbichler et al., 2012). The instantaneous models are set up with initial slab geometries derived from tomography and realistic plate boundary configurations and incorporate the major crustal weak zones of the overriding plate. Our modeling results in predictions of flow fields and stress, strain rate and rotation rate fields for the present-day tectonic setting of the Aegean region. By comparing our various model predictions to the widely available observations, such as focal mechanisms, GPS velocities and seismic anisotropy, we aim at an improved understanding of how mantle flow, subduction morphology and possibly slab segmentation, as well as the rheological behavior of the overriding plate, control present-day tectonic deformation. We expect to show preliminary results of this comparison. Kronbichler, M., Heister, T. and Bangerth, W. (2012), High Accuracy Mantle Convection Simulation through Modern Numerical Methods, Geophysical Journal International, 191, 12-29. Van Hinsbergen, D. J. J., Hafkenscheid, E., Spakman, W., Meulenkamp, J. E. and Wortel, R. (2005

  1. The effect of shear and extensional viscosity on atomization in medical inhaler.

    PubMed

    Broniarz-Press, L; Ochowiak, M; Matuszak, M; Włodarczak, S

    2014-07-01

    The paper contains the results of experimental studies of water, aqueous solutions of glycerol and aqueous solutions of glycerol-polyethylene oxide (PEO) atomization process in a medical inhaler obtained by the use of the digital microphotography method. The effect of the shear and extensional viscosity on the drop size, drop size histogram and mean drop diameter has been analyzed. The obtained results have shown that the drop size increases with the increase in shear and extensional viscosity of liquid atomized. Extensional viscosity has a greater impact on the spraying process. It has been shown that the change in liquid viscosity leads to significant changes in drop size distribution. The correlation for Sauter mean diameter as function of the shear and extensional viscosity was proposed.

  2. Shear History Extensional Rheology Experiment II (SHERE II) Microgravity Rheology with Non-Newtonian Polymeric Fluids

    NASA Technical Reports Server (NTRS)

    Jaishankar, Aditya; Haward, Simon; Hall, Nancy Rabel; Magee, Kevin; McKinley, Gareth

    2012-01-01

    The primary objective of SHERE II is to study the effect of torsional preshear on the subsequent extensional behavior of filled viscoelastic suspensions. Microgravity environment eliminates gravitational sagging that makes Earth-based experiments of extensional rheology challenging. Experiments may serve as an idealized model system to study the properties of lunar regolith-polymeric binder based construction materials. Filled polymeric suspensions are ubiquitous in foods, cosmetics, detergents, biomedical materials, etc.

  3. The effects of extensional inheritance on transtensional deformation patterns

    NASA Astrophysics Data System (ADS)

    Naliboff, J.; Buiter, S. J.; Le Pourhiet, L.; May, D.

    2015-12-01

    Continental rifting and breakup frequently occurs through multiple phases of extension in which margin architecture is governed by distinct modes of brittle and viscous deformation, as well as surface processes. Transitions between such phases of extension may in some cases reflect plate-scale changes in extension obliquity and velocity. For example, recent studies indicate that localization of transtensional deformation onto a narrow shear zone in the Gulf of California Rift corresponds temporally with an increase in rift obliquity. Here, we use high-resolution 3-D models (run with pTatin3D) to examine how transtensional deformation patterns evolve with such increases in extension obliquity. Our models build on previous crustal-scale analogue and numerical studies examining oblique reactivation of normal faults. These studies show that the orientation and strength of inherited normal faults strongly control the style of slip and deformation partitioning between new and reactivated faults. While highly insightful, these studies examine deformation over limited spatial extents and do not account for key processes such as isostasy and temperature-dependent rock strength. Here, we model the thermal-mechanical evolution of the lithosphere and asthenosphere to a depth of 200 km. Deformation occurs through an initial phase of orthogonal, Basin and Range style extension, followed by 1-2 phases of extension at different obliquities. The initial lithospheric structure and time-dependent boundary conditions follow geologic observations and plate-reconstructions within the Gulf of California. Our experiments highlight the strong control of inheritance on transtensional crustal deformation. By comparing fault development, crustal thickness evolution and block rotations directly with observations from the Gulf of California and other extensional and transtensional regions, we can better evaluate the relative control of structural inheritance on passive margin architecture.

  4. Vertical diffusion and oxygen consumption during stagnation periods in the deep North Aegean

    NASA Astrophysics Data System (ADS)

    Zervakis, Vassilis; Krasakopoulou, Evangelia; Georgopoulos, Dimitris; Souvermezoglou, Ekaterini

    2003-01-01

    Ventilation of the deep basins of the North Aegean Sea takes place during relatively scarce events of massive dense water formation in that region. In the time intervals between such events, the bottom waters of each sub-basin are excluded from interaction with other water masses through advection or isopycnal mixing and the only process that changes their properties is diapycnal mixing with overlying waters. In this work we utilize a simple one-dimensional model in order to estimate the vertical eddy diffusion coefficient Kρ based on the observed rate of change of density and stratification. Vertical diffusivity is estimated for each of three sub-basins of the North Aegean, one of convex shape of the seabed and the other two of concave topography. It is noteworthy that the convex sub-basin exhibited much higher vertical diffusivity than the two concave sub-basins, a fact consistent with theoretical predictions that internal-wave-induced mixing is higher over the former shape of seabed. Furthermore, the estimates of Kρ are exploited in computing the vertical transport of dissolved oxygen through diffusion and the rate of oxygen consumption by decaying organic matter. The different levels of the estimated diffusion and oxygen consumption rates testify to the dynamical and biogeochemical characteristics of each basin.

  5. The Etesian wind system and wind energy potential over the Aegean Sea

    NASA Astrophysics Data System (ADS)

    Dafka, Stella; Xoplaki, Elena; Garcia-Bustamante, Elena; Toreti, Andrea; Zanis, Prodromos; Luterbacher, Juerg

    2013-04-01

    The Mediterranean region lies in an area of great climatic interest since it is influenced by some of the most relevant mechanisms of the global climate system. In the frame of the three Europe 2020 priorities for a smart, sustainable and inclusive economy delivering high levels of employment, productivity and social cohesion, the Mediterranean energy plan is of paramount importance at the European level, being an area with a significant potential for renewable energy from natural sources that could play an important role in responding to climate change effects over the region. We present preliminary results on a study of the Etesian winds in the past, present and future time. We investigate the variability and predictability of the wind field over the Aegean. Statistical downscaling based on several methodologies will be applied (e.g. canonical correlation analysis and multiple linear regression). Instrumental time series, Era-Interim and the 20CR reanalyses will be used. Large-scale climate drivers as well as the influence of local/regional factors and their interaction with the Etesian wind field will be addressed. Finally, the Etesian wind resources on the present and future climate will be assessed in order to identify the potential areas suitable for the establishment of wind farms and the production of wind power in the Aegean Sea.

  6. Observed TEC Anomalies by GNSS Sites Preceding the Aegean Sea Earthquake of 2014

    NASA Astrophysics Data System (ADS)

    Ulukavak, Mustafa; Yal&ccedul; ınkaya, Mualla

    2016-11-01

    In recent years, Total Electron Content (TEC) data, obtained from Global Navigation Satellites Systems (GNSS) receivers, has been widely used to detect seismo-ionospheric anomalies. In this study, Global Positioning System - Total Electron Content (GPS-TEC) data were used to investigate ionospheric abnormal behaviors prior to the 2014 Aegean Sea earthquake (40.305°N 25.453°E, 24 May 2014, 09:25:03 UT, Mw:6.9). The data obtained from three Continuously Operating Reference Stations in Turkey (CORS-TR) and two International GNSS Service (IGS) sites near the epicenter of the earthquake is used to detect ionospheric anomalies before the earthquake. Solar activity index (F10.7) and geomagnetic activity index (Dst), which are both related to space weather conditions, were used to analyze these pre-earthquake ionospheric anomalies. An examination of these indices indicated high solar activity between May 8 and 15, 2014. The first significant increase (positive anomalies) in Vertical Total Electron Content (VTEC) was detected on May 14, 2014 or 10 days before the earthquake. This positive anomaly can be attributed to the high solar activity. The indices do not imply high solar or geomagnetic activity after May 15, 2014. Abnormal ionospheric TEC changes (negative anomaly) were observed at all stations one day before the earthquake. These changes were lower than the lower bound by approximately 10-20 TEC unit (TECU), and may be considered as the ionospheric precursor of the 2014 Aegean Sea earthquake

  7. Magnetotellurics and Transient Electromagnetics to Investigate the Geoelectric Structure of Southern Aegean, Greece

    NASA Astrophysics Data System (ADS)

    Makris, J. P.; Kalisperi, D.; Smirnov, M.; Rigakis, H.; Romano, G.; Kokologiannakis, A.; Pentes, G.; Pentaris, F.; Skoulakis, A.; Perrone, A.; Kouli, M.; Vallianatos, F.

    2014-12-01

    Since 2012 a great number of onshore magnetotelluric (MT) and Transient Electromagnetic (TEM) measurements have been conducted in Southern Aegean, Greece. The survey included Crete, almost all the islands of Dodecanese and Southern Cyclades, Southern Peloponnese, and the islands Kithira, Antikithira and Gavdos. Southern Aegean Sea, featuring the Southern Hellenic Arc (HA) of the Hellenic Subduction Zone (HSZ) and the Hellenic Volcanic Arc (HVA), depicts complex geotectonics and the most intense seismicity and geodynamics of Western Eurasia. In this work we summarize the most important results of the MT and TEM combined analysis and modelling. Furthermore, two permanent telemetric MT stations were installed and operated in Western Crete and Rhodes, respectively, to be used as remote reference and to investigate possible transient seismoelectromagnetic signals. The case of the October 12, 2013 strong earthquake (Mb6.4) is discussed. The research was conducted in the framework of the project entitled "MagnetoTellurics in studying Geodynamics of the hEllenic Arc (MT-GEAR)", co-funded by the European Social Fund (ESF) and National Resources within the context of the Action "Supporting Postdoctoral Researchers" of the Operational Programme 'Education and Lifelong Learning'.

  8. Trichoptera biodiversity of the Aegean and Adriatic sea basins in the republic of Kosovo.

    PubMed

    Ibrahimi, Halil; Kučinić, Mladen; Gashi, Agim; Grapci-Kotori, Linda

    2014-01-01

    We present the first preliminary inventory of Trichoptera taxa in the Aegean and Adriatic Sea basins in Kosovo that have previously received poor and fragmentary attention. Adult caddisflies were collected using ultraviolet (UV) light traps in 13 stations in areas of the Aegean Sea and Adriatic Sea drainage basins in Kosovo. Nineteen species out of 82, reported in this article, are first records for the Kosovo caddisfly fauna. Five genera are recorded for the first time in Kosovo: Brachycentrus, Ecclisopteryx, Psilopteryx, Thremma, and Oecetis. During this investigation, we found several Southeastern European endemic and rare species whose previous known distribution was limited to particular areas of this region, as well as other species whose distribution is considerably enlarged by this investigation: Polycentropus ierapetra, Polycentropus irroratus, Chaetopteryx stankovici, Drusus schmidi, Drusus tenellus, Potamophylax goulandriourum, Oecetis notata, and Notidobia melanoptera. Even though this article is a result of a limited sampling effort, it increases the number of Trichoptera taxa recorded for the Republic of Kosovo to 131.

  9. Particulate and dissolved primary production along a pronounced hydrographic and trophic gradient (Turkish Straits System-NE Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Lagaria, A.; Psarra, S.; Gogou, A.; Tuğrul, S.; Christaki, U.

    2013-06-01

    The rates of particulate (PPp) and dissolved primary production (PPd) were estimated along a trajectory of variable environmental regimes formed in a narrow shelf area, following the course of Black Sea water masses (BSW) passing through the Turkish Straits System (TSS) into the NE Aegean Sea (BS-AS outflow). Seven stations in total were sampled, covering a transect from the eastern edge of the Marmara Sea basin to the NE Aegean Sea, during two consecutive cruises performed in October 2008 within the framework of the EU SESAME project. Along the BS-AS outflow, depth-integrated over the surface BSW layer PPp decreased considerably from 91 to < 16 mg C m- 2 h- 1 whereas PPd increased from 3 to 10 mg C m- 2 h- 1. As a consequence, the relative importance of PPd over total production (percentage extracellular release, PER) increased from 6% (± 3% sd) in the Marmara Sea to 37% (± 4% sd) in the NE Aegean Sea. Total chlorophyll a concentration gradually decreased and phytoplankton community size-structure was modified, with pico-phytoplankton, that originally represented 35% (± 9% sd) in the Marmara Sea, gradually becoming dominant in the NE Aegean (77% ± 2% sd), substituting large nano- and micro-phytoplankton cells (> 5 μm). This study showed that PER increased along a gradient from mesotrophy to oligotrophy, probably due to nutrient deficiency constraining phytoplankton growth and was closely related to phytoplankton size-structure. In the oligotrophic NE Aegean Sea, phytoplankton exudation was a significant source of dissolved organic carbon for heterotrophic prokaryotes.

  10. 8 January 2013 Mw=5.7 North Aegean Sea Earthquake Sequence

    NASA Astrophysics Data System (ADS)

    Kürçer, Akın; Yalçın, Hilal; Gülen, Levent; Kalafat, Doǧan

    2014-05-01

    The deformation of the North Aegean Sea is mainly controlled by the westernmost segments of North Anatolian Fault Zone (NAFZ). On January 8, 2013, a moderate earthquake (Mw= 5.7) occurred in the North Aegean Sea, which may be considered to be a part of westernmost splay of the NAFZ. A series of aftershocks were occurred within four months following the mainschock, which have magnitudes varying from 1.9 to 5.0. In this study, a total of 23 earthquake moment tensor solutions that belong to the 2013 earthquake sequence have been obtained by using KOERI and AFAD seismic data. The most widely used Gephart & Forsyth (1984) and Michael (1987) methods have been used to carry out stress tensor inversions. Based on the earthquake moment tensor solutions, distribution of epicenters and seismotectonic setting, the source of this earthquake sequence is a N75°E trending pure dextral strike-slip fault. The temporal and spatial distribution of earthquakes indicate that the rupture unilaterally propagated from SW to NE. The length of the fault has been calculated as approximately 12 km. using the afterschock distribution and empirical equations, suggested by Wells and Coppersmith (1994). The stress tensor analysis indicate that the dominant faulting type in the region is strike-slip and the direction of the regional compressive stress is WNW-ESE. The 1968 Aghios earthquake (Ms=7.3; Ambraseys and Jackson, 1998) and 2013 North Aegean Sea earthquake sequences clearly show that the regional stress has been transferred from SW to NE in this region. The last historical earthquake, the Bozcaada earthquake (M=7.05) had been occurred in the northeast of the 2013 earthquake sequence in 1672. The elapsed time (342 year) and regional stress transfer point out that the 1672 earthquake segment is probably a seismic gap. According to the empirical equations, the surface rupture length of the 1672 Earthquake segment was about 47 km, with a maximum displacement of 170 cm and average displacement

  11. New discovery and geological significance of Late Silurian-Carboniferous extensional structures in Tarim Basin

    NASA Astrophysics Data System (ADS)

    Li, Yue-Jun; Wen, Lei; Yang, Hai-Jun; Zhang, Guang-Ya; Shi, Jun; Peng, Geng-Xin; Hu, Jian-Feng; Luo, Jun-Cheng; Huang, Zhi-Bin; Chen, Yan-Gui; Zhang, Qiang

    2015-02-01

    Late Silurian-Carboniferous extensional structures have been discovered after careful interpretation of seismic reflection data in western Manjiaer Sag, Central Tarim Basin in central Asia. The extensional structures comprise numerous small normal faults in nearly N-S strike direction. Groups of normal faults in profile show features suggestive of negative flower structures and small horst-graben structures. Based on growth index calculation, these extensional structures formed in the Late Silurian period, continued activity in the Devonian and Carboniferous and then ceased at the end of Carboniferous. The peak-stage of normal fault activity occurred in Late Silurian. Late Silurian-Carboniferous normal faults also developed in the Tazhong and Tabei areas, which implies that Tarim Basin were under regional extensional tectonic setting during that periods. The extensional structure in southern Tarim resulted from the post-orogeny stress relaxation of the Kunlun Early Paleozoic orogenic belt, and those in northern Tarim resulted from the Paleozoic back-arc rifting which led to the opening of South Tianshan ocean.

  12. Biodiversity of zoobenthic hard-substrate sublittoral communities in the Eastern Mediterranean (North Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Antoniadou, Chryssanthi; Chintiroglou, Chariton

    2005-03-01

    The spatial dispersion of zoobenthos from sublittoral hard substrate communities in the northern part of the Aegean Sea has been studied during summer 1997 and 1998. Material was collected by SCUBA diving, by totally scraping off five replicate quadrates (400 cm 2 each) at three depth levels (15, 30, 40 m) from six sites located in Chalkidiki peninsula, plus one in Kavala Gulf. The examination of the 19,343 living specimens collected revealed the presence of 314 species. Though the multivariate analyses showed high similarity between stations, the structure of this sciaphilic algal community seems to have an increased spatial heterogeneity. Four distinct facies were recorded in accordance with the occurrence of different algal forms, the degree of hard substrate inclination and the water clarity. A short review on the biodiversity of sublittoral communities in the Mediterranean revealed the affinity between the western and the eastern basin and also among the photophilic and the sciaphilic algal communities.

  13. Performance of Statistical Temporal Downscaling Techniques of Wind Speed Data Over Aegean Sea

    NASA Astrophysics Data System (ADS)

    Gokhan Guler, Hasan; Baykal, Cuneyt; Ozyurt, Gulizar; Kisacik, Dogan

    2016-04-01

    Wind speed data is a key input for many meteorological and engineering applications. Many institutions provide wind speed data with temporal resolutions ranging from one hour to twenty four hours. Higher temporal resolution is generally required for some applications such as reliable wave hindcasting studies. One solution to generate wind data at high sampling frequencies is to use statistical downscaling techniques to interpolate values of the finer sampling intervals from the available data. In this study, the major aim is to assess temporal downscaling performance of nine statistical interpolation techniques by quantifying the inherent uncertainty due to selection of different techniques. For this purpose, hourly 10-m wind speed data taken from 227 data points over Aegean Sea between 1979 and 2010 having a spatial resolution of approximately 0.3 degrees are analyzed from the National Centers for Environmental Prediction (NCEP) The Climate Forecast System Reanalysis database. Additionally, hourly 10-m wind speed data of two in-situ measurement stations between June, 2014 and June, 2015 are considered to understand effect of dataset properties on the uncertainty generated by interpolation technique. In this study, nine statistical interpolation techniques are selected as w0 (left constant) interpolation, w6 (right constant) interpolation, averaging step function interpolation, linear interpolation, 1D Fast Fourier Transform interpolation, 2nd and 3rd degree Lagrange polynomial interpolation, cubic spline interpolation, piecewise cubic Hermite interpolating polynomials. Original data is down sampled to 6 hours (i.e. wind speeds at 0th, 6th, 12th and 18th hours of each day are selected), then 6 hourly data is temporally downscaled to hourly data (i.e. the wind speeds at each hour between the intervals are computed) using nine interpolation technique, and finally original data is compared with the temporally downscaled data. A penalty point system based on

  14. Concentration of heavy metals in seawater and sediments from the northern Aegean Sea, Greece

    SciTech Connect

    Fytianos, K; Vasilikiotis, G.S.

    1983-01-01

    The aim of the study presented was to investigate the distribution of heavy metals in seawater and sediments in areas, which face increasing marine pollution problems, due to the industrialization and especially in the closed gulfs of Thermaikos and Kavala in north Aegean sea. The city of Thessaloniki with more than 1,200,000 inhabitants and the surrounding industrial area use Thermaikos Gulf as the final receiver for their liquid wastes. The Gulf of Thermaikos receives domestic, agricultural, industrial and natural runoff from a heavily populated and fairly industrialized area. The heavy metal contamination is mainly affected by industrial wastes from oil refinery, steel industry, a fertilizer plant and some other industries located in the industrial area, west of the city.

  15. Metal levels in sediments and transplanted mussels in Pagassitikos Gulf (Aegean Sea, Eastern Mediterranean).

    PubMed

    Tsangaris, Catherine; Kaberi, Helen; Catsiki, Vassiliki-Angelique

    2013-07-01

    Metal concentrations were determined in surface sediments and transplanted mussels in a shallow semi-enclosed bay, Pagassitikos Gulf, Aegean Sea. Cu, Zn, Pb, Hg, and As levels in sediments were enriched close to point sources of pollution, i.e., Volos Port and cement plant. Fe, Mn, Cr, and Ni spatial distributions in sediments were rather uniform with increasing concentrations towards deeper sites, suggesting natural enrichment, whereas levels found in the port, although elevated, were not the highest in the study area. Spatial variations in concentrations of most metals in mussels transplanted nearshore were generally in accordance to those in sediments, with the highest Fe, Mn, Cr, Ni, and Cu levels in the port and the highest Hg levels close to the cement plant. Concentrations of metals in sediments and transplanted mussels were comparable to those reported in Mediterranean areas. Results indicate that pollution point sources contribute to anthropogenic metal enrichment in the study area.

  16. The Aegean in the Early 7th Millennium BC: Maritime Networks and Colonization.

    PubMed

    Horejs, B; Milić, B; Ostmann, F; Thanheiser, U; Weninger, B; Galik, A

    The process of Near Eastern neolithization and its westward expansion from the core zone in the Levant and upper Mesopotamia has been broadly discussed in recent decades, and many models have been developed to describe the spread of early farming in terms of its timing, structure, geography and sociocultural impact. Until now, based on recent intensive investigations in northwestern and western Anatolia, the discussion has mainly centred on the importance of Anatolian inland routes for the westward spread of neolithization. This contribution focuses on the potential impact of east Mediterranean and Aegean maritime networks on the spread of the Neolithic lifestyle to the western edge of the Anatolian subcontinent in the earliest phases of sedentism. Employing the longue durée model and the concept of 'social memory', we will discuss the arrival of new groups via established maritime routes. The existence of maritime networks prior to the spread of farming is already indicated by the high mobility of Epipalaeolithic/Mesolithic groups exploring the Aegean and east Mediterranean seas, and reaching, for example, the Cyclades and Cyprus. Successful navigation by these early mobile groups across the open sea is attested by the distribution of Melian obsidian. The potential existence of an additional Pre-Pottery Neolithic (PPN) obsidian network that operated between Cappadocia/Cilicia and Cyprus further hints at the importance of maritime coastal trade. Since both the coastal and the high seas networks were apparently already well established in this early period, we may further assume appropriate knowledge of geographic routes, navigational technology and other aspects of successful seafaring. This Mesolithic/PPN maritime know-how package appears to have been used by later groups, in the early 7th millennium calBC, exploring the centre of the Anatolian Aegean coast, and in time establishing some of the first permanent settlements in that region. In the present paper, we

  17. Macrofauna biodiversity of mussel bed assemblages in Thermaikos Gulf (northern Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Chintiroglou, Chariton-Charles; Damianidis, Panagiotis; Antoniadou, Chryssanthi; Lantzouni, Marina; Vafidis, Dimitris

    2004-02-01

    Biomonitoring of mussel bed assemblages can provide valuable information about the impact of pollution on hard substrate assemblages. This study of Mytilus galloprovincialis mussel beds in Thermaikos Gulf (northern Aegean Sea) deals with the spatial and temporal structure of the associated fauna. Samples were collected and abiotic factors were measured in two successive years. Common biocoenotic methods were employed to analyze the data. The samples could be separated into three groups, with summer and winter samples being clearly different. A total of 100 species were found: polychaetes and crustaceans were the most dominant taxa. The assemblage shows high diversity with respect to species abundance. Biotic interactions within the assemblage appear to influence its composition, although the total evenness remains unaffected in space and time. The M. galloprovincialis assemblages can be found in clean as well as in polluted waters and, therefore, are of great interest in biomonitoring studies.

  18. Operational monitoring and forecasting in the Aegean Sea: system limitations and forecasting skill evaluation.

    PubMed

    Nittis, K; Zervakis, V; Perivoliotis, L; Papadopoulos, A; Chronis, G

    2001-01-01

    The POSEIDON system, based on a network of 11 oceanographic buoys and a system of atmospheric/oceanic models, provides real-time observations and forecasts of the marine environmental conditions in the Aegean Sea. The buoy network collects meteorological, sea state and upper-ocean physical and biochemical data. The efficiency and functionality of the various system components are being evaluated during the present pre-operational phase and discussed in this paper. The problem of bio-fouling on optical and chemical sensors is found to be a main limitation factor on the quality of data. Possible solutions to this problem as well as quality control methods that are being developed are also described. Finally, an evaluation of the numerical models is presented through the estimation of their forecasting skill for selected periods.

  19. Exploration of the Black, Aegean, and Mediterranean Seas Aboard E/V Nautilus

    NASA Astrophysics Data System (ADS)

    Bell, K. L.; Ballard, R. D.; Brennan, M. L.; Raineault, N. A.; Shank, T. M.; Mayer, L. A.; Roman, C.; Mitchell, G. A.; Coleman, D. F.

    2012-12-01

    In the summer of 2012, the Exploration Vessel (E/V) Nautilus undertook a two-month expedition to the Black, Aegean, and Mediterranean Seas. The primary goal of the Nautilus is to create a focus of international leadership for the development and integration of leading-edge technologies, educational programs, field operations, and public outreach programs for ocean exploration, in partnership with the NOAA Office of Ocean Exploration, National Geographic Society, Office of Naval Research, and corporate partners. To do so, the program uses a complement of deep submergence vehicle systems and telepresence technologies to engage scientists, educators and the public, both at sea and ashore, allowing them to become integral members of the on-board exploration team. When discoveries are made, experts ashore are notified and brought aboard virtually within a short period of time to help guide shipboard response before the ship moves on. The 2012 expedition is comprised of four areas of interest. Extensive sidescan mapping took place off the Turkish coasts of the southern Black Sea and eastern Aegean Sea, and was followed by remotely operated vehicle (ROV) dives on targets of archaeological, geological, and biological interest. In the Black Sea, additional work was done on the porewater chemistry of the sediments in the oxic, suboxic, and anoxic zones. Nautilus returned to the Anaximander Seamounts, including Kazan, Amserdam, Thessaloniki, and Athina, to further explore active and formerly active seep sites located in 2010. Finally, based on biological and geological discoveries made on Eratosthenes Seamount in the eastern Mediterranean Sea, we returned to further study chemosynthetic vent communities and tectonic processes.;

  20. Progress of KOERI Tsunami Warning System for the Eastern Mediterranean, Aegean and Black Seas

    NASA Astrophysics Data System (ADS)

    Necmioglu, Ocal; Meral Ozel, Nurcan; Ozer Sozdinler, Ceren; Yilmazer, Mehmet; Cokacar, Tulay; Comoglu, Mustafa; Pinar, Ali; Kekovali, Kivanc

    2016-04-01

    This presentation provides a progress report on the activities of the Bogazici University / Kandilli Observatory and Earthquake Research Institute - Regional Earthquake and Tsunami Monitoring Center (KOERI-RETMC) which provides services as a Candidate Tsunami Service Provider (CTSP) of ICG/NEAMTWS in the Eastern Mediterranean, Aegean and Black Seas since 1 July 2012. KOERI continues to operate 178 BB and 97 strong motion and 6 short period sensors and the regional coverage includes 77 stations from GFZ and additional 16 stations through bilateral agreements. One radar-type tide-gauge has been installed in Fethiye within the framework of "Inexpensive Device for Sea-Level Measurement" (IDSL) initiative offered as donation by the EC/JRC and planning is in progress for the possible installation of three more IDSLs in selected locations in the Aegean Sea coast of Turkey. The capabilities and the limitations of HF Radar technology for the purpose of tsunami detection in the Eastern Mediterranean has been identified and the maturity and the applicability of these systems for the possible use under the Tsunami Warning System has been determined. The development of the TsuComp as a user-friendly interface to be used in the assessment of tsunamigenic potential and as a single-point entry for message dissemination has been finalized. The work towards the creation of Tsunami Inundation Maps at the Tsunami Forecast Points in Turkey is near finalization. This work is partially funded by project ASTARTE - Assessment, Strategy And Risk Reduction for Tsunamis in Europe - FP7-ENV2013 6.4-3, Grant 603839. The authors would like to thank EC/JRC and Mr. Alessandro Annunziato for their continuous support in the operational activities of RETMC and IDSL initiative.

  1. Styela plicata: a new promising bioindicator of heavy metal pollution for eastern Aegean Sea coastal waters.

    PubMed

    Aydın-Önen, S

    2016-11-01

    As part of a research project, the concentrations of Cd, Cu, Pb, V, and Zn in the tissues of Styela plicata were investigated for the first time to determine if S. plicata is a suitable biological indicator for biomonitoring of heavy metals in eastern Aegean Sea coastal waters. To examine the relationships, heavy metal levels in suspended particulate matters (SPMs) and sediments were also determined. According to the results, the mean metal levels in SPM, sediments, and S. plicata samples could be arranged in the following order of abundance: Zn > Cu > Pb > V > Cd. As for heavy metal levels, significant positive correlations were noted between Cd-Pb, Cd-V, Cd-Zn, Cu-V, and Pb-V in SPM; Cd-Zn, Cu-Zn, Pb-Cd, Pb-Cu, and Pb-Zn in sediment; and Cu-Pb, Cu-Zn, and Pb-Zn in S. plicata samples. Positive relationships between these metals showed that they were originated from same sources and that they were associated with each other. Based on the findings, Zn, Cu, and Pb concentrations in suspended particulate matters, sediments, and S. plicata samples were generally represented with higher levels at stations that were used for boating, shipping, and related activities. As S. plicata is a strongest accumulator of V, the relatively low V levels observed in this study may indicate the lack of anthropogenic sources of this metal in the sampling stations. In conclusion, suspended particulate matter and sediment can be useful tool to detect the pollution status of the marine environment. Furthermore, the findings of this study highlighted that S. plicata is a promising alternative for the monitoring of heavy metal pollution for eastern Aegean Sea coasts.

  2. Centennial-scale paleoceanography during sapropel S1 deposition in the NE Aegean (Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Triantaphyllou, Maria; Gogou, Alexandra; Dimiza, Margarita; Kostopoulou, Sofia; Parinos, Constantine; Roussakis, Grigoris; Geraga, Maria; Skampa, Elisavet; Bouloubassi, Ioanna; Fleitmann, Dominik; Zervakis, Vassilis; Velaoras, Dimitris; Diamantopoulou, Antonia; Sampatakaki, Angeliki; Lykousis, Vassilis

    2016-04-01

    Combined micropaleontological and geochemical analyses in the high-sedimentation gravity core M-4G, provided new centennial scale paleoceanographic data for the sapropel S1 deposition in the NE Aegean Sea. Sapropel layer S1a (10.2-8.0 ka) is deposited in dysoxic to oxic bottom waters; sediments are characterized by the high abundance of benthic foraminifers Chilostomella mediterranensis and Globobulimina affinis that are able to tolerate surface sediment and/or pore water oxygen depletion and the presence of the oxic mesotrophic-eutrophic U. mediterranea. Adequate preservation of organic matter is proven by the high organic carbon and loliolide and isololiolide contents, whereas the biomarker record and the abundances of eutrophic planktonic foraminifera document enhanced productivity. Both alkenone-based SSTs and δO18 G. bulloides records indicate coolings at 8.2 ka (S1a) and at ~7.8 ka (S1 interruption). Sapropelic layer S1b (7.7-6.4 ka) is characterized by rather oxic conditions marked by the prominent increase of U. mediterranea. The highly fluctuating SSTs demonstrate repeated coolings and associated dense water formation; major event at 7.4 ka, followed by cold spells at 7.0, 6.8, 6.5 ka. Besides, the increase of algal biomarkers, labile organic matter-feeding foraminifera and eutrophic planktonic species pinpoints rise in in situ marine productivity, which is enhanced by more efficient vertical convection due to repeated cold events. The associated contributions of labile marine organic matter (OM) along with fresher terrestrial OM inputs after ~7.7 ka BP imply alternative/ additional than the north Aegean riverine borderland sources for the influx of organic matter at the south Limnos Basin, also related to the inflow of highly productive Marmara/Black Sea waters

  3. New Constraints on Extensional Environments through Analysis of Teleseisms

    NASA Astrophysics Data System (ADS)

    Eilon, Zachary Cohen

    We apply a variety of teleseismic methodologies to investigate the upper mantle structure in extensional environments. Using a body wave dataset collected from a regional deployment in the Woodlark Rift, Papua New Guinea, we image anisotropic velocity structure of a rapidly extending rift on the cusp of continental breakup. In the process, we develop a technique for azimuthal anisotropy tomography that is generally applicable to regions of relatively simple anisotropic structure. The Cascadia Initiative ocean bottom seismometer (OBS) deployment provides coverage of an entire oceanic plate in unprecedented detail; we measure attenuation and velocities of teleseisms to characterize the temperature and melt structure from ridge to trench. Our study of shear wave splitting reveals strong azimuthal anisotropy within the Woodlark Rift with fairly uniform fast directions parallel to extension. This observation differs markedly from other continental rifts and resembles the pattern seen at mid-ocean ridges. This phenomenon is best explained by extension-related strain causing preferential alignment of mantle olivine. We develop a simple relationship that links total extension to predicted splitting, and show that it explains the apparent dichotomy in rifts' anisotropy. Finite frequency tomography using a dataset of teleseismic P- and S-wave differential travel times reveals the upper mantle velocity structure of the Woodlark Rift. A well developed slow rift axis extending >250 km along strike from the adjacent seafloor spreading centers demonstrates the removal of mantle lithosphere prior to complete crustal breakup. We argue that the majority of this rift is melt-poor, in agreement with geochemical results. A large temperature gradient arises from the juxtaposition of upwelled axial asthenosphere with a previously unidentified cold structure north of the rift that hosts well located intermediate depth earthquakes. Localization of upper mantle extension is apparent from

  4. Climate variability and socio-environmental changes in the northern Aegean (NE Mediterranean) during the last 1500 years

    NASA Astrophysics Data System (ADS)

    Gogou, Alexandra; Triantaphyllou, Maria; Xoplaki, Elena; Izdebski, Adam; Parinos, Constantine; Dimiza, Margarita; Bouloubassi, Ioanna; Luterbacher, Juerg; Kouli, Katerina; Martrat, Belen; Toreti, Andrea; Fleitmann, Dominik; Rousakis, Gregory; Kaberi, Helen; Athanasiou, Maria; Lykousis, Vasilios

    2016-04-01

    We provide new evidence on sea surface temperature (SST) variations and paleoceanographic/paleoenvironmental changes over the past 1500 years for the north Aegean Sea (NE Mediterranean). The reconstructions are based on multiproxy analyses, obtained from the high resolution (decadal to multi-decadal) marine record M2 retrieved from the Athos basin. Reconstructed SSTs show an increase from ca. 850 to 950 AD and from ca. 1100 to 1300 AD. A cooling phase of almost 1.5 °C is observed from ca. 1600 AD to 1700 AD. This seems to have been the starting point of a continuous SST warming trend until the end of the reconstructed period, interrupted by two prominent cooling events at 1832 ± 15 AD and 1995 ± 2 AD. Application of an adaptive Kernel smoothing suggests that the current warming in the reconstructed SSTs of the north Aegean might be unprecedented in the context of the past 1500 years. Internal variability in atmospheric/oceanic circulations systems as well as external forcing as solar radiation and volcanic activity could have affected temperature variations in the north Aegean Sea over the past 1500 years. The marked temperature drop of approximately ~2°C at 1832 ± 15 yr AD could be related to the 1809 ΑD 'unknown' and the 1815 AD Tambora volcanic eruptions. Paleoenvironmental proxy-indices of the M2 record show enhanced riverine/continental inputs in the northern Aegean after ca. 1450 AD. The palaeoclimatic evidence derived from M2 record is combined with a socio-environmental study of the history of the north Aegean region. We show that the cultivation of temperature-sensitive crops, i.e. walnut, vine and olive, co-occurred with stable and warmer temperatures, while its end coincided with a significant episode of cooler temperatures. Periods of agricultural growth in Macedonia coincide with periods of warmer and more stable SSTs, but further exploration is required in order to identify the causal links behind the observed phenomena. The Black Death likely

  5. Climate variability and socio-environmental changes in the northern Aegean (NE Mediterranean) during the last 1500 years

    NASA Astrophysics Data System (ADS)

    Gogou, Alexandra; Triantaphyllou, Maria; Xoplaki, Elena; Izdebski, Adam; Parinos, Constantine; Dimiza, Margarita; Bouloubassi, Ioanna; Luterbacher, Juerg; Kouli, Katerina; Martrat, Belen; Toreti, Andrea; Fleitmann, Dominik; Rousakis, Gregory; Kaberi, Helen; Athanasiou, Maria; Lykousis, Vasilios

    2016-03-01

    We provide new evidence on sea surface temperature (SST) variations and paleoceanographic/paleoenvironmental changes over the past 1500 years for the north Aegean Sea (NE Mediterranean). The reconstructions are based on multiproxy analyses, obtained from the high resolution (decadal to multi-decadal) marine record M2 retrieved from the Athos basin. Reconstructed SSTs show an increase from ca. 850 to 950 AD and from ca. 1100 to 1300 AD. A cooling phase of almost 1.5 °C is observed from ca. 1600 AD to 1700 AD. This seems to have been the starting point of a continuous SST warming trend until the end of the reconstructed period, interrupted by two prominent cooling events at 1832 ± 15 AD and 1995 ± 1 AD. Application of an adaptive Kernel smoothing suggests that the current warming in the reconstructed SSTs of the north Aegean might be unprecedented in the context of the past 1500 years. Internal variability in atmospheric/oceanic circulations systems as well as external forcing as solar radiation and volcanic activity could have affected temperature variations in the north Aegean Sea over the past 1500 years. The marked temperature drop of approximately ∼2 °C at 1832 ± 15 yr AD could be related to the 1809 ΑD 'unknown' and the 1815 AD Tambora volcanic eruptions. Paleoenvironmental proxy-indices of the M2 record show enhanced riverine/continental inputs in the northern Aegean after ca. 1450 AD. The paleoclimatic evidence derived from the M2 record is combined with a socio-environmental study of the history of the north Aegean region. We show that the cultivation of temperature-sensitive crops, i.e. walnut, vine and olive, co-occurred with stable and warmer temperatures, while its end coincided with a significant episode of cooler temperatures. Periods of agricultural growth in Macedonia coincide with periods of warmer and more stable SSTs, but further exploration is required in order to identify the causal links behind the observed phenomena. The Black Death

  6. Comparison between extensional rheological properties of low density polyethylene melt in SER and RME rheometric systems

    NASA Astrophysics Data System (ADS)

    Narimissa, Esmaeil; Rolón-Garrido, Víctor Hugo; Wagner, Manfred Hermann

    2015-04-01

    Precise evaluation and notional prediction of extensional rheological behaviour of polymeric melts and solutions are of significant importance in polymer industry. This is evident in the well documentation of the dominance of elongational deformation of polymeric systems in processes such as melt spinning, blow moulding, biaxial stretching of extruded sheets, etc. The relevant commercial extensional rheometers thus far discussed in the literature are RME and SER. This research, for the first time, compares the extensional viscosity measurements of low density polyethylene at 140, 150, and 170 °C through RME and SER devices. Despite the observed similarities found in this comparative investigation, the main difference was laid in maximum Hencky strain, strain hardening viscosity, and the variation of those rheological properties with testing temperature of the samples.

  7. Nonlinear coupling of flexural mode and extensional bulk mode in micromechanical resonators

    NASA Astrophysics Data System (ADS)

    Zhang, Tianyi; Ren, Juan; Wei, Xueyong; Jiang, Zhuangde; Huan, Ronghua

    2016-11-01

    The effect of coupling between the extensional bulk mode and the flexural mode of a cantilever beam resonator has been experimentally studied by exciting the two modes simultaneously. The modal frequency shift of linear extensional bulk mode shows a quadratic relationship with the square of flexural mode's amplitude displacement, and a frequency shift up to 1492 Hz is observed when the flexural mode is driven by a AC signal Vac of 3 V and a DC bias of 30 V. The flexural mode shows a Duffing-like behavior with a softening nonlinearity and its frequency shift is influenced not only by its own nonlinear amplitude-frequency effect but also the extensional mode's amplitude as predicted. The nonlinear coupling coefficient is found to be about two orders of magnitude larger than the softening nonlinearity.

  8. Extensional fault uplift of regional Franciscan blueschists due to subduction shallowing during the Laramide orogeny

    SciTech Connect

    Krueger, S.W.; Jones, D.L. )

    1989-12-01

    Regional structural and stratigraphic relations in the northern California Coast Ranges require an episode of extensional tectonic unroofing of coherent blueschist terranes of the Eastern belt of the Franciscan complex along a crustal-scale, low-angle, normal-fault system, here named the Cost Range detachment. This tectonic unroofing occurred during the latest Cretaceous and early Tertiary, contemporaneous with the compressional Laramide orogeny of the North American interior. Dynamic models of accretionary wedges predict that shallowing of subduction, as has been inferred during the Laramide orogeny, will impart extensional stresses in the wedge above the subducting plate. The authors therefore suggest a single casual event--gradual shallowing of subduction in the latest Cretaceous and early Tertiary--to link the extensional fault uplift of regional Franciscan blueschists to Laramide compression in the North American interior.

  9. Spatial and temporal relations between coronae and extensional belts, northern Lada Terra, Venus

    NASA Astrophysics Data System (ADS)

    Baer, G.; Schubert, G.; Bindschadler, D. L.; Stofan, E. R.

    1994-04-01

    Preliminary studies of the distribution of coronae and volcanic rises on Venus show that many of these features tend to cluster along zones of rifting and extension. The plains north of Lada Terra are crossed by two such extensional belts. Each belt is composed of grabens, ridges, faults, volcanic flows, coronae and coronalike features. The longer and more prominent belt is the NW trending Alpha-Lada extensional belt, which is over 6000 km long and 50-200 km wide, and includes the coronae Eve, Tamfana, Carpo, Selu, Derceto, Otygen, and an unnamed corona south of Otygen. The second belt is the NNE trending Derceto-Quetzalpetlatl extensional belt, which is about 2000 km long and in places over 300 km wide, and includes the coronae Sarpanitum, Eithinoha, and Quetzalpetlatl. The two belts intersect at the 1600 x 600 km wide Derceto volcanic plateau. It is apparent that deformation along the two belts overlapped in time, though deformation along the Alpha-Lada extensional belt probably continued after the deformation along the Derceto-Quetzalpetlatl extensional belt terminated. In certain areas, volcanism originated in grabens within the extensional belts, whereas in other areas, such as in Eve, Selu, Derceto, and Quetzalpetlatl, volcanism originated in the coronae and flowed into the lower parts of the extensional belts. Regional extension has affected the evolution of all the coronae at some stage of their development. Regional deformation occurred before the initiation of Derceto and Eithinoha of their development. Regional deformation occurred before the initiation of Derceto and Eithinoha and after the initiation of Carpo, Tamfana, Otygen, and Sarpanitum. It is thus unlikely that coronae formation along the belts is solely a consequence of the regional extension, and it is also unlikely that regional extension has been caused solely by the coronae. No corona along the belts was formed subsequent to the cessation of the regional extension. We therefore suggest that

  10. Effects of extensional rates on characteristic scales of two-dimensional turbulence in polymer solutions

    NASA Astrophysics Data System (ADS)

    Hidema, R.

    2014-08-01

    In order to study the effects of extensional viscosities on turbulent drag reduction, experimental studies using two-dimensional turbulence have been made. Anisotropic structures and variations of energy transfer induced by polymers are considered. Polyethyleneoxide and hydroxypropyl cellulose having different flexibility, which is due to different characteristics of extensional viscosity, are added to 2D turbulence. Variations of the turbulence were visualized by interference patterns of 2D flow, and were analysed by an image processing. The effects of polymers on turbulence in the streamwise and normal directions were also analysed by 2D Fourier transform. In addition, characteristic scales in 2D turbulence were analysed by wavelet transform.

  11. Spatial and temporal relations between coronae and extensional belts, northern Lada Terra, Venus

    NASA Technical Reports Server (NTRS)

    Baer, Gidon; Schubert, Gerald; Bindschadler, Duane L.; Stofan, Ellen R.

    1994-01-01

    Preliminary studies of the distribution of coronae and volcanic rises on Venus show that many of these features tend to cluster along zones of rifting and extension. The plains north of Lada Terra are crossed by two such extensional belts. Each belt is composed of grabens, ridges, faults, volcanic flows, coronae and coronalike features. The longer and more prominent belt is the NW trending Alpha-Lada extensional belt, which is over 6000 km long and 50-200 km wide, and includes the coronae Eve, Tamfana, Carpo, Selu, Derceto, Otygen, and an unnamed corona south of Otygen. The second belt is the NNE trending Derceto-Quetzalpetlatl extensional belt, which is about 2000 km long and in places over 300 km wide, and includes the coronae Sarpanitum, Eithinoha, and Quetzalpetlatl. The two belts intersect at the 1600 x 600 km wide Derceto volcanic plateau. It is apparent that deformation along the two belts overlapped in time, though deformation along the Alpha-Lada extensional belt probably continued after the deformation along the Derceto-Quetzalpetlatl extensional belt terminated. In certain areas, volcanism originated in grabens within the extensional belts, whereas in other areas, such as in Eve, Selu, Derceto, and Quetzalpetlatl, volcanism originated in the coronae and flowed into the lower parts of the extensional belts. Regional extension has affected the evolution of all the coronae at some stage of their development. Regional deformation occurred before the initiation of Derceto and Eithinoha of their development. Regional deformation occurred before the initiation of Derceto and Eithinoha and after the initiation of Carpo, Tamfana, Otygen, and Sarpanitum. It is thus unlikely that coronae formation along the belts is solely a consequence of the regional extension, and it is also unlikely that regional extension has been caused solely by the coronae. No corona along the belts was formed subsequent to the cessation of the regional extension. We therefore suggest that

  12. Evolutionary processes in a continental island system: molecular phylogeography of the Aegean Nigella arvensis alliance (Ranunculaceae) inferred from chloroplast DNA.

    PubMed

    Bittkau, C; Comes, H P

    2005-11-01

    Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of past fragmentation, dispersal, and genetic drift on taxon diversification. We used phylogeographical (nested clade) and population genetic analyses to elucidate the relative roles of these processes in the evolutionary history of the Aegean Nigella arvensis alliance (= 'coenospecies'). We surveyed chloroplast DNA (cpDNA) variation in 455 individuals from 47 populations (nine taxa) of the alliance throughout its core range in the Aegean Archipelago and surrounding mainland areas of Greece and Turkey. The study revealed the presence of three major lineages, with largely nonoverlapping distributions in the Western, Central, and Eastern Aegean. There is evidence supporting the idea that these major lineages evolved in situ from a widespread (pan-Aegean) ancestral stock as a result of multiple fragmentation events, possibly due to the influence of post-Messinian sea flooding, Pleistocene eustatic changes and corresponding climate fluctuations. Over-sea dispersal and founder events appear to have played a rather insignificant role in the group's history. Rather, all analytical approaches identified the alliance as an organism group with poor seed dispersal capabilities and a susceptibility to genetic drift. In particular, we inferred that the observed level of cpDNA differentiation between Kikladian island populations of Nigella degenii largely reflects population history, (viz. Holocene island fragmentation) and genetic drift in the near absence of seed flow since their time of common ancestry. Overall, our cpDNA data for the N. arvensis alliance in general, and N. degenii in particular, indicate that historical events were important in determining the phylogeographical patterns seen, and that genetic drift has historically been relatively more influential on population structure than has cytoplasmic gene flow.

  13. Towards an absolute chronology for the Aegean iron age: new radiocarbon dates from Lefkandi, Kalapodi and Corinth.

    PubMed

    Toffolo, Michael B; Fantalkin, Alexander; Lemos, Irene S; Felsch, Rainer C S; Niemeier, Wolf-Dietrich; Sanders, Guy D R; Finkelstein, Israel; Boaretto, Elisabetta

    2013-01-01

    The relative chronology of the Aegean Iron Age is robust. It is based on minute stylistic changes in the Submycenaean, Protogeometric and Geometric styles and their sub-phases. Yet, the absolute chronology of the time-span between the final stages of Late Helladic IIIC in the late second millennium BCE and the archaic colonization of Italy and Sicily toward the end of the 8(th) century BCE lacks archaeological contexts that can be directly related to events carrying absolute dates mentioned in Egyptian/Near Eastern historical sources, or to well-dated Egyptian/Near Eastern rulers. The small number of radiocarbon dates available for this time span is not sufficient to establish an absolute chronological sequence. Here we present a new set of short-lived radiocarbon dates from the sites of Lefkandi, Kalapodi and Corinth in Greece. We focus on the crucial transition from the Submycenaean to the Protogeometric periods. This transition is placed in the late 11(th) century BCE according to the Conventional Aegean Chronology and in the late 12(th) century BCE according to the High Aegean Chronology. Our results place it in the second half of the 11(th) century BCE.

  14. Towards an Absolute Chronology for the Aegean Iron Age: New Radiocarbon Dates from Lefkandi, Kalapodi and Corinth

    PubMed Central

    Toffolo, Michael B.; Fantalkin, Alexander; Lemos, Irene S.; Felsch, Rainer C. S.; Niemeier, Wolf-Dietrich; Sanders, Guy D. R.; Finkelstein, Israel; Boaretto, Elisabetta

    2013-01-01

    The relative chronology of the Aegean Iron Age is robust. It is based on minute stylistic changes in the Submycenaean, Protogeometric and Geometric styles and their sub-phases. Yet, the absolute chronology of the time-span between the final stages of Late Helladic IIIC in the late second millennium BCE and the archaic colonization of Italy and Sicily toward the end of the 8th century BCE lacks archaeological contexts that can be directly related to events carrying absolute dates mentioned in Egyptian/Near Eastern historical sources, or to well-dated Egyptian/Near Eastern rulers. The small number of radiocarbon dates available for this time span is not sufficient to establish an absolute chronological sequence. Here we present a new set of short-lived radiocarbon dates from the sites of Lefkandi, Kalapodi and Corinth in Greece. We focus on the crucial transition from the Submycenaean to the Protogeometric periods. This transition is placed in the late 11th century BCE according to the Conventional Aegean Chronology and in the late 12th century BCE according to the High Aegean Chronology. Our results place it in the second half of the 11th century BCE. PMID:24386150

  15. Measurement of extensional viscosity by the stretching of viscoelastic liquid columns. Quarterly report, April--June, 1995

    SciTech Connect

    Calvo, D.; Chigier, N.

    1995-10-01

    Recent work in the field of atomization has explored the breakup of viscoelastic liquids. Studies have observed that viscoelastic liquids are much more resistant to breakup in comparison with Newtonian liquids. This high resistance to breakup has been attributed to the high extensional viscosities that viscoelastic liquids possess. Although extensional viscosity has been identified as having a major influence on the mode of breakup, no studies have yet been successful in correlating spray quality with a parameter that is truly description of the extensional viscosity of viscoelastic liquids. In this study, a new method is used to determine the extensional viscosities of viscoelastic liquids by the stretching of liquid columns. This method is used to show quantitative variations in extensional viscosity as a function of polymer concentration in aqueous solutions of polyacrylamide e10. Results suggest that as polymer concentration is increased, the liquids exhibit extension thickening behavior.

  16. Shear and extensional rheology of hydroxypropyl cellulose melt using capillary rheometry.

    PubMed

    Paradkar, Anant; Kelly, Adrian; Coates, Phil; York, Peter

    2009-02-20

    With increasing interest in hot melt extrusion for preparing polymer-drug systems, knowledge of the shear and extensional rheology of polymers is required for the formulation and process design. Shear and extensional rheology of three commercial grades of hydroxypropyl cellulose (HPC) was examined at 140, 145 and 150 degrees C using twin bore capillary rheometry at range of processing rates. The power law model fitted for shear flow behaviour up to shear strain rates of approximately 1000s(-1), above which measured shear viscosities deviated from the power law and surface instabilities were observed in the extrudate, particularly for higher molecular weight grades. Shear thinning index was found to be relatively independent of temperature and molecular weight, whilst the consistency index, indicative of zero shear viscosity increased exponentially with increase in molecular weight. Extensional viscosity of all grades studied was found to decrease with increasing temperature and increasing processing rate. Foaming of the extrudate occurred especially at low temperatures and with the high molecular weight grade. An understanding of the relationships between shear and extensional flows with temperature, processing rate and molecular weight is a useful tool for process design; optimisation and troubleshooting of Hot melt extrusion (HME) of pharmaceutical formulations.

  17. Enhanced Dissolution of Liquid Microdroplets in the Extensional Creeping Flow of a Hydrodynamic Trap.

    PubMed

    Mustafa, Adil; Erten, Ahmet; Ayaz, Rana M Armaghan; Kayıllıoğlu, Oğuz; Eser, Aysenur; Eryürek, Mustafa; Irfan, Muhammad; Muradoglu, Metin; Tanyeri, Melikhan; Kiraz, Alper

    2016-09-20

    A novel noncontact technique based on hydrodynamic trapping is presented to study the dissolution of freely suspended liquid microdroplets into a second immiscible phase in a simple extensional creeping flow. Benzyl benzoate (BB) and n-decanol microdroplets are individually trapped at the stagnation point of a planar extensional flow, and dissolution of single microdroplets into an aqueous solution containing surfactant is characterized at different flow rates. The experimental dissolution curves are compared to two models: (i) the Epstein-Plesset (EP) model which considers only diffusive mass transfer, and (ii) the Zhang-Yang-Mao (ZYM) model which considers both diffusive and convective mass transfer in the presence of extensional creeping flow. The EP model significantly underpredicts the experimentally determined dissolution rates for all experiments. In contrast, very good agreement is observed between the experimental dissolution curves and the ZYM model when the saturation concentration of the microdroplet liquid (cs) is used as the only fitting parameter. Experiments with BB microdroplets at low surfactant concentration (10 μM) reveal cs values very similar to that reported in the literature. In contrast, experiments with BB and n-decanol microdroplets at 10 mM surfactant concentration, higher than the critical micelle concentration (CMC) of 5 mM, show further enhancements in microdroplet dissolution rates due to micellar solubilization. The presented method accurately tests the dissolution of single microdroplets into a second immiscible phase in extensional creeping flow and has potential for applications such as separation processes, food dispersion, and drug development/design.

  18. Early Cretaceous extensional reworking of the Triassic HP-UHP metamorphic orogen in Eastern China

    NASA Astrophysics Data System (ADS)

    Lin, W.; Ji, W.; Faure, M.; Wu, L.; Li, Q. L.; Shi, Y.; Scharer, U.; Wang, F.; Wang, Q.

    2015-12-01

    Corresponding to the Early Mesozoic continental subduction between the North China Block (NCB) and the South China Block (SCB), the Tongbaishan-Hong'an-Dabieshan-Sulu massifs are famous for their HP-UHP metamorphism. More than 50% of the HP-UHP Orogenic Belt was significantly reworked by Early Cretaceous extensional tectonics. This Early Cretaceous event with a fast cooling period, at 130-120 Ma, superimposed on the Early Mesozoic HP-UHP orogenic belt and intensively changed the architecture of this orogen. Each individual segment documents different Early Cretaceous extensional structures, namely the central Tongbaishan domain is a metamorphic core complex (MCC) represented by an A-type non-cylindrical antiform; the central Dabieshan domain is a typical Cordilleran-type migmatite-cored MCC; the Southern Sulu UHP domain is a "wedge-shaped" structure exhumed by a simple detachment fault. These late stage extensional structures expose the previous HP-UHP orogenic belt as fragments along the NCB-SCB boundary. The geodynamic setting of this Early Cretaceous extensional tectonics along the HP-UHP orogen is a part of a 1000 km-scale crustal extension belt that is widespread in eastern Eurasia continent from Trans-Baikal to the central part of the South China Block. Convective erosion or delamination of the mantle lithosphere might be considered as a possible mechanism for mantle removal.

  19. Early Cretaceous extensional reworking of the Triassic HP-UHP metamorphic orogen in Eastern China

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Ji, Wenbin; Faure, Michel; Wu, Lin; Li, Qiuli; Shi, Yonghong; Scharer, Urs; Wang, Fei; Wang, Qingchen

    2015-11-01

    Corresponding to the Early Mesozoic continental subduction between the North China Block (NCB) and the South China Block (SCB), the Tongbaishan-Hong'an-Dabieshan-Sulu massifs are famous for their HP-UHP metamorphism. More than 50% of the HP-UHP Orogenic Belt was significantly reworked by Early Cretaceous extensional tectonics. This Early Cretaceous event with a fast cooling period, at 130-120 Ma, superimposed on the Early Mesozoic HP-UHP orogenic belt and intensively changed the architecture of this orogen. Each individual segment documents different Early Cretaceous extensional structures, namely the central Tongbaishan domain is a metamorphic core complex (MCC) represented by an A-type non-cylindrical antiform; the central Dabieshan domain is a typical Cordilleran-type migmatite-cored MCC; the Southern Sulu UHP domain is a "wedge-shaped" structure exhumed by a simple detachment fault. These late stage extensional structures expose the previous HP-UHP orogenic belt as fragments along the NCB-SCB boundary. The geodynamic setting of this Early Cretaceous extensional tectonics along the HP-UHP orogen is a part of a 1000 km-scale crustal extension belt that is widespread in eastern Eurasia continent from Trans-Baikal to the central part of SCB. Convective erosion or delamination of the mantle lithosphere might be considered as a possible mechanism for mantle removal.

  20. Volcanic history of the Colorado River extensional corridor: Active or passive rifting

    SciTech Connect

    Howard, K.A. )

    1993-04-01

    Magmatism and extension began nearly simultaneously in the Colorado River extensional corridor (CREC) between 34 and 35[degree] N. Initial eruptions of basanite at 23--19.5 Ma were low-volume but spanned a region now twice as wide as the 100-km-wide corridor. Extensional tilting of this age was local. A large flux of calc-alkaline basalt, andesite, dacite, and rhyolite was erupted at 22--18.5 Ma. They accumulated to average thicknesses of [approximately]1 km in the early CREC basin, and were accompanied by extensional tilting. Dike swarms, necks, and plutons represent intrusive equivalents. Plutons concentrate in the central belt of metamorphic core complexes, the most highly extended areas. Massive eruption at 18.5 Ma of the rhyolitic Peach Springs Tuff marked an ensuing lowered rate of volcanic output, a change to bimodal volcanism, much tilting and extension, and deposition of thick (to [approximately]2 km) synextensional clastic sediments 18--14 Ms. By 14--12 Ma, extensional tilting had largely ceased, and eruptions were sparse and basaltic only, as they have been since. Basalt compositions reveal changing patterns of trace-element composition that bear on sources. The early basanites have OIB-like compositions on spidergram plots, suggesting origin from the asthenosphere as would be expected from initiation of rifting driven by hot mantle upwelling. Basalts 20--12 Ma show low concentrations of Nb and Ta as in subduction-related arc magmas. Post-extensional basalts erupted 15--10 Ma exhibit a transition back toward primitive compositions seen in Quaternary alkalic basalts.

  1. Temporal and spatial variations in provenance of Eastern Mediterranean Sea sediments: Implications for Aegean and Aeolian arc volcanism

    NASA Astrophysics Data System (ADS)

    Klaver, Martijn; Djuly, Thomas; de Graaf, Stefan; Sakes, Alex; Wijbrans, Jan; Davies, Gareth; Vroon, Pieter

    2015-03-01

    The Eastern Mediterranean Sea (EMS) is the last remnant of the Tethys Ocean that has been subducted to the north since the Jurassic. Subduction has led to the formation of multiple island arcs in the EMS region where the Aeolian and Aegean arcs are currently active. The EMS is surrounded by continents and receives a large sediment input, part of which is transported down with the subducting slab into the mantle and potentially contributes a major flux to the arc volcanism. An along-arc gradient in the composition of subducting sediment has been evoked to explain the distinct geochemical signature of the easternmost volcanic centre of the Aegean arc, but direct evidence for this proposal is lacking. We present a detailed study of the mineralogical, major-, trace elements and Sr-Nd-Hf-Pb isotope composition of 45 Neogene EMS sediment samples obtained from Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) drill sites and box cores to characterise their geochemical composition, distinguish provenance components and investigate the temporal and spatial variation in provenance to evaluate the potential changing contribution of subducted EMS sediment to Aegean and Aeolian arc volcanism. Based on trace element characteristics of EMS sediments, we can distinguish four provenance components. Nile sediment and Sahara dust are the main components, but contributions from the Tethyan ophiolite belt and arc volcanic rocks in the north are also recognised. Pliocene and Quaternary EMS sediment records a strong geochemical gradient where Nile River sediment entering the EMS in the east is progressively diluted by Sahara Desert dust towards the west. Pre-Messinian samples, however, have a remarkably homogeneous composition with Nile sediment characteristics. We relate this rapid increase in Sahara dust contribution to a late Miocene climate shift leading to decreased Nile runoff and aridification of the Sahara region. EMS sediment has a restricted range in Pb isotopes

  2. Viability and Management Targets of Mediterranean Demersal Fisheries: The Case of the Aegean Sea

    PubMed Central

    Tserpes, George; Maravelias, Christos; Carvalho, Natacha; Merino, Gorka

    2016-01-01

    Management of the Mediterranean demersal stocks has proven challenging mainly due to the multi-species character of the fisheries. In the present work, we focus on the multi-species demersal fisheries of the Aegean Sea (eastern Mediterranean) aiming to study the effects of different management measures on the main commercial stocks, as well as to explore the economic viability of the fisheries depending upon these resources, by means of simulated projections. Utilizing the limited available data, our results demonstrated that, under the current exploitation pattern, the economic viability of the fleets is threatened, particularly if fuel prices increase. Additionally, the biological targets set for the most exploited species, such as hake, will not be met under the current management regime. The projections also showed that the only management scenario under which both resource sustainability and economic viability of the fisheries are ensured is the decrease of fleet capacity in terms of vessel numbers. In this case, however, measures to support the fisheries-dependent communities need to be implemented to prevent the collapse of local economies due to employment decrease. Scenarios assuming selectivity improvements would be also beneficial for the stocks but they showed low economic performance and their application would threaten the viability of the fleets, particularly that of the trawlers. PMID:28033348

  3. The Sponge Community of a Subtidal Area with Hydrothermal Vents: Milos Island, Aegean Sea

    NASA Astrophysics Data System (ADS)

    Pansini, M.; Morri, C.; Bianchi, C. N.

    2000-11-01

    Sponges were sampled by SCUBA diving at six subtidal rocky sites, three of which were close to hydrothermal vents, a common feature on the sea-floor off the south-east coast of Milos. Twenty-five species (2 Calcarea and 23 Demospongiae) were found, few compared with the 589 recorded for the Mediterranean, but an important addition to the scant information on the sponge fauna of the Aegean Sea. The number of species found at vent sites was consistently higher than that found at non-vent sites, but no vent-obligate species could be identified. However, Geodia cydonium and three species of Cliona ( C. copiosa, C. nigricans and C. rhodensis) showed a tendency to colonize vent areas. The former might take advantage of increased silica availability, the latter of the enhanced deposition of carbonates near vents. Substratum cover by sponges (estimated from wire-framed photographs of 0·7 m 2), varied greatly both among and within sites, mostly according to slope. Most sponge species preferred vertical to overhanging, shaded substrata. Proximity to vents seemed to have little or no influence on sponge cover, notwithstanding a primary effect on species diversity.

  4. Polychaetes associated with the sciaphilic alga community in the northern Aegean Sea: spatial and temporal variability

    NASA Astrophysics Data System (ADS)

    Antoniadou, C.; Nicolaidou, A.; Chintiroglou, C.

    2004-10-01

    Polychaete biodiversity has received little attention despite its importance in biomonitoring. This study describes polychaete diversity, and its spatial and temporal variability in infralittoral, hard substrate assemblages. Seven stations were chosen in the central area of the northern Aegean Sea. At each station, one to three depth levels were set (15, 30 and 40 m). Five replicates were collected by scuba diving with a quadrat sampler (400 cm2) from each station and depth level during summer for the spatial analysis, and seasonally for the study of temporal changes. Common biocoenotic methods were employed (estimation of numerical abundance, mean dominance, frequency, Margalef's richness, Shannon-Weaver index and Pielou's evenness). A total of 5,494 individuals, belonging to 79 species, were counted and classified. Diversity indices were always high. Clustering and multidimensional scaling techniques indicated a high heterogeneity of the stations, although these were all characterized by the sciaphilic alga community. A clear seasonal pattern was not detectable. Summer and autumn samples discriminate, while winter and spring form an even group. The abundance/biomass comparison indicated a dominance of k-strategy patterns, characteristic of stable communities.

  5. Mesozooplankton stable isotope composition in Cyprus coastal waters and comparison with the Aegean Sea (eastern Mediterranean)

    NASA Astrophysics Data System (ADS)

    Hannides, Cecelia C. S.; Zervoudaki, Soultana; Frangoulis, Constantin; Lange, Manfred A.

    2015-03-01

    Here we use bulk and amino acid-specific stable nitrogen (N) isotope analysis (AA-CSIA) to evaluate seasonal and regional change in mesozooplankton dynamics for the first time in coastal waters of the eastern Mediterranean. Cyprus mesozooplankton δ15N values were significantly higher in late winter (2.3‰) than in summer (1.2‰), and in all cases were less than the δ15N values of mesozooplankton in the northeast Aegean Sea (NEA; 3.4‰). AA-CSIA indicates that these differences can primarily be attributed to seasonal and regional change in mesozooplankton community trophic structure, with overall trophic position increasing by 0.2-0.3 in winter as compared to summer around Cyprus, and trophic position higher in the NEA than in Cyprus by 0.3-0.6. Such differences are most likely related to the larger contribution of carnivorous mesozooplankton observed in winter around Cyprus and in the NEA. Overall, our findings indicate change in bulk mesozooplankton δ15N value in the eastern Mediterranean is primarily driven by change in community trophic position, rather than variability in δ15N value at the base of the food web.

  6. Long-Term Marine Traffic Monitoring for Environmental Safety in the Aegean Sea

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, T.; Gyftakis, S.; Charou, E.; Perantonis, S.; Nivolianitou, Z.; Koromila, I.; Makrygiorgos, A.

    2015-04-01

    The Aegean Sea is characterized by an extremely high marine safety risk, mainly due to the significant increase of the traffic of tankers from and to the Black Sea that pass through narrow straits formed by the 1600 Greek islands. Reducing the risk of a ship accident is therefore vital to all socio-economic and environmental sectors. This paper presents an online long-term marine traffic monitoring work-flow that focuses on extracting aggregated vessel risks using spatiotemporal analysis of multilayer information: vessel trajectories, vessel data, meteorological data, bathymetric / hydrographic data as well as information regarding environmentally important areas (e.g. protected high-risk areas, etc.). A web interface that enables user-friendly spatiotemporal queries is implemented at the frontend, while a series of data mining functionalities extracts aggregated statistics regarding: (a) marine risks and accident probabilities for particular areas (b) trajectories clustering information (c) general marine statistics (cargo types, etc.) and (d) correlation between spatial environmental importance and marine traffic risk. Towards this end, a set of data clustering and probabilistic graphical modelling techniques has been adopted.

  7. Temporal and spatial biomonitoring of heavy metals in eastern Aegean coastal waters using Amphibalanus amphitrite.

    PubMed

    Onen, S Aydin; Kucuksezgin, F; Kocak, F

    2011-11-01

    This biomonitoring study presents the spatial and temporal distributions of heavy metals in the soft tissues of a major fouling species Amphibalanus amphitrite living on hard substrate at different sites along the eastern Aegean coast. A. amphitrite has been chosen as a strong candidate for monitoring heavy metals. Sediment and seawater samples were also collected to detect their metal contents in order to gain more information on the environmental conditions and possible bioaccumulation patterns. The physico-chemical characteristics of sampling stations have been measured in order to characterize the sampling area. The order of metal concentrations in barnacles, sediment and seawater decreased in the following order Cu>Fe>Zn>Mn>Cd>Cr>Pb>Hg, Fe>Mn>Zn>Cu>Pb>Cr>Hg>Cd and Fe>Zn>Mn>Cu>Pb>Cr>Cd>Hg, respectively. These results showed that barnacles accumulate Cu in a higher degree than both sediment and seawater. Moreover, metal concentrations in barnacle have the potential for use in any future regulatory framework monitoring and eventually controlling ambient metal pollution levels.

  8. Offshore wind speed and wind power characteristics for ten locations in Aegean and Ionian Seas

    NASA Astrophysics Data System (ADS)

    Bagiorgas, Haralambos S.; Mihalakakou, Giouli; Rehman, Shafiqur; Al-Hadhrami, Luai M.

    2012-08-01

    This paper utilizes wind speed data measured at 3 and 10 m above water surface level using buoys at 10 stations in Ionian and Aegean Seas to understand the behaviour of wind and thereafter energy yield at these stations using 5 MW rated power offshore wind turbine. With wind power densities of 971 and 693 W/m2 at 50 m above water surface level, Mykonos and Lesvos were found to be superb and outstanding windy sites with wind class of 7 and 6, respectively. Other locations like Athos, Santorini and Skyros with wind power density of more than 530 W/m2 and wind class of 5 were found to be the excellent sites. Around 15-16% higher winds were observed at 10 m compared to that at 3 m. Lower values of wind speed were found during summer months and higher during winter time in most of the cases reported in the present work. Slightly decreasing (~2% per year) linear trends were observed in annual mean wind speed at Lesvos and Santorini. These trends need to be verified with more data from buoys or from nearby onshore meteorological stations. At Athos and Mykonos, increasing linear trends were estimated. At all the stations the chosen wind turbine could produce energy for more than 70% of the time. The wind speed distribution was found to be well represented by Weibull parameters obtained using Maximum likelihood method compared to WAsP and Method of Moments.

  9. Sea cliff erosion in the eastern part of the North Aegean coastline, Northern Greece.

    PubMed

    Xeidakis, George S; Delimani, P K; Skias, S G

    2006-01-01

    The coastal zone is an area where many human activities are taking place. Erosion of the coast obstructs, in various ways, these activities creating occasionally serious socioeconomic and environmental problems. In this paper the coastal erosion problems encountered in the eastern Greek part of the North Aegean Sea Coast, a stretch of about 51 km long adjacent to the city of Alexandroupolis, are discussed. Given the observed type and location of erosion and other sea-action phenomena, the coast under study is divided in two parts/stretches. The western stretch, where the city of Alexandroupolis is presently extending, presents, mainly, cliff erosion problems and retreat of the coastline, very serious in some sections; whereas, the eastern stretch (to the east of the city) exhibits deposition and progression seawards due to the abundance of sediments supplied by Evros river delta. A classification of the coastline according to its relief, geologic material, erosion characteristics and rate, slope failure phenomena as well as the wave energy potential, is presented together with suggestions for case-appropriate mitigation and protection measures regarding the coastal erosion problems. The paper is focusing on the cliff erosion phenomena, since varying in height coastal cliffs made of soft rocks, cover the major part of the investigated coastline (western stretch).

  10. Bacterial pollution, activity and heterotrophic diversity of the northern part of the Aegean Sea, Turkey.

    PubMed

    Çiftçi Türetken, Pelin S; Altuğ, Gülşen

    2016-02-01

    Isolation and characterization studies of marine heterotrophic bacteria are important to describe and understand eco-metobolism of the marine environments. In this study, diversity and community structures of the culturable heterotrophic bacteria, metabollicaly active bacteria and bacterial pollution in the coastal and offshore areas of Gökçeada Island, in the Northern Aegean Sea, Turkey were investigated from March 2012 to November 2013. The primary hydrographic parameters were recorded in situ. The frequency of the metabolically active bacteria was determined by using a modified staining technique. The indicator bacteria were determined by using membrane filtration technique; 126 bacteria isolates, 24 of them first records for this region, were identified using an automated micro-identification system, VITEK2 Compact30. The results showed that detected bacterial community profiles were significantly different when compared with previous studies conducted in polluted marine areas of Turkey. High frequency of faecal bacteria detected at station 2 indicated that increasing human activities and terrestrial pollution sources are shaping factors for possible risks, regarding recreational uses of this region, in the summer seasons.

  11. Macrobenthic community structure over the continental margin of Crete (South Aegean Sea, NE Mediterranean)

    NASA Astrophysics Data System (ADS)

    Tselepides, Anastasios; Papadopoulou, Konstantia-N.; Podaras, Dimitris; Plaiti, Wanda; Koutsoubas, Drosos

    2000-08-01

    Macrobenthic faunal composition, abundance, biomass and diversity together with a suite of sedimentary environmental parameters were investigated on a seasonal basis in order to determine factors regulating faunal distribution over the oligotrophic continental margin of the island of Crete (South Aegean Sea, North Eastern Mediterranean). Macrofaunal species composition was similar to that of the western Mediterranean and the neighboring Atlantic having several common dominant species. Mean benthic biomass, abundance and diversity decreased with depth, with a major transition zone occurring at 540 m, beyond which values declined sharply. At comparable depths biomass and abundance values were considerably lower to those found in the Atlantic, high-lighting the extreme oligotrophy of the area. The continental margin of Crete was characterised by a high diversity upper continental shelf environment (dominated by surface deposit feeding polychaetes) and a very low diversity slope and deep-basin environment (dominated by carnivorous and filter feeding polychaetes). Classification and ordination analyses revealed the existence of four principle clusters divided by a faunal boundary between 200 and 540 m, as well as beyond 940 m depth. Significant correlations between macrofauna and sediment parameters led to the conclusion that besides depth, food availability (as manifested by the concentration of chloroplastic pigments) is the principle regulating factor in the system. Such being the case, the prevailing hydrographic features that structure the pelagic food web and are directly responsible for the propagation of organic matter to the benthos also affect its community structure.

  12. Extensional tectonics, halokinesis, eustacy in the Norwegian Central Graben, North Sea: A testing ground for sequence and seismic stratigraphic principles

    SciTech Connect

    Spencer, P.A. ); Prosser, S.D. )

    1996-01-01

    The Norwegian Central Graben is a mature hydrocarbon province with proven reserves within the Upper Jurassic succession. Several phases of extensional tectonics ranging from the Permo-Triassic to the Upper Jurassic, and a thick mobile salt section, serve to complicate a clear regional understanding of the area. A full integration of structural interpretation, seismic and sequence stratigraphic principles, biostratigraphy and core studies is required to achieve a realistic interpretation and predict Upper Jurassic facies distributions within this complex area. Utilizing some 30 wells, regional seismic data and biostratigraphy, candidate sequence boundaries and regionally correlatable flooding surfaces (e.g. Eudoxus), have been identified. Horizon flattening on these surfaces has allowed the recognition of thickening-away reflection geometries adjacent to salt features and divergent geometries into graben boundary faults. This facilitates the identification of the dominant local or regional controls on accommodation space creation. Detailed seismic facies analysis was then used to reveal the relative expansion or suppression of depositional systems tracts as a response to either regional or local structural controls. It was subsequently possible to place these systems within a biostratigraphically constrained regional framework. Mapping the base Zechstein, base Jurassic and base Cretaceous horizons has provided a map view of the active faults and slopes controlling sediment transport at any given time. This provided the third dimension essential in depicting the spatial distribution of depositional systems, and is a crucial component of any sequence stratigraphic interpretation. A regional picture of the progressive evolution of this complex area has been thus been derived, and the effect of both regional and local controls on sequence stratigraphic expressions has been determined.

  13. Extensional tectonics, halokinesis, eustacy in the Norwegian Central Graben, North Sea: A testing ground for sequence and seismic stratigraphic principles

    SciTech Connect

    Spencer, P.A.; Prosser, S.D.

    1996-12-31

    The Norwegian Central Graben is a mature hydrocarbon province with proven reserves within the Upper Jurassic succession. Several phases of extensional tectonics ranging from the Permo-Triassic to the Upper Jurassic, and a thick mobile salt section, serve to complicate a clear regional understanding of the area. A full integration of structural interpretation, seismic and sequence stratigraphic principles, biostratigraphy and core studies is required to achieve a realistic interpretation and predict Upper Jurassic facies distributions within this complex area. Utilizing some 30 wells, regional seismic data and biostratigraphy, candidate sequence boundaries and regionally correlatable flooding surfaces (e.g. Eudoxus), have been identified. Horizon flattening on these surfaces has allowed the recognition of thickening-away reflection geometries adjacent to salt features and divergent geometries into graben boundary faults. This facilitates the identification of the dominant local or regional controls on accommodation space creation. Detailed seismic facies analysis was then used to reveal the relative expansion or suppression of depositional systems tracts as a response to either regional or local structural controls. It was subsequently possible to place these systems within a biostratigraphically constrained regional framework. Mapping the base Zechstein, base Jurassic and base Cretaceous horizons has provided a map view of the active faults and slopes controlling sediment transport at any given time. This provided the third dimension essential in depicting the spatial distribution of depositional systems, and is a crucial component of any sequence stratigraphic interpretation. A regional picture of the progressive evolution of this complex area has been thus been derived, and the effect of both regional and local controls on sequence stratigraphic expressions has been determined.

  14. A double-cycle lake basin formed in extensional to transtensional setting: The Paleogene Nanpu Sag, Bohai Bay Basin, China

    NASA Astrophysics Data System (ADS)

    Zhang, Jianguo; Jiang, Zaixing; Gierlowski-Kordesch, Elizabeth; Xian, Benzhong; Li, Zhenpeng; Wang, Siqi; Wang, Xiabin

    2017-03-01

    It has been known that both extensional and transtensional tectonics commonly trigger a one-cycle evolution of lake sediments, but lake-cycle development co-controlled by extensional and transtensional tectonics still need identification. Here we report a double-cycle of lake sediments formed in extensional to transtensional phases in the Paleogene Nanpu Sag of the Bohai Bay Basin, China. The sag successively experienced five phases of lake-type evolution, characterized by: 1) overfilled, 2) balanced-fill, 3) overfilled, 4) balanced-fill, and 5) overfilled. Extensional tectonics was responsible for the opening of the basin and the initial creation of accommodation (1st through 3rd phase). Next, subsidence increased again through transtensional tectonics resulting in the creation of new accommodation (4th-5th phases). Investigations show this double-cycle lake-type evolution is also present in other lake-basins with similar tectonic settings (e.g., both extensional and transtensional tectonics). A different exploration and exploitation strategy should be devoted to the double-cycle evolution of lake basins controlled by extensional to transtensional tectonics in comparison to the single-cycle evolution in extensional or transtensional lake basins.

  15. Reconstructing Holocene sea surface salinity changes in the Northern Aegean Sea: evidence from morphological variations of Emiliania huxleyi-coccoliths

    NASA Astrophysics Data System (ADS)

    Herrle, Jens O.; Gebühr, Christina; Bollmann, Jörg; Giesenberg, Annika; Kranzdorf, Philip

    2013-04-01

    The Aegean Sea is a key area for our understanding of the impact of changes in the hydrological cycle on ocean circulation in the Mediterranean Sea. The Aegean Sea appears to be very sensitive to climate changes in Europe because of its small volume and the position between high- and low-latitude climate regimes. Therefore, it is assumed to record environmental change, especially changes in sea surface water salinity (SSS) without a significant time lag with respect to the forcing process (Rohling et al., 2002). However, up to date, SSS cannot be easily reconstructed from geological archives because several assumptions need to be made that lead to a significant error of the salinity estimates (e.g. Rohling, 2000). Here, we present the first high resolution SSS reconstruction from a Holocene sediment core based on a recently developed transfer function using the morphological variation of Emiliania huxleyi coccoliths (Bollmann & Herrle 2007, Bollmann et al., 2009). The core is located in the northern Aegean Sea (eastern Mediterranean Basin) and covers the time period 3 -11ka ago. Sea surface water salinity in the Aegean Sea has varied in concert with temperature oscillations as recorded in Greenland ice cores (iGISP2 ice core δ18O record) with a periodicity of about 900 years (Schulz & Paull, 2002). Four major SSS events can be identified at about 3.9, 4.7, 6.4, 7.4, and 8.2 ka in the northern Aegean Sea that correlate with increases in GISP2 δ18O (Schulz & Paull, 2002) as well as decreasing percentages of tree pollen studied at the same core expect for 3.9 ka (Kotthoff et al., 2008). The most prominent salinity increase occurred during the short-lived 8.2 kyr cold event (e.g., Rohling & Pälike, 2005), which was most likely triggered by a melt-water related perturbation of the Atlantic Meridional Overturning and associated decrease of ocean heat transport to the North Atlantic. We suggest that the salinity fluctuations in the northern Aegean Sea are related to

  16. Cross faults in extensional settings: Stress triggering, displacement localization, and implications for the origin of blunt troughs at Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Wilkins, Scott J.; Schultz, Richard A.

    2003-06-01

    Motivated by conflicting interpretations concerning the origin of blunt terminations of troughs at Valles Marineris, Mars, we investigate the reactivation of preexisting cross faults in response to stress changes associated with slippage along a major, basin-bounding normal fault (i.e., border fault). Coulomb stress changes indicate that cross fault reactivation is possible in both the footwalls and hanging walls of border faults, although this is dependent on the distance between the border and cross faults. Cross faults accommodate dip-slip normal motion for most border fault geometries and conditions we tested, but strike-slip motions are predicted when preexisting cross faults are vertical. Furthermore, although lateral extensions of the border fault (LEBFs) may nucleate within cross fault footwalls at all stages of border fault development, they are favored to develop when border faults and cross fault tip lines are proximal. Observations from the Valles Marineris extensional province, Mars, are consistent with (1) normal displacements along cross faults, (2) numerous examples of pit-chains, interpreted to represent surface expressions of lateral extensions to the border fault (LEBF), (3) the lack of well-developed cross faults in the footwall of border faults, and (4) the inference that tapered trough ends formed in areas that lacked cross faults prior to the main phase of extension at Valles Marineris. We suggest a new sequence of deformation that accounts for the formation of blunt-trough terminations during the major phase of Valles Marineris extension: coeval and locally bidirectional extension, that results from local stress field changes associated with border fault growth in a dominantly unidirectional remote (extensional) strain field. By implication, many of the irregular closed troughs such as Hebes Chasma are better interpreted as grabens rather than collapse depressions.

  17. Prediction of cryogenic cavitation around hydrofoil by an extensional Schnerr-Sauer cavitation model

    NASA Astrophysics Data System (ADS)

    Sun, T. Z.; Wei, Y. J.; Wang, C.

    2015-12-01

    Developing a robust computational strategy to address the rich physics characteristic involved in the thermodynamic effects on the cryogenic cavitation remains a challenging problem. The objective of this present study is to model the numerical methodology to simulate the cryogenic cavitation by implanting the thermodynamic effects to the Schnerr-Sauer cavitation model, and coupling the energy equation considered the latent heat. For this purpose, cavitating flows are investigated over a three dimensional hydrofoil in liquid hydrogen and nitrogen. Experimental measurements of pressure and temperature are utilized to validate the extensional Schnerr-Sauer cavitation model. Specifically, the further analysis of the cavitation solution with respect to the thermodynamic term is conducted. The results show that the extensional Schnerr-Sauer cavitation model predicts better accuracy to the quasi-steady cavitation over hydrofoil in the two cryogenic fluids.

  18. Long thickness-extensional waves in thin film bulk acoustic wave filters affected by interdigital electrodes.

    PubMed

    Liu, Jing; Du, Jianke; Wang, Ji; Yang, Jiashi

    2017-03-01

    We studied free vibrations of thin-film bulk acoustic wave filters with interdigital electrodes theoretically using the scalar differential equations by Tiersten and Stevens. The filters are made from AlN or ZnO films on Si substrates with ground and driving electrodes. They operate with thickness-extensional modes. The basic vibration characteristics including resonant frequencies and mode shapes were obtained. Their dependence on various geometric parameters was examined. It was found that for properly design filters there exist trapped modes whose vibrations are strong in regions with a driving electrode and decay away from the electrode edges. These trapped modes are essentially long plate thickness-extensional modes modulated by the electrode fingers. The number of trapped modes is sensitive to the geometric parameters.

  19. The rheology of aqueous solutions of ethyl hydroxy-ethyl cellulose (EHEC) and its hydrophobically modified analogue (hmEHEC): extensional flow response in capillary break-up, jetting (ROJER) and in a cross-slot extensional rheometer.

    PubMed

    Sharma, Vivek; Haward, Simon J; Serdy, James; Keshavarz, Bavand; Soderlund, Asa; Threlfall-Holmes, Phil; McKinley, Gareth H

    2015-04-28

    Cellulose derivatives containing associating hydrophobic groups along their hydrophilic backbone are used as rheology modifiers in the formulation of water-based spray paints, medicinal sprays, cosmetics and printable inks. Jetting and spraying applications of these materials involve progressive thinning and break-up of a fluid column or sheet into drops. Strong extensional kinematics develop in the thinning fluid neck. In viscous Newtonian fluids, inertial and viscous stresses oppose the surface tension-driven instability. In aqueous solutions of polymers such as Ethyl Hydroxy-Ethyl Cellulose (EHEC), chain elongation provides additional elastic stresses that can delay the capillary-driven pinch-off, influencing the sprayability or jettability of the complex fluid. In this study, we quantify the transient response of thinning filaments of cellulose ether solutions to extensional flows in a Capillary Break-up Extensional Rheometer (CaBER) and in a forced jet undergoing break-up using Rayleigh Ohnesorge Jetting Extensional Rheometry (ROJER). We also characterize the steady state molecular deformations using measurements of the flow-induced birefringence and excess pressure drop in an extensional stagnation point flow using a Cross-Slot Extensional Rheometer (CSER). We show that under the high extension rates encountered in jetting and spraying, the semi-dilute solutions of hydrophobically modified ethyl hydroxy-ethyl cellulose (hmEHEC) exhibit extensional thinning, while the unmodified bare chains of EHEC display an increase in extensional viscosity, up to a plateau value. For both EHEC and hmEHEC dispersions, the low extensibility of the cellulose derivatives limits the Trouton ratio observed at the highest extension rates attained (close to 10(5) s(-1)) to around 10-20. The reduction in extensional viscosity with increasing extension rate for the hydrophobically modified cellulose ether is primarily caused by the disruption of a transient elastic network that is

  20. Structural modeling of carbonaceous mesophase amphotropic mixtures under uniaxial extensional flow

    NASA Astrophysics Data System (ADS)

    Golmohammadi, Mojdeh; Rey, Alejandro D.

    2010-07-01

    The extended Maier-Saupe model for binary mixtures of model carbonaceous mesophases (uniaxial discotic nematogens) under externally imposed flow, formulated in previous studies [M. Golmohammadi and A. D. Rey, Liquid Crystals 36, 75 (2009); M. Golmohammadi and A. D. Rey, Entropy 10, 183 (2008)], is used to characterize the effect of uniaxial extensional flow and concentration on phase behavior and structure of these mesogenic blends. The generic thermorheological phase diagram of the single-phase binary mixture, given in terms of temperature (T) and Deborah (De) number, shows the existence of four T-De transition lines that define regions that correspond to the following quadrupolar tensor order parameter structures: (i) oblate (⊥,∥), (ii) prolate (⊥,∥), (iii) scalene O(⊥,∥), and (iv) scalene P(⊥,∥), where the symbols (⊥,∥) indicate alignment of the tensor order ellipsoid with respect to the extension axis. It is found that with increasing T the dominant component of the mixture exhibits weak deviations from the well-known pure species response to uniaxial extensional flow (uniaxial ⊥nematic→biaxial nematic→uniaxial∥paranematic). In contrast, the slaved component shows a strong deviation from the pure species response. This deviation is dictated by the asymmetric viscoelastic coupling effects emanating from the dominant component. Changes in conformation (oblate⇄prolate) and orientation (⊥⇄∥) are effected through changes in pairs of eigenvalues of the quadrupolar tensor order parameter. The complexity of the structural sensitivity to temperature and extensional flow is a reflection of the dual lyotropic/thermotropic nature (amphotropic nature) of the mixture and their cooperation/competition. The analysis demonstrates that the simple structures (biaxial nematic and uniaxial paranematic) observed in pure discotic mesogens under uniaxial extensional flow are significantly enriched by the interaction of the lyotropic

  1. Extensional flow of hyaluronic acid solutions in an optimized microfluidic cross-slot device.

    PubMed

    Haward, S J; Jaishankar, A; Oliveira, M S N; Alves, M A; McKinley, G H

    2013-07-01

    We utilize a recently developed microfluidic device, the Optimized Shape Cross-slot Extensional Rheometer (OSCER), to study the elongational flow behavior and rheological properties of hyaluronic acid (HA) solutions representative of the synovial fluid (SF) found in the knee joint. The OSCER geometry is a stagnation point device that imposes a planar extensional flow with a homogenous extension rate over a significant length of the inlet and outlet channel axes. Due to the compressive nature of the flow generated along the inlet channels, and the planar elongational flow along the outlet channels, the flow field in the OSCER device can also be considered as representative of the flow field that arises between compressing articular cartilage layers of the knee joints during running or jumping movements. Full-field birefringence microscopy measurements demonstrate a high degree of localized macromolecular orientation along streamlines passing close to the stagnation point of the OSCER device, while micro-particle image velocimetry is used to quantify the flow kinematics. The stress-optical rule is used to assess the local extensional viscosity in the elongating fluid elements as a function of the measured deformation rate. The large limiting values of the dimensionless Trouton ratio, Tr ∼ O(50), demonstrate that these fluids are highly extensional-thickening, providing a clear mechanism for the load-dampening properties of SF. The results also indicate the potential for utilizing the OSCER in screening of physiological SF samples, which will lead to improved understanding of, and therapies for, disease progression in arthritis sufferers.

  2. Induction of mammalian cell death by simple shear and extensional flows.

    PubMed

    Tanzeglock, Timm; Soos, Miroslav; Stephanopoulos, Gregory; Morbidelli, Massimo

    2009-10-01

    In this work we investigated whether the type of shear flow, to which cells are exposed, influences the initiation of cell death. It is shown that mammalian cells, indeed, distinguish between discrete types of flow and respond differently. Two flow devices were employed to impose accurate hydrodynamic flow fields: uniform steady simple shear flow and oscillating extensional flow. To distinguish between necrotic and apoptotic cell death, fluorescence activated cell sorting and the release of DNA in the culture supernatant was used. Results show that Chinese Hamster Ovaries and Human Embryonic Kidney cells will enter the apoptotic pathway when subjected to low levels of hydrodynamic stress (around 2.0 Pa) in oscillating, extensional flow. In contrast, necrotic death prevails when the cells are exposed to hydrodynamic stresses around 1.0 Pa in simple shear flow or around 500 Pa in extensional flow. These threshold values at which cells enter the respective death pathway should be avoided when culturing cells for recombinant protein production to enhance culture longevity and productivity.

  3. Extensional collapse along the Sevier Desert reflection, northern Sevier Desert basin, western United States

    NASA Astrophysics Data System (ADS)

    Coogan, James C.; Decelles, Peter G.

    1996-10-01

    Newly released and previously published seismic reflection data from the northern Sevier Desert basin provide a complete seismic transect between the tilted western margin of the basin and the eastern breakaway zone. When tied to well and surface age data, the transect delineates a continuum of extensional fault and basin fill geometries that developed between late Oligocene and Pleistocene time across the basin. A minimum of 18 km of top-to-the-west normal displacement is estimated across the Sevier Desert from only the most conspicuous growth geometries and offsets across listric normal faults that sole downward into the Sevier Desert reflection (SDR). The SDR clearly marks a normal fault zone beneath the entire basin, where stratal truncations are imaged for 50% of the 39 km length of the reflection east of the Cricket Mountains block. Restoration of extensional displacement along this entire 39 km fault length is necessary to reconstruct the pre-Oligocene configuration and erosion level of Sevier thrust sheets across the Sevier Desert area. The SDR normal fault zone underlies the former topographic crest of the Sevier orogenic belt, where it accommodated extensional collapse after cessation of regional contractile tectonism.

  4. Considering too few alternatives: The mental model theory of extensional reasoning.

    PubMed

    Chevalley, Thierry; Schaeken, Walter

    2016-01-01

    When solving a simple probabilistic problem, people tend to build an incomplete mental representation. We observe this pattern in responses to probabilistic problems over a set of premises using the conjunction, disjunction, and conditional propositional connectives. The mental model theory of extensional reasoning explains this bias towards underestimating the number of possibilities: In reckoning with different interpretations of the premises (logical rules, mental model theoretical, and, specific to conditional premises, conjunction and biconditional interpretation) the mental model theory accounts for the majority of observations. Different interpretations of a premise result in a build-up of mental models that are often incomplete. These mental models are processed using either an extensional strategy relying on proportions amongst models, or a conflict monitoring strategy. The consequence of considering too few possibilities is an erroneous probability estimate akin to that faced by decision makers who fail to generate and consider all alternatives, a characteristic of bounded rationality. We compare our results to the results published by Johnson-Laird, Legrenzi, Girotto, Legrenzi, and Caverni [Johnson-Laird, P., Legrenzi, P., Girotto, V., Legrenzi, M., & Caverni, J. (1999). Naive probability: A mental model theory of extensional reasoning. Psychological Review, 106, 62-88. doi: 10. 1037/0033-295X.106.1.62], and we observe lower performance levels than those in the original article.

  5. Modelling the 2013 North Aegean (Greece) seismic sequence: geometrical and frictional constraints, and aftershock probabilities

    NASA Astrophysics Data System (ADS)

    Karakostas, Vassilis; Papadimitriou, Eleftheria; Gospodinov, Dragomir

    2014-04-01

    The 2013 January 8 Mw 5.8 North Aegean earthquake sequence took place on one of the ENE-WSW trending parallel dextral strike slip fault branches in this area, in the continuation of 1968 large (M = 7.5) rupture. The source mechanism of the main event indicates predominantly strike slip faulting in agreement with what is expected from regional seismotectonics. It was the largest event to have occurred in the area since the establishment of the Hellenic Unified Seismological Network (HUSN), with an adequate number of stations in close distances and full azimuthal coverage, thus providing the chance of an exhaustive analysis of its aftershock sequence. The main shock was followed by a handful of aftershocks with M ≥ 4.0 and tens with M ≥ 3.0. Relocation was performed by using the recordings from HUSN and a proper crustal model for the area, along with time corrections in each station relative to the model used. Investigation of the spatial and temporal behaviour of seismicity revealed possible triggering of adjacent fault segments. Theoretical static stress changes from the main shock give a preliminary explanation for the aftershock distribution aside from the main rupture. The off-fault seismicity is perfectly explained if μ > 0.5 and B = 0.0, evidencing high fault friction. In an attempt to forecast occurrence probabilities of the strong events (Mw ≥ 5.0), estimations were performed following the Restricted Epidemic Type Aftershock Sequence (RETAS) model. The identified best-fitting MOF model was used to execute 1-d forecasts for such aftershocks and follow the probability evolution in time during the sequence. Forecasting was also implemented on the base of a temporal model of aftershock occurrence, different from the modified Omori formula (the ETAS model), which resulted in probability gain (though small) in strong aftershock forecasting for the beginning of the sequence.

  6. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc.

    PubMed

    Klaver, Martijn; Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-08-01

    This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely-operated vehicle that were analyzed for major element, trace element and Sr-Nd-Hf-Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave-bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52-60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low (206)Pb/(204)Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field.

  7. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc

    NASA Astrophysics Data System (ADS)

    Klaver, Martijn; Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-08-01

    This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely-operated vehicle that were analyzed for major element, trace element and Sr-Nd-Hf-Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave-bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52-60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low 206Pb/204Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field.

  8. A distinct source and differentiation history for Kolumbo submarine volcano, Santorini volcanic field, Aegean arc

    PubMed Central

    Carey, Steven; Nomikou, Paraskevi; Smet, Ingrid; Godelitsas, Athanasios; Vroon, Pieter

    2016-01-01

    Abstract This study reports the first detailed geochemical characterization of Kolumbo submarine volcano in order to investigate the role of source heterogeneity in controlling geochemical variability within the Santorini volcanic field in the central Aegean arc. Kolumbo, situated 15 km to the northeast of Santorini, last erupted in 1650 AD and is thus closely associated with the Santorini volcanic system in space and time. Samples taken by remotely‐operated vehicle that were analyzed for major element, trace element and Sr‐Nd‐Hf‐Pb isotope composition include the 1650 AD and underlying K2 rhyolitic, enclave‐bearing pumices that are nearly identical in composition (73 wt.% SiO2, 4.2 wt.% K2O). Lava bodies exposed in the crater and enclaves are basalts to andesites (52–60 wt.% SiO2). Biotite and amphibole are common phenocryst phases, in contrast with the typically anhydrous mineral assemblages of Santorini. The strong geochemical signature of amphibole fractionation and the assimilation of lower crustal basement in the petrogenesis of the Kolumbo magmas indicates that Kolumbo and Santorini underwent different crustal differentiation histories and that their crustal magmatic systems are unrelated. Moreover, the Kolumbo samples are derived from a distinct, more enriched mantle source that is characterized by high Nb/Yb (>3) and low 206Pb/204Pb (<18.82) that has not been recognized in the Santorini volcanic products. The strong dissimilarity in both petrogenesis and inferred mantle sources between Kolumbo and Santorini suggests that pronounced source variations can be manifested in arc magmas that are closely associated in space and time within a single volcanic field. PMID:27917071

  9. Internal wave measurements on the Cycladic Plateau of the Aegean Sea

    NASA Astrophysics Data System (ADS)

    Alford, Matthew H.; Gregg, Michael C.; Zervakis, Vassilis; Kontoyiannis, Harialos

    2012-01-01

    The internal wave climate in the southern Aegean Sea is examined with an array of two bottom-mounted acoustic Doppler current profilers and three profiling moorings deployed on the northern continental slope of the Cretan Sea for 3 months. Frequency spectra indicate an extremely weak internal wave continuum, about 4-10 times weaker than the Garrett-Munk and Levine reference levels. Spectra are instead dominated by semidiurnal internal tides and near-inertial waves, which are examined in detail by bandpass filtering. In the semidiurnal band, a barotropic tidal flow of ≈2 cm s-1 is observed, with a pronounced spring/neap modulation in phase with the lunar fortnightly cycle. One to two days following several of these spring tide periods, a distinct internal tide featuring 10-20 m vertical displacements and 15-20 cm s-1baroclinic velocities is detectable propagating upward and to the southeast. Time-mean energy increases a factor of 2-5 within about 100 m from the bottom, implying generation and/or scattering from the bottom, whose slope is nearly critical to semidiurnal internal waves over much of the array. Several strong, downward propagating near-inertial events are also seen, each of which occurs following a period of work done by the wind on the mixed layer as estimated from a nearby surface mooring. The high-frequency internal wave continuum is more temporally constant but increases substantially toward the end of the deployment. Significant but unexplained differences in kinetic energy occur between successive spring tide periods in the case of the internal tides and between successive wind events in the case of the near-inertial signals. Substantial variability is observed in the low-frequency flows, which likely contributes to the time variability of the internal wave signals.

  10. Climate change effects on the marine characteristics of the Aegean and Ionian Seas

    NASA Astrophysics Data System (ADS)

    Makris, Christos; Galiatsatou, Panagiota; Tolika, Konstantia; Anagnostopoulou, Christina; Kombiadou, Katerina; Prinos, Panayotis; Velikou, Kondylia; Kapelonis, Zacharias; Tragou, Elina; Androulidakis, Yannis; Athanassoulis, Gerasimos; Vagenas, Christos; Tegoulias, Ioannis; Baltikas, Vassilis; Krestenitis, Yannis; Gerostathis, Theodoros; Belibassakis, Kostantinos; Rusu, Eugen

    2016-12-01

    This paper addresses the effects of estimated climate change on the sea-surface dynamics of the Aegean and Ionian Seas (AIS). The main aim is the identification of climate change impacts on the severity and frequency of extreme storm surges and waves in areas of the AIS prone to flooding. An attempt is made to define design levels for future research on coastal protection in Greece. Extreme value analysis is implemented through a nonstationary generalized extreme value distribution function, incorporating time harmonics in its parameters, by means of statistically defined criteria. A 50-year time span analysis is adopted and changes of means and extremes are determined. A Regional Climate Model (RegCM3) is implemented with dynamical downscaling, forced by ECHAM5 fields under 20C3M historical data for the twentieth century and the SRES-A1B scenario for the twenty-first century. Storm surge and wave models (GreCSSM and SWAN, respectively) are used for marine climate simulations. Comparisons of model results with reanalysis and field data of atmospheric and hydrodynamic characteristics, respectively, are in good agreement. Our findings indicate that the dynamically downscaled RegCM3 simulation adequately reproduces the present general circulation patterns over the Mediterranean and Greece. Future changes in sea level pressure and mean wind fields are estimated to be small, yet significant for marine extremes. In general, we estimate a projected intensification of severe wave and storm surge events during the first half of the twenty-first century and a subsequent storminess attenuation leading to the resettlement of milder extreme marine events with increased prediction uncertainty in the second half of the twenty-first century.

  11. Two-stage partial melting during the Variscan extensional tectonics (Montagne Noire, France)

    NASA Astrophysics Data System (ADS)

    Poujol, Marc; Pitra, Pavel; Van Den Driessche, Jean; Tartèse, Romain; Ruffet, Gilles; Paquette, Jean-Louis; Poilvet, Jean-Charles

    2017-03-01

    One of the striking features that characterise the late stages of the Variscan orogeny is the development of gneiss and migmatite domes, as well as extensional Late Carboniferous and Permian sedimentary basins. It remains a matter of debate whether the formation of domes was related to the well-documented late orogenic extension or to the contractional tectonics that preceded. Migmatization and magmatism are expected to predate extension if the domes are compression-related regional anticlines, but they must both precede and be contemporaneous with extension if they are extensional core complexes. In the Montagne Noire area (southern French Massif Central), where migmatization, magmatism and the deformation framework are well documented, the age of the extensional event was unequivocally constrained to 300-290 Ma. Therefore, dating migmatization in this area is a key point for discriminating between the two hypotheses and understanding the Late Palaeozoic evolution of this part of the Variscan belt. For this purpose, a migmatite and an associated anatectic granite from the Montagne Noire dome were dated by LA-ICP-MS (U-Th-Pb on zircon and monazite) and laser probe 40Ar-39Ar (K-Ar on muscovite). Although zircon did not record any Variscan age unequivocally related to compression (380-330 Ma), two age groups were identified from the monazite crystals. A first event, at ca. 319 Ma (U-Th-Pb on monazite), is interpreted as a first stage of migmatization and as the emplacement age of the granite, respectively. A second event at ca. 298-295 Ma, recorded by monazite (U-Th-Pb) and by the muscovite 40Ar-39Ar system in the migmatite and in the granite, could be interpreted as a fluid-induced event, probably related to a second melting event identified through the syn-extensional emplacement of the nearby Montalet leucogranite ca. 295 Ma ago. The ages of these two events post-date the Variscan compression and agree with an overall extensional context for the development of the

  12. Eocene extensional exhumation of basement and arc rocks along southwesternmost Peru, Central Andes.

    NASA Astrophysics Data System (ADS)

    Noury, Mélanie; Bernet, Matthias; Sempéré, Thierry

    2014-05-01

    The overthickened crust of the current Central Andes is commonly viewed as the result of tectonic shortening. However, in the present-day terrestrial forearc and arc of southwesternmost Peru, crustal thickness increases from 30 km along the coastline to >60 km below the active arc, whereas the upper crust exhibits little to no evidence of crustal shortening and, in constrast, many extensional features. How (and when) crustal overthickness was acquired in this region is thus little understood. Because crustal overthickening often results in extensional collapse and/or significant erosion, here we address this issue through a regional-scale study of exhumation using fission-track thermochronology. The limited fission-track data previously available in the area suggested that exhumation began during the Mesozoic. In this study, we present new apatite and zircon fission-track data obtained along the current terrestrial forearc of southwesternmost Peru. This relatively restricted area presents the interest of providing extensive outcrops of Precambrian to Ordovician basement and Early Jurassic to Late Cretaceous arc plutons. In order to compare the chronology of exhumation of these units, we performed extensive sampling for fission-track dating, as well as structural mapping. Our results indicate that the basement rocks and Jurassic plutons that crop out in the Arequipa region, where the crust is now >50 km-thick, experienced a rapid cooling through the 240-110°C temperature range between ~65 and ~35 Ma. This period of rapid exhumation coincided in time with the accumulation of terrestrial forearc deposits (the Lower Moquegua Group), that exhibit many syn-sedimentary extensional features and are bounded by conspicuous normal faults, specifically along the region where intense activity of the main arc between ~90 and ~60 Ma had led to voluminous magma emplacement. This close succession of (1) intense magmatic activity and (2) regional-scale exhumation associated with

  13. Carbonate assimilation during magma evolution at Nisyros (Greece), South Aegean Arc: Evidence from clinopyroxenite xenoliths

    NASA Astrophysics Data System (ADS)

    Spandler, Carl; Martin, Lukas H. J.; Pettke, Thomas

    2012-08-01

    To contribute to the understanding of magma evolution in arc settings we investigate the oldest volcanic unit (Kanafià Synthem) of Nisyros volcano, located in the eastern Aegean Sea (Greece). The unit consists of porphyritic pillow lavas of basaltic andesite composition with trace element signatures that are characteristic of island-arc magmas. Two lava types are distinguished on the basis of geochemistry and the presence or absence of xenoliths, with the xenolith-bearing lavas having distinctly elevated Sr, MREE/HREE and MgO/Fe2O3 compared to the xenolith-free lavas. Xenoliths include relatively rare quartzo-feldspathic fragments that represent continental-type material, and coarse clinopyroxenite xenoliths that consist largely of aluminous and calcic clinopyroxene, and accessory aluminous spinel. Anorthite-diopside reaction selvages preserved around the clinopyroxenite xenoliths demonstrate disequilibrium between the xenoliths and the host magma. The xenolith clinopyroxene is distinctly enriched in most lithophile trace elements compared to clinopyroxene phenocrysts in the host magmas. A notable exception is the Sr concentration, which is similar in both clinopyroxene types. The high Al and low Na contents of the clinopyroxenites preclude a cumulate, deep metamorphic, or mantle origin for these xenoliths. Instead, their composition and mineralogy are diagnostic of skarn rocks formed by magma-carbonate interaction in the mid/upper crust. The Kanafià lavas are interpreted to have undergone crystal fractionation, magma mixing/mingling and crustal assimilation while resident in the upper crust. We show that magma-carbonate reaction and associated skarn formation does not necessarily result in easily recognised modification of the melt composition, with the exception of increasing Sr contents. Carbonate assimilation also releases significant CO2, which will likely form a free vapour phase due to the low CO2 solubility of arc magmas. In the broader context, we stress

  14. Human red blood cell behavior under homogeneous extensional flow in a hyperbolic-shaped microchannel.

    PubMed

    Yaginuma, T; Oliveira, M S N; Lima, R; Ishikawa, T; Yamaguchi, T

    2013-01-01

    It is well known that certain pathological conditions result in a decrease of red blood cells (RBCs) deformability and subsequently can significantly alter the blood flow in microcirculation, which may block capillaries and cause ischemia in the tissues. Microfluidic systems able to obtain reliable quantitative measurements of RBC deformability hold the key to understand and diagnose RBC related diseases. In this work, a microfluidic system composed of a microchannel with a hyperbolic-shaped contraction followed by a sudden expansion is presented. We provide a detailed quantitative description of the degree of deformation of human RBCs under a controlled homogeneous extensional flow field. We measured the deformation index (DI) as well as the velocity of the RBCs travelling along the centerline of the channel for four different flow rates and analyze the impact of the particle Reynolds number. The results show that human RBC deformation tends to reach a plateau value in the region of constant extensional rate, the value of which depends on the extension rate. Additionally, we observe that the presence of a sudden expansion downstream of the hyperbolic contraction modifies the spatial distribution of cells and substantially increases the cell free layer (CFL) downstream of the expansion plane similarly to what is seen in other expansion flows. Beyond a certain value of flow rate, there is only a weak effect of inlet flow rates on the enhancement of the downstream CFL. These in vitro experiments show the potential of using microfluidic systems with hyperbolic-shaped microchannels both for the separation of the RBCs from plasma and to assess changes in RBC deformability in physiological and pathological situations for clinical purposes. However, the selection of the geometry and the identification of the most suitable region to evaluate the changes on the RBC deformability under extensional flows are crucial if microfluidics is to be used as an in vitro clinical

  15. Origin and role of fluids involved in the seismic cycle of extensional faults in carbonate rocks

    NASA Astrophysics Data System (ADS)

    Smeraglia, Luca; Berra, Fabrizio; Billi, Andrea; Boschi, Chiara; Carminati, Eugenio; Doglioni, Carlo

    2016-09-01

    We examine the potentially-seismic right-lateral transtensional-extensional Tre Monti Fault (central Apennines, Italy) with structural and geochemical methods and develop a conceptual evolutionary model of extensional faulting with fluid involvement in shallow (≤3 km depth) faults in carbonate rocks. In the analysed fault zone, multiscale fault rock structures include injection veins, fluidized ultracataclasite layers, and crackle breccias, suggesting that the fault slipped seismically. We reconstructed the relative chronology of these structures through cross-cutting relationship and cathodoluminescence analyses. We then used C- and O-isotope data from different generations of fault-related mineralizations to show a shift from connate (marine-derived) to meteoric fluid circulation during exhumation from 3 to ≤1 km depths and concurrent fluid cooling from ∼68 to <30 °C. Between ∼3 km and ∼1 km depths, impermeable barriers within the sedimentary sequence created a semi-closed hydrological system, where prevalently connate fluids circulated within the fault zone at temperatures between 60° and 75 °C. During fault zone exhumation, at depths ≤1 km and temperatures <30 °C, the hydrological circulation became open and meteoric-derived fluids progressively infiltrated and circulated within the fault zone. The role of these fluids during syn-exhumation seismic cycles of the Tre Monti Fault has been substantially passive along the whole fault zone, the fluids being passively redistributed at hydrostatic pressure following co-seismic dilatancy. Only the principal fault has been characterized, locally and transiently, by fluid overpressures. The presence of low-permeability clayey layers in the sedimentary sequence contributed to control the type of fluids infiltrating into the fault zone and possibly their transient overpressures. These results can foster the comprehension of seismic faulting at shallow depths in carbonate rocks of other fold-thrust belts

  16. Rhaetian extensional tectonics in the Slovenian Basin (Southern Alps): Preliminary results of an outcrop study

    NASA Astrophysics Data System (ADS)

    Oprčkal, P.; Gale, L.; Kolar-Jurkovšek, T.; Rožič, B.

    2012-04-01

    A Late Triassic palaeogeographic position of the Slovenian Basin on the passive continental margin of the Neotethys Ocean to the East and later the Alpine Tethys to the West, implements that its evolution intimately depended on the events in these two areas of extension. Recent research of the "Bača dolomite", the typical Norian-Rhaetian lithologic unit of the Slovenian Basin, resulted in recognition of four extensional tectonic events (Gale et al., this volume). The Lower and Middle Norian tectonic pulses can be recognized throughout the basin. A weakened tectonic activity was recognized in the Rhaetian, followed by more pronounced, but spatially restricted tectonics at the Triassic-Jurassic boundary. Extensional tectonics was attributed to the diminishing rifting in the Neotethys area and to the incipient opening of the Alpine Tethys (Gale et al., this volume). The ongoing fieldwork in the vicinity of Škofja Loka (central Slovenia) resulted in the discovery of palaeofaults in the small-sized quarry that directly evidences the Late Triassic extensional tectonics. Based on superposition, the observed section of the "Bača dolomite" is of the Rhaetian age. The discovery is particularly important because it represents the first direct documentation of the Late Triassic down-faulting in the region. The lowest strata exposed consist of highly bituminous bedded dolostones with scour structures and several meters of mud-supported dolo-breccias. Breccias were downthrown along a normal fault and the created accommodation space filled with bedded dolostone. After complete leveling of topography, another differentiation took place, during which a new normal fault originated, whereas the pre-existing fault was reactivated in an antithetic sense. Thin-bedded dolostones were deposited during slowly abiding movements. The final cessation of tectonics is marked by a uniform deposition of massive dolostone, entirely overlying the fault-dissected sediments.

  17. Probing hydrogen bond interactions in a shear thickening polysaccharide using nonlinear shear and extensional rheology.

    PubMed

    Jaishankar, Aditya; Wee, May; Matia-Merino, Lara; Goh, Kelvin K T; McKinley, Gareth H

    2015-06-05

    Mamaku gum is a polysaccharide extracted from the fronds of the black tree fern found in New Zealand. The cooked pith has traditionally been used for various medicinal purposes and as a food source by the Maori people of New Zealand. It has potential applications as a thickener in the food industry and as a palliative for patients with dysphagia. Studies on the shear rheology of Mamaku gum have revealed that the gum exhibits shear thickening at a critical shear rate due to a transition from intra- to inter-molecular chain interactions upon shear-induced chain elongation. In this paper, we demonstrate that these interactions are primarily due to hydrogen bonding. We perform extensional rheology on mixtures of Mamaku gum and urea (a known disruptor of hydrogen bonds) to quantify the nature of these interactions. Capillary Breakup Extensional Rheometry (CaBER) performed on the pure Mamaku gum solutions yield plateau values of the Trouton ratio as high as ∼10(4), showing that the viscoelasticity of the gum in uniaxial elongation is much higher than in shear. For all Mamaku concentrations tested, the extensional viscosity decreases upon increasing urea concentration. Furthermore, the relaxation time decreases exponentially with increasing urea concentration. This exponential relationship is independent of the Mamaku concentration, and is identical to the relationships between urea concentration and characteristic timescales measured in nonlinear shear rheology. We show using the sticky reptation model for polymers with multiple sticker groups along the backbone how such a relationship is consistent with a linear decrease in the free energy for hydrogen bond dissociation. We then demonstrate that a time-concentration superposition principle can be used to collapse the viscoelastic properties of the Mamaku-gum/urea mixtures.

  18. The Moho in extensional tectonic settings: insights from thermo-mechanical models

    NASA Astrophysics Data System (ADS)

    Cloetingh, Sierd; Burov, Evgenii; Liviu, Matenco

    2013-04-01

    We review consequences for the crustal and lithospheric configuration of different models for the thermo-mechanical evolution of continental lithosphere in extensional tectonic settings. The lithospheric memory is key for the interplay of lithospheric stresses and rheological structure of the extending lithosphere and for its later tectonic reactivation. Other important factors are the temporal and spatial migration of extension and the interplay of rifting and surface processes. The mode of extension and the duration of the rifting phase required to lead to continental break-up is to a large extent controlled by the interaction of the extending plate with slab dynamics. We compare predictions from numerical models with observational constraints from a number of rifted back-arc basin settings and intraplate domains at large distance from convergent plate boundaries. We discuss the record of vertical motions during and after rifting in the context of stretching models developed to quantify rifted basin formation. The finite strength of the lithosphere has an important effect on the formation of extensional basins. This applies both to the geometry of the basin shape as well as to the record of vertical motions during and after rifting. We demonstrate a strong connection between the bulk rheological properties of Europe's lithosphere and the evolution of some of Europe's main rifts and back-arc system. The thermomechanical structure of the lithosphere has a major impact on continental breakup and associated basin migration processes, with direct relationships between rift duration and extension velocities, thermal evolution, and the role of mantle plumes. Compressional reactivation has important consequences for post-rift inversion, borderland uplift, and denudation, as illustrated by polyphase deformation of extensional back-arc basins in the Black Sea and the Pannonian Basin.

  19. Human red blood cell behavior under homogeneous extensional flow in a hyperbolic-shaped microchannel

    PubMed Central

    Yaginuma, T.; Oliveira, M. S. N.; Lima, R.; Ishikawa, T.; Yamaguchi, T.

    2013-01-01

    It is well known that certain pathological conditions result in a decrease of red blood cells (RBCs) deformability and subsequently can significantly alter the blood flow in microcirculation, which may block capillaries and cause ischemia in the tissues. Microfluidic systems able to obtain reliable quantitative measurements of RBC deformability hold the key to understand and diagnose RBC related diseases. In this work, a microfluidic system composed of a microchannel with a hyperbolic-shaped contraction followed by a sudden expansion is presented. We provide a detailed quantitative description of the degree of deformation of human RBCs under a controlled homogeneous extensional flow field. We measured the deformation index (DI) as well as the velocity of the RBCs travelling along the centerline of the channel for four different flow rates and analyze the impact of the particle Reynolds number. The results show that human RBC deformation tends to reach a plateau value in the region of constant extensional rate, the value of which depends on the extension rate. Additionally, we observe that the presence of a sudden expansion downstream of the hyperbolic contraction modifies the spatial distribution of cells and substantially increases the cell free layer (CFL) downstream of the expansion plane similarly to what is seen in other expansion flows. Beyond a certain value of flow rate, there is only a weak effect of inlet flow rates on the enhancement of the downstream CFL. These in vitro experiments show the potential of using microfluidic systems with hyperbolic-shaped microchannels both for the separation of the RBCs from plasma and to assess changes in RBC deformability in physiological and pathological situations for clinical purposes. However, the selection of the geometry and the identification of the most suitable region to evaluate the changes on the RBC deformability under extensional flows are crucial if microfluidics is to be used as an in vitro clinical

  20. Role of extensional tectonics in the formation of Talladega belt--Blue Ridge successor basins

    SciTech Connect

    Tull, J.F. . Dept. of Geology)

    1993-03-01

    Polydeformed and metamorphosed sequences occurring unconformably above the Cambrian-Ordovician (C-O) miogeoclinal sequence are nested within the Talladega belt (Talladega Group-TG) and Blue Ridge (Mineral Bluff Group-MBG). These successor basin sequences are 2.5--3 km thick and have a possible age range from Ordovician to Devonian, representing the youngest stratigraphic units east of the foreland. They are dominated by turbiditic metaclastic rocks derived from erosion of Grenville basement and its overlying cover of clastic and carbonate rock. Bimodal volcanic rocks occur in the TG, and within-plate mafic extrusive rocks are found in the MBG. The TG consists of a coarsening, thickening, and shallowing upward sequence with a submarine fan-like unit (Lay Dam Formation-LDF) at the base. The LDF contains a thick proximal boulder-bearing olistostromal facies with debris fan lobes stacked vertically and shed from a proximal fault scarp to the SE or S. The vertical stacking of olistostromal deposits, absence of crystalline-cored thrust sheets of this age at the structural top of the basin, and other relationships indicate that the basin did not result from detached deformation to the SE or transcurrent faulting, but rather from extensional faulting. Relationships within the C-O carbonate sequence (Sylacauga Marble Group) unconformably below the TG indicate that the TG basin developed above shallow shelf miogeoclinal rocks inboard of the continental margin hinge line, and thus indicate that Silurian-Devonian extensional structures affected relatively thick Laurentian crust. Similarities in lithofacies and stratigraphic sequence between the TG and MBG indicate that the settling of the MBG may have also been within an extensional basin but basin boundary faults have not yet been identified within the structural block below the pre-MBG unconformity. This basin developed above Laurentian crust previously thinned during late Protozoic rifting.

  1. Early-Middle Pleistocene eastward migration of the Abruzzi Apennine (central Italy) extensional domain

    NASA Astrophysics Data System (ADS)

    Galadini, Fabrizio; Messina, Paolo

    2004-01-01

    The evolution of the Apennine arc is related to the flexural retreat of the Adriatic lithosphere plate, the NE migration of the compressive front and the contemporaneous rifting of the Tyrrhenian basin. Evidence of the NE migration of the orogen can also be inferred from the analysis of the intra-Apennine Quaternary extensional tectonics. Stratigraphic and structural data collected along NE-SW transects in the Abruzzi Apennines (central Italy), indeed, indicate that the westernmost normal faults (activated during the Pliocene) have to be considered inactive since the Early Pleistocene (Turano valley fault) or the beginning of the Middle Pleistocene (Salto valley and Liri valley faults). In contrast, the easternmost faults (Campo Imperatore and Mt. Morrone faults) were activated during the Early Pleistocene and are still active, as demonstrated by the displacement of Late Pleistocene-Holocene deposits and landforms. Within the innermost portion of the extensional domain, the Fucino and upper Aterno valley fault systems show persistent activity since the Pliocene. Besides the evidence of a progressively NE-shifted intra-Apennine extension, available data suggest that a period of co-existing activity of the presently inactive and newly activated faults (e.g. Liri valley and Mt. Morrone faults, respectively) occurred during the Early Pleistocene. This indicates that for a few hundred thousand years active faults in the central Apennines were more numerous than in the period of the present tectonic regime. This may have resulted in a reduced activity per fault (lower slip rates) or an increased intra-Apennine extension rate. Quaternary faults in the Abruzzi Apennines generally coincide with pre-existing discontinuities such as old thrust ramps or syn-orogenic normal faults. Based on a simple geometric criteria, i.e. direction, dip, length of the pre-existing discontinuities located east of the investigated area, and assuming a still active NE-migration of the

  2. Effective Shear Modulus for Flexural and Extensional Waves in an Unloaded Thick Plate.

    DTIC Science & Technology

    1980-09-29

    various texts (see e.g. Timo- shenko and Goodier [6] ). The relationships between the elements of the stress tensor o and the strain tensor e are given by...Extensional Vibrations of Plates," Trans. ASME, Ser. E, J. Appl. Mech. 23, 277-283 (1956). 6. S.P. Timoshenko and J.N. Goodier , Theory of Elasticity, 3d ed...private communication), David Taylor Naval Shin Research & Development Center, 1980. D2. R. D. Mindlin, "Influence of Rotatory inertia and Shear on

  3. Relations between extensional tectonics and magmatism within the Southern Oklahoma aulacogen

    NASA Technical Reports Server (NTRS)

    Mcconnell, D. A.; Gilbert, M. C.

    1985-01-01

    Variations in the geometry, distribution and thickness of Cambrian igneous and sedimentary units within southwest Oklahoma are related to a late Proterozoic - early Paleozoic rifting event which formed the Southern Oklahoma aulacogen. These rock units are exposed in the Wichita Mountains, southwest Olkahoma, located on the northern margin of a Proterozoic basin, identified in the subsurface by COCORP reflection data. Overprinting of the Cambrian extensional event by Pennyslvanian tectonism obsured the influence of pre-existing basement structures and contrasting basement lithologies upon the initial development of the aulacogen.

  4. Extensional and Flexural Waves in a Thin-Walled Graphite/Epoxy Tube

    NASA Technical Reports Server (NTRS)

    Prosser, William H.; Gorman, Michael R.; Dorighi, John

    1992-01-01

    Simulated acoustic emission signals were induced in a thin-walled graphite/epoxy tube by means of lead breaks (Hsu-Neilsen source). The tube is of similar material and layup to be used by NASA in fabricating the struts of Space Station Freedom. The resulting waveforms were detected by broad band ultrasonic transducers and digitized. Measurements of the velocities of the extensional and flexural modes were made for propagation directions along the tube axis (0 degrees), around the tube circumference (90 degrees) and at an angle of 45 degrees. These velocities were found to be in agreement with classical plate theory.

  5. Extensional and flexural waves in a thin-walled graphite/epoxy tube

    NASA Technical Reports Server (NTRS)

    Prosser, William H.; Dorighi, John; Gorman, Michael R.

    1992-01-01

    Simulated acoustic emission signals were induced in a thin-walled graphite/epoxy tube by means of lead breaks (Hsu-Nielsen source). The tube is of similar material and layup to be used by NASA in fabricating the struts of Space Station Freedom. The resulting waveforms were detected by broad band ultrasonic transducers and digitized. Measurements of the velocities of the extensional and flexural modes were made for propagation directions along the tube axis (0 degrees), around the tube circumference (90 degrees) and at an angle of 45 degrees. These velocities were found to be in agreement with classical plate theory.

  6. Tectono-stratigraphic evolution of an inverted extensional basin: the Cameros Basin (north of Spain)

    NASA Astrophysics Data System (ADS)

    Omodeo Salè, Silvia; Guimerà, Joan; Mas, Ramón; Arribas, José

    2014-09-01

    The Cameros Basin is a part of the Mesozoic Iberian Rift. It is an extensional basin formed during the late Jurassic and early Cretaceous, in the Mesozoic Iberian Rift context, and it was inverted in the Cenozoic as a result of the Alpine contraction. This work aims to reconstruct the tectono-stratigraphic evolution of the basin during the Mesozoic, using new and revised field, geophysical and subsurface data. The construction of a basin-wide balanced section with partial restorations herein offers new insights into the geometry of the syn-rift deposits. Field data, seismic lines and oil well data were used to identify the main structures of the basin and the basin-forming mechanisms. Mapping and cross-sectional data indicate the marked thickness variation of the depositional sequences across the basin, suggesting that the extension of the depositional area varied during the syn-rift stage and that the depocentres migrated towards the north. From field observation and seismic line interpretation, an onlap of the depositional sequences to the north, over the marine Jurassic substratum, can be deduced. In the last few decades, the structure and geometry of the basin have been strongly debated. The structure and geometry of the basin infill reconstructed herein strongly support the interpretation of the Cameros Basin as an extensional-ramp synclinal basin formed on a blind south-dipping extensional ramp. The gradual hanging-wall displacement to the south shifted the depocentres to the north over time, thus increasing the basin in size northwards, with onlap geometry on the pre-rift substratum. The basin was inverted by means of a main thrust located in a detachment located in the Upper Triassic beds (Keuper), which branched in depth with the Mesozoic extensional fault flat. The reconstruction of the tectono-stratigraphic evolution of the Cameros Basin proposed herein represents a synthesis and an integration of previous studies of the structure and geometry of the

  7. Miocene extension and extensional folding in an anticlinal segment of the Black Mountains accommodation zone, Colorado River extensional corridor, southwestern United States

    USGS Publications Warehouse

    Varga, R.J.; Faulds, J.E.; Snee, L.W.; Harlan, S.S.; Bettison-Varga, L.

    2004-01-01

    Recent studies demonstrate that rifts are characterized by linked tilt domains, each containing a consistent polarity of normal faults and stratal tilt directions, and that the transition between domains is typically through formation of accommodation zones and generally not through production of throughgoing transfer faults. The mid-Miocene Black Mountains accommodation zone of southern Nevada and western Arizona is a well-exposed example of an accommodation zone linking two regionally extensive and opposing tilt domains. In the southeastern part of this zone near Kingman, Arizona, east dipping normal faults of the Whipple tilt domain and west dipping normal faults of the Lake Mead domain coalesce across a relatively narrow region characterized by a series of linked, extensional folds. The geometry of these folds in this strike-parallel portion of the accommodation zone is dictated by the geometry of the interdigitating normal faults of opposed polarity. Synclines formed where normal faults of opposite polarity face away from each other whereas anticlines formed where the opposed normal faults face each other. Opposed normal faults with small overlaps produced short folds with axial trends at significant angles to regional strike directions, whereas large fault overlaps produce elongate folds parallel to faults. Analysis of faults shows that the folds are purely extensional and result from east/northeast stretching and fault-related tilting. The structural geometry of this portion of the accommodation zone mirrors that of the Black Mountains accommodation zone more regionally, with both transverse and strike-parallel antithetic segments. Normal faults of both tilt domains lose displacement and terminate within the accommodation zone northwest of Kingman, Arizona. However, isotopic dating of growth sequences and crosscutting relationships show that the initiation of the two fault systems in this area was not entirely synchronous and that west dipping faults of the

  8. Assessment of island beach erosion due to sea level rise: the case of the Aegean archipelago (Eastern Mediterranean)

    NASA Astrophysics Data System (ADS)

    Monioudi, Isavela N.; Velegrakis, Adonis F.; Chatzipavlis, Antonis E.; Rigos, Anastasios; Karambas, Theophanis; Vousdoukas, Michalis I.; Hasiotis, Thomas; Koukourouvli, Nikoletta; Peduzzi, Pascal; Manoutsoglou, Eva; Poulos, Serafim E.; Collins, Michael B.

    2017-03-01

    The present contribution constitutes the first comprehensive attempt to (a) record the spatial characteristics of the beaches of the Aegean archipelago (Greece), a critical resource for both the local and national economy, and (b) provide a rapid assessment of the impacts of the long-term and episodic sea level rise (SLR) under different scenarios. Spatial information and other attributes (e.g., presence of coastal protection works and backshore development) of the beaches of the 58 largest islands of the archipelago were obtained on the basis of remote-sensed images available on the web. Ranges of SLR-induced beach retreats under different morphological, sedimentological and hydrodynamic forcing, and SLR scenarios were estimated using suitable ensembles of cross-shore (1-D) morphodynamic models. These ranges, combined with empirically derived estimations of wave run-up induced flooding, were then compared with the recorded maximum beach widths to provide ranges of retreat/erosion and flooding at the archipelago scale. The spatial information shows that the Aegean pocket beaches may be particularly vulnerable to mean sea level rise (MSLR) and episodic SLRs due to (i) their narrow widths (about 59 % of the beaches have maximum widths < 20 m), (ii) their limited terrestrial sediment supply, (iii) the substantial coastal development and (iv) the limited existing coastal protection. Modeling results indeed project severe impacts under mean and episodic SLRs, which by 2100 could be devastating. For example, under MSLR of 0.5 m - representative concentration pathway (RCP) 4.5 of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate change (IPCC) - a storm-induced sea level rise of 0.6 m is projected to result in a complete erosion of between 31 and 88 % of all beaches (29-87 % of beaches are currently fronting coastal infrastructure and assets), at least temporarily. Our results suggest a very considerable risk which will require significant

  9. A high-resolution geochronological and geochemical study on Aegean carbonate deposits, SW Turkey

    NASA Astrophysics Data System (ADS)

    Ünal-İmer, Ezgi; Uysal, I. Tonguç; Işık, Veysel; Zhao, Jian-Xin; Shulmeister, James

    2014-05-01

    Vein and breccia carbonates precipitated in highly fractured/faulted carbonate bedrock were investigated using high-resolution U-series geochronology, as well as through microstructural and geochemical studies including Sr-O-C isotope and REE element analyses. The study area (Kumlubük and Amos vein systems), located south of the town of Marmaris in SW Turkey, is a part of an active large-scale extensional system. Field studies show that the calcite veins generally occur sub-vertically and strike mostly NW and EW, in agreement with the regional N-S extensional stress regime. Microscopic observations indicate that the calcite veins formed through crack-seal mechanism, typically accompanied/initiated by intensive hydraulic fracturing of wall-rock evidenced by the presence of widespread breccia deposits. Vein textures are dominated by elongated, fibrous, and blocky calcites. Successive fracturing and layering of calcite with sharp contacts are traceable along the fluid inclusion bands occurring parallel to the wall rock boundary. In particular, inclusion trails aligned perpendicular to the wall-rock and calcite crystal elongation give information about the vein dilation (crack opening) vector and growth direction. High-resolution U-series dating (11-272 ka BP) and geochemical compositions of the vein and breccia samples were used to investigate the long-term behaviour as well as the general identity of the CO2-bearing fluids within deformed crust. The seismic nature of calcite veining is further assessed by stable isotopic ratio (δ18O and δ13C) plots against vein depths (distance from the wall-rock). The average δ18OPDBvalue for Kumlubük veins is -3.79o, while Amos has an average value of -4.05o. Similarly, average carbon isotope ratio (-8.30o) of the Kumlubük veins is slightly higher than that is observed for the Amos veins (-9.66o). Isotopic compositions are interpreted to reflect cyclic (or episodic) CO2 variations. This suggests the presence of several fluid

  10. Characterizing Printability of Complex Fluids using Dripping-Onto-Substrate Extensional Rheometry

    NASA Astrophysics Data System (ADS)

    Sharma, Vivek; Dinic, Jelena; Jimenez, Leidy N.; Biagioli, Madeleine; Estrada, Alexandro

    2015-11-01

    Liquid transfer and drop formation/deposition processes involved in printing, jetting, spraying and coating involve the formation of columnar necks that undergo spontaneous surface tension-driven instability, thinning and pinch-off. The thinning and pinch-off dynamics are determined by the relative magnitude of capillary forces, and inertial, viscous stresses for simple (Newtonian and inelastic) fluids. Stream-wise velocity gradients that arise within the thinning columnar neck create an extensional flow field, which induces micro-structural changes within complex fluids, contributing extra elastic stresses that change thinning and pinch-off dynamics. Though it is well-established that the quantitative analysis of neck thinning can provide a measure of extensional rheology response and arguably printability, such measurements require bespoke instrumentation not available, or easily replicated, in most laboratories. In this contribution, we describe a method that relies on understanding, visualization and analysis of capillary-driven self-thinning dynamics in an asymmetric liquid bridge formed by dripping a finite volume of fluid from a nozzle onto a substrate.

  11. Reflection of drill-string extensional waves at the bit-rock contact.

    PubMed

    Poletto, Flavio; Malusa, Massimo

    2002-06-01

    Downward propagating extensional waves are partially reflected at the bit-rock contact. The evaluation of the reflection coefficient is important to obtain while drilling information about the acoustic properties of the formations. The scope of this work is to estimate the bit-rock reflection coefficient, assuming a flat drill bit in perfect contact with the formation. Using the low-frequency approximation, which holds when the wavelength is much larger than the lateral dimensions of the borehole, the drill-string is assumed to be a laterally free rod, and the formation an homogeneous and isotropic medium. This work shows that the reflection coefficient of the extensional waves depends, along with the elastic properties of the formation, on the ratio of the cross sections of the drill-string and borehole. The impedance of the drilled rock can be calculated from the measured reflection coefficient, which is related to the amplitude of waves produced in the string and in the formation by a working drill-bit.

  12. Parameter-free prediction of DNA dynamics in planar extensional flow of semidilute solutions

    NASA Astrophysics Data System (ADS)

    Sasmal, Chandi; Hsiao, Kai-Wen; Schroeder, Charles M.; Ravi Prakash, J.

    2017-01-01

    The dynamics of individual DNA molecules in semidilute solutions undergoing planar extensional flow is simulated using a multi-particle Brownian dynamics algorithm, which incorporates hydrodynamic and excluded volume interactions in the context of a coarse-grained bead-spring chain model for DNA. The successive fine-graining protocol [1, 2], in which simulation data acquired for bead-spring chains with increasing values of the number of beads $N_b$, is extrapolated to the number of Kuhn steps $N_\\text{K}$ in DNA (while keeping key physical parameters invariant), is used to obtain parameter-free predictions for a range of Weissenberg numbers and Hencky strain units. A systematic comparison of simulation predictions is carried out with the experimental observations of [3], who have recently used single molecule techniques to investigate the dynamics of dilute and semidilute solutions of $\\lambda$-phage DNA in planar extensional flow. In particular, they examine the response of individual chains to step-strain deformation followed by cessation of flow, thereby capturing both chain stretch and relaxation in a single experiment. The successive fine-graining technique is shown to lead to quantitatively accurate predictions of the experimental observations in the stretching and relaxation phases. Additionally, the transient chain stretch following a step strain deformation is shown to be much smaller in semidilute solutions than in dilute solutions, in agreement with experimental observations.

  13. Extensional Rheology Experiment Developed to Investigate the Rheology of Dilute Polymer Solutions in Microgravity

    NASA Technical Reports Server (NTRS)

    Logsdon, Kirk A.

    2001-01-01

    A fundamental characteristic of fluid is viscosity; that is, the fluid resists forces that cause it to flow. This characteristic, or parameter, is used by manufacturers and end-users to describe the physical properties of a specific material so that they know what to expect when a material, such as a polymer, is processed through an extruder, a film blower, or a fiber-spinning apparatus. Normally, researchers will report a shear viscosity that depends on the rate of an imposed shearing flow. Although this type of characterization is sufficient for some processes, simple shearing experiments do not provide a complete picture of what a processor may expect for all materials. Extensional stretching flows are common in many polymer-processing operations such as extrusion, blow molding, and fiber spinning. Therefore, knowledge of the complete rheological (ability to flow and be deformed) properties of the polymeric fluid being processed is required to accurately predict and account for the flow behavior. In addition, if numerical simulations are ever able to serve as a priori design tools for optimizing polymer processing operations such as those described above, an accurate knowledge of the extensional viscosity of a polymer system and its variation with temperature, concentration, molecular weight, and strain rate is critical.

  14. FROM MICROCONTINENTS TO EXTENSIONAL ALLOCHTHONS: WITNESSES OF HOW CONTINENTS BREAK APART? (Invited)

    NASA Astrophysics Data System (ADS)

    Peron-Pinvidic, G.; Manatschal, G.

    2009-12-01

    It is well known that extensional processes can lead to different crustal configurations, depending notably on lithospheric composition, thermal structure and extension rate. Thereby, rifted margins are characterized, worldwide, by distinct tectonic, geological and magmatic contexts. Direct comparisons are not straightforward. However, even if different, these margins also present a limited number of crustal features that are regularly observed and described such as micro-continents, continental ribbons, H blocks, extensional allochthons and outer highs. If some of these structures have been proposed to be issued from plume-related events and strength differences between oceanic and continental lithosphere, it is still unclear how these different types of crustal bodies are generated and consequently what they may tell us about the underlying processes and associated tectonic evolution. However, we believe each of these features, by their similarities and differences, point to distinct processes (stretching, thinning, exhumation, magmatism, spreading). The aim of this contribution is to present these different "building stones", describe their characteristics and positions within the margins, and discuss the underlying tectonic processes and stratigraphic relationships related to their formation. We propose, using the example of the North Atlantic, that the superposition of specific deformation modes may explain the various types of crustal blocks and, as a consequence, that the occurrence of these various blocks are the witnesses of particular rifting processes.

  15. The importance of flow history in mixed shear and extensional flows

    NASA Astrophysics Data System (ADS)

    Wagner, Caroline; McKinley, Gareth

    2015-11-01

    Many complex fluid flows of experimental and academic interest exhibit mixed kinematics with regions of shear and elongation. Examples include flows through planar hyperbolic contractions in microfluidic devices and through porous media or geometric arrays. Through the introduction of a ``flow-type parameter'' α which varies between 0 in pure shear and 1 in pure elongation, the local velocity fields of all such mixed flows can be concisely characterized. It is tempting to then consider the local stress field and interpret the local state of stress in a complex fluid in terms of shearing or extensional material functions. However, the material response of such fluids exhibit a fading memory of the entire deformation history. We consider a dilute solution of Hookean dumbbells and solve the Oldroyd-B model to obtain analytic expressions for the entire stress field in any arbitrary mixed flow of constant strain rate and flow-type parameter α. We then consider a more complex flow for which the shear rate is constant but the flow-type parameter α varies periodically in time (reminiscent of flow through a periodic array or through repeated contractions and expansions). We show that the flow history and kinematic sequencing (in terms of whether the flow was initialized as shearing or extensional) is extremely important in determining the ensuing stress field and rate of dissipated energy in the flow, and can only be ignored in the limit of infinitely slow flow variations.

  16. Stretch-coil transition of a semiflexible filament in extensional flow

    NASA Astrophysics Data System (ADS)

    Manikantan, Harishankar; Saintillan, David

    2015-11-01

    We present a theoretical model for the fluctuation-rounded buckling transition of a semiflexible polymer placed in extensional flow. The competition between elastic rigidity and line tension developed in the polymer backbone can trigger a buckling instability, and the effect of thermal fluctuations on this bifurcation has recently gathered significant attention. While this problem has been studied experimentally and computationally before, the exact nature of the stochastic transition is yet to receive a full quantitative treatment. Motivated by the findings of recent experiments and our own numerical simulations, we approach this analytically by expanding a slender-body equation for the polymer around the first deterministic buckled mode at the onset of the instability. This leads us to a Ginzburg-Landau model for the amplitude of the buckled shape, solving which reveals an expression for a stochastic supercritical bifurcation. This solution captures the smooth transition from a stretched state to a buckled state as the extensional flow strength is increased. It matches excellently with full numerical simulations, and corroborates the conclusions drawn from recent microfluidic experiments.

  17. Avalanches of coalescence events and local extensional flows--stabilisation or destabilisation due to surfactant.

    PubMed

    Gunes, Deniz Z; Clain, Xavier; Breton, Olivier; Mayor, Guy; Burbidge, Adam S

    2010-03-01

    From two-drop collision experiments, it is known that local extensional flow favors coalescence. Recently, Bremond et al. used microfluidic methods to evidence this point. Similarly, we used specific microfluidic geometries to impose sudden extensional flow, following drop collision under controlled conditions, and coalescence events were recorded with a high-speed camera. In this study we focus on the effect of surfactant on the coalescence, or stabilisation against it, between drops flowing apart due to either imposed external flow or capillary forces related to drop shape relaxation. Coalescence can be induced even when drops are initially separated by an intersticial lubricating film by far thicker than the critical thickness for rupturing under the action of Van der Waals forces. This is particularly relevant to avalanches of coalescence events, in flowing or even quiescent emulsions or foams. When non-ionic surfactant was used, it was observed that small concentrations apparently enhance coalescence in extension. But at higher concentrations it provides stabilisation through a specific mechanism of thread formation and rupture; the stabilisation mechanism can be complex.

  18. Quaternary extensional growth folding beneath Reno, Nevada, imaged by urban seismic profiling

    USGS Publications Warehouse

    Stephenson, William J.; Frary, Roxy N.; Louie, John; Odum, Jackson K.

    2013-01-01

    We characterize shallow subsurface faulting and basin structure along a transect through heavily urbanized Reno, Nevada, with high‐resolution seismic reflection imaging. The 6.8 km of P‐wave data image the subsurface to approximately 800 m depth and delineate two subbasins and basin uplift that are consistent with structure previously inferred from gravity modeling in this region of the northern Walker Lane. We interpret two primary faults that bound the uplift and deform Quaternary deposits. The dip of Quaternary and Tertiary strata in the western subbasin increases with greater depth to the east, suggesting recurrent fault motion across the westernmost of these faults. Deformation in the Quaternary section of the western subbasin is likely evidence of extensional growth folding at the edge of the Truckee River through Reno. This deformation is north of, and on trend with, previously mapped Quaternary fault strands of the Mt. Rose fault zone. In addition to corroborating the existence of previously inferred intrabasin structure, these data provide evidence for an active extensional Quaternary fault at a previously unknown location within the Truckee Meadows basin that furthers our understanding of both the seismotectonic framework and earthquake hazards in this urbanized region.

  19. The Moho in extensional tectonic settings: Insights from thermo-mechanical models

    NASA Astrophysics Data System (ADS)

    Cloetingh, Sierd; Burov, Evgenii; Matenco, Liviu; Beekman, Fred; Roure, François; Ziegler, Peter A.

    2013-12-01

    The lithospheric memory is key for the interplay of lithospheric stresses and rheological structure of the extending lithosphere and for its later tectonic reactivation. Other important factors are the temporal and spatial migration of extension and the interplay of rifting and surface processes. The mode of extension and the duration of the rifting phase required to lead to continental break-up are to a large extent controlled by the interaction of the extending plate with slab dynamics. The finite strength of the lithosphere has an important effect on the formation of extensional basins. This applies both to the geometry of the basin shape as well as to the record of vertical motions during and after rifting. We demonstrate a strong connection between the bulk rheological properties of Europe's lithosphere and the evolution of some of Europe's main rifts and back-arc systems. The thermo-mechanical structure of the lithosphere has a major impact on continental break-up and associated basin migration processes, with direct relationships between rift duration and extension velocities, thermal evolution, and the role of mantle plumes. Compressional reactivation has important consequences for post-rift inversion, borderland uplift, and denudation, as illustrated by poly-phase deformation of extensional back-arc basins in the Black Sea and the Pannonian Basin region.

  20. Pattern of extensional faulting in pelagic carbonates of the Unbria-Marche Apennines of central Italy

    SciTech Connect

    Alvarez, W. )

    1990-05-01

    The Umbria-Marche Apennines provide a new region in which the nature passive-margin extensional faulting can be studied in outcrop. In these dominantly pelagic carbonate rocks of Jurassic and Cretaceous age, horsts acted as shallow, nonvolcani seamounts, while tilted half grabens formed deeper basins. One well-exposed seamount-basin transition agrees in general with the model of listric normal faulting and tilted half grabens, but shows interesting and significant divergences when studied in detail. A small sedimentary wedge at the faulted margin of a horst-block seamount thickens unexpectedly toward the adjacent basin. This wedge developed because of local convex-upward curvature of the shallowest part of a fault which at depth must have concave-up, listric geometry. The local sedimentary wedge resulted from deposition on the hanging wall as it tilted, followed by differential compaction of younger limestones that lapped onto the gentle slope leading from the horst-block seamount toward the basin. The map pattern of listric normal faulting in the Umbria-Marche Apennines suggests that both principal strain axes were extensional, in contrast to the usual pattern of listric faults crossed by transfer faults.

  1. Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins

    NASA Astrophysics Data System (ADS)

    Sutra, Emilie; Manatschal, Gianreto; Mohn, Geoffroy; Unternehr, Patrick

    2013-08-01

    Many recent papers describe the structure of the Iberia and Newfoundland rifted margins; however, none of them propose kinematic restorations of the complete rift system to quantify the amount of extension necessary to exhume mantle and initiate seafloor spreading. In our study, we use two pairs of cross sections considered as conjugate lines: one across the Galicia Bank-Flemish Cap and the other across the Southern Iberia Abyssal Plain-Flemish Pass. Both transects have been imaged by reflection- and refraction-seismic methods and have been drilled during Ocean Drilling Program Legs 103, 149, 173, and 210. Drilling penetrated parts of the rift stratigraphy and the underlying basement. The cross sections can therefore be considered as the best-documented conjugate transects across present-day hyperextended, magma-poor rifted margins. The aim of this paper is threefold: (1) provide a detailed description of the crustal architecture of the two conjugate sections, (2) define the extensional structures and their ages, and (3) quantify the amount of strain and strain rate accommodated along these lines. This paper proposes a quantitative description of extension along the Iberia-Newfoundland rift system and discusses the limitations and problems in quantifying extensional deformation along hyperextended rifted margins.

  2. Deformation and breakup of micro- and nanoparticle stabilized droplets in microfluidic extensional flows.

    PubMed

    Mulligan, Molly K; Rothstein, Jonathan P

    2011-08-16

    Using a microfluidic flow-focusing device, monodisperse water droplets in oil were generated and their interface populated by either 1 μm or 500 nm amine modified silica particles suspended in the water phase. The deformation and breakup of these Pickering droplets were studied in both pure extensional flow and combined extensional and shear flow at various capillary numbers using a microfluidic hyperbolic contraction. The shear resulted from droplet confinement and increased with droplet size and position along the hyperbolic contraction. Droplet deformation was found to increase with increasing confinement and capillary number. At low confinements and low capillary numbers, the droplet deformation followed the predictions of theory. For fully confined droplets, where the interface was populated by 1 μm silica particles, the droplet deformation increased precipitously and two tails were observed to form at the rear of the droplet. These tails were similar to those seen for surfactant covered droplets. At a critical capillary number, daughter droplets were observed to stream from these tails. Due to the elasticity of the particle-laden interface, these drops did not return to a spherical shape, but were observed to buckle. Although increases in droplet deformation were observed, no tail streaming occurred for the 500 nm silica particle covered droplets over the range of capillary numbers studied.

  3. Geochemistry of natural and anthropogenic metals in the coastal sediments of the island of Lesvos, Aegean Sea.

    PubMed

    Aloupi, M; Angelidis, M O

    2001-01-01

    The geochemistry of metals in the harbor and coastal zone of the town of Mytilene (island of Lesvos, Aegean Sea, Greece) was studied after normalization of the metal data to a conservative element. In the study area, Li was proven to be better suited than Al for such normalization and it was able to describe successfully the natural metal variability of the coastal sediments. Metal contamination (Cd, Cu, Pb, Zn) was recorded in the harbor sediments, while no pollution signs were detected in the wider coastal zone or the sediments of the ancient harbor, at the northern part of the town. The geochemical normalization of metal data to Li is a method that can detect the degree of metal contamination taking into consideration the natural metal variability in the sediments of a study area.

  4. Potential Health Hazard Assessment in Terms of Some Heavy Metals Determined in Demersal Fishes Caught in Eastern Aegean Sea.

    PubMed

    Yabanli, Murat; Alparslan, Yunus

    2015-10-01

    A heavy metal risk assessment based on estimated daily intake (EDI) and target hazard quotient was made for children and adults. Five fish species captured from the eastern Aegean Sea were analyzed for Cr, Cu, Cd, Hg and Pb by inductively coupled plasma spectroscopy in muscle tissue of red mullet (Mullus barbatus), surmullet (Mullus surmuletus), sand steenbras (Lithognathus mormyrus), common two-banded seabream (Diplodus vulgaris) and common pandora (Pagellus erythinus). The ranges for mean metal concentration (mg/kg wet wt) in the five species were 0.27-0.39 Cr, 0.12-0.22 Cu, 0.09-0.10 Hg and 0.10-0.12 Pb. All means were identical for Cd at 0.03 mg/kg wet wt. The EDI values for each metal were ascertained not to exceed the tolerable daily intake amount. Fish did not contain sufficiently high levels of these metals to pose a carcinogenic risk.

  5. The seasonal cycles of stratification and circulation in the Thermaikos Gulf Region Of Freshwater Influence (ROFI), north-west Aegean

    NASA Astrophysics Data System (ADS)

    Hyder, P.; Simpson, J. H.; Christopoulos, S.; Krestenitis, Y.

    2002-11-01

    The Thermaikos Gulf is a shallow basin in the north-west Aegean. Communication with the open Aegean is restricted by the long (170 km), narrow (˜50 km) nature of the Gulf and the weak tidal flows. In consequence, the northern section of the Gulf experiences severe water quality problems arising from the untreated sewage from the city of Thessaloniki (population 1.1 million), pollutant discharges from industry around the Gulf, and nutrient input from three rivers, which flow in near the head of the Gulf. New observations over a 16-month period during 1994-95 indicate distinct winter and summer circulation regimes. In winter (December-April), strong freshwater input (˜350 m 3/s) generates a thin (5 m), low salinity, surface layer which flows southward over much of the Gulf, above relatively homogeneous high-salinity waters that flow to the north. In the low-salinity layer, close to the river deltas, short pulses of extremely low-salinity water occur daily, principally as the result of releases from the Aliakmon hydro-electric power dam. Between October and February, a cold, dense water mass is observed in the deeper water of the eastern Gulf, which appears to originate in the shallow waters of central Saloniki Bay as the result of cooling during northerly gales. During winter it appears that buoyancy forcing from high run-off, in combination with persistent southward wind stress results in wind-enhanced estuarine exchange. In summer (July-September), the surface low-salinity layer is not well defined and is confined to the western Gulf in the vicinity of the river sources. Throughout the Gulf, a thicker (10-20 m) mixed layer with low salinity, warm waters overlies a strong pycnocline. A weak barotropic gyre is observed in the Gulf at this time. Monthly estimates of the total freshwater content of the northern Gulf indicate that this layer results in an accumulation of freshwater in the Gulf over the summer, when the local river input is at a minimum. It appears

  6. Evaluations of heavy metal pollution in sediment and Mullus barbatus from the Izmir Bay (Eastern Aegean) during 1997-2009.

    PubMed

    Kucuksezgin, Filiz; Kontas, Aynur; Uluturhan, Esin

    2011-07-01

    Izmir Bay is one of the great natural bays of the Mediterranean. The surface sediment and fish samples were collected during 1997-2009. The sediment concentrations of inner bay showed significant enrichments during sampling periods. Outer and middle bays exhibited low levels of metal enrichments except the estuary of Gediz River. The concentrations were generally higher than the background levels from the Mediterranean and Aegean except Cd and Pb levels gradually decreased. Metal EF is used as an index to evaluate anthropogenic influences of metals in sediments. Maximum metal enrichment was found for Hg in the outer bay, while Pb indicated maximum enrichment in the middle-inner bays. Metal levels were evaluated in sediments in accordance with the numerical SQG of the USEPA. The levels of fish tissues were lower than the results reported from polluted areas of the Mediterranean. The highest BAFs were detected for Hg and Cd in fish.

  7. Geographic patterns of elemental deposition in the Aegean region of Turkey indicated by the lichen, Xanthoria parietina (L.) Th. Fr.

    PubMed

    Yenisoy-Karakaş, S; Tuncel, S G

    2004-08-15

    Lichen samples from different parts of the world have been known to accumulate elements to a greater degree than higher plants, if they are exposed to these elements from the atmosphere or from water and sediments. It has been hypothesized that lichens can be used to monitor air pollution around point and area emission sources. Local variation (variation in substrate, age and morphology of lichen samples) of element concentrations would not be large enough to affect the concentration patterns in large areas. We tested this hypothesis in the Aegean region of Turkey, which is very urbanized and industrialized. No such study has been conducted before in this part of the country. A total of 234 samples of the lichen Xanthoria parietina were collected from a 51,800-km2 area. Samples were washed and analyzed by INAA and ICP-AES for 35 elements. The range of the concentrations for most of the elements on a local scale was an order of magnitude lower than for the element concentrations on a regional scale. The mean local coefficient of variance (CV) was found to be 15, providing that the local variation did not affect the concentration of elements in the sampling region. According to cluster analysis, 8 (As, Hg, Pb, Sb, Fe, Mn, Na and K) elements are indicative of important local pollution locations and their zone of impact in the region. By mapping the concentrations of eight indicative elements in lichen Xanthoria parietina of the Aegean region, it was possible to relate deposition to the existence of known sources of pollution in certain areas. Location of pollution sources such as iron-steel plants, and coal burning in the cities, industrial activity and two important coal-fired power plants generally corresponded with locations of highest element accumulations in the lichens.

  8. The North Cycladic Detachment System and associated mineralization, Mykonos, Greece: Insights on the evolution of the Aegean domain

    NASA Astrophysics Data System (ADS)

    Menant, Armel; Jolivet, Laurent; Augier, Romain; Skarpelis, Nikolaos

    2013-06-01

    the Aegean back-arc domain, some 30-35 Ma ago, an increase of the rate of slab retreat led to the initiation of post-orogenic extension, largely accommodated by large-scale structures such as the North Cycladic Detachment System (NCDS). Although this extension is still active nowadays, an E-W compressional regime developed in the Late Miocene with the propagation of the North Anatolian Fault. On Mykonos island (Cyclades), the NE-SW back-arc extension is particularly well expressed with the Livada and Mykonos detachments that belong to the NCDS and that are associated with NW-SE barite veins emplaced during the synkinematic cooling of the Mykonos intrusion. This study shows that the formation of the mineralization occurred when the pluton crossed the ductile-to-brittle transition during its exhumation below the NCDS at ~11-10 Ma. In addition, the kinematics of mineralized structures evolved with time: (1) most of the displacement was accommodated by the top-to-the-NE Livada and Mykonos detachments accompanied by the formation of mineralized normal faults that were (2) reworked in a strike-slip regime with an E-W direction of shortening and a persistent NE-SW stretching and (3) a late post-mineralization E-W compressional stage with a minor reworking of shallow-dipping faults (locally including the detachments themselves). We interpret this increase of the E-W shortening component recorded during the mineral deposition as a consequence of the initiation of the westward motion of Anatolia from 10 Ma, thus 4 Ma before the propagation of the North Anatolian Fault in the Dardanelles Strait and the localization of the strain on the Aegean Sea margins.

  9. Forecasting skill assessment of an oil spill simulation system in the NE Aegean and atmospheric forcing perturbation experiments

    NASA Astrophysics Data System (ADS)

    Kailas, Marios; Chrysagi, Eyrydice; Sofianos, Sarantis

    2016-04-01

    In the present study, the predictive skill of an oil spill simulation system implemented in the Northern Aegean Sea was evaluated using field observations from surface drifters, provided in the framework of the TOSCA project. The system produces satisfactory results as in most cases the forecasting error is quite small, allowing the operational use of the forecast. In order to examine the sensitivity of the forecast to atmospheric forcing, additional simulations with perturbed atmospheric conditions were performed, using a time-shifting technique. In most experiments the differences between the simulations are relatively small, most likely due to slow oceanic response to variations in the wind fields. From the individual simulations an ensemble forecast was created, the results of which were also compared with the observations. The results suggest that by applying this method a safer forecast can be provided, especially regarding cases for which the wind-driven circulation is predominant. However, in cases where the circulation is characterized by intense velocity gradients (in the NE Aegean this is associated with the thermohaline front created by the Black Sea Water inflow), larger differences are present. They are related to imprecise representation of the location of the front. In these cases, the ensemble method produced no significant improvement since the relatively small differences between the trajectories of the ensemble members indicate that the position of the front in not significantly affected by the wind perturbations, based on the spatio-temporal scales examined. It is concluded that in regions with large spatio-temporal variability, an ensemble forecast produced by simulations generated from perturbed initial conditions could possibly lead to more robust results.

  10. Inferences on the Mesozoic evolution of the North Aegean from the isotopic record of the Chalkidiki block

    NASA Astrophysics Data System (ADS)

    Kydonakis, Konstantinos; Brun, Jean-Pierre; Poujol, Marc; Monié, Patrick; Chatzitheodoridis, Elias

    2016-07-01

    The Chalkidiki block is a major domain in the North Aegean that, contrary to other domains in the region, largely escaped thermal perturbations during Tertiary extension. As a result, the Chalkidiki block is an ideal candidate to glean information related to the timing of Mesozoic thermal events using appropriate geochronological techniques. We have undertaken a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) study (U-Th-Pb on monazites and U-Pb on zircons) coupled with 40Ar/39Ar dating on nine samples from various structural levels within the thrust system of the Chalkidiki block. The eastern, and structurally lower part of the system revealed a complete isotopic reset of Carboniferous - Early Triassic monazites coeval with partial monazite destruction, REE-mobilisation and formation of apatite-allanite-epidote coronas at ~ 132 Ma, a reaction that is commonly observed in amphibolite-facies rocks. These coronas formed after crystallisation of garnet (i.e., at T > 580 °C) and, in all probability, either close to the peak-temperature conditions (~ 620 °C) on a prograde path or during retrogression between the peak-temperature and the low-temperature boundary of the amphibolite facies. Cooling of these rocks and arrival at mid-crustal levels occurred at 95-100 Ma. By contrast, the western, and structurally uppermost part of the system went through the same event by 120-125 Ma. Further structural considerations with respect to medium-temperature geochronology data imply that syn-metamorphic thrusting must have ceased by early Late Cretaceous. We emphasize that, with the sole exception of the Chalkidiki block, no pre-45 Ma medium-temperature geochronology data are preserved in other North Aegean domains, a feature that is clearly related to the extension-induced thermal perturbation of the region during the Tertiary.

  11. Particulate organic carbon export fluxes and size-fractionated POC/ 234Th ratios in the Ligurian, Tyrrhenian and Aegean Seas

    NASA Astrophysics Data System (ADS)

    Speicher, E. A.; Moran, S. B.; Burd, A. B.; Delfanti, R.; Kaberi, H.; Kelly, R. P.; Papucci, C.; Smith, J. N.; Stavrakakis, S.; Torricelli, L.; Zervakis, V.

    2006-11-01

    Measurements of 234Th/ 238U disequilibria and particle size-fractionated (1, 10, 20, 53, 70, 100 μm) organic C and 234Th were made to constrain estimates of the export flux of particulate organic C (POC) from the surface waters of the Ligurian, Tyrrhenian and Aegean Seas in March-June 2004. POC exported from the surface waters (75-100 m depth) averaged 9.2 mmol m -2 d -1 in the Ligurian and Tyrrhenian Seas (2.3±0.5-14.9±3.0 mmol m -2 d -1) and 0.9 mmol m -2 d -1 in the Aegean Sea. These results are comparable to previous measurements of 234Th-derived and sediment-trap POC fluxes from the upper 200 m in the Mediterranean Sea. Depth variations in the POC/ 234Th ratio suggest two possible controls. First, decreasing POC/ 234Th ratios with depth were attributed to preferential remineralization of organic C. Second, the occurrence of maxima or minima in the POC/ 234Th ratio near the DCM suggests influence by phytoplankton dynamics. To assess the accuracy of these data, the empirical 234Th-method was evaluated by quantifying the extent to which the 234Th-based estimate of POC flux, PPOC, deviates from the true flux, FPOC, defined as the p-ratio ( p-ratio= PPOC/FPOC= STh/SPOC, where S=particle sinking rate). Estimates of the p-ratio made using Stokes' Law and the particle size distributions of organic C and 234Th yield values ranging from 0.93-1.45. The proximity of the p-ratio to unity implies that differences in the sinking rates of POC- and 234Th-carrying particles did not bias 234Th-normalized POC fluxes by more than a factor of two.

  12. The Middle Pleistocene archaeological record of Greece and the role of the Aegean in hominin dispersals: new data and interpretations

    NASA Astrophysics Data System (ADS)

    Tourloukis, Vangelis; Karkanas, Panagiotis

    2012-06-01

    In the debate about hominin dispersals, Greece is expected to have been among the core areas for the peopling of Eurasia, serving as a 'refugium' and source region for (re)colonizations. Yet, its early Pleistocene record is still scarce, forming a conspicuous 'gap' in the early human geography of the Mediterranean. Here we investigate this gap and provide for the first time a synthesis of the Lower Palaeolithic record of Greece. Our study adopts a geoarchaeological approach to explain the current status of the record and argues that the 'absence of evidence' should be understood as the result of the biasing effects of erosional geomorphic processes and not as an indication of a former absence of hominins. In this line, the potential for archaeological preservation and recovery is assessed as a function of landscape dynamics. Climatic seasonality, tectonic activity, high relief and marine inundations have altogether contributed to significant reworking and/or total loss of archaeological sites: in spatial terms, only about 2-5% of the Lower Palaeolithic record of Greece may have survived up to the present. On the other hand, we interpret recent geological data, which show that half of the Aegean Sea would have been subaerially exposed for most of the early Pleistocene. Our results emphasize the potentially central role of the Aegean region in hominin dispersals, both as a biogeographical landbridge and as a highly productive landscape for occupation. This conclusion opens up new prospects for future fieldwork in an area that was hitherto essentially neglected. Finally, in showing how geomorphic processes bias site distribution patterns, the results and methodological perspective developed here can be seen as having implications that are wider than the geographical limits of the Greek Peninsula: they are pertinent to the investigation and interpretation of the early Pleistocene archaeological records in the highly dynamic landscapes of southern Europe - if not in

  13. Late cretaceous extensional tectonics and associated igneous activity on the northern margin of the Gulf of Mexico Basin

    NASA Technical Reports Server (NTRS)

    Bowen, R. L.; Sundeen, D. A.

    1985-01-01

    Major, dominantly compressional, orogenic episodes (Taconic, Acadian, Alleghenian) affected eastern North America during the Paleozoic. During the Mesozoic, in contrast, this same region was principally affected by epeirogenic and extensional tectonism; one episode of comparatively more intense tectonic activity involving extensive faulting, uplift, sedimentation, intrusion and effusion produced the Newark Series of eposits and fault block phenomena. This event, termed the Palisades Disturbance, took place during the Late Triassic - Earliest Jurassic. The authors document a comparable extensional tectonic-igneous event occurring during the Late Cretaceous (Early Gulfian; Cenomanian-Santonian) along the southern margin of the cratonic platform from Arkansas to Georgia.

  14. Present-day deformation across the Basin and Range Province, western United States

    USGS Publications Warehouse

    Thatcher, W.; Foulger, G.R.; Julian, B.R.; Svarc, J.; Quilty, E.; Bawden, G.W.

    1999-01-01

    The distribution of deformation within the Basin and Range province was determined from 1992, 1996, and 1998 surveys of a dense, 800-kilometer- aperture, Global Positioning System network, Internal deformation generally follows the pattern of Holocene fault distribution and is concentrated near the western extremity of the province, with lesser amounts focused near the eastern boundary. Little net deformation occurs across the central 500 kilometers of the network in western Utah and eastern Nevada. Concentration of deformation adjacent to the rigid Sierra Nevada block indicates that external plate-driving forces play an important role in driving deformation, modulating the extensional stress field generated by internal buoyancy forces that are due to lateral density gradients and topography near the province boundaries.

  15. The influence of regional extensional tectonic stress on the eruptive behaviour of subduction-zone volcanoes

    NASA Astrophysics Data System (ADS)

    Tost, M.; Cronin, S. J.

    2015-12-01

    Regional tectonic stress is considered a trigger mechanism for explosive volcanic activity, but the related mechanisms at depth are not well understood. The unique geological setting of Ruapehu, New Zealand, allows investigation on the effect of enhanced regional extensional crustal tension on the eruptive behaviour of subduction-zone volcanoes. The composite cone is located at the southwestern terminus of the Taupo Volcanic Zone, one of the most active silicic magma systems on Earth, which extends through the central part of New Zealand's North Island. Rhyolitic caldera eruptions are limited to its central part where crustal extension is highest, whereas lower extension and additional dextral shear dominate in the southwestern and northeastern segments characterized by andesitic volcanism. South of Ruapehu, the intra-arc rift zone traverses into a compressional geological setting with updoming marine sequences dissected by reverse and normal faults. The current eruptive behaviour of Ruapehu is dominated by small-scaled vulcanian eruptions, but our studies indicate that subplinian to plinian eruptions have frequently occurred since ≥340 ka and were usually preceded by major rhyolitic caldera unrest in the Taupo Volcanic Zone. Pre-existing structures related to the NNW-SSE trending subduction-zone setting are thought to extend at depth and create preferred pathways for the silicic magma bodies, which may facilitate the development of large (>100 km3) dyke-like upper-crustal storage systems prior to major caldera activity. This may cause enhanced extensional stress throughout the entire intra-arc setting, including the Ruapehu area. During periods of caldera dormancy, the thick crust underlying the volcano and the enhanced dextral share rate likely impede ascent of larger andesitic magma bodies, and storage of andesitic melts dominantly occurs within small-scaled magma bodies at middle- to lower-crustal levels. During episodes of major caldera unrest, ascent and

  16. Dynamics of concentric and eccentric compound droplets suspended in extensional flows

    NASA Astrophysics Data System (ADS)

    Qu, Xiaofeng; Wang, Yechun

    2012-12-01

    The motion, deformation, and stability of compound droplets in extensional flows are investigated numerically via a three-dimensional spectral boundary element method. We examine the droplet stability under the influences of the capillary number, the inner droplet size and the relative magnitude of the surface tension of the two interfaces composing the compound droplet. The influence of viscosity on the droplet deformation is also discussed. We conclude that a compound droplet with a larger inner droplet and/or smaller inner surface tension is less stable and cannot withstand strong flow. For moderate viscosity ratios, a compound droplet with a more viscous "shell" exhibits larger deformation at steady state. In addition, for an eccentric compound droplet, both the inner and outer droplets tend to migrate away from its original location due to the asymmetry of the problem. The initial location of the inner droplet also influences the droplet stability as well as the migration velocity of the compound droplet.

  17. Isostatic uplift, crustal attenuation, and the evolution of an extensional detachment system in southwestern Nevada

    SciTech Connect

    Scott, R.B.

    1987-12-31

    Geological and geophysical evidence supports the existence of extensional detachments, between the Sheep Range and Death Valley. It is proposed that geographically separated pieces of detachments between Death Valley and the Sheep Range are parts of a regional detachment system that has evolved since the Miocene, and that the system consists of lenses of strata separated by an anastomosing network of low- and high-angle normal faults. This manuscript emphasizes the probability that isostatic uplift within the region of greatest crustal attenuation in this system, the Bullfrog Hills core complex, controlled the evolution of the detachment system between the breakaway zone a the Sheep Range and the core complex. Features in this system are described from east to west, which is the apparent direction of tectonic transport.

  18. Voltage preamplifier for extensional quartz sensors used in scanning force microscopy.

    PubMed

    Morawski, Ireneusz; Blicharski, Józef; Voigtländer, Bert

    2011-06-01

    Extensional-mode quartz resonators are being increasingly used as force sensors in dynamic scanning force microscopy or atomic force microscopy (AFM). We propose a voltage preamplifier in order to amplify the charge induced on quartz electrodes. The proposed solution has some advantages over the typically used current-to-voltage converters. First, the gain does not depend on the inner parameters of the quartz resonator, which are usually unknown for the specific resonator and may even vary during the measurement. Second, with such an amplifier a better signal-to-noise ratio can be achieved. Finally, we present AFM images of the Si(111) and the SiO(2) surfaces obtained by the voltage preamplifier with simultaneously recorded tunneling current.

  19. Why does near ridge extensional seismicity occur primarily in the Indian Ocean?

    NASA Technical Reports Server (NTRS)

    Stein, Seth; Cloetingh, Sierd; Wortel, Rinus; Wiens, Douglas A.

    1987-01-01

    It is argued that though thermoelastic stresses provide a low level background in all plates, the data favoring their contributing significantly to the stress field and seismicity in the young oceanic lithosphere may be interpreted in terms of stresses resulting from individual plate geometry and local boundary effects. The dramatic concentration of extensional seismicity in the Central Indian Ocean region is shown to be consistent with finite element results for the intraplate stress incorporating the effects of the Himalayan collision and the various subduction zones. Most of the data for both ridge-parallel extension and depth stratification are provided by earthquakes in this area, and it is suggested that these effects may be due more to the regional stress.

  20. Tertiary basin development and tectonic implications, Whipple detachment system, Colorado River extensional corridor, California and Arizona

    NASA Technical Reports Server (NTRS)

    Nielson, J. E.; Beratan, K. K.

    1990-01-01

    This paper reports on geologic mapping, stratigraphic and structural observations, and radiometric dating of Miocene deposits of the Whipple detachment system, Colorado River extensional corridor of California and Arizona. From these data, four regions are distinguished in the study area that correspond to four Miocene depositional basins. It is shown that these basins developed in about the same positions, relative to each other and to volcanic sources, as they occupy at present. They formed in the early Miocene from a segmentation of the upper crust into blocks bounded by high-angle faults that trended both parallel and perpendicular to the direction of extension and which were terminated at middle crustal depths by a low-angle detachment fault.

  1. A Geothermal GIS for Nevada: Defining Regional Controls and Favorable Exploration Terrains for Extensional Geothermal Systems

    USGS Publications Warehouse

    Coolbaugh, M.F.; Taranik, J.V.; Raines, G.L.; Shevenell, L.A.; Sawatzky, D.L.; Bedell, R.; Minor, T.B.

    2002-01-01

    Spatial analysis with a GIS was used to evaluate geothermal systems in Nevada using digital maps of geology, heat flow, young faults, young volcanism, depth to groundwater, groundwater geochemistry, earthquakes, and gravity. High-temperature (>160??C) extensional geothermal systems are preferentially associated with northeast-striking late Pleistocene and younger faults, caused by crustal extension, which in most of Nevada is currently oriented northwesterly (as measured by GPS). The distribution of sparse young (160??C) geothermal systems in Nevada are more likely to occur in areas where the groundwater table is shallow (<30m). Undiscovered geothermal systems may occur where groundwater levels are deeper and hot springs do not issue at the surface. A logistic regression exploration model was developed for geothermal systems, using young faults, young volcanics, positive gravity anomalies, and earthquakes to predict areas where deeper groundwater tables are most likely to conceal geothermal systems.

  2. Two touching spherical drops in uniaxial extensional flow: analytic solution to the creeping flow problem.

    PubMed

    Baldessari, Fabio; Leal, L Gary

    2005-09-01

    We solve the problem of the creeping motion of a uniaxial extensional flow past two touching spherical drops when the line of centers is parallel to the axis of symmetry of the flow, using tangent sphere coordinates. We apply this solution to the case of two equal size drops. It provides an exact result for the equal and opposite force acting on each drop along the line of centers. We also use it to determine the magnitude of the internal recirculating flow in the vicinity of the rear stagnation point, which can be used to evaluate the importance of this flow on the film drainage process for two (nearly) touching drops in a coalescence process for the limiting case, Ca < 1.

  3. Transpressive inversion of a Mesozoic extensional forced fold system with an intermediate décollement level in the Basque-Cantabrian Basin (Spain)

    NASA Astrophysics Data System (ADS)

    Tavani, Stefano; Carola, Eloi; Granado, Pablo; Quintã, Anna; MuñOz, Josep Anton

    2013-03-01

    In the Basque-Cantabrian Basin (Spain), normal faulting and associated folding occurred during Late Jurassic to Early Cretaceous rifting. Cenozoic Pyrenean thick-skinned transpressive inversion in the western parts of the basin preserved the first-order extensional architecture. Integration of geological maps and seismic profiles has permitted to fully constrain the style of extensional deformation and subsequent inversion in the western portion of the Basque-Cantabrian Basin. Extensional faults offset the Paleozoic basement up to Lower Triassic rocks. The presence of an efficient décollement level represented by Triassic evaporites produced the decoupling between basement rocks and the Upper Triassic to Middle Jurassic prerift cover sequence. Extensional forced folding occurred in the cover, driven by basement faulting and the migration of evaporites toward the hanging wall of the extensional faults, with salt welds developing away from them. Upper Jurassic to Lower Cretaceous syn-rift sediments deposited synchronously with forced folding, which led to the development of extensional growth geometries associated with both master faults and nearly-transverse faults. Syn-rift growth sequences are characterized by downlap and onlap relationships with the underlying prerift units, interpreted as the result of along-strike variations of master fault extensional displacement rate. Cenozoic Pyrenean contraction generated the right-lateral transpressive inversion of basement master faults and the almost dip-slip reactivation of transverse extensional faults.

  4. Structural Evolution of a Large Extensional Basin Near Charleston, SC, Illuminated By Seismic-Reflection Profiling

    NASA Astrophysics Data System (ADS)

    Beale, J. N.; Chapman, M. C.

    2009-12-01

    A comprehensive re-examination and reprocessing of 1980s-vintage seismic-reflection data collected near Charleston, South Carolina, which lies within the South Georgia Rift, has revealed evidence of significant crustal extension and coeval magmatic activity, as well as apparent basin inversion and a late-stage episode of mafic volcanism. The South Georgia Rift is comprised of several large extensional basins separated by intervening structural highs, and is a failed Triassic-Jurassic rift separating the Appalachian Piedmont terrane to the north from the Suwannee terrane to the south. Gravity and magnetic modeling indicate that a significant amount of mafic rock lies within the upper crust near Charleston. Seismic profiles show bright reflections within the early-Mesozoic basement rock beneath the Atlantic Coastal Plain sediments that probably represent the interface between clastic sediments and basalt layers. These basalt layers have been sparsely sampled by deep drilling within the South Georgia Rift. The seismic data from Charleston, together with crustal scale, seismic-reflection data from Georgia, show the evolution of the rifting process from the extensional phase which produced the large basins and high rates of sedimentation, through the compressional phase which produced uplift and erosion leading to an inverted basin geometry. Additionally, in the Charleston area, the seismic data show a basalt layer that forms the post-rift unconformity over most of the area. This basalt layer is not present on most of the profiles in Georgia, where the base of the coastal plain sediments is rift-related sedimentary rock. Significantly, near Charleston this basalt layer lacks the large amount of deformation that is characteristic of all of the imaged basalt layers beneath it. This suggests that there is a significant separation in time between the syn-rift basalt layers and the apparently post-rift basalt layer at the top of the rift sequence.

  5. Cenozoic contractional reactivation of Mesozoic extensional structures in the Eastern Cordillera of Colombia

    NASA Astrophysics Data System (ADS)

    Mora, AndréS.; Parra, Mauricio; Strecker, Manfred R.; Kammer, Andreas; Dimaté, Cristina; RodríGuez, Fernando

    2006-04-01

    The Eastern Cordillera of Colombia is key to understanding the role of inherited basement anisotropies in the evolution of active noncollisional mountain belts. In particular, the Rio Blanco-Guatiquía region of the Eastern Cordillera is exemplary in displaying a variety of phenomena that document the importance of the orientation, geometry, and segmentation of preorogenic anisotropies. We document the first unambiguous evidence that extensional basement structures played an important role in determining the locus of deformation during contractional reactivation in the Eastern Cordillera. Detailed structural field mapping and analysis of industry seismic reflection profiles have helped to identify the inherited San Juanito, Naranjal, and Servitá normal faults and associated transfer faults as important structures that were inverted during the Cenozoic Andean orogeny. Apparently, the more internal faults in the former rift basin were not properly oriented for an efficient reactivation in contraction. However, these faults have a fundamental role as strain risers, as folding is concentrated west of them. In contrast, reactivated normal faults such as the more external Servitá fault are responsible for uplifting the eastern flank of the Eastern Cordillera. In addition, these structures are adjacent and intimately linked to the development of thin-skinned faults farther east. In part, the superimposed compression in this prestrained extensional region is compensated by lateral escape. The dominant presence of basement involved buckling and thrusting, and the restricted development of thin-skinned thrusting in this inversion orogen makes the Eastern Cordillera a close analog to the intraplate Atlas Mountains of Morocco and other inverted sectors of the Andean orogen farther south.

  6. Rift tectonics of the Polis extensional graben, N. W. Cyprus, and associated traps

    SciTech Connect

    Ward, L.C. )

    1988-08-01

    The Polis extensional graben, northwest Cyprus, is located west of the Troodos ophiolite massif and east of the Akamas Peninsula. It outcrops 35 km onland before trending offshore into the Cilician basin. From field studies, geophysical and seismic data, and NASA shuttle photos, the graben is seen to be asymmetric in cross section, trending north-northwest-south-southeast, and is of Miocene-Holocene age. The graben is delineated by planar and listric normal faults (oriented 160{degree}/340{degree}) which dip toward the axis of the graben and have dip-slip motion from slickenside studies. The Polis graben evolved at the end of late Miocene time in response to passive rifting, as evidenced by extensional boudinage, horizontal stylolites, and multiple unconformities in older pre-upper Miocene formations. Rifting occurred in multiple phases which commenced in the north and propagated southward. These produced subsidence, preserving pre-graben traps from erosion. The graben is transected by major transverse faults which segment it into separate structural domains that control differential tilt and subsidence of blocks in the axis of the graben. Lithofacies analysis shows pre-graben traps include reefs and deposits formed in response to gravity and mass-flow events. Graben-fill sequences consist of coarse clastics at the base, deposited in braided-stream and alluvial-fan environments, superseded by deep-water facies, due to the Pliocene transgression, which include graded sands, turbidites, and mass-flow deposits and fan deltas. Traps are structured and tilted to produce roll-over anticlines and monoclinal folds.

  7. Carbonate sedimentation in an extensional active margin: Cretaceous history of the Haymana region, Pontides

    NASA Astrophysics Data System (ADS)

    Okay, Aral I.; Altiner, Demir

    2016-10-01

    The Haymana region in Central Anatolia is located in the southern part of the Pontides close to the İzmir-Ankara suture. During the Cretaceous, the region formed part of the south-facing active margin of the Eurasia. The area preserves a nearly complete record of the Cretaceous system. Shallow marine carbonates of earliest Cretaceous age are overlain by a 700-m-thick Cretaceous sequence, dominated by deep marine limestones. Three unconformity-bounded pelagic carbonate sequences of Berriasian, Albian-Cenomanian and Turonian-Santonian ages are recognized: Each depositional sequence is preceded by a period of tilting and submarine erosion during the Berriasian, early Albian and late Cenomanian, which corresponds to phases of local extension in the active continental margin. Carbonate breccias mark the base of the sequences and each carbonate sequence steps down on older units. The deep marine carbonate deposition ended in the late Santonian followed by tilting, erosion and folding during the Campanian. Deposition of thick siliciclastic turbidites started in the late Campanian and continued into the Tertiary. Unlike most forearc basins, the Haymana region was a site of deep marine carbonate deposition until the Campanian. This was because the Pontide arc was extensional and the volcanic detritus was trapped in the intra-arc basins and did not reach the forearc or the trench. The extensional nature of the arc is also shown by the opening of the Black Sea as a backarc basin in the Turonian-Santonian. The carbonate sedimentation in an active margin is characterized by synsedimentary vertical displacements, which results in submarine erosion, carbonate breccias and in the lateral discontinuity of the sequences, and differs from blanket like carbonate deposition in the passive margins.

  8. Recognizing Mantle Domains Related to an Extensional Cycle: the Record from Western Europe

    NASA Astrophysics Data System (ADS)

    Picazo, S.; Muntener, O.; Manatschal, G.

    2015-12-01

    Most of the studies on rifted margins have shown that the classical predictions of models assuming a "homogeneous" mantle lithosphere without some inheritance are unable to capture the observed large variety of magmatic budgets as a function of extension. More recently, new ideas and concepts have been developed to understand the evolution of the mantle lithosphere in hyper-extended magma-poor rifted margins that are mainly based on observations from the present-day Iberia-Newfoundland and ancient Alpine Tethys rifted margins and the Pyrenean systems. In contrast to the classical assumption assuming a simple, isotropic mantle lithosphere, these new models integrate observations from exposed and drilled mantle rocks and propose that the mantle lithosphere evolved and was modified during an extensional cycle from post-orogenic collapse through several periods of rifting to embryonic oceanic (ultra-) slow seafloor spreading. But it is, at present, unclear how far these ideas can be generalized and if they can explain the nature of mantle rocks observed across Western Europe and, in a more general way, at Atlantic type rifted margins. We review the available mantle data from Western Europe, i.e. ophiolite massifs, xenoliths and dredged samples, revisit the available terminology concerning mantle massifs and xenoliths and compile the available data to identify different mantle domains. We define chemical and petrological characteristics of mantle domains based on clinopyroxene and spinel compositions and compile them on present-day and paleo-geographic maps of Western Europe. Finally we link the observed distribution of mantle domains to the post-Variscan extensional cycle and link domains to processes related to the late post-Variscan extension, the rift evolution and refertilization associated to hyper-extension and the development of embryonic oceanic domains.

  9. Synovial fluid response to extensional flow: effects of dilution and intermolecular interactions.

    PubMed

    Haward, Simon J

    2014-01-01

    In this study, a microfluidic cross-slot device is used to examine the extensional flow response of diluted porcine synovial fluid (PSF) samples using flow-induced birefringence (FIB) measurements. The PSF sample is diluted to 10× 20× and 30× its original mass in a phosphate-buffered saline and its FIB response measured as a function of the strain rate at the stagnation point of the cross-slots. Equivalent experiments are also carried out using trypsin-treated PSF (t-PSF) in which the protein content is digested away using an enzyme. The results show that, at the synovial fluid concentrations tested, the protein content plays a negligible role in either the fluid's bulk shear or extensional flow behaviour. This helps support the validity of the analysis of synovial fluid HA content, either by microfluidic or by other techniques where the synovial fluid is first diluted, and suggests that the HA and protein content in synovial fluid must be higher than a certain minimum threshold concentration before HA-protein or protein-protein interactions become significant. However a systematic shift in the FIB response as the PSF and t-PSF samples are progressively diluted indicates that HA-HA interactions remain significant at the concentrations tested. These interactions influence FIB-derived macromolecular parameters such as the relaxation time and the molecular weight distribution and therefore must be minimized for the best validity of this method as an analytical technique, in which non-interaction between molecules is assumed.

  10. Discrete element modeling of Martian pit crater formation in response to extensional fracturing and dilational normal faulting

    NASA Astrophysics Data System (ADS)

    Smart, Kevin J.; Wyrick, Danielle Y.; Ferrill, David A.

    2011-04-01

    Pit craters, circular to elliptical depressions that lack a raised rim or ejecta deposits, are common on the surface of Mars. Similar structures are also found on Earth, Venus, the Moon, and smaller planetary bodies, including some asteroids. While it is generally accepted that these pits form in response to material drainage into a subsurface void space, the primary mechanism(s) responsible for creating the void is a subject of debate. Previously proposed mechanisms include collapse into lave tubes, dike injection, extensional fracturing, and dilational normal faulting. In this study, we employ two-dimensional discrete element models to assess both extensional fracturing and dilational normal faulting as mechanisms for forming pit craters. We also examine the effect of mechanical stratigraphy (alternating strong and weak layers) and variation in regolith thickness on pit morphology. Our simulations indicate that both extensional fracturing and dilational normal faulting are viable mechanisms. Both mechanisms lead to generally convex (steepening downward) slope profiles; extensional fracturing results in generally symmetric pits, whereas dilational normal faulting produces strongly asymmetric geometries. Pit width is established early, whereas pit depth increases later in the deformation history. Inclusion of mechanical stratigraphy results in wider and deeper pits, particularly for the dilational normal faulting, and the presence of strong near-surface layers leads to pits with distinct edges as observed on Mars. The modeling results suggest that a thicker regolith leads to wider but shallower pits that are less distinct and may be more difficult to detect in areas of thick regolith.

  11. Suppositions, Extensionality, and Conditionals: A Critique of the Mental Model Theory of Johnson-Laird and Byrne (2002)

    ERIC Educational Resources Information Center

    Evans, Jonathan St. B. T.; Over, David E.; Handley, Simon J.

    2005-01-01

    P. N. Johnson-Laird and R. M. J. Byrne proposed an influential theory of conditionals in which mental models represent logical possibilities and inferences are drawn from the extensions of possibilities that are used to represent conditionals. In this article, the authors argue that the extensional semantics underlying this theory is equivalent to…

  12. Chemical properties and fluorescence of DOM in relation to biodegradation in the interconnected Marmara-North Aegean Seas during August 2008

    NASA Astrophysics Data System (ADS)

    Zeri, C.; Beşiktepe, Ş.; Giannakourou, A.; Krasakopoulou, E.; Tzortziou, M.; Tsoliakos, D.; Pavlidou, A.; Mousdis, G.; Pitta, E.; Scoullos, M.; Papathanassiou, E.

    2014-07-01

    The dynamics of dissolved organic matter (DOM) in the Marmara Sea-Dardanelles Straits-North Aegean Sea were investigated using measurements of dissolved organic carbon and nitrogen (DOC, DON), PARAFAC modeling of 3-D excitation-emission fluorescence spectra and bacterial production (BP) and respiration (BR) rates. In the surface brackish waters, chemical parameters showed an increase from the Aegean to the Marmara (DOC: 65-217 μmol L- 1; DON: 3.08-9.34 μmol L- 1; Dissolved Inorganic Nitrogen (DIN): 0.044-1.38), followed by an increase in BP rates (7.2-195 nmol L- 1 d- 1). In the subsurface waters, DIN also showed an increase in the Marmara basin (0.085-9.79 μmol L- 1) followed by an increase in BP rates (3.3-17.4 nmol L- 1 d- 1). PARAFAC modeling revealed three fluorescent components: λex/λem: < 260(330)/464 nm, humic-like; λex/λem: <(260) 285/364 nm, quinone-like; λex/λem: 270/308 nm, tyrosine-like. DOC:DON ratios were found similar for the Marmara (21 ± 3) and the N. Aegean Sea (19 ± 2). The slopes ΔDOC:ΔDON suggested that in the Marmara Sea mineralization processes require more carbon relative to nitrogen (22.3), whereas in the N. Aegean there is preferential removal of nitrogen over carbon (5.66). The lack of significant correlation between DOC and AOU (apparent oxygen utilization) in the deep Marmara waters indicates that particulate organic matter is important in deep mineralization processes.

  13. Peeking through the trapdoor: Historical biogeography of the Aegean endemic spider Cyrtocarenum Ausserer, 1871 with an estimation of mtDNA substitution rates for Mygalomorphae.

    PubMed

    Kornilios, P; Thanou, E; Kapli, P; Parmakelis, A; Chatzaki, M

    2016-05-01

    The Aegean region, located in the Eastern Mediterranean, is an area of rich biodiversity and endemism. Its position, geographical configuration and complex geological history have shaped the diversification history of many animal taxa. Mygalomorph spiders have drawn the attention of researchers, as excellent model systems for phylogeographical investigations. However, phylogeographic studies of spiders in the Aegean region are scarce. In this study, we focused on the phylogeography of the endemic ctenizid trap-door spider Cyrtocarenum Ausserer, 1871. The genus includes two morphologically described species: C. grajum (C.L. Koch, 1836) and C. cunicularium (Olivier, 1811). We sampled 60 specimens from the distributions of both species and analyzed four mitochondrial and two nuclear markers. Cyrtocarenum served as an example to demonstrate the importance of natural history traits in the inference of phylogeographic scenarios. The mtDNA substitution rates inferred for the genus are profoundly higher compared to araneomorph spiders and other arthropods, which seems tightly associated with their biology. We evaluate published mtDNA substitution rates followed in the literature for mygalomorph spiders and discuss potential pitfalls. Following gene tree (maximum likelihood, Bayesian inference) and species tree approaches ((*)BEAST), we reconstructed a time-calibrated phylogeny of the genus. These results, combined with a biogeographical ancestral-area analysis, helped build a biogeographic scenario that describes how the major palaeogeographic and palaeoclimatic events of the Aegean may have affected the distribution of Cyrtocarenum lineages. The diversification of the genus seems to have begun in the Middle Miocene in the present west Aegean area, while major phylogenetic events occurred at the Miocene-Pliocene boundary for C. cunicularium, probably related to the Messinian Salinity Crisis. Our results also demonstrate the clear molecular distinction of the two

  14. Variation of the Earth tide-seismicity compliance parameter the last 50 years for the west site of the Aegean Volcanic Arc, Greece

    NASA Astrophysics Data System (ADS)

    Contadakis, M. E.; Arabelos, D. N.; Vergos, G.; Spatalas, S.

    2015-07-01

    Based on the results of our studies for the tidal triggering effect on the seismicity of the Hellenic area, we consider the confidence level of earthquake occurrence - tidal period accordance as an index of tectonic stress criticality for earthquake occurrence and we check if the recent increase in the seismic activity at the west site of the Aegean Volcanic Arc indicate faulting maturity for a stronger earthquake. In this paper we present the results of this test which are positive.

  15. Foraminifera eco-biostratigraphy of the southern Evoikos outer shelf, central Aegean Sea, during MIS 5 to present

    NASA Astrophysics Data System (ADS)

    Drinia, Hara; Antonarakou, Assimina; Tsourou, Theodora; Kontakiotis, George; Psychogiou, Maria; Anastasakis, George

    2016-09-01

    The South Evoikos Basin is a marginal basin in the Aegean Sea which receives little terrigenous supply and its sedimentation is dominated by hemipelagic processes. Late Quaternary benthic and planktonic foraminifera from core PAG-155 are investigated in order to understand their response to the glacial-interglacial cycles in this region. The quantitative analysis of planktonic foraminifera, coupled with accelerator mass spectrometry (14C-AMS) radiocarbon date measurements, provide an integrated chrono-stratigraphic time framework over the last 90 ka (time interval between late Marine Isotopic Stages 5 and 1; MIS5-MIS1). The temporary appearance and disappearance as well as several abundance peaks in the quantitative distribution of selected climate-sensitive planktonic species allowed the identification of several eco-bioevents, useful to accurately mark the boundaries of the eco-biozones widely recognized in the Mediterranean records and used for large-scale correlations. The established bio-ecozonation scheme allows a detailed palaecological reconstruction for the late Pleistocene archive in the central Aegean, and furthermore provides a notable contribution for palaeoclimatic studies, facilitating intercorrelations between various oceanographic basins. The quantitative analyses of benthic foraminifera identify four distinct assemblages, namely Biofacies: Elphidium spp., Haynesina spp. Biofacies, characterized by neritic species, dominated during the transition from MIS 5 to MIS 4; Cassidulina laevigata/carinata Biofacies dominated till 42 ka (transgressive trend from MIS 4 to MIS 3); Bulimina gibba Biofacies dominated from 42 ka to 9.5 ka (extensive regression MIS 3,2 through lowstand and early transgression; beginning of MIS 1); Bulimina marginata, Uvigerina spp. Biofacies dominated from 9.5 ka to the present (late transgression through early highstand; MIS 1)., This study showed that the South Evoikos Basin which is characterized by its critical depths and

  16. Review of variations in Mw < 7 earthquake motions on position and TEC (Mw = 6.5 Aegean Sea earthquake sample)

    NASA Astrophysics Data System (ADS)

    Yildirim, Omer; Inyurt, Samed; Mekik, Cetin

    2016-02-01

    Turkey is a country located in the middle latitude zone, where tectonic activity is intensive. Recently, an earthquake of magnitude 6.5 Mw occurred offshore in the Aegean Sea on 24 May 2014 at 09:25 UTC, which lasted about 40 s. The earthquake was also felt in Greece, Romania, and Bulgaria in addition to Turkey. In recent years, ionospheric anomaly detection studies have been carried out because of seismicity with total electron content (TEC) computed from the global navigation satellite system's (GNSS) signal delays and several interesting findings have been published. In this study, both TEC and positional variations have been examined separately following a moderate size earthquake in the Aegean Sea. The correlation of the aforementioned ionospheric variation with the positional variation has also been investigated. For this purpose, a total of 15 stations was used, including four continuously operating reference stations in Turkey (CORS-TR) and stations in the seismic zone (AYVL, CANA, IPSA, and YENC), as well as international GNSS service (IGS) and European reference frame permanent network (EPN) stations. The ionospheric and positional variations of the AYVL, CANA, IPSA, and YENC stations were examined using Bernese v5.0 software. When the precise point positioning TEC (PPP-TEC) values were examined, it was observed that the TEC values were approximately 4 TECU (total electron content unit) above the upper-limit TEC value at four stations located in Turkey, 3 days before the earthquake at 08:00 and 10:00 UTC. At the same stations, on the day before the earthquake at 06:00, 08:00, and 10:00 UTC, the TEC values were approximately 5 TECU below the lower-limit TEC value. The global ionosphere model TEC (GIM-TEC) values published by the Centre for Orbit Determination in Europe (CODE) were also examined. Three days before the earthquake, at all stations, it was observed that the TEC values in the time period between 08:00 and 10:00 UTC were approximately 2 TECU

  17. Review of variations in Mw < 7 earthquake motions on position and tec (Mw = 6.5 aegean sea earthquake sample)

    NASA Astrophysics Data System (ADS)

    Yildirim, O.; Inyurt, S.; Mekik, C.

    2015-10-01

    Turkey is a country located in Middle Latitude zone and in which tectonic activity is intensive. Lastly, an earthquake of magnitude 6.5Mw occurred at Aegean Sea offshore on date 24 May 2014 at 12:25 UTC and it lasted approximately 40 s. The said earthquake was felt also in Greece, Romania and Bulgaria in addition to Turkey. In recent years seismic origin ionospheric anomaly detection studies have been done with TEC (Total Electron Contents) generated from GNSS (Global Navigation Satellite System) signals and the findings obtained have been revealed. In this study, TEC and positional variations have been examined seperately regarding the earthquake which occurred in the Aegean Sea. Then The correlation of the said ionospheric variation with the positional variation has been investigated. For this purpose, total fifteen stations have been used among which the data of four numbers of CORS-TR stations in the seismic zone (AYVL, CANA, IPSA, YENC) and IGS and EUREF stations are used. The ionospheric and positional variations of AYVL, CANA, IPSA and YENC stations have been examined by Bernese 5.0v software. When the (PPP-TEC) values produced as result of the analysis are examined, it has been understood that in the four stations located in Turkey, three days before the earthquake at 08:00 and 10:00 UTC, the TEC values were approximately 4 TECU above the upper limit TEC value. Still in the same stations, one day before the earthquake at 06:00, 08:00 and 10:00 UTC, it is being shown that the TEC values were approximately 5 TECU below the lower limit TEC value. On the other hand, the GIM-TEC values published by the CODE center have been examined. Still in all stations, it has been observed that three days before the earthquake the TEC values in the time portions of 08:00 and 10:00 UTC were approximately 2 TECU above, one day before the earthquake at 06:00, 08:00 and 10:00 UTC, the TEC values were approximately 4 TECU below the lower limit TEC value. Again, by using the same

  18. Droplet Deformation in an Extensional Flow: The Role of Surfactant Physical Chemistry

    NASA Technical Reports Server (NTRS)

    Stebe, Kathleen J.

    1996-01-01

    Surfactant-induced Marangoni effects strongly alter the stresses exerted along fluid particle interfaces. In low gravity processes, these stresses can dictate the system behavior. The dependence of Marangoni effects on surfactant physical chemistry is not understood, severely impacting our ability to predict and control fluid particle flows. A droplet in an extensional flow allows the controlled study of stretching and deforming interfaces. The deformations of the drop allow both Marangoni stresses, which resist tangential shear, and Marangoni elasticities, which resist surface dilatation, to develop. This flow presents an ideal model system for studying these effects. Prior surfactant-related work in this flow considered a linear dependence of the surface tension on the surface concentration, valid only at dilute surface concentrations, or a non-linear framework at concentrations sufficiently dilute that the linear approximation was valid. The linear framework becomes inadequate for several reasons. The finite dimensions of surfactant molecules must be taken into account with a model that includes surfaces saturation. Nonideal interactions between adsorbed surfactant molecules alter the partitioning of surfactant between the bulk and the interface, the dynamics of surfactant adsorptive/desorptive exchange, and the sensitivity of the surface tension to adsorbed surfactant. For example, cohesion between hydrocarbon chains favors strong adsorption. Cohesion also slows the rate of desorption from interfaces, and decreases the sensitivity of the surface tension to adsorbed surfactant. Strong cohesive interactions result in first order surface phase changes with a plateau in the surface tension vs surface concentration. Within this surface concentration range, the surface tension is decoupled from surface concentration gradients. We are engaged in the study of the role of surfactant physical chemistry in determining the Marangoni stresses on a drop in an extensional

  19. Anatomy of an extensional shear zone in the mantle, Lanzo massif, Italy

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Mary-Alix; Tommasi, AndréA.

    2011-08-01

    Analysis of the microstructures in the km-scale mantle shear zone that separates the northern and the central parts of the Lanzo peridotite massif provides evidence of an evolution in time and space of deformation processes accommodating shearing in the shallow mantle within an extensional setting. This shear zone displays an asymmetric distribution of deformation facies. From south to north, gradual reorientation of the foliation of coarse porphyroclastic plagioclase-bearing peridotites is followed by development of protomylonites, mylonites, and mm-scale ultramylonite bands. A sharp grain size gradient marks the northern boundary. Early deformation under near-solidus conditions in the south is recorded by preservation of weakly deformed interstitial plagioclase and almost random clinopyroxene and plagioclase crystal orientations. Feedback between deformation and melt transport probably led to melt focusing and strain weakening in the shear zone. Overprint of melt-rock reaction microstructures by solid-state deformation and decrease in recrystallized grain size in the protomylonites and mylonites indicate continued deformation under decreasing temperature. Less enriched peridotite compositions and absence of ultramafic dykes or widespread melt-impregnation microstructures north of the shear zone and clinopyroxene and amphibole enrichment in the mylonites and ultramylonites suggest that the shear zone acted as both a thermal barrier and a high-permeability channel for late crystallizing fluids. These observations, together with chemical data indicating faster cooling of central Lanzo relative to the northern body, corroborate that this shear zone is a mantle detachment fault. All deformation facies have crystal preferred orientations consistent with deformation by dislocation creep with dominant activation of the (010)[100] and (100)[001] systems in olivine and orthopyroxene, respectively. Dynamic recrystallization produces dispersion of olivine CPO but not a

  20. Temporal trends of some trace metals in Lithophaga lithophaga (L., 1758) from Izmir Bay (Eastern Aegean Sea).

    PubMed

    Ozsuer, Meral; Sunlu, Ugur

    2013-10-01

    This study compared the levels of the trace metals zinc (Zn), cadmium (Cd), lead (Pb) and copper (Cu) in the bivalve Lithophaga lithophaga from Izmir Bay (Aegean Sea) between 2001 and 2011. Comparisons were made on the basis of season, as well as year. All values were measured by voltammetry. Median values of trace metals for all seasons in 2011 were 244.67 μg Zn g(-1), 1.09 μg Cd g(-1), 7.64 μg Pb g(-1) and 56.03 μg Cu g(-1) as dry weight. The results showed a general trend of decreasing Zn, Pb and Cu concentrations over time, but an increasing trend for Cd. Mean trace metal concentrations in individuals of L. lithophaga in 2011 exceeded the permissible limit published in the Turkish Food Codex for Pb, and closely approached the limit for Zn. The mean Cd concentration was within the permissible limit of the Turkish Food Codex, but exceeded the limit of the World Health Organization. Levels of Cu were within permissible limits of published regulations.

  1. Timing of Early Proterozoic collisional and extensional events in the granulite-gneiss-charnockite-granite complex, Lake Baikal, USSR: A U-Pb, Rb-Sr, and Sm-Nd isotopic study

    SciTech Connect

    Aftalion, M. ); Bibikova, E.V. ); Bowes, D.R. ); Hopwood, A.M. ); Perchuk, L.L. )

    1991-11-01

    In the Sharyzhalgay Complex of the Lake Baikal region in eastern Siberia Early Proterozoic collisional and extensional events were separated by ca. 100 m.yr. The earlier collisional event, associated with the development of granulites and gneisses as the result of high-grade dynamothermal metamorphism, took place close to 1965 {plus minus} 4 Ma. A {sup 207}Pb/{sup 204}Pb vs. {sup 206}Pb/{sup 204}Pb isochron for zircon from five size fractions and a six point Rb-Sr whole-rock errorchron give generally corresponding ages of 1956 {plus minus} 8 and 1963 {plus minus} 163 Ma, respectively. The later extensional event, associated with charnockitization due to the uprise of fluids and heat in a regime corresponding to the middle to upper crustal levels of a Basin and Range-type province, was initiated in the 1880-1860 Ma period. The event was continued with magmatic emplacement of granitic masses into the deep levels of caldera-like structures, possibly during the upper time range of lower concordia intercept ages of 1817 +30/{minus}32 and 1797 +40/{minus}44 Ma for two distinctly different zircon populations in a pyroxene-bearing granodiorite interpreted as an evolved (and contaminated) product of the mantle-derived magma that was the source of CO{sub 2} involved in the charnockitization. Upper intercept ages of 2784 +48/{minus}45 and 2775 +61/{minus}55 Ma indicate late Archean crust at depth as the source region of the incorporated zircon. T{sub DM} ages from Sm-Nd isotopic data show that the protolith of the lithologically layered supracrustal assemblage, subsequently polyphase deformed and polymetamorphosed in Early Proterozoic times, was also formed in Early Proterozoic (not Archean) times.

  2. Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup.

    PubMed

    Keshavarz, Bavand; McKinley, Gareth H

    2016-07-01

    Understanding the elongational rheology of dilute polymer solutions plays an important role in many biological and industrial applications ranging from microfluidic lab-on-a-chip diagnostics to phenomena such as fuel atomization and combustion. Making quantitative measurements of the extensional viscosity for dilute viscoelastic fluids is a long-standing challenge and it motivates developments in microfluidic fabrication techniques and high speed/strobe imaging of millifluidic capillary phenomena in order to develop new classes of instruments. In this paper, we study the elongational rheology of a family of dilute polymeric solutions in two devices: first, steady pressure-driven flow through a hyperbolic microfluidic contraction/expansion and, second, the capillary driven breakup of a thin filament formed from a small diameter jet ([Formula: see text]). The small length scale of the device allows very large deformation rates to be achieved. Our results show that in certain limits of low viscosity and elasticity, jet breakup studies offer significant advantages over the hyperbolic channel measurements despite the more complex implementation. Using our results, together with scaling estimates of the competing viscous, elastic, inertial and capillary timescales that control the dynamics, we construct a dimensionless map or nomogram summarizing the operating space for each instrument.

  3. Midcontinent U.S. fault and fold zones: A legacy of Proterozoic intracratonic extensional tectonism?

    NASA Astrophysics Data System (ADS)

    Marshak, Stephen; Paulsen, Timothy

    1996-02-01

    The U.S. continental interior (midcontinent) contains numerous fault and fold zones. Seismic and drilling data indicate that some of these zones first formed as Proterozoic-Eocambrian rift faults, but the origin of most remains enigmatic. We propose that the enigmatic fault and fold zones also began as Proterozoic-Eocambrian normal faults. We base our hypothesis on the following: (1) enigmatic zones parallel known rifts, (2) the structural style of enigmatic zones mirrors the structural style of known rifts, (3) the map pattern of some enigmatic zones (e.g., the La Salle deformation belt of Illinois) resembles the map pattern of contemporary rifts, and (4) it is easier to rupture an intact craton by normal faulting than by reverse or strike-slip faulting. These zones, along with known rifts, represent the legacy of widespread extensional tectonism that brittlely broke up the craton into fault-bounded blocks prior to deposition of Phanerozoic platform cover. Once formed, midcontinent fault and fold zones remained weak, allowing cratonic blocks to jostle relative to one another during the Phanerozoic, thereby inverting faults (and creating transpressional or transtensional structural assemblages), localizing seismicity, and channeling (or releasing) ore-generating fluids.

  4. Extensional extrusion: Insights into south-eastward expansion of Tibetan Plateau from magnetotelluric array data

    NASA Astrophysics Data System (ADS)

    Dong, Hao; Wei, Wenbo; Jin, Sheng; Ye, Gaofeng; Zhang, Letian; Jing, Jian'en; Yin, Yaotian; Xie, Chengliang; Jones, Alan G.

    2016-11-01

    Despite extensive effort over many decades to understand the tectonic evolution of the Tibetan Plateau, the geodynamic processes creating the iconic south-eastward expansion of the plateau at the Eastern Himalayan Syntaxis (EHS) are still unclear and are hotly debated. Two popular (but not necessarily exclusive) geodynamic models, namely crustal flow at mid-to-lower crustal depths and coherent deformation between the crust and lithospheric mantle, are commonly invoked to explain the expansion mechanism. However, neither of these is able to reconcile all of the abundant geological and geophysical data. Here we present a three-dimensional (3D) geo-electrical model, derived from new SINOPROBE magnetotelluric (MT) array data, that reveals the geo-electrical, and by inference rheological, structure of southeast Tibet. Instead of NW-SE conductive channels proposed in prior two-dimensional (2D) MT studies, distinct NNE-SSW directed quasi-linear conductive anomalies are identified in the mid-to-lower crust, which are separated by a large-scale electrically resistive structure that extends from the crust to the upper mantle. This argues against the prior proposed model of south-eastward conductive anomalies, and hence against the southeast lower crust flow of material. To interpret our observations and resultant model, a new mechanism of "extensional extrusion" is proposed to address the lithospheric deformation of the south-eastward expansion of Tibetan Plateau.

  5. Salt diapirs in the Dead Sea basin and their relationship to Quaternary extensional tectonics

    USGS Publications Warehouse

    Al-Zoubi, A.; ten Brink, U.S.

    2001-01-01

    Regional extension of a brittle overburden and underlying salt causes differential loading that is thought to initiate the rise of reactive diapirs below and through regions of thin overburden. We present a modern example of a large salt diapir in the Dead Sea pull-apart basin, the Lisan diapir, which we believe was formed during the Quaternary due to basin transtension and subsidence. Using newly released seismic data that are correlated to several deep wells, we determine the size of the diapir to be 13 x 10 km. its maximum depth 7.2 km. and its roof 125 m below the surface. From seismic stratigraphy, we infer that the diapir started rising during the early to middle Pleistocene as this section of the basin underwater rapid subsidence and significant extension of the overburden. During the middle to late Pleistocene, the diapir pierced through the extensionally thinned overburden, as indicated by rim synclines, which attest to rapid salt withdrawal from the surrounding regions. Slight positive topography above the diapir and shallow folded horizons indicate that it is still rising intermittently. The smaller Sedom diapir, exposed along the western bounding fault of the basin is presently rising and forms a 200 m-high ridge. Its initiation is explained by localized E-W extension due monoclinal draping over the edge of a rapidly subsiding basin during the early to middle Pleistocene, and its continued rise by lateral squeezing due to continued rotation of the Amazyahu diagonal fault. ?? 2001 Elsevier Science Ltd. All rights reserved.

  6. Effect of interfacial slip on the deformation of a viscoelastic drop in uniaxial extensional flow field

    NASA Astrophysics Data System (ADS)

    Das, Sayan; Mandal, Shubhadeep; Som, S. K.; Chakraborty, Suman

    2017-03-01

    The effect of interfacial slip on the deformation of a viscoelastic droplet, suspended in another viscoelastic medium, in the presence of a uniaxial extensional flow, is studied analytically. Using the Oldroyd-B constitutive relation, the Stokes flow problem is solved in the limit of a small capillary number and small Deborah number. Experimentally observed interfacial velocity slip is incorporated using a Navier slip boundary condition. The interfacial slip significantly reduces the magnitude of droplet deformation when the droplet has larger viscosity as compared with the suspending phase. The droplet shape becomes less ellipsoidal in the presence of slip. The effect of slip diminishes for low viscosity droplets. Slip effectively weakens the dependence of the droplet deformation on the droplet to medium viscosity ratio. The viscoelasticity of the suspending phase plays a dominant role on the droplet deformation as compared with the viscoelasticity of the droplet phase when there is velocity slip at the droplet surface. The interfacial slip aids the viscoelasticity of the suspending phase in deforming the droplet, while the effect of viscoelasticity of the droplet phase is suppressed by the interfacial slip.

  7. Marangoni Effects of a Drop in an Extensional Flow: The Role of Surfactant Physical Chemistry

    NASA Technical Reports Server (NTRS)

    Stebe, Kathleen J.; Balasubramaniam, R. (Technical Monitor)

    2002-01-01

    While the changes in stresses caused by surfactant adsorption on non-deforming interfaces have been fairly well established, prior to this work, there were few studies addressing how surfactants alter stresses on strongly deforming interfaces. We chose the model problem of a drop in a uniaxial extensional flow to study these stress conditions To model surfactant effects at fluid interfaces, a proper description of the dependence of the surface tension on surface concentration, the surface equation of state, is required. We have adopted a surface equation of state that accounts for the maximum coverage limit; that is, because surfactants have a finite cross sectional area, there is an upper bound to the amount of surfactant that can adsorb in a monolayer. The surface tension reduces strongly only when this maximum coverage is approached. Since the Marangoni stresses go as the derivative of the surface equation of state times the surface concentration gradient, the non-linear equation of state determines both the effect of surfactants in the normal stress jump, (which is balanced by the product of the mean curvature of the interface times the surface tension), and the tangential stress jump, which is balanced by Marangoni stresses. First, the effects of surface coverage and intermolecular interactions among surfactants which drive aggregation of surfactants in the interface were studied. (see Pawar and Stebe, Physics of Fluids).

  8. What do we learn from extensional tectonics in the Western Alps?

    NASA Astrophysics Data System (ADS)

    Sue, C.; Champagnac, J.-D.

    2009-04-01

    The Western Alps' active tectonics are characterized by ongoing widespread extension in the highest parts of the belt and transpressive/compressive tectonics along its borders (Sue et al., 1999; Delacou et al., 2004). We examine these contrasting tectonic regimes, as well as the role of erosional processes, using a multidisciplinary approach including seismotectonics, numerical modelling, GPS, morphotectonics, fieldwork, and brittle deformation analysis. Extension appears to be the dominant process in the present-day tectonic activity in the Western Alps, affecting its internal areas all along the arc. Shortening, in contrast, is limited to small areas located along at the outer borders of the chain. Strike-slip is observed throughout the Alpine realm and in the foreland. The stress-orientation pattern is radial for σ3 in the inner, extensional zones, and for σ1 in the outer, transcurrent/tranpressional ones. Extensional areas can be correlated with the parts of the belt with the thickest crust. Quantification of seismic strain in tectonically homogeneous areas shows that only 10 to 20% of the geodesy-documented deformation can be explained by the Alpine seismicity. We show that Alpine active tectonics are ruled by buoyancy forces rather than ongoing shortening along the Alpine Europe/Adria collision zone. Numerical modeling corroborates this interpretation. The Neogene extensional structures in the Alps formed under increasingly brittle conditions. A synthesis of paleostress tensors for the internal parts of the West-Alpine arc documents major orogen-parallel extension with a continuous change in σ3 directions from ENE-WSW in the Simplon area, to N-S in the Vanoise area and to NNW-SSE in the Briançon area (Champagnac et al., 2006). Minor orogen-perpendicular extension increases from N to S. This second signal correlates with present-day geodynamics as revealed by focal-plane mechanisms analysis. The orogen-parallel extension could be related to the opening of

  9. Direct observation of DNA dynamics in semidilute solutions in extensional flow

    NASA Astrophysics Data System (ADS)

    Hsiao, Kai-Wen; Sasmal, Chandi; Ravi Prakash, J.; Schroeder, Charles M.

    2017-01-01

    The dynamic behavior of semi-dilute polymer solutions is governed by an interplay between solvent quality, concentration, molecular weight, and flow type. Semi-dilute solutions are characterized by large fluctuations in concentration, wherein polymer coils interpenetrate but may not be topologically entangled at equilibrium. In non-equilibrium flows, it is generally thought that polymer chains can self-entangle in semi-dilute solutions, thereby leading to entanglements in solutions that are nominally unentangled at equilibrium. Despite recent progress, we still lack a complete molecular-level understanding of these dynamics. In this work, we use single molecule techniques to study the dynamics of semi-dilute solutions of DNA in planar extensional flow, including polymer relaxation from high stretch, transient stretching dynamics in step-strain experiments, and steady-state stretching in flow. Our results are consistent with a power-law scaling of the longest polymer relaxation time in semi-dilute solutions, revealing an effective excluded volume exponent $\

  10. Extensional fault-bend folding and synrift deposition: An example from the Central Sumatra basin, Indonesia

    SciTech Connect

    Shaw, J.H.; Hook, S.C.; Sitohang, E.P.

    1997-03-01

    We describe an analytical method for interpreting the geometry and structural history of asymmetric half grabens in rift basins with extensional fault-bend fold theory. Using seismic reflection profiles from the Central Sumatra basin and balanced forward models, we show how local variations in tectonic subsidence relative to deposition rates yield distinctive patterns of folded synrift strata and unconformities that record basin history. If the deposition rate exceeds the local subsidence rate, folded growth strata form upwardly narrowing kink bands that have been described previously as growth triangles. In contrast, if the deposition rate is less than or equals the local subsidence rate, growth strata are folded and truncated at the surface on half-graben margins. Subsequent increases in deposition rate relative to subsidence rate form angular unconformities near the half-graben margins. These unconformities develop without the necessity of erosion and are folded by continuing fault slip. Strata above and below the unconformities are concordant in the deeper parts of the half grabens. Thus, angular unconformities on half-graben margins are helpful for defining sequence boundaries that may reflect changes in deposition and tectonic subsidence rates. In addition, fault-bend fold interpretations yield fault geometry and measures of horizontal extension, both of which control three-dimensional half-graben geometry and accommodation space. We show how along-strike variations in fault geometry produce intrabasinal structures that may form prospective fair-ways or local depocenters.

  11. Nonlinear flap-lag-extensional vibrations of rotating, pretwisted, preconed beams including Coriolis effects

    NASA Technical Reports Server (NTRS)

    Subrahmanyam, K. B.; Kaza, K. R. V.

    1985-01-01

    The effects of pretwist, precone, setting angle, Coriolis forces and second degree geometric nonlinearities on the natural frequencies, steady state deflections and mode shapes of rotating, torsionally rigid, cantilevered beams were studied. The governing coupled equations of flap lag extensional motion are derived including the effects of large precone and retaining geometric nonlinearities up to second degree. The Galerkin method, with nonrotating normal modes, is used for the solution of both steady state nonlinear equations and linear perturbation equations. Parametric indicating the individual and collective effects of pretwist, precone, Coriolis forces and second degree geometric nonlinearities on the steady state deflection, natural frequencies and mode shapes of rotating blades are presented. It is indicated that the second degree geometric nonlinear terms, which vanish for zero precone, can produce frequency changes of engineering significance. Further confirmation of the validity of including those generated by MSC NASTRAN. It is indicated that the linear and nonlinear Coriolis effects must be included in analyzing thick blades. The Coriolis effects are significant on the first flatwise and the first edgewise modes.

  12. Extensional tectonic influence on lower and upper cretaceous stratigraphy and reservoirs, southern Powder River basin, Wyoming

    SciTech Connect

    Mitchell, G.C.; Rogers, M.H.

    1993-04-01

    The southern Powder River basin has been influenced significantly by an extensional system affecting Lower Cretaceous, Upper Cretaceous and Tertiary units. The system is composed of small throw, nearly vertical normal faults which are identified in the Cretaceous marine shales and that we believe are basement derived. Resultant fractures were present at erosional/depositional surfaces, both marine and nonmarine, that, in part, controlled erosion and subsequent deposition of Lower and Upper Cretaceous rocks. The normal faults also affected coal deposition in the Tertiary, now exposed at the surface. The erosion and resultant deposition formed extensive stratigraphic traps in Cretaceous units in both conventional and unconventional reservoirs. These reservoirs are interbedded with mature source rocks that have generated and expelled large amounts of hydrocarbons. Resulting overpressuring in the Fall River through the Niobrara formations has kept fractures open and has preserved primary porosity in the reservoirs. The normal faults offset thin sandstone reservoirs forming permeability barriers. Associated fractures may have provided vertical pathways for organic acids that assisted development of secondary porosity in Upper Cretaceous sandstones. These normal...faults and fractures provide significant potential for the use of horizontal drilling techniques to evaluate fractured, overpressured conventional and unconventional reservoirs.

  13. Buckling of thin viscous sheets with inhomogenous viscosity under extensional flows

    NASA Astrophysics Data System (ADS)

    Srinivasan, Siddarth; Wei, Zhiyan; Mahadevan, L.

    2016-11-01

    We investigate the dynamics, shape and stability of a thin viscous sheet subjected to an extensional flow under an imposed non-uniform temperature field. Using finite element simulations, we first solve for the stretching flow to determine the pre-buckling sheet thickness and in-plane flow velocities. Next, we use this solution as the base state and solve the linearized partial differential equation governing the out-of-plane deformation of the mid-surface as a function of two dimensionless operating parameters: the normalized stretching ratio α and a dimensionless width of the heating zone β. We show the sheet can become unstable via a buckling instability driven by the development of localized compressive stresses, and determine the global shape and growth rates of the most unstable mode. The growth rate is shown to exhibit a transition from stationary to oscillatory modes in region upstream of the heating zone. Finally, we investigate the effect of surface tension and present an operating diagram that indicates regions of the parameter space that minimizes or entirely suppresses the instability while achieving desired outlet sheet thickness. Therefore, our work is directly relevant to various industrial processes including the glass redraw & float-glass method.

  14. Rotation of late Cenozoic extensional stresses, Yucca Flat region, Nevada Test Site, Nevada

    SciTech Connect

    Ander, H.D.

    1984-12-31

    The Nevada Test Site (NTS) is located in the southern Basin and Range where the geology is typified by complexly deformed Paleozoic sedimentary rocks underlying Tertiary and Quaternary volcanics and alluvium all displaced by Cenozoic normal faults. The purpose of this study is to interpret the history of change in Cenozoic extensional stress orientations using ash-flow distributions, surface fault configurations, and slickenside analyses. Extensive drill hole data collected from Yucca Flat within NTS were used to construct isopach and structure contour maps of Cenozoic units occupying the northerly-trending basin. The configuration of these units indicates that the north-south-trending faults controlling present day basin morphology were inactive during deposition of the volcanic rocks from approximately 25 to 11 myBP. However, after 11 myBP, the overlying sedimentary sequence was strongly influenced by these faults and consequent basin development. In particular, an inordinately thick section of late Tertiary and Quaternary alluvium occurs at the southwestern end of Yucca Flat. Southwest-striking faults at the southwestern and of Yucca flat are postulated to be deflected at their northeast ends, becoming continuous with the north-south basin forming fault sets.

  15. Probable Middle Cambrian and Middle-Late Ordovician seismites, a record of extensional to compressional tectonics

    SciTech Connect

    Pope, M.C.; Read, J.F. . Dept. of Geology)

    1992-01-01

    Facies resembling seismites, in situ shock deformation of sediments related to earthquake activity, appear to be developed in a Middle Cambrian intrashelf basinal setting in Virginia, and in a Middle-Late Ordovician foreland basin setting throughout Virginia and Kentucky. The Middle Cambrian facies developed during Rome trough and Conasauga basin extensional tectonics, whereas the Middle and Late Ordovician examples developed during eastward subduction of the North American plate (Taconic Orogeny). The seismites are characterized by contorted bedding, abundant ball and pillow structures, upward injection of sediment, in-place foundering of large blocks with erosional tops, development of mud-supported chaotic conglomerate fabrics and perhaps compacted sediment filled dikes in shale. The seismites occur in both clastic and carbonate, fine-to-carose grained sediments and vary in scale from centimeters to meters. The contorted bedding probably relates to seismically induced liquefaction of sediments within the upper few meters of section, whereas ball and pillow formation and sediment injection is due to water escape. The low sedimentation rates in the intrashelf basin and on the foreland ramp would tend to preclude these features resulting from high sedimentation rates causing loading of water-rich mud sections, even though some beds related to storm deposition. In fact, most of the storm beds, even thicker ones, show little evidence of ball and pillow formation. Seismites may provide an important temporal record of earthquakes affecting these basins, and need to be recognized if one is to separate tectonic from eustatic effects in these basins.

  16. Extensional deformation structures within a convergent orogen: The Val di Lima low-angle normal fault system (Northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Clemenzi, Luca; Molli, Giancarlo; Storti, Fabrizio; Muchez, Philippe; Swennen, Rudy; Torelli, Luigi

    2014-09-01

    A low-angle extensional fault system affecting the non metamorphic rocks of the carbonate dominated Tuscan succession is exposed in the Lima valley (Northern Apennines, Italy). This fault system affects the right-side-up limb of a kilometric-scale recumbent isoclinal anticline and is, in turn, affected by superimposed folding and late-tectonic high-angle extensional faulting. The architecture of the low-angle fault system has been investigated through detailed structural mapping and damage zone characterization. Pressure-depth conditions and paleofluid evolution of the fault system have been studied through microstructural, mineralogical, petrographic, fluid inclusion and stable isotope analyses. Our results show that the low-angle fault system was active during exhumation of the Tuscan succession at about 180°C and 5 km depth, with the involvement of low-salinity fluids. Within this temperature - depth framework, the fault zone architecture shows important differences related to the different lithologies involved in the fault system and to the role played by the fluids during deformation. In places, footwall overpressuring influenced active deformation mechanisms and favored shear strain localization. Our observations indicate that extensional structures affected the central sector of the Northern Apennines thrust wedge during the orogenic contractional history, modifying the fluid circulation through the upper crust and influencing its mechanical behavior.

  17. Extensional salt tectonics in the partially inverted Cotiella post-rift basin (south-central Pyrenees): structure and evolution

    NASA Astrophysics Data System (ADS)

    López-Mir, Berta; Muñoz, Josep Anton; García-Senz, Jesús

    2015-03-01

    The Cotiella Massif in the south-central Pyrenees hosts upper Cretaceous gravity-driven extensional faults which were developed in the Bay of Biscay-Pyrenean paleorift margin of the Atlantic Ocean. They accommodate up to 6 km of post-rift carbonates above relict upper Triassic salt. Subsequent Pyrenean contractional deformation preserved the main extensional features, but most of the upper Triassic salt was expulsed and then dissolved, leaving little indications of the original salt volume. Nonetheless, several distinctive salt-related features are still recognizable both at outcrop and at basin scale, providing an exposed analogue for salt-floored extensional basins developed on passive margins. Based on field research, we re-interpret the tectonic evolution of the area and suggest that passive diapirs were coeval with gravity-driven extension during the development of the Cotiella basin. The given interpretations are supported with detailed geological maps, original structural data, cross sections and outcrop photographs. The discovery of previously unknown post-rift salt structures in the Cotiella Massif is an extra element to consider in the paleogeographic reconstructions of the upper Cretaceous passive margin of the Bay of Biscay-Pyrenean realm and consequently helps in our understanding of the evolution of current Atlantic-type margins.

  18. The rift architecture and extensional tectonics of the South China Sea

    NASA Astrophysics Data System (ADS)

    Cameselle, Alejandra L.; Ranero, César R.; Barckhausen, Udo; Franke, Dieter

    2016-04-01

    Non-volcanic rifted continental margins are classically described as the product of lithospheric stretching and breakup leading to mantle exhumation, and subsequent seafloor spreading. However, recent studies question this model and indicate a wider range of structural evolutions, that challenge the existing model (e.g. Australia-Antarctic Rift System (Direen et al. 2007, 2011); the Tyrrhenian basin (Prada et al., 2014) or the South China Sea (Cameselle et al. 2015)). Rifting in the South China Sea developed from a series of extensional events, from early Eocene to Late Oligocene, resulting in a V-shape oceanic basin affected by the occurrence of several spreading centers, ridges, transform faults and post-spreading volcanism. In recent years, this marginal basin - the largest in East Asia - has increasingly become one of the key sites for the study of rifting and continental break-up. Its relative small size - compared to many classic, Atlantic-type continental margin settings - allows to easily match conjugated rifted margins and its relative youth promotes the preservation of its original nature. To examine the rifting evolution of the South China Sea, we have reprocessed with modern algorithms multichannel seismic profiles acquired during Sonne49 and BGR84 cruises across the three major subbasins: NW, SW and East subbasins. State-of-the-art of processing techniques have been used to increase the signal to noise ratio, including Tau-P and Wiener predictive deconvolution, multiple attenuation by both radon filtering and wave-equation-based surface-related multiple elimination (SRME) and time migration. To complement seismic interpretation, available vintage multichannel seismic data have been reprocessed with a post-stack flow, including Wiener deconvolution, FK-filtering, space and time variant band-pass filter and time migration. The improving quality of the seismic images shows a range of features including post-rift and syn-rift sediments, the structure of

  19. P-T data from central Bhutan imply distributed extensional shear at the Black Mountain "klippe"

    NASA Astrophysics Data System (ADS)

    Corrie, S. L.; Kohn, M. J.; Long, S. P.; McQuarrie, N.; Tobgay, T.

    2011-12-01

    The Southern Tibetan Detachment system (STDS) occurs along the entire length of the Himalayan orogen, and extensionally emplaces low-grade to unmetamorphosed Tethyan Himalayan (TH) rocks over highly metamorphosed Greater Himalayan sequence (GH) rocks. The base of TH remnants preserved in northern Bhutan all have top-to-the-north shear sense indicators (C'-type shear bands, asymmetric folds, and boudinaged leucogranite dikes) that are interpreted to reflect a discrete shear zone. In contrast, the GH-TH contact in the southernmost TH remnant (the Black Mountain region, central Bhutan) has been interpreted as depositional. A depositional contact limits the magnitude of displacement along the early STDS to 10's of km. If the GH-TH contact in the Black Mountain region is instead a discrete shear zone, as observed farther north, displacement on the STDS could be as high as 100's of km. To discriminate between these two interpretations, we determined peak metamorphic P-T conditions through the GH and TH sections, reasoning that a discrete shear zone would produce a distinct jump in metamorphic temperature, pressure or both. Thin section-scale kinematic indicators reveal pervasive top-to-the-north shear from 2-3 km structurally above the Main Central thrust (MCT) through the rest of the 11 km thick GH and TH sections. P-T conditions were determined from immediately above the MCT to 4 km above the GH-TH contact, with 19 samples from the GH, 6 from the overlying Chekha Fm (TH), and 9 from the overlying Maneting Fm (TH). We applied standard Fe-Mg exchange thermometers and Ca net-transfer barometers involving garnet. P-T conditions range from 700 °C and 11 kbar in migmatitic GHS to 600 °C and 8 kbar at the GH-Chekha contact, and 500 °C and 5 kbar at the top of the Maneting. We found no jumps in either temperature or pressure at any level, but a steeper than lithostatic pressure gradient, which we interpret to result from distributed extensional shear. The average thermal

  20. Carbon fluxes from hydrothermal vents off Milos, Aegean Volcanic Arc, and the influence of venting on the surrounding ecosystem.

    NASA Astrophysics Data System (ADS)

    Dando, Paul; Aliani, Stefano; Bianchi, Nike; Kennedy, Hilary; Linke, Peter; Morri, Carla

    2014-05-01

    The island of Milos, in the Aegean Sea, has extensive hydrothermal fields to the east and southeast of the island with additional venting areas near the entrance to and within the central caldera. A calculation of the total area of the vent fields, based on ship and aerial surveys, suggested that the hydrothermal fields occupy 70 km2, twice the area previously estimated. The vents ranged in water depth from the intertidal to 300 m. As a result of the low depths there was abundant free gas release: in places water boiled on the seabed. The stream of gas bubbles rising through the sandy seabed drove a shallow re-circulation of bottom seawater. The majority of the water released with the gas, with a mean pH of 5.5, was re-circulated bottom water that had become acidified in contact with CO2 gas and was often diluted by admixture with the vapour phase from the deeper fluids. The major component of the free gas, 80%, was CO2, with an estimated total flux of 1.5-7.5 x 1012 g a-1. The methane flux, by comparison, was of the order of 1010 g a.-1 Using methane as a tracer it was shown that the major gas export from the vents was below the thermocline towards the southwest, in agreement with the prevailing currents. Areas of hydrothermal brine seepage occurred between the gas vents and occasional brine pools were observed in seabed depressions. Under relatively calm conditions, many of the brine seeps were covered by thick minero-bacterial mats consisting of silica and sulphur and surrounded by mats of diatoms and cyanobacteria. The minerals were not deposited in the absence of bacteria. Storms disrupted the mats, leading to an export of material to the surrounding area. Stable isotope data from sediments and sediment trap material suggested that exported POM was processed by zooplankton. The combined effects of the geothermal heating of the seabed, the large gas flux, variation in the venting and the effect of the brine seeps had a dramatic effect on the surrounding

  1. Tectonic and gravity extensional collapses in overpressured cohesive and frictional wedges

    NASA Astrophysics Data System (ADS)

    Yuan, X. P.; Leroy, Y. M.; Maillot, B.

    2015-03-01

    Two modes of extensional collapse in a cohesive and frictional wedge of arbitrary topography, finite extent, and resting on an inclined weak décollement are examined by analytical means. The first mode consists of the gravitational collapse by the action of a half-graben, rooting on the décollement and pushing seaward the frontal part of the wedge. The second mode results from the tectonics extension at the back wall with a similar half-graben kinematics and the landward sliding of the rear part of the wedge. The predictions of the maximum strength theorem, equivalent to the kinematic approach of limit analysis and based on these two collapse mechanisms, not only match exactly the solutions of the critical Coulomb wedge theory, once properly amended, but generalizes them in several aspects: wedge of finite size, composed of cohesive material and of arbitrary topography. This generalization is advantageous to progress in our understanding of many laboratory experiments and field cases. For example, it is claimed from analytical results validated by experiments that the stability transition for a cohesive, triangular wedge occurs with the activation of the maximum length of the décollement. It is shown that the details of the topography, for the particular example of the Mejillones peninsula (North Chile) is, however, responsible for the selection of a short length-scale, dynamic instability corresponding to a frontal gravitational instability. A reasonable amount of cohesion is sufficient for the pressures proposed in the literature to correspond to a stability transition and not with a dynamically unstable state.

  2. Experimental characterization of breakage rate of colloidal aggregates in axisymmetric extensional flow.

    PubMed

    Saha, Debashish; Soos, Miroslav; Lüthi, Beat; Holzner, Markus; Liberzon, Alex; Babler, Matthaus U; Kinzelbach, Wolfgang

    2014-12-09

    Aggregates prepared under fully destabilized conditions by the action of Brownian motion were exposed to an extensional flow generated at the entrance of a sudden contraction. Two noninvasive techniques were used to monitor their breakup process [i.e. light scattering and three-dimensional (3D) particle tracking velocimetry (3D-PTV)]. While the first one can be used to measure the size and the morphology of formed fragments after the breakage event, the latter is capable of resolving trajectories of individual aggregates up to the breakage point as well as the trajectories of formed fragments. Furthermore, measured velocity gradients were used to determine the local hydrodynamic conditions at the breakage point. All this information was combined to experimentally determine for the first time the breakage rate of individual aggregates, given in the form of a size reduction rate K(R), as a function of the applied strain rate, as well as the properties of the formed fragments (i.e., the number of formed fragments and the size ratio between the largest fragment and the original aggregate). It was found that K(R) scales with the applied strain rate according to a power law with the slope being dependent on the initial fractal dimension only, while the obtained data indicates a linear dependency of K(R) with the initial aggregate size. Furthermore, the probability distribution function (PDF) of the number of formed fragments and the PDF of the size ratio between the largest fragment and the original aggregate indicate that breakage will result with high probability (75%) in the formation of two to three fragments with a rather asymmetric ratio of sizes of about 0.8. The obtained results are well in agreement with the results from the numerical simulations published in the literature.

  3. Testing fault displacement-length scaling relations through analogue modeling in an extensional setting

    NASA Astrophysics Data System (ADS)

    Bonini, L.; Basili, R.; Burrato, P.; Kastelic, V.; Toscani, G.; Seno, S.; Valensise, G.

    2013-12-01

    The scaling relation between displacement and length of faults plays a crucial role in understanding the growth history of individual faults and their possible linkage and reactivation in future ruptures. Displacement-length relations are commonly based on empirical data. The measurement of fault geometric properties, however, is generally affected by large scattering due not only to intrinsic difficulties of making observations in natural cases (outcrop availability, seismic profiles), but also to the variety of geological factors that may affect the rupture patterns. These can be the interaction between the present-day tectonic regime and an inherited structural fabric, or that between a master fault at depth and shallow structural features. As an alternative to field observations, analogue modeling provides an opportunity to investigate the faulting processes in a controlled environment. During the last decade, the ability of scaled models to properly reproduce such geological processes has greatly improved thanks to the introduction of new materials (e.g. wet kaolin) suitable for reproducing brittle deformation in the upper crust and hi-tech monitoring systems (e.g. laser scanner, particle image velocimetry) with the ability of capturing structural details and performing accurate measurements. We use a dedicated apparatus with such properties to gain insights on the evolution of extensional faults through a suite of experiments which includes (a) setups in homogeneous material to test our ability in meeting general criteria related with fault displacement-length parameters; and (b) increasing complexities attained by inserting various pre-existing fault patterns to analyze how shallow mechanical discontinuities affect our ability to characterize a major fault at depth. Our results show that pre-existing faults can either halt or favor fault development and growth depending on their location/orientation with respect to the applied stress field and suggest the

  4. The effect of bimineralic composition on extensional processes at lithospheric scale

    NASA Astrophysics Data System (ADS)

    Jammes, S.; Lavier, L. L.

    2015-12-01

    In a bimineralic material the deformation localization is strongly dependent on the mechanical behavior of the two phases, the proportion, and the strength contrast between them. If these parameters vary at the scale of a rock sample, they also vary at lithospheric scale when units with different lithologies are juxtaposed leading to the strongly heterogeneous crust and mantle. In the lithosphere, moreover, the dependence with depth of the pressure-temperature imposes that the strength ratio between the different phases is also dependent on the depth and geotherm. Based on our previous result, we expect therefore that the compositional heterogeneities strongly influence the localization and that the resulting complex mechanisms of deformation are dependent of the geotherm and proportion of different materials constituting the lithosphere. To test these ideas, we perform lithospheric scale models with a bimineralic composition in the crust and the mantle to take into account the compositional heterogeneities. We deform the model in an extensional setting and systematically change the Moho temperature and the composition of the crust and mantle.. Comparison of our models to simulations using a monomineralic crust and mantle demonstrates that a bimineralic composition assimilated to heterogeneities succeed in explaining observations related to the formation of rifted margins such as : 1) the absence of a sharp brittle ductile transition,2) the initiation of the rifting process as a wide delocalized rift system where multiple normal faults dipping in both directions; 3) the development of an anastomosing shear zone in the middle/lower crust and the upper lithospheric mantle similar to the crustal scale anastomosing pattern observed on the field or in seismic data; 4) the preservation of undeformed lenses of material leading to lithospheric scale boudinage structure and resulting in the formation of continental ribbons as observed along the Iberian-Newfoundland margin.

  5. Single-molecule sequence detection via microfluidic planar extensional flow at a stagnation point.

    PubMed

    Dylla-Spears, Rebecca; Townsend, Jacqueline E; Jen-Jacobson, Linda; Sohn, Lydia L; Muller, Susan J

    2010-06-21

    We demonstrate the use of a microfluidic stagnation point flow to trap and extend single molecules of double-stranded (ds) genomic DNA for detection of target sequences along the DNA backbone. Mutant EcoRI-based fluorescent markers are bound sequence-specifically to fluorescently labeled ds lambda-DNA. The marker-DNA complexes are introduced into a microfluidic cross slot consisting of flow channels that intersect at ninety degrees. Buffered solution containing the marker-DNA complexes flows in one channel of the cross slot, pure buffer flows in the opposing channel at the same flow rate, and fluid exits the two channels at ninety degrees from the inlet channels. This creates a stagnation point at the center of a planar extensional flow, where marker-DNA complexes may be trapped and elongated along the outflow axis. The degree of elongation can be controlled using the flow strength (i.e., a non-dimensional flow rate) in the device. Both the DNA backbone and the markers bound along the stretched DNA are observed directly using fluorescence microscopy, and the location of the markers along the DNA backbone is measured. We find that our method permits detection of each of the five expected target site positions to within 1.5 kb with standard deviations of <1.5 kb. We compare the method's precision and accuracy at molecular extensions of 68% and 88% of the contour length to binding distributions from similar data obtained via molecular combing. We also provide evidence that increased mixing of the sample during binding of the marker to the DNA improves binding to internal target sequences of dsDNA, presumably by extending the DNA and making the internal binding sites more accessible.

  6. Theory and Simulation of Extensional Flow-Induced Biaxiality in Discotic Mesophases

    NASA Astrophysics Data System (ADS)

    Singh, Arvinder P.; Rey, Alejandro D.

    1995-09-01

    Flow-induced biaxiality is simulated for a uniaxial discotic nematic liquid crystal subjected to a constant uniaxial, isothermal, incompressible, irrotational, extensional, three dimensional flow, using a previously presented model [Singh A.P. and Rey A.D., J. Phys. II France 4 (1994) 645]. Numerical and analytical solutions of the director triad (n, m, l), and uniaxial (S) and biaxial (P) alignments are given. The unit sphere description of the director triad is used to discuss and analyze the sensitivity of the director triad trajectories and the coupled alignment (uniaxial and biaxial) relaxations to the initial orientation, nematic potential (U), and to the alignment Deborah number (dimensionless extension rate). The evolution of the director triad is given by the rotation of a moving diad (n, l) around a fixed director (m). When the poles of the orientation unit sphere are along the extension axis, and the equator lies in the compression plane of the flow, it is found that the director diad (n, l) dynamics follow geodesic flow and the trajectories belong to the same meridians (great circles through the poles). The space of stable steady state orientation of the uniaxial director n and the biaxial director m is the whole compression plane (the equator of the unit sphere), while that of the biaxial director l is the extension direction (poles). A high degree extension flow-induced biaxiality is found when the uniaxial director is away from the extension axis and when S is relatively low. The scalar order parameter couplings are captured by analyzing the trajectories in the alignment triangle. Computed scientific visualizations of biaxial molecular orientation distributions are used to correlate the director triad dynamics and the alignment's dynamics. The tensor order parameter is used to calculate the main flow-birefringences, thus providing a direct way to verify the theoretical predictions of this paper.

  7. Hydrothermal dolomitization of basinal deposits controlled by a synsedimentary fault system in Triassic extensional setting, Hungary

    NASA Astrophysics Data System (ADS)

    Hips, Kinga; Haas, János; Győri, Orsolya

    2016-06-01

    Dolomitization of relatively thick carbonate successions occurs via an effective fluid circulation mechanism, since the replacement process requires a large amount of Mg-rich fluid interacting with the CaCO3 precursor. In the western end of the Neotethys, fault-controlled extensional basins developed during the Late Triassic spreading stage. In the Buda Hills and Danube-East blocks, distinct parts of silica and organic matter-rich slope and basinal deposits are dolomitized. Petrographic, geochemical, and fluid inclusion data distinguished two dolomite types: (1) finely to medium crystalline and (2) medium to coarsely crystalline. They commonly co-occur and show a gradual transition. Both exhibit breccia fabric under microscope. Dolomite texture reveals that the breccia fabric is not inherited from the precursor carbonates but was formed during the dolomitization process and under the influence of repeated seismic shocks. Dolomitization within the slope and basinal succession as well as within the breccia zones of the underlying basement block is interpreted as being related to fluid originated from the detachment zone and channelled along synsedimentary normal faults. The proposed conceptual model of dolomitization suggests that pervasive dolomitization occurred not only within and near the fault zones. Permeable beds have channelled the fluid towards the basin centre where the fluid was capable of partial dolomitization. The fluid inclusion data, compared with vitrinite reflectance and maturation data of organic matter, suggest that the ascending fluid was likely hydrothermal which cooled down via mixing with marine-derived pore fluid. Thermal gradient is considered as a potential driving force for fluid flow.

  8. Comparative phylogeography of tenebrionid beetles in the Aegean archipelago: the effect of dispersal ability and habitat preference.

    PubMed

    Papadopoulou, Anna; Anastasiou, Ioannis; Keskin, Bekir; Vogler, Alfried P

    2009-06-01

    Comparative phylogeographical studies in island archipelagos can reveal lineage-specific differential responses to the geological and climatic history. We analysed patterns of genetic diversity in six codistributed lineages of darkling beetles (Tenebrionidae) in the central Aegean archipelago which differ in wing development and habitat preferences. A total of 600 specimens from 30 islands and eight adjacent mainland regions were sequenced for mitochondrial cytochrome oxidase I and nuclear Muscular protein 20. Individual gene genealogies were assessed for the presence of groups that obey an independent coalescent process using a mixed Yule coalescent model. The six focal taxa differed greatly in the number of coalescent groups and depth of lineage subdivision, which was closely mirrored by the degree of geographical structuring. The most severe subdivision at both mitochondrial DNA and nuclear DNA level was found in flightless lineages associated with presumed stable compact-soil habitats (phrygana, maquis), in contrast to sand-obligate lineages inhabiting ephemeral coastal areas that displayed greater homogeneity across the archipelago. A winged lineage, although associated with stable habitats, showed no significant phylogenetic or geographical structuring. Patterns of nucleotide diversity and local genetic differentiation, as measured using PhiST and hierarchical AMOVA, were consistent with high levels of ongoing gene flow in the winged taxon; frequent local extinction and island recolonisation for flightless sand-obligate taxa; and very low gene flow and geographical structure largely defined by the palaeogeographical history of the region in flightless compact-soil taxa. These results show that differences in dispersal rate, mediated by habitat persistence, greatly influence the levels of phylogeographical subdivision in lineages that are otherwise subjected to the same geological events and palaeoclimatic changes.

  9. Hydrodynamic features of the South Aegean Sea as derived from Argo T/ S and dissolved oxygen profiles in the area

    NASA Astrophysics Data System (ADS)

    Kassis, Dimitris; Krasakopoulou, Evangelia; Korres, Gerasimos; Petihakis, George; Triantafyllou, George S.

    2016-11-01

    In this work, the hydrodynamic picture of the South Aegean Sea is examined through an analysis of recent measurements in its sub-basins, the Myrtoan and Cretan Sea. Both sub-basins play an important role in the water circulation, exchange, and formation processes that affect the dynamics of the whole Eastern Mediterranean. For the first time, Bio-Argo floats were deployed in the area under the Greek Argo Research Infrastructure coordination. The acquired profiles cover an almost 2-year period (November 2013-July 2015) and are compared with previous Argo profiles and the re-processed time-series data recorded from the E1-M3A POSEIDON observatory operating in the area since 2007. The spatio-temporal distribution of the physical and chemical properties in each sub-basin is examined. Dense water formation events are revealed in the northern part (Myrtoan), while the wider area can be characterized as pre-conditioned. In the Cretan basin, a strong inter-annual variability of the salinity field at intermediate and deep layers is observed that is associated with water exchange from its open boundaries. Furthermore, comparison of the dissolved oxygen (DO) distribution with physical water properties within both the mixed layer, and at greater depths, indicated that relatively high but still under-saturated DO values are more likely to be associated with convection events. Finally, an updated picture of the physical properties and the DO distribution is presented based on the last 5 years of measurements and the recent introduction of Bio-Argo floats with DO sensors in the area.

  10. Source of the tsunami generated by the 1650 AD eruption of Kolumbo submarine volcano (Aegean Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Ulvrova, Martina; Paris, R.; Nomikou, P.; Kelfoun, K.; Leibrandt, S.; Tappin, D. R.; McCoy, F. W.

    2016-07-01

    The 1650 AD explosive eruption of Kolumbo submarine volcano (Aegean Sea, Greece) generated a destructive tsunami. In this paper we propose a source mechanism of this poorly documented tsunami using both geological investigations and numerical simulations. Sedimentary evidence of the 1650 AD tsunami was found along the coast of Santorini Island at maximum altitudes ranging between 3.5 m a.s.l. (Perissa, southern coast) and 20 m a.s.l. (Monolithos, eastern coast), corresponding to a minimum inundation of 360 and 630 m respectively. Tsunami deposits consist of an irregular 5 to 30 cm thick layer of dark grey sand that overlies pumiceous deposits erupted during the Minoan eruption and are found at depths of 30-50 cm below the surface. Composition of the tsunami sand is similar to the composition of the present-day beach sand but differs from the pumiceous gravelly deposits on which it rests. The spatial distribution of the tsunami deposits was compared to available historical records and to the results of numerical simulations of tsunami inundation. Different source mechanisms were tested: earthquakes, underwater explosions, caldera collapse, and pyroclastic flows. The most probable source of the 1650 AD Kolumbo tsunami is a 250 m high water surface displacement generated by underwater explosion with an energy of 2 × 1016 J at water depths between 20 and 150 m. The tsunamigenic explosion(s) occurred on September 29, 1650 during the transition between submarine and subaerial phases of the eruption. Caldera subsidence is not an efficient tsunami source mechanism as short (and probably unrealistic) collapse durations (< 5 min) are needed. Pyroclastic flows cannot be discarded, but the required flux (106 to 107 m3 · s- 1) is exceptionally high compared to the magnitude of the eruption.

  11. Source of the tsunami generated by the 1650 AD eruption of Kolumbo submarine volcano (Aegean Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Ulvrova, Martina; Paris, Raphael; Nomikou, Paraskevi; Tappin, Dave

    2016-04-01

    The 1650 AD explosive eruption of Kolumbo submarine volcano (Aegean Sea, Greece) generated a destructive tsunami. In this paper we propose a source mechanism of this poorly documented tsunami using both geological investigations and numerical simulations. Sedimentary evidences of the 1650 AD tsunami were found along the coast of Santorini Island at maximum altitudes ranging between 3.5 m a.s.l. (Perissa, southern coast) and 20 m a.s.l. (Monolithos, eastern coast), corresponding to a minimum inundation of 360 and 630 m respectively. Tsunami deposits correspond to an irregular 5 to 30 cm thick layer of dark grey sand intercalated in soil at depths between 30 and 50 cm. Composition of the tsunami sand is similar to the composition of the present-day beach and clearly differs from the pumiceous gravelly soil. Spatial distribution of the tsunami deposits was confronted to available historical records and to the results of numerical simulations of tsunami inundation. Different scenarios of source mechanism were tested: earthquakes, underwater explosions, caldera collapse, and pyroclastic flows. The most probable source of the 1650 AD Kolumbo tsunami is a 250 m high water surface displacement generated by underwater explosion with an energy of ~2 E15 J at water depths between 20 and 150 m. The tsunamigenic explosion(s) occurred on September 29, 1650 during the transition between submarine and subaerial phases. Caldera subsidence is not an efficient source of tsunami, as short (and probably unrealistic) collapse durations (< 5 minutes) are needed. Pyroclastic flows cannot be discarded, but the required flux (E6 to E7 m³.s-1) is exceptionally high compared to the magnitude of the eruption.

  12. Tracing metal pollution sources of plants and soils in Güzelhisar Basin of Aegean Region, Turkey

    NASA Astrophysics Data System (ADS)

    Czarnecki, Sezin; Görsch, Carolin; Colak Esetlili, Bihter; Esetlili, Tolga; Tepecik, Mahmut; Kurucu, Yusuf; Anac, Dilek; Düring, Rolf-Alexander

    2016-04-01

    The study area Güzelhisar Basin is 6 km far from the city Aliaga, Aegean Region in the west part of Turkey which represents a rather industrialized area having five large iron and steel mills, but also areas of agriculture. A grid system of 2.5 km to the east and 2.5 km to the west of the Güzelhisar Stream was studied. The area was grouped into three main areas as West, Middle, and East region. Every 500 meters soil samples were taken after the rainfall (April-May) in 2014 from the GPS determined points at 0-30 and 30-60 cm depth. Soil reaction of the study area was determined within the range from 5.87 to 6.61. Even though, the West and the Middle regions had weak carbonate concentrations, the East region was poor in carbonates and relatively high electrical conductivity was measured. Topsoil contamination was examined by all investigated elements with the exception of Cd. An increase in pseudo total metal contents of Cr, Cu, Mn, Ni, and Zn was observed with the increasing distance from the coast with a simultaneous decrease in pH. Moreover, high plant metal concentrations [mg kg-¹, ± sd] were detected for B [20.7 ± 23.9], Cu [7.99 ± 5.17], Mn (79.3 ± 89.2), Ni (3.50 ± 3.48), and Zn (25.5 ± 20.1). Transfer of the elements from soil to plants increased in the following order: Co < As < Cr < Pb < Mn < Ni < Cu < Zn < Cd << B.

  13. Radiometric dating of sediment cores from a hydrothermal vent zone off Milos Island in the Aegean Sea.

    PubMed

    Ugur, Aysun; Miquel, Juan-Carlos; Fowler, Scott W; Appleby, Peter

    2003-05-20

    Sediment cores from a hydrothermal vent zone off Milos Island in the Aegean Sea were dated using the 210Pb method. The average unsupported 210Pb inventory in the cores was calculated to be 3256 Bq m(-2). The corresponding mean annual 210Pb flux of 105 Bq m(-2) year(-1) is comparable to estimates of the atmospheric flux given in the literature. 210Pb fluxes calculated from the unsupported 210Pb inventories in cores are also comparable with the 210Pb vertical fluxes determined from settling particles off the coast of Milos Island. The highest unsupported 210Pb concentrations (89 Bq kg(-1)) were measured in the sediments nearest to the hydrothermal vent area suggesting that the sedimentation rate is lowest at this site. Direct gamma measurements of 210Pb were used to date three sediment cores that are located at different distances from the vent zone: one is in the immediate vicinity of the vent; and others are outside the zone. Sedimentation rates for these cores, calculated using the CRS and CIC models, ranged from 0.088+/-0.008 cm year(-1) to 0.14+/-0.01 cm year(-1). Where both models were applicable, the results given by the two methods were in good agreement. 137Cs concentrations in all three cores generally declined with depth but showed no clear signal of either the period of maximum fallout from weapons testing or the Chernobyl accident. 210Po activities were also measured and the maximum 210Po concentration was in the sediment surface layer (166 Bq kg(-1)).

  14. New particle formation in the southern Aegean Sea during the Etesians: importance for CCN production and cloud droplet number

    NASA Astrophysics Data System (ADS)

    Kalkavouras, Panayiotis; Bossioli, Elissavet; Bezantakos, Spiros; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Kouvarakis, Giorgos; Protonotariou, Anna P.; Dandou, Aggeliki; Biskos, George; Mihalopoulos, Nikolaos; Nenes, Athanasios; Tombrou, Maria

    2017-01-01

    This study examines how new particle formation (NPF) in the eastern Mediterranean in summer affects CCN (cloud condensation nuclei) concentrations and cloud droplet formation. For this, the concentration and size distribution of submicron aerosol particles, along with the concentration of trace gases and meteorological variables, were studied over the central (Santorini) and southern Aegean Sea (Finokalia, Crete) from 15 to 28 July 2013, a period that includes Etesian events and moderate northern surface winds. Particle nucleation bursts were recorded during the Etesian flow at both stations, with those observed at Santorini reaching up to 1.5 × 104 particles cm-3; the fraction of nucleation-mode particles over Crete was relatively diminished, but a higher number of Aitken-mode particles were observed as a result of aging. Aerosol and photochemical pollutants covaried throughout the measurement period; lower concentrations were observed during the period of Etesian flow (e.g., 43-70 ppbv for ozone and 1.5-5.7 µg m-3 for sulfate) but were substantially enhanced during the period of moderate surface winds (i.e., increase of up to 32 for ozone and 140 % for sulfate). We find that NPF can double CCN number (at 0.1 % supersaturation), but the resulting strong competition for water vapor in cloudy updrafts decreases maximum supersaturation by 14 % and augments the potential droplet number only by 12 %. Therefore, although NPF events may strongly elevate CCN numbers, the relative impacts on cloud droplet number (compared to pre-event levels) is eventually limited by water vapor availability and depends on the prevailing cloud formation dynamics and the aerosol levels associated with the background of the region.

  15. Ductile nappe stacking and refolding in the Cycladic Blueschist Unit: insights from Sifnos Island (south Aegean Sea)

    NASA Astrophysics Data System (ADS)

    Aravadinou, Eirini; Xypolias, Paraskevas; Chatzaras, Vasileios; Iliopoulos, Ioannis; Gerogiannis, Nikolaos

    2016-10-01

    New geological and structural mapping combined with kinematic and amphibole chemistry analyses is used to investigate the deformation history of the Cycladic Blueschist Unit (CBU) on Sifnos Island (Cyclades, Aegean Sea). We concentrate on north Sifnos, an area characterized by exceptionally well-preserved eclogites and blueschists. Our data show that the early, main phase (D2) of ductile deformation in the CBU occurred synchronous with the transition from prograde to close-to-peak retrograde conditions. This deformation phase took place at middle Eocene and is related to ESE-directed thrusting that emplaced the metavolcano-sedimentary subunit over the Marble subunit. The subsequent exhumation-related (D3) deformation is characterized by gently NE-plunging folds and NE-directed contractional shear zones that formed parallel to the axial planes of folds. NE-directed shearing occurred under blueschist and transitional blueschist-/greenschist-facies conditions during late Eocene-Oligocene and caused the restacking of the early nappe pile. We suggest that a mechanism of ductile extrusion of the CBU in a tectonic setting of net compression could explain better the recorded exhumation-related deformation than a mechanism of syn- and post-orogenic extension. Our new kinematic results in combination with previous works in the Cyclades area reveal a regional scale change in tectonic transport direction from (W)NW-(E)SE at Late Cretaceous-middle Eocene to (E)NE-(W)SW at late Eocene-Oligocene times. The observed change in transport direction may be governed by the relative motion of Africa with respect to Europe during Alpine orogeny.

  16. Seismotectonic analysis of the Lunigiana and Garfagnana extensional basins (Northern Tuscany, Italy)

    NASA Astrophysics Data System (ADS)

    Brozzetti, F.; Boncio, P.; di Naccio, D.; Lavecchia, G.; Torelli, L.; Eva, E.; Solarino, S.

    2009-04-01

    We investigated the active and potentially seismogenic sources of the Lunigiana and Garfagnana extensional basins by integrating geological and morpho-structural surveys with seismological and seismic reflection data. The Lunigiana and Garfagnana basins are NW-SE grabens, originated in the hanging wall of a E-NE dipping low-angle detachment faults outcropping in the northern Tuscany Apennines. The conjugate faults bounding the basins join with the detachment at depths varying from 1 to 2.5 sec TWT, from W to E. The outcrop expression of the two fault sets is similar but the east-dipping faults show, on average, lower dip-angles (i) (30°4 km) than the west-dipping ones (50°extensional stress field characterized by a NE-SW-trending sigma3 axis. In the Lunigiana, the depth geometry of the detachment and of the main high-angle faults has been accurately defined by interpreting three seismic lines down to the depths of 4.5-5 sec TWT (~12-15 km). The east-dipping Mulazzo and Olivola faults and the west-dipping Groppodalosio and Compione faults show the strongest geomorphic signature and are the most likely active faults. This is also confirmed by the geomorphic analysis carried out integrating aerial photograph interpretation and medium resolution DTM analysis. In the Garfagnana, the NW-SE striking Casciana-Sillicano and Bolognana-Gioviano east-dipping faults show morpho-structural evidence of Late Quaternary movements and can be interpreted as active and potentially seismogenic structures. Along the eastern side, the major antithetical Quaternary faults crop out along the M. Prato- M. Mosca ridge. The geometry of the active faults has been compared with the distribution of seismicity. Our instrumental dataset consists of about 500 earthquakes (0.4≤Ml≤4

  17. Timescales of ductility in an extensional shear zone recorded as diffusion profiles in deformed quartz

    NASA Astrophysics Data System (ADS)

    Nachlas, William; Teyssier, Christian; Whitney, Donna

    2015-04-01

    We document rutile needles that were in the process of exsolving from quartz during ductile shearing, and we apply the Arrhenius parameters for Ti diffusion in quartz to extract the timescales over which diffusion transpired. By constraining temperature conditions of deformation using multiple independent thermometers in the same rocks (Ti-in-quartz, Zr-in-rutile, quartz fabrics and microstructures), we estimate the longevity of a ductile shear zone that accommodated extensional collapse in the North American Cordillera. Eocene exhumation of the Pioneer core complex, Idaho, USA, was accommodated by the brittle-ductile Wildhorse detachment system that localized in a zone of sheared metasediments and juxtaposes lower crustal migmatite gneisses with upper crustal Paleozoic sedimentary units. Deformation in the Wildhorse detachment was partly accommodated within a continuous sequence (~200 m) of quartzite mylonites, wherein quartz grains are densely rutilated with microscopic rutile needles that are pervasively oriented into the lineation direction. We apply high-resolution spectroscopic CL analysis to map the Ti concentration field in quartz surrounding rutile needles, revealing depletion halos that indicate exsolution as Ti unmixes from quartz. Linear transects through depletion halos show that concentration profiles exhibit a characteristic diffusion geometry. We apply an error-function diffusion model to fit the measured profiles to extract the temperature or time recorded in the profile. Assuming modest temperature estimates from our combined thermometry analysis, results of diffusion modeling suggest that the quartzite shear zone was deforming over an integrated 0.8 - 3.1 Myr. If samples are permitted to have deformed in discrete intervals, our results suggest deformation of individual samples for timescales as short as 100 kyr. By comparing samples from different levels of the shear zone, we find that deformation was sustained in higher levels of the shear zone

  18. Displacement Addition on Linking Extensional Fault Arrays in the Canyonlands Graben, Utah

    NASA Astrophysics Data System (ADS)

    Commins, D. C.; Gupta, S.; Cartwright, J. A.; Phillips, W. M.

    2003-12-01

    Studies of brittle fault populations over the past decade have revealed that large extensional faults grow by the lengthening, interaction and physical linkage of en echelon fault segments. However, the temporal evolution of displacement accumulation during segment interaction and linkage is difficult to unravel due to a lack of direct observation during each stage in the fault array development. The process of profile re-adjustment prevents reconstruction of the growth history of a fault from its final configuration, and as a result, several models for the growth trajectory of a fault array undergoing linkage are possible. Observational data with which to constrain the relative timing and mode of displacement accumulation during the linkage process are currently lacking. We use the deformation of late Pleistocene-Holocene stream systems by the growth of a active normal faults in The Grabens, Canyonlands National Park, Utah to constrain the mode of growth of fault arrays. Coupling fault displacement data with geomorphic analysis of deformed present-day and palaeo-streams, permits sequential reconstruction of both simple 2-segment fault arrays and complex multi-segment populations from their initial component segments to the present day displacement geometry. In particular, these data provide information on the relative rates of displacement addition. For example, the presence of waterfalls where streams cross fault scarps indicates abrupt rates of displacement accumulation which we can relate to the hard linkage process. The reconstruction of both three- and six-segment faults reveal common aspects of displacement distribution through time: (1) Displacement accumulation occurs almost entirely in the interaction and linkage phase. (2) Interaction between segments causes enhanced displacement addition in overlap zones. (3) Despite interaction in the soft-linkage stage, faults do not achieve a characteristic profile during this phase (4) Displacement accrues rapidly

  19. Inter-rifting Deformation in an Extensional Rift Segment; the Northern Volcanic Zone, Iceland

    NASA Astrophysics Data System (ADS)

    Pedersen, R.; Masterlark, T.; Sigmundsson, F.; Arnadottir, T.; Feigl, K. L.

    2006-12-01

    The Northern Volcanic Zone (NVZ) in Iceland is an extensional rift segment, forming a sub-aerial exposure of a part of the Mid-Atlantic ridge. The NVZ is bounded to the south by the Icelandic mantle plume, currently beneath the Vatnajökull ice cap, and to the north by the Tjörnes Fracture zone, a transform zone connecting the offset on- and offshore rift segments of the Mid-Atlantic ridge. Based on geologic and tectonic mapping, the NVZ has been divided into five partly overlapping en-echelon fissure swarms, each with a central main volcanic production area. The two fissure swarms with known activity in historic time are, based on geodetic and seismic data, interpreted to have associated shallow crustal magma chambers. These central volcanoes are furthermore the only with caldera collapses associated, reflecting on the maturity of the systems. A series of newly formed InSAR images of the NVZ, spanning the interval from 1993-2006, have been formed, revealing a complex interplay of several tectonic and magmatic processes. Deformation from two subsiding shallow sources appear at the sites of the known crustal magma chambers. Furthermore, subsidence is occurring at varying degrees within the associated relatively narrow fissure swarms (15-20 km). However, the horizontal plate spreading signal is not confined to the fissure systems, and appears to be distributed over a much wider zone (about 100 km). This wide zone of horizontal spreading has previously been measured with campaign GPS surveys. A broad area of uplift situated about 18 km to the north of one of the subsidence centres (Krafla) suggests a deep seated pressurization source near the crust mantle boundary. Movements on previously unrecognized faults are apparent in the data, correlating well with the location of earthquake epicentres from minor seismic activity. Finally, utilization of geothermal resources in the Krafla area affects the deformation fields created by magmatic and tectonic processes, further

  20. Intensity of joints associated with an extensional fault zone: an estimation by poly3d .

    NASA Astrophysics Data System (ADS)

    Minelli, G.

    2003-04-01

    The presence and frequency of joints in sedimentary rocks strongly affects the mechanical and fluid flow properties of the host layers. Joints intensity is evaluated by spacing, S, the distance between neighbouring fractures, or by density, D = 1/S. Joint spacing in layered rocks is often linearly related to layer thickness T, with typical values of 0.5 T < S < 2.0 T . On the other hand, some field cases display very tight joints with S << T and nonlinear relations between spacing and thickness , most of these cases are related to joint system “genetically” related to a nearby fault zone. The present study by using the code Poly3D (Rock Fracture Project at Stanford), numerically explores the effect of the stress distribution in the neighbour of an extensional fault zone with respect to the mapped intensity of joints both in the hanging wall and in the foot wall of it (WILLEMSE, E. J. M., 1997; MARTEL, S. J, AND BOGER, W. A,; 1998). Poly3D is a C language computer program that calculates the displacements, strains and stresses induced in an elastic whole or half-space by planar, polygonal-shaped elements of displacement discontinuity (WILLEMSE, E. J. M., POLLARD, D. D., 2000) Dislocations of varying shapes may be combined to yield complex three-dimensional surfaces well-suited for modeling fractures, faults, and cavities in the earth's crust. The algebraic expressions for the elastic fields around a polygonal element are derived by superposing the solution for an angular dislocation in an elastic half-space. The field data have been collected in a quarry located close to Noci town (Puglia) by using the scan line methodology. In this quarry a platform limestone with a regular bedding with very few shale or marly intercalations displaced by a normal fault are exposed. The comparison between the mapped joints intensity and the calculated stress around the fault displays a good agreement. Nevertheless the intrinsic limitations (isotropic medium and elastic behaviour

  1. Diverse Primitive Basalts from an Extensional Back-arc Setting, Fort Rock Volcanic Field, Oregon.

    NASA Astrophysics Data System (ADS)

    Popoli, F. M., Jr.; Schmidt, M. E.

    2014-12-01

    The Pleistocene to Pliocene Fort Rock Volcanic Field (FRVF), situated in a back-arc extensional setting ~65 km east of the Central Oregon High Cascades has erupted a diverse array of basaltic magmas, including some primitive compositions with an Mg#>60. Major and trace element concentrations have been determined for 80 mafic bulk lava samples by X-ray Fluorescence (XRF) and selected minerals by electron microprobe. Petrological and geochemical data suggest three primitive basalt end-members similar to basalts in the nearby Oregon Cascade arc and High Lava Plains: high-alumina olivine tholeiite or low-K tholeiites (LKT), calc-alkaline basalts (CAB), ocean island basalts (OIB). Primitive Mg# (61-68) HAOTs are aphyric to phenocryst-poor (~2-5 %) olivine and plagioclase bearing and diktytaxitic. HAOTs are distinguished by low K2O (0.22-0.44 wt%), high Al2O3 (17.19-18.67 wt%) and CaO contents. CABs are the most dominant basalt type in the area with higher large ion lithophile element (LILE) concentrations (e.g., 170-426 ppm Ba) relative to high field strength elements (HFSE; 4.6-10.4 ppm Nb) and lower Mg#s (60-64) than HAOTs. CABs have more abundant (~5-15 %) and larger phenocrysts (~2-4 mm) of olivine and plagioclase than in HAOTs. OIBs contain higher Nb contents ranging from 11.7-18.6 ppm (vs. 3.0-7.2 ppm in HAOTs). OIBs are similar to both HAOTs and CABs, ranging from aphyric to porphyritic and diktytaxitic and may include amphibole phenocrysts. Tectonic extension associated with the Basin and Range in this area likely facilitated eruptions of primitive magmas. A comparison of the most primitive magmas (HAOTs with Mg#>65) found in eastern and western FRVF indicates that the western HAOTs contain higher incompatible element concentrations relative to eastern HAOT (Ba, Sc, Sr, Zr, Nb), which may reflect lower degrees of melting of a more enriched mantle source to the west.

  2. Sedimentary response to tectonism in the extensional Chihuahua trough, Cretaceous of Southern North America

    NASA Astrophysics Data System (ADS)

    Budhathoki, P.; Langford, R. P.; Pavlis, T. L.

    2009-12-01

    During the Jurassic and Cretaceous, the Chihuahua Trough formed an extensional basin, extending from the Gulf of Mexico to Southern Arizona, along the Present Border of the United States and Mexico. West of the Big Bend of Texas, Jurassic and Cretaceous sediments are less than 150 m thick, and in many areas are absent. The sedimentary package thickens to over 3km within the trough. The Albian Cox Sandstone is one of the most areally extensive formations and consists of interbedded fluvial coastal and shallow marine sandstones and shales. In this study area, shales (10-70 m) are thicker more than sandstone beds (2-10 m). This unit is overlain by Finlay formation, a fine crystalline gray limestone and underlain by Bluff Mesa formation, a fossiliferous shallow marine limestone. Cross-bedded, brown, fine to medium grained sandstone, interbedded with siltstone, shale and limestone are characteristic lithology of the Cox. The Indio Mountains of Trans-Pecos Texas offer an ideal location to study how this package accommodates the deformation associated with the subsiding Chihuahua trough. A continuous outcrop extends over 30 km oblique to the basin margin and thickens from approximately 375 m on the northern side to 437 m on the southern side of the 10 km section studied so far. One important mechanism is rotation of the strata into the basin, followed by truncation along sequence boundaries. The lower two sequence in the southern Indio mountains are rotated down to the basin relative to Finlay. The lowest sequences thicken from an erosional pinch out towards the South. Shale beds thicken within the rotated strata and accommodate some of the tilting. For example, Thickness of the shale bed varies from 18 m to 70 m within a 2 km distance. However, erosional truncation of the tilted strata accounts for most of the increases in thickness within sequences. The base of the formation has been rotated about 6 degrees south relative to the top of the formation. Another observed

  3. Ductile strain rate recorded in the Symvolon syn-extensional plutonic body (Rhodope core complex, Greece)

    NASA Astrophysics Data System (ADS)

    Cirrincione, Rosolino; Fazio, Eugenio; Ortolano, Gaetano; Fiannacca, Patrizia; Kern, Hartmut; Mengel, Kurt; Pezzino, Antonino; Punturo, Rosalda

    2016-04-01

    Sciences, 90 (1), 77-87. • Punturo, R., Cirrincione, R., Fazio, E., Fiannacca, P., Kern, H., Mengel, K., Ortolano G., and Pezzino, A. (2014). Microstructural, compositional and petrophysical properties of mylonitic granodiorites from an extensional shear zone (Rhodope Core complex, Greece). Geological Magazine, 151 (6), 1051-1071.

  4. The tectonic evolution of Southeast Asia through accretionary and extensional episodes since the Cretaceous

    NASA Astrophysics Data System (ADS)

    Seton, M.; Zahirovic, S.; Müller, R.

    2012-12-01

    Although a number of tectonic reconstructions exist that document the development of the present-day complex assemblage of exotic terranes in Southeast Asia, very few describe the continuously evolving plate boundaries and the geodynamic driving forces in the region. We propose a plate motion model that attempts to reconcile evidence from both surface geology and the subsurface mantle structure, and implement continuously closing plate polygons using our open-source plate reconstruction software, GPlates, for the eastern Asian margin and eastern Tethyan domain since the Cretaceous. We link the change from a compressional to an extensional regime along eastern Asia in the Late Cretaceous as the likely opening of the Proto South China Sea in a back-arc setting to account for obducted ophiolite sections on Palawan that are Cretaceous in age, with a likely Miocene emplacement resulting from subduction of the Proto South China Sea crust. Such an interpretation is also consistent with the timing of accretionary episodes along northern Borneo and the upper mantle slab visible in P-wave seismic tomography models. The development of Sundaland is also intricately linked to the opening of the Proto South China Sea and the accretion of Gondwana-derived micro-continental blocks, including East Java and West Sulawesi, in the Cretaceous. Whether Sundaland behaved as a rigid cohesive block, or whether Borneo rotated and moved relative to Sundaland has been a matter of debate due to inconsistencies between paleomagnetic and structural data. Paleomagnetic results indicate significant rotations of Borneo that are accommodated by oroclinal bending without the need for bounding transform faults, which are not obvious in both seismic and potential field data. In the absence of preserved seafloor, we use geological evidence such as ophiolite emplacements, magmatic episodes, paleomagnetic constraints, structural reactivation and deformation as proxies to build a self-consistent plate

  5. Assessment of undiscovered oil and gas resources of the East Coast Mesozoic basins of the Piedmont, Blue Ridge Thrust Belt, Atlantic Coastal Plain, and New England Provinces, 2011

    USGS Publications Warehouse

    Milici, Robert C.; Coleman, James L.; Rowan, Elisabeth L.; Cook, Troy A.; Charpentier, Ronald R.; Kirschbaum, Mark A.; Klett, Timothy R.; Pollastro, Richard M.; Schenk, Christopher J.

    2012-01-01

    During the early opening of the Atlantic Ocean in the Mesozoic Era, numerous extensional basins formed along the eastern margin of the North American continent from Florida northward to New England and parts of adjacent Canada. The basins extend generally from the offshore Atlantic continental margin westward beneath the Atlantic Coastal Plain to the Appalachian Mountains. Using a geology-based assessment method, the U.S. Geological Survey estimated a mean undiscovered natural gas resource of 3,860 billion cubic feet and a mean undiscovered natural gas liquids resource of 135 million barrels in continuous accumulations within five of the East Coast Mesozoic basins: the Deep River, Dan River-Danville, and Richmond basins, which are within the Piedmont Province of North Carolina and Virginia; the Taylorsville basin, which is almost entirely within the Atlantic Coastal Plain Province of Virginia and Maryland; and the southern part of the Newark basin (herein referred to as the South Newark basin), which is within the Blue Ridge Thrust Belt Province of New Jersey. The provinces, which contain these extensional basins, extend across parts of Georgia, South Carolina, North Carolina, Virginia, Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut, and Massachusetts.

  6. Air and seawater pollution and air-sea gas exchange of persistent toxic substances in the Aegean Sea: spatial trends of PAHs, PCBs, OCPs and PBDEs.

    PubMed

    Lammel, Gerhard; Audy, Ondřej; Besis, Athanasios; Efstathiou, Christos; Eleftheriadis, Kostas; Kohoutek, Jiři; Kukučka, Petr; Mulder, Marie D; Přibylová, Petra; Prokeš, Roman; Rusina, Tatsiana P; Samara, Constantini; Sofuoglu, Aysun; Sofuoglu, Sait C; Taşdemir, Yücel; Vassilatou, Vassiliki; Voutsa, Dimitra; Vrana, Branislav

    2015-08-01

    Near-ground air (26 substances) and surface seawater (55 substances) concentrations of persistent toxic substances (PTS) were determined in July 2012 in a coordinated and coherent way around the Aegean Sea based on passive air (10 sites in 5 areas) and water (4 sites in 2 areas) sampling. The direction of air-sea exchange was determined for 18 PTS. Identical samplers were deployed at all sites and were analysed at one laboratory. hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs) as well as dichlorodiphenyltrichloroethane (DDT) and its degradation products are evenly distributed in the air of the whole region. Air concentrations of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and o,p'-DDT and seawater concentrations of p,p'-DDE and p,p'-DDD were elevated in Thermaikos Gulf, northwestern Aegean Sea. The polychlorinated biphenyl (PCB) congener pattern in air is identical throughout the region, while polybrominated diphenylether (PBDE)patterns are obviously dissimilar between Greece and Turkey. Various pollutants, polycyclic aromatic hydrocarbons (PAHs), PCBs, DDE, and penta- and hexachlorobenzene are found close to phase equilibrium or net-volatilisational (upward flux), similarly at a remote site (on Crete) and in the more polluted Thermaikos Gulf. The results suggest that effective passive air sampling volumes may not be representative across sites when PAHs significantly partitioning to the particulate phase are included.

  7. Extensional vs contractional Cenozoic deformation in Ibiza (Balearic Promontory, Spain): Integration in the West Mediterranean back-arc setting

    NASA Astrophysics Data System (ADS)

    Etheve, Nathalie; Frizon de Lamotte, Dominique; Mohn, Geoffroy; Martos, Raquel; Roca, Eduard; Blanpied, Christian

    2016-07-01

    Based on field work and seismic reflection data, we investigate the Cenozoic tectono-sedimentary evolution offshore and onshore Ibiza allowing the proposal of a new tectonic agenda for the region and its integration in the geodynamic history of the West Mediterranean. The late Oligocene-early Miocene rifting event, which characterizes the Valencia Trough and the Algerian Basin, located north and south of the study area respectively, is also present in Ibiza and particularly well-expressed in the northern part of the island. Among these two rifted basins initiated in the frame of the European Cenozoic Rift System, the Valencia Trough failed rapidly while the Algerian Basin evolved after as a back-arc basin related to the subduction of the Alpine-Maghrebian Tethys. The subsequent middle Miocene compressional deformation was localized by the previous extensional faults, which were either inverted or passively translated depending on their initial orientation. Despite the lateral continuity between the External Betics and the Balearic Promontory, it appears from restored maps that this tectonic event cannot be directly related to the Betic orogen, but results from compressive stresses transmitted through the Algerian Basin. A still active back-arc asthenospheric rise likely explains the stiff behavior of this basin, which has remained poorly deformed up to recent time. During the late Miocene a new extensional episode reworked the southern part of the Balearic Promontory. It is suggested that this extensional deformation developed in a trans-tensional context related to the westward translation of the Alboran Domain and the coeval right-lateral strike-slip movement along the Emile Baudot Escarpment bounding the Algerian Basin to the north.

  8. Subsidence history, crustal structure, and thermal evolution of the Valencia Trough: A young extensional basin in the western Mediterranean

    SciTech Connect

    Watts, A.B. ); Torne, M. Consejo Superior de Investigaciones Cientificas, Barcelona )

    1992-12-10

    The Valencia Trough is an extensional basin that began rifting during the late Oligocene-early Miocene, yet it is located within a region of compression between the European and African plates. Seismic reflection, seismic refraction, well, gravity, and geoid data have been used to determine the relative importance of extensional and compressional processes in controlling the structure and evolution of the trough. Although the trough appears symmetric on bathymetric maps, seismic and gravity and geoid data indicate a fundamental asymmetry in its deep crustal and upper mantle structure. Two dimensional flexural backstripping techniques have been used to estimate the total amount of crustal stretching along a transect of the trough between the Catalan Coastal Ranges and Mallorca. There is good agreement between the predicted depth to the Moho based on a stretching model and the seismically constrained depth beneath the Catalan margin, but poor agreement beneath Mallorca. The seismic Moho beneath Mallorca can be explained by a model in which the crust was modified by the flexural effects of thrust/fold loading. Geoid data suggest that the differences in the crustal structure between the two margins extend into the upper mantle. The Catalan margin is characterized by a thermal and mechanical boundary, which markes the transition between cold, unstretched lithosphere and hot, thin lithosphere, while Mallorca is located above a broad region of lithospheric thinning. The subsidence history and amount of crustal thinning in the Catalan margin resemble that of typical Atlantic-type nonvolcanic margin. However, a narrow transition zone (< 60 km), the lack of any evidence for a conjugate margin, and the absence of oceanic crust suggest fundamental diffeences in the way that extensional processes may occur in convergent plate settings.

  9. Permian evolution of sandstone composition in a complex back-arc extensional to foreland basin: The Bowen Basin, eastern Australia

    SciTech Connect

    Baker, J.C. . Centre for Microscopy and Microanalysis); Fielding, C.R. . Dept. of Earth Sciences); Caritat, P de . Dept. of Geology); Wilkinson, M.M. )

    1993-09-01

    The Bowen Basin is a Permo-Triassic, back-arc extensional to foreland basin that developed landward of an intermittently active continental volcanic arc associated with the eastern Australian convergent plate margin. The basin has a complex, polyphase tectonic history that began with limited back-arc crustal extension during the Early Permian. This created a series of north-trending grabens and half grabens which, in the west, accommodated quartz-rich sediment derived locally from surrounding, uplifted continental basement. In the east, coeval calc-alkaline, volcanolithic-rich, and volcaniclastic sediment was derived from the active volcanic arc. This early extensional episode was followed by a phase of passive thermal subsidence accompanied by episodic compression during the late Early Permian to early Late Permian, with little contemporaneous volcanism. In the west, quartzose sediment was shed from stable, polymictic, continental basement immediately to the west and south of the basin, whereas volcanolithic-rich sediment that entered the eastern side of the basin during this time was presumably derived from the inactive, and possibly partly submerged volcanic arc. During the late Late Permian, flexural loading and increased compression occurred along the eastern margin of the Bowen Basin, and renewed volcanism took place in the arc system to the east. Reactivation of this arc led to westward and southward spread of volcanolithic-rich sediment over the entire basin. Accordingly, areas in the west that were earlier receiving quartzose, craton-derived sediment from the west and south were overwhelmed by volcanolithic-rich, arc-derived sediment from the east and north. This transition from quartz-rich, craton-derived sediments to volcanolithic-rich, arc-derived sediments is consistent with the interpreted back-arc extensional to foreland basin origin for the Bowen Basin.

  10. Thermal, chemical and isotopic homogenization of syn-extensional I-type plutons and mafic microgranular enclaves

    NASA Astrophysics Data System (ADS)

    Tatar Erkül, Sibel; Erkül, Fuat; Uysal, İbrahim

    2015-04-01

    Magma mixing and mingling processes are common phenomenon in the evolution of granitoid magmas. This study deals with examination of mineral chemical, geochemical and isotopic characteristics of enclaves and enclosing syn-extensional granite bodies in western Turkey to make an attempt to solve problems regarding their origin. Mafic microgranular enclaves have granodiorite, quartz monzonite, monzonite and monzodiorite compositions, are subalkaline/calc-alkaline and high-K in character and display typical mixing/mingling textures. Mafic enclaves have partially overlapping geochemical characteristics onto their host rocks in terms of mobile elements and their isotopes while distinct immobile element patterns occur within host rocks and enclaves. Contrasting geochemistry of enclaves is mainly defined by their low SiO2 and high MgO, Mg# and high Fe2O3 contents. Chondrite-normalized spidergrams of enclaves also reveal two contrasting patterns. One is relatively enriched in rare earth element content and the other is slightly enriched and displays relatively flat pattern. 87Sr/86Sr and 143Nd/144Nd contents of enclaves imply considerable amount of crustal input. Crustally derived felsic magma coeval with mafic magma have been chemically, thermally and mechanically exchanged with each other and resulting homogenization led to compositional and isotopic equilibration of mafic and felsic magmas. Fractional crystallization, mixing and the following crustal contamination were responsible for the final composition of syn-extensional granitoids. Such processes appear to have been widely occurred in continental extensional regime that caused melting and mixing of crustal and mantle sources at MOHO depth.

  11. Mantle-derived CO2 migration along active faults within an extensional basin margin (Fiumicino, Rome, Italy)

    NASA Astrophysics Data System (ADS)

    Bigi, S.; Beaubien, S. E.; Ciotoli, G.; D'Ambrogi, C.; Doglioni, C.; Ferrante, V.; Lombardi, S.; Milli, S.; Orlando, L.; Ruggiero, L.; Tartarello, M. C.; Sacco, P.

    2014-12-01

    Fluid migration along faults can be highly complex and spatially variable, with the potential for channeled flow, accumulation in capped porous units, fault cross-flow, lateral migration along strike, or complete sealing. Extensional basin margins can be important for such migration, given the associated crustal thinning and decompression that takes place combined with potential geothermal or mantle gas sources. One such example is near the urban area of Rome, situated along the active extensional continental margin of the Tyrrhenian back arc basin and surrounded by Middle-Upper Pleistocene K-rich and arc-related volcanoes. Recent research activities in the area around Fiumicino, a town 25 km to the west of Rome, has highlighted the close spatial link between degassing CO2 and the faults that provide the necessary vertical migration pathways. In particular, detailed soil gas and gas flux surveys have highlighted the release at surface of large volumes of asthenospheric mantle CO2 in correspondence with normal faults observed in a new seismic reflection profile acquired along the Tiber River. Detailed reconstruction of the Pleistocene-Holocene stratigraphy of the area dates fault activity from 20,000 to 9000 years BP. It is proposed that the gas migrates preferentially along the cataclastic tectonic breccias of the faults until it encounters recent, unconsolidated sediments; porous units within this shallow stratigraphy act as temporary secondary traps for the leaking gas, with local gas release at the ground surface occurring where the sealing of the overlying aquitards has been compromised. Degassing and active faults confirm the extensional tectonics affecting the area and the geodynamic scenario of a mantle wedge beneath the western Apennines, associated with ongoing W-directed subduction. Moreover, degassing highlights the potential geochemical and seismic risks for the highly populated urban areas near Rome.

  12. Superposed local and regional paleostresses: Fault-slip analysis of Neogene extensional faulting near coeval caldera complexes, Yucca Flat, Nevada

    SciTech Connect

    Minor, S.A.

    1995-06-10

    Numerous reduced stress tensors are computed by multiple inversions of 906 temporally and spatially partitioned fault-slip data from the Yucca Flat region in the southwest Nevada volcanic field to constrain the Neogene paleostress and faulting history and to investigate how the regional tectonic stress field was affected by local caldera magmatism. Perturbed, shallow (<400 m), pre-11 Ma paleostress configurations, determined west and northwest of present (post-11 Ma) Yucca Flat basin, existed during mild extensional faulting and are attributed to superposition of transient caldera-magmatic stresses on the regional stress field. A brief ({approximately} 0.5 m.y.) change to a strike-slip stress state occurred at about 13 Ma and was accompanied by small-offset, quasi-conjugate strike-slip faulting. This stress state was most distinct, relative to a normalslip state, near calderas where stress solutions and fault relations indicate closer affinities to a reverse-slip state. Inferred 11.6-11.45 Ma paleostress tensors indicate radial tension associated with either initial caldera collapse or local post-collapse topographic modification of the stress field. Post-11 Ma normal-slip stress tensors are associated with normal- and oblique-slip faults that accommodated subsidence and eastward extension of Yucca Flat basin away from the caldera complexes. These tensors do not indicate stress modifications due to residual caldera-related effects and thus were used to infer post-11 Ma regional stress changes. The stress field has rotated as much as 65{degrees} clockwise since 11 Ma during extensional development of Yucca Flat basin, with most of the rotation and extension occurring before about 8.5 Ma. Results suggest that shallow magmatism and caldera development can strongly alter extensional tectonic stress fields, fault patterns, and slip directions in the uppermost crust out to distances of roughly two magma chamber radii away from a magma body. 59 refs., 11 figs., 2 tabs.

  13. Assessment of SMOS Salinity and SST in the Aegean Sea (Greece) and correlations with MODIS SST measurements. Exploring the SSS and SST correlation to 137Cs inventory

    NASA Astrophysics Data System (ADS)

    Sykioti, Olga; Florou, Heleni

    2014-05-01

    A program concept has been developed to utilize sea surface salinity (SSS) and sea surface temperature (SST) information for the inventory of artificial radionuclides, which are conservative and part of the sea salinity. As a pilot study, activity concentrations of 137Cs in the Aegean Sea (Greece) are combined to SMOS and other satellite data so as to develop an innovative tool for the remote radioactivity detection either for routine observations and emergency recordings. The presented first results are a part of an effort to attempt for the integration in space and time of field measurements to the respective satellite observations of salinity variations by model simulations, which might be also applicable for the prediction of the radiological impact of potential accidental events. The presented results involve the first assessment of SMOS SSS and SST measurements over the Aegean Sea. SMOS measurements are averaged over a surface of 40x40 sq km at an average distance of 100 km from the coastline. For this reason, totally thirty nine pixels from SMOS Level 2 data cover part of the Aegean Sea. Two time series are created that include all available measurements spanning December 2011 to current date, from descending and ascending passes, each one representing an acquisition frequency of about three days. The average SSS values in the Aegean Sea are 37-38psu following no distinct seasonal pattern. A general trend of increasing values is observed from north to south. Noise and uncertainty in the measurements are most probably due to land and RFI contamination. High island density is combined with radiofrequency interferences generated by illegal man-made emissions. The latter is a detected common issue in specific areas worldwide, such as the Mediterranean Sea. On the other hand, SST follows a clear typical seasonal variation pattern with maximum values observed in August and minimum ones around March and a general trend of increasing values from north to south

  14. Proterozoic extensional tectonics of the central Fennoscandian Shield: Results from the Baltic and Bothnian Echoes from the Lithosphere experiment

    NASA Astrophysics Data System (ADS)

    Korja, A.; Heikkinen, P. J.

    1995-04-01

    A three-dimensional crustal structure of the Bothnian Sea is deduced from the near-vertical reflection data of the crosscutting lines 1, 6, 7, and C of the BABEL (BAltic and Bothnian Echoes from the Lithosphere) experiment. For this study the common depth point stacked sections have been migrated with a velocity 6.5 km/s and displayed as stacked envelope sections to show their enhanced large-scale crustal structures. The seismic sections show listric shear zones which dip toward SE and flatten at major detachment zones 35-40 km and 48 km in depth. The detachment zones are associated with changes in P wave velocity from 6.8 km/s to 7.0 km/s and from 7.4 km/s to 8.2 km/s and coincide with the middle and lower crustal boundary and the Moho boundary, respectively. The geometry and crosscutting relationship of the detachment zone are well developed on the E-W directed line 7, from where the Moho detachment zone can be interpreted as to be younger. Different shear zone systems operated in the parallel N-S directed lines 1 and 6, and therefore it is not easy to correlate crustal structures between lines 1 and 6. In the thinned southern part of study area, the lower crust has a highly reflective lamellar structure and a strongly reflective subhorizontal Moho. Increased reflectivity of the lower crust is attributed to stretching and mafic underplating of the crust associated with the Subjotnian diabase dykes and rapakivi magmatism. In the upper crust the rapakivi granite and diabase association is characterized by a rather transparent area within which strong reflections mimic graben and horst structures. The distribution of the bimodal association seems to be controlled by the low-angle listric shear zones. The spatial distribution of outcropping lithologies combined with deeply penetrating shear zones suggests a simple shear extensional deformation. The first stage of deformation, which concentrated in the upper and middle crust, records the collapse of the overthickened

  15. Evolution and fluxes of 137Cs in the Black Sea/Turkish Straits System/North Aegean Sea

    NASA Astrophysics Data System (ADS)

    Delfanti, R.; Özsoy, E.; Kaberi, H.; Schirone, A.; Salvi, S.; Conte, F.; Tsabaris, C.; Papucci, C.

    2014-07-01

    The vertical profiles of 137Cs were determined in the North Aegean, Marmara and Black Seas, to assess inventories and fluxes of the radionuclide in these basins. The inventory of 137Cs in the Western Black Sea integrated from the surface down to 400 m water depth is 3.4 ± 0.1 kBq m- 2, which is surprisingly close to the amount determined in 1988, decay corrected to 2007 (2.9 ± 0.1 kBq m- 2). On the other hand, based on the comparison of profiles roughly 20 years apart, it is estimated that about 1 kBq m- 2 has been transferred from above the halocline to depths below the halocline, emphasizing the effective redistribution of tracers within the same period. We estimate that about 12 TBq y- 1 of 137Cs presently leaves the Black Sea with the upper layer flow through the Bosphorus and only 2 TBq y- 1 is returned with the lower layer inflow of Mediterranean water from the Marmara Sea. Accounting for river fluxes, estimated on the order of 2 TBq y- 1 few years after the Chernobyl accident, and possibly decreased by now, we can thus estimate a net rate of loss of about 8-10 TBq y- 1. Investigating the effective redistribution in the upper water column, the supply by the inflowing Mediterranean water alone does not explain the increase of 137Cs concentration and inventory at intermediate depths in the Western Black Sea. The most important mechanism transferring 137Cs and dissolved contaminants from the surface water to the sub-pycnocline layer appears to be the turbulent entrainment of a larger quantity of Black Sea water into the inflowing plume of Mediterranean water through mixing processes on the southwestern shelf and continental slope following its exit from the Bosphorus. This process produces an extra export of some10 TBq y- 1 of 137Cs from the surface to the sub-pycnocline depths of the Black Sea, a quantity comparable in magnitude to the total export out from the basin. It is the entrainment flux resulting from the mixing, and the further advection and

  16. Depositional environment, foraminifer content and ESR ages of Quaternary Gediz Delta Sediments (Eastern Aegean Sea, İzmir-Western Turkey)

    NASA Astrophysics Data System (ADS)

    Gökçe Benli, Ekin; Aydın, Hülya; İşintek, İsmail; Engin, Birol; Şengöçmen, Berna

    2016-04-01

    Sediments and fossil content of Gediz Delta (Eastern Aegean Sea - İzmir) were examined based on the drilling core samples of the YSK-C and SK-246 drilling. W-SW part of the Delta is represented by continental delta sediments up to 6 meters and shallow marine detritic sediments up to 35 meters in the YSK-C drilling. Continental part consists of an soiled, graveled, muddy and sandy sediment in terms of rich organic substance. As for marine part, it consists of bioclast, muddy, fine graveled sand and by repetition of pebble, sand and bioclast bearing mud layers. Bioclasts comprise of bivalvia, echinoid, ostracod, gastropod, foramifer and bryozoa fragments. Benthic foraminiferal fauna determinated in the marine levels are represented by 55 bethic, 2 planktonic species. These foraminifers and bioclasts reflect that the W-SW part of the delta, has been occured in marine conditions between 8-31m deep. E-NE part of the delta is generally represented by continental sediments up to 43.5m in SK-246 drilling. In addition, it includes marine levels in 18-19 m, 23-24 m and 36-37,5 m intervals. Continental sediments of E-NE part is generally represented by calcareous and sandy mud rocks which mostly includes ash, tuff, and pebble derived from Neogene volcanic rocks. As for marine levels, it is composed of calcareous mud stones and calcareous clay stones including very thin gastropod, bivalvia and ostracod in 18- 19 and 36-37.5 meters whereas it is represented by sandy mud stones including a great deal of bentic foraminifer, bivalvia, bryozoa, echinoid, gastropod in 23-24 metres. Thus show that E-NE part of the delta is usually in continental condition but it is occasionally covered by sea. In aging studies of YSK-C core done by ESR method, age of 8-9 m interval is determined to be 11. 376 ± 0,067 Ka; however ages of 10-11m and 24-25 m intervals are revealed to be 16.466 ± 0,016 Ka and 15.344 ± 0,021 Ka respectively; finally age of 25-26 m interval is found to be 19.995 ± 0

  17. Quantitative analysis of the extensional tectonics of Tharsis bulge, Mars - Geodynamic implications

    NASA Astrophysics Data System (ADS)

    Thomas, P. G.; Allemand, P.

    1993-07-01

    The amount of horizontal strain on the Martian Tharsis bulge is quantified in order to provide further information on the tectonic evolution of this province. About 10 percent of the Tharsis surface bulge exhibits elliptical impact craters, which are the largest strain markers in the solar system. It is shown that these strain ellipses indicate more strain than could be due to the bulge building alone. The existence of such intensely deformed areas, the direction of the extensive strain, the localization of these areas on the bulge crest or on the top of topographic slopes, and the evidence of nonthinned crust under these areas may all be explained by gravitational slidings of the bulge surface over the topographic slope. This sliding would be possible because of the presence of a decollement level two kilometers below the surface, and because of the prefracturation which have made the detachment possible.

  18. Evidence for Neoarchaean extensional faults in the Vredefort Dome, South Africa.

    NASA Astrophysics Data System (ADS)

    mashabela, sello

    2013-04-01

    -2643 Ma) of the Ventersdorp Supergroup. The association potentially means that the Vredefort collar hosts rotated Ventersdorp-age extensional faults or a rift system of faults that predate impact-induced structures. 1. Manzi, M.S.D., Durrheim, R.J., Hein, K.A.A., King N., 2012. 3D edge detection seismic attributes used to map potential conduits for water and methane in deep gold mines in the Witwatersrand basin, South Africa. Geophysics 77 (5), 1-16. 2. Manzi, M., Gibson, M. A.S., Hein, K.A.A., King, N., Durrheim, R.J., 2012. Application of 3D Seismic techniques in evaluation of ore resources in the West Wits Line goldfield and portions of the West Rand Goldfield, South Africa. Geophysics 77, 1-9. 3. Manzi, M., Hein, K.A.A., King, N, Durrheim, R.J., submitted. NeoArchaean tectonic history of the Witwatersrand Basin and Ventersdorp Supergroup: New Constraints from high-resolution 3D seismic reflection data. Tectonophysics

  19. The continental Etirol-Levaz slice (Western Alps, Italy): Tectonometamorphic evolution of an extensional allochthon

    NASA Astrophysics Data System (ADS)

    Ewerling, Kathrin; Obermüller, Gerrit; Kirst, Frederik; Froitzheim, Nikolaus; Nagel, Thorsten; Sandmann, Sascha

    2013-04-01

    The Etirol-Levaz slice (ELS) in the western Valtournenche of Italy is a continental fragment trapped between two oceanic units, the eclogite-facies Zermatt-Saas Zone in the footwall and the greenschist-facies Combin Zone in the hanging wall. It has been interpreted as an extensional allochthon derived from the Adriatic continental margin and stranded inside the Piemont-Ligurian oceanic domain during Jurassic rifting (Dal Piaz et al., 2001; Beltrando et al., 2010). The slice consists of Variscan high-grade gneisses, micaschists and metabasics overprinted under eclogite-facies conditions during Early Tertiary Alpine subduction. Eclogites generally consist of garnet + omphacite ± epidote ± amphibole ± phengite ± quartz. We investigate their metamorphic history using equilibrium phase diagrams, mineral compositions, and textural relations between prograde, peak, and retrograde phases. In sample FD328, garnets have compositions of Alm52-61 Grs18-41 Prp5-22 Sps0.5-2 and typical growth zoning. Some garnet grains are brittlely fractured, strongly corroded and overgrown by epidote. Amphibole occurs as a major phase in the matrix and shows a progressive evolution from glaucophane in the core to pargasitic hornblende towards the rim. Sample FD329 with a particular Ca-rich bulk composition (18.3 wt% Ca) displays two distinct garnet generations. Perfectly euhedral cores show compositions of Grs42-45 Alm47-51 Prp3-6 Sps2-7 and typical prograde growth zoning. These cores are overgrown by irregularly shaped rims characterised by an initial rise in Mn and the Fe-Mg ratio. Omphacite in this sample with jadeite-contents of 19-28 mol% apparently has been fractured and annealed by jadeite-poor (7-12 mol%) omphacite suggesting brittle behaviour at eclogite-facies conditions or two high-pressure stages with lower metamorphic conditions in between. We discuss whether the ELS experienced the same monocyclic metamorphic history as the Zermatt-Saas Zone or not. Some of our observations

  20. Relation between ore-forming hydrothermal systems and extensional deformation in the Solea graben spreading center, Troodos ophiolite, Cyprus

    NASA Astrophysics Data System (ADS)

    Bettison-Varga, Lori; Varga, Robert J.; Schiffman, Peter

    1992-11-01

    Field relations indicate that high-temperature hydrothermal circulation and accumulation of massive sulfide deposits within the Solea graben of the Troodos ophiolite, Cyprus, followed extreme crustal attenuation. Zones of pervasive, massive epidosite strike parallel to the axis of the Solea graben and to the strike of extensional normal faults. Initial fluid flow, evidenced by preferential epidotization in weakly altered areas surrounding massively altered regions, was focused along joints, microfractures, and (now) low-angle normal-fault zones related to graben formation. Permeability within the sheeted-dike section was enhanced by brittle deformation related to extensional structures as well as through volume reduction inherent in the diabase to epidosite mineralogic phase transformations. Intrusion of high-level gabbros into epidosite zones occurred both before and after significant amagmatic tectonic extension. Structural control on epidotization suggests that intrusion of late stocks into attenuated and highly deformed crust is necessary to drive the vigorous hydrothermal circulation that produced the epidosites and ore bodies of the Solea graben. A similar sequence of events is more likely to occur in the modern oceans along ridge crests with ephemeral magmatism, especially at intermediate- to slow-spreading ridges near transform faults.

  1. Fabric evidence for granodiorite emplacement with extensional shear zones in the Variscan Gredos massif (Spanish Central System)

    NASA Astrophysics Data System (ADS)

    Díaz-Alvarado, Juan; Fernández, Carlos; Díaz-Azpiroz, Manuel; Castro, Antonio; Moreno-Ventas, Ignacio

    2012-09-01

    Three granitoid bodies in the central part of the Gredos massif (Spanish Central System batholith) are tabular, around 1 km in thickness, and intruded into a migmatitic middle crust during the D3 deformation phase of the Variscan Orogeny. Petrologically, they are composed of Bt-granodiorite and Crd-monzogranite, and they show varying abundance of large (cm-scale) feldspar megacrysts. A detailed study of the shape preferred orientation (SPO) magmatic fabric defined by these megacrysts, together with a kinematic analysis of the structures due to interactions between them, and the measurement of quartz c-axis fabrics in migmatites and granitoids, suggests that granitic magma and country rocks were mechanically coupled during deformation. The emplacement took place along large-scale, extensional shear zones active during the first stages of the D3 phase. The shape of the SPO ellipsoids varies from constrictional at the centre of the granitic bodies, to flattening or even oblate at their external contacts with the migmatitic host rocks. The favoured interpretation of this spatial fabric variation is the overprinting of the emplacement fabrics by a constrictional tectonic regime associated with the growth of tabular magma chambers along extensional detachments, followed by shear zone development commonly at the top of the granitic bodies. The entire structure was later folded during the last stages of the D3 phase.

  2. Time interval between volcanism and burial metamorphism and rate of basin subsidence in a Cretaceous Andean extensional setting

    NASA Astrophysics Data System (ADS)

    Aguirre, L.; Féraud, G.; Morata, D.; Vergara, M.; Robinson, D.

    1999-11-01

    40Ar/ 39Ar ages were obtained from basaltic flows belonging to a 9-km-thick sequence generated in an extensional ensialic setting of an arc/back-arc basin type during the Early Cretaceous and presently exposed along the Coastal Range of central Chile. The basalts have been affected by very low- to low-grade burial metamorphism, mostly under prehnite-pumpellyite facies. Age values obtained from primary (volcanic) and secondary (metamorphic) minerals permit to quantify the time interval between volcanism and burial metamorphism. A plateau age of 119±1.2 Ma from primary plagioclase represents the best estimation of the age of the volcanism, whereas adularia, in low-variance assemblages contained in amygdules, gave a plateau age of 93.1±0.3 Ma which is interpreted as the age of the metamorphism. Considering the P- T conditions estimated for this metamorphic event, the c. 25 Ma time interval between volcanic emplacement and prehnite-pumpellyite facies metamorphism, the rate of basin subsidence in this extensional geodynamic setting would be comprised in the interval 150-180 m/Ma.

  3. The relationship of extensional and compressional tectonics to a Precambrian fracture system in the eastern overthrust belt, USA

    NASA Technical Reports Server (NTRS)

    Pohn, H.

    1985-01-01

    The central and southern Appalachians have a long history of interrelated extensional and compressional tectonics. It is proposed that each episode was controlled by a reactivation of a fracture system in the Precambrian basement. Proprietary seismic-reflection profiles show a system of down-to-the-east Precambrian extensional faults. When under renewed extension, these faults produce features such as the western border faults of Mesozoic basins, and when under compression, probably produce tectonic ramps in the overlying sedimentary cover rocks as well as the spatially and genetically related Alleghenian folds. This system, which parallels the Appalachian trend, is cut by a system of cross-strike hinge or scissors faults that have probable strike-slip movements. Reactivation of this cross-strike system appears to have produced lateral ramps that connect decollements at different stratigraphic levels and caused abrupt changes in fold wavelength along strikes. Continued reactivation of this cross-strike system is suggested by east-west border faults and Precambrian highs between Mesozoic basins. The present activity of this system is suggested by the fact that more than 35% of recent earthquakes are coincident with cross-strike faults and lateral ramps.

  4. The Pinto shear zone; a Laramide synconvergent extensional shear zone in the Mojave Desert region of the southwestern United States

    NASA Astrophysics Data System (ADS)

    Wells, Michael L.; Beyene, Mengesha A.; Spell, Terry L.; Kula, Joseph L.; Miller, David M.; Zanetti, Kathleen A.

    2005-09-01

    The Pinto shear zone is one of several Late Cretaceous shear zones within the eastern fringe of the Mesozoic magmatic arc of the southwest Cordilleran orogen that developed synchronous with continued plate convergence and backarc shortening. We demonstrate an extensional origin for the shear zone by describing the shear-zone geometry and kinematics, hanging wall deformation style, progressive changes in deformation temperature, and differences in hanging wall and footwall thermal histories. Deformation is constrained between ˜74 and 68 Ma by 40Ar/ 39Ar thermochronology of the exhumed footwall, including multi-diffusion domain modeling of K-feldspar. We discount the interpretations, applied in other areas of the Mojave Desert region, that widespread Late Cretaceous cooling results from refrigeration due to subduction of a shallowly dipping Laramide slab or to erosional denudation, and suggest alternatively that post-intrusion cooling and exhumation by extensional structures are recorded. Widespread crustal melting and magmatism followed by extension and cooling in the Late Cretaceous are most consistent with production of a low-viscosity lower crust during anatexis and/or delamination of mantle lithosphere at the onset of Laramide shallow subduction.

  5. The Pinto shear zone; a Laramide synconvergent extensional shear zone in the Mojave Desert region of the southwestern United States

    USGS Publications Warehouse

    Wells, M.L.; Beyene, M.A.; Spell, T.L.; Kula, J.L.; Miller, D.M.; Zanetti, K.A.

    2005-01-01

    The Pinto shear zone is one of several Late Cretaceous shear zones within the eastern fringe of the Mesozoic magmatic arc of the southwest Cordilleran orogen that developed synchronous with continued plate convergence and backarc shortening. We demonstrate an extensional origin for the shear zone by describing the shear-zone geometry and kinematics, hanging wall deformation style, progressive changes in deformation temperature, and differences in hanging wall and footwall thermal histories. Deformation is constrained between ???74 and 68 Ma by 40Ar/39Ar thermochronology of the exhumed footwall, including multi-diffusion domain modeling of K-feldspar. We discount the interpretations, applied in other areas of the Mojave Desert region, that widespread Late Cretaceous cooling results from refrigeration due to subduction of a shallowly dipping Laramide slab or to erosional denudation, and suggest alternatively that post-intrusion cooling and exhumation by extensional structures are recorded. Widespread crustal melting and magmatism followed by extension and cooling in the Late Cretaceous are most consistent with production of a low-viscosity lower crust during anatexis and/or delamination of mantle lithosphere at the onset of Laramide shallow subduction. ?? 2005 Elsevier Ltd. All rights reserved.

  6. Megabreccia deposits in an extensional basin: The Miocene-Pliocene Horse Camp Formation, east-central Nevada

    SciTech Connect

    Schmitt, J.G.; Brown, C.L. )

    1991-06-01

    Three varieties of megabreccia deposits are present in alluvial-lacustrine extensional basin fill of the Miocene-Pliocene Horse Camp Formation of east-central Nevada. Coherent debris sheets (150-300 m thick; up to 1,500 m long) consist of Oligocene-Miocene volcanic rock masses which are internally fractured yet retain their stratigraphic integrity. Fracture zones show variable amounts of displacement (up to 5 cm) and brecciation. These debris sheets overlie horizontally stratified sandstone and laminated claystone interpreted as playa deposits and are overlain by lithified grus. Emplacement of these coherent debris sheets was by landslide or block slide. Associated deposits of large boulders within playa facies suggest gliding of blocks broken from the edges of the landslides across wet playa surfaces. Large (1.6 - 2.4 km-long) allochthonous blocks consist of intact Paleozoic and Tertiary volcanic stratigraphic sequences which are brecciated and attenuated. Brecciation is accompanied in places by incorporation of muddy sand matrix. These blocks may be fragments of the upper plate of low-angle detachment faults which broke away as gravity-driven blocks from the nearby Horse Range and slid along the uplifted former detachment surface into the adjacent Horse Camp basin. Megabreccia deposits characterize Teritary extensional basins in western North America. Detailed analysis of their stratigraphic, sedimentologic, and structural relations can provide a better understanding of the complex tectonosedimentary history of these basins.

  7. Seismic reflection geometry of the Newark basin margin in Eastern Pennsylvania. Evidence for extensional reactivation of Paleozoic thrust faults

    SciTech Connect

    Ratcliffe, N.M.; Burton, W.C.; D'Angelo, R.M.; Costain, J.K.

    1986-07-01

    Low-angle 25/sup 0/ to 35/sup 0/ dips have been determined for the border fault of the Newark basin near Riegelsville, Pennsylvania, based on a VIBROSEIS profile and two continuously-cored drill holes across faults at the basin margin. A group of moderately strong planar reflections in a zone 0.5 km thick in gneiss and carbonate rocks of the footwall block coincide with the updip projection of imbricate fault slices and mylonites associated with the Musconetcong thrust system of Drake and others (1967). Contrasts in acoustic impedance among mylonitic dolostone and mylonitic gneiss and their protoliths, determined from measurements on core samples, are sufficiently large to account for reflections seen in the footwall block. Analysis of drill core and surface outcrops supports the conclusion that low-angle extensional faulting in the Early Mesozoic was localized by reactivation of Paleozoic imbricate thrust faults in the basement rocks. Extension in the NW-SE quadrant was approximately perpendicular to the strike of the ancient thrust faults in Eastern Pennsylvania and a passive origin of the Newark basin here is suggested. The data presented here represent some of the most explicit three-dimensional information obtained thus far, in the Eastern United States, in support of the concept of fault reactivation in controlling formation of Early Mesozoic extensional basins.

  8. Low-angle extensional faulting, reactivated mylonites, and seismic reflection geometry of the Newark basin margin in eastern Pennsylvania

    SciTech Connect

    Ratcliffe, N.M.; Burton, W.C.; D'Angelo, R.M.; Costain, J.K.

    1986-09-01

    Low-angle 25/sup 0/ to 35/sup 0/ dips have been determined for the border fault of the Newark basin near Riegelsville, Pennsylvania, on the basis of a Vibroseis profile and two continuously cored drill holes across faults at the basin margin. A group of moderately strong planar reflections in a zone 0.5 km thick in gneiss and carbonate rocks of the footwall block coincides with the updip projection of imbricate fault slices and mylonites associated with the Musconetcong thrust system of Drake et al. (1967). Contrasts in acoustic impedance among mylonitic dolostone and mylonitic gneiss and their protoliths, determined from measurements on samples from a third cored hole, are sufficiently large to account for reflections seen in the footwall block. Analysis of drill core and surface outcrops supports the conclusion that low-angle extensional faulting in the early Mesozoic was localized by reactivation of Paleozoic imbricate thrust faults in the basement rocks. Extension in the northwest-southeast quadrant was approximately perpendicular to the strike of the ancient thrust faults in eastern Pennsylvania. The data presented here are the most explicit three-dimensional information obtained thus far in the eastern US in support of the concept of fault reactivation in controlling formation of early Mesozoic extensional basins.

  9. Tectonics and metallogenic provinces

    USGS Publications Warehouse

    Guild, P.W.

    1983-01-01

    Various theories have been advanced to explain the well-known uneven distribution of metals and ore-deposit types in space and time. Primordial differences in the mantle, preferential concentration of elements in the crust, the prevalence of ore-forming processes at certain times and (or) places, and combinations of one or several of these factors have all been called upon to account for the "metallogenic provinces," which can be defined loosely as regions containing similar deposits of one or a group of metals or minerals. Because many, perhaps most, provinces have complex, multistage origins, the relative importance of inheritance vs. process is still controversial. In recent years the geographic relationship of many geologically young provinces to present-day plate-tectonic positions (accreting or consuming margins, intraplate structures, etc.) has been widely recognized, and the presumption is strong that older provinces had similar relationships to former plates. As most ore deposits resulted from a favorable conjunction of geological processes that are no longer operative, elucidation of their genesis requires reconstruction of the geologic history of the province, with particular emphasis on events coeval with mineralization. Tectonic analysis is an important aspect of this reconstruction; data from orbiting satellites have contributed greatly to this analysis, as the voluminous literature of the past decade testifies. Both the synoptic view of large areas and the ability to emphasize faint contrasts have revealed linear, curvilinear, and circular features not previously recognized from field studies. Some of these undoubtedly reflect basement structures that have contributed to the development, or limit the extent, of metallogenic provinces. Their recognition and delineation will be increasingly valuable to the assessment of resources available and as guides to exploration for the ores needed by future generations. ?? 1983.

  10. The North Cycladic Detachment System and associated mineralization, Mykonos, Greece: insights on the evolution of stress regime in the Aegean domain

    NASA Astrophysics Data System (ADS)

    Menant, A.; Jolivet, L.; Augier, R.; Skarpelis, N.

    2012-04-01

    In the Aegean back-arc domain, some 30-35 Ma ago, the increasing rate of slab retreat led to the initiation of post-orogenic extension, largely accommodated by several large-scale structures such as the North Cycladic Detachment System (NCDS). Although the Aegean N-S extension is still active nowadays, particularly with the Evia and Corinth rifts, an E-W compressional regime developed 5-6 Ma ago with the propagation of the North Anatolian Fault and its extension within the Central Hellenic Shear Zone. On Mykonos island (Cyclades), the NE-SW back-arc extension is well expressed, particularly with two main shallow-dipping shear zones belonging to the NCDS: the Livada and Mykonos detachments associated with NW-SE banded barite and Fe-hydroxide vertical veins emplaced from 10-11 Ma. A structural study of detachments, veins and faults show an evolution of the kinematics of these tectonic structures. We show that (1) most of the displacement was first accommodated by the shallow-dipping Livada and Mykonos detachments with a N30°E direction of extension. Minor steep and shallow-dipping normal faults formed during this episode above and below the detachment and some of them were mineralized. (2) The normal faults and the veins were later reworked in a strike-slip regime with an E-W direction of compression and a persistent N-S to NE-SW extension. Alternating periods of extension with the same direction of the least principal stress are recorded during this stage. (3) The last stage is compressional with a minor reworking of shallow-dipping faults (locally including the detachment itself) with an E-W compression. We interpret this increase of the E-W compressional component during the activity of the detachments and the emplacement of ore deposits as a consequence of the initiation of the westward motion of Anatolia that we date at ~10 Ma, some 5 Ma before the propagation of the North Anatolian Fault and the localization of the strain on the margins of the Aegean Sea.

  11. Scenario based tsunami wave height estimation towards hazard evaluation for the Hellenic coastline and examples of extreme inundation zones in South Aegean

    NASA Astrophysics Data System (ADS)

    Melis, Nikolaos S.; Barberopoulou, Aggeliki; Frentzos, Elias; Krassanakis, Vassilios

    2016-04-01

    A scenario based methodology for tsunami hazard assessment is used, by incorporating earthquake sources with the potential to produce extreme tsunamis (measured through their capacity to cause maximum wave height and inundation extent). In the present study we follow a two phase approach. In the first phase, existing earthquake hazard zoning in the greater Aegean region is used to derive representative maximum expected earthquake magnitude events, with realistic seismotectonic source characteristics, and of greatest tsunamigenic potential within each zone. By stacking the scenario produced maximum wave heights a global maximum map is constructed for the entire Hellenic coastline, corresponding to all expected extreme offshore earthquake sources. Further evaluation of the produced coastline categories based on the maximum expected wave heights emphasizes the tsunami hazard in selected coastal zones with important functions (i.e. touristic crowded zones, industrial zones, airports, power plants etc). Owing to its proximity to the Hellenic Arc, many urban centres and being a popular tourist destination, Crete Island and the South Aegean region are given a top priority to define extreme inundation zoning. In the second phase, a set of four large coastal cities (Kalamata, Chania, Heraklion and Rethymno), important for tsunami hazard, due i.e. to the crowded beaches during the summer season or industrial facilities, are explored towards preparedness and resilience for tsunami hazard in Greece. To simulate tsunamis in the Aegean region (generation, propagation and runup) the MOST - ComMIT NOAA code was used. High resolution DEMs for bathymetry and topography were joined via an interface, specifically developed for the inundation maps in this study and with similar products in mind. For the examples explored in the present study, we used 5m resolution for the topography and 30m resolution for the bathymetry, respectively. Although this study can be considered as

  12. Seismicity and active tectonics at Coloumbo Reef (Aegean Sea, Greece): Monitoring an active volcano at Santorini Volcanic Center using a temporary seismic network

    NASA Astrophysics Data System (ADS)

    Dimitriadis, I.; Karagianni, E.; Panagiotopoulos, D.; Papazachos, C.; Hatzidimitriou, P.; Bohnhoff, M.; Rische, M.; Meier, T.

    2009-02-01

    The volcanic center of Santorini Island is the most active volcano of the southern Aegean volcanic arc. Α dense seismic array consisting of fourteen portable broadband seismological stations has been deployed in order to monitor and study the seismo-volcanic activity at the broader area of the Santorini volcanic center between March 2003 and September 2003. Additional recordings from a neighbouring larger scale temporary network (CYCNET) were also used for the relocation of more than 240 earthquakes recorded by both arrays. A double-difference relocation technique was used, in order to obtain optimal focal parameters for the best-constrained earthquakes. The results indicate that the seismic activity of the Santorini volcanic center is strongly associated with the tectonic regime of the broader Southern Aegean Sea area as well as with the volcanic processes. The main cluster of the epicenters is located at the Coloumbo Reef, a submarine volcano of the volcanic system of Santorini Islands. A smaller cluster of events is located near the Anydros Islet, aligned in a NE-SW direction, running almost along the main tectonic feature of the area under study, the Santorini-Amorgos Fault Zone. In contrast, the main Santorini Island caldera is characterized by the almost complete absence of seismicity. This contrast is in very good agreement with recent volcanological and marine studies, with the Coloumbo volcanic center showing an intense high-temperature hydrothermal activity, in comparison to the corresponding low-level activity of the Santorini caldera. The high-resolution hypocentral relocations present a clear view of the volcanic submarine structure at the Coloumbo Reef, showing that the main seismic activity is located within a very narrow vertical column, mainly at depths between 6 and 9 km. The focal mechanisms of the best-located events show that the cluster at the Coloumbo Reef is associated with the "Kameni-Coloumbo Fracture Zone", which corresponds to the

  13. Using Facilities And Potential Of Geothermal Resources In The Canakkale Province - NW Turkey

    NASA Astrophysics Data System (ADS)

    Deniz, Ozan; Acar Deniz, Zahide

    2016-04-01

    Turkey, due to its geological location, has a rich potential in point of geothermal resources. Çanakkale province is located northwestern (NW) part of Turkey and it has important geothermal fields in terms of geothermal energy potential. Geothermal resources reach to the surface both effects of past volcanic activity and extensions of fault zones associated with complex tectonic systems in the region. The aim of this study is to summarize hydrogeochemical characteristics, using facilities and potential of hot springs and spas located in the Çanakkale province. There are 13 geothermal fields in the region and the surface temperatures of hot springs are ranging between 28 centigrade degree and 175 centigrade degree. Hydrogeochemical compositions of thermal water display variable chemical compositions. Na, Ca, SO4, HCO3 and Cl are the dominant ions in these waters. Thermal waters of Tuzla and Kestanbol geothermal fields which is located the near coastal area can be noted NaCl type. Because these two geothermal waters have high TDS values, scaling problems are seen around the hot springs and pipelines. Geothermal waters in the province are meteoric origin according to oxygen-18, deuterium and tritium isotopes data. Long underground residence times of these waters and its temperatures have caused both more water - rock interaction and low tritium values. Geothermal energy is utilized in many areas in Turkey today. It is generally used for space heating, balneotherapy and electricity generation. Explorations of geothermal resources and investments in geothermal energy sector have risen rapidly in the recent years particularly in western Turkey. High-temperature geothermal fields are generally located in this region related to the Aegean Graben System and the North Anotalian Fault Zone. All geothermal power plants in Turkey are located in this region. Considering the Çanakkale province, most geothermal fields are suitable for multipurpose usage but many of them have

  14. A new metamorphic map of Syros Island (Aegean Sea, Greece): implications for strain localization from prograde to retrograde path

    NASA Astrophysics Data System (ADS)

    Laurent, Valentin; Jolivet, Laurent; Roche, Vincent; Augier, Romain; Scaillet, Stéphane; Cardello, Luca

    2015-04-01

    The Aegean domain is located in the eastern part of the Mediterranean and has undergone a complex Alpine history that can be summarized in two successive episodes: (1) The formation of the Hellenides-Taurides belt due to the convergence between Eurasia and Africa; during this episode, a series of oceanic and continental nappes entered the subduction zone and were thrust on top of each other in a HP-LT metamorphic context. (2) From 35-30 Ma, an acceleration of slab retreat led to the collapse of the belt and the formation of large detachments. The island of Syros (Cycladic Blueschists belt) is worldwide known for the excellent preservation of HP-LT tectonic and metamorphic features associated with these processes, possibly providing one of the best places to study the deformation and metamorphic evolution of the subduction interface. Syros has recorded a complex deformation history during both the prograde and retrograde phase that resulted in the juxtaposition of two main units: (1) the Cycladic Blueschists Unit (CBU), and (2) the Vari unit cropping out in the SE of the island. Conflicting tectonic interpretations have been proposed to explain the evolution of the island, in part reflecting the lack of consensus about the detailed tectonic structure of the CBU. A new geological and metamorphic map of Syros is proposed to better characterize the different structures related to prograde and/or retrograde deformation stages. High-resolution field-mapping, combined with detailed structural-petrological observations, allows us to subdivide the CBU into three sub-units separated by major ductile shear zones. From top to bottom, these are: 1) the Kampos, 2) the Chroussa, and 3) the Posidonia units. Each of these units experienced similar peak eclogite-facies conditions (ca. 20 kbar - 550 °C), variably overprinted under blueschist- and greenschist-facies conditions across the nappe pile. New ductile structures have been discovered. Among those, a new large-scale top

  15. April 16, 2015 Crete Island Earthquake (Mw=5.9) Series and its Seismotectonic Significance, Southern Aegean Sea

    NASA Astrophysics Data System (ADS)

    Yalçın, Hilal; Kürçer, Akın; Gülen, Levent

    2016-04-01

    The active deformation of the southern Aegean Sea is a result of the northward motion of the African and Arabian Plates with respect to the Eurasian Plate in the Eastern Mediterranean Region. The Hellenic subduction zone plays a key role in the active tectonics of the region. On 16 April, 2015, a moderate earthquake occurred on the eastern part of Hellenic arc (south of Crete island), with a moment magnitude of Mw=5.9. A series of aftershocks were occurred within four months following the mainshock, which have magnitudes varying from Mw = 3.4 to 5.4. Source parameters of the 16 April 2015 earthquake have been modeled in order to reveal the regional stress tensor and the tectonic style of the region. In this study, the source parameters of the main shock and 36 aftershocks that have magnitudes M≥3.4 have been determined and modeled by seismic moment tensor waveform inversion method developed by Sokos and Zahradnik (2006) algorithm using the near-field and regional waveforms. The depth of earthquakes are varied from 2 to 61 km. Stress tensor can describe reliably principle stress axes (σ1, σ2, σ3), their relative size and stress field variations. Stress tensor inversions have been carried out using the Micheal method (1984, 1987). In this study, 16 April 2015 Crete Earthquake mainshock (Mw=5.9), a total of 36 earthquake moment tensor solutions that belong to the Crete earthquake sequence and 24 earthquake moment tensor solutions of previous main shocks in the region have been compiled and used in the stress inversion calculation. Orientations of σ1, σ2 and σ3 were computed and the principal directions are projected onto a lower hemisphere Wulff net. The best fit was attained for Phi = 0.38+/-0.13609 and indicated that the stress regime revealed strike-slip faulting with reverse component and for the azimuth and plunge pair of (-161.6°, 21.7°) for σ1, (-11.1°, 65.4°) for σ2 and (103.8°, 10.9°) for σ3. At the final step of the study, Gutenberg and

  16. Levels of (210)Po in some commercial fish species consumed in the Aegean Sea coast of Turkey and the related dose assessment to the coastal population.

    PubMed

    Aközcan, S

    2013-04-01

    Concentrations of (210)Po were determined in the edible muscle tissue of five species of marine fish: Sardine (Sardine plichardus) and Anchovy (Engraulis encrasicolus), Red mullet (Mullus barbatus), Horse mackerel (Trachurus trachurus) and Gilt-head sea bream (Sparus aurata) collected from five stations in the Aegean Sea Region of Turkey during the fishery season 2010. The (210)Po concentrations in the fish samples were found to vary from not detected levels to 389 ± 45 Bq kg(-1) dry wt. These variations in (210)Po content in different species are probably due to differences in metabolism and feeding patterns. The highest levels for (210)Po were observed in Anchovy (E. encrasicolus) species.

  17. Recurrent intrusions of transitional waters of Eastern Mediterranean origin in the Cretan Sea as a tracer of Aegean Sea dense water formation events

    NASA Astrophysics Data System (ADS)

    Velaoras, Dimitris; Krokos, George; Theocharis, Alexander

    2015-06-01

    Available temperature and salinity data in the Cretan Sea from 1955 up to 2014 as well as literature sources were revisited in order to trace the appearance of low salinity, temperature, oxygen and nutrient-rich waters inside the basin at depths below the intermediate layer. First appearing as far back as 1961 in literature, these waters were found originating in the layers that separate intermediate and deep waters of the Eastern Mediterranean Sea (EMed) and were named Transitional Mediterranean Water (TMW) in the 1990s. Data analysis showed that the appearance of TMW in the Cretan Sea is a recurrent phenomenon connected to water mass exchanges between the Aegean Sea and the EMed. In particular, the inflow of TMW in the Cretan basin acts as compensation for the outflow of equally dense or denser masses from the Aegean. This export is a result of dense water formation (DWF) events taking place inside the Aegean Sea triggering TMW compensatory inflow into the Cretan Sea through the Cretan Straits. In this context, TMW intrusions in the Cretan basin can be used as a tracer of DWF in the Aegean Sea while the depth of the intrusion can provide valuable information about the intensity of the DWF event. The importance of TMW intrusions is not solely restricted to the tracing and evaluation of DWF events but could additionally expand to the impact on local ecological processes as TMW is a nutrient carrier for the oligotrophic Cretan Sea. It is obvious that this low salinity, temperature and oxygen layer is what was later named TMW. The core temperature, salinity and oxygen values reported by Miller (1974) fall within the range of values observed during the PELAGOS project in 1994, as noted in Section 'Presence of low salinity water masses below the intermediate layer in the Cretan Sea during the EMT event'. Using the same dataset provided by MEDATLAS 2002 database, a salinity transect along the Cretan Sea is reconstructed in Fig. 5. The bottle data originate from the

  18. Eastern-Mediterranean ventilation variability during sapropel S1 formation, evaluated at two sites influenced by deep-water formation from Adriatic and Aegean Seas

    NASA Astrophysics Data System (ADS)

    Filippidi, A.; Triantaphyllou, M. V.; De Lange, G. J.

    2016-07-01

    Present-day bottom-water ventilation in the Eastern Mediterranean basin occurs through deep-water convection originating from the two marginal basins, i.e. Adriatic and Aegean Seas. In the paleo record, long periods of enhanced deep-water formation have been alternating with shorter periods of reduced deep-water formation. The latter is related mainly to low-latitude humid climate conditions and the enhanced deposition and preservation of organic-rich sediment units (sapropels). This study focuses on sedimentary archives of the most-recent sapropel S1, retrieved from two sites under the direct influence of the two deep-water formation areas. Restricted oxygen conditions have developed rapidly at the beginning of S1 deposition in the Adriatic site, but bottom-water conditions have not persistently remained anoxic during the full interval of sapropel deposition. In fact, the variability in intensity and persistence of sedimentary redox conditions at the two deep-water formation sites is shown to be related to brief episodes of climate cooling. In the Adriatic site, sapropel deposition appears to have been interrupted twice. The 8.2 ka event, only recovered at the Adria site, is characterized by gradually increasing suboxic to possibly intermittently oxic conditions and decreasing Corg fluxes, followed by an abrupt re-establishment of anoxic conditions. Another important event that disrupted sapropel S1 formation, has taken place at ca. 7.4 cal ka BP. The latter event has been recovered at both sites. In the Adriatic site it is followed by a period of sedimentary conditions that gradually change from suboxic to more permanently oxic, as deduced from the Mn/Al pattern. Using the same proxy for suboxic/oxic sedimentary redox conditions, we observe that conditions in the Aegean Sea site shift to more permanently oxic from the 7.4 ka event onwards. However, at both sites the accumulation and preservation of enhanced amounts of organic matter have continued under these

  19. Multi-Biomarker Responses After Exposure to Pollution in the Mediterranean Mussels (Mytilus galloprovincialis L.) in the Aegean Coast of Turkey.

    PubMed

    Ozkan, Dilara; Dagdeviren, Melih; Katalay, Selma; Guner, Adem; Yavaşoğlu, N Ülkü Karabay

    2017-01-01

    In this study, sublethal effects on the Mediterranean mussels (Mytilus galloprovincialis L.) collected from the Aegean coast of Turkey were determined. Enzymes such as glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and acetylcholinesterase (AChE), metallothionein (MT) mRNA expressions, thiobarbituric acid reactive substances (TBARS) contents, determination of 14 heavy metals and micronucleus frequency were selected as multibiomarkers. Results show that heavy metals and an increase in the level of MT gene expression have been determined in tissues of mussels collected from all stations. The GST, SOD and CAT enzymes were increased in mussels of Aliaga and Old Foca, compared to the mussels of Urla, while it was showed inhibition at AChE levels. Extensive LP is determined on mussels of Aliaga. It was determined that mussels in Aliaga region have exposed more oxidative stress than Old Foca and Urla. These biomarkers were carried out for the first time in these stations to assess environmental quality.

  20. Re-examination of models for the origin of granite-rhyolite provinces in the midcontinent region, USA

    SciTech Connect

    Van Schmus, W.R. . Dept. of Geology)

    1993-03-01

    New isotopic data for the 1.47 Ga Eastern Granite-Rhyolite Province and the 1.37 Ga Southern Granite-Rhyolite Province require re-examination of models for the origin of these suites of rock. For the most part, eNd(t) values for the granite-rhyolite provinces and A-type plutons intrusive into adjacent Early proterozoic basement are compatible with origin through melting of 1.8 Ga continental crust. However, new data shows that southeastern parts of the granite-rhyolite provinces yield positive [var epsilon]Nd(t) data is an E-W trending belt of intermediate values in northern Oklahoma; [var epsilon]Nd(t) data south of this belt, in s. Oklahoma, are equivalent to that in Kansas and Nebraska, reflecting cal 1.8 Ga lower crust. The granite-rhyolite provinces are not related to any well defined tectonic event, and they have commonly been referred to as anorogenic. The thermal event responsible for producing the silicic melts may have been associated with an extensional regime, in view of the a-type character of the granites.

  1. Extensional deformation of the Guadalquivir Basin: rate of WSW-ward tectonic displacement from Upper Tortonian sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco J.; Azañón, Jose Miguel; Rodríguez-Fernández, Jose; María Mateos, Rosa

    2016-04-01

    The Guadalquivir Basin (Upper Tortonian-Quaternary sedimentary infilling) has been considered the foreland basin of the Betic Orogen built up during its collision with the Sudiberian margin. The basin is currently restricted to its westernmost sector, in the Cadiz Gulf, because the Neogene-Quaternary uplift of the Betic Cordillera has produced the emersion of their central and eastern parts. The upper Tortonian chronostratigraphic unit is the oldest one and it was indistinctly deposited on the South Iberian paleomargin and the External units from the Betic Cordillera. However, these rocks are undeformed on the Sudiberian paleomargin while they are deeply affected by brittle deformation on the External Betic Zone. Outcrops of Upper Tortonian sedimentary rocks on External Betic Zone are severely fragmented showing allocthonous characters with regard to those located on the Sudiberian paleomargin. This post- Upper Tortonian deformation is not well known in the External Zones of the Cordillera where the most prominent feature is the ubiquity of a highly deformed tecto-sedimentary unit outcropping at the basement of the Guadalquivir sedimentary infilling. This tecto-sedimentary unit belongs to the Mass Wasting Extensional Complex (Rodríguez-Fernández, 2014) formed during the collision and westward migration of the Internal Zone of the Betic Cordillera (15-8,5 Ma). In the present work, we show an ensemble of tectonic, geophysical and cartographic data in order to characterize the post-Upper Tortonian deformation. For this, seismic reflection profiles have been interpreted with the help of hidrocarbon boreholes to define the thickness of the Upper Tortonian sedimentary sequence. All these data provide an estimation of the geometrical and kinematic characteristics of the extensional faults, direction of movement and rate of displacement of these rocks during Messinian/Pliocene times. References Rodríguez-Fernández, J., Roldan, F. J., J.M. Azañón y Garcia-Cortes, A

  2. Evolution of Extensional Structures Within the Internal Parts of the Higher Himalaya (Sutlej River Region, NW India)

    NASA Astrophysics Data System (ADS)

    Hintersberger, E.; Thiede, R. C.; Strecker, M. R.

    2006-12-01

    One of the most challenging problems in understanding the tectonics of active mountain belts is the presence of normal faults in the overall compressive settings. Consistent observations in the Andes, the Alps, as well as in the Himalaya record the presence of upper crustal structures with normal displacement contemporaneously with shortening and thrusting at lower crustal levels and elevations. Within the internal and high elevation sectors of the Himalayan orogen, active N-S striking normal fault systems are well documented. Crosscutting relationships indicate that these closely spaced faults cut all pre-existing compressional structures and are the youngest structural features in this region. However, their mode of propagation in time and space, as well as their origin remain largely unknown. For example, in the Sutlej River region (NW Himalaya, India), it is unclear whether these fault systems either are a local phenomenon and related to ongoing exhumation of the Leo Pargil metamorphic dome or, alternatively, are an integral part of the structural framework in the Himalaya and thus of regional importance. To better understand which processes constrain N-S striking normal faulting in the evolution of the Higher Himalaya, we have mapped the young extensional sectors in the greater Sutlej River area. In addition, we combine seismological data with the spacial and temporal distribution of brittle normal faulting to better understand the interaction between the ongoing normal and thrust faulting in the orogen. Using globally recorded seismicity data we observed ongoing extension in a N-S striking band extending from to the Leo Pargil extensional dome southward to the main thrust belts along the Himalayan front. Further installation of a seismic network in this region will provide the level of resolution needed to analyze the detailed pattern of local seismicity of the Sutlej-Spiti River region. Our preliminary structural geological field work reveals that the

  3. Uniaxial Extensional Behavior of A--B--A Thermoplastic Elastomers: Structure-Properties Relationship and Modeling

    NASA Astrophysics Data System (ADS)

    Martinetti, Luca

    At service temperatures, A--B--A thermoplastic elastomers (TPEs) behave similarly to filled (and often entangled) B-rich rubbers since B block ends are anchored on rigid A domains. Therefore, their viscoelastic behavior is largely dictated by chain mobility of the B block rather than by microstructural order. Relating the small- and large-strain response of undiluted A--B--A triblocks to molecular parameters is a prerequisite for designing associated TPE-based systems that can meet the desired linear and nonlinear rheological criteria. This dissertation was aimed at connecting the chemical and topological structure of A--B--A TPEs with their viscoelastic properties, both in the linear and in the nonlinear regime. Since extensional deformations are relevant for the processing and often the end-use applications of thermoplastic elastomers, the behavior was investigated predominantly in uniaxial extension. The unperturbed size of polymer coils is one of the most fundamental properties in polymer physics, affecting both the thermodynamics of macromolecules and their viscoelastic properties. Literature results on poly(D,L-lactide) (PLA) unperturbed chain dimensions, plateau modulus, and critical molar mass for entanglement effect in viscosity were reviewed and discussed in the framework of the coil packing model. Self-consistency between experimental estimates of melt chain dimensions and viscoelastic properties was discussed, and the scaling behaviors predicted by the coil packing model were identified. Contrary to the widespread belief that amorphous polylactide must be intrinsically stiff, the coil packing model and accurate experimental measurements undoubtedly support the flexible nature of PLA. The apparent brittleness of PLA in mechanical testing was attributed to a potentially severe physical aging occurring at room temperature and to the limited extensibility of the PLA tube statistical segment. The linear viscoelastic response of A--B--A TPEs was first

  4. Isotope geochemistry of recent magmatism in the Aegean arc: Sr, Nd, Hf, and O isotopic ratios in the lavas of Milos and Santorini-geodynamic implications

    USGS Publications Warehouse

    Briqueu, L.; Javoy, M.; Lancelot, J.R.; Tatsumoto, M.

    1986-01-01

    In this comparative study of variations in the isotopic compositions (Sr, Nd, O and Hf) of the calc-alkaline magmas of the largest two volcanoes, Milos and Santorini, of the Aegean arc (eastern Mediterranean) we demonstrate the complexity of the processes governing the evolution of the magmas on the scale both of the arc and of each volcano. On Santorini, the crustal contamination processes have been limited, effecting the magma gradually during its differentiation. The most differentiated lavas (rhyodacite and pumice) are also the most contaminated. On Milos, by contrast, these processes are very extensive. They are expressed in the 143Nd/144Nd vs. 87Sr/86Sr diagram as a continuous mixing curve between a mantle and a crustal end member pole defined by schists and metavolcanic rocks outcropping on these volcanoes. In contrast with Santorini, the least differentiated lavas on Milos are the most contaminated. These isotopic singularities can be correlated with the geodynamic evolution of the Aegean subduction zone, consisting of alternating tectonic phases of distension and compression. The genesis of rhyolitic magmas can be linked to the two phases of distension, and the contamination of the calc-alkaline mantle-derived magmas with the intermediate compressive phase. The isotopic characteristics of uncontaminated calc-alkaline primitive magmas of Milos and Santorini are directly comparable to those of magmas generated in subduction zones for which a contribution of subducted sediments to partial melts from the mantle is suggested, such as in the Aleutian, Sunda, and lesser Antilles island arcs. However, in spite of the importance of the sediment pile in the eastern Mediterranen oceanic crust (6-10 km), the contribution of the subducted terrigenous materials remains of limited amplitude. ?? 1986.

  5. Geochemistry of mylonitic gneisses from the Cycladic Basement Unit (Paros and Serifos, Aegean Sea): implications for protoliths of the high-grade gneisses

    NASA Astrophysics Data System (ADS)

    McGrath, Annette; Stouraiti, Christina; Windley, Brian

    2016-10-01

    The nature of the protolith(s) of high-grade gneisses from the Aegean Cycladic Basement Unit of the islands of Paros and Serifos is investigated using whole-rock geochemistry and Sr-Nd-O isotopes, in order to better understand their origin and to compare with possible equivalents from the southern Aegean region. On Paros, the basement unit consists of heterogeneous, mylonitized upper amphibolite-grade paragneisses and associated migmatitic rocks, whereas on Serifos, it consists of a mylonitized felsic gneiss, intercalated with layers and lenses of S-type leucogranites and minor mafic metavolcanics. New Nd, Sr and O isotope data suggest a predominantly crustal-derived source in the gneiss protolith from both islands: high initial 87Sr/86Sr ratios (≥7052 to 0.711, calculated at 300 Ma), negative initial ɛNd (-2.8 to -7.7) values for bulk-rock gneiss samples, and high δ18O values of quartz separates (+10 to +12.7 ‰). Major and trace-element variations corroborate that chemical differentiation within the NW Paros gneiss subunit results from progressive migmatitization. Peraluminous gneisses from eastern Paros share clear similarities with metapelitic gneisses from the Naxos gneiss dome, in terms of their trace-element patterns, ɛNd (300) and O isotope characteristics. The mineral assemblage, the fine grain size (due to intense mylonitization), and the metaluminous affinity of the South Serifos grey quartzofeldpathic gneiss do not allow for an unambiguous interpretation for these undated rocks; however, a combination of geochemical parameters and tectonic discrimination diagrams indicates an immature siliciclastic (greywacke) protolith from a continental island arc setting. Sr-Nd isotopic systematics indicates an increasing lower crustal component in gneisses from NW Paros, which is closer to the migmatitic core of the Paros dome. The overall isotopic trend of the gneissic Cycladic Basement Unit on Paros is spatially correlated with that of the Naxos gneiss dome.

  6. Investigation of heavy metal pollution in eastern Aegean Sea coastal waters by using Cystoseira barbata, Patella caerulea, and Liza aurata as biological indicators.

    PubMed

    Aydın-Önen, S; Öztürk, M

    2017-01-19

    In order to have an extensive contamination profile of heavy metal levels (Cd, Cu, Fe, Mn, Ni, Pb, and Zn), seawater, sediment, Patella caerulea, Cystoseira barbata, and Liza aurata were investigated by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Samples were collected from five coastal stations along the eastern Aegean Sea coast (Turkey) on a monthly basis from July 2002 through May 2003. According to the results of this study, heavy metal levels were arranged in the following sequence: Fe > Pb > Zn > Mn > Ni > Cu > Cd for water, Fe > Cu > Mn > Ni > Zn > Pb > Cd for sediment, Fe > Zn > Mn > Pb > Ni > Cd > Cu for C. barbata, Fe > Zn > Mn > Ni > Pb > Cu > Cd for P. caerulea, and Fe > Zn > Mn > Cu > Ni > Pb > Cd for L. aurata. Moreover, positive relationships between Fe in water and Mn in water, Fe in sediment and Mn in sediment, Fe in C. barbata and Mn in C. barbata, Fe in P. caerulea and Mn in P. caerulea, and Fe in L. aurata and Mn in L. aurata may suggest that these metals could be originated from the same anthropogenic source. C. barbata represented with higher bioconcentration factor (BCF) values, especially for Fe, Mn, and Zn values. This observation may support that C. barbata can be used as an indicator species for the determinations of Fe, Mn, and Zn levels. Regarding Turkish Food Codex Regulation's residue limits, metal values in L. aurata were found to be lower than the maximum permissible levels issued by Turkish legislation and also the recommended limits set by FAO/WHO guidelines. The results of the investigation indicated that P. caerulea, L. aurata, and especially C. barbata are quantitative water-quality bioindicators and biomonitoring subjects for biologically available metal accumulation for Aegean Sea coastal waters.

  7. Molecular Basis of β-Thalassemia in the Population of the Aegean Region of Turkey: Identification of A Novel Deletion Mutation.

    PubMed

    Ozkinay, Ferda; Onay, Huseyin; Karaca, Emin; Arslan, Esra; Erturk, Biray; Ece Solmaz, Asli; Tekin, Ismihan Merve; Cogulu, Ozgur; Aydinok, Yeşim; Vergin, Canan

    2015-01-01

    β-Thalassemia (β-thal) is the most common monogenic disorder in Turkey. The aim of this study was to investigate the spectrum of β-thal mutations in the Aegean region of Turkey. The data was derived from 1171 unrelated β-thal subjects, detected in a regional reference hospital between November 2004 and December 2013. Screening for the 22 common mutations was performed using the polymerase chain reaction (PCR)-reverse dot-blot method, and direct automated DNA sequencing for the unknown samples. Thirty-one different β-thal alleles were identified. Seven mutations, namely IVS-I-110 (G > A) (41.7%), IVS-I-1 (G > A) (8.9%), IVS-II-745 (C > G) (8.6%), codon 8 (-AA) (7.7%), IVS-II-1 (G > A) (7.2%), IVS-I-6 (T > C) (6.6%), codon 39 (C > T) (4.6%) accounted for 85.3% of the mutated alleles. Frequencies of the remaining 24 β-thal mutations were less than 2.2%; these included one novel mutation [HBB: c.206_212del (p.Leu69Profs*19)], and four others [-56 (G > C), codon 16 (-C), IVS-I (-3) (C > T) (codon 29), codon 76 (-C)] found in Turkey for the first time. The results will help to prevent severe β-thal through genetic counseling and prenatal diagnosis (PND) in the Aegean region of Turkey.

  8. Geologic provinces of Oklahoma

    SciTech Connect

    Northcutt, R.A.; Campbell, J.A.

    1995-09-01

    The geologic provinces of Oklahoma are mainly the product of tectonics and attendant sedimentation of Pennsylvanian age. Most boundaries are structural; thus, the provinces map is a generalized tectonic map. Permian and post-Paleozoic strata tend to mask those structures, but most of those strata have been removed by erosion, except in the Anadarko Basin and the Wichita Uplift provinces. The location of most of Oklahoma`s oil and gas resources are either influenced by, or are the direct result of Pennsylvanian tectonics and sedimentation patterns. Therefore, the present study also defines provinces in the subsurface on the basis of geological criteria. The authors have attempted to use the originally published names for the recognized provinces. However, we have also used the most geologically correct names, i.e., Nemaha Uplift, Nemaha Fault Zone, and Central Oklahoma Fault, in lieu of Nemaha {open_quotes}Ridge.{close_quotes} Oklahoma is separated into five major uplifts and five major basins. The Gulf Coastal Plain is not included in this study because it is a veneer of Cretaceous cover that masks significant structures. Faults are the most common boundary element. Although their precise age commonly is known only approximately, their geographic location is less controversial, except in detail. Stratigraphic/structural boundaries are based on less precise geological information. The major example of a surface stratigraphic/structural boundary is the southwestern limit of the Ozark Uplift in eastern Oklahoma. Stratigraphic/structural boundaries in the subsurface are commonly based on structural or isopachous contours from well or geophysical data, or on a structural trend, as well as the experience of the authors. Basement structure is preferred. An example is the boundary that separates the Marietta Basin from adjacent geologic elements.

  9. Use of Landsat Thematic Mapper images in regional correlation of syntectonic strata, Colorado river extensional corridor, California and Arizona

    NASA Technical Reports Server (NTRS)

    Beratan, K. K.; Blom, R. G.; Crippen, R. E.; Nielson, J. E.

    1990-01-01

    Enhanced Landsat TM images were used in conjunction with field work to investigate the regional correlation of Miocene rocks in the Colorado River extensional corridor of California and Arizona. Based on field investigations, four sequences of sedimentary and volcanic strata could be recognized in the Mohave Mountains (Arizona) and the eastern Whipple Mountains (California), which display significantly different relative volumes and organization of lithologies. The four sequences were also found to have distinctive appearances on the TM image. The recognition criteria derived from field mapping and image interpretation in the Mohave Mountains and Whipple Mountains were applied to an adjacent area in which stratigraphic affinities were less well known. The results of subsequent field work confirmed the stratigraphic and structural relations suggested by the Tm image analysis.

  10. Electrospinning of polyvinylidene difluoride with carbon nanotubes: synergistic effects of extensional force and interfacial interaction on crystalline structures.

    PubMed

    Huang, Shu; Yee, Wu Aik; Tjiu, Wuiwui Chauhari; Liu, Ye; Kotaki, Masaya; Boey, Yin Chiang Freddy; Ma, Jan; Liu, Tianxi; Lu, Xuehong

    2008-12-02

    Polyvinylidene difluoride (PVDF) solutions containing a very low concentration of single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) of similar surface chemistry, respectively, were electrospun, and the nanofibers formed were collected using a modified rotating disk collector. The polymorphic behavior and crystal orientation of the nanofibers were studied using wide-angle X-ray diffraction and infrared spectroscopy, while the nanotube alignment and interfacial interactions in the nanofibers were probed by transmission electron microscopy and Raman spectroscopy. It is shown that the interfacial interaction between the SWCNTs and PVDF and the extensional force experienced by the nanofibers in the electrospinning and collection processes can work synergistically to induce highly oriented beta-form crystallites extensively. In contrast, the MWCNTs could not be well aligned along the nanofiber axis, which leads to a lower degree of crystal orientation.

  11. Structural analysis of three extensional detachment faults with data from the 2000 Space-Shuttle Radar Topography Mission

    USGS Publications Warehouse

    Spencer, J.E.

    2010-01-01

    The Space-Shuttle Radar Topography Mission provided geologists with a detailed digital elevation model of most of Earth's land surface. This new database is used here for structural analysis of grooved surfaces interpreted to be the exhumed footwalls of three active or recently active extensional detachment faults. Exhumed fault footwalls, each with an areal extent of one hundred to several hundred square kilometers, make up much of Dayman dome in eastern Papua New Guinea, the western Gurla Mandhata massif in the central Himalaya, and the northern Tokorondo Mountains in central Sulawesi, Indonesia. Footwall curvature in profile varies from planar to slightly convex upward at Gurla Mandhata to strongly convex upward at northwestern Dayman dome. Fault curvature decreases away from the trace of the bounding detachment fault in western Dayman dome and in the Tokorondo massif, suggesting footwall flattening (reduction in curvature) following exhumation. Grooves of highly variable wavelength and amplitude reveal extension direction, although structural processes of groove genesis may be diverse.

  12. Design and fabrication of a length-extensional mode rectangular X-cut quartz resonator with zero temperature coefficient.

    PubMed

    Yokoyama, Yukio; Kawashima, Hirofumi; Kanie, Hisashi

    2006-05-01

    Rectangular X-cut quartz crystal resonators with cut angles theta > 5.0 degrees and aspect ratios Rzy (= width 2z0/length 2y0) from 0.3 to 0.5 are investigated. The resonators oscillate mode is a length-extensional mode. A semiempirical frequency equation was derived from the stress expressed in terms of the trigonometric and the hyperbolic transcendental functions with constants estimated by the regression curve fit to the stress simulated by the finite-element method (FEM). Contours on which a point satisfies a zero first order temperature coefficient condition are shown in a cut angle theta and Rzy diagram. We proved that a fabricated resonator with Rzy = 0.400 and theta = 16.0 degrees, whose design parameter is located in the area of the contour, had a zero temperature coefficient.

  13. The effect of shear and extensional viscosities on atomization of Newtonian and non-Newtonian fluids in ultrasonic inhaler.

    PubMed

    Broniarz-Press, L; Sosnowski, T R; Matuszak, M; Ochowiak, M; Jabłczyńska, K

    2015-05-15

    The paper contains results of the experimental study on atomization process of aqueous solutions of glycerol and aqueous solutions of glycerol-polyacrylamide (Rokrysol WF1) in an ultrasonic inhaler. In experiments the different concentration aqueous solutions of glycerol and glycerol-polyacrylamide have been tested. The results have been obtained by the use of laser diffraction technique. The differences between characteristics of ultrasonic atomization for test liquids have been observed. The analysis of drop size histograms shows that the different sizes of drops have been formed during atomization process. The present study confirmed the previous reports which suggested that the drops size changes with the increase in viscosity of solution changes in spray characteristics were also observed. It has been shown that the shear and extensional viscosities affect the process of atomization.

  14. Suppositions, extensionality, and conditionals: a critique of the mental model theory of Johnson-Laird And Byrne (2002).

    PubMed

    Evans, Jonathan St B T; Over, David E; Handley, Simon J

    2005-10-01

    P. N. Johnson-Laird and R. M. J. Byrne proposed an influential theory of conditionals in which mental models represent logical possibilities and inferences are drawn from the extensions of possibilities that are used to represent conditionals. In this article, the authors argue that the extensional semantics underlying this theory is equivalent to that of the material, truth-functional conditional, at least for what they term "basic" conditionals, concerning arbitrary problem content. On the basis of both logical argument and psychological evidence, the authors propose that this approach is fundamentally mistaken and that conditionals must be viewed within a suppositional theory based on what philosophical logicians call the Ramsey test. The Johnson-Laird and Byrne theory is critically examined with respect to its account of basic conditionals, nonbasic conditionals, and counterfactuals.

  15. Influence of the potential well on the breakage rate of colloidal aggregates in simple shear and uniaxial extensional flows.

    PubMed

    Ren, Zhiqiang; Harshe, Yogesh M; Lattuada, Marco

    2015-06-02

    In this work we build on our previous paper (Harshe, Y. M.; Lattuada, M. Langmuir 2012, 28, 283-292) and compute the breakage rate of colloidal aggregates under the effect of shear forces by means of Stokesian dynamics simulations. A library of clusters made of identical spherical particles covering a broad range of masses and fractal dimension values (from 1.8 to 3.0) was generated by means of a combination of several Monte Carlo methods. DLVO theory has been used to describe the interparticle interactions, and contact forces have been introduced by means of the discrete element method. The aggregate breakage process was investigated by exposing them to well-defined shear forces, generated under both simple shear and uniaxial extensional flow conditions, and by recording the time required to reach the first breakage event. It has been found that the breakage rate of clusters was controlled by the potential well between particles as described by DLVO theory. A semiempirical Arrhenius-type exponential equation that relates the potential well to the breakage rate has been used to fit the simulation results. The dependence of the breakage process on the radius of gyration, on the external shear strength, and on the fractal dimension has been obtained, providing a very general relationship for the breakage rate of clusters. It was also found that the fragment mass distribution is insensitive to the presence of electrostatic repulsive interactions. We also clarify the physical reason for the large difference in the breakage rate of clusters between simple shear and the uniaxial extensional flow using a criterion based on the energy dissipation rate. Finally, in order to answer the question of the minimum cluster size that can break under simple shear conditions, a critical rotation number has been introduced, expressing the maximum number of rotations that a cluster exposed to simple shear could sustain before breakage.

  16. Molecular Processes Leading to “Necking” in Extensional Flow of Polymer Solutions: Using Microfluidics and Single DNA Imaging

    PubMed Central

    2016-01-01

    We study the necking and pinch-off dynamics of liquid droplets that contain a semidilute polymer solution of polyacrylamide close to overlap concentration by combining microfluidics and single DNA observation. Polymeric droplets are stretched by passing them through the stagnation point of a T-shaped microfluidic junction. In contrast with the sudden breakup of Newtonian droplets, a stable neck is formed between the separating ends of the droplet which delays the breakup process. Initially, polymeric filaments experience exponential thinning by forming a stable neck with extensional flow within the filament. Later, thin polymeric filaments develop a structure resembling a series of beads-on-a-string along their length and finally rupture during the final stages of the thinning process. To unravel the molecular picture behind these phenomena, we integrate a T-shaped microfluidic device with advanced fluorescence microscopy to visualize stained DNA molecules at the stagnation point within the necking region. We find that the individual polymer molecules suddenly stretch from their coiled conformation at the onset of necking. The extensional flow inside the neck is strong enough to deform and stretch polymer chains; however, the distribution of polymer conformations is broad, and it remains stationary in time during necking. Furthermore, we study the dynamics of single molecules during formation of beads-on-a-string structure. We observe that polymer chains gradually recoil inside beads while polymer chains between beads remain stretched to keep the connection between beads. The present work effectively extends single molecule experiments to free surface flows, which provides a unique opportunity for molecular-scale observation within the polymeric filament during necking and rupture. PMID:28216791

  17. Molecular Processes Leading to "Necking" in Extensional Flow of Polymer Solutions: Using Microfluidics and Single DNA Imaging.

    PubMed

    Sachdev, Shaurya; Muralidharan, Aswin; Boukany, Pouyan E

    2016-12-27

    We study the necking and pinch-off dynamics of liquid droplets that contain a semidilute polymer solution of polyacrylamide close to overlap concentration by combining microfluidics and single DNA observation. Polymeric droplets are stretched by passing them through the stagnation point of a T-shaped microfluidic junction. In contrast with the sudden breakup of Newtonian droplets, a stable neck is formed between the separating ends of the droplet which delays the breakup process. Initially, polymeric filaments experience exponential thinning by forming a stable neck with extensional flow within the filament. Later, thin polymeric filaments develop a structure resembling a series of beads-on-a-string along their length and finally rupture during the final stages of the thinning process. To unravel the molecular picture behind these phenomena, we integrate a T-shaped microfluidic device with advanced fluorescence microscopy to visualize stained DNA molecules at the stagnation point within the necking region. We find that the individual polymer molecules suddenly stretch from their coiled conformation at the onset of necking. The extensional flow inside the neck is strong enough to deform and stretch polymer chains; however, the distribution of polymer conformations is broad, and it remains stationary in time during necking. Furthermore, we study the dynamics of single molecules during formation of beads-on-a-string structure. We observe that polymer chains gradually recoil inside beads while polymer chains between beads remain stretched to keep the connection between beads. The present work effectively extends single molecule experiments to free surface flows, which provides a unique opportunity for molecular-scale observation within the polymeric filament during necking and rupture.

  18. Slip preference on pre-existing faults: a guide tool for the separation of heterogeneous fault-slip data in extensional stress regimes

    NASA Astrophysics Data System (ADS)

    Tranos, Markos D.

    2012-05-01

    Synthetic fault-slip data have been considered in the present paper, in order to examine through a simple graphical manner the validity and use of the widely mentioned and applied criteria such as the slip preference, slip tendency, kinematic (P and T) axes, transport orientation and strain compatibility. The examination and description concern extensional stress regimes whose greatest principal stress axis (σ1) always remains in vertical position as in Andersonian stress states. In particular, radial extension (RE), radial-pure extension (RE-PE), pure extension (PE), pure extension-transtension (PE-TRN) and transtension (TRN) are examined with the aid of the Win-Tensor stress inversion software. In all of these extensional stress regimes only extensional faults can be activated. The lower dip angle of the reactivated faults is about 40° assuming that the coefficient of friction is no smaller than 0.6. The increase of the stress ratio and/or the fault dip angle up to 70° results in the increase of the slip deviation from the normal activation. Based on the present examination of the slip preference and slip tendency in different extensional stress regimes, a new simple and practical method is proposed herein in order to separate originally heterogeneous fault-slip data into homogeneous fault groups, by which different extensional stress regimes could be determined. The application of the method on the already published fault-slip data of Lemnos Island supports its validity since over 90% the resulted fault groups and stress regimes coincide to the already published ones.

  19. Alaska: A twenty-first-century petroleum province

    USGS Publications Warehouse

    Bird, K.J.

    2001-01-01

    Alaska, the least explored of all United States regions, is estimated to contain approximately 40% of total U.S. undiscovered, technically recoverable oil and natural-gas resources, based on the most recent U.S. Department of the Interior (U.S. Geological Survey and Minerals Management Service) estimates. Northern Alaska, including the North Slope and adjacent Beaufort and Chukchi continental shelves, holds the lion's share of the total Alaskan endowment of more than 30 billion barrels (4.8 billion m3) of oil and natural-gas liquids plus nearly 200 trillion cubic feet (5.7 trillion m3) of natural gas. This geologically complex region includes prospective strata within passive-margin, rift, and foreland-basin sequences. Multiple source-rock zones have charged several regionally extensive petroleum systems. Extensional and compressional structures provide ample structural objectives. In addition, recent emphasis on stratigraphic traps has demonstrated significant resource potential in shelf and turbidite systems in Jurassic to Tertiary strata. Despite robust potential, northern Alaska remains a risky exploration frontier - a nexus of geologic complexity, harsh economic conditions, and volatile policy issues. Its role as a major petroleum province in this century will depend on continued technological innovations, not only in exploration and drilling operations, but also in development of huge, currently unmarketable natural-gas resources. Ultimately, policy decisions will determine whether exploration of arctic Alaska will proceed.

  20. Regional geomorphology and history of Titan's Xanadu province

    USGS Publications Warehouse

    Radebaugh, J.; Lorenz, R.D.; Wall, S.D.; Kirk, R.L.; Wood, C.A.; Lunine, J.I.; Stofan, E.R.; Lopes, R M.C.; Valora, P.; Farr, T.G.; Hayes, A.; Stiles, B.; Mitri, G.; Zebker, H.; Janssen, M.; Wye, L.; LeGall, A.; Mitchell, K.L.; Paganelli, F.; West, R.D.; Schaller, E.L.; ,

    2011-01-01

    Titan's enigmatic Xanadu province has been seen in some detail with instruments from the Cassini spacecraft. The region contains some of the most rugged, mountainous terrain on Titan, with relief over 2000 m. Xanadu contains evolved and integrated river channels, impact craters, and dry basins filled with smooth, radar-dark material, perhaps sediments from past lake beds. Arcuate and aligned mountain chains give evidence of compressional tectonism, yet the overall elevation of Xanadu is puzzlingly low compared to surrounding sand seas. Lineations associated with mountain fronts and valley floors give evidence of extension that probably contributed to this regional lowering. Several locations on Xanadu's western and southern margins contain flow-like features that may be cryovolcanic in origin, perhaps ascended from lithospheric faults related to regional downdropping late in its history. Radiometry and scatterometry observations are consistent with a water–ice or water–ammonia–ice composition to its exposed, eroded, fractured bedrock; both microwave and visible to near-infrared (v-nIR) data indicate a thin overcoating of organics, likely derived from the atmosphere. We suggest Xanadu is one of the oldest terrains on Titan and that its origin and evolution have been controlled and shaped by compressional and then extensional tectonism in the icy crust and ongoing erosion by methane rainfall.

  1. Oil and Gas Resources of the Arctic Alaska Petroleum Province

    USGS Publications Warehouse

    Houseknecht, David W.; Bird, Kenneth J.

    2006-01-01

    The Arctic Alaska Petroleum Province, encompassing all the lands and adjacent Continental Shelf areas north of the Brooks Range-Herald arch, is one of the most petroleum-productive areas in the United States, having produced about 15 billion bbl of oil. Seven unitized oil fields currently contribute to production, and three additional oil fields have been unitized but are not yet producing. Most known petroleum accumulations involve structural or combination structural-stratigraphic traps related to closure along the Barrow arch, a regional basement high, which has focused regional hydrocarbon migration since Early Cretaceous time. Several oil accumulations in stratigraphic traps have been developed in recent years. In addition to three small gas fields producing for local consumption, more than 20 additional oil and gas discoveries remain undeveloped. This geologically complex region includes prospective strata within passive-margin, rift, and foreland-basin sequences. Oil and gas were generated from multiple source rocks throughout the region. Although some reservoired oils appear to be derived from a single source rock, evidence for significant mixing of hydrocarbons from multiple source rocks indicates a composite petroleum system. Both extensional and contractional tectonic structures provide ample exploration targets, and recent emphasis on stratigraphic traps has demonstrated a significant resource potential in shelf and turbidite sequences of Jurassic through Tertiary age. Recent estimates of the total mean volume of undiscovered resources in the Arctic Alaska Petroleum Province by the U.S. Geological Survey and U.S. Minerals Management Service are more than 50 billion bbl of oil and natural-gas liquids and 227 trillion ft3 of gas, distributed approximately equally between Federal offshore and combined onshore and State offshore areas.

  2. Short-lived and discontinuous intraplate volcanism in the South Pacific: Hot spots or extensional volcanism?

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.; Staudigel, Hubert; Pringle, Malcolm S.; Wijbrans, Jan R.

    2003-10-01

    South Pacific intraplate volcanoes have been active since the Early Cretaceous. Their HIMU-EMI-EMII mantle sources can be traced back into the West Pacific Seamount Province (WPSP) using plate tectonic reconstructions, implying that these distinctive components are enduring features within the Earth's mantle for, at least, the last 120 Myr. These correlations are eminent on the scale of the WPSP and the South Pacific Thermal and Isotopic Anomaly (SOPITA), but the evolution of single hot spots emerges notably more complicated. Hot spots in the WPSP and SOPITA mantle regions typically display intermittent volcanic activity, longevities shorter than 40 Myr, superposition of hot spot volcanism, and motion relative to other hot spots. In this review, we use 40Ar/39Ar seamount ages and Sr-Nd-Pb isotopic signatures to map out Cretaceous volcanism in the WPSP and to characterize its evolution with respect to the currently active hot spots in the SOPITA region. Our plate tectonic reconstructions indicate cessation of volcanism during the Cretaceous for the Typhoon and Japanese hot spots; whereas the currently active Samoan, Society, Pitcairn and Marquesas hot spots lack long-lived counterparts in the WPSP. These hot spots may have become active during the last 20 Myr only. The other WPSP seamount trails can be only "indirectly" reconciled with hot spots in the SOPITA region. Complex age distributions in the Magellan, Anewetak, Ralik and Ratak seamount trails would necessitate the superposition of multiple volcanic trails generated by the Macdonald, Rurutu and Rarotonga hot spots during the Cretaceous; whereas HIMU-type seamounts in the Southern Wake seamount trail would require 350-500 km of hot spot motion over the last 100 Myr following its origination along the Mangaia-Rurutu "hotline" in the Cook-Austral Islands. These observations, however, violate all assumptions of the classical Wilson-Morgan hot spot hypothesis, indicating that long-lived, deep and fixed mantle

  3. The Late Cretaceous I- and A-type granite association of southeast China: Implications for the origin and evolution of post-collisional extensional magmatism

    NASA Astrophysics Data System (ADS)

    Zhao, Jiao-Long; Qiu, Jian-Sheng; Liu, Liang; Wang, Rui-Qiang

    2016-01-01

    We present new geochronological, mineralogical, and geochemical data for granitic plutons that crop out within the Zhoushan archipelago, northeastern coastal Zhejiang Province, in order to constrain their origin, and the genetic relationship between the I- and A-type granites. These granites can be divided into two groups: (1) the northern I-type Putuoshan (PTS) and Dadong'ao (DDA) plutons; and (2) the southern A-type Daqingshan (DQS), Taohuadao (THD), and Xiazhidao (XZD) plutons. Zircon LA-ICP-MS U-Pb dating yielded ages of 98-96 Ma for the northern I-type plutons and 89-86 Ma for the southern A-type plutons. All of these granites are highly siliceous, K-rich, and have similar total alkali and total rare earth element (REE) abundances. However, there are also geochemical differences between the I-type and the A-type granites. The northern I-type alkali-feldspar granites are high-K calc-alkaline, metaluminous to mildly peraluminous, contain low concentrations of the high field strength elements (HFSE; e.g., Nb, Ta, Zr, and Hf), and have low Ga/Al ratios (2.04-2.44). In contrast, the southern A-type granites are peralkaline and F-rich, and have lower CaO and Al2O3 concentrations, and higher Fe2O3T and HFSE concentrations and Ga/Al ratios (3.25-3.86). Meanwhile, they have slightly higher heavy REE (HREE) concentrations, and are more depleted in Ba, Sr, P, Ti, and Eu than the northern I-type granites. Both the I- and A-type granites have homogeneous whole-rock Nd and highly variable zircon Hf isotopic compositions. Of note, the southern peralkaline A-type granites appear to have more radiogenic Nd and Hf isotope compositions than the northern I-type granites. The present data, together with the results of a previous study on mafic enclaves within the PTS pluton, suggest that the northern I-type alkali-feldspar granites were generated by mixing of mantle-derived material with crustal-derived magmas that formed by dehydration melting of mica-bearing basaltic rocks

  4. Syn-orogenic extensional pulses within the contractional history of thrust wedges. The Val di Lima low-angle normal fault case study, Northern Apennines, Italy.

    NASA Astrophysics Data System (ADS)

    Clemenzi, Luca; Molli, Giancarlo; Storti, Fabrizio; Muchez, Philippe; Swennen, Rudy; Torelli, Luigi

    2014-05-01

    In this contribution we describe the Val di Lima low-angle fault system, a kilometric-scale extensional structure exposed in the central sector of the Northern Apennines thrust wedge, Italy. The low-angle extensional fault system delaminates the right-side-up limb of a km-scale recumbent isoclinal anticline that affects the carbonate-dominated Late Triassic to early Early Miocene non-metamorphic Tuscan succession. The low-angle fault system, in turn, is affected by superimposed folding and late-tectonic high-angle extensional faulting. The three-dimensional configuration of the low-angle fault system has been investigated through detailed structural mapping and restoration of the superimposed deformations, while the fault damage zone architecture has been characterized in outcrops with appropriate exposure. Pressure-depth conditions and palaeofluid evolution of the fault system have been studied through microstructural, mineralogical, petrographic, fluid inclusion and stable isotope analysis of fault rocks and fault-related calcite and quartz veins. Our results show that the low-angle fault system was active during exhumation of the Tuscan succession, at estimated conditions of about 180°C and 5.2 km depth. The fault system had a twofold influence on fluid circulation within the orogenic wedge: i) it allowed the migration of low-salinity fluids, due to the increased permeability along the fault zone; ii) it favored footwall fluid overpressures where the fault core acted as an efficient hydraulic barrier. Abundant fluid circulation in fault damage zones also characterized the late-stage evolution of the low-angle fault system, allowing the recrystallization of calcite veins and limestone host rocks at shallower conditions (~ 4 km). Within this P-T framework, the fault zone architecture shows important differences, related to the different lithologies involved in the fault system and to the role played by the fluids during deformation. In particular, footwall fluid

  5. Extensional Detachment faulting in melange rocks. Plurikilometres migration by W the External Zone (Cordillera Bética, Spain)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Azañon, Jose Miguel; Rodríguez, Jose; Mateos, Rosa Maria

    2014-05-01

    The synthesis and correlation of units carried out in the continuous geological map (Roldán et al., 2012), has revealed a fragmentation of the carbonate outcrops belong to the Subbetic Domain (García-Hernández et al., 1980). Subbetic NW verging thrust and fold axial traces have not lateral continuity and Jurassic carbonate outscrops appear as klippes on the olistotromic unit. These ductile structures that can be observed in the internal structure of these jurassic blocks are unrelated to the brittle-ductile deformation bands observed at the basal pelitic levels. Basal detachments are rooted in: a) the Olistostromic unit, a Upper Langhian-Lower Serravallian breccia constituted by gypsum-bearing clay and marls; b) Cretaceous-Tertiary marly sedimentary rocks (Rodríguez-Fernández, et al., 2013) . In both kind of rocks, cataclastic structures allows to infer a top-to-the WSW displacement. Paleostress measurements, made on these detachments levels, are compatible with a extensional regime (Roldán et al., 2012). At the same time, the analysis and interpretation of subsurface data (seismic surveys and borehole testing) shows that the Subbetic Domain (External Subbetic, Molina 1987) are affected by westward low-angle normal faults. A balanced cross-section, based on morphological and cartographic data in the area between Sierra de Cabra and Sierra de Alta Coloma (Valdepeñas de Jaén), shows plurikilometric displacements which has been produced during Late Serravallian-Early Tortonian times. References: García-Hernández, M., López-Garrido, A.C., Rivas, P., Sanz de Galdeano, C., Vera, J.A. (1980): Mesozoic paleogeographic evolution of the zones of the Betic Cordillera. Geol. Mijnb. 59 (2). 155-168. Molina, J.M. (1987). Análisis de facies del Mesozoico en el Subbético. Tesis Doctoral, Univ. Granada. 518 p. Rodríguez-Fernández, J., Roldán, F. J., Azañón, J.M. y García-Cortés, A. (2013). El colapso gravitacional del frente orogénico a lpino en el Dominio Subb

  6. Active Extensional Faulting at the Southern Half-Graben Belt of the Tepic-Zacoalco Rift, Western Mexico

    NASA Astrophysics Data System (ADS)

    Rosas-Elguera, J.; Ferrari, L.; Delgado, M.; Uribe, A.; Valdivia, L.; Castillo, R.

    2003-12-01

    In the past decade much debate has centered upon the kinematics and the mechanism of continental deformation in western Mexico and the motion of the Jalisco block relative to North America. Two distinct models have been proposed. The first one suggest a NW-motion of the Jalisco block that would implies a right-lateral faulting along the Tepic-Zacoalco rift (TZR). More recently others authors have documented a N-NE extensional tectonics active since late Miocene and suggested that the continental boundaries of the Jalisco block, are older structures reactivated by plate boundary forces. Studies on the crustal seismicity and the kinematics of Quaternary faults provide another constraint on the direction of motion between the Jalisco block and North America. On November 4, 5, 6, and 7, 1995, one month after the October 09, 1995, Manzanillo earthquake (Mw = 8.0), a swarm of small events was felt in the Amatlan de Ca¤as half-graben and recorded by the regional seismic network of Comision Federal de Electricidad. The coda magnitude of the largest event was Mc = 2.5-3.6 and the events were located depth ranging from 6 to 10 km. This seismic activity provoked that people from Pie de la Cuesta and Yerbabuena villages were evacuated. After that a seismic station equipped with an analogic seismograph MEQ-800 at Pie de la Cuesta was installed for three months. During the same time, October, 1995, some houses distributed along a WNW trend in Ameca city underwent severe damages, they are. The digital elevations model of the Ameca city suggest that several structures tectonics are shorter than 2 km are present in the area. The present direction of motion of the Rivera plate relative to North America plate along Middle America Trench has been estimated between N19° E to N48° E (e.g. Bandy et al., 1996). During the October 09, 1995, subduction-related earthquake (Mw = 8.0) a GPS network recorded a SW motion of the Jalisco block which could be associated to an elastic deformation

  7. Tectonomagmatic relationship between the Sierra Madre Occidental ignimbrite flare-up and the southern Basin and Range province

    NASA Astrophysics Data System (ADS)

    Aguirre-Diaz, G. J.; Labarthe-Hernandez, G.

    2004-12-01

    The Sierra Madre Occidental (SMO) is a Mid-Tertiary, large-volume, ignimbrite province at least 1,200 km long and 200-500 km wide, extending continuously from the U.S.-Mexico border (31\\deg N) to its intersection with the Mexican Volcanic Belt (21\\deg N). Considering the average thickness of 1,000 m for the ignimbrite plateau, based on several measured sections along the province, and the average wide of the province of 300 km, a conservative estimate of the physical volume of the SMO ignimbrites is about 360,000 km3. The southern part of the Basin and Range province is in Mexico. This extensional province overlaps in space and time with the SMO ignimbrite flare-up and formed NW- to NE-trending normal faults that bound many large grabens, which are particularly long and deep in the southern SMO. Basin and Range faulting occurred between at least 32 Ma and 12 Ma with both limits probably extending until the Eocene and the Quaternary. Ignimbrite activity can be as old as 51 Ma and as young as 17-16 Ma, but most of the ignimbrite volume was erupted in the 38-23 Ma period. Thus, the ignimbrite flare-up can be defined as a period of intense explosive volcanic activity that produced enormous volumes of silicic ignimbrite sheets, which took place mainly between 38 and 23 Ma in Mexico. The ignimbrite flare-up coincided in time with peaks in Basin and Range faulting, and the ignimbrite activity apparently migrated from the east-northeast to the west-southwest, i.e., from central Chihuahua (38-27 Ma) to Durango-Tayoltita-Nazas (32-29 Ma) to Zacatecas-Tepic (24-23 Ma), finishing by 16 Ma at Jalisco-Nayarit, as deduced from the compilation of geologic works done in the SMO. It is unknown yet whether there was a west-southward migration of Basin and Range faulting and if the ignimbrite flare-up occurred episodically as peaks (38-27 Ma, 32-29 Ma, and 24-23 Ma) or was continuous. Nevertheless, by the time that the ignimbrite flare-up started, the Basin and Range extension was

  8. Extensional Flow of a Polystyrene Boger Fluid Through a 4:1:4 Axisymmetric Contraction/Expansion

    NASA Technical Reports Server (NTRS)

    Rothstein, Jonathan P.; McKinley, Gareth H.

    1999-01-01

    The creeping flow of a dilute (0.025 wt%) monodisperse polystyrene/polystyrene Boger fluid through a 4:1:4 axisymmetric contraction/expansion is experimentally observed for a wide range of Deborah numbers. Pressure drop measurements across the orifice plate show a large extra pressure drop that increases monotonically with Deborah number above the value observed for a similar Newtonian fluid at the same flow rate. This enhancement in the dimensionless pressure drop is not associated with the onset of a flow instability, yet it is not predicted by existing steady-state or transient numerical computations with simple dumbbell models. It is conjectured that this extra pressure drop is the result of an additional dissipative contribution to the polymeric stress arising from a stress-conformation hysteresis in the strong non-homogeneous extensional flow near the contraction plane. Such a hysteresis has been independently measured and computed in recent studies of homogeneous transient uniaxial stretching of PS/PS Boger fluids. Flow visualization and velocity field measurements using digital particle image velocimetry (DPIV) show large upstream growth of the corner vortex with increasing Deborah number. At large Deborah numbers, the onset of an elastic instability is observed, first locally as small amplitude fluctuations in the pressure measurements, and then globally as an azimuthal precessing of the upstream corner vortex accompanied by periodic oscillations in the pressure drop across the orifice.

  9. Brittle extension of the continental crust along a rooted system of low-angle normal faults: Colorado River extensional corridor

    NASA Technical Reports Server (NTRS)

    John, B. E.; Howard, K. A.

    1985-01-01

    A transect across the 100 km wide Colorado River extensional corridor of mid-Tertiary age shows that the upper 10 to 15 km of crystalline crust extended along an imbricate system of brittle low-angle normal faults. The faults cut gently down a section in the NE-direction of tectonic transport from a headwall breakaway in the Old Woman Mountains, California. Successively higher allochthons above a basal detachment fault are futher displaced from the headwall, some as much as tens of kilometers. Allochthonous blocks are tilted toward the headwall as evidenced by the dip of the cappoing Tertiary strata and originally horizontal Proterozoic diabase sheets. On the down-dip side of the corridor in Arizona, the faults root under the unbroken Hualapai Mountains and the Colorado Plateau. Slip on faults at all exposed levels of the crust was unidirectional. Brittle thinning above these faults affected the entire upper crust, and wholly removed it locally along the central corridor or core complex region. Isostatic uplift exposed metamorphic core complexes in the domed footwall. These data support a model that the crust in California moved out from under Arizona along an asymmetric, rooted normal-slip shear system. Ductile deformation must have accompanied mid-Tertiary crustal extension at deeper structural levels in Arizona.

  10. Three-port impedance model of a piezoelectric bar element: Application to generation and damping of extensional waves

    NASA Astrophysics Data System (ADS)

    Jansson, A.; Lundberg, B.

    2008-09-01

    A straight bar element containing piezoelectric members is viewed as a linear system with one electrical and two mechanical ports where it can interact with external electrical and mechanical devices through voltage, current, forces and velocities. A generalized force vector, with one voltage and two forces as elements, is expressed as the product of an impedance matrix and a generalized velocity vector, with one current and two velocities, as elements. Due to symmetry and reciprocity, this matrix is defined by four of its nine elements. Two applications are considered for a piezoelectric bar element (PBE) that constitutes a part of a long elastic or viscoelastic bar, viz. generation and damping of extensional waves in the bar. In the first, the PBE is driven by a given input voltage or by the output voltage from a linear power amplifier. In the second, the PBE supplies an output voltage to an external load. In numerical simulations carried out for a specific laminated PBE, an elastic bar, a serial RL load and a bell-shaped incident wave, the highest fraction of wave energy dissipated was 8.1%. This is much less than the 50% achievable for a harmonic wave under condition of electrical impedance matching.

  11. Piezoelectric generation of extensional waves in a viscoelastic bar by use of a linear power amplifier: Theoretical basis

    NASA Astrophysics Data System (ADS)

    Jansson, A.; Lundberg, B.

    2007-09-01

    A system consisting of a linear power amplifier driving a piezoelectric actuator pair attached to a long viscoelastic bar is analysed. Coupled piezoelectric theory is used, and allowance is made for the dynamics of the amplifier and of the actuators. Formulae are derived for the relation between the input voltage to the amplifier and the normal force associated with extensional waves generated in the bar and for the load impedance constituted by the actuator-bar assembly. It is established that the mechanical work performed on the external parts of the bar at the actuator/bar interfaces is at most equal to the electrical energy supplied by the amplifier. The results are applied to a three-parameter viscoelastic bar and to an elastic bar, and the effects of the cut-off frequency, without load, and the output impedance of the amplifier are examined. For the elastic bar, sharp response minima occur at frequencies that are integral multiples of the inverse transit time through the actuator region. For the viscoelastic bar, the corresponding minima are less sharp and deep. The input voltage to the amplifier required to produce a desired output wave at the actuator/bar interfaces can be determined provided that the spectrum of this wave is not too broad.

  12. Extensional flow of low-viscosity fluids in capillary bridges formed by pulsed surface acoustic wave jetting

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, P. K.; McDonnell, A. G.; Prabhakar, R.; Yeo, L. Y.; Friend, J.

    2011-02-01

    Forming capillary bridges of low-viscosity (lsim10 mPa s) fluids is difficult, making the study of their capillary-thinning behavior and the measurement of the fluid's extensional viscosity difficult as well. Current techniques require some time to form a liquid bridge from the stretching of a droplet. Rapidly stretching a liquid bridge using these methods can cause its breakup if the viscosity is too low. Stretching more slowly allows the bridge to thin and break up before a suitable bridge geometry can be established to provide reliable and accurate rheological data. Using a pulsed surface acoustic wave to eject a jet from a sessile droplet, a capillary bridge may be formed in about 7.5 ms, about seven times quicker than current methods. With this approach, capillary bridges may be formed from Newtonian and non-Newtonian fluids having much lower viscosities—water, 0.04% by weight solution of high-molecular-weight (7 MDa) polystyrene in dioctyl phthalate and 0.25% fibrinogen solution in demineralized water, for example. Details of the relatively simple system used to achieve these results are provided, as are experimental results indicating deviations from a Newtonian response by the low-viscosity non-Newtonian fluids used in our study.

  13. Deformation microstructures and diagenesis in sandstone adjacent to an extensional fault: Implications for the flow and entrapment of hydrocarbons

    SciTech Connect

    Hippler, S.J. )

    1993-04-01

    Microstructural and diagenetic analyses of the North Scapa Sandstone in the hanging wall of the North Scapa fault, Orkney, Scotland, provide insight into the relationship between faulting and fluid flow during basin development. The results demonstrate the influence of this relationship on fault sealing processes and hydrocarbon migration. During development of the Orcadian basin in the Middle Devonian, the fault moved in an extensional sense. Dilatancy associated with cataclastic deformation caused localization of fluid flow and resulted in the precipitation of quartz and illite cement in the North Scapa Sandstone up to 1 m from the fault plane. This diagenetic event, coupled with cataclastic grain-size reduction, significantly reduced the porosity and permeability of the sandstone directly adjacent to the fault. These processes are effective sealing mechanisms within the sandstone. Lacustrine source rocks in the Orcadian basin reached maturation during the latest Devonian to middle Carboniferous. At the end of this time, the basin was uplifted, and the North Scapa fault was reactivated in a normal, but dominantly oblique-slip sense. This later deformation was accommodated directly outside the sealed zone and resulted in the development of broad (10-20 cm) breccia zones and narrow (<10 cm) cataclastic bands. Further dilatancy associated with the cataclastic deformation channelized hydrocarbon flow through the high-strain breccia zones and cataclastic bands. These observations indicate that fault activity that is broadly coincident with maturation and expulsion of hydrocarbons within a basin can directly influence the location of migration pathways. 81 refs., 14 figs., 1 tab.

  14. Comparison of quartz tuning forks and AlN-based extensional microresonators for viscosity measurements in oil/fuel mixtures

    NASA Astrophysics Data System (ADS)

    Toledo, J.; Manzaneque, T.; Hernando-García, J.; Vazquez, J.; Ababneh, A.; Seidel, H.; Lapuerta, M.; Sánchez-Rojas, J. L.

    2013-05-01

    In-situ monitoring of the physical properties of liquids is of great interest in the automotive industry. For example, lubricants are subject to dilution with diesel fuel as a consequence of late-injection processes, which are necessary for regenerating diesel particulate filters. This dilution can be determined by tracking the viscosity and the density of the lubricant. Here we report the test of two in-plane movement based resonators to explore their capability to monitor oil dilution with diesel and biodiesel. One of the resonators is the commercially available millimeter-sized quartz tuning fork, working at 32.7 kHz. The second resonator is a state-of-the-art micron-sized AlN-based rectangular plate, actuated in the first extensional mode in the MHz range. Electrical impedance measurements were carried out to characterize the performance of the structures in various liquid media in a wide range of viscosities. These measurements were completed with the development of low-cost electronic circuits to track the resonance frequency and the quality factor automatically, these two parameters allow to obtain the viscosity of various fluids under investigation, as in the case of dilution of lubricant SAE 15W40 and biodiesel.

  15. Extensional fault-propagation folding and base-level change as controls on growth-strata geometries

    NASA Astrophysics Data System (ADS)

    Gawthorpe, Rob; Hardy, Stuart

    2002-01-01

    Outcrop and analogue modelling studies indicate that upward widening zones of distributed deformation, often monoclinal folds, form above blind normal faults and are particularly common features at the depositional surface during the early stages of rifting. With increasing displacement (strain), such folds are cut by faults as they propagate upwards into the cover. We use a kinematic model of fault-propagation folding above a blind extensional fault, together with a sedimentary model of coarse-grained clastic deposition, to investigate growth-strata geometries associated with fault-tip monoclines. In particular, we consider coarse-grained deltaic deposition where sedimentary geometries are markedly different from the simple sub-horizontal 'fill-to-the-top' sedimentation used in most growth-strata models. For a given fault dip and slip rate, growth-strata geometries are strongly influenced by the fault-propagation to slip ratio ( p/ s) and the width of the zone of distributed deformation. However, base-level changes also act as fundamental controls on sequence development. The results of a number of experiments compare favourably to well-documented examples of growth-strata. This study highlights the importance of integrating structural and stratigraphic studies in interpreting both fault/fold kinematics and the controls on stratigraphy; kinematic studies need to address the depositional geometry of stratal surfaces, whereas sequence stratigraphic interpretation of stratal patterns must deconvolve tectonic rotation and translation from depositional architecture.

  16. The Montalet granite, Montagne Noire, France: An Early Permian syn-extensional pluton as evidenced by new U-Th-Pb data on zircon and monazite

    NASA Astrophysics Data System (ADS)

    Poilvet, Jean-Charles; Poujol, Marc; Pitra, Pavel; Van Den Driessche, Jean; Paquette, Jean-Louis

    2011-07-01

    Dating the magmatism in the Montagne Noire gneiss dome in the southern French Massif Central is a key point for understanding the Late Palaeozoic evolution of this part of the Variscan belt, which is characterised by compressive tectonics during the Carboniferous and extensional tectonics during Stephanian-Permian times. The Montalet granite crops out in the north-western part of the dome and was first considered as an early syntectonic intrusion related to compressive deformation. More recently, it has been dated at 327 Ma and considered as contemporaneous with the diapiric ascent of the Montagne Noire gneiss dome before the Stephanian-Permian extension. We show that in fact, this pluton was emplaced 294 ± 1 Ma ago and is therefore contemporaneous with the Stephanian-Permian extension. This age is consistent with the interpretation of the Montagne Noire Massif as an extensional gneiss dome.

  17. A three-step model to assess shoreline and offshore susceptibility to oil spills: the South Aegean (Crete) as an analogue for confined marine basins.

    PubMed

    Alves, Tiago M; Kokinou, Eleni; Zodiatis, George

    2014-09-15

    This study combines bathymetric, geomorphological, geological data and oil spill predictions to model the impact of oil spills in two accident scenarios from offshore Crete, Eastern Mediterranean. The aim is to present a new three-step method of use by emergency teams and local authorities in the assessment of shoreline and offshore susceptibility to oil spills. The three-step method comprises: (1) real-time analyses of bathymetric, geomorphological, geological and oceanographic data; (2) oil dispersion simulations under known wind and sea current conditions; and (3) the compilation of final hazard maps based on information from (1) and (2) and on shoreline susceptibility data. The results in this paper show that zones of high to very-high susceptibility around the island of Crete are related to: (a) offshore bathymetric features, including the presence of offshore scarps and seamounts; (b) shoreline geology, and (c) the presence near the shore of sedimentary basins filled with unconsolidated deposits of high permeability. Oil spills, under particular weather and oceanographic conditions, may quickly spread and reach the shoreline 5-96 h after the initial accident. As a corollary of this work, we present the South Aegean region around Crete as a valid case-study for confined marine basins, narrow seaways, or interior seas around island groups.

  18. Implementation of a reduced order Kalman filter to assimilate ocean color data into a coupled physical-biochemical model of the North Aegean Sea.

    NASA Astrophysics Data System (ADS)

    Kalaroni, Sofia; Tsiaras, Kostas; Economou-Amilli, Athena; Petihakis, George; Politikos, Dimitrios; Triantafyllou, George

    2013-04-01

    Within the framework of the European project OPEC (Operational Ecology), a data assimilation system was implemented to describe chlorophyll-a concentrations of the North Aegean, as well the impact on the European anchovy (Engraulis encrasicolus) biomass distribution provided by a bioenergetics model, related to the density of three low trophic level functional groups of zooplankton (heterotrophic flagellates, microzooplankton and mesozooplankton). The three-dimensional hydrodynamic-biogeochemical model comprises two on-line coupled sub-models: the Princeton Ocean Model (POM) and the European Regional Seas Ecosystem Model (ERSEM). The assimilation scheme is based on the Singular Evolutive Extended Kalman (SEEK) filter and its variant that uses a fixed correction base (SFEK). For the initialization, SEEK filter uses a reduced order error covariance matrix provided by the dominant Empirical Orthogonal Functions (EOF) of model. The assimilation experiments were performed for year 2003 using SeaWiFS chlorophyll-a data during which the physical model uses the atmospheric forcing obtained from the regional climate model HIRHAM5. The assimilation system is validated by assessing the relevance of the system in fitting the data, the impact of the assimilation on non-observed biochemical parameters and the overall quality of the forecasts.

  19. Fault slip source models for the 2014 Mw 6.9 Samothraki-Gökçeada earthquake (North Aegean Trough) combining geodetic and seismological observations

    NASA Astrophysics Data System (ADS)

    Saltogianni, Vasso; Gianniou, Michail; Taymaz, Tuncay; Yolsal-ćevikbilen, Seda; Stiros, Stathis

    2015-12-01

    The 24 May 2014, Mw 6.9, Samothraki-Gökçeada shallow (depth: 11 km) earthquake along the North Aegean Trough (NAT), at the westward extension of the North Anatolian Fault Zone (NAFZ), is investigated using constraints from seismological and geodetic data. A point source solution based on teleseismic long-period P and SH waveforms suggests an essentially strike-slip faulting mechanism consisting of two subevents, while from a finite fault inversion of broadband data the rupture area and slip history were estimated. Analysis of data from 11 permanent GPS stations indicated significant coseismic horizontal displacement but no significant vertical or postseismic slip. Okada-type inversion of horizontal slip vectors, using the new TOPological INVersion algorithm, allowed precise modeling of the fault rupture both as single and preferably as double strike-slip faulting reaching the surface. Variable slip models were also computed. The independent seismological and geodetic fault rupture models are broadly consistent with each other and with structural and seismological data and indicate reactivation of two adjacent fault segments separated by a bend of the NAT. The 2014 earthquake was associated with remote clusters of low-magnitude aftershocks, produced low accelerations, and filled a gap in seismicity along the NAT in the last 50 years; faulting in the NAT seems not directly related to the sequence of recent faulting farther east, along the NAFZ and the seismic gap in the Marmara Sea near Istanbul.

  20. Marine pollution risk in a coastal city: use of an eco-genotoxic tool as a stress indicator in mussels from the Eastern Aegean Sea.

    PubMed

    Kacar, Asli; Pazi, Idil; Gonul, Tolga; Kucuksezgin, Filiz

    2016-08-01

    Coastal areas, such as bays, estuaries, and harbors, are heavily polluted since these areas are the settlements to which toxic chemicals from industrial and domestic wastes are discharged. The genetic damage was evaluated using bioindicator mussel Mytilus galloprovincialis caused by toxic chemicals (metals and polycyclic aromatic hydrocarbons) in İzmir and Çandarlı Bays (the Eastern Aegean Sea) through comet assay. Three sampling sites from the two bays were selected and the study was conducted during the spring and autumn periods. The highest levels of DNA damage expressed as %Tail-DNA were observed in İzmir Bay (34.60 % Tail-DNA) in the spring. Analysis of the correlation between PAHs and metals in mussels and %T-DNA in the hemolymph and gill cells showed a statistically significant positive correlation between %T-DNA and ∑PAH, chromium (p < 0.05). This study determined the pollution level of the İzmir and Çandarlı Bays by using the DNA damage to the mussel, which can identify the effects of environmental pollutants at the cellular levels. These results confirm that comet assay can be used to determine the temporal and spatial differences of DNA damage, and as a suitable tool for the measurement of genotoxicity in regions with low pollutant concentrations.

  1. Automatic identification of fault surfaces through Object Based Image Analysis of a Digital Elevation Model in the submarine area of the North Aegean Basin

    NASA Astrophysics Data System (ADS)

    Argyropoulou, Evangelia

    2015-04-01

    The current study was focused on the seafloor morphology of the North Aegean Basin in Greece, through Object Based Image Analysis (OBIA) using a Digital Elevation Model. The goal was the automatic extraction of morphologic and morphotectonic features, resulting into fault surface extraction. An Object Based Image Analysis approach was developed based on the bathymetric data and the extracted features, based on morphological criteria, were compared with the corresponding landforms derived through tectonic analysis. A digital elevation model of 150 meters spatial resolution was used. At first, slope, profile curvature, and percentile were extracted from this bathymetry grid. The OBIA approach was developed within the eCognition environment. Four segmentation levels were created having as a target "level 4". At level 4, the final classes of geomorphological features were classified: discontinuities, fault-like features and fault surfaces. On previous levels, additional landforms were also classified, such as continental platform and continental slope. The results of the developed approach were evaluated by two methods. At first, classification stability measures were computed within eCognition. Then, qualitative and quantitative comparison of the results took place with a reference tectonic map which has been created manually based on the analysis of seismic profiles. The results of this comparison were satisfactory, a fact which determines the correctness of the developed OBIA approach.

  2. Long-term monitoring of the impact of a capture-based bluefin tuna aquaculture on water column nutrient levels in the Eastern Aegean Sea, Turkey.

    PubMed

    Aksu, Mehmet; Kaymakçi-Başaran, Asli; Egemen, Ozdemir

    2010-12-01

    Capture-based aquaculture of Atlantic bluefin tuna in the Mediterranean has been expanding rapidly but little is known about its environmental impact. In order to understand the consequences of this new sector, long-term monitoring is needed. For this purpose, we investigated the impact of a capture-based tuna farm located in the Gerence Bay (Aegean Sea) on the water column on a seasonal basis from 2005 to 2008, where in the water column, temperature, salinity, pH, dissolved oxygen, nutrients (nitrite, nitrate, ammonium, and phosphate), and chlorophyll a, in the sediment organic carbon variables were measured. Although highest nutrient concentrations were observed at the cage station as compared to the two controls in the production period, differences were not statistically significant between stations. Monitoring of physico-chemical parameters, nutrients, and chlorophyll a in water column together with organic carbon in sediment did not show detectable impact of fattening of Atlantic bluefin tuna. This was probably caused by strong currents present in the area, location of the cages away from the coast, hence high water depth, controlled feeding, and periodic presence of tuna farming activity in the study area.

  3. The Campania-Lucania Extensional Fault System, southern Italy: A suggestion for a uniform model of active extension in the Italian Apennines

    NASA Astrophysics Data System (ADS)

    Brozzetti, F.

    2011-10-01

    By integrating new field data, seismic lines interpretation and a critical review of the literature, this work highlights a regional array of normal faults in the southern Apennines of Italy, which have been active during the Quaternary and are referred to as the "Campania-Lucania Extensional Fault System" (CLEFS). The CLEFS consists of three main NW-SE striking alignments of normal faults, which for the first time are considered genetically linked and methodically described in their geometry, kinematics and displacement. The CROP04 seismic profile, crossing the central part of the CLEFS, was strictly constrained by detailed geological surveys and reinterpreted to define the downdip trajectory of the major normal faults. These latter have been observed to splay from an east dipping low-angle detachment surface penetrating the upper crust to depths of 12-13 km. The time-space evolution of the faults and the associated basins was defined through a review of the stratigraphic data on the syntectonic deposits. As regards the overall geometry and the associate sense of shear (top-to-east), the CLEFS sensibly differs from the extensional features described previously in this region but shows surprising affinities with the "Etrurian Fault System," an extensional megastructure of the northern Apennines. Remarkable similarities concern the extent, the surface and subsurface geometry, the timing of activity and the amount of the associated deformation. These common characters recognized over a belt nearly 600 km long lead to formulation of a low-angle normal fault-driven extension geometrical-kinematic model, which is sound for the whole active extensional belt of Italy.

  4. From colloidal spheres to nanofibrils: extensional flow properties of mineral pigment and mixtures with micro and nanofibrils under progressive double layer suppression.

    PubMed

    Dimic-Misic, Katarina; Hummel, Michael; Paltakari, Jouni; Sixta, Herbert; Maloney, Thad; Gane, Patrick

    2015-05-15

    Suspensions of mineral pigment and cellulose fibrillar derivatives are materials regularly found in the forest products industries, particularly in paper and board production. Many manufacturing processes, including forming and coating employ flow geometries incorporating extensional flow. Traditionally, colloidal mineral pigment suspensions have been considered to show little to no non-linear behaviour in extensional viscosity. Additionally, recently, nanofibrillar materials, such as microfibrillar (MFC) and nanofibrillar cellulose (NFC), collectively termed MNFC, have been confirmed by their failure to follow the Cox-Merz rule to behave more as particulate material rather than showing polymeric rheological properties when dispersed in water. Such suspensions and their mixtures are currently intensively investigated to enable them to generate likely enhanced composite material properties. The processes frequently involve exposure to increasing levels of ionic strength, coming either from the weak solubility of pigments, such as calcium carbonate, or retained salts arising from the feed fibre source processing. By taking the simple case of polyacrylate stabilised calcium carbonate suspension and comparing the extensional viscosity as a function of post extension capillary-induced Hencky strain on a CaBER extensional rheometer over a range of increasing salt concentration, it has been shown that the regime of constriction changes as the classic DLVO double layer is progressively suppressed. This change is seen to lead to a characteristic double (bimodal) measured viscosity response for flocculated systems. With this novel characteristic established, more complex mixed suspensions of calcium carbonate, clay and MNFC have been studied, and the effects of fibrils versus flocculation identified and where possible separated. This technique is suggested to enable a better understanding of the origin of viscoelasticity in these important emerging water-based suspensions.

  5. Geometry of miocene extensional deformation, lower Colorado River Region, Southeastern California and Southwestern Arizona: Evidence for the presence of a regional low-angle normal fault

    NASA Technical Reports Server (NTRS)

    Tosdal, R. M.; Sherrod, D. R.

    1985-01-01

    The geometry of Miocene extensional deformation, which changes along a 120 km-long, northeast-trending transect from the southestern Chocolate Mountains, southeastern California, to the Trigo and southern Dome Rock Mountains, southwestern Arizona is discussed. Based upon regional differences in the structural response to extension and estimated extensional strain, the transet can be divided into three northwesterly-trending structural domains. From southwest to northeast, these domains are: (1) southestern Chocolate-southernmost Trigo Mountains; (2) central to northern Trigo Mountains; and (3) Trigo Peaks-southern Dome Rock Mountains. All structures formed during the deformation are brittle in style; fault rocks are composed of gouge, cohesive gouge, and local microbreccia. In each structural domain, exposed lithologic units are composed of Mesozoic crystalline rocks unconformably overlain by Oligocene to Early Miocene volcanic and minor interbedded sedimentary rocks. Breccia, conglomerate, and sandstone deposited synchronously with regional extension locally overlie the volcanic rocks. Extensional deformation largely postdated the main phase of volcanic activity, but rare rhyolitic tuff and flows interbedded with the syndeformational clastic rocks suggest that deformation began during the waning stages of valcanism. K-Ar isotopic ages indicate that deformation occurred in Miocene time, between about 22 and m.y. ago.

  6. Synthesis and characterization of high molecular weight water-soluble polymers to study the role of extensional viscosity in polymeric drag reduction

    NASA Astrophysics Data System (ADS)

    Cowan, Martin E.

    Several high molecular weight water-soluble acrylamide copolymers identified as efficient drag reducers have been synthesized, characterized, and examined for drag reduction effectiveness. Commercially supplied poly(ethylene oxide) polymers of varying molecular weight were also characterized and studied for comparison. The resistance to polymer extension was measured using a screen extensional rheometer allowing for the local extensional viscosity of each polymer to be quantified. Copolymer composition was determined using 13C NMR. Dilute solution properties and molecular weights were determined from zero shear intrinsic viscosity measurements and multi-angle laser light scattering experiments respectively. Molecular weights ranged from 0.55 to 4.3 million grams per mole. Drag reduction measurements were performed using a rotating disk instrument. Drag reduction data were analyzed by several theoretical models. The best correlation was found using the energy model of Walsh. Empirically, drag reduction was found to be directly related to the local extensional viscosity of each polymer sample. A model is presented explaining drag reduction in terms of increased local viscosity leading to decreased turbulence characterized with a decreased local Reynolds number. Molecular weight was found to be the most important molecular parameter of the polymers studied with polymers of greater molecular weight showing superior drag reduction properties.

  7. Strain modelling of extensional fault-propagation folds based on an improved non-linear trishear model: A numerical simulation analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Haonan; Guo, Zhaojie; Yu, Xiangjiang

    2017-02-01

    This paper focuses on the strain modelling of extensional fault-propagation folds to reveal the effects of key factors on the strain accumulation and the relationship between the geometry and strain distribution of fault-related folds. A velocity-geometry-strain method is proposed for the analysis of the total strain and its accumulation process within the trishear zone of an extensional fault-propagation fold. This paper improves the non-linear trishear model proposed by Jin and Groshong (2006). Based on the improved model, the distribution of the strain rate within the trishear zone and the total strain are obtained. The numerical simulations of different parameters performed in this study indicate that the shape factor R, the total apical angle, and the P/S ratio control the final geometry and strain distribution of extensional fault-propagation folds. A small P/S ratio, a small apical angle, and an R value far greater or far smaller than 1 produce an asymmetric, narrow, and strongly deformed trishear zone. The velocity-geometry-strain analysis method is applied to two natural examples from Big Brushy Canyon in Texas and the northwestern Red Sea in Egypt. The strain distribution within the trishear zone is closely related to the geometry of the folds.

  8. Oblique transfer of extensional strain between basins of the middle Rio Grande rift, New Mexico: fault kinematic and paleostress constraints

    USGS Publications Warehouse

    Minor, Scott A.; Hudson, Mark R.; Caine, Jonathan Saul; Thompson, Ren A.

    2013-01-01

    The structural geometry of transfer and accommodation zones that relay strain between extensional domains in rifted crust has been addressed in many studies over the past 30 years. However, details of the kinematics of deformation and related stress changes within these zones have received relatively little attention. In this study we conduct the first-ever systematic, multi-basin fault-slip measurement campaign within the late Cenozoic Rio Grande rift of northern New Mexico to address the mechanisms and causes of extensional strain transfer associated with a broad accommodation zone. Numerous (562) kinematic measurements were collected at fault exposures within and adjacent to the NE-trending Santo Domingo Basin accommodation zone, or relay, which structurally links the N-trending, right-stepping en echelon Albuquerque and Española rift basins. The following observations are made based on these fault measurements and paleostresses computed from them. (1) Compared to the typical northerly striking normal to normal-oblique faults in the rift basins to the north and south, normal-oblique faults are broadly distributed within two merging, NE-trending zones on the northwest and southeast sides of the Santo Domingo Basin. (2) Faults in these zones have greater dispersion of rake values and fault strikes, greater dextral strike-slip components over a wide northerly strike range, and small to moderate clockwise deflections of their tips. (3) Relative-age relations among fault surfaces and slickenlines used to compute reduced stress tensors suggest that far-field, ~E-W–trending σ3 stress trajectories were perturbed 45° to 90° clockwise into NW to N trends within the Santo Domingo zones. (4) Fault-stratigraphic age relations constrain the stress perturbations to the later stages of rifting, possibly as late as 2.7–1.1 Ma. Our fault observations and previous paleomagnetic evidence of post–2.7 Ma counterclockwise vertical-axis rotations are consistent with increased

  9. Extensional tectonics of a part of the southwestern White Pine Range, Nevada: Implications for petroleum occurrence in Railroad Valley

    SciTech Connect

    Langrock, H.; Taylor, W.J.

    1995-06-01

    Extension exerts controls on migration and trapping of petroleum in rift settings, such as the Great Basin. Extensional controls are critical to the accumulation of petroleum in Nevada, including in Pine and Railroad Valleys. In these fields, reservoir permeability increased due to extension-related fracturing. These fractured reservoirs and structural traps may be contained within upper plates to regional detachments. Just northeast of Nevada`s most productive oil fields, a regionally extensive detachment is exposed in the White Pine Range. This detachment, the Blackrock fault, is a presently low, angle normal fault which dips <30{degrees} along most of its surface trace. The Blackrock fault is nonplanar and exhibits drastic changes in both orientation and geometry along its length. The amount of stratigraphic separation across the fault is also highly variable ranging from <30 to {approximately}3800 m. Upper plate structures to the Blackrock fault may influence oil fields in Railroad Valley. Rocks in the hanging wall of the Blackrock fault are more intensely faulted than rocks in the footwall. The upper plate faults strike north, northwest, east, and northeast. The {approximately}east-striking faults are youngest because they typically cut the other structures. These faults are closely spaced and largely interconnected which allows migration of hydrocarbons. Most of the hanging wall faults are high-angle normal faults which cut both Paleozoic and Oligocene rocks. In the Blackrock upper plate, Paleozoic, carbonate and minor siliciclastic rocks are unconformably overlain by Oligocene tuffs and tuffaceous sedimentary rocks of the Garret Ranch Group with interbedded rhyolites. Upper plate fracturing of the Paleozoic rocks and Garret Ranch Group is important because parts of both sections are producing reservoirs in Railroad Valley.

  10. Effects of a surfactant monolayer on the measurement of equilibrium interfacial tension of a drop in extensional flow.

    PubMed

    González-Mancera, Andrés; Gupta, Vijay Kumar; Jamal, Mustapha; Eggleton, Charles D

    2009-05-15

    The effect of surfactant monolayer concentration on the measurement of interfacial surface tension using transient drop deformation methods is studied using the Boundary Integral Method. Emulsion droplets with a surfactant monolayer modeled with the Langmuir equation of state initially in equilibrium are suddenly subjected to axisymmetric extensional flows until a steady state deformation is reached. The external flow is then removed and the retraction of the drops to a spherical equilibrium shape in a quiescent state is simulated. The transient response of the drop to the imposed flow is analyzed to obtain a characteristic response time, tau(s)( *). Neglecting the initial and final stages, the retraction process can be closely approximated by an exponential decay with a characteristic time, tau(r)( *). The strength of the external flow on each model drop is increased in order to investigate the coupled effect of deformation and surfactant distribution on the characteristic relaxation time. Different model drops are considered by varying the internal viscosity and the equilibrium surfactant concentrations from a surfactant free state (clean) to high concentrations approaching the maximum packing limit. The characteristic times obtained from the simulated drop dynamics both in extension and retraction are used to determine an apparent surface tension employing linear theory. In extension the apparent surface tension under predicts the prescribed equilibrium surface tension. The error increases monotonically with the equilibrium surfactant concentration and diverges as the maximum packing limit is approached. In retraction the apparent surface tension under predicts the prescribed equilibrium surface tension depends non-monotonically on the equilibrium surfactant concentration. The error is highest for moderate surfactant concentrations and decreases as the maximum packing limit is approached. It was found that the difference between the prescribed surface tension

  11. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Technical Reports Server (NTRS)

    Dewit, M. J.

    1986-01-01

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  12. Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

    NASA Astrophysics Data System (ADS)

    Dewit, M. J.

    The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

  13. Extensional Lower Cretaceous volcanism in the Coastal Range (29°20'-30°S), Chile: geochemistry and petrogenesis

    NASA Astrophysics Data System (ADS)

    Morata, D.; Aguirre, L.

    2003-12-01

    Lower Cretaceous volcanism in the Coastal Range (29°20'-30°S) of Chile is mainly represented by highly porphyritic (20-30% phenocrysts) lavas with unzoned Ca-rich plagioclase (An 57-54Ab 40-42Or 3-4), clinopyroxene (Wo 40En 43Fs 17), magnetite, and minor idiomorphic, altered olivines. Geochemically, these lavas are characterized by a relative homogeneity with high Al 2O 3 and low MgO contents, and classified as high-K to shoshonitic basaltic andesites to andesites generated in an intra-arc extensional setting due to oblique subduction. Their isotopic geochemistry is characterized by highly homogeneous low initial Sr ratios (( 87Sr/ 86Sr) 0˜0.7036) and positive ɛNd values ( ɛNd=+2.9 to +4.7 ( 143Nd/ 144Nd) 0˜0.5127) that are very different from those proposed as representative of 'Andean-type' magmatism. A non-Andean modern setting dominated by subduction associated with intra-arc extension is proposed. On a ( 87Sr/ 86Sr) 0 versus ɛNd diagram, these lavas fit a model mixing curve for which the end members are Pacific MORB and Jurassic plutonic rocks from the Coastal Range. Coeval granitoids from the Coastal Range and lavas from the High Andes plot on the same field. Isotopically depleted mafic magmas could be metasomatized by the subducted sediments, which would increase their LILE content, and then partially contaminated by Jurassic plutonic rocks. The genesis of this magmatism may be related to a global low-spreading rate of 5 cm yr -1 in the southeast Pacific during 125-110 Ma.

  14. Tectonic and sequence stratigraphic evolution of asymmetric extensional back-arc basins: seismic interpretations in the Pannonian Basin

    NASA Astrophysics Data System (ADS)

    Balázs, Attila; Matenco, Liviu; Magyar, Imre; Horváth, Ferenc; Cloetingh, Sierd

    2015-04-01

    The evolution of the Pannonian Basin is generally thought to be driven by subduction roll-back associated with mantle flow dynamics. The Miocene back-arc extension resulted in the formation of dominantly half-grabens in the hanging wall of low-angle detachments and listric normal faults, associated with coeval large-scale exhumation of their footwalls. To quantify the evolution of these asymmetric extensional structures, a novel kinematic and seismic sequence stratigraphic interpretation was performed. Based on reflection terminations and characteristic seismic facies we separated systems tracts of the half-graben deposits that formed as a result of interplay between subsidence, sedimentation and water-level variations. Lower order systems tracts were defined by separating rift initiation, rift climax, immediate post-rift and late post-rift systems tracts, while a higher order transgressive-regressive cyclicity and associated unconformities were locally identified in the syn-tectonic basin fill. Connecting these observations demonstrates that extension migrated in time and space across the basin. Extension started during Early Miocene in the oldest sub-basins, while Middle Miocene rift climax is quite common in the entire study area. The youngest syn-tectonic strata were deposited during Late Miocene times in the eastern parts of the Pannonian Basin, for instance, in the Derecske, Makó and Szeged Troughs. The syn-rift/post-rift boundary cannot be interpreted as a discrete event in the entire basin system, because it is a progressive, process-related expression. The obtained results significantly improve the classic ideas of syn-rift/post-rift evolution of the Pannonian Basin.

  15. Comparison of force sensors for atomic force microscopy based on quartz tuning forks and length-extensional resonators

    NASA Astrophysics Data System (ADS)

    Giessibl, Franz J.; Pielmeier, Florian; Eguchi, Toyoaki; An, Toshu; Hasegawa, Yukio

    2011-09-01

    The force sensor is key to the performance of atomic force microscopy (AFM). Nowadays, most atomic force microscopes use micromachined force sensors made from silicon, but piezoelectric quartz sensors are being applied at an increasing rate, mainly in vacuum. These self-sensing force sensors allow a relatively easy upgrade of a scanning tunneling microscope to a combined scanning tunneling/atomic force microscope. Two fundamentally different types of quartz sensors have achieved atomic resolution: the “needle sensor,” which is based on a length-extensional resonator, and the “qPlus sensor,” which is based on a tuning fork. Here, we calculate and measure the noise characteristics of these sensors. We find four noise sources: deflection detector noise, thermal noise, oscillator noise, and thermal drift noise. We calculate the effect of these noise sources as a factor of sensor stiffness, bandwidth, and oscillation amplitude. We find that for self-sensing quartz sensors, the deflection detector noise is independent of sensor stiffness, while the remaining three noise sources increase strongly with sensor stiffness. Deflection detector noise increases with bandwidth to the power of 1.5, while thermal noise and oscillator noise are proportional to the square root of the bandwidth. Thermal drift noise, however, is inversely proportional to bandwidth. The first three noise sources are inversely proportional to amplitude while thermal drift noise is independent of the amplitude. Thus, we show that the earlier finding that quoted an optimal signal-to-noise ratio for oscillation amplitudes similar to the range of the forces is still correct when considering all four frequency noise contributions. Finally, we suggest how the signal-to-noise ratio of the sensors can be improved further, we briefly discuss the challenges of mounting tips, and we compare the noise performance of self-sensing quartz sensors and optically detected Si cantilevers.

  16. Origin and evolution of extensional faults within the ductile-to-brittle transition, Badwater Turtleback, Death Valley, CA

    SciTech Connect

    Miller, M.G. . Geological Sciences)

    1992-01-01

    Field relations in the footwall of the Badwater Turtleback suggest a model for two geometrically distinct sets of brittle faults. The model shows how extensional brittle faults may (1) initiate within mylonite zones as a result of strain incompatibilities, and (2) become inactive as a function of decreased dip angles. Cross-cutting relations indicate that, as the footwall cooled, late stages of ductile strain concentrated in calcite marble shear zones while brittle faults formed within the other rocks. These faults fall into two groups: decollement-style faults (DSF) and high angle faults (HAF). They must have formed concurrently with calcite mylonitization because they locally terminate at the calcite shear zones. DSF are subparallel to mylonitic foliation and locally re-occupy calcite shear zones. They are moderately nonplanar, discontinuous at scales of 10--100m, and show limited evidence for transport parallel to stretching lineations in adjacent mylonites. HAF cut foliation at high angles. These faults either (1) end downwards into unfractured calcite mylonite, (2) cut calcite mylonite and join underlying DSF, or (3) cut calcite mylonite and DSF. Where they join DSF, HAF are strongly listric and maintain integrity as distinct slip surfaces within the DSF zone (see inset). DSF formed at rheological boundaries and at places where actively deforming calcite marble pinched out into brittle rocks. HAF formed in brittle upper plates of calcite marble shear zones to accommodate differences in strain between brittle and nonbrittle rock. With continued strain and consequent cooling and eastward tilting of the footwall, calcite shear zones stopped deforming ductility, became occupied by DSF, and gradually rotated to lower angles.

  17. Heat flow in the Basin and Range province and thermal effects of tectonic extension

    USGS Publications Warehouse

    Lachenbruch, A.H.

    1978-01-01

    In regions of tectonic extension, vertical convective transport of heat in the lithosphere is inevitable. The resulting departure of lithosphere temperature and thickness from conduction-model estimates depends upon the mechanical mode of extension and upon how rapidly extension is (and has been) taking place. Present knowledge of these processes is insufficient to provide adequate constraints on thermal models. The high and variable regional heat flow and the intense local heat discharge at volcanic centers in the Basin and Range province of the United States could be accounted for by regional and local variations in extensional strain rate without invoking anomalous conductive heat flow from the asthenosphere. Anomalous surface heat flow typical of the province could be generated by distributed extension at average rates of about 1/2 to 1%/m.y., similar to rates estimated from structural evidence. To account for higher heat flow in subregions like the Battle mountain High, these rates would be increased by a factor of about 3, and locally at active bimodal volcanic centers, by an order of magnitude more. ?? 1978 Birkha??user Verlag.

  18. Distribution and diversity of sulfur-oxidizing Thiomicrospira spp. at a shallow-water hydrothermal vent in the Aegean Sea (Milos, Greece).

    PubMed

    Brinkhoff, T; Sievert, S M; Kuever, J; Muyzer, G

    1999-09-01

    A shallow-water hydrothermal vent system in the Aegean Sea close to the island of Milos (Greece) was chosen to study the diversity and distribution of the chemolithoautotrophic sulfur-oxidizing bacterium Thiomicrospira. Cell numbers in samples from different regions around a solitary vent decreased toward the center of the vent (horizontal distribution), as well as with depth (vertical distribution), corresponding to an increase in temperature (from ca. 25 to 60 degrees C) and a decrease in pH (from ca. pH 7 to 5). Thiomicrospira was one of the most abundant culturable sulfur oxidizers and was even dominant in one region. Phylogenetic analysis of Thiomicrospira spp. present in the highest most-probable-number (MPN) dilutions revealed that most of the obtained sequences grouped in two new closely related clusters within the Thiomicrospira branch. Two different new isolates, i.e., Milos-T1 and Milos-T2, were obtained from high-dilution (10(-5)) enrichments. Phylogenetic analysis indicated that isolate Milos-T1 is related to the recently described Thiomicrospira kuenenii and Hydrogenovibrio marinus, whereas isolate Milos-T2 grouped with the MPN sequences of cluster 2. The predominance of strain Milos-T2 was indicated by its identification in several environmental samples by hybridization analysis of denaturing gradient gel electrophoresis (DGGE) patterns and by sequencing of one of the corresponding bands, i.e., ML-1, from the DGGE gel. The results shown in this paper support earlier indications that Thiomicrospira species are important members of hydrothermal vent communities.

  19. Wild fire effects on floristic diversity in three thermo-Mediterranean vegetation types in a small islet of eastern Aegean sea

    NASA Astrophysics Data System (ADS)

    Abraham, Eleni; Kyriazopoulos, Apostolos; Korakis, George; Parissi, Zoi; Chouvardas, Dimitrios

    2014-05-01

    Sclerophyllus scrub formations, the main vegetation type in many islands of the Aegean area, are characterized by their high biodiversity. Dominant shrub species of sclerophyllus formations are well adapted to dry season conditions by various anatomical and physiological mechanisms. As a result, their biomass acts as very flammable fine fuel, and consequently wild fires are very common in these ecosystems. Wildfire effects on vegetation and biodiversity in the Mediterranean basin have been studied and the results are diverse depending mainly on vegetation type and frequency of fire. The aim of this study was to evaluate the effects of wildfire on floristic diversity and species composition in three thermo-Mediterranean vegetation types 1) Sacropoterium spinosum phrygana, 2) low formations of Cistus creticus and 3) low formations of Cistus creticus in abandoned terraces. The research was conducted in Enoussa islet, which is located northeastern of Chios Island, in May 2013 (one year after the fire). Vegetation sampling was performed along five transects placed in recently burned and in adjacent unburned sites of each vegetation type. The plant cover and the floristic composition were measured, while diversity, evenness and dominance indices were determined for the vegetation data. Vegetation cover and the floristic diversity were significant lower and higher respectively in burned areas in comparison to the unburned. The woody species followed by the annual grasses and the annual forbs dominated in both burned and unburned areas. However, the woody species were significantly decreased in the burned areas in all vegetation types, while the annual grasses only in the burned areas of Sacropoterium spinosum phrygana and Cistus creticus in abandoned terraces. Inversely, the annual forbs significantly increased in the burned sites of Cistus creticus formations. The highest value of Morisita-Horn Index of similarity between burned and unburned sites (beta diversity) was

  20. Tracing organic and inorganic pollution sources of agricultural crops and water resources in Güzelhisar Basin of the Aegean Region - Turkey

    NASA Astrophysics Data System (ADS)

    Czarnecki, Sezin; Colak Esetlili, Bihter; Esetlili, Tolga; Tepecik, Mahmut; Anac, Dilek; Düring, Rolf-Alexander

    2014-05-01

    The study area Güzelhisar Basin is 6 km far from the city Aliaga, Aegean Region in Turkey which represents a rather industrialized area having five large iron and steel factories, but also areas of agriculture. Steel industry in Aliaga is causing metal pollution. Around Güzelhisar Basin and nearby, the dominant crop fields are cotton, maize, vegetables, olive trees and vineyards. Güzelhisar stream and dam water is used for irrigation of the agricultural land. Due to contamination from metal industry in Aliaga, organic farming is not allowed in this region. Industrial activities in the region present a threat on sustainable agriculture. The region is a multi-impacted area in terms of several pollutant sources affecting soil and water quality. The overall objective of the project is to trace back plant nutrients (N, P, K, Ca, Mg, Na, Fe, Mn, Zn, Cu, and B), hazardous substances (i. e. persistent organic pollutants), radionuclides (40K, 232Th, 226Ra/238U), and metal contents (As, Cd, Cr, Co, Cu, Hg, Mn, Ni, Pb, and Zn) by examining the soils, agricultural crops and natural plants from Güzelhisar Basin and water and sediments from Güzelhisar stream and dam. Spatial distribution of pollution will be evaluated by regionalization methods. For this, an advanced analytical methodology will be applied which provides an understanding of sources and occurrence of the respective substances of concern. An innovative multi-tracer approach comprising organic and inorganic marker substances, will identify and quantitatively assess sources and their impact on water pollution and the pollutant pathways in this agricultural crop production system.

  1. Interaction between regional and local tectonic forcing along a complex Quaternary extensional basin: Upper Tiber Valley, Northern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Pucci, S.; Mirabella, F.; Pazzaglia, F.; Barchi, M. R.; Melelli, L.; Tuccimei, P.; Soligo, M.; Saccucci, L.

    2014-10-01

    In extending areas undergoing regional tectonic uplift, the persistence of subsidence at a normal-fault hanging-wall depends on the competition between regional and local tectonic effects. When regional uplift exceeds the subsidence of the hanging-wall block, denudation prevails at both the hanging-wall and the foot-wall. When local tectonic subsidence exceeds regional uplift, sedimentation occurs over the hanging-wall block, supplied by foot-wall erosion. We analyzed a Pliocene-Quaternary continental basin, currently crossed by the Tiber River in Italy. The tectono-sedimentary evolution of the basin developed at the hanging-wall of a regional low-angle extensional detachment, the Alto Tiberina Fault, in the axial region of the Northern Apennines of Italy. This area is affected by regional uplift on the order of 0.5-1.0 mm/yr. The present-day activity of the fault is revealed by both microseismicity and geodetic (GPS) data. We investigated the mid- (10-100 ka) and long-term (0.5-3.0 Ma) evolution of the three depocenters by studying the continental Pleistocene succession infilling the basin as well as fluvial terraces and higher paleosurfaces carved into the Pleistocene deposits. By using surficial geologic data and an interpretation of a set of seismic reflection profiles, we show that the three depocenters experienced a fairly similar evolution during the Pliocene-Early Pleistocene, when a 1000-m-thick continental succession was deposited. On the contrary, geomorphological observations indicate that, at the beginning of the Middle Pleistocene, a switch occurred in the evolution of the three depocenters. In the northernmost Sansepolcro sub-basin, bounding normal faults are active and hanging-wall subsidence outpaces regional uplift. Concurrently, in the Umbertide and Ponte Pattoli sub-basins uplift dominates over the hanging-wall subsidence, promoting river incision and exhumation of the Pleistocene deposits. For these two depocenters, by means of terrace

  2. Thermal history and extensional exhumation of a high-temperature crystalline complex (Hırkadağ Massif, Central Anatolia)

    NASA Astrophysics Data System (ADS)

    Lefebvre, Côme; Kalijn Peters, M.; Wehrens, Philip C.; Brouwer, Fraukje M.; van Roermund, Herman L. M.

    2015-12-01

    The Central Anatolian Crystalline Complex (CACC) is a large continental domain exposed in central Turkey that was affected by high temperature metamorphism during the Late Cretaceous. As a result of this event, Paleozoic sediments became metamorphosed, initially under Barrovian conditions, then overprinted locally by high temperature-low pressure metamorphism, and intruded by widespread batholiths. In this study we focus on the crystalline Hırkadağ Massif located in the central part of the CACC, where we applied an integrated approach involving metamorphic, structural and geochronological analysis in order to elucidate its tectonic history from burial to exhumation. Our metamorphic study reveals that conditions of metamorphism reached ~ 7-8 kbar/700 °C and were relatively homogeneous at the scale of the Hırkadağ Massif. Coeval with the regional metamorphism, the rocks were intensely deformed as reflected by isoclinal folding, the development of a pervasive foliation and top-to-the-SE shearing. This was followed by decompression to pressures of ~ 3-4 kbar at 800 °C, which may be linked to the emplacement of local granodioritic intrusions at ~ 77 Ma. Subsequent cooling of the Hırkadağ high-grade metamorphic and intrusive rocks is indicated by 40Ar/39Ar cooling ages of 68.8 ± 0.9 Ma (biotite) and 67.0 ± 1.2 Ma (potassium feldspar). Evidence for tectonic exhumation has been identified within the marbles at the NE margin of the Hırkadağ Massif, in the form of discrete protomylonitic and mylonitic shear bands showing a consistent N40-60 top-to-NE sense of shear. Further east, the contact between brecciated mylonitic marbles and non-metamorphic conglomerates preserves the typical structural features of an upper-crustal detachment fault. Restoration of the Hırkadağ Massif and the CACC to their late Cretaceous configuration suggests that the LP-HT metamorphism, magmatism and extensional structures evolved as a result of the development and exhumation of a ~ N

  3. The tectonic evolution of Cenozoic extensional basins, northeast Brazil: Geochronological constraints from continental basalt 40Ar/39Ar ages

    NASA Astrophysics Data System (ADS)

    de Souza, Zorano Sérgio; Vasconcelos, Paulo Marcos; Knesel, Kurt Michael; da Silveira Dias, Luiz Gustavo; Roesner, Eduardo Henrique; Cordeiro de Farias, Paulo Roberto; de Morais Neto, João Marinho

    2013-12-01

    The Boa Vista and Cubati Basins, Paraíba, Brazil, are NW-SE extension-related intracratonic basins that resulted from tectonic stresses after the opening of the South Atlantic. These basins contain lacustrine fossiliferous sediments, bentonite beds, and basalt flows that preserve Cenozoic continental records. 40Ar/39Ar ages for six whole-rocks from two distinct basaltic flows underlying the sediments in the Boa Vista basin are 27.3 ± 0.8 and 25.4 ± 1.3 Ma, while three grains from a basaltic flow overlying the sediments yield 22.0 ± 0.2 Ma. The sediments at the nearby Cubati Basin are overlain by a basalt flow with ages of ˜25.4 Ma. Three whole-rocks from an NE-SW-trending trachytic dyke cross cutting the sediments at the Boa Vista Basin yield 40Ar/39Ar ages of ˜12.45 ± 0.06, 12.59 ± 0.07, and 12.58 ± 0.07 Ma. Three whole-rocks from a nearby volcanic plug (Chupador) yield an age of 23.4 ± 0.1 Ma. The geochronological results combined with stratigraphic correlations between the two basins allow bracketing the age of the main sedimentary and bentonic units within the Boa Vista and Cubati Basins between 25.5 ± 1.3 and 24.9 ± 0.1 Ma. The ages, combined with field observations reveal that the formation of the Boa Vista and Cubati basins is associated with mantle-derived magmas channelled through reactivated Precambrian shear zones. Our geochronological results suggest that a temporal link with the Fernando de Noronha and Saint Helena hot spots can be excluded as possible sources of the Boa Vista and Cubati magmas. Rather, the extensional tectonics in the 30-20 Ma interval, long after Gondwana break-up, may be associated with the re-activation of continental-scale shear zones that channelled small batches of mantle-derived magmas.

  4. Extensional to compressive Mesozoic magmatism at the SE Eurasia margin as recorded from the Meratus ophiolite (SE Borneo, Indonesia)

    NASA Astrophysics Data System (ADS)

    Monnier, Christophe; Polvé, Mireille; Girardeau, Jacques; Pubellier, Manuel; Maury, René C.; Bellon, Hervé; Permana, Haryadi

    1999-01-01

    The Meratus ophiolitic series (SE Borneo) present a specific assemblage that have recorded (1) a continental extensional episode mostly seen within the peridotites and 2) later subduction-related magmatic events marked by the emplacement of calc-alkaline magmas. These events relate the magmatic activity and geodynamic evolution of the SE Eurasia margin in Mesozoic times. The ophiolitic series comprise ultramafic rocks with minor metavolcanic rocks. The ultramafic rocks include dominant lherzolites and pyroxenites with rather scarce harzburgites and dunites. Spinel peridotite, mineral chemistry data and bulk rock Rare Earth Element (REE) abundances show that most rocks underwent a low degree of partial melting. However, a few samples display significant depletions in Light REE (LREE), which are interpreted as the result of fractional melting under shallow conditions. Plagioclase-bearing peridotites are characterized by high REE abundances which also point to a very low degree of melting followed by reequilibration in the plagioclase facies, as seen from phase chemistry data. These peridotites are locally crosscut by dikelets containing high-temperature K-and Cr-rich amphiboles. Lavas closely associated with the Meratus peridotites have REE compositions ranging from the ones typical of enriched MORB (E-MORB) to normal MORB (N-MORB) types. We believe that the Meratus peridotites represent a fragment of subcontinental lithospheric mantle that locally suffered a low degree of fractional melting during the last stages of a continental rifting phase, in agreement with the presence of metamorphic K- and Cr-rich amphiboles in the peridotites. The E-MORB basalts might result from the melting of an enriched subcontinental lithosphere thermally eroded during the rifting phase by rising asthenosphere which might have produced N-MORB volcanic rocks. Back-arc basin basalts (BABB) now associated with E-MORB and N-MORB have also been found in the metamorphic soles of the

  5. Evolution of an Interbasin Mountain-Block Extensional Accommodation Zone Within the Central Colorado Rio Grande Rift, USA

    NASA Astrophysics Data System (ADS)

    Minor, S. A.; Caine, J. S.; Fridrich, C.; Hudson, M. R.

    2015-12-01

    Our understanding of extensional strain transfer and accommodation in continental rifts has grown considerably, but few studied transfer zones exhibit high internal topographic and structural relief. In the Rio Grande rift of Colorado the WNW-trending northern tip of the Sangre de Cristo Range separates the opposite-tilted Upper Arkansas River (UAR) and San Luis half grabens. We have investigated the development and role of faults flanking this "Poncha" intrarift mountain block in transferring extension between rift basins, mountain block surface uplift, and landscape evolution. The topographically rugged Poncha block consists of Proterozoic metamorphic and plutonic rocks overlain on its west and southwest flanks by 34.5-33-Ma volcanic rocks and alluvial deposits of the Mio-Pliocene Dry Union Formation. Similar Dry Union sediments underlie a moderately elevated, strongly dissected older piedmont along the northern front of the mountain block. All of these units are tilted 10-35º to the W and SW. A WNW-trending, right-stepping fault system > 25 km in length separates the piedmont and UAR basin from the steep northern Poncha mountain front. Slip measurements along this fault system, cutting deposits as young as ~200 ka, indicate dextral-normal oblique movement. The NNW-striking, down-to-E southern Sawatch range-front fault system forms the western terminus of the Poncha block where it juxtaposes Dry Union deposits against Sawatch Proterozoic basement rocks. Gently tilted proximal diamicton and alluvial deposits on the downthrown blocks of both range-front faults likely mark Plio-Pleistocene(?) mountain block uplift. Arrays of NNW- to WNW-striking faults cutting volcanic and Dry Union units on the flanks of the Poncha block commonly have normal-oblique slip, with greater tendency for dextral strike-slip components on WNW-striking faults. Preliminary paleomagnetic data from the volcanic rocks detect no significant vertical-axis rotation that accompanied oblique

  6. Quaternary extensional and compressional tectonics revealed from Quaternary landforms along Kosi River valley, outer Kumaun Lesser Himalaya, Uttarakhand

    NASA Astrophysics Data System (ADS)

    Luirei, Khayingshing; Bhakuni, S. S.; Kothyari, Girish Ch.; Tripathi, Kavita; Pant, P. D.

    2016-04-01

    A portion of the Kosi River in the outer Kumaun Lesser Himalaya is characterized by wide river course situated south of the Ramgarh Thrust, where huge thickness (~200 m) of the landslide deposits and two to three levels of unpaired fan terraces are present. Brittle normal faults, suggesting extensional tectonics, are recognized in the Quaternary deposits and bedrocks as further supported by surface morphology. Trending E-W, these faults measure from 3 to 5 km in length and are traced as discontinuous linear mini-horst and fault scarps (sackungen) exposed due to cutting across by streams. Active normal faults have displaced the coarsely laminated debris fan deposits at two sites located 550 m apart. At one of the sites, the faults look like bookshelf faulting with the maximum displacement of ~2 m and rotation of the Quaternary boulders along the fault plane is observed. At another site, the maximum displacement measures about 0.60 cm. Thick mud units deposited due to blocking of the streams by landslides are observed within and above the fan deposit. Landslide debris fans and terrace landforms are widely developed; the highest level of fan is observed ~1240 m above mean sea level. At some places, the reworking of the debris fans by streams is characterized by thick laminated sand body. Along the South Almora Thrust and Ramgarh Thrust zones, the valleys are narrow and V-shaped where Quaternary deposits are sparse due to relatively rapid uplift across these thrusts. Along the South Almora Thrust zone, three to four levels of fluvial terraces are observed and have been incised by river exposing the bedrocks due to recent movement along the RT and SAT. Abandoned channel, tilted mud deposits, incised meandering, deep-cut V-shaped valleys and strath terraces indicate rapid uplift of the area. Thick mud sequences in the Quaternary columns indicate damming of streams. A ~10-km-long north-south trending transverse Garampani Fault has offset the Ramgarh Thrust producing

  7. Extensional Tectonics and Paleoclimate of the Albertine and Edward Rifts: Constraints from Integrated Seismic Reflection and Topographic Studies

    NASA Astrophysics Data System (ADS)

    Karp, T.; McGlue, M. M.; Scholz, C. A.; Kasande, R.; Mugisha, F.

    2004-12-01

    Lakes Albert and Edward are among the largest lakes in Africa and form substantial reservoirs for tropical precipitation within the Upper Nile Watershed (UNW), the equatorial headwaters supporting annual discharge of the main Nile River into the Mediterranean Sea. Extensional processes forming Lakes Albert and Edward have driven landscape evolution, manifested in significant topography and reversed drainages networks. Consequently, the UNW, including Lakes Albert, Edward, Victoria, and Kyoga, and their riverine connections, provide an important case study for drainage basin evolution in actively extending continental lithosphere. In addition to multiple scales of tectonic deformation, high frequency climate change affects the basins in the UNW, which record moisture signals from both the Indian and Atlantic Oceans. Paleoclimate proxy data indicate the desiccation of Lake Victoria and cessation of Victoria Nile flow during the Last Glacial Maximum (22 - 18 ka). However, the response of Lakes Albert and Edward during this time period is not fully resolved. In 2003, 1600 line km of multichannel seismic reflection and high resolution echo-sounder data were collected from Lake Albert, while 200 km of 1 kHz seismic reflection data were collected from Lake Edward. In conjunction with recently released digital elevation models, we investigate both tectonic and climatic processes operative in the basins. In Lake Albert, we are able to map depth to pre-rift basement, basin boundary fault as well as intrabasinal fault geometries that control both bathymetry and sediment distribution. Shallow reflections suggest desiccation of the lake, probably during the LGM; these results tie well with published sediment core data. Acoustic data from Lake Edward record two regression events, although this lake apparently escaped LGM desiccation, and may contain a complete, high-resolution archive of Quaternary climate change in its deep-water sequences. Our interpretations provide another

  8. Seismic slip at the base of the seismogenic layer along the exhumed extensional Oligocene Trois Villes Fault (Western Italian Alps)

    NASA Astrophysics Data System (ADS)

    Bistacchi, A.; Gatta, D.; Grizzetti, R.; Pennacchioni, G.

    2008-12-01

    The characterisation of fault rocks from exhumed faults is of paramount importance in fault and earthquake mechanics, since these rocks might provide constraints for models of seismic rupture initiation and propagation. The Trois Ville Fault is a major Oligocene extensional fault of the internal NW Alps, showing a cumulative displacement of c.a. 1 km evidenced by the offset boundary between Austroalpine gneisses (hangingwall) and Piedmont calcschists (footwall). Fault rocks consist of greenschist mylonitic gneiss (from an early stage), green indurated cataclasites, which constitute the 2-10 m thick core zone, and a thin (c.a. 10 cm) but extremely continuous layer of polycyclic pseudotachylytes which mark a strongly localised principal slipping zone. Pseudotachylytes lack distinctive features such as glass, microlites-spherulites, etc., but show a distinctive mineralogy of the melt-derived very fine-grained matrix, which is almost entirely constituted by monoclinic K-feldspar (low sanidine crystallised at ca. 990°C and partly ordered as far as 500- 700°C). This matrix is composed by very small crystals (0.5-5 μm), organised in aggregates and dendritic snowflake-like aggregates which might be explained by sintering or synneusis processes. The high crystallization T implies that pseudotachylytes derive from frictional melting of ultracataclasites (possibly incoherent, hence a fault gouge, at the time of deformation) near the brittle plastic transition (250- 300°C and 8-10 km). Hence, a new diagnostic criterion for frictional melting, based on crystallographic analysis, is introduced in this work. The melt mainly derived from phyllosilicates (muscovite and minor chlorite; Tmelt c.a. 750°C) and evidences of superheating may be envisaged (partial assimilation of albite and quartz; T > c.a. 1300°C). This points to a considerable seismic slip after the onset of frictional melting and to an efficient melting lubrication process in this kind of fault rocks

  9. Shortening in the upper plate of the Buckskin-Rawhide extensional detachment fault, southwestern U.S., and implications for stress conditions during extension

    NASA Astrophysics Data System (ADS)

    Spencer, Jon E.; Reynolds, Stephen J.; Scott, Robert J.; Richard, Stephen M.

    2016-12-01

    Detailed geologic mapping in the Buckskin, Rawhide, and Artillery Mountains in western Arizona identified numerous folds in Oligocene-Miocene strata above the Buckskin-Rawhide extensional detachment fault. The folds are above or adjacent to the Harcuvar metamorphic core complex, which was uplifted and exposed by top-northeast normal faulting and penetrative shearing at 27-9 Ma. Strata deposited during extension were folded, and the folds are truncated by the detachment fault, demonstrating that folding occurred during the period of extensional faulting. Fold axes are approximately perpendicular to regional extension direction. In two of the four areas of folding described here, alluvial-fan deposits derived partially from lower plate mylonitic rocks are the stratigraphically highest folded strata. Folding could have occurred above low-angle normal faults with curved or ramp-flat geometries, but fold abundance, large size, high degree of closure, and steep northeastward dips of the northeast limbs of anticlines lead us to consider the possibility that at least some folds reflect local shortening in the same direction as regional extension. Application of critical-taper theory to an extensional wedge with very low basal friction indicates that wedge shortening would be expected if the wedge developed a sufficient surface slope that was downhill away from the wedge tip. Such a slope could have developed late during extension either because core-complex uplift tilted the wedge away from the core complex or because alluvial fans shed off the core complex produced such a slope. In either case, wedge shortening would promote core-complex denudation.

  10. The role of salt layers in the hangingwall deformation of kinked-planar extensional faults: Insights from 3D analogue models and comparison with the Parentis Basin

    NASA Astrophysics Data System (ADS)

    Ferrer, O.; Roca, E.; Vendeville, B. C.

    2014-12-01

    Using an analogue modelling approach, this work investigates the role played by salt in the hangingwall deformation of an extensional fault. Models' set-up included a wooden block simulating the footwall of different kinked-planar fault geometries flattening at depth. Above these faults, the hangingwall was modelled using only sand or sand overlain by pre- or syn-kinematic silicone putty. Regardless of the stage at which was deposited, the silicone appears as an efficient decoupling level that changes the deformation mode of the overlying sand layers. Above the silicone layers, the rollover panels only continue to develop up to the welding of the underlying silicone. Afterwards, they do not grow anymore and all shearing induced by the underlying fault bends is accommodated along the tilted silicone layer that acts as an extensional shear band. Further fault slip produces near-horizontal growth stratal geometries that can be easily misinterpreted as a syn-rift/post-rift boundary. In addition, the differential sedimentary loading of syn-kinematic layers triggers the upslope silicone flow from the hangingwall depocenters towards the rollover shoulders. This migration results in the formation of silicone welds at the rollover limbs and the growth of gentle silicone-cored anticlines above or near the rollover shoulder that are locally pierced by diapirs and walls. These experimental results fit with the Parentis Basin structure that, formed from the motion of lithosphere-scale kinked-planar extensional faults, includes salt inflated anticlines above their rollover shoulders and an intra-Albian unconformity interpreted now as syn-kinematic.

  11. Neotectonic deformation within an extensional stepover in El Salvador magmatic arc, Central America: Implication for the interaction of arc magmatism and deformation

    NASA Astrophysics Data System (ADS)

    Garibaldi, Nicolás; Tikoff, Basil; Hernández, Walter

    2016-12-01

    Dominantly westward movement of the El Salvador forearc at rates of 11 mm/yr is accommodated by a series of E-W to WNW oriented, dextral, strike-slip fault zones herein referred to as the El Salvador Fault System (ESFS). The geometry of the ESFS defines a series of extensional step-overs. Along the arc, basaltic volcanism in the stepovers is associated with NNW-oriented normal faults, whereas rhyolitic volcanism is associated with strike-slip fault zones of the ESFS. On the ESFS, the San Salvador Extensional Stepover (SSES) is bound to the south by the San Vicente fault zone, where the rhyolitic Ilopango caldera is located. In the SSES, tephras from Ilopango -the Tierra Blanca (TB) sequence- track long-term elongation. Older TB units (TB5-8) contain abundant normal faults; lying unconformably above these older TB units, younger TB members (TBJ, TB2-4) are generally unfaulted. Analyses of faults in TB5-8 indicate NE- to ENE-oriented elongation in the SSES. Deformation occurred between deposition of the TB4 and TB5 units, during quiescence of the Ilopango eruptive center. Using this temporal constraint, minimum elongation rates of 3.50 × 10- 15 s- 1, 2.06 × 10- 14 s- 1 and 4.42 × 10- 14 s- 1 were calculated for three traverses. From regional geodetic data and fault kinematics throughout El Salvador, we interpret the SSES as part of a series of pull-apart structures along the arc axis. The calculated paleostress orientations are consistent with a pull-apart geometry resulting from forearc movement. The extensional deformation occurs during a 50 k.y. lull in rhyolitic activity, suggesting an interplay between magmatism and deformation within the arc. During significant rhyolitic volcanic activity, only minor elongation is observed in the SSES, despite ongoing translation of the Salvadoran forearc. We speculate that rhyolitic magmatism along upper crustal faults may facilitate strike-slip movement on the ESFS, rather than distributing deformation throughout the

  12. Extensional orogenic collapse captured by strike-slip tectonics: Constraints from structural geology and Usbnd Pb geochronology of the Pinhel shear zone (Variscan orogen, Iberian Massif)

    NASA Astrophysics Data System (ADS)

    Fernández, Rubén Díez; Pereira, Manuel Francisco

    2016-11-01

    The late Paleozoic collision between Gondwana and Laurussia resulted in the polyphase deformation and magmatism that characterizes the Iberian Massif of the Variscan orogen. In the Central Iberian Zone, initial continental thickening (D1; folding and thrusting) was followed by extensional orogenic collapse (D2) responsible for the exhumation of high-grade rocks coeval to the emplacement of granitoids. This study presents a tectonometamorphic analysis of the Trancoso-Pinhel region (Central Iberian Zone) to explain the processes in place during the transition from an extension-dominated state (D2) to a compression-dominated one (D3). We reveal the existence of low-dipping D2 extensional structures later affected by several pulses of subhorizontal shortening, each of them typified by upright folds and strike-slip shearing (D3, D4 and D5, as identified by superimposition of structures). The D2 Pinhel extensional shear zone separates a low-grade domain from an underlying high-grade domain, and it contributed to the thermal reequilibration of the orogen by facilitating heat advection from lower parts of the crust, crustal thinning, decompression melting, and magma intrusion. Progressive lessening of the gravitational disequilibrium carried out by this D2 shear zone led to a switch from subhorizontal extension to compression and the eventual cessation and capture of the Pinhel shear zone by strike-slip tectonics during renewed crustal shortening. High-grade domains of the Pinhel shear zone were folded together with low-grade domains to define the current upright folded structure of the Trancoso-Pinhel region, the D3 Tamames-Marofa-Sátão synform. New dating of syn-orogenic granitoids (SHRIMP Usbnd Pb zircon dating) intruding the Pinhel shear zone, together with the already published ages of early extensional fabrics constrain the functioning of this shear zone to ca. 331-311 Ma, with maximum tectonomagmatic activity at ca. 321-317 Ma. The capture and apparent cessation

  13. Anisotropy of Magnetic Susceptibility (AMS) of the Neogene Volcanic Succession at the Sierra Juarez - Las PintasVolcanic Province, Northeastern Baja California, Mexico: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Mendoza-Borunda, R.; Cañón-Tapia, E.; Suárez-Vidal, F.; Gradilla-Martínez, L.

    2010-12-01

    The Sierra Juarez-Las Pintas Volcanic Province is among the largest in northern Baja California. For this work, we focused on a bimodal volcanic succession of late Miocene age, composed of an extensive ignimbrite unit and few dispersed basaltic flows that crop out in central Sierra Juarez and northern Sierra Las Tinajas. The ignimbrite is zoned, composed by three distinctive members: a basal unwelded white tuff, a mid-section unwelded orange tuff, and an upper red welded tuff. The basaltic flows are olivine-rich. Samples were collected in five sites that define a NE-SW section across the Sierra Juarez Escarpment, in the western boundary of the so-called Gulf Extensional Province. In each of these sites a stratigraphic column composed of more than one geologic unit was sampled. The total number of analyzed cores is ca. 160. The preliminary results show vertical and lateral variations of the AMS of the ignimbrite that can be interpreted in terms of the local flow direction and processes of emplacement of these volcanic deposits. Such variations, in turn, are likely to reflect variations in the dynamics of the eruptive process that produced them. Although the AMS of all the rocks in this province display a complex set of orientations, in this work is shown that when examined in detail important clues concerning the geological evolution of the province can be obtained from these data.

  14. Fore arc tectonothermal evolution of the El Oro metamorphic province (Ecuador) during the Mesozoic

    NASA Astrophysics Data System (ADS)

    Riel, Nicolas; Martelat, Jean-Emmanuel; Guillot, Stéphane; Jaillard, Etienne; Monié, Patrick; Yuquilema, Jonatan; Duclaux, Guillaume; Mercier, Jonathan

    2014-10-01

    The El Oro metamorphic province of SW Ecuador is a composite massif made of juxtaposed terranes of both continental and oceanic affinity that has been located in a fore-arc position since Late Paleozoic times. Various geochemical, geochronological, and metamorphic studies have been undertaken on the El Oro metamorphic province, providing an understanding of the origin and age of the distinct units. However, the internal structures and geodynamic evolution of this area remain poorly understood. Our structural analysis and thermal modeling in the El Oro metamorphic province show that this fore-arc zone underwent four main geological events. (1) During Triassic times (230-225 Ma), the emplacement of the Piedras gabbroic unit at crustal-root level (~9 kbar) triggered partial melting of the metasedimentary sequence under an E-W extensional regime at pressure-temperature conditions ranging from 4.5 to 8.5 kbar and from 650 to 900°C for the migmatitic unit. (2) At 226 Ma, the tectonic underplating of the Arenillas-Panupalí oceanic unit (9 kbar and 300°C) thermally sealed the fore-arc region. (3) Around the Jurassic-Cretaceous boundary, the shift from trench-normal to trench-parallel subduction triggered the exhumation and underplating of the high-pressure, oceanic Raspas Ophiolitic Complex (18 kbar and 600°C) beneath the El Oro Group (130-120 Ma). This was followed by the opening of a NE-SW pull-apart basin, which tilted the massif along an E-W subhorizontal axis (110 Ma). (4) In Late Cretaceous times, an N-S compressional event generated heterogeneous deformation due to the presence of the Cretaceous Celica volcanic arc, which acted as a buttress and predominantly affected the central and eastern part of the massif.

  15. Kimmeridgian Shales Total Petroleum System of the North Sea Graben Province

    USGS Publications Warehouse

    Gautier, Donald L.

    2005-01-01

    The North Sea Graben of northwestern Europe, World Energy Project Province 4025, is entirely offshore within the territorial waters of Denmark, Germany, the Netherlands, Norway, and the United Kingdom. Extensional tectonics and failed rifting are fundamental to the distribution of oil and gas in the province. Accordingly, the geologic history and reser-voir rocks of the province are considered in the context of their temporal relationship to the principal extension and rifting events. The oil and gas accumulations of the province are considered part of a single petroleum system: the Kimmeridg-ian Shales Total Petroleum System (TPS). Source rocks of the Kimmeridgian Shales TPS were deposited in Late Jurassic to earliest Cretaceous time during the period of intensive exten-sion and rifting. The Kimmeridgian Shales contain typical 'type II' mixed kerogen. Oil and gas generation began locally in the North Sea Graben Province by Cretaceous time and has continued in various places ever since. Reservoirs are found in strata with ages ranging from Devonian to Eocene. Pre-rift reservoirs are found in fault-block structures activated during rifting and can be of any age prior to the Late Jurassic. Syn-rift reservoirs are restricted to strata actually deposited during maximum extension and include rocks of Late Jurassic to earliest Cretaceous age. Post-rift reservoirs formed after rifting and range in age from Early Cretaceous to Eocene. Seals are diverse, depending upon the structural setting and reservoir age. Pre-rift reservoirs com-monly have seals formed by fine-grained, post-rift sedimentary sequences that drape the Late Jurassic to earliest Cretaceous structures. Contemporaneous shales such as the Kimmeridge Clay seal many syn-rift reservoirs. Fields with post-rift res-ervoirs generally require seals in fine-grained Tertiary rocks. In most of the North Sea Graben, source rocks have been continuously buried since deposition. Structural trap forma-tion has also taken

  16. New boron isotopic evidence for sedimentary and magmatic fluid influence in the shallow hydrothermal vent system of Milos Island (Aegean Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Wu, Shein-Fu; You, Chen-Feng; Lin, Yen-Po; Valsami-Jones, Eugenia; Baltatzis, Emmanuel

    2016-01-01

    Magmatic sources may contribute a significant amount of volatiles in geothermal springs; however, their role is poorly understood in submarine hydrothermal systems worldwide. In this study, new results of B and δ11B in 41 hydrothermal vent waters collected from the shallow hydrothermal system of Milos island in the Aegean Sea were combined with previously published data from other tectonic settings and laboratory experiments to quantify the effects of phase separation, fluid/sediment interaction and magmatic contribution. Two Cl-extreme solutions were identified, high-Cl waters (Cl as high as 2000 mM) and low-Cl waters (Cl < 80 mM). Both sets of waters were characterized by high B/Cl (~ 1.2-5.3 × 10- 3 mol/mol) and extremely low δ11B (1.4-6.3‰), except for the waters with Mg content of near the seawater value and δ11B = 10.3-17.4‰. These high-Cl waters with high B/Cl and low δ11B plot close to the vent waters in sediment-hosted hydrothermal system (i.e., Okinawa Trough) or fumarole condensates from on-land volcanoes, implying B addition from sediment or magmatic fluids plays an important role. This is in agreement with fluid/sediment interactions resulting in the observed B and δ11B, as well as previously reported Br/I/Cl ratios, supporting a scenario of slab-derived fluid addition with elevated B, 11B-rich, and low Br/Cl and I/Cl, which is derived from the dehydration of subducted-sediments. The slab fluid becomes subsequently mixed with the parent magma of Milos. The deep brine reservoir is partially affected by injections of magmatic fluid/gases during degassing. The results presented here are crucial for deciphering the evolution of the brine reservoirs involved in phase separation, fluid/sediment interaction and magmatic contribution in the deep reaction zone of the Milos hydrothermal system; they also have implications in the understanding of the formation of metallic vein mineralization.

  17. Geomorphological characteristics of the onshore/offshore volcanic edifices with respect to their evolutionary stage in the South Aegean Sea, Greece.

    NASA Astrophysics Data System (ADS)

    Carey, S.; Nomikou, P.; Papanikolaou, D.; Alexandri, M.

    2014-12-01

    Volcanism in the South Aegean Sea first occurred about 3-4 million years ago, along four different volcanic island groups, including both onshore and recently discovered offshore volcanoes: 1) Starting from the west, the Methana group consists of the Methana stratovolcano, composed exclusively of volcaniclastics and lavas, creating cones and domes onland and the Paphsanias submarine cone in the Epidavros tectonic graben, bordered by E-W normal faults. It has a 2 km basal diameter at 400 m depth and its top rises to 150 m. 2) The Milos-Antimilos group consists of volcanic domes and calderas onland and three submarine domes to the east of Antimilos. A hydrothermal vent field is limited in the SE coastal zone of Milos, 3) The Santorini group consists of: (i) the older volcanic cones of Christianna islets and three submarine domes east of them, (ii) Santorini volcano which during the last 500 ka experienced repeated caldera collapses following Plinian eruptions and edifice rebuilding, represented by the growth of the Kamenes islands after the last catastrophic Late Bronze age eruption. (iii) a chain of about twenty submarine volcanic domes and craters in the Kolumbo zone northeast of Santorini. Kolumbo volcano is a 3 km diameter cone with a 1500 m wide crater, a crater rim as shallow as 18 m depth and a flat crater floor at 505 m depth containing an active hydrothermal vent field degassing 99% of CO2. 4) The Kos-Nisyros group at the eastern edge of the Hellenic Volcanic arc, comprises several domes and craters offshore and Nisyros volcano consists exclusively of alternating lava and pyroclastic deposits following several phases of reconstruction and caldera collapse. The rhyodacitic domes of Profitis Ilias are the latest evolutionary stage of Nisyros volcano which disrupted a pre-existed caldera and may be regarded as an earlier reconstruction phase similar to the Kameni islands at Santorini. The volcanic relief reaches 1100-1200 m in most cases. This is produced from

  18. Reactivation of inland normal faults triggered by extensional stress associated with the 2011 Mw 9.0 Tohoku, Japan, earthquake

    NASA Astrophysics Data System (ADS)

    Tsutsumi, H.; Toda, S.; Fukushima, Y.

    2011-12-01

    mapping correlate well with those imaged by InSAR analysis. Coseismically exposed fault planes and fault outcrops reveal that both the Yunodake and Itozawa faults dip steeply to the west. The surface trace of the Itozawa fault is in part marked by west (upslope) facing scarps suggesting repeated normal-sense of slip on the fault. The Yunodake fault also has a Neogene-Quaternary sedimentary basin on the hanging wall side of the fault. We thus interpret that the April 11 earthquake was caused by reactivation of two sub-parallel normal faults related to transient extensional stress due to the March 11 mega-thrust earthquake. If this were the case, paleoseismic trenching across the Yunodake and Itozawa faults would reveal paleoseismic history of not only these faults but also the plate interface that ruptured during the devastating event. We plan to conduct trenching studies across these faults during summer and fall, 2011.

  19. Thrust-related, diapiric, and extensional doming in a frontal orogenic wedge: example of the Montagne Noire, Southern French Hercynian Belt

    NASA Astrophysics Data System (ADS)

    Soula, Jean-Claude; Debat, Pierre; Brusset, Stéphane; Bessière, Gilbert; Christophoul, Frédéric; Déramond, Joachim

    2001-11-01

    The Montagne Noire, which is situated at the toe of the orogenic wedge of the French Massif Central South European Variscides, appears to be a well-suited area for studying the origin and evolution of middle to upper crustal domes adjacent to foreland basins. The data reported in the present paper show that the Montagne Noire dome is a particular type of basement-involved frontal culmination in an orogenic wedge and foreland basin system. This frontal culmination is characterized by a syn-contractional HT decompression recorded by clockwise PTt paths and widespread strata overturning in thrust and fold structures, which controlled the sedimentation in the adjacent foreland basin. These unusual characteristics are interpreted to be a result of the succession of thrusting, diapirism and extensional collapse. Antiformal stacking of syn-metamorphic thrust sheets controlled the first stages of the foreland basin development. Diapirism was essentially responsible for the HT decompression and widespread strata overturning. Extensional doming was a result of late- to post-metamorphic collapse acting on the pre-existing high-amplitude dome. Diapirism and associated isothermal decompression metamorphism, which constitute the essential difference between the Montagne Noire and 'ordinary' frontal ridges in orogenic wedges, were probably enhanced by a local partial melting of the upper to middle crust. It is suggested that the occurrence of these phenomena in front of an orogenic wedge was related to local over-thickening due to the superposition of an upper crustal antiformal stack on top of a lower crustal ramp anticline.

  20. Phyllosilicate injection along extensional carbonate-hosted faults and implications for co-seismic slip propagation: Case studies from the central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Smeraglia, Luca; Aldega, Luca; Billi, Andrea; Carminati, Eugenio; Doglioni, Carlo

    2016-12-01

    We document phyllosilicates occurrence along five shallow (exhumed from depths < 3 km) carbonate-hosted extensional faults from the seismically-active domain of the central Apennines, Italy. The shallow portion of this domain is characterized by a sedimentary succession consisting of ∼5-6 km thick massive carbonate deposits overlain by ∼2 km thick phyllosilicate-rich deposits (marls and siliciclastic sandstones). We show that the phyllosilicates observed within the studied carbonate-hosted faults derived from the overlying phyllosilicate-rich sedimentary deposits and were involved in the faulting processes. We infer that, during fault zone evolution, the phyllosilicates downward injected into pull-aparts (i.e., dilational jogs) that were generated along staircase extensional faults. With further displacement accumulation, the clayey material was smeared and concentrated into localized layers along the carbonate-hosted fault surfaces. These layers are usually thin (a few centimeters to decimeters thick), but can reach also a few meters in thickness. We suggest that, even in tectonic settings dominated by high frictional strength rocks (e.g., carbonates), localized layers enriched in weak phyllosilicates can occur along shallow fault surfaces thus reducing the expected fault strength during earthquakes, possibly promoting co-seismic slip propagation up to the Earth's surface.

  1. Pluton-dyke relationships in a Variscan granitic complex from AMS and gravity modelling. Inception of the extensional tectonics in the South Armorican Domain (France)

    NASA Astrophysics Data System (ADS)

    Turrillot, P.; Faure, M.; Martelet, G.; Chen, Y.; Augier, R.

    2011-11-01

    The Carnac granitic Complex (South Armorican Domain, Western France) was emplaced during Late Carboniferous times in the deepest Variscan unit, roofed by two major extensional shear zones. Through the acquisition and interpretation of field data, Anisotropy of Magnetic Susceptibility and gravity data, emphasized by petrological and structural observations, we address the emplacement model and possible magmatic processes involved between dyking to massive plutonism in a synkinematic context. Gravity modelling highlights an overall eastward thinning of the pluton, and several deep zones in the western part of the complex, interpreted as the pluton feeder zones. The internal granitic fabric, developed in a sub-solidus state, shows marked planar-linear anisotropy, consistent with a vertical shortening in the WNW-ESE regional stretching regime and eastward magma spreading. This study documents the occurrence of numerous NNE-SSW trending dykes within the eastern part of the pluton, suggesting that this granitic Complex formed by the coalescence of dykes oriented perpendicular to the regional stretching direction, and thus interpreted as large-scale “tension gashes”. The synkinematic character of the Carnac Complex intrusion, recently dated at ca. 319 ± 6 Ma, thus times the inception of the late-orogenic extensional deformation experienced in the whole South Armorican Domain.

  2. Neotectonics and geomorphic evolution of the northwestern arm of the Yellowstone Tectonic Parabola: Controls on intra-cratonic extensional regimes, southwest Montana

    USGS Publications Warehouse

    Ruleman, Chester A.; Larsen, Mort; Stickney, Michael C.

    2014-01-01

    The catastrophic Hebgen Lake earthquake of 18 August 1959 (MW 7.3) led many geoscientists to develop new methods to better understand active tectonics in extensional tectonic regimes that address seismic hazards. The Madison Range fault system and adjacent Hebgen Lake–Red Canyon fault system provide an intermountain active tectonic analog for regional analyses of extensional crustal deformation. The Madison Range fault system comprises fault zones (~100 km in length) that have multiple salients and embayments marked by preexisting structures exposed in the footwall. Quaternary tectonic activity rates differ along the length of the fault system, with less displacement to the north. Within the Hebgen Lake basin, the 1959 earthquake is the latest slip event in the Hebgen Lake–Red Canyon fault system and southern Madison Range fault system. Geomorphic and paleoseismic investigations indicate previous faulting events on both fault systems. Surficial geologic mapping and historic seismicity support a coseismic structural linkage between the Madison Range and Hebgen Lake–Red Canyon fault systems. On this trip, we will look at Quaternary surface ruptures that characterize prehistoric earthquake magnitudes. The one-day field trip begins and ends in Bozeman, and includes an overview of the active tectonics within the Madison Valley and Hebgen Lake basin, southwestern Montana. We will also review geologic evidence, which includes new geologic maps and geomorphic analyses that demonstrate preexisting structural controls on surface rupture patterns along the Madison Range and Hebgen Lake–Red Canyon fault systems.

  3. Formation and inversion of extensional ramp-syncline basins with pre-kinematic salt layers. Experimental results and application to Iberian Mesozoic analogues

    NASA Astrophysics Data System (ADS)

    Roma, Maria; Pla, Oriol; Butillé, Mireia; Roca, Eduard; Ferrer, Oriol

    2015-04-01

    The widespread extensional deformation that took place during Jurassic to Cretaceous times in the Western Europe and north-Atlantic realm resulted in the formation of several rift systems. Some of the basins associated to these rifts show broad syncline-shapes filled by thick sedimentary successions deposited overlying a hyperextended crust (i.e., Parentis, Cameros, Organyà or Columbrets basins in Iberia). The development of these syncline basins has been associated to the slip of low-angle lithospheric-scale extensional faults with ramp/flat geometries. The shape and kinematics of such faults have been usually established using the architecture of syn-kinematic layers and assuming a complete coupling of the hangingwall rocks and a layer parallel flexural slip deformation mechanism. However almost all these basins include pre-kinematic Upper Triassic salt layers which undubtoufully acted as an effective detachment decoupling the structure of sub- and suprasalt units. The presence of this salt is denoted by the growth of salt structures as diapirs or salt walls at the edges of these basins where the overburden was thinner. During latest Cretaceous and Cenozoic these basins were partially inverted and often incorporated into thrust-and-fold belts as the Pyrenees . Contractional deformation resulted in the reactivation of major extensional faults and, above the salt, the squeezing of pre-existent salt structures. The pre-kinematic salt clearly acted again as as a major detachment decoupling the contractional deformation. Using an experimental approach (scaled sand-box models) the aim of our research is threefold: 1) to determine the geometrical features of the hangingwall above a convex upwards ramp of a low angle extensional fault with and without pre-kinematic salt, and consequently; 2) to decipher the role played by a pre-kinematic viscous layer, such as salt, in the development of these syncline basins; and 3) to characterize the contractional deformation that

  4. Intimate Views of Cretaceous Plutons, the Colorado River Extensional Corridor, and Colorado River Stratigraphy in and near Topock Gorge, Southwest USA

    NASA Astrophysics Data System (ADS)

    Howard, K. A.; John, B. E.; Nielson, J. E.; Miller, J. M.; Priest, S. S.

    2010-12-01

    Geologic mapping of the Topock 7.5’ quadrangle, CA-AZ, reveals a structurally complex part of the Colorado River extensional corridor, and a younger stratigraphic record of landscape evolution during the history of the Colorado River. Paleoproterozoic gneisses and Mesoproterozoic granitoids and diabase sheets are exposed through cross-sectional thicknesses of many kilometers. Mesozoic to Tertary igneous rocks intrude the older rocks and include dismembered parts of the Late Cretaceous Chemehuevi Mountains Plutonic Suite. Plutons of this suite exposed in the Arizona part of the quad reconstruct, if Miocene deformation is restored, as cupolas capping the sill-like Chemehuevi Mountains batholith exposed in California. A nonconformity between Proterozoic and Miocene rocks reflects pre-Miocene uplift and erosional stripping of regional Paleozoic and Mesozoic strata. Thick (1-3 km) Miocene sections of volcanic rocks, sedimentary breccias, and conglomerate record the Colorado River extensional corridor’s structural and erosional evolution. Four major Miocene low-angle normal faults and a steep block-bounding Miocene fault divide the deformed rocks into major structural plates and giant tilted blocks on the east side of the Chemehuevi Mountains core complex. The low-angle faults attenuate >10 km of crustal section, superposing supracrustal and upper crustal rocks against originally deeper gneisses and granitoids. The block-bounding Gold Dome fault zone juxtaposes two large hanging-wall blocks, each tilted 90°, and splays at its tip into folds that deform layered Miocene rocks. A 15-16 Ma synfaulting intrusion occupies the triangular zone or gap where the folding strata detached from an inside corner along this fault between the tilt blocks. Post-extensional landscape evolution is recorded by upper Miocene to Quaternary strata, locally deformed. This includes several Pliocene and younger aggradational episodes in the Colorado River valley, and intervening degradation

  5. Pushing the Limits of Geological Mapping Outside the Earth: 3D Modeling of Strike-Slip and Extensional Fault Systems in Meridiani Planum Region, Mars.

    NASA Astrophysics Data System (ADS)

    Vidal Royo, O.

    2014-12-01

    GIS and geological modeling software have radically changed the means by which geological mapping is produced, published and visualized. This type of software environment normally requires a spatially aware reference system to position data and interpretation, often referred as georeferenced data (i.e. geographic data referenced on the Earth). However, for this study we coin the term areoreferenced data (i.e. Mars-referenced "geographic" data). Thanks to the wealth of areoreferenced data made available by the NASA and the HiRise at University of Arizona it is now possible to carry out 3D areographic and areologic (i.e. related to the topography and geology of Mars, respectively) reconstructions in great detail. The present work benefits from the availability of software and areographic data, and presents the results of an areologic map and 3D model of the fault systems in the Meridiani Planum of Mars. The work has been carried out in Move™ (developed by Midland Valley Exploration), a geological modeling toolkit that allows for easy data loading in a wide range of formats as well as straightforward 2D/3D model building tools of geological bodies. Initial data consisted of Digital Terrain Model and orthoimages (NASA/JPL/University of Arizona/USGS). From these we have interpreted several structural domains: right-lateral strike-slip systems with associated releasing bends, which gave room to an extensional event causing a horizontal-axis rotation of the bedding. Bedding ranges from subhorizontal in the southern domain where strike-slip prevails to nearly 40º in the central and northern domains, where a more complex interaction between strike-slip and extensional faults is described. The stratigraphic sequence is mainly composed by moderately rounded well laminated basaltic sandstones (Squyres et al., 2004) in which a high component of sulfurs (e.g. sulfate anhydrate, hexahydrite, epsomite, gypsum) and salts (e.g. halite) has been described (Squyres et al., 2004

  6. Tectono-sedimentary evolution of an extensional basin revealed by a combined photo-geological and field-mapping approach. The Montefalco Basin (Northern Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Bucci, Francesco; Mirabella, Francesco; Santangelo, Michele; Cardinali, Mauro; Guzzetti, Fausto

    2016-04-01

    Active extensional basins are important since their sedimentary infills and bounding tectonic structures provide: i) sinks with preservation potential for sedimentary and fossil records of past changes in climate and sediment/water supply, ii) information on the growth, activity, decay and death of normal faults, iii) vast economic reserves of hydrocarbons, water and minerals. Unfortunately, quaternary extensional basins, especially if located in humid and temperate climate environments, are often characterized by extensively cultivated areas, homogeneous terrains and quite flat morphologies. Furthermore, they commonly host human settlements, together with roads, economic and industrial infrastructures, with a consequent limited availability of good outcrops. Such a limitation can (often severely) hamper an adequate mapping of the sedimentary infill. Therefore alternative methodological approaches (such as aerial photographs interpretation, API) are needed to integrate heterogeneous and incomplete datasets. This contribution presents an updated photo-geological map of a Quaternary extensional basin in Central Italy, the Montefalco Basin. This basin developed in a continental environment characterized by clayey-sandy lacustrine and fluvial sequences (late Pliocene - early Pleistocene) underlying more recent coarse grained deposits related to alluvial fan environment (early-to-late Pleistocene) and younger palustrine deposits (late Pleistocene). Since the late Pleistocene, regional uplift and local tectonics led to the end of deposition in the Montefalco basin, which experienced a diffuse incision and the modification of the drainage network, in response to the W-to-E migration of active faulting and tectonic subsidence. The new photo-geological map represents an important improvement compared to the existing data, since it provides unprecedented and spatially distributed information on the geometry of the continental deposits and on the tectonic structures affecting

  7. A Lower Carboniferous two-stage extensional basin along the Avalon-Meguma terrane boundary: Evidence from southeastern Isle Madame, Nova Scotia

    USGS Publications Warehouse

    Force, E.R.; Barr, S.M.

    2006-01-01

    Anomalously thick and coarse clastic sedimentary successions, including over 5000 m of conglomerate, are exposed on Isle Madame off the southern coast of Cape Breton Island. Two steeply to moderately dipping stratigraphic packages are recognized: one involving Horton and lower Windsor groups (Tournasian-Visean); the other involving upper Windsor and Mabou (Visean-Namurian) groups. Also anomalous on Isle Madame are three long narrow belts of "basement" rocks, together with voluminous chloritic microbreccia and minor semi-ductile mylonite, which are separated from the conglomerate-dominated successions by faults. The angular relations between the cataclastic rocks and the conglomerate units, combined with the presence of cataclasite clasts in the conglomerate units and evidence of dip-slip faults within the basin, suggest an extensional setting, where listric normal faults outline detachment allochthons. Allochthon geometry requires two stages of extension, the older stage completed in early Windsor Group time and including most of the island, and the more local younger stage completed in Mabou Group time. Domino-style upper-plate faulting in the younger stage locally repeated the older detachment relation of basement and conglomerate to form the observed narrow belts. Re-rotation of older successions in the younger stage also locally overturned the Horton Group. These features developed within a broad zone of Carboniferous dextral transcurrent faulting between already-docked Avalon and Meguma terranes. Sites of transpression and transtension alternated along the Cobequid-Chedabucto fault zone that separated these terranes. The earlier extensional features in Isle Madame likely represent the northern headwall and associated clastic debris of a pull-apart or other type of transtensional basin developed along part of this fault zone that had become listric; they were repeated and exposed by being up-ended in the second stage of extension, also on listric faults. The

  8. Hf isotope study of Palaeozoic metaigneous rocks of La pampa province and implications for the occurrence of juvenile early Neoproterozoic (Tonian) magmatism in south-central Argentina

    NASA Astrophysics Data System (ADS)

    Chernicoff, C. J.; Zappettini, E. O.; Santos, J. O. S.; Belousova, E.; McNaughton, N. J.

    2011-12-01

    On a global scale, juvenile Tonian (Early Neoproterozoic) magmatic rocks are associated with the extensional events that lead to the breakup of the Rodinia supercontinent. In Argentina, no geological record is available for this time interval, lasting from 1000 to 850 Ma. We present indirect evidence for the existence of Tonian extension in Argentina, as supported by Hf and Nd isotope determinations on Phanerozoic magmatic and sedimentary rocks. We mainly focus on our own Hf isotope determinations carried out on U-Pb SHRIMP dated zircons from Palaeozoic metaigneous rocks of La Pampa province, south-central Argentina, i.e. metagabbros of Valle Daza, dioritic orthogneiss of Estancia Lote 8, and metadiorite of Estancia El Carancho, having found that these rocks were derived from sources of ca. 920 to ca 880 Ma, with ɛHf values between +6.83 and + 9.59. Inherited zircons of this age and character identified in these rocks also point to the same source. We also compile additional Hf and Nd studies from previous work on Phanerozoic magmatic and sedimentary rocks. We preliminarily compare the age of the juvenile Tonian sources referred to in our work with that of two extensional events identified in the São Francisco craton, Brazil.

  9. Seismic slip at the base of the seismogenic crust along the exhumed extensional Oligocene Trois Villes Fault (Western Italian Alps)

    NASA Astrophysics Data System (ADS)

    Bistacchi, A.; Pennacchioni, G.; Gatta, G. D.; Grizzetti, R.

    2009-04-01

    The Trois Villes Fault is a major Oligocene extensional fault of the internal NW Alps that offsets of ca. 1 km the flat-lying boundary between the Austroalpine basement (hangingwall) and Piedmont calcschists (footwall). Faulting developed at conditions close to the base of the seismogenetic crust during a regional phase of post-collisional orogen-perpendicular extension (Bistacchi and Massironi, 2000). Fault rocks derived from banded greenschist facies felsic mylonites (predating this faulting event), consisting of an alternation of decimetre-thick leucocratic quartz-feldspar-rich layers and green phyllosilicate-rich mylonites (white mica and chlorite). They include: (i) green protocataclasites to ultracataclasites, which form two main metric layers within the 8-15 m-thick fault zone, and (ii) pseudotachylytes, forming a single decimetric zoned fault vein, continuous over distances of tens of meters, within each one of the two cataclasite layers . Cataclasites are characterized by stable quartz+albite+chlorite+epidote+titanite, hence developed under low-temperature greenschist facies conditions (about 270-300°C, 8-10 km). Pseudotachylytes are localized within the ultracataclasite domains and consist of several contiguous subparallel fault veins. Injection veins are rare and small. Different veins show different clast/matrix ratios, ranging from clast-dominated to almost clast-free end-members. The clast-rich pseudotachylytes contain lithic clasts of host mylonites, cataclasites and early pseudotachylytes, and monocrystalline clasts of quartz, albite and apatite. Chlorite and white mica do not occur as monomineralic clasts. Pseudotachylytes lack features sometimes considered diagnostic of frictional melts (glass, spherulites, etc.), but show a rather homogeneous matrix, which almost entirely consists of a K-feldspar (92% Or) classified (by means of crystallographic analysis) as low sanidine. This distinctive matrix mineralogy indicates crystallization at ca. 1000

  10. Inferences of Integrated Lithospheric Strength from Plate-Scale Analyses of Deformation Observed in the Aegean-Anatolian Region and the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Houseman, Gregory

    2016-04-01

    In the context of a comprehensive review of the rheology and strength of the lithosphere (Marine and Petroleum Geology, 2011, doi:10.1016/j.marpetgeo.2011.05.008), Evgene Burov described the difficulty of extrapolating rock deformation laws derived from laboratory experiments to the time and length scales that apply when the Earth's lithosphere is deformed. Not only does the extrapolation introduce a large uncertainty, but even the relative importance of different possible mechanisms of deformation may be uncertain. Even though lithospheric deformation has a strong conceptual and theoretical basis, it is therefore essential, as Burov argued, that deformation laws for the lithosphere must be calibrated by using observations of deformation that occurs on a lithospheric length scale and at geological strain rates. The influence of regionally varying factors like crustal thickness, geothermal gradient and tectonic environment may induce large variations in how rapidly the lithosphere may deform in response to an applied load, not least in the contrast from continent to ocean. Plates may be deformed by different loading mechanisms but, when deformation is distributed over a broad region, the strain-rate field may be approximately constant with depth and we may integrate the in-plane stress components across the thickness of the lithosphere to derive a depth-averaged constitutive law for the deformation. This approximation is the basis for the thin viscous sheet formulation of lithospheric deformation and, in combination with appropriate observations, it allows us to calibrate the integrated resistance to processes like regional extension or convergence. In this talk I will summarise what we learn about effective lithospheric rheology from two recent studies of the distribution and rates of diffuse deformation of the lithosphere in, firstly the Anatolian-Aegean region, and secondly the Central Indian Ocean. In the first case the distribution of deformation is consistent

  11. Depositional architecture of a mixed travertine-terrigenous system in a fault-controlled continental extensional basin (Messinian, Southern Tuscany, Central Italy)

    NASA Astrophysics Data System (ADS)

    Croci, Andrea; Della Porta, Giovanna; Capezzuoli, Enrico

    2016-03-01

    The extensional Neogene Albegna Basin (Southern Tuscany, Italy) includes several thermogene travertine units dating from the Miocene to Holocene time. During the late Miocene (Messinian), a continental fault-controlled basin (of nearly 500-km2 width) was filled by precipitated travertine and detrital terrigenous strata, characterized by a wedge-shaped geometry that thinned northward, with a maximum thickness of nearly 70 m. This mixed travertine-terrigenous succession was investigated in terms of lithofacies types, depositional environment and architecture and the variety of precipitated travertine fabrics. Deposited as beds with thickness ranging from centimetres to a few decimetres, carbonates include nine travertine facies types: F1) clotted peloidal micrite and microsparite boundstone, F2) raft rudstone/floatstone, F3) sub-rounded radial coated grain grainstone, F4) coated gas bubble boundstone, F5) crystalline dendrite cementstone, F6) laminated boundstone, F7) coated reed boundstone and rudstone, F8) peloidal skeletal grainstone and F9) calci-mudstone and microsparstone. Beds of terrigenous deposits with thickness varying from a decimetre to > 10 m include five lithofacies: F10) breccia, F11) conglomerate, F12) massive sandstone, F13) laminated sandstone and F14) claystone. The succession recorded the following three phases of evolution of the depositional setting: 1) At the base, a northward-thinning thermogene travertine terraced slope (Phase I, travertine slope lithofacies association, F1-F6) developed close to the extensional fault system, placed southward with respect to the travertine deposition. 2) In Phase II, the accumulation of travertines was interrupted by the deposition of colluvial fan deposits with a thickness of several metres (colluvial fan lithofacies association, F10 and F12), which consisted of massive breccias, adjacent to the alluvial plain lithofacies association (F11-F14) including massive claystone and sandstone and channelized

  12. Reactivation of compressional pre-existing structures in an extensional regime by wastewater re-injection induced seismicity: a Southern Appennine (Italy) oilfield case study

    NASA Astrophysics Data System (ADS)

    Buttinelli, M.; Improta, L.; Bagh, S.; Chiarabba, C.

    2015-12-01

    The Val d'Agri Quaternary basin is located within the Southern Apennine extensional belt, hosting the largest oilfield in Europe. Since 2006 wastewaters coming from oil production were re-injected by a single disposal well into the reservoir, represented by the carbonates of the Apulian platform. Consequently, induced micro-seismicity (219 events, ML < 2.3) was recorded close to the beginning of injection and within 5 km of the well. Afterwards, a detailed analysis of the oilfield underground dataset was performed to define a 3D geological model of the injection site. A pre-existing thrust system inherited by a Plio-Pleistocene compressional tectonic phase mainly constituted by NE-verging high-angle thrusts and SW-verging back-thrusts interesting the Apulian carbonates was interpreted. Below the injection well a mainly E-dipping back-thrust completely developed between two major thrusts can be modeled. The depth conversions of seismic interpretation based on sonic logs, VSP and seismic check-shots highlighted that the back-thrust geometry is compatible with accurate 3D absolute location and high precision relative location of induced events. Such analysis also show that wastewater injection firstly caused the reactivation of the deep portion of the back-thrust, and then seismicity mainly migrated up-dip toward shallower depths and interesting some portions of other faults, but remaining almost confined within the reservoir volume, and close to the injection well. These combined results also suggest that induced events presumably occurred on a small and high-permeability patch of the fault zone, favorably oriented with respect to the present-day SW-NE trending extensional stress field. Results can be read in the light of understanding the impact that induced seismicity due to the reactivation of pre-existing/inactive faults might have on seismic hazard and seismogenic potential evaluations, especially in tectonically active areas like Italy

  13. Structure and U-Pb zircon geochronology of an Alpine nappe stack telescoped by extensional detachment faulting (Kulidzhik area, Eastern Rhodopes, Bulgaria)

    NASA Astrophysics Data System (ADS)

    Georgiev, Neven; Froitzheim, Nikolaus; Cherneva, Zlatka; Frei, Dirk; Grozdev, Valentin; Jahn-Awe, Silke; Nagel, Thorsten J.

    2016-10-01

    The Rhodope Metamorphic Complex is a stack of allochthons assembled during obduction, subduction, and collision processes from Jurassic to Paleogene and overprinted by extensional detachment faults since Middle Eocene. In the study area, the following nappes occur in superposition (from base to top): an orthogneiss-dominated unit (Unit I), garnet-bearing schist with amphibolite and serpentinite lenses (Unit II), greenschist, phyllite, and calcschist with reported Jurassic microfossils (Unit III), and muscovite-rich orthogneiss (Unit IV). U-Pb dating of zircons from a K-feldspar augengneiss (Unit I) yielded a protolith age of ca. 300 Ma. Garnet-bearing metasediment from Unit II yielded an age spectrum with distinct populations between 310 and 250 Ma (detrital), ca. 150 Ma, and ca. 69 Ma (the last two of high-grade metamorphic origin). An orthogneiss from Unit IV yielded a wide spectrum of ages. The youngest population gives a concordia age of 581 ± 5 Ma, interpreted as the age of the granitic protolith. Unit I represents the Lower Allochthon (Byala Reka-Kechros Dome), Unit II the Upper Allochthon (Krumovitsa-Kimi Unit), Unit III the Uppermost Allochthon (Circum-Rhodope Belt), and Unit IV a still higher, far-travelled unit of unknown provenance. Telescoping of the entire Rhodope nappe stack to a thickness of only a few 100 m is due to Late Eocene north directed extensional shearing along the newly defined Kulidzhik Detachment which is part of a major detachment system along the northern border of the Rhodopes. Older top-to-the south mylonites in Unit I indicate that Tertiary extension evolved from asymmetric (top-to-the-south) to symmetric (top-to-the-south and top-to-the-north), bivergent unroofing.