the crustal deformation revealed by gps and insar in the northwest corner of the tarim basin northwestern china the northwestern corner of the tarim basin hereinafter the noctb is surrounded by the pamir salient the south tian shan mountains and the tarim basin the tectonic settings of these three structures dominate the crustal deformation patterns and seismic events in the noctb and its adjacent regions we integrated the gps and insar measurements to derive a large scale three dimensional velocity map of the noctb the gps data obtained during 38 campaigns between 1992 and 2013 were used to derive a horizontal velocity field 149 envisat asar images observed along four satellite tracks between 2003 and 2011 were processed to get a line of sight rate map based on the small baseline subset time series analysis method and a homogeneous isotropic model finally we modeled the dip angle slip rate and locking depth of selected faults the results indicate that the crustal convergence is not uniformly distributed across the noctb more than 50 of the n s shortening is absorbed by the tian shan mountains in the southwest whereas the n s shortening rates are low and therefore the strain accommodations are smaller in the east of the noctb the vertical displacement rates in the noctb range from 2 to 3 mm year with different magnitudes in different areas the main uplift areas are located on the junction region between frontal mpt and the southwestern stt including the kazkeaerte fault aikenerte fault the southern artux fault and part areas in north of the kalping fault the main subsident areas are located on central belt of stt including the totgumbaz alpaleh fault nothern artux fault the southwestern karatieke fault and the north of puchang piqiang fault compared with the substantial n s shortening rate of 10 mm year the vertical rate across each fault ranges from approximately 1 to 1 mm year suggesting that vertical movement in noctb area is relatively moderate at present both the horizontal and vertical rates show obvious changes across the kazkeaerte fault and the kuzgong fault revealing that the basin mountain junction region between the pamir the tarim basin and the south tian shan mountains is subject to accumulate strain and triggers stronger earthquakes the kuzgong fault plays an important role of transforming the crustal movements between the southwestern end of the stt and the north frontal mpt the displacement field from geodetic observations could not find any evidence that the puchang piqiang fault is a geological boundary of kepingtage nappe the modeled fault geometry and slip rate imply that three faults in the noctb are slipping at 6 10 mm year along a decollement fault that dips at 19 27 and is locked at a shallow depth of 6 10 km whereas some other faults are undergoing a status of interseismic slip deficit

block models of crustal motion in southern california constrained by gps measurements 1 we estimate slip rates on major active faults in southern california using a block model constrained by global positioning system measurements of interseismic deformation the block model includes the effects of block rotation and elastic strain accumulation consistent with a simple model of the earthquake cycle our estimates of the right lateral strike slip rate on the san andreas fault vary by at least a factor of 5 from a high of 35 9 0 5 mm yr in the carrizo plain to a low of 5 1 1 5 mm yr through the san bernadino segment shortening across the puente hills thrust and left lateral slip on the raymond hill fault are consistent with both thickening and escape tectonics in the los angeles basin discrepancies between geodetic and geologic slip rate estimates along the san andreas and san jacinto faults as well as in the eastern california shear zone may be explained by a temporal change in fault system behavior we find no substantial evidence for long term postseismic relaxation and infer that the viscosity of the lower crust upper mantle may be relatively high 1019 pa s

lateral extrusion of lower crust from under high topography in the isostatic limit where there is isostasy the rocks of the lower continental crust are subject to an effective lateral pressure gradient equal to the gradient of topographic load whether compensation is in crustal roots or in the mantle the result is a poiseuille flow planar channel flow in the weak lower crust which removes crust from under mountains and smooths and levels the topography assuming cubic power law creep the flux of crust is proportional to the third power of the topographic gradient to the usual arrhenius term to the tenth power of the absolute temperature of the lower crust and to the negative fifth power of the geothermal gradient the result is that any initial condition with an isolated high tends eventually toward a state where the topography is pancake shaped with a flat central plateau and steeper flanks spreading outward when adjacent pancakes merge most of the relief is eliminated flow may either roughen or smooth the moho depending on whether there are lateral density contrasts in the mantle lithosphere or not although it is difficult to find analytic solutions for this evolution it is easily simulated numerically using various published flow laws for plausible lower crustal rocks lateral extrusion is shown to be insignificant under the oceans marginally significant under shields and platforms important under elevated plains and dominant beneath high plateaus and or hot delaminated regions in particular the basin and range province of the western united states cannot maintain short wavelength 100 km moho relief of more than 1 km for times greater than 10 20 m y at most if the tibetan plateau of china has been delaminated as recently suggested then it may flatten even faster reducing 100 km wavelength topographic features to 200 m relief in no more than 0 03 0 13 m y and leaving only features with wavelengths over 400 km at the present therefore the lower crust of tibet may resemble a hydraulic reservoir as previously suggested because the flatness of the moho is self maintained in these regions information on past tectonics is continually lost and the present moho shape cannot be used to balance cross sections for times in the past the flatness of the moho today is not a constraint on the mechanisms of extension or shortening in these regions nor is it evidence for underplating by intrusions it also follows that very intense and inhomogeneous dilational strains may have occurred locally as in the metamorphic core complexes of the basin and range province

sequence stratigraphy tectonics and depositional history in eastern thrace basin nw turkey abstract the eastern thrace basin forms the eastern portion of the turkish thrace basin in nw turkey the pre tertiary crystalline basement shows platform and deep basin depositional morphology which results in facies pattern and thickness distribution localization during the early stages of basin development in middle to late eocene time normal fault controlled early and lateral reverse fault controlled later stage tectonic events characterize basin geometry and the present topography respectively the early stage normal faulting caused subsidence and sediment accumulation in the late eocene and early oligocene while later stage tectonic events caused intense deformation and structuration in the early to middle miocene as a result southeastern and northern regions were folded or uplifted and deeply eroded outcrop well log core and reflection seismic studies reveal that the sedimentary succession can be subdivided into five characteristic depositional sequences bounded at their base by unconformities these unconformities were dated using paleontological data the sequence boundaries underlying consecutively sequences 1 2 3 and 5 were dated at 39 5 36 30 and 25 5 ma from older to young in order of succession corresponding to the major erosional breaks between the middle and upper eocene the upper eocene and the lower oligocene the lower and upper oligocene and the upper oligocene and the lower miocene the sequence boundary underlying sequence 4 was determined to lie within the late oligocene succession and as an age designation could not be assigned it was termed intra sequence boundary isb the first two sequences correspond to relative sea level rises and a normal fault controlled tectonism coincides with them reefal carbonates coarse grained clastics and marine shales with abundant volcanic flows or layers represent the sedimentary facies of these two early sequences the third and fourth sequences correspond to either a decreased relative rise of sea level or a relative still stand of sea level and a sediment induced subsidence related to thermal relaxation provides accommodation prograding delta sediments of varying extent constitute the sedimentary packages of these two sequences the depositional sequence 5 which makes up the uppermost part of the sedimentary succession in the basin corresponds to a relative sea level fall and a tectonic style shaped by lateral and inversion faulting characterizes this period nonmarine alluvial fan fluvial channel and various lagoonal deposits constitute the sedimentary facies of this last sequence porous reefal limestones and shallow marine beach sandstones of sequence 1 and deltaic sandstones of sequences 3 and 4 provide good reservoir rocks for the hydrocarbons produced in the study area the marine shales and marls of the second and the third sequences provide good source rocks as they are rich in disseminated organic matter content although the non marine alluvial and fluvial channel deposits of sequence 5 are good reservoirs they lack effective seals the time interval in which sequence 5 was deposited represents a period of major structural and trap development in the basin

vector constraints on western u s deformation from space geodesy neotectonics and plate motions the rate of slip vector on the san andreas fault in central california estimated from geodetic and holocene geological data 34 3 mm yr n41 w 2 is inconsistent with the prediction of rigid plate models such as rm2 56 3 mm yr n35 w 2 this well known san andreas discrepancy is diagnostic of plate deformation distributed both east of the fault in the basin and range and west of the fault along the california continental margin we construct constraints on the integrated deformation rates across these two regions consistent with 1 the kinematical boundary conditions imposed by the rigid plate model 2 neotectonic and paleoseismic estimates of deformation rates 3 ground based geodetic measurements and 4 rates of change observed by very long baseline interferometry along seven baselines to western u s sites the space geodetic data on basin and range extension taken over a 4 year interval are compatible with geological observations averaged over the holocene the best estimate of its integrated deformation rate provided by the joint inversion of both data types is 9 7 2 1 mm yr n56 w 10 too small and in the wrong direction to account entirely for the san andreas discrepancy we therefore attribute much of it to deformation west of the sierra nevada great valley block accommodated for example on faults such as the san gregorio hosgri system of coastal california the integral of this deformation estimated by subtracting the basin and range contribution from the discrepancy vector requires significant right lateral shear parallel to the san andreas 13 5 mm yr and some compression perpendicular to it 9 3 mm yr

along strike variations of the partitioning of convergence across the haiyuan fault system detected by insar oblique convergence across tibet leads to slip partitioning with the coexistence of strike slip normal and thrust motion on major fault systems a key point is to understand and model how faults interact and accumulate strain at depth here we extract ground deformation across the haiyuan fault restraining bend at the northeastern boundary of the tibetan plateau from envisat radar data spanning the 2001 textendash2011 period we show that the complexity of the surface displacement field can be explained by the partitioning of a uniform deep seated convergence mountains and sand dunes in the study area make the radar data processing challenging and require the latest developments in processing procedures for synthetic aperture radar interferometry the processing strategy is based on a small baseline approach before unwrapping we correct for atmospheric phase delays from global atmospheric models and digital elevation model errors a series of filtering steps is applied to improve the signal to noise ratio across high ranges of the tibetan plateau and the phase unwrapping capability across the fault required for reliable estimate of fault movement we then jointly invert our insar time series together with published gps displacements to test a proposed long term slip partitioning model between the haiyuan and gulang left lateral faults and the qilian shan thrusts we explore the geometry of the fault system at depth and associated slip rates using a bayesian approach and test the consistency of present day geodetic surface displacements with a long term tectonic model we determine a uniform convergence rate of 10 8 6 textendash11 5 mm yr 1 with an n89 81 textendash97 e across the whole fault system with a variable partitioning west and east of a major extensional fault jog the tianzhu pull apart basin our 2 d model of two profiles perpendicular to the fault system gives a quantitative understanding of how crustal deformation is accommodated by the various branches of this thrust strike slip fault system and demonstrates how the geometry of the haiyuan fault system controls the partitioning of the deep secular motion

surface deformation and lower crustal flow in eastern tibet field observations and satellite geodesy indicate that little crustal shortening has occurred along the central to southern margin of the eastern tibetan plateau since about 4 million years ago instead central eastern tibet has been nearly stationary relative to southeastern china southeastern tibet has rotated clockwise without major crustal shortening and the crust along portions of the eastern plateau margin has been extended modeling suggests that these phenomena are the result of continental convergence where the lower crust is so weak that upper crustal deformation is decoupled from the motion of the underlying mantle this model also predicts east west extension on the high plateau without convective removal of tibetan lithosphere and without eastward movement of the crust east of the plateau

earthquakes drive focused denudation along a tectonically active mountain front abstract earthquakes cause widespread landslides that can increase erosional fluxes observed over years to decades however the impact of earthquakes on denudation over the longer timescales relevant to orogenic evolution remains elusive here we assess erosion associated with earthquake triggered landslides in the longmen shan range at the eastern margin of the tibetan plateau we use the m w 7 9 2008 wenchuan and m w 6 6 2013 lushan earthquakes to evaluate how seismicity contributes to the erosional budget from short timescales annual to decadal as recorded by sediment fluxes to long timescales kyr to myr from cosmogenic nuclides and low temperature thermochronology over this wide range of timescales the highest rates of denudation in the longmen shan coincide spatially with the region of most intense landsliding during the wenchuan earthquake across sixteen gauged river catchments sediment flux derived denudation rates following the wenchuan earthquake are closely correlated with seismic ground motion and the associated volume of wenchuan triggered landslides r 2 0 6 and to a lesser extent with the frequency of high intensity runoff events r 2 0 36 to assess whether earthquake induced landsliding can contribute importantly to denudation over longer timescales we model the total volume of landslides triggered by earthquakes of various magnitudes over multiple earthquake cycles we combine models that predict the volumes of landslides triggered by earthquakes calibrated against the wenchuan and lushan events with an earthquake magnitude frequency distribution the long term landslide sustained seismic erosion rate is similar in magnitude to regional long term denudation rates 0 5 1 mm yr 1 the similar magnitude and spatial coincidence suggest that earthquake triggered landslides are a primary mechanism of long term denudation in the frontal longmen shan we propose that the location and intensity of seismogenic faulting can contribute to focused denudation along a high relief plateau margin

crustal structure across longmenshan fault belt from passive source seismic profiling 1 we analyse receiver functions from 29 broad band seismographs along a 380 km profile across the longmenshan lms fault belt to determine crustal structure beneath the east tibetan margin and sichuan basin the moho deepens from about 50 km under songpan ganzi in east tibet to about 60 km beneath the lms and then shallows to about 35 km under the western sichuan basin the average crustal vp vs ratios vary in the range 1 75 1 88 under songpan ganzi in east tibet 1 8 2 0 under the lms and decrease systematically across the nw part of the sichuan basin to less than 1 70 a negative phase arrival above the moho under songpan ganzi and sichuan basin is interpreted as a ps conversion from the top of a low velocity layer in the lower crust the very high crustal vp vs ratio and negative polarity ps conversion at the top of lower crust in east tibet are inferred to be seismic signatures of a low viscosity channel in the eastern margin of the tibetan plateau the lateral variation of moho topography crustal vp vs ratio and negative polarity ps conversion at the top of the lower crust along the profile seem consistent with a model of lower crust flow or tectonic escape

the influence of a weak upper ductile detachment on the longmen shan fold and thrust belt eastern margin of the tibetan plateau insights from sandbox experiments abstract the topic of the longmen shan fold and thrust belt has been vigorously debated due to the steep topography in contrast with the low convergence rate and earthquake hazards the longmen shan fold and thrust belt is characterized by two main detachments a strong lower detachment at 15 17 km depth in the hinterland and a weak upper detachment at 7 km depth in the sichuan basin nevertheless how the two detachments control deformation in the longmen shan remains unclear in this study we focus on the mechanical strengths of the two detachments in the study area and design three analog models to investigate the kinematics and mechanisms of the longmen shan fold and thrust belt all three model experiments have the same strong lower detachments at the basement but different upper detachments the results indicate that for model 1 with no upper detachment and model 2 with a strong frictional upper detachment the strain and deformation only concentrate near the mobile backwall and particle image velocimetry analysis reveals that both models deform in the forward in sequence style however for model 3 with a weak ductile upper detachment the strain and deformation propagate into the foreland and the model deforms in the out of sequence style consistent with the longmen shan fold and thrust belt the model results indicate that the spatial relation of strong lower detachment and weak upper detachment may be one of the important factors producing the current structural pattern and the out of sequence style of the longmen shan fold and thrust belt

the thrace basin and the black sea the eocene oligocene marine connection the late cretaceous recent west black sea basin and the eocene oligocene thrace basin are separated by the strandja arch comprising metamorphic and magmatic rocks since late cretaceous time the strandja arch formed a palaeo high separating the two basins which accumulated clastic sediment of 9 km thickness during late eocene early oligocene time the marine connection between these basins existed through the catalca gap west of istanbul the catalca gap lies on the damage zone of a major cretaceous strike slip fault it formed a 15 km wide marine gateway where carbonate rich sediments of thickness c 350 m were deposited the sequence consists of upper eocene shallow marine limestones sbz18 20 overlain by upper eocene lower oligocene p16 p19 zones pelagic marl with a rich fauna of planktonic foraminifera the marls are intercalated with 31 32 ma acidic tuff and calc arenite beds the catalca gap is bounded in the west by a major normal fault which marks the eastern boundary of the thrace basin seismic reflection profiles well data and zircon u pb ages indicate that the thrace basin sequence west of the fault is late eocene middle oligocene 37 27 ma in age and that the fault has accommodated 2 km of subsidence although there was a marine connection between the west black sea and thrace basins during late eocene early oligocene time no significant exchange of clastic sediment took place sedimentation in the catalca gap ended abruptly during early oligocene time by uplift and this eventually led to the paralic conditions in the thrace basin

kinematic fault slip evolution source models of the 2008 m7 9 wenchuan earthquake in china from sar interferometry gps and teleseismic analysis and implications for longmen shan tectonics the m w 7 9 2008 wenchuan earthquake ruptured about 280 km of faults in the longmen shan of sichuan province china at the eastern edge of the tibetan plateau we use teleseismic waveforms with geodetic data from global positioning system synthetic aperture radar interferometry and image amplitude correlation to produce a source model of this earthquake the model describes evolution of fault slip during the earthquake the geodetic data constrains the spatial distribution of fault slip and the seismic waveforms constrain mostly the time evolution of slip we find that the earthquake started with largely thrust motion on an imbricate system of faults beneath the central longmen shan including the beichuan fault and pengguan fault with fault slip at depth extending up to 50 km northwest of the mountain front the fault ruptures continued northeast along the beichuan fault with more oblique slip right lateral and thrust and the proportion of lateral motion increasing in the northern longmen shan the northernmost fault segment has a much steeper dip consistent with nearly pure strike slip motion the kinematic source model shows that the rupture propagated to the northeast at about 2 5 3 0 km s 1 producing a cascade of subevents with a total duration of about 110 s the complex fault ruptures caused shortening and uplift of the extremely steep central longmen shan which supports models where the steep edge of the plateau is formed by thrusting over the strong crust of the sichuan basin

contemporary crustal deformation of northeast tibet from geodetic investigations and a comparison between the seismic and geodetic moment release rates abstract we processed the data recorded by 32 continuous gps stations from the crustal movement observation network of china and combined them with published gps observations in a common geodetic reference frame to better depict the ongoing crustal velocities and deformation field of northeast tibet the derived velocity field indicates that the deformation of northeast tibet is characterized mainly by crustal shortening coupled with the eastward extrusion of crustal material and clockwise block rotation we further used the gps velocity field to evaluate the strain rate tensors by the method of sandwell and wessel 2016 the strain rate field shows an obvious transition of the contraction rate from ne sw to nee sww and a decrease in the maximum shear strain rate from west to east was observed along the east kunlun fault and haiyuan fault indicating that the block rotation and lateral extrusion therein may be partitioned by ne sw oriented compression to some extent the inhomogeneity of the rotation strain rate implies that northeast tibet does not behave like a single rigid block but instead resembles a left lateral shear zone supporting the hypothesis that the northward transfer of motion along the east kunlun fault may play a significant role in the deformation style of this area the dilatation rate verified that most of northeast tibet experiences crustal thickening which coincides with the average uplift rate of 1 mm y revealed by gps velocities and channel steepness indices we also estimated the geodetic moment rates and compared them with the seismic moment rates estimated using the truncated gutenberg richter earthquake distribution the ratio of the seismic strain rate to the geodetic strain rate in the regions near the altyn tagh fault the qaidam basin adjoining the qilian mountains the haiyuan fault and the central part of the east kunlun fault are near unity indicating that the deformation in these areas is dominated by seismic release and may represent fully coupled seismogenic zones the occurrence of large earthquakes in the past estimated magnitudes m 6 coupled with a high geodetic deformation rate in these regions could indicate overdue m 6 earthquakes however other factors including the occurrence of creep and the long recurrence time of mw 8 0 earthquakes should be taken into consideration along the haiyuan fault by contrast in other regions including the southern and eastern parts of the haiyuan fault along the elashan fault and the northern qilian mountains the geodetic moment rate is higher than the seismic moment rate by a factor between 3 and 9 we propose that this phenomenon is related to the undersampling of long term earthquake rates within the seismic catalogue long term aseismic crustal deformation or a combination of these factors our study has implications for better comprehending the current seismotectonic pattern of northeast tibet

fault geometry and slip distribution of the 2008 mw 7 9 wenchuan china earthquake inferred from gps and insar measurements author s wan y shen zk burgmann r sun j wang m abstract the authors 2016 published by oxford university press on behalf of the royal astronomical society we revisit the problem of coseismic rupture of the 2008 mw 7 9 wenchuan earthquake precise determination of the fault structure and slip distribution provides critical information about the mechanical behaviour of the fault system and earthquake rupture we use all the geodetic data available craft a more realistic earth structure and fault model compared to previous studies and employ a nonlinear inversion scheme to optimally solve for the fault geometry and slip distribution compared to a homogeneous elastic half space model and laterally uniform layered models adopting separate layered elastic structure models on both sides of the beichuan fault significantly improved data fitting our results reveal that 1 the beichuan fault is listric in shape with near surface fault dip angles increasing from 36 at the southwest end to 83 at the northeast end of the rupture 2 the fault rupture style changes from predominantly thrust at the southwest end to dextral at the northeast end of the fault rupture 3 fault slip peaks near the surface for most parts of the fault with 8 4mthrust and 5 m dextral slip near hongkou and 6 m thrust and 8 4 m dextral slip near beichuan respectively 4 the peak slips are located around fault geometric complexities suggesting that earthquake style and rupture propagation were determined by fault zone geometric barriers such barriers exist primarily along restraining left stepping discontinuities of the dextralcompressional fault system 5 the seismic moment released on the fault above 20 km depth is 8 2 1021 n m corresponding to an mw 7 9 event the seismic moments released on the local slip concentrations are equivalent to events of mw 7 5 at yingxiu hongkou mw 7 3 at beichuan pingtong mw 7 2 near qingping mw 7 1 near qingchuan and mw 6 7 near nanba respectively 6 the fault geometry and kinematics are consistent with a model in which crustal deformation at the eastern margin of the tibetan plateau is decoupled by differential motion across a decollement in the mid crust above which deformation is dominated by brittle reverse faulting and below which deformation occurs by viscous horizontal shortening and vertical thickening

contemporary crustal deformation around the southeast borderland of the tibetan plateau 1 we derive a detailed horizontal velocity field for the southeast borderland of the tibetan plateau using gps data collected from the crustal motion observation network of china between 1998 and 2004 our results reveal a complex deformation field that indicates that the crust is fragmented into tectonic blocks of various sizes separated by strike slip and transtensional faults most notably the regional deformation includes 10 11 mm yr left slip across the xianshuihe fault 7 mm yr left slip across the anninghe zemuhe xiaojiang fault zone 2 mm yr right slip across a shear zone trending northwest near the southern segment of the lancang river fault and 3 mm yr left slip across the lijiang fault deformation along the southern segment of the red river fault appears not significant at present time the region south and west of the xianshuihexiaojiang fault system whose eastward motion is resisted by the stable south china block to the east turns from eastward to southward motion with respect to south china resulting in clockwise rotation of its internal subblocks active deformation is detected across two previously unknown deformation zones one is located 150 km northwest of and in parallel with the longmenshan fault with 4 6 mm yr right slip and another is continued south southwestward from the xiaojiang fault abutting the red river fault with 7 mm yr left slip while both of these zones are seismically active the exact locations of faults responsible for such deformation are yet to be mapped by field geology comparing our gps results with predictions of various models proposed for tibetan plateau deformation we find that the relatively small sizes of the inferred microblocks and their rotation pattern lend support to a model with a mechanically weak lower crust experiencing distributed deformation underlying a stronger highly fragmented upper crust

geodetic measurement of crustal motion in southwest china global positioning system measurements performed over a 2 4 yr period confirm the xianshuihe xiaojiang fault system as one of the primary active structures in southwest china stations southwest of these faults show southerly motions of 5 15 mm yr relative to the western sichuan basin and stations in a 200 km geodetic network located northwest of the basin move at only 0 5 mm yr these results are consistent with clockwise rotation of southwestern sichuan and western yunnan about the eastern tibetan syntaxis accommodated by left lateral slip of 12 4 mm yr on the xianshuihe xiaojiang fault system the results imply that if eastward extrusion of crustal material from the plateau occurs at present it is not accommodated by east west shortening along the margin of the plateau and must involve wholesale eastward motion of low lying regions to the east

present day kinematics at the india asia collision zone the collision of the indian subcontinent with asia drives the growth and evolution of the greater tibetan plateau region fault slip rates resulting from the relative motion between crustal blocks can provide a kinematic description of the distribution of presentday deformation i construct a three dimensional regional scale elastic block model of the india asia collision zone that is consistent with geodetic observations of interseismic deforma tion mapped fault system geometry historical seismicity and the mechanics of the earthquake cycle this mechanical model of the elastic upper crust yields a set of kinematically consistent fault slip rates and block motions that may serve to constrain dynamic models of continental crustal dynamics

detrital supply from subduction accretion complexes to the eocene oligocene post collisional southern thrace basin nw turkey and ne greece abstract the thrace basin is a large mostly eocene oligocene post collisional sedimentary basin which developed following the closure of the vardar izmir ankara oceanic domain latest cretaceous paleocene sandstone petrologic data framework and heavy mineral analyses and the synthesis of preexisting and new sedimentological observations along representative stratigraphic sections show that the basin fill of the southern thrace basin was mostly derived from the izmir ankara and biga intra pontide subduction accretion complexes to the south proximal facies consistently show northward paleocurrents whereas most paleocurrent indicators measured downcurrent point to an eastward paleoflow likely the result of the deflection of primary gravity flows originated along the southern margin of the basin detrital contributions from the rhodopian basement complex to the west are virtually absent within the southern thrace basin fill conversely rhodopes derived eocene proximal facies in northeastern greece are characterized by a series of coarse grained fan deltas prograding eastward and likely feeding the basin plain turbidites of the depocentral portion of the thrace basin now concealed in the subsurface to the north of our study area arenites of the southern thrace basin are mostly lithic arkoses and arkosic litharenites provenance from the izmir ankara and biga suture zones to the south is characterized by ophiolitic granitoid gneissic low grade metamorphic and extrabasinal carbonate rock fragments as well as by picotite and glaucophane the application of detailed petrographic observations for discriminating paleo vs neovolcanic and penecontemporaneous vs noncoeval terrigenous sands lead to a substantial revision of the geodynamic interpretation of the thrace basin formerly considered a forearc basin a significant penecontemporaneous volcanic component is common in the upper eocene lower oligocene section and can be related to extensive post collisional volcanism following the closure of the vardar izmir ankara ocean the coexistence of pure neovolcanic layers crystal tuffs and cinerites and hybrid arenites rich in penecontemporaneous carbonate grains with sands derived from a continental basement and ophiolitic suites indicates the presence of episutural basins where shallow water carbonates were deposited on top of the exhuming subduction accretion prism these carbonates were mixed with penecontemporaneous neovolcanic and terrigeneous components and redeposited in deeper marine environments

the black sea basins structure and history new model based on new deep penetration regional seismic data part 2 tectonic history and paleogeography abstract a new lithostratigraphy scheme has been compiled for the western black sea basin and a new geological history scheme from middle jurassic till neogene is suggested for the entire black sea region continental rifting manifested itself from the late barremian to the albian while the time of opening of the basins with oceanic crust was from cenomanian till mid santonian origination of the western and eastern black sea basins took place almost simultaneously during cenozoic time numerous compressional and transpressional structures were formed in different part of the black sea basins it is shown that in pleistocene quaternary time turbidities mass transport deposits and leveed channels were being formed in the distal part of the danube delta

structural setting of the 2008 mw 7 9 wenchuan china earthquake the 2008 m w 7 9 wenchuan earthquake ruptured an imbricate thrust system in the longmen shan range which forms the eastern boundary of the tibetan plateau we use seismic reflection data and surface geology to construct geologic cross sections and a three dimensional 3d fault model in the range front the rupture was complex with slip on both the steeply dipping beichuan fault and the more shallowly dipping pengguan fault which appear to merge at depth in contrast only the beichuan fault ruptured in the north with the transition near a lateral fault offset thus the earthquake involved multiple thrust splays and breached a significant segment boundary to investigate the tectonic setting of the earthquake we extend our previous measurements of crustal shortening hubbard and shaw 2009 into the interior of the range and show that shortening correlates with topography this suggests that upper crustal shortening can produce the high topography of the longmen shan without calling on other uplift mechanisms based on this understanding we model the thrust belt as a critical taper wedge to assess what rock and fault strengths are required to explain the topographic slopes within the range front and basin the low taper within the basin is consistent with a weak detachment f 0 1 while a slightly stronger f 0 3 0 4 detachment is necessary to explain the higher taper of the range front this difference may relate to the localization of the detachment within a triassic evaporite sequence within the basin while the faults beneath the range front are rooted in precambrian metasedimentary or igneous rocks critical taper theory implies that shortening in the range front where the 2008 wenchuan earthquake occurred is many times greater than in the basin consistent with our shortening measurements we examine the implications of these findings for seismic hazard assessment in the region and in other active mountain belts around the world

critical taper model of fold and thrust belts and accretionary wedges the fold and thrust belts and submarine accretionary wedges that lie along compressive plate boundaries are one of the best understood deformational features of the earth s upper crust although there is considerable natural variation among the many fold and thrust belts and accretionary wedges that have been recognized and explored several features appear to be universal in cross section fold and thrust belts and accretionary wedges occupy a wedge shaped deformed region overlying a basal detachment or decollement fault the rocks or sediments beneath this fault show very little deformation the decollement fault characteristically dips toward the interior of the mountain belt or in the case of a submarine wedge toward the island arc the topography in contrast slopes toward the toe or deformation front of the wedge deformation within the wedge is generally dominated by imbricate thrust faults verging toward the toe and related fault bend folding two north american fold and thrust belts that exhibit these features are shown in figure 1 neither of these two examples is tectonically active today the southern canadian fold and thrust belt was active during the late jurassic and cretaceous 150 100 ma whereas the southern appa lachians were deformed during the late carboniferous to permian alle ghenian orogeny 300 250 ma figure 2 shows two examples that are currently active the taiwan fold and thrust belt produced by the sub duction of the eurasian plate beneath the philippine sea plate suppe 1981 1987 and the barbados accretionary wedge produced by the sub

active tectonics of the beichuan and pengguan faults at the eastern margin of the tibetan plateau the steep high relief eastern margin of the tibetan plateau has undergone rapid cenozoic cooling and denudation yet shows little evidence for large magnitude shortening or accommodation generation in the foreland basin we address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin the beichuan and pengguan faults are active dominantly dextral slip structures that can be traced continuously for up to 200 km along the plateau margin both faults offset fluvial fill terraces that yield inheritance corrected cosmogenic 10be exposure ages of 15 kyr indicating latest pleistocene activity the pengguan fault appears to have been active in the holocene at two sites along strike latest quaternary apparent throw rates on both faults are variable along strike but are typically 1 mm yr 1 rates of strike slip displacement are likely to be several times higher probably 1 10 mm yr 1 but remain poorly constrained late quaternary folding and dextral strike slip has also occurred along the western margin of the sichuan basin particularly associated with the present day mountain front these observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening they also suggest that activity on the margin parallel faults in eastern tibet may represent a significant seismic hazard to the densely populated sichuan basin

present day crustal motion within the tibetan plateau inferred from gps measurements 1 using the measurements of 726 gps stations around the tibetan plateau we determine the rigid rotation of the entire plateau in a eurasia fixed reference frame which can be best described by an euler vector of 24 38 0 42 n 102 37 0 42 e 0 7096 0 0206 ma the rigid rotational component accommodates at least 50 of the northeastward thrust from india and dominates the eastward extrusion of the northern plateau after removing the rigid rotation to highlight the interior deformation within the plateau we find that the most remarkable interior deformation of the plateau is a glacier like flow zone which starts at somewhere between the middle and western plateau goes clockwise around the eastern himalayan syntaxis ehs and ends at the southeast corner of the plateau with a fan like front the deformation feature of the southern plateau especially the emergence of the flow zone could be attributed to an eastward escape of highly plastic upper crustal material driven by a lower crust viscous channel flow generated by lateral compression and gravitational buoyancy at the later developmental stage of the plateau the first order feature of crustal deformation of the northeastern plateau can be well explained by a three dimensional elastic half space dislocation model with rates of dislocation segments comparable to the ones from geological observations in the eastern plateau although gps data show no significant convergence between the eastern margin of the plateau and the sichuan basin a small but significant compressional strain rate component of 10 5 2 8 nstrain yr exists in a relatively narrow region around the eastern margin in addition a large part of the eastern plateau northeast of the ehs is not undergoing shortening along the northeastward convergence direction of the ehs but is stretching

neotectonics of the min shan china implications for mechanisms driving quaternary deformation along the eastern margin of the tibetan plateau the min shan region located along the eastern margin of the tibetan plateau north of the sichuan basin provides an important natural laboratory in which to study the rates and patterns of deformation and their relationship to mountain building at the margin of the plateau the topographic margin of the plateau is coincident with a north trending mountain range the min shan that stands nearly 2 km above the mean elevation of the plateau 3500 m in this region we exploit the preservation of a series of variably deformed quaternary sediments along the western flank of the range to investigate the pleistocene holocene deformation field within the min shan region mapping and field observations of remnant alluvial fans of late pleistocene age indicate that deformation within the min shan involved substantial 10 rapid down to the northwest tilting the geometry of the deposits and the partial preservation of an erosion surface beneath the basin suggest that much of the modern relief of the min shan relative to the tibetan plateau is a consequence of this late pleistocene tilting rates of tilting inferred from luminescence dating of interbedded loess have been remarkably rapid 10 8 rad yr similarly rapid rates of holocene differential rock uplift are inferred from tilted lacustrine sediments in the southwestern part of the range the range is bounded on the west by the min jiang fault zone an east vergent reverse fault however holocene alluvial terraces in headwaters of the min river are preserved across the fault in several places indicating that displacement rates on the min jiang fault are 1 mm yr active faulting only occurs along the eastern foot of the range huya fault for a short distance 60 km despite 3 km of relief on the eastern range front the relationship between these structures and the tilting observed in the min jiang basin is enigmatic the faults do not appear to exert a strong control on the rates and pattern of deformation within the basin a simple flexural model demonstrates that rates of tilting on the western flank of the min shan are too high to be simply attributed to an isostatic response to surficial loading and unloading of the lithosphere present day horizontal shortening across the min shan is geodetically determined to be less than 2 3 mm yr suggesting that only a small part of the observed tilting can be attributed to horizontal shortening thus tilting and concomitant differential rock uplift in the min shan appear to require an additional driving component we suggest that quaternary deformation along the western min shan may reflect the surface response to thickening of a weak lower crust at the margin of the tibetan plateau

sedimentology and hydrocarbon habitat of the submarine fan deposits of the central carpathian paleogene basin ne slovakia abstract the central carpathian paleogene basin accommodates a subsiding area of the destructive plate margin the basin history comprises marginal faulting and alluvial fan accumulation e 2 transgressive onlap by shoreface sediments and carbonate platform deposits e 2 glacio eustatic regression induced by cooling terminal eocene event forced regression tectonic subsidence and growth fault accumulation of basin floor and slope fans e 3 decelerating subsidence aggradation and sea level rising during the mud rich deposition o 1 high magnitude drop in sea level mid oligocene event retroarc backstep of depocenters and lowstand accumulation of sand rich fans and suprafans o 2 m 1 subduction related shortening and basin inversion along the northern margins affected by backthrusting and transpressional deformation o 2 m 1 the basin fill sequence has poor toc 0 5 to fair toc

eocene stratigraphic evolution of the thrace basin turkey abstract this paper explains the primary basin evolution processes of the thrace basin which started opening during early middle eocene stratigraphic and tectonic models for different parts of the basin have been constructed and basin scale stratigraphic correlations were established by using outcrop well and seismic data initial deposits of eocene in the thrace basin show irregular depositional patterns associated with various lithofacies deposited under the control of various tectonostratigraphic settings first a compressional regime started after the collision of the sakarya continent with the rhodope pontide fragment in late cretaceous paleocene enabled initiation of transtensional stress which was responsible for the creation of necessary accommodation space for deposition of the initial thrace sediments in the northern and eastern part of the thrace basin the lower middle eocene hamitabat formation was deposited in this kind of transtensional setting and can be divided into various lithostratigraphic units an unconformity identified within hamitabat formation from seismic and well data divides it to two major units in early eocene the thrace basin was deepening eastwards and deposition was initiated between finger shaped paleo highs aligned in an e w direction thus synchronous erosional and depositional events in different parts of the basin formed various facies associated with a variety of depositional environments during the same time interval a regional unconformity at the base of lower eocene between karaagac and hamitabat formations can be correlated from south to north moreover the unconformity between lower middle eocene deposits and the middle eocene limestones of southern thrace is correlative with the unconformity between the hamitabat formation and overlying upper eocene limestones at northern regions this unconformity has a correlative conformity within the gazikoy or kesan formations in central thrace where continuous deposition took place during eocene without interruption

exploration plays in the turkish black sea turkey has the longest coastline on the black sea and controls the largest offshore portion of the exclusive economical zone unfortunately average water depths exceed 2000 m in most parts of the turkish sector and until recently exploration had been mainly restricted to the shelf to date only a few wells have been drilled in deep water

possible strand of the north anatolian fault in the thrace basin turkey an interpretation the north anatolian fault is a 1200 km long major transform fault bounding the anatolian plate on its north side the fault formed during the late middle miocene as a broad shear zone with a number of strands splaying westward in a horsetail pattern later movement became localized along a central strand and the southerly and northerly splays became inactive the west northwest striking thrace strike slip fault system is one of these right lateral presently inactive splays it consists of three subparallel strike slip faults from north to south these are the kirklareli luleburgaz and babaeski fault zones which extend for about 130 km through the thrace basin the thrace fault zone probably connected to the southeast with the presently active northern strand of the north anatolian fault in the marmara sea to the northwest the zone may have extended to the plovdiv graben zone in bulgaria the cenozoic thrace basin contains middle eocene to pliocene sedimentary rocks the thrace right lateral wrench fault system formed prior to the pliocene and had become inactive by the pliocene strike slip fault zones with normal and reverse separation are detected by seismic reflection profiles and subsurface data as the system became inactive the motion on the north anatolian fault zone began to be accommodated in the marmara sea region thus the thrace fault system represents the oldest strand of the north anatolian fault to the west of istanbul releasing bend extensional structures and restraining bend compressional structures are abundant along the fault zones several hydrocarbon producing anticlines lie en echelon to the luleburgaz fault zone regionally the thrace fault ystem has a horsetail shape with the various strands becoming younger southward

structural control on downdip locking extent of the himalayan megathrust author s lindsey eo almeida r mallick r hubbard j bradley k tsang llh liu y burgmann r hill em abstract 2018 the authors geologic reconstructions of the main himalayan thrust in nepal show a laterally extensive midcrustal ramp hypothesized to form the downdip boundary of interseismic locking using a recent compilation of interseismic gps velocities and a simplified model of fault coupling we estimate the width of coupling across nepal using a series of two dimensional transects we find that the downdip width of fault coupling increases smoothly from 70 to 90 km in eastern nepal to 100 110 km in central nepal then narrows again in western nepal the inferred coupling transition is closely aligned with geologic reconstructions of the base of the midcrustal ramp in central and eastern nepal but in western nepal the data suggest that the location is intermediate between two proposed ramp locations the result for western nepal implies either an anomalous coupling transition that occurs along a shallowly dipping portion of the fault or that both ramps may be partially coupled and that a proposed crustal scale duplexing process may be active during the interseismic period we also find that the models require a convergence rate of 15 5 2 mm year throughout nepal reducing the geodetic moment accumulation rate by up to 30 compared with earlier models partially resolving an inferred discrepancy between geodetic and paleoseismic estimates of moment release across the himalaya

integrated stratigraphy of the oligocene pelagic sequence in the umbria marche basin northeastern apennines italy a potential global stratotype section and point gssp for the rupelian chattian boundary the oligocene represents an important time period from a wide range of perspectives and includes significant climatic and eustatic variations the pelagic succession of the umbria marche apennines central italy includes a complete and continuous sequence of marly limestones and marls with volcaniclastic layers that enable us to construct an integrated stratigraphic framework for this time period we present here a synthesis of detailed biostratigraphic magnetostratigraphic and chemostratigraphic studies along with geochronologic results from several biotite rich volcaniclastic layers which provide the means for an accurate and precise radiometric calibration of the oligocene time scale from this study the interpolated ages for the rupelian chattian stage boundary located in the upper half of chron 10n at meter level 188 in the monte cagnero section and corresponding to the o4 o5 planktonic foraminiferal zonal boundary are 28 36 ma paleomagnetic interpolation 28 27 0 1 ma direct radioisotopic dating and 27 99 ma astrochronological interpolation these ages appear to be slightly younger than those reported in recent chronostratigraphic time scale compilations the monte cagnero section is a potential candidate for defining the chattian global stratotype section and point gssp and some reliable criteria are here proposed for marking the rupelian chattian boundary according to international union of geological sciences iugs recommendations

global positioning system measurements from eastern tibet and their implications for india eurasia intercontinental deformation we present and interpret global positioning system gps measurements of crustal motions for the period 1991 1998 for a network encompassing the eastern part of the tibetan plateau and its foreland relative to a eurasian frame defined by minimizing the velocities of 16 gps stations in europe central asia and siberia stations within all parts of the plateau foreland in south china move 6 10 mm yr east southeast indicating that the eastward movement within the plateau is part of a broader eastward movement that involves the plateau and its eastern and northern foreland north of the plateau foreland stations move northeastward at 10 mm yr indicating that the northern boundary of the deformation zone lies north of the plateau with this realization of a eurasian frame the velocity of the gps station at bangalore in southern india implies that the northward motion of india is 5 12 mm yr slower than that predicted from the nuvel 1a plate reconstruction viewed relative to the south china block stations of the northeast plateau bounded on the north by the qilian shan and the altyn tagh fault move nne to ne with velocities ranging from 19 mm yr within the plateau to 5 11 mm yr in its foreland the altyn tagh fault shows left lateral slip of 10 mm yr at 95 e and shortening across the fault of 5 mm yr stations south and west of the xianshuihe xiaojiang fault system define a crustal fragment rotating clockwise at 10 mm yr relative to the south china block around the eastern himalayan syntaxis the gps measurements indicate no significant shortening 3 mm yr within the longmen shan of the central eastern plateau and its adjacent foreland although the longmen shan rise over 6 km in 100 km horizontal distance geological studies indicate that the deformational field was established diachronously in late miocene to pliocene time was characterized by no east west shortening of tibetan crust and has an inhomogeneous style of deformation resulting from a balance of different tectonic processes

the role of fluidization in the emplacement of pyroclastic flows 2 experimental results and their interpretation abstract although often quoted as being important in the emplacement of pyroclastic flows little relevant experimental fluidization work has been done fluidization processes are first reviewed for a simple system against which ignimbrite samples can be compared results from fluidization experiments on ignimbrite samples show that their behaviour differs radically from any simple system principally because of their extremely poor sorting at a certain gas velocity u ie whose value cannot be predicted some ignimbrite samples begin to expand whilst at a higher gas velocity u mp the samples begin to show segregation structures the minimum fluidization velocity u mf in simple systems is replaced by u mp the value of the latter in pyroclastic materials cannot be easily or reliably predicted from published u mf correlations and a new empirical method for determining u mp is presented from the experimental data during fluidization ignimbrite samples expand much less than more conventional materials due to the bypassing of gas through segregation channels the total amount of expansion is also limited e g a 100 m thick pyroclastic flow will from fairly high gas velocities deflate to form an ignimbrite which is not less than 70 85 m thick during fluidization the poor sorting causes only part of the weight of the ignimbrite samples to be supported by the gas flow the degree of support increasing with an improvement in sorting segregation structures and grain size and compositional variations within fluidized ignimbrite samples show varying behaviour depending on the sorting of the sample after subjecting a sample to high gas velocities the net result is a grain size and compositionally zoned bed which becomes richer upwards in pumice and fine material once formed these features cannot be destroyed under laboratory conditions implying that some segregation structures should be present in any ignimbrite where u mp was exceeded

latest quaternary paleoseismology and slip rates of the longriba fault zone eastern tibet implications for fault behavior and strain partitioning 1 although much work has been done on active tectonics of eastern tibet little is known about the longriba fault zone and its role in strain partitioning whether its two sub parallel strands longriqu and maoergai faults can rupture simultaneously in a large earthquake remains unknown we conducted trenching combined with the interpretation of satellite imagery field investigations topographic surveys and radiocarbon and optically stimulated luminescence osl dating to reconstruct paleoseismic history and we used displaced terrace risers to estimate geological slip rates our results demonstrate that the longriba fault zone is predominantly right lateral with a small southeast verging thrust component four surface rupturing events occurred on the longriqu fault at 5080 90 11 100 380 13 000 260 and 17 830 530 cal yr b p together with our previous trenches on the maoergai fault we found that the last event probably ruptured both the longriqu and maoergai faults prior to the last event the two strands of the longriba fault zone experienced alternating earthquakes the fault zone has a high potential for an earthquake larger than mw 7 the slip rate of the longriba fault zone decreases from 7 5 mm yr in latest pleistocene to 2 1 mm yr in the holocene probably related to a slowing down of the eastern motion of the tibetan plateau the comparison with slip rates at the longmen shan fault zone suggests that the longriba fault zone has an equally important role in strain partitioning in eastern tibet this study is helpful to seismic hazard assessment and an understanding of deformation mechanism in eastern tibet

independent active microplate tectonics of northeast asia from gps velocities and block modeling 1 independent okhotsk and amurian microplate motions are tested using velocities from 123 gps sites 80 from within the proposed okh and amu plate boundaries used to constrain the plate kinematics of northeast asia a block modeling approach is used to incorporate both rigid block rotation and near boundary elastic strain accumulation effects in a formal inversion of the gps velocities models include scenarios with and without independent okh and amu plate motion our modeling favors scenarios with independent okh and amu motion based on the application of f test statistics the independent okh plate rotates 0 231 deg myr clockwise with respect to north america about a pole located north of sakhalin the modeled amu plate rotates 0 298 deg myr counterclockwise with respect to nam about a pole located west of the magadan region the plate motion parameters of the independent plates are consistent with the kinematics inferred from earthquake focal mechanism solutions along their boundaries

contemporary crustal deformation within the pamir plateau constrained by geodetic observations and focal mechanism solutions we used an updated data set of 192 gps derived surface velocities and 393 earthquake focal mechanisms mw 3 0 hypocenter depths 30 km to evaluate the spatial variations in the surface strain rate and crustal stress regime throughout the pamir plateau and its surrounding regions the strain rate field was estimated using the spline in tension approach that solves for the surface velocity in a rectangular grid and the stress field was predicted from focal mechanism solutions using the damped regional scale stress inversion drssi method of hardebeck and michael journal of geophysical research https doi org 10 1029 2005jb004144 2006 the results show that the crustal stress field around the pamir plateau is predominantly characterized by nnw sse compression and e w extension which is consistent with the principal orientations of the two dimensional surface strain rate tensor this agreement supports the notion that the pamir and southwestern tien shan are uniformly strained blocks in particular the fan shaped rotational pattern between text shmax and the strain rate from the western pamir to the tajik basin shows that the counterclockwise rotation of the text shmax orientation is associated with vertical deformation which is consistent with the idea of schurr et al tectonics 33 8 2014tc003576 2014 concerning the gravitational collapse and westward extrusion of the crust in the western pamir we propose that such a stress strain pattern dominated by nnw ese oriented compression and e w trending extension originated from a combination of the northward push of the indian continent and the southward subduction of the tien shan

slip maxima at fault junctions and rupturing of barriers during the 2008 wenchuan earthquake the devastating wenchuan earthquake in 2008 struck along a fault zone that showed low rates of deformation analysis of gps and insar data suggests that as structural barriers failed during a single earthquake the rupture cascaded across multiple fault segments which may explain the high magnitude of the event

imaging the crustal structure beneath the eastern tibetan plateau and implications for the uplift of the longmen shan range abstract competing models have been proposed to account for the unusual uplift of the longmen shan fault zone in the eastern tibetan plateau and resulting hazards however due to the terrain and thick sedimentary cover the crustal structure of the eastern tibetan plateau remains uncertain therefore testing these models has been difficult in 2011 a 310 km long se trending sinoprobe 02 deep seismic reflection profile was recorded in easternmost tibet in order to study its regional crustal structure the resulting image revealed the detailed crustal structure of eastern tibet which when combined with geological gps global positioning system and geochemical evidence strongly suggests that yangtze sub continent crust extends beneath the region the seismic profile also images the tremendously thick triassic sedimentary cover in the songpan ganzi terrane sgt these triassic sediments vary considerably in thickness across several crustal blocks in addition both the longriba fault zone of the northeastern sgt and the longmen shan fault zone show strong intracrustal reflections that terminate at a depth coinciding largely with the crust mantle boundary moho accordingly we propose a new tectonic model based on an integrated analysis of this seismic reflection profile and previous gps measurements in this model crustal scale deformation is suggested to have participated in the oblique extrusion and uplift of the easternmost edge of the tibetan plateau along the longmen shan in a broader context the lithospheric configuration imaged by the seismic reflection profile will advance our understanding of the tectonic response of the eastern tibetan plateau to the ongoing india eurasia collision and has new implications for the estimating seismic risk in the region

active thrusting of the longquan fault in the central sichuan basin china and the seismotectonic behavior in the longmen shan fold and thrust belt present day convergence within the longmen shan fold and thrust belt lsftb was released by the 2008 mw 7 9 wenchuan earthquake which ruptured multiple thrust ramps beneath the range front structures however it is still unclear whether fault slip propagated eastward into the foreland closer to densely populated areas around chengdu in this study we provide constraints on the 3 d subsurface structure fault activity and seismic hazards of the longquan fault located in the central sichuan basin 100 km east of the range front structures of the lsftb we develop a seismotectonic model and assess the activity of the longquan fault by a combination of methods including interpretation of seismic reflection profiles analysis of satellite images field mapping trench logging and radiocarbon dating our survey reveals that at least two surface rupturing events occurred on the longquan fault in the holocene our 3 d structural model and evidence for late holocene faulting events on the longquan fault reveals that upper crustal shortening in the sichuan basin is accommodated by a frontal thrust system that is linked to the recently active range front blind structures by a shallow detachment we suggest that dynamic weakening following fault activity at the longmen shan range front might unlock the up dip portion of this shallow detachment sending slip eastward into the foreland and to the surface along the longquan thrust ramps our results have important implications for seismic hazards assessment of active frontal thrusts linked by upper crustal detachments in active fold and thrust belts around the world

co seismic thrusting rupture and slip distribution produced by the 2008 mw 7 9 wenchuan earthquake china field investigations reveal that the mw 7 9 wenchuan china earthquake of 12 may 2008 produced a 285 km long surface rupture zone with dominantly thrusting slip accompanied by a right lateral component along the central northern segments of the zone and left lateral component along the southern segment along the longmen shan thrust belt eastern margin of the tibetan plateau the co seismic ruptures mainly occurred along the pre existing yingxiu beichuan guanxian anxian and qingchuan faults which are the main faults of the longmen shan thrust belt the displacements measured in the field are approximately 0 5 6 5 m in the vertical typically 1 3 m accompanied by an average left lateral component of 2 m along the 50 km long southernmost segment of the rupture zone and an average right lateral component of 1 m along the 150 km long central northern segments the maximum thrust slip amount is estimated to be 10 m accompanied by 9 m of shortening across the rupture zone this finding is consistent with estimates based on seismic data the rupture length and maximum vertical displacement are the largest among all intracontinental thrust type earthquakes reported to date our findings demonstrate that i the wenchuan earthquake occurred upon pre existing active faults of the longmen shan thrust belt thereby controlling the spatial distribution of co seismic surface rupture and displacement and the rupture processes of the earthquake ii the long rupture length and large thrusting slip resulted from compressive stress associated with eastward extrusion of the tibet plateau as it accommodates the ongoing penetration of the indian plate into the eurasian plate and iii present day shortening strain upon the eastern margin of the tibetan plateau is mostly released by seismic slip along thrust faults within the longmen shan thrust belt

rupture of deep faults in the 2008 wenchuan earthquake and uplift of the longmen shan the longmen shan mountains rise up 6 000 m over a distance of just 100 km but the mechanisms driving formation of this striking topography are debated analyses of crustal movements during the 2008 wenchuan earthquake suggest that fault induced uplift plays a role in building the high topography

coseismic reverse and oblique slip surface faulting generated by the 2008 mw 7 9 wenchuan earthquake china the mw 7 9 wenchuan china earthquake ruptured two large thrust faults along the long menshan thrust belt at the eastern margin of the tibetan plateau this earthquake generated a 240 km long surface rupture zone along the beichuan fault and an additional 72 km long surface rupture zone along the pengguan fault maximum vertical and horizontal offsets of 6 5 m and 4 9 m respectively were measured along the beichuan fault a maximum vertical offset of 3 5 m was measured along the pengguan fault coseismic surface ruptures integrated with aftershocks and industry seismic profiles show that two imbricate structures have ruptured simultaneously resulting in the largest continental thrust event ever documented large oblique thrusting observed during this earthquake indicates that crustal shortening is an important process responsible for the high topography in the region as everywhere along the edge of tibetan plateau

active faulting and block movement associated with large earthquakes in the min shan and longmen mountains northeastern tibetan plateau the min shan and central and southern parts of the longmen mountains form the middle segment of the north trending earthquake zone at the eastern edge of the tibetan plateau the min shan mountains are a cenozoic to quaternary uplift zone that has undergone south directed block movements to produce the 1933 diexi earthquake m 7 5 on the min jiang fault and the 1976 songpan earthquake swarm m 7 2 6 7 7 2 on the huya fault the min jiang fault on the western boundary of the uplift zone is dominated by reverse movement with a right lateral component the huya fault on the eastern margin of the min shan uplift zone is also dominated by reverse movement but is associated with a left lateral component

rapid slip deficit rates at the eastern margin of the tibetan plateau prior to the 2008 m w 7 9 wenchuan earthquake the longmen shan is the steepest topographic front at the india asia collision zone and the site of the mw 7 9 wenchuan earthquake here to explain the interseismic gps velocities across the greater longmen shan region we develop a boundary element model including earthquake cycle effects topography the westward dipping beichuan fault and a 20 km deep shallowly dipping detachment inferred from observed afterslip and from structural considerations previous analyses which neglected the detachment and earthquake cycle effects have found shortening rates near zero in contrast we find that interseismic gps data are consistent with a shortening rate of 5 7 1 5mm yr and maximum surface slip deficit rate of 9 5 2 5mm yr this model unifies the interpretation of geodetic deformation throughout the earthquake cycle and suggests that the longmen shan is an active fold and thrust belt with of wenchuan like recurrence intervals as short as 600 years

genesis of the eastern paratethys manganese ore giants impact of events at the eocene oligocene boundary abstract the giant mn ore deposits of the paratethys are located on the slopes and or margins of deep basins the eocene ocean and associated basins were strongly influenced by large scale submarine hydrothermal activity which supplied prodigious amounts of ca co2 sio2 mn and other components to the oceans this caused a substantial shift in seawater composition and resulted in the deposition of carbonates as well huge amounts of mn the giant mn ore deposits of the eastern paratethys were formed as a consequence of the early oligocene global transgression in shelf environments of marginal and epicontinental seas frequently with anoxic regime of the bottom water

differential strain transfer longmen shan thrust belt eastern tibetan plateau margin implications for seismic hazards abstract southeastward strain transfer in the middle southern longmen shan lms thrust belt not only can promote the development of fault related folds and earthquakes in the piedmont but also affect the seismogenic capacity of the middle southern lms thrust belt however the detailed transfer process remains elusive in this work we combine structural profile re analysis sandbox modeling and seismic statistics to illustrate the strain transfer process our main results indicate that 1 the thickness of the shallow detachment e g middle lower triassic gypsum salt strata is probably the main factor for differences in southeastward strain transfer within the domain between the middle southern lms thrust belt and weiyuan moxi anticline this is also supported by our sandbox model 2 the seismogenic capacity in the southern lms thrust belt is probably proportional to the corresponding shortening of the range front blind thrust rfbt thus seismogenic capacity in the seismic gap zone is weaker than those of other segments of the southern lms thrust belt which is probably

subduction initiation and the rise of the shillong plateau abstract discrepancies between geodetically and geologically estimated thrust fault slip rates are generally viewed as a methodological problem even when slip rate is steady over geological time a discrepancy may exist because each method is sensitive to different deformation processes however this offers a tool to estimate the partitioning of convergence between footwall and hanging wall deformation and therefore a way to discriminate among orogenic styles here we investigate one such discrepancy for the shillong plateau a basement cored contractional orogen within the himalayan foreland basin using a regional block model to explain the modern geodetic velocity field and explicit uncertainty analysis of the geologic rates we show that this discrepancy cannot be reconciled simply by invoking uncertainties in individual methods our results indicate that the shillong plateau is not an ongoing forward break of the bhutan himalayas as was believed until recently instead the observed inter plate convergence and plateau uplift in this region may be driven primarily by an attempt of the negatively buoyant indian passive margin lithosphere the surma basin south of the plateau to initiate subduction as a result the uplift history of the plateau which constrains the geologic rate is significantly lower than expected given the geodetic convergence rate we propose that this convergence is largely accommodated by the transport of the footwall into the mantle this geodynamic scenario has important regional seismotectonic implications 1 the cold and brittle sinking passive margin may have enabled the deep extent 30 km and therefore large magnitude of the mw 8 shillong earthquake of 1897 2 the collapse of the indian lithosphere into the mantle may have created the anomalously deep 20 km surma basin and 3 this subsidence may also drive accelerated post miocene westward propagation of the indo burman wedge we propose that the shillong plateau is the only modern example of passive margin collapse and can serve as a natural laboratory to study the earliest phase of subduction

structural interpretation of the coseismic faults of the wenchuan earthquake three dimensional modeling of the longmen shan fold and thrust belt 1 the 2008 mw 7 9 wenchuan earthquake is a result of ongoing india tibet collision and reflects the growth of the longmen shan fold and thrust belt in this paper we construct a 3 d structural model of the geometry of the coseismic faults and related structures of the wenchuan earthquake by integrating geological investigations relocated aftershocks and seismic reflection profiles in the 3 d structural model the differences between the southern and northern segments of the rupture are highlighted the structural transition zone between the two segments contains a major geometric segment boundary reflecting differences in the structural configuration of the thrust ramp and the tectonic evolution of the fault system which appears to have localized significant damage from anxian to beichuan within the northern segment we identify a transverse structure across which the beichuan fault plunges under the tangwangzhai syncline this boundary corresponds to a marked change in the nature of the surface rupture and is illuminated by a microearthquake sequence perpendicular to the longmen shan thrust belt in the southern segment our investigations confirm that uplift due to active faulting and folding is largely responsible for the areas of steepest topography on the basis of this association the southwestern segment of the longmen shan south of the wenchuan earthquake is likely active and presents a significant earthquake hazard despite the lack of historical earthquakes in this region this study illustrates the importance of building 3 d models to study active faulting and folding as well as to assess earthquake hazard

sedimentation and diagenesis of an oligocene manganese deposit in a shallow subbasin of the paratethys thrace basin turkey abstract the northern part of the thrace basin intermittently connected to the paratethys seaway was the site of micritic carbonate sedimentation during the eocene pisolite and coarse shell debris in the earliest oligocene and clastic sediments through into the neogene near the transition from carbonate to clastic facies thin and discontinuous manganese ores at binkilic consist of interlayers of dominantly oxide and lesser carbonate minerals these occur as disseminated pisolitic oolitic concretionary and massive forms chief ore minerals are pyrolusite manganite cryptomelane rhodochrosite and kutnahorite in thin and polished sections mn carbonates in originally calcite monaxon sponge spicules are seen to have been replaced by mn oxides thus documenting the introduction of dissolved mn and major diagenetic alteration of primary calcite to mn carbonate and finally to mn oxide throughout the ore sequence the rees show pronounced positive eu and small negative ce anomalies carbon isotopes in the sequence show a narrow range of values from about 5 to 7 pdb within the range characterizing modern fresh waters the ore body formed during a marine regression and it was positioned adjacent to an embayment in the basin margin facts which support the hypothesis that the ore fluid was groundwater draining from mn bearing rocks of the nearby stranjha massif at a time when the basin was cut off from the paratethys this scenario thus differs significantly from that suggested for penecontemporaneous paratethyan mn deposits redox controlled primary precipitation of oxides and carbonates in segregated environments

triggered slip on a back reverse fault in the mw6 8 2013 lushan china earthquake revealed by joint inversion of local strong motion accelerograms and geodetic measurements abstract the 2013 mw6 8 lushan china earthquake occurred in the southwestern end of the longmenshan fault zone we jointly invert local strong motion data and geodetic measurements of coseismic surface deformation including gps and insar to obtain a robust model of the rupture process of the 2013 lushan earthquake our joint inversion best model involves the rupture of two opposing faults during the lushan earthquake a main fault and a secondary fault it is only when the secondary fault is included that both the gps and insar measurements are fit along with the near field strong motion over 75 of the computed moment was released in slip on the main fault segment a northwest dipping listric thrust fault with buried thrust and dextral strike slip at hypocenter depths and with only minor slip closer to the surface the secondary fault mainly involved oblique thrust slip or pure dextral strike slip at shallower depths and accounts for just under 24 of the moment released in the lushan earthquake coulomb stress changes of about 0 5 mpa on the secondary fault segment at the time coseismic slip initiated on that fault indicate that slip was likely triggered by the coseismic slip on the main blind thrust fault our coseismic slip model is consistent with a sub horizontal and east west to southeast northwest trending most compressive stress our inferred coseismic slip model is also consistent with previous gps derived models of strain accumulation on the longmenshan fault system

depositional environment and hydrocarbon source potential of the oligocene ruslar formation kamchia depression western black sea abstract the oligocene ruslar formation is a hydrocarbon source rock in the kamchia depression located in the western black sea area depositional environment and source potential of the predominantly pelitic rocks were investigated using core and cuttings samples from four offshore wells in these wells the ruslar formation is up to 500 m thick based on lithology and well logs the ruslar formation is subdivided from base to top into units i vi dysoxic to anoxic conditions and mesohaline to euhaline salinities prevailed during deposition of the ruslar formation relatively high oxygen contents occurred during early solenovian times lower part of unit ii when brackish surface water favoured nannoplankton blooms and the deposition of bright marls solenovian event anoxic conditions with photic zone anoxia were established during late oligocene times units iii and iv and probably reflect a basin wide anoxic event in the eastern paratethys during kalmykian times organic carbon content in the ruslar formation is up to 3 autochthonous aquatic and allochthonous terrigenous biomass contribute to the organic matter relatively high amounts of aquatic organic matter occur in the lower part of the ruslar formation units i and ii and in its upper part unit vi diatoms are especially abundant in the lower part of unit vi the kerogen is of type iii and ii with hi values ranging from 50 to 400 mghc gtoc units i and ii pshekian lower solenovian are characterized by a fair to good potential to produce gas and oil but potential sources for gas and oil also occur in the upper oligocene units iv vi

from tethys to eastern paratethys oligocene depositional environments paleoecology and paleobiogeography of the thrace basin nw turkey the oligocene depositional history of the thrace basin documents a unique paleogeographic position at a junction between the western tethys and the eastern paratethys as part of the tethys shallow marine carbonate platforms prevailed during the eocene subsequently a three staged process of isolation started with the oligocene during the early rupelian the thrace basin was still part of the western tethys indicated by typical western tethyan marine assemblages the isolation from the tethys during the early oligocene is reflected by oolite formation and endemic eastern paratethyan faunas of the solenovian stage the third phase reflects an increasing continentalisation of the thrace basin with widespread coastal swamps during the late solenovian the mollusc assemblages are predominated by mangrove dwelling taxa and the mangrove plant avicennia is recorded in the pollen spectra the final continentalisation is indicated by the replacement of the coastal swamps by pure freshwater swamps and fluvial plains during the late oligocene mammal zone mp 26 this paleogeographic affiliation of the thrace basin with the eastern paratethys after 32 ma contrasts all currently used reconstructions which treat the basin as embayment of the eastern mediterranean basin

the geological evolution of the tibetan plateau the geological evolution of the tibetan plateau is best viewed in a context broader than the india eurasia collision zone after collision about 50 million years ago crust was shortened in western and central tibet while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western pacific and indonesia cessation of rapid pacific trench migration 15 to 20 million years ago coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern tibet the latter appear to result from rapid eastward flow of the deep crust probably within crustal channels imaged seismically beneath eastern tibet these events mark a transition to the modern structural system that currently accommodates deformation within tibet

simulating the recent evolution of the southern big bend of the san andreas fault southern california 1 the southern big bend of the san andreas fault has been interpreted to have successively abandoned two strands the mission creek and mill creek strands of the san andreas fault during the past 1 ma before taking up activity along its present day configuration this evolution is simulated within three dimensional models to explore the hypothesis that fault systems evolve to increase mechanical efficiency the three dimensional boundary element method models are validated by comparison of modeled fault slip rates and uplift rates with geologic data the model results match well the geologic strike slip rates and uplift patterns overestimation of reverse slip rates along the northern san bernardino mountains may reflect model assumptions of fault geometry the partitioning of slip among active faults changes between the three phases of southern san andreas fault evolution revealing 1 a trade off in strike slip rates between the san jacinto and san andreas faults 2 a trade off between strike slip rates on the san andreas fault and reverse slip along faults associated with uplifting the san bernardino mountains and 3 a trade off in strike slip rates along the san andreas and strike slip rates along the eastern california shear zone mechanical efficiency of the entire model increases from the mission creek to mill creek fault configuration and decreases from the mill creek configuration to the present day configuration the decrease in mechanical efficiency with the transition to the present day fault geometry may reflect gaps in our understanding of tectonic loading and or fault geometry

microplate model for the present day deformation of tibet 1 site velocities from 349 global positioning system gps stations are used to construct an 11 element quasi rigid block model of the tibetan plateau and its surroundings rigid rotations of five major blocks are well determined and average translation velocities of six smaller blocks can be constrained where data are well distributed the velocity field can be explained well by rigid block motion and fault slip across block boundaries residual misfits average 1 6 mm yr compared to typical one standard deviation velocity uncertainties of 1 3 mm yr any residual internal straining of the blocks is small and heterogeneous however residual substructure might well represent currently unresolved motions of smaller blocks although any smaller blocks must move at nearly the same rate as the larger blocks within which they lie undetected relative motions between them could be significant particularly where there are gaps in gps coverage predicted relative motions between major blocks agree with the observed sense of slip and along strike partitioning of motion across major faults however predicted slip rates across tibet s major strike slip faults are low only 5 12 mm yr a factor of 2 3 smaller than most rates estimated from fault offset features dated by radiometric methods as 2000 to 100 000 year old previous work has suggested that both gps data and low fault slip rates are incompatible with rigid block motions of tibet the results reported here overcome these objections

a dislocation model of strain accumulation and release at a subduction zone strain accumulation and release at a subduction zone are attributed to stick slip on the main thrust zone and steady aseismic slip on the remainder of the plate interface this process can be described as a superposition of steady state subduction and a repetitive cycle of slip on the main thrust zone consisting of steady normal slip at the plate convergence rate plus occasional thrust events that recover the accumulated normal slip because steady state subduction does not contribute to the deformation at the free surface deformation observed there is completely equivalent to that produced by the slip cycle alone the response to that slip is simply the response of a particular earth model to embedded dislocations for a purely elastic earth model the deformation cycle consists of a coseismic offset followed by a linear in time recovery to the initial value during the interval between earthquakes for an elastic viscoelastic earth model elastic lithosphere over a viscoelastic asthenosphere the postearthquake recovery is not linear in time records of local uplift as a function of time indicate that the long term postseimic recovery is approximately linear suggesting that elastic earth models are adequate to describe the deformation cycle however the deformation predicted for amore simple elastic half space earth does not reproduce the deformation observed along the subduction zones in japna at all well if stick slip is restricted to the main thrust zone as recognized earlier by shimazaki seno and kato the uplift profiles could be explained if stick slips were postulated to extend along the plate interface beyond the main thrust zone to a depth of perhaps 100 km but independent evidence suggests that stick slip at such depths if unlikely less

present day crustal vertical movement inferred from precise leveling data in eastern margin of tibetan plateau abstract we collect precise leveling data observed in the period of 1970 to 2012 around the eastern margin of the tibetan plateau and process the data to acquire present day crustal vertical velocity field vertical rates of 9 gps sites are employed as a priori constraints to define the reference frame the velocity field shows that most of the regions in the eastern margin of the tibetan plateau are undergoing uplift the gongga shan and west qinling are uplifting at maximum rates of 5 8 1 0 mm a and 6 0 1 3 mm a respectively a 2 d buried dislocation model is used to infer normal or reverse dip slip rates the result indicates that the reverse slip rate along the longmen shan fault is 4 2 0 5 mm a followed by the daliangshan and longriba faults with the rates of 3 7 0 5 mm a and 2 8 0 3 mm a respectively thezemuhe and northern section of the xiaojiang fault have the normal slip rates of 2 3 1 0 mm a and 2 9 0 4 mm a respectively combining vertical velocity field with gps derived horizontal velocity field we investigate the characteristics of crustal movement and dynamic mechanism the 3d velocity field indicates that the helan shan is uplifting and the yinchuan graben is subsiding the 3d crustal movement of the liupan shan region is segmented with the area in the vicinity of the northern liupan shan fault uplifting and the area in the vicinity of southern liupan shan fault subsiding respectively the subsidence of the central and southern sichuan yunnan terrain is caused by the near east west extension the budget of horizontal material influx suggests that movements of the upper and lower crust are rather different in most of the region excessive material influx into the lower crust upper mantle underneath most of the sub blocks seems required to maintain the uplift rates inferred from leveling providing evidence for the existence of lower crustal flow in this region

structural framework of onshore and offshore avcilar istanbul under the influence of the north anatolian fault summary to investigate the onshore offshore structural framework of the northern shelf of the sea of marmara a multidisciplinary study was carried out including multichannel and singlechannel seismicreflection profiling multibeam bathymetry sounding side scan sonar imaging on offshore as well as land studies for s wave velocity estimation by passive and active array measurements and monitoring of block deformations by global positioning system gps based on the multidisciplinary data possible interactions between landslides and active faulting have been reviewed and their possible relation to the north anatolian fault zone nafz has been discussed it is observed that structurally the most deformed subsurface zone offshore coincides with the most undulated landform due to landslides in the area this observation leads to idea that the structural complexities of the area may also contribute to land sliding as much as other contributing mechanisms such as slope instability shallow groundwater level lithology and

the black sea basins structure and history new model based on new deep penetration regional seismic data part 1 basins structure and fill abstract this work is based upon results of interpretation of about 8872 km long regional seismic lines acquired in 2011 within the international project geology without limits in the black sea the seismic lines cover nearly the entire black sea basins including russia turkey ukraine romania and bulgaria sectors a new map of acoustic basement relief and a new tectonic structure scheme are constructed for the black sea basins the basement of the black sea includes areas with oceanic crust and areas with highly rifted continental crust a chain of buried seamounts which were interpreted as submarine volcanoes of late cretaceous santonian to campanian age has been identified to the north of the turkish coast on the shatsky ridge probable volcanoes of albian age have also been recognized synorogenic turbidite sequences of paleocene eocene and oligocene ages have been mapped in the cenozoic numerous compressional and transpressional structures were formed in different parts of the black sea basin during the pleistocene quaternary turbidites mass transport deposits and leveed channels were formed in the distal part of the danube delta

slip rate gradients along the eastern kunlun fault 1 whether strike slip fault systems in eurasia accomplish eastward extrusion of tibetan crust and lithosphere depends largely on the kinematics of deformation at the fault tip here we present new slip rate determinations using millennial scale geomorphic markers from sites along the easternmost segment of the kunlun fault in north central tibet this fault system represents one of the major strike slip faults within the indo asian collision zone has been argued to exhibit uniform slip rates along much of its length and plays a central role in models for eastward extrusion of tibetan lithosphere displaced fluvial terrace risers along tributaries of the yellow river coupled with 14c ages of terrace material provide constraints on slip rates over late pleistocene to holocene time results indicate that slip rates decrease systematically along the eastern 150 km of the fault from 10 to 2 mm yr these data challenge the view that slip along the kunlun fault remains uniform along the entire length of the fault and instead reveal gradients in displacement similar to those expected at fault tips moreover slip along the fault appears to terminate within the thickened crust of the plateau and therefore any extrusion of tibetan lithosphere accomplished by slip along the kunlun fault must be absorbed by internal deformation of the plateau surrounding the fault tip

eocene oligocene stratigraphy and structural history of the karaburun area southwestern black sea coast turkey transition from extension to compression the stratigraphic succession exposed in the karaburun area southern black sea coast nw turkey records multiple changes in depositional and tectonic settings during cenozoic times it starts with the middle upper eocene sogucak formation of reef limestone that across a normal fault omitting the lower part of the lower oligocene ceylan formation deep marine shale unit abuts the upper part of the ceylan formation that is made up of two facies 1 shallow marine sandstone and 2 shallow marine limestone units containing horizons of submarine slumps both facies are unconformably overlain by the fluvial upper miocene cukurcesme formation the tectonic record includes 1 latest eocene early oligocene ne sw extension 2 early oligocene ne sw shortening and 3 late miocene nw ne extension the earliest normal faults cutting the sogucak and the lower part of the ceylan formations are associated with clastic dykes injected into the deep marine shale these structures suggest a disruption of the eocene carbonate platform and are also known in the neighbouring thrace basin the following ne sw shortening created the ne vergent karaburun thrust that is synchronous with the shallowing and inversion of the ceylan basin rotation of the stress field is recorded by changes in clastic dyke orientation and their deformation compression caused multiple westerly directed submarines slides from uplifts in easterly located regions this event is not recorded in the thrace basin finally the miocene tectonic activity formed nw and ne striking normal faults the outlined tectonic history includes early oligocene extensional and compressional episodes recorded in the southern margin of the black sea that had hitherto not been known

partitioning of localized and diffuse deformation in the tibetan plateau from joint inversions of geologic and geodetic observations abstract the spatial complexity of continental deformation in the greater tibetan plateau region can be defined as the extent to which relative motion of the indian and asian plates is partitioned between localized slip on major faults and distributed deformation potency rates provide a quantitative metric for determining the magnitudes of diffuse and on fault crustal deformation which are proportional to strain rates within crustal micro plates and fault slip rates respectively we simultaneously estimate micro plate rotation rates interseismic elastic strain accumulation fault slip rates on major structures and strain rates within 24 tectonic micro plates inferred from active fault maps in the greater tibetan plateau region using quasi static block models constrained by interseismic surface velocities at 731 gps sites and 9 holocene late quaternary geologic fault slip rates the joint geodetic geologic inversion indicates that geologic slip rates are kinematically consistent with differential micro plate motions estimated left lateral slip rates on the altyn tagh west central kunlun and xianshuihe faults are relatively homogeneous along strike 11 5 10 5 and 11 mm yr respectively while segmentation of the eastern kunlun fault by the intersecting elashan and riyueshan faults results in a decreased slip rate consistent with geologic observations the fraction of total potency rate associated with intrablock strain uncorrected for observational noise ranges from 0 27 in the himalayan range block to 0 91 in the aksai chin block monte carlo simulations are used to quantify the likelihood that internal deformation is statistically distinguishable from the uncertainties in geodetic velocities these simulations indicate that internal block deformation is statistically significant only within the himalayan range front where internal deformation accounts for id 0 11 of block potency rate budget west central plateau id 0 68 ganzi yushu xianshuihe 0 58 burma 0 09 jiali 0 38 and aksai chin 0 68 blocks in the other 18 tectonic micro plates within the plateau region estimated internal block potency is not currently distinguishable from the expected contribution of observational noise to residual velocities of the total potency budget within the tibetan plateau 85 is taken up by slip on major faults with the remaining 15 accommodated by internal processes at sub block scale distinguishable from observational noise the localization of the majority of plate boundary activity is also supported by the spatial distribution of modern and historical crustal earthquakes sixty seven percent of the total moment released by earthquakes in the cmt catalog and 90 of historical moment since 1900 have been released within 25 km of the major faults included in the block model representing only 12 of the characteristic half block length scale of 215 km the localization of deformation inferred from geologic geodetic and seismic observations suggests that forces applied to tectonic micro plates drive fault system activity at the india asia collision zone over decadal to quaternary time scales

paleoseismic evidence and repeat time of large earthquakes at three sites along the longmenshan fault zone abstract in historical records no earthquake of magnitude comparable with that of the wenchuan mw 7 9 earthquake has ever been reported in chengdu and longmenshan regions it is important therefore to assess if there is any evidence of prior large earthquakes in the recent geological record in order to explore this problem 3 trenches were excavated separately at 3 sites along the surface rupture zones in the middle segment of the beichuan yingxiu fault and jiangyou guanxian fault of the longmenshan fault zone and the offsets of geomorphic surfaces were measured in the trenches the basic facts of recurrence of large earthquake on the seismogenic fault of the wenchuan earthquake are demonstrated in this paper on the basis of the accumulated deformation amounts of old and young geomorphic surfaces as well as the paleoearthquake events revealed in the trenches the document that at leigu along the beichuan yingxiu fault at bailu along the jiangyou guanxian fault and xiaoyudong on a nw trending fault the height of fault scarp on the second terrace has a multiple relationship to that on the first terrace after the wenchuan earthquake of 12 may the elevation difference of the marker horizon the yellow sandy clay bed of the second terrace revealed in the trenches on both sides of the fault is nearly twice or three times larger in bailu of that produced by the wenchuan earthquake these observations suggest the occurrences of paleoearthquake events with surface deformation comparable to that produced by the wenchuan mw 7 9 earthquake according to the dating data and the fact that there is no such slip of comparable paleoearthquakes in the 2300 year long historic literature in longmenshan region we suggest that the penultimate event occurred between 2300 a bp and 3300 a bp

the longriqu fault zone eastern tibetan plateau segmentation and holocene behavior the dextral longriba fault system lfs 300 km long and constituting of two fault zones has recently been recognized as an important structure of the eastern tibetan plateau sichuan province as it accommodates a significant amount of the deformation induced by the ongoing indo asian collision although previous paleoseismological investigations highlighted its high seismogenic potential no systematic quantification of the dextral displacements along the fault system has been undertaken so far as such information is essential to appraise fault behavior we propose here a first detailed analysis of the segmentation of the longriqu fault the northern fault zone of the lfs and an offset inventory of morphological features along the fault using high resolution pleiades satellite images we identify six major segments forming a mature fault zone offsets inventory suggests a characteristic coseismic displacement of 4 m two alluvial fans with minimum ages of 6 7 and 13 2 ka respectively displaced by 23 7 m and 40 5 m give an estimate of the maximal horizontal slip rate on the longriqu fault of 3 2 1 1 mm yr a1 as a result a minimum 1340 year time interval between earthquakes is expected

active fault related folding beneath an alluvial terrace in the southern longmen shan range front sichuan basin china implications for seismic hazard abstract the devastating 2008 m w 7 9 wenchuan earthquake china demonstrates that the central and northern parts of the longmen shan are currently active evidence for active faulting and folding in the southern longmen shan however remains poorly documented in this paper we define the structural geometry fault kinematics and seismic hazard of the qiongxi thrust fault system qtf along the southern longmen shan range front by integrating deep and shallow seismic reflection data and geomorphic observations the qtf is a 50 km long north south trending set of faults and associated folds that exhibit geomorphic evidence of quaternary surface deformation geomorphic observations and seismic reflection data reveal that these faults dip steeply to the east and merge at depth with a blind west dipping thrust ramp the trend and reverse sense of slip along the qtf indicates that the structure accommodates east west crustal shortening based on uplift of stratigraphic horizons across the fault zone we define a late pliocene to early pleistocene fault slip rate of 0 2 0 3 mm yr and a middle pleistocene to present rate of 0 4 1 2 mm yr on the west dipping thrust ramp this ramp soles to a basal detachment in the triassic section at a depth of 4 5 5 5 km to the west this detachment steps down onto a blind northwest dipping thrust termed the range front thrust a rupture of the qtf in combination with the range front thrust could generate an m w 7 8 earthquake with average displacement of 5 7 m this type of earthquake source poses significant hazards to the adjacent highly populated sichuan basin online material figures detailing cross sections and 3d surfaces additional reflection profiles and dating information

nature of a regional dogleg pattern in maturity profiles from thrace basin northwestern turkey a newly discovered unconformity or a thermal anomaly vitrinite reflectance ro profiles of the thrace basin are characterized by a regional dogleg pattern corresponding to the depths of ceylan and hamitabat formations we investigated the nature of this dogleg pattern using a one dimensional thermal maturity model by simulating three possible geological scenarios 1 two possible newly discovered unconformities one between the hamitabat and soucak or hamitabat and ceylan formations and the other within the hamitabat formation 2 an abnormal paleoheat flow regime paleothermal kick that developed in the oligocene and extended until the end of the early miocene and 3 a sharp thermal conductivity contrast in the stratigraphic column caused by thermally low conductive deposits of the ceylan formation which act as a regional thermal blanket the sensitivity of each suggested scenario within the model and their effect on the observed dogleg pattern have been examined a comparison of the measured and calculated modeled ro profiles from the proposed scenarios shows that the dogleg pattern can be best explained by a combination of the second paleoheat flow and third scenarios thermal conductivity instead of the unconformity scenario however the discovery of these two newly defined discordance surfaces with the help of well and seismic data requires a significant modification to the chronostratigraphy of the thrace basin the hamitabat karaaa ftepe and gaziky formations and the lower sections of the kean formation are suggested to be time correlative counterparts in a newly constructed chronostratigraphy thus the hamitabat formation can be evaluated as a part of the early middle eocene sequence similar to the gaziky formation in this article we suggest that the hamitabat formation be classified as a group instead of a formation

the region of the strandja sill north turkey and the messinian events the two sides of the strandja sill show a highly discontinuous stratigraphic succession since the late oligocene this area together with the sea of marmara basin is usually proposed as the gateway for the paratethyan freshwaters and organisms that constituted the lago mare facies in the mediterranean sea during the messinian salinity crisis msc our investigations involving new field observations and datings together with previous studies suggest that the sill has possibly experienced such a connection at around 8 ma i e significantly before the crisis the proposal of a sea level drop of the black sea before 7 ma is not supported by our data on dinoflagellate cysts consistency of calcareous nannofossil succession at dsdp site 380 is reinforced allowing to reassert that subaerial erosion impacted both the southwestern black sea and the central marmara dardanelles area during the peak of the msc at that time this region was crossed by two oppositely directed fluvial networks further supporting the absence of a marine gateway through the strandja sill it is concluded that none of the lago mare events recorded in the mediterranean during the msc were the consequence of the passage of paratethyan waters and organisms through this area in the black sea the well dated messinian fluvial erosion can be followed offshore the overlying prograding deltaic deposits attest to a fast marine reflooding after the crisis this constitutes a comprehensive erosion sedimentation model in an area intensively explored for hydrocarbons

petroleum geology of the black sea abstract the black sea comprises two extensional basins formed in a back arc setting above the northward subducting tethys ocean close to the southern margin of eurasia the two basins coalesced late in their post rift phases in the pliocene forming the present single depocentre the western black sea was initiated in the aptian when a part of the moesian platform now the western pontides of turkey began to rift and move away to the south east the eastern black sea probably formed by separation of the mid black sea high from the shatsky ridge during the palaeocene to eocene subsequent to rifting the basins were the sites of mainly deep water deposition only during the late miocene was there a major sea level fall leading to the development of a relatively shallow lake most of the margins of the black sea have been extensively modified by late eocene to recent compression associated with closure of the tethys ocean gas chromatography mass spectrometry and carbon isotope analysis of petroleum and rock extracts suggest that most petroleum occurrences around the black sea can be explained by generation from an oil prone source rock of most probably late eocene age although a wider age range is possible in the basin centres burial history modelling and source kitchen mapping indicate that this unit is currently generating both oil and gas in the post rift basin a palaeozoic source rock may have generated gas condensate in the gulf of odessa in bulgarian waters the main plays are associated with the development of an eocene foreland basin kamchia trough and in extensional structures related to western black sea rifting the latter continue into the romanian shelf where there is also potential in rollover anticlines due to gravity sliding of neogene sediments in the gulf of odessa gas condensate has been discovered in several compressional anticlines and there is potential in older extensional structures small gas and oil discoveries around the sea of azov point to further potential offshore around the central azov high in offshore russia and georgia there are large culminations on the shatsky ridge but these are mainly in deep water and may have poor reservoirs there are small compressional structures off the northern turkish coast related to the pontide deformation these may include eocene turbidite reservoirs the extensional fault blocks of the andrusov ridge mid black sea high are seen as having the best potential for large hydrocarbon volumes but in 2200 m of water

viscoelastic coupling model for the earthquake cycle driven from below in a linear system the earthquake cycle can be represented as the sum of a solution which reproduces the earthquake cycle itself viscoelastic coupling model and a solution that provides the driving force we consider two cases one in which the earthquake cycle is driven by stresses transmitted along the schizosphere and a second in which the cycle is driven from below by stresses transmitted along the upper mantle i e the schizosphere and upper mantle respectively act as stress guides in the lithosphere in both cases the driving stress is attributed to steady motion of the stress guide and the upper crust is assumed to be elastic the surface deformation that accumulates during the interseismic interval depends solely upon the earthquake cycle solution viscoelastic coupling model not upon the driving source solution thus geodetic observations of interseismic deformation are insensitive to the source of the driving forces in a linear system in particular the suggestion of bourne et al 1998 that the deformation that accumulates across a transform fault system in the interseismic interval is a replica of the deformation that accumulates in the upper mantle during the same interval does not appear to be correct for linear systems

distribution of active rock uplift along the eastern margin of the tibetan plateau inferences from bedrock channel longitudinal profiles 1 current models of long term river incision into bedrock suggest that the local rate of differential rock uplift should exert a primary control on the gradient of channel longitudinal profiles however discrimination of this effect from the influence of variations in substrate erodibility sediment flux precipitation and transient changes in profile shape has proved difficult in practice here we investigate the controls on the spatial distribution of bedrock channel gradients adjacent to the sichuan basin in an effort to assess the degree and nature of active deformation along this margin of the tibetan plateau analysis of river longitudinal profiles utilizing a channel steepness index a measure of profile gradient normalized for drainage area reveals a zone of anomalously steep channels adjacent to the topographic front of the plateau margin channel profiles are systematically less steep in their headwater reaches on the plateau and in their lower reaches east of the plateau margin comparison of steepness indices to mapped lithologic variations reveals that lithology has only a limited influence on channel gradient in this field area we observe no systematic relationship between steepness indices and upstream drainage area channels of all size are steeper near the plateau margin we argue that these systematic changes are not readily explained as a consequence of increased sediment flux or of orographic precipitation we are led to conclude that steep channel profiles along the topographic front of the plateau reflect active differential rock uplift between this region and the foreland

the 2013 lushan earthquake implications for seismic hazards posed by the range front blind thrust in the sichuan basin china thrust and reverse faults pose significant earthquake hazards in convergent plate margins around the world but have proven difficult to study given the complex nature of their ruptures which often involve multiple along strike and vertically stacked fault segments the 2013 mw 6 6 lushan earthquake exemplified this complexity rupturing a blind thrust fault in the southern longmen shan which border the western sichuan basin in china this event occurred 80 km south of the epicenter of the destructive 2008 mw 7 9 wenchuan earthquake the wenchuan earthquake produced surface ruptures on two parallel fault splays the pengguan and beichuan faults in contrast the lushan earthquake was generated by a ramp in the range front blind thrust rfbt which is in the footwall of the wenchuan rupture we use seismic reflection profiles petroleum wells and relocated seismicity to construct a three dimensional model of this imbricated fault system our model illustrates that the 2013 lushan earthquake ruptured 10 of the rfbt which extends for 250 km along the longmen shan range front and into the western sichuan basin analysis of growth strata in structures above the rfbt fault along strike shows clear evidence of quaternary activity and constrains the middle pleistocene to current slip rate at two locations on the fault single segment and multisegment fault rupture scenarios involving the rfbt suggest the potential for large earthquakes m7 8 that would affect the densely populated western sichuan basin assessing the hazards posed by such complex thrust systems which occur in convergent margins worldwide requires subsurface characterization of fault segments that can be independently associated with geologic and seismologic evidence of fault activity

gas source rock correlation in thrace basin turkey abstract the tertiary thrace basin is the most productive gas province of turkey since exploration in the basin started almost 40 years before many elements of the petroleum system are now known however a gas source rock correlation is still not available as modern methods of correlation have still not been utilized yet a recent study on molecular and isotopic composition of gases could only show that gas accumulations have different origins accordingly a mature source rock with a mixed type of organic matter an early mature source rock with a mainly marine organic matter and a biogenic source have contributed in varying combinations to the formations of gas fields in the basin all of the three potential source rocks namely the lower eocene hamitabat formation upper eocene lower oligocene ceylan formation and the oligocene mezardere formation can fulfill the required maturity and organic matter type requirements in different parts of the basin furthermore the basin wide variation of these parameters is not known due to insufficient subsurface data and non representative distribution of data points therefore a new approach which considers the temporal development of maturation and gas generation in different source rocks within the drainage area of the gas fields and the presence of traps during this critical period was necessary in this study maturation and gas generation history of these three potential source rocks in the drainage areas of gas fields were determined by basin modelling comparing the presence of traps for a given gas field at these critical time periods of maturation and gas generation the most probable source rock could be determined the evaluation of the respective petroleum system in the drainage areas of the gas fields indicated that the hamitabat formation was the source for the pure thermogenic mature gases in the kuzey marmara hamitabat and karacaoglan fields it also contributed to the gas accumulations in several reservoir horizons in the degirmenkoy field the mezardere formation was the source rock for mature thermogenic gas in the karacali hayrabolu and tekirdag fields in these fields mixing with a biogenic gas also took place the mezardere formation was also the source of early mature thermogenic gas in the degirmenkoy field