longriba fault zone in eastern tibet an important tectonic boundary marking the westernmost edge of the yangtze block global positioning system gps measurements across eastern tibet reveal a sharp velocity gradient zone located about 150 km west of the longmen shan frontal thrust zone where eastward block motion of tibet decreases from 12 mm yr to 3 mm yr over a distance of less than 10 km in order to investigate the tectonic cause for this rapid change in gps velocity together with systematic review on the available geological and geophysical data in easternmost tibet we provide new constraints on the tectonic feature of the longriba fault zone from advanced land observing satellite phased array type l band synthetic aperture radar data we propose that the ne striking longriba fault zone is the key structure responsible for the observed sharp gradient in gps velocities in addition the evidence indicates that the longriba fault zone instead of the longmen shan fault zone marks the westernmost edge of the yangtze crustal block given the irregular western margin of the yangtze block the longriba fault zone represents part of the actual tectonic boundary between the songpan ganzi terrane and the yangtze block the newly identified western edge of the yangtze block implies a paleocontinent ocean boundary at depth this boundary was a potential weak zone and may have been exploited during the formation of the longriba fault zone the results of this paper should advance our understanding of the tectonic relationship between the songpan ganzi terrane and yangtze block and provide additional constraints for studies of the geodynamic response of eastern tibet to the ongoing india eurasia collision

impact of riser reconstructions on estimation of secular variation in rates of strike slip faulting revisiting the cherchen river site along the altyn tagh fault nw china abstract slip rates are heavily contested for many of the first order strike slip faults within the indo asian collision zone rates determined geodetically are generally lower than those reported using reconstructions of offset landforms and it is unclear if this discrepancy reflects true secular variation in slip history systematic errors in interpretation or both here i examine the methods used to derive slip rates from reconstructions of displaced fluvial risers and show that such rates are subject to potentially important uncertainties that have largely been overlooked review of published data demonstrates that the slip rate can vary by a factor of 1 2 to 5 for the same site depending on whether the reconstruction uses the age of the upper or lower terrace for the initiation of riser offset to reduce this epistemic uncertainty i have developed six geomorphic indices that can be used to identify the most accurate end member reconstruction 1 comparison of riser offset with inset channel width 2 similarity of riser and tread displacements 3 morphological analysis of the scarp profile 4 riser deflection in plan view 5 diachroneity of terrace abandonment and 6 whether riser crests or bases yield the slip vector without the use of these geomorphic observations the epistemic uncertainty associated with current methods for determining slip rate from offset fluvial risers is likely to be so large that there is no resolvable discrepancy between the gps and geologic rates within the indo asian collision zone application of three of these indices to new field mapping of the cherchen he river site 86 4 e along the central altyn tagh fault yields a revised slip rate of 9 4 2 3 mm yr equivalent within error to the rates previously derived from gps and paleoseismic studies although reinterpretation of published data from the sulamu tagh site 87 4 is consistent with this revised rate additional work is needed to reconcile this result with some of the rates reported near aksay 94 e

joint analysis of the 2014 kangding southwest china earthquake sequence with seismicity relocation and insar inversion over 1000 earthquakes struck the northwest of kangding on the xianshuihe fault in southwest china between 22 and 29 november 2014 including two largest events of mw 5 9 and mw 5 6 the hypocenters of 799 relocated earthquakes suggest that two independent main shock aftershock subsequences occurred on the selaha and zheduotang branches of the xianshuihe fault respectively fault slip inversion results from one interferometric synthetic aperture radar insar interferogram 26 september 2014 to 5 december 2014 show that the mw 5 9 main shock produced a maximum slip of 0 47 m at the depth of 9 km however there is no distinct slip associated with the mw 5 6 main shock the insar determined moment is 2 36 1018 nm with a rigidity of 30 gpa equivalent to mw 6 2 which is about twofold the total seismic moment of all the recorded earthquakes during the insar time span this large discrepancy between geodetic and seismic moment estimates indicates that there was probably rapid aseismic afterslip in the 2 weeks following the mw 5 9 main shock the released seismic energy of this earthquake sequence is far less than the accumulated strain energy since the 1955 m 712 earthquake on the same fault branch which implies that the seismic risk on the selaha kangding segment of the xianshuihe fault remains high

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

timing and style of late pleistocene glaciation in the queer shan northern hengduan mountains in the eastern tibetan plateau glacial landforms and sediments provide evidence for the existence of two late pleistocene major glacial advances in the queer shan northern hengduan mountains in the eastern tibetan plateau in the current study optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during marine isotope stage mis 3 and the last glacial maximum lgm in mis 2 respectively geomorphic evidence shows that the glacial advance during mis 3 was more extensive than that in mis 2 this glacial advance is synchronous with other glaciated areas in the himalaya and tibet but contrasts with global ice volumes that reached their maximum extent during the lgm glaciers in the queer shan are of the summer accumulation type and are mainly fed by precipitation from the south asian monsoon palaeoclimate proxies show that during mis 3 the south asian monsoon strengthened and extended further north into the tibetan plateau to supply more precipitation as snow at high altitudes this in turn led to positive glacier mass balances and caused glaciers to advance however during the lgm despite cooler temperature than in mis 3 the weakened south asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in mis 3 copyright c 2010 john wiley sons ltd glacial landforms and sediments provide evidence for the existence of two late pleistocene major glacial advances in the queer shan northern hengduan mountains in the eastern tibetan plateau in the current study optically stimulated luminescence and electron spin resonance dating results reveal that the two glacial advances occurred during marine isotope stage mis 3 and the last glacial maximum lgm in mis 2 respectively geomorphic evidence shows that the glacial advance during mis 3 was more extensive than that in mis 2 this glacial advance is synchronous with other glaciated areas in the himalaya and tibet but contrasts with global ice volumes that reached their maximum extent during the lgm glaciers in the queer shan are of the summer accumulation type and are mainly fed by precipitation from the south asian monsoon palaeoclimate proxies show that during mis 3 the south asian monsoon strengthened and extended further north into the tibetan plateau to supply more precipitation as snow at high altitudes this in turn led to positive glacier mass balances and caused glaciers to advance however during the lgm despite cooler temperature than in mis 3 the weakened south asian monsoon and the associated reduced precipitation were not as favourable for glacier expansion as in mis 3 copyright c 2010 john wiley sons ltd

historical pattern and behavior of earthquake ruptures along the eastern boundary of the sichuan yunnan faulted block southwestern china abstract the eastern boundary of the sichuan yunnan faulted block in southwestern china which contains four major fault zones named xianshuihe anninghe zemuhe and xiaojiang behaves as a huge left lateral strike slip active fault system where the most frequent seismicity in continental china occurs to uncover the history of earthquake ruptures of this fault system we developed an empirical relation between rupture extent and seismic intensity distribution based on data of those earthquakes whose rupture extents and intensity distributions are well known through analyzing various types of data including distributions of damage or intensity of historical earthquakes as well as surface ruptures and aftershock zones of modern earthquakes we determined systematically the locations and spatial extents of ruptures for 36 main earthquakes and built up a spatial temporal pattern of the rupture history of the fault system for the last several hundred years the spatial temporal rupture pattern contains information of multi cycle and broad scale ruptures from which we find that for most fault segments scales of segment ruptures are time or cycle variable and only in two or three cases do scales of segment ruptures in successive cycles seem to be characteristic in infrequent cases several adjacent and connecting fault units may rupture simultaneously resulting in cascading ruptures triggering of ruptures is common along the fault system but differs in various periods even on a single fault zone triggered ruptures may not occur on fault segments adjacent to a preceding rupture of major earthquake but on other segments at some distance away from the preceding rupture implying that the rupture history determines whether a segment can be triggered or not recurrence intervals of major segment ruptures are longer on the anninghe and zemuhe fault zones and on the southernmost segment of the xiaojiang fault zone than that on the xianshuihe fault zone and the northern and middle segments of the xiaojiang fault zone probably due to the partitioning of slip along major and secondary faults and their complicated fault geometry four seismic gaps along the fault system are recognized where major earthquakes have been absent for a long time

locking depth slip rate and seismicity distribution along the daofu kangding segment of the xianshuihe fault system eastern tibetan plateau abstract in this study 1338 relocated earthquakes ms 1 6 from 1981 to 2018 and 53 gps velocities from 2004 to 2017 were processed to obtain the geometry and kinematic characteristics of the daofu kangding segment of the xianshuihe fault system in southwestern china by analyzing the seismicity depth distribution of the selaha kangding fault we inferred its three branches the yalahe fault selaha fault and zheduotang fault converged into one fault at a depth of approximately 15 km and that a flower shaped structure was observed above this depth furthermore based on a 2d elastic dislocation model the creep rates creep depths slip rates and locking depths of the daofu kangding segment were analyzed in case of the daofu qianning fault the obtained left lateral slip rate was 4 5 1 1 mm a and the locking depth was 5 3 1 9 km because the fault creep rate from a depth of 2 6 km to the surface was 1 3 1 0 mm a the daofu qianning fault cannot generate earthquakes having magnitudes of greater than 7 in the near future however the slip rates were 7 5 1 6 2 3 1 5 and 1 9 1 5 mm a by assuming a locking depth of 15 km for the selaha fault yalahe fault and zheduotang fault respectively furthermore because the creep depth of the selaha fault was 3 4 1 6 km and the creep rate was 7 5 2 8 mm a the accumulated seismic moment since 1725 corresponded to a mw7 1 earthquake

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

micromorphological analysis of coastal sediments from willapa bay washington usa a technique for analysing inferred tsunami deposits tsunami deposits are provisionally distinguished in the field on the basis of anomalous sand horizons fining up and fining landward coupled with organic rich fragmented backwash sediments in this paper micromorphological features of a sediment sequence previously interpreted as being of tsunami origin are described these characteristics are shown to be consistent with the macro scale features used elsewhere but show additional details not seen in standard stratigraphies including possible evidence for individual waves possibly wave magnitude progression organic fragment alignment and intraclast microstructures although replication and more complete studies are needed this analysis confirms the identification of a tsunami in willapa bay in ca 1700 ad while demonstrating a widely applicable technique for confirming or refuting possible tsunami deposits

interseismic slip rate of the northwestern xianshuihe fault from insar data 1 the xianshuihe fault is a highly active strike slip fault system near the eastern margin of the tibetan plateau we use a multi interferogram method to construct a map of line of sight deformation rate due to interseismic strain accumulation on the northwestern xianshuihe fault from a decade of sar data acquired by the ers 1 2 and envisat satellites the rate map shows a clear deformation gradient associated with the fault but slightly offset to the northeast from the surface trace joint inversion of insar rate map and gps data using monte carlo method we estimate a slip rate of 9 12 mm yr with a locking depth of 3 6 km at the 90 confidence level the slip rate agrees with the holocene fault slip rate and the historical earthquakes our results also suggest no significant across fault extension in the future insar data from both ascending and descending orbits may further constrain the 3 d fault slip rate on this fault

a review on active tectonics and deep crustal processes of the western sichuan region eastern margin of the tibetan plateau abstract one of remarkable geological and geomorphological features in continental china is the presence of a north south trending tectonic zone which separates the seismically active tibetan plateau to the west from the tectonically stable south china and ordos blocks to the east the zone also owns a name of north south seismic belt as a large number of great historical earthquakes occur on it the most recent one the 2008 wenchuan earthquake attests its recent tectonic activity in this review i take the western sichuan region as an example to probe the structural styles and kinematic pattern as well as deep geological process associated with tectonic deformation of the north south trending zone through integrated studies on active faults gps crustal deformation and geophysical structure we show that deformation in the western sichuan is governed by interactions among three crustal blocks songpan chuandian and south china of distinctive rheological properties under the tectonic framework that eastward growth of the soft eastern tibet is blocked by the hard lithosphere of the south china block the left lateral xianshuihe fault continues to the north south trending fault system without crustal shortening to form a bounding fault to limit the northern extend of the magnificent clockwise rotation of crustal material around the eastern himalaya syntax upper crust of the three blocks is dominated by brittle deformation whereas the ductile flow of lower crust would drag the brittle upper crustal blocks to move with respect to each other the relative motions among the brittle upper crustal blocks cause strain accumulations among their bounding faults to generate large earthquakes deformation of the western sichuan region can thus be described in terms of combined model of rigid block movement and continuous deformation we suggest this combined model can be applied to entire continental china

three dimensional velocity field of present day crustal motion of the tibetan plateau derived from gps measurements 1 using the measurements of 750 gps stations around the tibetan plateau for over 10 years since 1999 we derived a high resolution 3 d velocity field for the present day crustal movement of the plateau the horizontal velocity field relative to stable eurasia displays in details the crustal movement and tectonic deformation features of the india eurasia continental collision zone with thrust compression lateral extrusion and clockwise rotation the vertical velocity field reveals that the tibetan plateau is continuing to rise as a whole relative to its stable north neighbor however in some subregions uplift is insignificant or even negative the main features of the vertical crustal deformation of the plateau are the following a the himalayan range is still rising at a rate of 2 mm yr the uplift rate is 6 mm yr with respect to the south foot of the himalayan range b the middle eastern plateau has a typical uplift rate between 1 and 2 mm yr and some high mountain ranges in this area like the longmen shan and gongga shan have surprising uplift rates as large as 2 3mm yr c in the middle southern plateau there is a basin and endorheic subregion with a series of ns striking normal faults showing obvious sinking with the rates between 0 and 3 mm yr d the present day rising and sinking subregions generally correspond well to the cenozoic orogenic belts and basins respectively e at the southeastern corner of the plateau there is an apparent trend that the uplift rate is gradually decreasing from between 0 8 and 2 3 mm yr in the inner plateau to between 0 5 and 1 6 mm yr outside the plateau with the decrease of terrain height

quaternary glaciations recorded by glacial and fluvial landforms in the shaluli mountains southeastern tibetan plateau abstract the shaluli mountains a tectonically controlled mountain range between the jinsha and yalong river rifts are located in southeastern tibetan plateau in the central shaluli mountains an ice cap of 3600 km 2 once developed on the haizi shan abundant glacial landforms are present on the haizi shan and in the surrounding river valleys together with the outwash terraces in the yazheku river the northeastern part of the haizi shan provides an ideal site to examine the quaternary glacial history of the region sedimentological and morphostratigraphical analysis field mapping and dating by electron spin resonance esr define at least seven major glacier advances in the haizi shan area six major glacier advances likely occurred during marine oxygen isotope stage mis 16 mis 14 12 mis 6 mis 3 early mis 2 and the global last glacial maximum these can be defined on the basis of esr dating and stratigraphical analysis of the glacial landforms in front of the kuzhaori glacial trough on the southern slope of the haizi shan the outwash terraces in the yazheku river also record four major glacier advances which occurred during mis 16 mis 12 mis 6 and mis 2 in addition the moraines preserved on the southwestern part of the haizi shan suggest that a glacial advance likely occurring during the lateglacial the extent of glaciation on the haizi shan decreased with time

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

deciphering old moraine age distributions in se tibet showing bimodal climatic signal for glaciations marine isotope stages 2 and 6 abstract determining the timing and extent of past glaciations in tibet is essential to reconstruct regional paleoclimate and understand how atmospheric circulation varies due to the high altitude low latitude tibetan plateau in se tibet geomorphological field observation of glacial deposits shows two main imbricated moraines we apply statistical analyses to a compilation of eight new 10be cosmogenic exposure ages from two moraine crests at gmx site and 128 previously published but recalculated exposure ages from 30 additional crests in the region the results show that ages from the sharpest inner moraines range from 14 25 ka corresponding to the full range of marine oxygen isotope stage mis 2 i e last glacial maximum lgm with less than 2 of older outliers the outer moraines have a fundamentally different distribution with scattered ages from 10 to 200 ka obtained using the same method of sampling dating and age modeling proven robust for dating the lgm inner moraines therefore excluding a methodologic artifact this large scatter prevents the application of any statistical analysis to the age distribution at a site with well developed and preserved imbricated moraines cuopu the outer moraine s oldest ages are mis 6 with the oldest one being at the mis 6 mis 7 limit identical to what is observed in the regional compilation following our observations for the lgm moraines where

accuracy of cosmogenic ages for moraines analyses of all published cosmogenic exposure ages for moraine boulders show an average age range of 38 between the oldest and youngest boulders from each moraine this range conflicts with the common assumption that ages of surface boulders are the same as the age of the landform the wide spread in boulder ages is caused by erosion of the moraine surface and consequent exhumation of fresh boulders a diffusion model of surface degradation explains the age range and shows that a randomly sampled small set of boulders n 3 7 will always yield a lower age limit for the moraine the model indicates that for identical dating accuracy six to seven boulders are needed from old and tall moraines 40 000 100 000 yr 50 100 m initial height but only one to four boulders from small moraines 20 000 100 000 yr 10 20 m by following these guidelines the oldest obtained boulder age will be 90 of the moraine age 95 probability this result is only weakly sensitive to a broad range of soil erosion rates our analysis of published boulder ages indicates that 3 of all moraine boulders have prior exposure and 85 of these boulders predate the dated moraine

paleoglaciation of shaluli shan southeastern tibetan plateau reconstructing the paleoglaciation of the tibetan plateau is critical to understanding linkages between regional climate changes and global climate changes and here we focus on the glacial history

southeastward increase of the late quaternary slip rate of the xianshuihe fault eastern tibet geodynamic and seismic hazard implications abstract the left lateral strike slip xianshuihe fault system located in the eastern tibetan plateau is considered as one of the most tectonically active intra continental fault system in china along which more than 20 m 6 5 and more than 10 m 7 earthquakes occurred since 1700 therefore studying its activity especially its slip rate at different time scales is essential to evaluate the regional earthquake hazard here we focus on the central segment of the xianshuihe fault system where the xianshuihe fault near kangding city splays into three branches the selaha yalahe and zheduotang faults in this paper we use precise dating together with precise field measurements of offsets to re estimate the slip rate of the fault that was suggested without precise age constraints we studied three sites where the active selaha fault cuts and left laterally offsets moraine crests and levees we measured horizontal offsets of 96 20 m at tagong levees tg 240 15 m at selaha moraine slh and 80 5 m at yangjiagou moraine yjg using 10be cosmogenic dating we determined abandonment ages at tagong selaha and yangjiagou of 12 5 2 5 2 2 ka 22 2 ka and 18 2 ka respectively by matching the emplacement age of the moraines or levees with their offsets we obtain late quaternary horizontal average slip rates of 7 6 2 3 1 9 mm yr at tg and 10 7 1 3 1 1 mm yr at slh i e 5 7 12 mm yr or between 9 6 and 9 9 mm yr assuming that the slip rate should be constant between the nearby tg and slh sites at yjg we obtain a lower slip rate of 4 4 0 5 mm yr most likely because the parallel zheduotang fault shares the slip rate at this longitude therefore suggesting a 5 mm yr slip rate along the zheduotang fault the 10 mm yr late quaternary rate along the xianshuihe fault is higher than that along the ganzi fault to the nw 6 8 mm yr this appears to be linked to the existence of the longriba fault system that separates the longmenshan and bayan har blocks north of the xianshuihe fault system a higher slip rate along the short 60 km and discontinuous selaha fault compared to that along the long 300 km and linear ganzi fault suggests a high hazard for a m 6 earthquake in the kangding area in the near future which could devastate that densely populated city

incorporating and reporting uncertainties in fault slip rates 1 quantitative slip rate estimates are essential to understanding crustal deformation processes and assessing seismic hazard computing slip rates requires two fundamental ingredients estimates of the age of an offset landforrn or deposit and displacement along the fault of interest because both of these measures contain uncertainty slip rates are inherently uncertain methods to compute and report slip rates have not been standardized and therefore slip rate data are presented inconsistently and are frequently ambiguous in particular slip rate uncertainty is often insufficiently characterized we present a rigorous probabilistic approach to computing and reporting intermediate to long term fault slip rates additionally we have developed freely available software that provides standard age and displacement uncertainty models we demonstrate the method using recent observations from the neodani and death valley fish lake valley fault zones and we compare slip rates determined using this approach with previously published results

too young or too old evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages cosmogenic exposure dating has greatly enhanced our ability to define glacial chronologies spanning several global cold periods and glacial boulder exposure ages are now routinely used to constrai

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

block like versus distributed crustal deformation around the northeastern tibetan plateau abstract it has been debated for decades whether crustal deformation in and around the tibetan plateau is distributed or block like we model crustal deformation in northeastern tibet using a deformable block motion model in which kinematic parameters of block motion and internal deformation and the associated boundary slip rates are inverted for using gps velocity data the f test is used to screen out station velocity outliers justify independence of neighboring blocks and determine the significance of block internal strains through an iteration process as a result fifteen blocks are identified with their boundary faults slipping at rates of 1 10 mm a blocks located east and north of the plateau have large sizes 10 4 km 2 in area in general with little internal deformation six blocks within the plateau in contrast are smaller in sizes with internal strain rates on the order of 1 10 nanostrain a five blocks sitting at the northeast borderland of the plateau have small block sizes but no significant internal deformation our results show sinistral slip rates of 4 3 1 6 and 4 6 1 8 mm a across the western and eastern segments of the haiyuan fault and 10 8 2 3 4 6 2 6 and 3 8 2 1 mm a across the western central and eastern segments of the east kunlun fault respectively the southwestern central and northeastern segments of the longmenshan fault slip right laterally at rates of 1 7 1 1 1 1 0 8 and 1 1 0 8 mm a with shortening rates of 1 1 1 2 0 4 0 8 and 0 8 1 1 mm a respectively we also develop a scheme to convert geodetic strain rate into seismic moment accumulation rate within blocks and at block boundaries and estimate the two rates as 8 40 10 18 and 2 06 10 19 n m a respectively in comparison the corresponding seismic moment release rates are estimated as 6 06 10 18 and 2 44 10 19 n m a using an contemporary earthquake catalog of 1920 2015 such results indicate that the seismic moment accumulation and release rates are comparable for the latest 95 years when the earthquake catalog is complete for strong to large events both geodetic and seismic estimates suggest that a major portion 70 80 of the total seismic moment is accumulated and released at block boundaries and a minor but still significant portion 20 30 is accumulated and released within blocks

glacial advances and stability of the moraine dam on mount namcha barwa since the last glacial maximum eastern himalayan syntaxis abstract the tibetan plateau and indian plain exhibit the largest altitudinal difference between two geographically contiguous areas on earth but the eastern margin of the plateau has not experienced headward erosion of the yarlung zangbo river yzr since 2 5 ma in the past some scientists have argued that moraine dams on mount namcha barwa in the eastern himalayan syntaxis frequently blocked the yzr thus keeping the plateau s margin intact at this point in this study three sets of moraines were identified in the pai valley alongside namcha barwa and were dated using optically stimulated luminescence osl and 10be exposure dating the resultant ages would suggest that three glaciations occurred at 22 2 4 7 and 1 3 ka respectively comparison of osl and 10be ages for glacial advances with local paleoclimatic proxies would suggest that temperature was the dominant factor controlling glacial change because of the paleoglacial advance frequency coupling with rapid fluvial incision moraine dams were cut through by the yzr thus any moraine dams that lost their efficacy in impacting upon knickpoint migration instead similarities between rock uplift and fluvial incision rather than moraine dams might have been the main control impeding headward erosion of the yzr thereby keeping this part of the eastern tibetan plateau margin intact

cooling history of the gongga batholith implications for the xianshuihe fault and miocene kinematics of se tibet abstract using thermochronological data and thermokinematic modeling we constrain the timing of late miocene exhumation of the northern portion of the gongga batholith located in southeast tibet along the xianshuihe fault xf we show that rapid exhumation started in the north of the gongga batholith at 9 ma at a rate of 1 85 km myr and slowed down since 4 ma a magmatic pulse occurring during the early pliocene 4 ma has overprinted the rapid miocene exhumation phase in some parts of the batholith which record mainly early pliocene post magmatic cooling slow exhumation since 4 ma is consistent with the present day lower relief observed in the centre of the batholith which contrasts with the rugged high peaks located to the south we propose that the northern segment of the xf the yalahe fault which is not active at present was active between 9 and 4 ma forming a restraining bend that focused exhumation south of it since 4 ma the selaha and the zheduotang faults form the present day restraining bend south of which the highest part of the massif is located including the gongga shan that rises more than 3000 m above the mean elevation of the plateau in the north of the batholith similar peaks have been removed since the miocene by local relief reduction at high elevations considering that the onset of motion along the xf is contemporaneous with the onset of rapid exhumation recorded along the kangding transect at 9 ma and a total offset of 62 km documented for the xf the average slip rate of the xf is 7 mm yr since 9 ma

new constraints on the late quaternary landscape evolution of the eastern tibetan plateau from 10be and 26al in situ cosmogenic nuclides abstract based on terrestrial cosmogenic nuclide tcn constraints from depth profiles of one granitic regolith from wumingshan and five fluvial terraces from xianshuihe and zagunao rivers we discuss the timing of the last deglaciation the landscape scale denudation and fluvial incision rates across the eastern tibetan plateau in relation to previous work we present a three dimensional graph visualization approach and corresponding constraints to better assess the feasibility and applicability of cosmogenic nuclides depth profile dating the exposure age older than 19 4 ka of the wumingshan regolith corresponds to the retreat of the palaeo daocheng ice cap which covered the yidun terrane during the last glacial maximum lgm most basin wide denudation rate data in the eastern tibetan plateau are lower than 130 mm ka 47 n 90 which is consistent with the wumingshan regolith denudation rate lower than 52 8 mm ka and thus indicate that the landscape scale denudation has been stabilized after the last deglaciation considering the reduction of integrated bulk density due to the accumulation of lower density loess we estimate mean exposure ages of xianshuihe and zagunao river terraces of 4 0 0 7 ka 5 9 0 3 ka 13 4 2 0 ka and 16 6 1 4 ka the observed increase in incision rate from 0 39 mm yr over long timescale 600 ka to 5 88 mm yr over the last 15 ka at the xianshuihe river site is probably due to the transition from glacial to interglacial climatic conditions the fewer abandoned terraces along the zagunao river after the heinrich event 1 h1 indicates that the climate change during the latest glacial interglacial transition impacted less the landscape evolution in a relatively lower elevation area comparison with previously reported fluvial incision rates elsewhere across the eastern margin of the tibetan plateau indicates that incision rates are mainly influenced by abrupt climate change or intensified summer monsoon since the early holocene but probably controlled by regional tectonic uplift or fluvial headward retreat as the timescale increases overall we propose a synthetic pattern of landscape evolution mainly dominated by long term tectonic uplift together with fluvial headward erosion episodically influenced by climatic change throughout the late quaternary

holocene paleoearthquakes of the maoergai fault eastern tibet abstract much work about fault activity and seismic hazard assessment has been conducted on major boundary faults of eastern tibet whereas seismic activity on faults between subblocks is poorly understood the maoergai fault 200 km northwest of and parallel to the longmen shan is the eastern branch of the longriba fault zone that divides the bayan har block into the aba and longmen shan subblocks field investigation indicates that the maoergai fault is a purely right lateral strike slip fault active in the late quaternary our trenches combined with radiocarbon dating and bayesian analysis show that three holocene paleoearthquakes ruptured the maoergai fault at 8510 420 7100 70 and 5170 80 cal yr bp respectively this suggests that the fault fits a cluster model with an average recurrence interval of 1700 years and has a high potential of large earthquakes mw 7 2 7 4 in the near future our results also indicate that an apparent fault scarp on a sloping tread provides an alternative site for paleoseismic studies to determine coseismic horizontal displacement on a strike slip fault and using the age of the upper terrace to determine strike slip rate by displaced terrace riser is probably closer to the true value in streams with insufficient capacities of lateral erosion this study provides useful information for the earthquake risk and fault behavior in eastern tibet

quaternary activity of the zhuozishan west piedmont fault provides insight into the structural development of the wuhai basin and northwestern ordos block china abstract the wuhai basin is located in the northwestern corner of the ordos block analyzing the geometry along with the kinematic and dynamic characteristics of the boundary fault the zhuozishan west piedmont fault zwpf will elucidate the regional tectonic environment and guide earthquake prevention and disaster reduction projects six representative sites were selected for topographic measurements from the northern middle and southern parts displacements of the zwpf were calculated by measuring the top surface elevation of a widely distributed lacustrine layer in the footwall from outcrops at each site and from boreholes in the hanging wall the vertical slip rate of the zwpf was then calculated based on the displacement and age of the lacustrine layer three to four normal fault controlled terraces have developed on the footwall of the zwpf and the top surface of the lacustrine layer is at 1092 1132 m elevation data from boreholes showed that the top surface of the lacustrine layer is at an elevation of 1042 1063 m in the hanging wall vertical slip rates since 70 ka were estimated as 0 5 0 2 to 1 0 0 2 mm a the highest rate of vertical slip was observed at fenghuang ridge in the central part of the fault system and decreased to the south in the northern wuhai basin normal faulting still controls the piedmont landscape however nw se trending reverse faults and secondary folding have resulted from dextral strike slip movement of the fault the wuhai basin developed as a dextral tensional negative flower structure this study indicates that stress conditions of the northwestern margin of the ordos block include ne sw compression and nw se extension and an s shaped rift zone has dominated the scale structure and evolution of the yinchuan wuhai and hetao basins along with the active mode of faulting in these basins

late glacial ice advances in southeast tibet abstract the sensitivity of tibetan glacial systems to north atlantic climate forcing is a major issue in palaeoclimatology in this study we present surface exposure ages of erratic boulders from a valley system in the hengduan mountains southeastern tibet showing evidence of an ice advance during heinrich event 1 cosmogenic nuclide analyses 10 be and 21 ne revealed consistent exposure ages indicating no major periods of burial or pre exposure erosion corrected 3 mm ka 10 be exposure ages range from 13 4 to 16 3 ka this is in agreement with recalculated exposure ages from the same valley system by tschudi s schafer j m zhao z wu x ivy ochs s kubik p w schluchter c 2003 glacial advances in tibet during the younger dryas evidence from cosmogenic 10 be 26 al and 21 ne journal of asian earth sciences 22 301 306 thus this indicates that local glaciers advanced in the investigated area as a response to heinrich event 1 cooling and that periglacial surface adjustments during the younger dryas overprinted the glacial morphology leading to deceptively young exposure ages of certain erratic boulders

an integrated analysis of source parameters seismogenic structure and seismic hazards related to the 2014 ms 6 3 kangding earthquake china abstract on 22 november 2014 an ms 6 3 earthquake occurred in kangding county china focal mechanism solution shows that the two nodal planes were 235 82 173 and 144 83 8 and the focal depth was 9 km seismic slip of the kangding earthquake was bilateral with about 0 5 m maximum slip the rupture zone was confined to depths ranging from 5 to 15 km and laterally extended along the slip and strike directions by about 10 and 12 km respectively most of the seismic moment was released in the first 5 s of the rupture resulting in an earthquake magnitude of mw 6 01 in contrast a slip model obtained by interferometric synthetic aperture radar insar data indicates that the rupture zone was longer than that determined from the seismic data and the earthquake magnitude should be about mw 6 2 although accounting for the contribution of the ms 5 8 aftershock and the other small aftershocks that occurred during the insar observations period the total moment estimated based on the seismic slip model was significantly smaller than that obtained from the insar data based on our analysis we found that the inconsistency between the results determined from the seismic data and the insar data may be caused by the decrease in the shear modulus at shallow depths the noise in the insar data and the occurrence of some afterslips in the northwest region of the fault zone the seismic slip of this earthquake was too small to release the accumulated energy within the entire xianshuihe fault we also found that the coulomb stress in the northwest zone of the kangding daofu seismic gap increased as a result of the historical 2008 ms 8 0 wenchuan and the 2014 ms 6 3 kangding earthquakes suggesting that this area is expected to be a high seismic hazard region for the future

co seismic surface ruptures in qiangtang terrane insight into late cenozoic deformation of central tibet abstract recently large earthquakes mostly occurred at the plateau margins along major lithospheric faults however a co seismic rupture has been discovered in central tibet along the burgar co fault bgcf a 150 km long northwest trending right lateral strike slip fault within the hinterland of the qiangtang terrane central tibet the activity of the bgcf is marked by a 50 km long fresh surface rupture from 83 38 57 e 33 58 54 n to 84 09 50 e 33 47 42 n restrained by a bend with a 17 counter clockwise angle geomorphic offsets measured in the field and from high resolution satellite images indicate the lateral displacements cluster at 1 4 0 1 m 2 7 0 4 m 5 4 0 6 m 9 2 0 8 m and 12 5 1 m the smallest value average 1 4 0 1 m maximum 1 8 m is defined as the most recent co seismic offset of a magnitude mw 7 earthquake other clusters are interpreted as the cumulative events which demonstrate that earthquakes frequently took place along the bgcf the seismic behavior of the bgcf together with widespread sinuous north trending grabens and ne nw strike slip faults around western and central qiangtang indicates that the most recent active structures have deformed scattered in the internal part of this terrane additionally the conjugate strike slip fault systems along the bangong nujiang suture define an intangible southern boundary altogether implying that the qiangtang terrane has undergone significant deformation thus can no longer be treated as an integral block finally compared with the continental slip in eastern qiangtang an alternative geodynamic model for qiangtang is inferred a weak channel flow decoupling the upper and middle lower crust which facilitates the southeastwards extrusion as an entire block in the east and continuous deformation as scattered small crustal wedges without expansive upper and middle lower crust decoupling underground in the western and central areas the qiangtang terrane serves as the dominant place for extensive material to migrate eastward accommodating simultaneous e w extension and n s compression

timing of glacier fluctuations and trigger mechanisms in eastern qinghai tibetan plateau during the late quaternary abstract it is highly debated whether glacial advances on the qinghai tibetan plateau qtp occurred as a response to temperature cooling or whether they were forced by an increase in moisture brought by the intensive indian summer monsoon we here report a case study investigating this issue multiple moraine series in the yingpu valley queer shan ranges of the hengduan mountains and eastern qtp provide an excellent archive for examining the timing and trigger mechanism of glacier fluctuations twenty seven optically stimulated luminescence osl samples of glacial sediments were collected from this valley the quartz osl ages show that the moraine series of y 1 i m and o were formed during the late holocene late glacial the global last glacial maximum lgm and marine oxygen isotope stage mis 3 likely mid mis 3 the youngest y 2 moraines probably formed during the little ice age lia the oldest h moraines formed before mis 3 we found that glacial advances during the late quaternary at the yingpu valley responded to cold stages or cold events rather than episodes of enhanced summer monsoon and moisture as a result glaciers in the monsoonal hengduan mountains were mainly triggered by changes in temperature millennial time scale temperature oscillations might have caused the multiple glacial advances

the jinhe qinghe fault an inactive branch of the xianshuihe xiaojiang fault zone eastern tibet abstract the xianshuihe xiaojiang fault zone xfz forms a prominent linear nw se trending tectonic feature along the southeastern margin of the tibetan plateau the spatial and temporal evolution of the predominantly strike slip movement along the fault remains unclear as estimates for the initiation age of its different segments range from 5 to 13 ma the jinhe qinghe fault jqf the south part of the longmen shan thrust belt provides a key for understanding the tectonic role and deformation history of the xianshuihe xiaojiang fault zone in terms of timing magnitude of displacement and spatial temporal evolution this paper presents research on the structure and chronology of the jqf the results of a geometric and kinematic study of the jinhe qinghe fault show it to be a thrust fault with a left lateral strike slip component the strike slip offset extends at least 13 18 km to southwest based on the shortening of its folds and faulting and based on stream deflection ten apatite fission track apparent ages show a pronounced change in age elevation gradient at 17 2 ma consistent with an abrupt increase of exhumation due to uplift of the hanging wall of the jqf at that time combined with the age of deformed tertiary strata in the footwall of the jqf and the geometric relationships of the jqf with the chenghai fault and the xfz this indicates that the jqf was active between 17 and 5 ma based on the fault chronology geometry and movement we suggest that the fault was a transpressional structure at the south end of the xfz during the period from 17 to 5 ma

field study of a highly active fault zone the xianshuihe fault of southwestern china the xianshuihe fault of western sichuan province china is one of the world s most active faults having produced 4 earthquakes during this century of magnitude 7 along a 350 km length of the fault at least 8 such events have occurred since 1725 in the more limited 150 km long segment including luhuo and daofu major earthquakes in 1904 1923 1973 and 1981 m 7 7 7 6 6 9 were associated with overlapping surficial fault ruptures and with individual left lateral displacements as large as 3 6 m field studies indicate that this high degree of activity is typical of the fault s longer term history the holocene left lateral slip rate on the north western segment of the fault has been 15 5 mm yr decreasing to about 5 mm yr on its southeastern segment based on radiometrically dated offset stream channel and terrace deposits and on offset glacial moraines physiographic features of active faulting are fully as diagrammatic as those of california s san andreas fault mainly because of high altitude preservation and the absence of cultural modification on this eastern margin of the tibetan plateau detailed en echelon tensional and pushup features resulting from surface ruptures in 1973 1955 1923 and 1893 can still be recognized today and new data have been collected bearing on the offsets and fault rupture lengths during these and other events the locations and magnitudes of historic earthquakes suggest that the characteristic earthquake model may apply to the xianshuihe fault obvious geometric segmentation of the fault has controlled the initiation and termination of ruptures in some events whereas segmentation control for others remains obscure based on the historic record repeat times estimated from slip rates and current seismic gaps two segments are particularly likely sites for m 7 earthquakes in the near future the 65 km long segment between daofu and qianning and the 135 km long segment bracketing kangding continuing creep has been documented along some segments of the fault and this together with the high degree of activity and other unique attributes makes the xianshuihe fault one of the most promising sites in the world for earthquake prediction and hazard evaluation studies

miocene emplacement and deformation of the konga shan granite xianshui he fault zone west sichuan china geodynamic implications the presently active sinistral xianshui he strike slip fault xsh is a lithospheric scale strike slip fault in the eastern himalaya in the study area this fault affects the eastern edge of the konga shan granitic massif where it has caused both brittle and ductile deformation a rbsr isochron and nd and pb isotope study of three samples and a upb zircon study of a single sample were completed on the granite upb data indicate a granite emplacement age of 12 8 1 4 ma the rbsr isochrons show that the granite emplacement and the deformational event were synchronous at around 12 10 ma minimum age for deformation the nd and pb isotope compositions of whole rocks and k feldspars indicate the involvement of proterozoic continental crust which is confirmed by upb systematics indicating inherited zircons sinistral faulting along the xsh began at the latest at 12 ma and marks the extrusion toward the east of the west sichuan and south china blocks following their extrusion along the red river fault zone between 50 and 21 ma

constraints on the late quaternary glaciations in tibet from cosmogenic exposure ages of moraine surfaces abstract this contribution provides new constraints on the timing of tibetan glacial recessions recorded by the abandonment of moraines we present cosmogenic radionuclide 10 be inventories at 17 sites in southern and western tibet 32 crests 249 samples and infer the range of permissible emplacement ages based on these analyses individual large embedded rock and boulder samples were collected from the crests of moraine surfaces and analyzed for 10 be abundance we consider two scenarios to interpret the age of glacial recession leading to the moraine surface formation from these sample exposure ages 1 erosion of the moraine surface is insignificant and so the emplacement age of the moraines is reflected by the mean sample age and 2 erosion progressively exposes large boulders with little prior exposure and so the oldest sample age records the minimum moraine emplacement age we found that depending on the scenario chosen the moraine emplacement age can vary by 50 for 100 ka old samples we consider two scaling models for estimating the production rates of 10 be in tibet which has an important although lesser effect on inferred moraine ages while the data presented herein effectively increase the database of sample exposure ages from tibet by 20 we find that uncertainties related to the interpretation of the 10 be abundance within individual samples in terms of moraine emplacement ages are sufficient to accommodate either a view in which glacial advances are associated with temperature minima or precipitation maxima that are recorded by independent paleoclimate proxies a reanalysis of published data from moraines throughout tibet shows that the variation we observe is not unique to our dataset but rather is a robust feature of the tibetan moraine age database thus when viewed in a similar way with other samples collected from this area uncertainties within moraine exposure ages obscure attribution of tibetan glacial advances to temperature minima or precipitation maxima our work suggests that more reliable chronologies of tibetan glaciations will come from improvements in production rate models for this portion of the world as well as a better understanding of the processes that form and modify these geomorphic surfaces

geodetic imaging of potential seismogenic asperities on the xianshuihe anninghe zemuhe fault system southwest china with a new 3 d viscoelastic interseismic coupling model we use gps and interferometric synthetic aperture radar insar measurements to image the spatial variation of interseismic coupling on the xianshuihe anninghe zemuhe xaz fault system a new 3 d viscoelastic interseismic deformation model is developed to infer the rotation and strain rates of blocks postseismic viscoelastic relaxation and interseismic slip deficit on the fault surface discretized with triangular dislocation patches the inversions of synthetic data show that the optimal weight ratio and smoothing factor are both 1 the successive joint inversions of geodetic data with different viscosities reveal six potential fully coupled asperities on the xaz fault system among them the potential asperity between shimian and mianning which does not exist in the case of 1019 pa s is confirmed by the published microearthquake depth profile besides there is another potential partially coupled asperity between daofu and kangding with a length scale up to 140 km all these asperity sizes are larger than the minimum resolvable wavelength the minimum and maximum slip deficit rates near the moxi town are 7 0 and 12 7 mm yr respectively different viscosities have little influence on the roughness of the slip deficit rate distribution and the fitting residuals which probably suggests that our observations cannot provide a good constraint on the viscosity of the middle lower crust the calculation of seismic moment accumulation on each segment indicates that the songlinkou selaha s4 shimian mianning s7 and mianning xichang s8 segments are very close to the rupture of characteristic earthquakes however the confidence level is confined by sparse near fault observations

coulomb stress evolution over the past 200 years and seismic hazard along the xianshuihe fault zone of sichuan china abstract this study focuses on the m 6 7 earthquakes that have occurred since 1816 on the xianshuihe fault zone in southwest china the interseismic coulomb stress accumulation and the coulomb stress changes caused by coseismic dislocation and postseismic viscoelastic relaxation of the previous shocks were computed for different periods on the relevant fault segments based on these results we analyzed the relationship between time adjacent strong shocks and the coulomb stress evolution before every earthquake the analysis suggests that strong earthquakes mostly occurred in the coulomb stress enhancement region caused by coseismic dislocation and postseismic viscoelastic relaxation of the last earthquake considering the coulomb stress evolution at the fault planes of the epicentral area before earthquakes we found that the coulomb stress accumulation caused by the interseismic tectonic loading was dominant for most strong earthquakes for some other earthquakes the stress changes caused by coseismic dislocation and postseismic viscoelastic relaxation of surrounding earthquakes were very significant which may be equivalent to the effect of interseismic tectonic loading lasting hundreds of years based on the time dependent probabilistic risk model and the dieterich 1994 model we estimate the background seismic activity and the future earthquake probability for different fault segments using long term seismic activity and strong earthquake recurrence cycles it is shown that the bamei selaha and kangding segments of the xianshuihe fault zone have high earthquake probability and are likely to have strong earthquakes if energy is accumulated up to the year 2050 the magnitude of an event on these three segments could reach m w 7 2 m w 7 0 and m w 7 1 respectively while if the s7 and s8 cascades rupture the event on these segments could reach a magnitude of up to m w 7 2

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

glacial inception and quaternary mountain glaciations in fennoscandia abstract the aim of this review is twofold first the role of the fennoscandian mountains as a nucleation center for glacial inception is investigated the second objective is to review glacial erosion by mountain glaciers throughout the quaternary all available field data and several modelling experiments show that the fennoscandian mountains seeded the last glaciation since the mountains seem to be of key importance for ice sheet inception it is reasonable to assume a similar inception pattern throughout most of the major pleistocene glaciations this pattern also implies prolonged periods of glacial ice in the fennoscandian mountains during late cenozoic time mountain based glaciers thus have had a long time to act on their substratum resulting in a profound geomorphological impact

denudation pattern across the longriba fault system and implications for the geomorphological evolution of the eastern tibetan margin following the 2008 wenchuan earthquake sichuan china the dextral strike slip longriba fault system lfs has been recognized as a main intracontinental structural boundary within the eastern tibetan plateau while numerous studies have focused on the longmen shan frontal range to constrain the dynamics of the eastern tibetan margin little is known on the lfs particularly on its eventual influence on the geomorphological evolution of the latter here we provide a new data set of denudation rates derived from beryllium 10 concentrations in river sediments from 33 medium sized catchments our sampling area covers the frontier between the dissected margin and the low relief interior plateau our results reveal a sharp increase of denudation across the lfs from 0 1 mm y in the ruoergai basin to 0 3 mm y toward the longmen shan range such denudation pattern indicates a major morphotectonic control of the fault system on the eastern tibetan margin evolution additional topographic analysis confirms the role of the lfs as an important geomorphological boundary restraining the westward propagation of river incision into the low relief areas thus partly preventing the dismantling of the eastern tibetan plateau

surface dating of dynamic landforms young boulders on aging moraines the dating of landforms is crucial to understanding the evolution history and stability of landscapes cosmogenic isotope analysis has recently been used to determine quantitative exposure ages for previously undatable landform surfaces a pioneering application of this technique to date moraines illustrated its considerable potential but suggested a chronology partially inconsistent with existing geological data consideration of the dynamic nature of landforms and of the ever present processes of erosion deposition and weathering leads to a resolution of this inconsistency and more generally offers guidance for realistic interpretation of exposure ages

late cenozoic to holocene deformation in southwestern sichuan and adjacent yunnan china and its role in formation of the southeastern part of the tibetan plateau from at least 2 4 ma to present crust in the southeastern part of the tibetan plateau west of the convex east xianshuihe xiaojiang fault system has deformed internally and rotated clockwise around the eastern himalayan syntaxis the northwest striking ganzi fault zone bounds the rotating crust on the north and has a total left slip of 78 100 km of which 60 km is transferred to the xianshuihe fault zone across a diffuse transfer zone and 22 40 km is absorbed by bending of older structures and crustal shortening crustal shortening is expressed along and east of the eastern end of the ganzi fault zone by mountains capped by permanent glaciers locally rising nearly 1000 m above the average elevation of the tibetan plateau a similar transfer of left slip into shortening occurs farther south across the xianshuihe fault in the high mountains around and east of gongga shan 7556 m the northwest striking convex east left lateral litang fault zone lies southwest of the ganzi xianshuihe xiaojiang fault zone and appears to be less well developed but otherwise similar to the ganzi fault zone the batang chenzhi and other northeast striking right lateral faults of small displacement occur within the rotating crustal fragment together with the left slip faults they accommodate east west shortening northeast of the eastern himalayan syntaxis south of this region of shortening the crust is extending to form grabens within the dali and southern xiaojiang fault systems and in the tengchong volcanic province the progressive change from shortening southward into extension is related to variations in strain that characterize the region from northeast to southeast of the eastern himalayan syntaxis the assemblage of structures in southwestern sichuan geometrically resembles structures of eocene to miocene age in southern yunnan that were positioned northeast of the eastern himalayan syntaxis similar to present day southwestern sichuan at the time of their development the similarity in the structural development in the two areas indicates that crust northeast of the syntaxis underwent a common evolution as the syntaxis migrated northward during the past 50 m y structures in sichuan are less fully developed than older structures in southwestern yunnan and can serve as a guide to reconstruct the progressive tectonic development in the region of the syntaxis deformation in these areas indicates that plateau formation has been complex inhomogeneous and diachronous at scales from 1000 km to less than 100 km

the impact of river capture on the landscape development of the dadu river drainage basin eastern tibetan plateau abstract continental collision between india and eurasia plates and associated compression result in the formation of the tibetan plateau with a mean elevation of 5000 m however how the plateau was formed is still under debate in this study by analyzing multiple topographic metrics in the dadu river drainage basin eastern tibetan plateau together with previous studies we attempt to unravel the landscape development there our results reveal significant differences in the obtained topographic metrics within the dadu river drainage basin higher values of hypsometric integral hi normalized stream length gradient slk topographic relief slope and channel steepness in the middle section of the drainage basin between 29 2 n and 31 n and lower values in the upper north of 31 n and lower sections south of 29 2 n meanwhile these topographic metrics show a good match with the millennial scale erosion rates but the long term exhumation rates contrast between the upper dadu and the lower dadu despite similar topographic metric values we infer that the topographic patterns in the dadu river drainage basin are related to river capture between the dadu and anning rivers which resulted in the adjustment of the landscape in the middle section of the dadu river drainage basin with additional incision occurred but not enough to be recorded by low temperature thermochronometric ages

the limited influence of glaciations in tibet on global climate over the past 170 000 yr extensive ice cover on the tibetan plateau would significantly influence earth s climate in general and the asian monsoon system in particular but extent and timing of quaternary glaciations in tibet remain highly controversial we dated erratics on top of moraines in the climatic key areas of central and east tibet using cosmogenic 10be 26al and 21ne consistent exposure ages obtained by various nuclides indicate a continuous period of exposure since the deposition of the samples our data imply that glacial advances were restricted to a few 10 km during the last 170 kyr in central tibet and during the peak of the last glaciation 24 13 kyr ago in eastern tibet advances of tibetan glaciers were much less prominent than elsewhere in the northern hemisphere most likely due to very arid conditions and high sublimation rates a proposed ice dome covering the entire plateau can be excluded thus albedo increase of tibet most likely did trigger neither northern hemisphere ice ages nor paleomonsoon changes during the last two glacial cycles the glacial advance during marine isotope stage 2 in east tibet and the absence of significant glacial events during the holocene suggest a relation of snowline lowering in east tibet to north atlantic cooling events rather than to periods of high precipitation by an intensified monsoon