aftsolve a program for multi kinetic modeling of apatite fission track data aftsolve is a computer program for deriving thermal history information from apatite fission track data it implements a new fission track annealing model that takes into account the known kinetic variability among different apatite species to fully utilize this model a fission track worker must obtain data that can be used to infer the kinetic characteristics of each apatite grain from which a measurement was taken such data can consist of etch figure lengths or chemical composition the benefit of this overall approach is that it allows useful information to be derived from previously unusable analyses extends the practical range of geological temperatures constrained by fission track analyses and increases overall confidence in model predictions aftsolve also incorporates the effects of fission track orientation relative to the apatite crystallographic c axis variation in initial track length and the biasing effect of 2 5 2 cf irradiation for enhancing confined horizontal track length detection aftsolve is written for windows operating systems and has a graphical interface that allows interactive input of thermal histories and real time generation of estimates for fission track length distributions and ages for up to six simultaneously modeled kinetic populations it also includes procedures for estimating the range of time temperature histories that are statistically consistent with a data set and constraints entered by the user

a noncognate relationship between megacrysts and host basalts from the tuoyun basin chinese tian shan abstract abundant kaersutite and alkali feldspar megacrysts occur together with mantle derived and lower crustal xenoliths including kaersutite hornblendite and syenite in the early cretaceous alkaline basalts of the tuoyun basin in the westernmost chinese tian shan particularly several kaersutite hornblendite cumulate xenoliths have the assemblage of kaersutite alkali feldspar titanian mica titanomagnetite clinopyroxene in which kaersutite occurs as an early stage cumulus phase crystallized from a parental magma and alkali feldspar occurs as a late stage intercumulus phase from the evolved magma between accumulating kaersutite grains the megacrystic and xenolithic kaersutite has much higher mg values 0 70 0 96 than the host basalt 0 47 0 60 the kaersutite and alkali feldspar megacrysts have similar initial ratios 0 7032 0 7033 and 0 7035 0 7038 respectively significantly different from their host basalts 0 7047 0 7054 xenolithic petrography and megacrystic sr isotope geochemis

extension during continental convergence with application to the tibetan plateau the tibetan plateau is the product of crustal thickening caused by the collision between india and asia and is the largest active example of extensional tectonics in a zone of continental collision throughout most of the tertiary the tectonics of the plateau were dominated by north south shortening a significant proportion of which took place on east west striking thrust faults for the last 5 m y or so the plateau has been thinning by the mechanism of extension on north south trending normal faults previous investigations of the collision have been able to account for the large scale features of the tertiary deformation but have failed to explain the transition in the late tertiary to quaternary strain rate field of the plateau from north south compression to east west extension the transition could in principle be effected by a reduction in the rate of convergence between india and asia or by a uniform reduction in strength of the whole continental lithosphere of asia it could not however be effected by a reduction in strength of the elevated region alone this produces increased compressional strain rates in the weakened zone an alternative explanation for the transition to extension comes from considering the thermal evolution of thickened continental lithosphere the lower part of the lithosphere consists of a thermal boundary layer which when thickened by horizontal shortening is colder and denser than its surroundings convective instability of the thickened thermal boundary layer and its replacement by hot asthenosphere would rapidly raise the surface elevation and gravitational potential energy of the overlying part of the lithosphere the convective instability would happen in a time brief compared with the collision time scale 50 m y in the case of india and asia but would only occur after there had already been substantial thickening of the lithosphere numerical experiments show that for a range of lithospheric parameters the increase in surface height as much as 2 km and of potential energy 5 to 10 1012 n m 1 resulting from convective instability of the lower lithosphere are sufficient for east west extension to replace north south compression as the dominant feature of the stress field of the tibetan plateau

rate of slip from multiple quaternary dating methods and paleoseismic investigations along the talas fergana fault tectonic implications for the tien shan range the 400 km long talas fergana fault is one of a series of major right lateral strike slip faults that cross the tien shan range this fault has been recognized as active in the late holocene and accommodates part of the deformation induced by the ongoing indo asian collision the kinematics and the role of this strike slip fault are poorly understood with no large earthquakes reported in the instrumental or historical catalogs and no well constrained geological slip rate estimates here we used high resolution satellite imagery to present a first detailed analysis of the fault segmentation we identified nine geometric segments based on strike variations for the talas fergana fault along the kyldau segment through morphological analyses of an offset alluvial fan and the application of multiple dating methods be 10 al 26 cl 36 luminescence and radiocarbon we calculated a late quaternary slip rate ranging from 2 2 to 6 3 mm year this rate is higher than the geodetic measurements but the discrepancy can be partly explained if the talas fergana fault accommodates shortening by counterclockwise rotation around a vertical axis paleoearthquakes identified by trenching indicate that at least two primary surface ruptures and possibly a third occurred in the past 3 800 years and that no large earthquake has ruptured the kyldau segment since at least 420 years b p possibly within the last 2 700 years making this fault segment a potential candidate to generate an earthquake with m 7 in the near future

late cenozoic tectonic evolution of the northwestern tien shan new age estimates for the initiation of mountain building the tien shan are the quintessential intracontinental range situated more than 1000 km north of the suture between india and asia their initiation and growth in the cenozoic however remain poorly understood in this study we present stratigraphic detrital fission track and magnetostratigraphic results that provide a basis for reconstructing the cenozoic tectonic evolution of the kyrgyz range and adjacent chu basin in the northwestern tien shan detrital fission track thermochronology indicates that the northwestern tien shan was tectonically quiescent for much of the cenozoic prior to uplift and exhumation in the late miocene the kyrgyz range was buried by sediments shed from highlands to the south and or east paired bedrock fission track and u th he ages from a sampling transect of 2 4 km relief demonstrate that rapid exhumation commenced at ca 11 ma initial thrusting in the hinterland was followed by evaporite accumulation 0 4 km m y which coincided with erosion of the pre 11 ma strata that mantled the kyrgyz range between 10 and 3 ma bedrockexhumation rates decreased to 0 3 km m y while sedimentation rates decelerated initially to 0 25 km m y before accelerating to 0 4 km m y at 4 5 ma detrital fission track results indicate that by 4 5 ma

change from late tertiary compression to quaternary extension in southern tibet during the india asia collision field studies in southern tibet show that subsequent to folding resulting from the india asia collision 50 40 ma reverse faults and backthrusts formed as a result of nne ssw and nnw sse trending compressions they affect conglomerates of oligocene miocene age and are probably contemporaneous with shearing on the himalayan main central thrust and folding of paleogene basins along the northern border of southern tibet 25 16 ma rift systems postdate compressional structures they were active during the pleistocene and probably during the pliocene 5 2 ma change from a compressional to an extensional regime in tibet probably occurred during the late miocene 10 5 ma this change is tentatively correlated with uplift inferred by chinese workers from paleogene to present day variations of the tibetan vegetation recent and active faulting in the high plateau results from a wnw ese striking extension this is in agreement with tibetan focal mechanisms the himalayan lowlands are subjected to a nne ssw trending compression as demonstrated by superficial deformations and seismicity therefore the horizontal maximum compressive stress trajectory is roughly parallel to india asia convergence hmax being 1 in the lowlands and 2 in the high plateau this change results from the increase of the vertical principal stress value due to the weight of the elevated mass zz is 3 in the lowlands and 1 in the high plateau thus the third principal stress axis is 2 in the lowlands and 3 in the high plateau allowing extension to occur in the wnw ese direction extensional tectonics are significantly different in southern and northern tibet southern tibet being constrained between the himalayan syntaxes the e w extensional principal deviatoric stress value 3 is of rather small magnitude and the n s trending 2 value is extensional as demonstrated by analysis of recent faults normal components prevail along all the azimuths in the field this favors formation of rift systems of large axial extension on the contrary north of the himalayan syntaxes northern tibet flows easily eastward the e w extensional principal deviatoric stress value 3 is of higher magnitude and the n s stress 2 is compressional as shown by inversion of focal mechanism data this favors strike slip components on faults which deviate from the n s direction as expressed in the field by shorter n s trending graben linked with normal strike slip faults these faults permit some n s shortening in northern tibet without thickening in response to india asia collision in high plateaus which are subjected to lateral compression such as the andean altiplano and tibet the extensional direction is basically controlled by the convergence direction being roughly orthogonal to the latter

kinematic model of active deformation in central asia the velocity field of present day deformation in central asia is modelled using a set of four rotating blocks siberia tarim tibet india on a spherical earth a best fit is inverted on the basis of estimated shortening rates across the main thrust zones himalayas tien shan and measured slip rates along the principal strike slip faults altyn tagh and karakorum separating those blocks the fit to the data implies that nearly all the present convergence between india and asia can be accounted for by slip partitioning on these four zones with as much as 50 absorbed by northeastwards extrusion of tibet this suggests that localised deformation governs the present mechanical behaviour of the central asian lithosphere

active thrusting and folding along the northern tien shan and late cenozoic rotation of the tarim relative to dzungaria and kazakhstan we have studied geometries and rates of late cenozoic thrust faulting and folding along the northern piedmont of the tien shan mountain belt west of urumqi where the m 8 3 manas earthquake occurred on december 23 1906 the northern range of the tien shan rising above 5000 m overthrusts a flexural foredeep filled with up to 11 000 m of sediment of the dzungarian basement our fieldwork reveals that the active thrust reaches the surface 30 km north of the range front within a 200 km long zone of neogene quaternary anticlines fault scarps are clearest across inset terraces within narrow valleys incised through the anticlines by large rivers flowing down from the range in all the valleys the scarps offset vertically the highest terrace surface by the same amount 10 2 0 7 m inferring an early holocene age 10 2 kyr for this terrace which is continuous with the largest recent fans of the piedmont yields a rate of vertical throw of 1 0 0 3mm yr on the main active thrust at the surface a quantitative morphological analysis of the degradation of terrace edges that are offset by the thrust corroborates such a rate and yields a mass diffusivity of 5 5 2 5 m 2 kyr a rather fresh surface scarp 0 8 0 15 m high that is unlikely to result from shallow earthquakes with 6 m 7 in the last 230 years is visible at the extremities of the main fold zone we associate this scarp with the 1906 manas earthquake and infer that a structure comprising a deep basement ramp under the range gently dipping flats in the foreland and shallow ramps responsible for the formation of the active fault propagation anticlines could have been activated by that earthquake if so the return period of a 1906 type event would be 850 380 years the small size of the scarp for an earthquake of this magnitude suggests that a large fraction of the slip at depth 2 3 is taken up by incremental folding near the surface comparable earthquakes might activate flat detachments and ramp anticlines at a distance from the front of other rising quaternary ranges such as the san gabriel mountains in california or the mont blanc aar massifs in the alps we estimate the finite cenozoic shortening of the folded dzungarian sediments to be of the order of 30 km and the cenozoic shortening rate to have been 3 1 5 mm yr assuming comparable shortening along the tarim piedmont and minor additional active thrusting within the mountain belt we infer the rate of shortening across the tien shan to be at least 6 3 mm yr at the longitude of manas 85 5 e a total shortening of 125 30 km is estimated from crustal thickening assuming local airy isostatic equilibrium under the same assumption serial n s sections imply that cenozoic shortening across the belt increases westwards to 203 50 km at the longitude of kashgar 76 e as reflected by the westward increase of the width of the belt this strain gradient implies a clockwise rotation of tarim relative to dzungaria and kazakhstan of 7 2 5 around a pole located near the eastern extremity of the tien shan west of hami 96 e 43 5 n comparable to that revealed by paleomagnetism between tarim and dzungaria 8 6 8 7 a 6 mm yr rate of shortening at the longitude of manas would imply a rate of rotation of 0 45 m y and would be consistent with a shortening rate of 12 mm yr north of kashgar taking such values to be representative of late cenozoic rates would place the onset of reactivation of the tien shan by the india asia collision in the early to middle miocene 16 22 9 m y in accord with the existence of particularly thick late neogene and quaternary deposits such reactivation would thus have started much later than the collision roughly at the time of the great mid miocene changes in tectonic regimes denudation and sedimentation rates observed in southeast asia the himalayas and the bay of bengal and of the correlative rapid change in seawater sr isotopic ratio 20 to 15 ma like these other changes the rise of the tien shan might be a distant consequence of the end of indochina s escape

did the growth of tibetan topography control the locus and evolution of tien shan mountain building the tien shan in central asia are the pre eminent example of intraplate mountain building and are typically considered an indirect result of the india eurasia collision via the northward indentation of the relatively strong precambrian lithosphere of the tarim plate into the relatively weak paleozoic lithosphere of the tien shan region this hypothesis fails to fully explain the concentration of tien shan mountain building along a tibet parallel axis located 500 700 km from tibet and also fails to explain the close synchronization of tien shan mountain building events with mountain building in tibet i suggest that bending stresses from lithospheric flexure in central asia exerted a critical influence on the locus and evolution of the tien shan models of paleogene to middle miocene flexure indicate that the growth of northeast tibet may have superimposed a strong bending stress field on the regional stress field the resultant stress field is characterized by strong topography normal tensile stress in the tarim basin and an 15 increase in compressive stress in the vicinity of the tien shan this stress field severely reduces the likelihood of mountain building south of the tien shan and increases the likelihood of mountain building within the tien shan this result suggests that the generation of bending stresses from lithospheric flexure is a viable and important mechanism for the propagation of stress and hence deformation into continental interiors

relationships between meso cenozoic denudation in the eastern tian shan and uranium mineralization in the turpan hami basin nw china constraints from apatite fission track study abstract the eastern tian shan tectonic belt located in the southern domain of the central asian orogenic belt consists of the bogda mountain range turpan hami tuha basin and choltagh mountain range from north to south understanding the meso cenozoic denudation history of the eastern tian shan is critical to unravel the genesis of sandstone type uranium u mineralization in the tuha basin in this paper thirteen granite and sandstone samples were collected along two north south transects in the west of the eastern tian shan for apatite fission track thermochronological study the apatite fission track ages obtained in this study in combination with the thermal history modeling results and previous thermochronological data indicate three main episodes of denudation in the eastern tian shan since the mesozoic i e late jurassic to early cretaceous 160 135 ma late cretaceous to early eocene 100 50 ma and late eocene to early miocene 35 20 ma the late cretaceous denudation events are related to the kohistan dras arc accretion collision that affects the tian shan mountain range extensively whereas the cenozoic ones are related to the india asia collision regional distribution of apatite fission track ages in the eastern tian shan and comparison with u mineralization ages in the tuha basin suggest that the choltagh mountain range began to denudate in the late jurassic exposing high u bearing volcanic rocks on the surface and resulting in significant u mineralization in the southern part of the tuha basin in the cretaceous whereas the bogda mountain range in the north did not experience significant denudation until the late eocene due to the relatively low exhumation of the bogda mountain range and limited exposure of u bearing rocks u mineralization in the tuha basin is minor during the cenozoic but the newly deposited sediments helped the preservation of the u deposits that were formed in the cretaceous

sensitivity of lacustrine stromatolites to cenozoic tectonic and climatic forcing in the southern junggar basin nw china new insights from mineralogical stable and clumped isotope compositions abstract lacustrine stromatolites serve as high resolution and sensitive archives of palaeoenvironmental settings and palaeoclimatic conditions an exceptionally well developed stromatolite bed was discovered within nearshore shallow lacustrine sediments of the lower miocene taxihe formation on the southern margin of the junggar basin north of the tian shan range we investigated the morphology mineralogy clumped and traditional stable isotope geochemistry of the stromatolites by using a multi method approach with the application of x ray diffraction analysis advanced mineral identification and characterization amicscan a clumped isotope palaeothermometer and modelling the overall positive excursions and covariance of 18o varying from 10 61 to 5 82 v pdb and 13c ranging between 1 27 and 2 08 v pdb values are interpreted as the result of deposition in a closed basin system under local progressive evaporation conditions during an episode of aridification clumped isotope proxy records display a significant decrease in water 18o values and a decline of lake water temperature from 38 to 32 c suggesting a shift towards more arid and relatively cooler conditions during the course of stromatolite accretion this interpretation agrees with lake volume and water level decreases inferred from isotope modelling results the late cenozoic aridification of the southern margin of the junggar basin is thus interpreted from a new and unique perspective to have prevailed since the early miocene driven by renewed uplift of the northern tian shan range the investigated stromatolite records reflect a snapshot of the local palaeoclimatic and palaeoenvironmental evolution and our work provides references for potential studies of future discoveries of lacustrine microbialites in northwestern china

ulster white limestone formation upper cretaceous of northern ireland effects of basalt loading on chalk diagenesis the ulster white limestone formation is an unusual chalk because it underwent a period of post depositional emergence and erosion followed by burial under 1 5 2 0 km of tertiary basalts a high degree of pressure solution and cementation produced a well lithified limestone with low porosities 2 3 10 4 the ulster white limestone shows no evidence of thermally induced textural alteration except for thin 0 5 m pseudospar contact recrystallization zones adjoining basalt dykes whole rock 18o values of samples not associated with basalt dykes range from 3 26 o to 6 50 o pdb the 18o values of macropore cements range from 4 96 o to 11 52 o mean 8 27 o modelling of the diagenesis of the ulster white limestone using trace element concentrations and carbon oxygen and strontium isotopic ratios of whole rock and cement samples suggests a low water rock ratio and either marine or mixed marine meteoric pore water environment during the main episode of recrystallization the maximum possible burial temperature was modelled to be 105 c the diagenetic history of the ulster white limestone is similar to that of north sea chalks that are at comparable burial depths as the ulster white limestone after basalt deposition the geochemical data show no indication of hydrothermal alteration associated with the overlying basalts the degree of alteration of fine grained limestones composed predominantly of low magnesium calcite such as the cretaceous tertiary chalks appears to be controlled largely by the burial effective stress history of the limestone

interference of lithospheric folding in western central asia by simultaneous indian and arabian plate indentation abstract large scale intraplate deformation of the crust and the lithosphere in central asia as a result of the indentation of india has been extensively documented in contrast the impact of continental collision between arabia and eurasia on lithosphere tectonics in front of the main suture zone has received much less attention the resulting neogene shortening and uplift of the external zagros alborz kopeh dagh and caucasus mountain belts in iran and surrounding areas is characterised by a simultaneous onset of major topography growth at ca 5 ma at the same time subsidence accelerated in the adjacent caspian turan and amu darya basins we present evidence for interference of lithospheric folding patterns induced by the arabian and indian collision with eurasia wavelengths and spatial patterns are inferred from satellite derived topography and gravity models the observed interference of the patterns of folding appears to be primarily the result of spatial orientation of the two indenters differences in their convergence velocities and the thermo mechanical structure of the lithosphere west and east of the kugitang tunka line

denudation and cooling of the lake teletskoye region in the altai mountains south siberia as revealed by apatite fission track thermochronology abstract lake teletskoye occupies a narrow graben located in the northwestern sector of the altai fold belt in south siberia the lake basin is thought to have formed during the pleistocene as a distant result of the cenozoic collision of india and eurasia that caused a tectonic reactivation of the palaeozoic gorny altai ga and west sayan ws blocks the present work reports of a pilot fission track study performed on 13 apatite separates collected from rocks that were sampled along two profiles in close proximity of the lake the age length data and aft thermochronological modelling reveal two important phases of cooling in the altai mountains a first one during the late jurassic early cretaceous and a second one that started in the miocene pliocene and that persists until today the first event is interpreted to result from uplift induced denudation probably related to the closure of the mongol okhotsk ocean the second event can be linked to the young cenozoic movements that lie at the origin of the formation of the lake teletskoye basin

cenozoic deformation of the tarim basin and surrounding ranges xinjiang china a regional overview abstract with its central position between the tibetan plateau and the tian shan range the tarim basin is a key element of the cenozoic asian orogenic system however a comprehensive regional study and more particularly the quantification of shortening through this basin and its margins are still needed to understand its role in the cenozoic deformation of asia from a compilation of previous works together with an extensive dataset of satellite field seismic and well data we provide a tectonic map of the cenozoic structures and four balanced geological transects of the tarim basin and its surrounding ranges based on this map and these cross sections we characterize the cenozoic deformation of the original proterozoic tarim block from structural restorations and crustal budgets we also quantify the compressive component of this deformation most of the cenozoic compressive deformation from 94 to 100 is concentrated in the ranges along the block margins to the west up to 78 23 km and 54 24 18 km of crustal shortening are accommodated across the compressive western kunlun and southwestern tian shan ranges while to the east up to 38 6 18 km and 15 20 15 km are accommodated across the transpressive altyn tagh and southeastern tian shan ranges a non negligible amount of compressive deformation up to 6 is also accommodated within the tarim basin by large basement cored uplifts with a vergence synthetic to the deformation of the tibetan plateau edge to the west the bachu uplift absorbs 5 km of the total crustal shortening of the western kunlun thrust system while to the south the tanan uplift accumulates 0 6 km of the altyn tagh strike slip system structural inheritance has a major influence on the cenozoic deformation since 33 3 to 100 of the total shortening is accommodated by reactivated basement structures inherited from the protero paleozoic history of the tarim block finally we argue that the basement cored uplifts in the centre of the basin imply a deformation transfer from the tibetan plateau to the tian shan above a deep crustal decollement decoupling the deforming crust from an underlying rigid mantle

a review of the western part of the altaids a key to understanding the architecture of accretionary orogens abstract the altaids is one of the largest accretionary collages in the world and the tectonic styles of the accretionary processes have been interpreted in several ways including as an amalgamation of multiple terranes as a result of oroclinal bending of a long single arc or as a caledonian continental collision based on recent tectonostratigraphic analyses together with paleomagnetic data the tectonic styles of the neoproterozoic to paleozoic accretionary processes of the altaids are discussed the western altaids is the main focus of the study which was mainly composed of several independent linear components such as arcs and microcontinents with proterozoic basement and cover rocks various kinds of arcs existed in the paleo asian ocean including a complicated type of arc alaskan type which is a combination of the japan and mariana type intra oceanic arcs and the cordillera type continental arcs these linear components rotated and collided with each other with multiple subduction polarities which could have been an important result of multiple linear element amalgamation and which has contributed greatly to the architecture of the eurasian continent the basic tectonic styles of the altaids can be summarized as arc arc collision oroclinal bending and large scale rotation and multiple subductions with a complicated archipelago paleogeography these basic features of accretionary orogens in general can be attributed to the amalgamation of complicated multiple linear elements some mesozoic to cenozoic accretionary orogens in the world are also characterized by processes of multiple linear element amalgamation more attention should be paid to the multiple linear element amalgamation of ancient accretionary orogens which will shed light on lateral and vertical continental growth

a three dimensional moho depth model for the tien shan from egm2008 gravity data 1 the tien shan in central asia is the largest intracontinental mountain range in the world but it is 1500 km away from the collision zone between the indian and eurasian plates this region has been and still is the focus of numerous geoscientific studies mainly because of its evolutionary history and its unique position in the eurasian lithosphere plate so far mainly seismological data have been used to explore the origin of and ongoing seismic activity in this region but only one study has investigated terrestrial gravity data in this study a new gravity data set egm2008 is used to determine the crust mantle boundary mohorovicic discontinuity moho of the tien shan using inversion of gravity data in addition an isostatic moho is calculated from topographic data which by comparison to the results of the gravity inversion illuminates the effects of isostatic compensation the results of the gravity inversion generally agree with results of previous seismic studies and indicate that the tien shan has a mountain root with a thickness of about 75 km furthermore the moho is shallow under the basins e g in the tarim and ili basins the comparison with the isostatic moho indicates an over compensation of the orogen and an under compensation of the basins the over compensation results from the former subduction of the tarim basin terrane in the south the under compensation of the tarim basin is generated by support of the terrane between the tien shan in the north and the pamir mountains tibet and himalayas in the south

early cretaceous denudation related to convergent tectonics in the baikal region se siberia we present 24 new apatite fission track aft ages and 18 track length measurements from the baikal region se siberia most samples have aft ages between 140 and 100 ma with relatively high mean track lengths c 13 2 m the relationship between aft ages elevation and mean track lengths indicate that the samples record rapid cooling during the early cretaceous 140 120 ma as also shown by thermal history inversion of track length distributions cooling took place during a late jurassic early cretaceous orogenic phase related to closure of the mongol okhotsk ocean and reflected in the exhumation of metamorphic core complexes followed by thrusting and reverse faulting basin inversion and large vertical motions the variation in aft ages throughout the study area can be partly explained by differences in geothermal structure but differential denudation also played a role minimum amounts of early cretaceous denudation are estimated at 2 3 km

tectonic history of the kyrgyz south tien shan atbashi inylchek suture zone the role of inherited structures during deformation propagation 1 multimethod chronology was applied on intrusives bordering the kyrgyz south tien shan suture stss to decipher the timing of 1 formation and amalgamation of the suturing units and 2 intracontinental deformation that built the bordering mountain ranges zircon u pb data indicate similarities between the tien shan and tarim precambrian crust caledonian 440 410 ma and hercynian 310 280 ma zircon u pb ages were found at the edge of the stss related to subduction and closure of the turkestan ocean and the formation of the suture itself permian triassic 280 210 ma titanite fission track and zircon u th he data record the first signs of exhumation when the stss evolved into a shear zone and the adjacent tarim basin started to subside low temperature thermochronological apatite fission track zircon and apatite u th he analyses reveal three distinct cooling phases becoming younger toward the stss center 1 jurassic cretaceous cooling ages provide evidence that a mesozoic south tien shan orogen formed as a response to the cimmerian orogeny 2 early paleogene 60 45 ma data indicate a renewed pulse of stss reactivation during the early cenozoic 3 neogene ages constrain the onset of the modern tien shan mountain building to the late oligocene 30 25 ma which intensified during the miocene 10 8 ma and pliocene 3 2 ma the cenozoic signals may reflect renewed responses to collisions at the southern eurasian border i e the kohistan dras and india eurasia collisions this progressive rejuvenation of the stss demonstrates that deformation has not migrated steadily into the forelands but was focused on pre existing basement structures

new structural data on late paleozoic tectonics in the kyrgyz tien shan central asian orogenic belt abstract the tectonic evolution of the central asian orogenic belt caob is characterized by the successive accretion of lithospheric blocks leading to different interpretations about the polarity of subductions during the paleozoic the number of microplates and oceanic basins and the timing of tectonic events this is especially the case in the tien shan area in this paper we propose new structural maps and cross sections of middle and south kyrgyz tien shan mts and sts respectively these cross sections highlight an overall dextral strike slip shear zone in the mts at the crustal scale and a north verging structure in the sts these structures are carboniferous in age and sealed by a late carboniferous conglomerate later overlain by mesozoic and cenozoic deposits the sts exhibits two deformation phases 1 a top to the south normal shearing that can be related to subduction or exhumation dynamics and 2 a top to the north nappe stacking that we link to the late paleozoic collisional events between the mts and the tarim block we propose a new interpretation of the tectonic evolution of the kyrgyz tien shan during the late paleozoic collision this model involves a partitioned collisional deformation in late carboniferous times with an orthogonal collision to the south between the tarim and mts and a strike slip regime to the north along a dextral e w zone located between the mts and the north tien shan kazakh platform the so called nikolaev line the docking of the large tarim craton against the caob corresponds to a collision phase which ended the long lived paleozoic subduction history in the caob and was followed in the ts region by intense strike slip deformation during the permian

late cenozoic slip on the talas ferghana fault the tien shan central asia although cenozoic crustal shortening and thickening by thrust faulting have built the present tien shan active right lateral shear on the northwest trending talas ferghana fault appears to be the most rapid localized deformation in the belt ephemeral stream valleys have been offset right laterally tens of metres new and published radiocarbon dates of organic material deposited in depressions blocked by offset ridges place upper bounds on the average holocene slip rate at 18 localities uncertainties allow 14 upper bounds to overlap the range of 8 16 mm yr and 95 confidence limits on such bounds at 11 sites are entirely within this range we infer that the rate of 10 mm yr is not simply an upper bound but applies to the late holocene epoch although the bounds on rates permit more rapid slip in the northwest than the southeast they do not place a useful constraint on variations in slip rate along the fault offsets of paleozoic facies boundaries imply a total right lateral shear of 180 250 km but early cretaceous sedimentary rock appears to have been offset only 60 10 km published paleomagnetic declinations of cretaceous miocene rock demonstrate 20 30 of counterclockwise rotation of the ferghana valley which lies just west of the talas ferghana fault with respect to stable parts of eurasia and 20 11 with respect to the central tien shan east of the fault these declinations are consistent with a maximum northwestward translation of 70 210 km of the ferghana valley at the talas ferghana fault and therefore with a similar maximum horizontal shortening across the chatkal ranges which lie between the ferghana valley and the kazakh platform estimates of crustal thickness beneath the chatkal ranges however permit only 60 100 km of cenozoic shortening if 100 km of slip on the talas ferghana fault accumulated at a constant rate of 10 mm yr it would imply an initiation of slip more recently than ca 10 ma long after india collided with the rest of eurasia

cenozoic tectonic and geodynamic evolution of the kyrgyz tien shan mountains a review of geological thermochronological and geophysical data abstract the complex crustal structure of the tien shan has a strong impact on the distribution of strain induced by the india eurasia collision with intracontinental deformation in eurasia s interior as a distant effect the northward propagation of the india eurasia deformation front is suggested by the rejuvenation of mountain ranges and intermittent intramontane basins the tien shan basement is formed by the rigid heterogeneous precambrian blocks microcontinents of tarim issyk kul or central tien shan and aktyuz boordin surrounded by a soft matrix of paleozoic accretion collision belts the kyrgyz tien shan mountains are situated between the active structures of the tarim plate and the pamir indenter south and the stable kazakhstan shield north underplating by the tarim plate and thrusting by the pamirs are responsible for the building of the cenozoic tien shan the reactivation of its inherited structural fabric and the tectonic layering of the upper lithosphere underlying the area large earthquakes m 6 delineate the northern and southern margins of the issyk kul microcontinent indicating that crustal heterogeneity influenced the location of active structures in the northern kyrgyz tien shan

kinematics topography shortening and extrusion in the india eurasia collision we examine the problem of partitioning between shortening and extrusion in the india asia collision since 45 ma we compute the amount of shortening expected from the kinematics of india s motion with respect to eurasia using the reconstruction at collision time to put bounds on the possible amounts of surface loss within greater india and within eurasia we then compute the amounts of surface loss corresponding to the thickened crust of tibet and of the himalayas assuming conservation of continental crust the spatial distribution of the topography reveals a large systematic deficit of crustal thickening distributed rather uniformly west of the eastern syntaxis but an excess of shortening east of it this distribution indicates an important eastward crustal mass transfer however the excess mass east of the eastern syntaxis does not account for more than one third to one half of the deficit west of the eastern syntaxis the deficit may be accounted either by loss of lower crust into the mantle for example through massive eclogitization or by lateral extrusion of nonthickened crust a mass budget of the crust of the himalayas indicates that lower crust has not been conserved there but the deficit is so large that local loss in the mantle is unlikely to be the unique cause of the deficit alternatively following zhao and morgan 1985 lower crust may have been transferred below the tibetan crust we conclude that a combination of possible transfer of lower crust to the mantle by eclogitization and lateral extrusion has to account for a minimum of one third and a maximum of one half of the total amount of shortening between india and asia since 45 ma this conclusion leaves open the possibility that the partitioning between extrusion and loss of lower crust into the mantle on the one hand and shortening on the other hand has significantly changed during the 45 m y history of the collision

paleozoic multiple accretionary and collisional processes of the beishan orogenic collage in the paper by xiao and others american journal of science v 310 p 1553 1594 1 please substitute figure 16 reproduced here for figure 16 that appears between pages 1573 and 1574 the original figure 16 2 was printed at an improper size figure 3 1 lookup volpage 310

mesozoic and cenozoic tectonic history of the central chinese tian shan reactivated tectonic structures and active deformation 1 the present day topography of the tian shan range is considered to result from crustal shortening related to the ongoing india asia collision that started in the early tertiary in this study we report evidence for several episodes of localized tectonic activity which occurred prior to that major orogenic event apatite fission track analysis and u th he dating on apatite and zircon indicate that inherited paleozoic structures were reactivated in the late paleozoic early mesozoic during a cimmerian orogenic episode and also in the late cretaceous paleogene around 65 60 ma these reactivations could have resulted from the accretion of the kohistan dras arc or lithospheric extension in the siberia mongolia zone activity resumed in the late mesozoic prior to the major tertiary orogenic phase finally the ongoing deformation which again reactivates inherited tectonic structures tends to propagate inside the endoreic basins that were preserved in the range leading to their progressive closure this study demonstrates the importance of inherited structures in localizing the first increments of the deformation before it propagates into yet undeformed areas

dynamic support of the tien shan lithosphere based on flexural and rheological modeling abstract the tien shan is a high young and seismically active intracontinental mountain belt in central asia that has been uplifted approximately 3 km over the past 10 ma a flexural analysis using bouguer gravity and topographic data was used to determine the dynamic lithospheric mechanisms that are responsible for the topographic uplift and crustal thickening of the range bouguer gravity anomalies were used to constrain flexural models for isostatic compensation associated with the large relief of the tien shan this is explained by significant underthrusting of a continuous elastic plate below the tien shan with an effective elastic thicknesses te that gradually changes from 40 to 50 km in the tarim and junggar basins and the kazakh plate to 20 23 km beneath the tien shan horizontal shortening due to folding and thrusting of the upper middle crust causes uplift and crustal thickening of the margin of the tien shan the regional and local compensation occur at the eastern and western parts of the tien shan respectively rheological modeling using a simple geothermal structure for the tien shan reveals that the base of the strong upper crust of tibet is at a depth of 30 35 km which is consistent with the depths of 7776 earthquakes between 1970 and 2011 which serve as constraints on the brittle failure domain of the area the moho depths are used to determine the thickness of the lower crust 17 25 km and to understand the mobility of the lower crustal flow of the tien shan the tendency for the strong upper crust to flow over the weak ductile lower crust or middle lower crust depends on the thickness of the lower crust in other words its strength depends on the depths of the base of the upper crust and the moho the larger the difference the easier it is for the upper crust to flow relative to the strong upper mantle lithosphere the crustal deformation is decoupled from deformation of the upper mantle lithosphere by the weak ductile lower crust of the tien shan

relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates the tien shan a high seismically active intracontinental mountain belt 1 000 2 000 km north of the himalaya has grown as a result of india s collision with asia1 the crustal shortening 200 50 km refs 2 3 and thickening that gave rise to the tien shan accommodates only a small fraction of india s total penetration into asia 2 000 3 000km and the temporal relationship of deformation in this belt to the india asia collision remains unclear here we report geodetic measurements of the tien shan using the global positioning system gps that indicate that the current crustal shortening rate is nearly half of india s convergence rate with eurasia in this area4 we infer a total shortening rate for the tien shan of 20 mm yr 1 which is approximately twice that inferred previously from the extrapolation of slip rates in the holocene3 and earthquake induced displacements during this century5 suggesting that the rate of mountain building in this region has accelerated several fold since the onset of collision 50 55 myr ago6 7 if as we argue the current shortening rate can be extrapolated to geological timescales then our results suggest that most of the tien shan has been constructed during the past 10 myr perhaps in response to an increased horizontal force following an abrupt rise of the tibetan plateau8 9

identification of preserved fatty acids in archaeological floor sediments from prehistoric sites at ban non wat and nong hua raet in northeast thailand using gas chromatography abstract this paper presents the first record of fatty acids recovered from archaeological sediment samples in southeast asia fatty acid analysis in archaeology provides a good source of evidence for the identification and interpretation of prehistoric dietary patterns by identifying organic remains of animal and plant foods prehistoric hard floor sediment samples excavated from prehistoric sites of ban non wat and nong hua raet located in the upper catchment of the mun river valley in thailand were analysed for this study the samples are from compressed sediment features identified during excavation as floors and interpreted as some form of living or working surfaces dated to the iron age and neolithic periods around 2000 bc ad 500 triglycerides were extracted in hexane derivatized to fatty acid methyl esters and analysed using gas chromatography flame ionization detector and gas chromatography mass spectrometry twenty fatty acids including saturated and unsaturated counterparts were identified in the hard floor sediments comparison with control samples indicate that the floor samples have distinctive fatty acid assemblages interpreted to relate to the anthropogenic activity associated with the formation of the floors results suggest that many of the fatty acids are mainly of degraded animal origin possibly from ruminants including cow and deer

building the northern tien shan integrated thermal structural and topographic constraints abstract paired apatite fission track and u th he dates provide the first late cenozoic cooling ages for the northern tien shan these data clearly argue for pulsed deformation since the late miocene with early 10 11 ma and late 0 3 ma intervals of rapid exhumation separated by an extended interval of much slower rates by integrating these bedrock cooling rates with shortening estimates derived from a balanced section detrital cooling ages and geomorphological estimates of conditions before deformation we reconstruct a four stage history of range growth and exhumation following 100 m yr of tectonic quiescence abruptly accelerated rock uplift exhumation and cooling in the kyrgyz range commenced at 11 ma with rates exceeding 1 km m yr during the subsequent 7 m yr deformation and cooling rates decreased three to sixfold before accelerating by comparable amounts during the past 3 m yr since mid miocene times the surface elevation of the kyrgyz range has increased 2 km consistent with

deep seated gravitational slope deformation dsgsd and slow moving landslides in the southern tien shan mountains new insights from insar tectonic and geomorphic analysis we investigated deep seated gravitational slope deformation dsgsd and slow mass movements in the southern tien shan mountains front using synthetic aperture radar sar time series data obtained by the alos palsar satellite dsgsd evolves with a variety of geomorphological changes e g valley erosion incision of slope drainage networks over time that affect earth surfaces and therefore often remain unexplored we analysed 118 interferograms generated from 20 sar images that covered about 900 km2 to understand the spatial pattern of the slope movements and to identify triggering parameters we correlated surface dynamics with the tectono geomorphic processes and lithologic conditions of the active front of the alai range we observed spatially continuous constant hillslope movements with a downslope speed of approximately 71 mm year 1 velocity our findings suggest that the lithological and structural framework defined by protracted deformation was the main controlling factor for sustained relief and consequently downslope mass movements the analysed structures revealed integration of a geological structural setting with the superposition of cretaceous paleogene alternating carbonatic and clastic sedimentary structures as the substratum for younger less consolidated sediments this type of structural setting causes the development of large scale gravity driven dsgsd and slow mass movement surface deformations with clear scarps and multiple crest lines triggered planes for large scale deep mass creeps and these were related directly to active faults and folds in the geologic structures our study offers a new combination of insar techniques and structural field observations along with morphometric and seismologic correlations to identify and quantify slope instability phenomena along a tectonically active mountain front these results contribute to an improved natural risk assessment in these structures

pliocene to quaternary deformation in south east sayan siberia initiation of the tertiary compressive phase in the southern termination of the baikal rift system the south east sayan area wof the lake baikal is subjected to a very complex tectonic setting where the extensional stress field of the baikal rift system meets the compressional stress field generated by the india asia collision further south using satellite images aerial photographs srtm dem field mapping of geomorphological structures and published neotectonics and geological data we show that most of the relief in the se sayan initiated during late pliocene pleistocene through compressive reactivation of inherited structures by late quaternary clockwise rotation of the compressive field generated strike slip faulting and local secondary extension still within a general compressional stress field we demonstrate that the formation of the small scale extensional basins within the east sayan range is not linked to general the extension in the baikal rift system nor to a possible asthenospheric plume acting at the base of the crust but rather to the rotation of small rigid tectonic blocks driven by the compression

rapid locking of tectonic magnetic fabrics in weakly deformed mudrocks abstract the anisotropy of magnetic susceptibility ams has provided important insights into early deformation conditions in compressive settings through characterization of tectonic fabrics in mudrocks that appear otherwise undeformed the validity of these insights relies on the assumption that tectonic fabrics are rapidly locked shortly after sediment deposition however the time lag between deposition and the tectonic overprint has yet to be quantified to verify this assumption here we present ams data from late holocene sediments recovered in two cores from lake issyk kul in the kyrgyz tien shan fold and thrust belt these sediments in which magnetic fabrics reflect the preferred orientation of phyllosillicates have typical tectonic magnetic fabrics with varying degrees of tectonic overprint likely controlled by small scale active faults the mean orientation of the susceptibility maxima parallels neighbouring active thrust faults and is perpendicular to the geodetically derived local shortening direction the age model for one of the studied cores which is based on 7 calibrated accelerator mass spectrometer radiocarbon dates indicates that sediments as young as 25 yr record this clear tectonic fabric which is locked within sediments older than 1180 cal yr bp our demonstration of rapid locking of tectonic fabrics in weakly deformed mudrocks shortly after deposition provides the required validation of their reliability for tectonic studies and opens new opportunities for providing quantitative insights into the relationship between magnetic ellipsoids shortening rates and stress directions in compressive settings

hydrochemical relationships in groundwater from central sao paulo state brazil groundwater samples from different aquifers occurring at center northeast portion of sao paulo state brazil were collected and chemically analyzed the waters leaching mesozoic sediments are generally more acid phaverage 5 9 and have lower values for total dissolved solids tdsaverage 105 mg l than those obtained for waters leaching paleozoic sediments of tubarao group first degree trend surfaces revealed that the deeper tubular wells occur towards east southeast and exploit paleozoic sediments as well fractured fissured diabases basalts whereas the tubular wells in the west northwest region are shallower piper diagrams indicated that the majority of the waters are a blend of waters from different lithologies significant correlations were found among nitrate chloride and bicarbonate suggesting the occurrence of some anthropogenic inputs whereas elevated alpha activity of geogenic 226ra indicated the need of a broad radiometric survey in the area

basin evolution in a folding lithosphere altai sayan and tien shan belts in central asia abstract central asia is a classical example for continental lithospheric folding in particular the altay sayan belt in south siberia and the kyrgyz tien shan display a special mode of lithospheric deformation involving decoupled lithospheric mantle folding and upper crustal folding and faulting both areas have a heterogenous crust with a long history of accretion collision subsequently reactivated as a far field effect of the indian eurasian collision thanks to the youthfulness of the tectonic deformation in this region peak deformation in late pliocene early pleistocene the surface expression of lithospheric deformation is well documented by the surface topography and superficial tectonic structures a review of the paleostress data and tectono stratigraphic evolution of the kurai chuya basin in siberian altai zaisan basin in kazakh south altai and issyk kul basin in kyrgyz tien shan suggests that they were initiated in an extensional context and inverted by a combination of fault controlled deformation and flexural folding in these basins fault controlled deformation alone appears largely insufficient to explain their architecture lithospheric buckling inducing surface tilting uplift and subsidence also played an important role they form typical basins in a folding lithosphere flb their characteristic basin fill and symmetry inner structure folding wavelength and amplitude thermal regime time frame are examined in relation to basement structure stress field strain rate timing of deformation and compared to existing modelling results

tracking the multi stage exhumation history of the western chinese tianshan by apatite fission track aft dating implication for the preservation of epithermal deposits in the ancient orogenic belt abstract the western chinese tianshan located in the southern domain of the central asian orogenic belt caob was originally established by multiple accretion collision processes in the paleozoic and was modified by complicated intracontinental tectonic evolution in the mesozoic to cenozoic understanding the timing and mechanism of the latter geological processes is critical to unravel the preservation conditions of the epithermal deposits in the western chinese tianshan this work presents new apatite fission track aft data for three mountain ranges keguqinshan wusunshan and nalatishan of the western chinese tianshan to track their exhumation history our aft data gave a wide range of ages from 76 8 5 5 ma to 182 3 9 9 ma and the mean confined fission track lengths are between 9 8 0 5 m and 12 3 0 2 m the new data in combination with the thermal history modeling results allow us to summary three main episodes of exhumation in the western chinese tianshan including the early permian 300 280 ma late triassic late jurassic 230 140 ma and late oligocene early miocene 30 20 ma the first episode may have been caused by terrane accretion collision in the late paleozoic leading to uplift of the keguqinshan that supplied abundant sediments to form a critical cover of ca 4 km thick on these epithermal deposits the second episode was likely related to closure of the mongol okhotsk ocean in the mesozoic and an extremely slow exhumation rate ca 0 0083 mm y as well as a moderate erosion of ca 0 8 km thick are estimated the last episode is regarded to be the result of collision between the indian plate and the eurasia plate in the cenozoic and this significant tectonic event triggered rapid exhumation up to ca 0 1 mm y of the whole region in the western chinese tianshan which removed more than ca 3 2 km pre cenozoic sedimentary cover and sent the epithermal deposits to the subsurface level

the bogeda shan uplifting evidence from multiple phases of deformation abstract the current topography of central asia is considered to have resulted from crustal shortening related to the ongoing india asia collision that started in the early tertiary period the bogeda shan a northeastern branch of the tian shan located in northwest china has several summits higher than 5000 m the northern piedmont of the bogeda shan exhibits remarkable deformation features that remain poorly studied this study documents three phases of tectonic deformation in the bogeda shan that are related to the far field effects of collisions along the southern eurasian margin detailed field observations show that the intensively folded upper permian strata are covered by a subhorizontal lower jurassic layer thus indicating a triassic tectonic event that is probably related to the onset of the uplift in the bogeda shan during a cimmerian orogenic episode d1 a seismic profile suggests that this deformation episode was followed by the late jurassic early cretaceous deformation d2 which is characterized by wide wavelength folds overlaid by undeformed cretaceous layers cenozoic thrusts were also observed in the northern piedmont of the bogeda shan d3 this study demonstrates that the onset of uplift in the bogeda shan began in the early mesozoic and separated the turfan hami basin from the junggar basin a new tectonic evolution model of the bogeda shan was reconstructed by these three tectonic phases this work indicates that the current topography of the bogeda shan and its surrounding area was the result of multiple phases of deformation related to successive collisions at the southern eurasian margin

large ancient earthquakes in the western issyk kul basin kyrgyzstan northern tien shan abstract new paleoseismological and archaeoseismological data from the western issyk kul basin of kyrgyzstan northern tien shan provide new insights on active fault in the actively deforming basement involved thrust system of central asia newly discovered fault scarps follow south and north dipping thrust faults which delineate the kyrgyz and kungey ranges bordering the issyk kul basin motion on these faults generated earthquakes with magnitudes 6 2 7 6 and msk 64 shaking intensities viii xi deformation observed in the zone of the toguz bulak fault results from two holocene earthquakes and another event that occurred about 8000 yr bp two more events at 13 000 and 3000 yr bp deformed the northeastern periphery of the kyzyl ompul uplift archaeoseismological research in the northern sary bulun settlement in the western periphery of the boz barmak uplift revealed traces of another earthquake of msk 64 shaking intensity i viii dating back to the 12th century the obtained data correlates well with results of previous paleoseismological and archeoseismological studies they show that in the northern tien shan there were clusters of strong earthquakes with ages of 14 13 8 4 3 ka ago and in the 11 12th centuries ad divided by periods of 4 5 ka we infer that coseismic slip on these faults may have formed a tectonic dam at the edge of the basin through growth of the boz barmak uplift and this dam ultimately deflected the chu river into its modern channel which bypasses the lake lacustrine sediments in the northeastern periclinal segment of the boz barmak uplift bear signatures of soft sediment deformation structures seismites corresponding to seven m 5 5 5 i vi vii earthquakes timed at about 20 000 yr bp

radioelements radiogenic helium and age relationships for groundwaters from the granites at stripa sweden abstract the solution of radioelements and radiogenic 4he by groundwaters in fractured rocks is dependent upon the radioelement distribution in the rock matrix and the extent of the rock water interface the 234 u 238 u activity ratio and the dissolved u rn and he contents of such groundwaters respond to changes in the flow regime with time although 234 u 238 u activity ratios change with groundwater residence time as a consequence of 234th recoil induced solution of 234u the activity ratio is strongly influenced by the u distribution within fractures by the extent of the rock water interface and by the amount of 238u in solution a model for the quantitative evaluation of these effects is presented groundwaters from depths up to 880 m in the stripa granite have variable dissolved uranium contents and 234 u 238 u activity ratios the uranium geochemistry is primarily determined by variations in flow path rather than by groundwater age dissolved radiogenic 4he in the groundwaters increases with their depth of origin and is dependent upon the u content of the granite and upon its fracture porosity it increases with groundwater residence time but movement of 4he by diffusion and transport processes make the actual groundwater age indeterminate

the pamir hindu kush seismic zone as a strain marker for flow in the upper mantle we introduce a new hypothesis to explain the unusual pattern of intermediate depth earthquakes in the pamir hindu kush region of central asia in our model the seismicity of the zone is defined by a remnant piece of oceanic crust that became neutrally buoyant and now hangs in the mantle underneath the center of the active mountain belt we interpret an abrupt cutoff in seismicity shallower than 70 km under the pamir as evidence that the slab has become decoupled from the surface deformation and we suggest that the remnant slab has acted as a strain marker for flow in the upper mantle the contortion of the slab can be explained by superimposed vertical and lateral simple shear related to the western edge of the indian plate this model requires relatively low strain rates of the order of 10 15 s 1 consistent with strain rates estimated from earthquake moment release in benioff zones in contrast the double facing subduction zone model applied by a number of previous authors requires strain rates of the order of 10 13 s 1 which are much higher than inferred strain rates in subducting slabs the results are important for understanding mantle dynamics providing a unique way to measure strain in the upper mantle the implied flow field also has significant implications for the kinematics of the entire collisional plate boundary in tibet and the tien shan

the mechanism of 234u238u activity ratio enhancement in karstic limestone groundwater departamento de petrologia e metalogenia universidade estadual paulista campus de rio claro unesp sao paulo

new evidence for active tectonics at the boundary of the kashi depression china from time series insar observations abstract kashi depression is one of the most complex active tectonic areas in the southern flank of tianshan china due to the lack of ground observations the boundary of basin mountain transition zone and the interseismic activity of the tianshan have not been clearly determined in this study 48 envisat advanced synthetic aperture radar asar imagery acquired from 2003 to 2010 are used to construct interferograms for measuring high resolution interseismic deformation in the kashi depression area a global atmospheric model era interim provided by the european center for medium range weather forecast ecmwf and a global network orbital correction are applied to remove atmospheric effect and the long wavelength orbital errors respectively for the interferograms interferometric sar time series with atmospheric estimation model insar ts aem are then used to obtain a deformation rate map for the kashi depression area the insar rate map indicates that the north part of south atushi fault has 3 mm year uplift relative to that of the south part this result manifests the main tectonic deformation potentially occurs along the southern atushi fault based on a simple edge dislocation model the dip angle of 31 0 6 slip rate of 2 3 0 1 mm year and locking depth of 10 6 0 4 km for the southern atushi fault between tianshan orogenic belt and the kashi depression are obtained this modeling result shows in good agreement with the insar derived rates our results show that the southern atushi fault is the main active fault in block boundary region between the south of tianshan and the tarim basin

proterozoic mesozoic history of the central asian orogenic belt in the tajik and southwestern kyrgyz tian shan u pb 40ar 39ar and fission track geochronology and geochemistry of granitoids multimethod geochronology u pb zircon 40 ar 39 ar hornblende biotite feldspar apatite fission track on granitoids gneisses and cenozoic intramontane basin clastics of the gissar alai ranges south tian shan collisional belt west of the talas fergana fault elucidates a history of neoproterozoic magmatism late paleozoic magmatism and metamorphism and mesozoic cenozoic thermal reactivation zircon core and grain interior u pb ages of ca 2 7 2 4 2 2 1 7 1 1 0 85 and 0 85 0 74 ga tie the early evolution of the gissar alai ranges to that of the tarim craton at least part of the gissar range crystalline basement the garm massif shows u pb zircon crystallization ages of ca 661 552 ma median ca 609 ma again suggesting a tarim craton connection tarim collided with the middle tian shan block at ca 310 305 ma completing the protracted formation of the south tian shan collisional belt the massive gissar range granitoids intruded later ca 305 270 ma contemporaneous with peak barrovian type metamorphism in the garm massif rocks major and trace element compositions suggest that the gissar granitoid melts have continental arc affinity zircon e hf and whole rock e nd values of 2 1 to 6 9 and 2 7 to 7 2 respectively and hf isotope crustal model and nd isotope depleted mantle model ages of ca 1 0 1 2 and ca 1 1 2 2 ga respectively suggest significant input of precambrian crust in the gissar granitoid and garm orthogneiss melts consistent with the u pb ages of inherited and detrital zircons the distinct ca 661 552 ma garm gneiss crystallization ages and the ca 1 0 2 2 ga model ages and the lack of 2 4 3 4 ga model ages tie the garm gneisses and the reworked crust of the gissar range to the northern rim the kuqa and kolar sections of the tarim craton suggesting a united karakum tarim craton although about contemporaneous with widespread postcollisional magmatism in the entire tian shan the large volume and short duration of the gissar range magmatism including crustal thickening and prograde metamorphism during tarim craton middle tian shan block collision and formation and closure of an oceanic back arc basin the gissar basin indicate its origin in a distinct setting combined this likely resulted in midcrustal melting and upper crustal batholith emplacement mafic dikes and pipes intruded at ca 256 238 ma median ca 241 ma the source region of the parental melts was within the asthenospheric mantle the simplest interpretation for these basanites is that they were part of the tarim flood basalt province this would extend this province westward from the tarim craton into the southwestern tian shan and imply that the relatively short lived flood basalt event ca 290 270 ma was followed by much less voluminous but longer lasting hotspot magmatism the 40 ar 39 ar and detrital apatite fission track dates outline post gissar alai range granitoid emplacement cooling cimmerian collision events at the southern margin of asia late cretaceous crustal extension and local magmatism and early cenozoic shortening and burial in the far field of the india asia collision

late paleozoic emplacement and meso cenozoic reactivation of the southern kazakhstan granitoid basement abstract the ili balkhash basin in southeastern kazakhstan is located at the junction of the actively deforming mountain ranges of western junggar and the tien shan and is therefore part of the southwestern central asian orogenic belt the basement of the ili balkhash area consists of an assemblage of mainly precambrian microcontinental fragments magmatic arcs and accretionary complexes eight magmatic basement samples granitoids and tuffs from the ili balkhash area were dated with zircon u pb la icp ms and yield carboniferous to late permian 350 260 ma crystallization ages these ages are interpreted as reflecting the transition from subduction to post collisional magmatism related to the closure of the junggar balkhash ocean during the carboniferous early permian and hence to the final late paleozoic accretion history of the ancestral central asian orogenic belt apatite fission track aft dating of 14 basement samples gneiss granitoids and volcanic tuffs mainly provides cretaceous cooling ages thermal history modeling based on the aft data reveals that several intracontinental tectonic reactivation episodes affected the studied basement during the late mesozoic and cenozoic late mesozoic reactivation and associated basement exhumation is interpreted as distant effects of the cimmerian collisions at the southern eurasian margin and possibly of the mongol okhotsk orogeny in se siberia during the jurassic cretaceous following tectonic stability during the paleogene inherited basement structures were reactivated during the neogene constrained by miocene aft ages of 17 10 ma this late cenozoic reactivation is interpreted as the far field response of the india eurasia collision and reflects the onset of modern mountain building and denudation in southeast kazakhstan which seems to be at least partially controlled by the inherited basement architecture

particle size scales and classification of sediment types based on particle size distributions review and recommended procedures this paper provides a review of different particle size scales size class terminology and particle size distribution textural classification schemes which are widely used in sedimentology geomorphology soil science aquatic ecology and civil engineering it is concluded that a revised system of size class nomenclature based on the udden 1898 and wentworth 1922 schemes provides the most logical and consistent framework for use with sediments and a wide range of other particulate materials a refined scheme is proposed which has five first order size classes boulder gravel sand silt and clay each of which has five second order subdivisions with limits defined at one phi intervals the scheme is simple and intuitively easy to understand the paper also provides a review of previous schemes that have been proposed to describe and classify sediments on the basis of the proportions of gravel sand and mud or sand silt and clay using trigons also termed ternary diagrams many of these schemes do not have a logical basis and provide limited or uneven resolution new gravel sand and mud and sand silt and clay classification systems are proposed that are both more logical and provide greater discriminatory power than previous schemes they are therefore more suitable for use in environmental and forensic investigations a new microsoft excel program freely available to download from http www kpal co uk allows rapid classification of sediments based on the proportions of gravel sand and mud and sand silt and clay proportions and graphical comparison of the data for different sample groups

new evidence on the neogene uplift of south tianshan constraints from the u th he and aft ages of borehole samples of the tarim basin and implications for hydrocarbon generation we identified a neogene rapid uplift denudation event of the south tianshan based on apatite u th he and apatite fission track aft ages in tertiary rocks of the tarim basin using borehole samples the u th he thermochronology can be used to reveal the tectono thermal events with lower temperature than that of aft thermochronology and has not been used previously to study the uplift of the tianshan mountain using these data we show the relationship between the uplift of the south tianshan and the subsidence deposition of the northern tarim basin during the neogene the apatite helium ages reveal the migration of uplift erosion and deposition in the northern tarim basin a rapid uplift of the south tianshan during the miocene and a corresponding rapid subsidence in the northern tarim basin occurred however in the pliocene the kuqa depression and south tianshan uplifted and eroded at the same time and in turn provided the detrital source rocks for the northern uplift of the tarim basin in contrast to earlier studies we arrive at the conclusion that the south tianshan experienced rapid uplift in the miocene based on u th he data of apatite obtained from borehole samples collected in the tarim basin itself and not from the bordering mountain chain combined apatite u th he and fission track thermochronometry enables reconstruction of thermal histories of sedimentary rocks between 40 and 120 c and this has implications for the generation of liquid hydrocarbon in the 65 120 c range in the basin thermal and burial histories of typical samples were also modelled to show the rapid uplift in our study our works not only provide a new evidence for the south tianshan uplift but also indicate that there is a coupling between uplift and subsidence in the south tianshan and adjacent northern part of the tarim basin which controlled hydrocarbon accumulation in the kuqa depression and northern uplift of the tarim basin

geochemical evolution of a palaeolaterite the interbasaltic formation northern ireland abstract the interbasaltic laterites of northern ireland were formed during a period of relative volcanic inactivity by extensive chemical weathering of tertiary basalts they reach a maximum thickness of 30 m and once provided a major source of iron and aluminium ore an extensive database comprising major minor and trace elements has been compiled for 240 samples in order to study the effects of weathering in terms of the changes in whole rock chemistry and mineralogy from basalt through to iron rich crust percolating waters caused degradation of the parent basalt mineralogy and precipitation of neoformed phases principally through incongruent dissolution processes primary olivine plagioclase feldspar and augite were successively broken down and replaced by a mineral assemblage consisting of hematite gibbsite goethite anatase meta halloysite and kaolinite changes in mineralogy facilitated concomitant changes in element concentrations mass balance calculations indicate that all elements were depleted in the iron crust enrichment of al loi cr cu and v occurred in the laterite horizon while enrichment of al loi ba ce cr cu ni and rb occurred in the lithomarge notably yttrium was found to be mobile indicating that weathered basalts should not be used in discrimination of original tectonic environments the severe leaching conditions evidenced by yttrium depletion local aluminium redistribution and iron crust formation are indicative of weathering under a humid sub tropical monsoon climate

thermo tectonic history of the issyk kul basement kyrgyz northern tien shan central asia abstract lake issyk kul occupies a large late mesozoic cenozoic intramontane basin between the mountain ranges of the northern kyrgyz tien shan these ranges are often composed of granitoid basement that forms part of a complex mosaic assemblage of microcontinents and volcanic arcs several granites from the terskey kungey trans ili and zhetyzhol ranges were dated with the zircon u pb method shrimp la icp ms and yield concordant late ordovician silurian 456 420 ma emplacement ages these constrain the caledonian accretion history of the northern kyrgyz tien shan in the amalgamated palaeo kazakhstan continent the ancestral tien shan orogen assembled in the early permian when final closure of the turkestan ocean ensued collision of palaeo kazakhstan and tarim a late palaeozoic structural basement fabric formed and middle late permian post collisional magmatism added to crustal growth of the tien shan permo triassic cooling 300 220 ma of the ancestral tien shan was unraveled using 40 ar 39 ar k feldspar and titanite fission track ft thermochronology on the issyk kul granitoids apatite thermochronology ft and u th sm he applied to the broader issyk kul region elucidates the meso cenozoic thermo tectonic evolution and constrains several tectonic reactivation episodes in the jurassic cretaceous and cenozoic exhumation of the studied units occurred during a protracted period of intracontinental orogenesis linked to far field effects of late jurassic cretaceous accretion of peri gondwanan blocks from the tethyan realm to eurasian following a subsequent period of stability and peneplanation incipient building of the modern tien shan orogen in northern kyrgyzstan started in the oligocene according to our data intense basement cooling in distinct reactivated and fault controlled sections of the trans ili and terskey ranges finally pinpoint important miocene pliocene 22 5 ma exhumation of the issyk kul basement late cenozoic formation of the tien shan is associated with ongoing indentation of india into eurasia and is a quintessential driving force for the reactivation of the entire central asian orogenic belt

understanding groundwater sources and movement using water chemistry and tracers in a low matrix permeability terrain the cretaceous chalk ulster white limestone formation northern ireland abstract the cretaceous chalk ulster white limestone formation uwlf in northern ireland has been diagenetically altered to a hard low porosity low matrix permeability rock it subcrops extensive beneath thick horizontal tertiary basalt lavas but has a restricted strip of outcrop approximately 80 km2 around the periphery of the overlying igneous rock despite its nature and location numerous springs issue from the chalk and are used for public and local supply although little is known about the origin of the groundwater or the type of flow within the chalk we have addressed these unknowns using hydrogeochemical data from both rock types and surface stream waters and fluorescent dye tracing we have demonstrated that leakage recharge from the basalt to the chalk accounts for less than 20 of the total water issuing from the chalk springs using geochemical mass balance of conservative species and discharge data the majority of the discharge derives from streams coming off the basalt and entering sink holes in the chalk aquifer field and water tracing evidence shows that groundwater flow in the chalk is dominated by conduit and fissure flow near to the outcrop areas karstification has been widespread near outcrop but has not ocurred in the sub basalt region beneath the basalts the chalk exhibits different hydraulic properties due to the reduced recharge and dissolution potential that has prevented extensive development of fissure permeability in the uwlf the chalk aquifer thus appears to be strongly zoned in terms of the source of water flow regime and recharge rate

electric and magnetic tomographic approach for the geophysical investigation of an unexplored area in the archaeological site of pompeii southern italy the joint application of electric and magnetic techniques for near surface exploration represents a very useful tool for archaeological investigation and can provide a quantitative contribution to describe the spatial distribution of buried objects in this work we show a new advanced tomographic approach based on the parallel inversion of magnetic and electric observed data aimed at the reconstruction of the subsoil of a still unexplored area of the archaeological site of pompeii southern italy the survey was performed in collaboration with pompeii s archaeological commission the comparison between the results obtained from the tomographic inversions of both electrical and magnetic data was carried out in terms of the data inversions which allowed us to obtain information about the location of the buried geophysical sources in the investigated subsoil the results obtained seem to be in a good agreement both for the position of the geophysical sources and for their dimensions

sedimentology and magnetostratigraphy of the tierekesazi cenozoic section in the foreland region of south west tian shan in western china abstract the geology of tian shan provides an excellent example for understanding the intracontinental orogeny in the context of indian eurasian convergence previous studies leave much space in basinfill deposition process to be assessed in the regions west to the talas fergana fault tff we improve the understanding by conducting new investigations on sedimentology and magnetostratigraphy in the tierekesazi section of the foreland region of south west tian shan four lithofacies have been identified i marine lithofacies from the aertashi to bashibulake formations ii lacustrine to fluvial plain lithofacies from the keziluoyi to the middle pakabulake formations iii alluvial sand gravel sheet lithofacies in the upper pakabulake formation and iv conglomerate lithofacies from the atushi to xiyu formations magnetostratigraphic analysis accompanied with biostratigraphic correlation indicates that four lithofacies cover age intervals of ca 65 ma to 34 ma ca 22 1 ma to 12 ma 12 ma to 5 2 ma and 5 2 ma to approximately present with the sediment accumulation rates increasing from ca 2 4 3 3 3 5 compacted decompacted cm ka in the lithofacies i to 12 3 16 17 cm ka in the lithofacies ii to 16 3 19 5 20 6 cm ka in the lithofacies iii and finally to 22 8 22 8 cm ka in the lithofacies iv these results suggest three episodes of sedimentary events combined with previous results these episodes of sedimentary events are attributed to tectonic activities that are widespread along south tian shan we speculate that the oligo miocene boundary event more directly and likely marks the initial underthrusting of the tarim block beneath the south tian shan the mid miocene and mio pliocene boundary events although approximately synchronous between the regions east and west to the tff have different structural expressions in the two regions such difference is proposed to cause the dextral slipping of the tff and more fundamentally likely be driven by the northward indentation of the pamir at this time

magnetostratigraphic record of the early evolution of the southwestern tian shan foreland basin ulugqat area interactions with pamir indentation and india asia collision the tian shan range is an inherited intracontinental structure reactivated by the far field effects of the india asia collision a growing body of thermochronology and magnetostratigraphy datasets shows that the range grew through several tectonic pulses since 25 ma however the early cenozoic history remains poorly constrained the time lag between the eocene india asia collision and the miocene onset of tian shan exhumation is particularly enigmatic this peculiar period is potentially recorded along the southwestern tian shan piedmont there late eocene marine deposits of the proto paratethys epicontinental sea transition to continental foreland basin sediments of unknown age were recently dated we provide magnetostratigraphic dating of these continental sediments from the 1700 m thick mine section integrated with previously published detrital apatite fission track and u pb zircon ages the most likely correlation to the geomagnetic polarity time scale indicates an age span from 20 8 to 13 3 ma with a marked increase in accumulation rates at 19 18 ma this implies that the entire oligocene period is missing between the last marine and first continental sediments as suggested by previous southwestern tian shan results this differs from the southwestern tarim basin where eocene marine deposits are continuously overlain by late eocene oligocene continental sediments this supports a simple evolution model of the western tarim basin with eocene oligocene foreland basin activation to the south related to northward thrusting of the kunlun shan followed by early miocene activation of northern foreland basin related to overthrusting of the south tian shan our data also support southward propagation of the tian shan piedmont from 20 to 18 ma that may relate to motion on the talas fergana fault the coeval activation of a major right lateral strike slip system allowing indentation of the pamir salient into the tarim basin suggests far field deformation from the india asia collision zone affected the tian shan and the talas fergana fault by early miocene

late cretaceous palaeogene topography of the chinese tian shan new insights from geomorphology and sedimentology abstract the cenozoic growth of the intra continental tian shan range initiated during the late eocene oligocene and led to a tectonic reactivation of the complex palaeozoic and mesozoic lithospheric structure due to the very low erosion rates linked to the semi arid climate that characterised the tian shan region during most of the cenozoic the topography of the range is not at equilibrium with deformation fragments of pre orogenic low relief surfaces are preserved among the late cenozoic alpine type topography using field observations and satellite image mapping of those fragments as well as sedimentology and biostratigraphic analysis we show that the pre oligocene topography of the tian shan region was indeed complex combining hundreds of metres to one and a half kilometre high reliefs with a multi phased mesozoic planation surface incised by late mesozoic paleo valleys the occurrence of several metres thick late cretaceous palaeogene calcareous paleosols in the basins surrounding the range further implies a semi arid climate very low subsidence rates and no uplift at that time late cretaceous and early miocene fossil records in the northern tian shan suggest a possible connection even if episodic between the drainage system of the south junggar foreland basin and the proto paratethys sea to the west a renewed late eocene early oligocene sedimentation probably marks the onset of the tian shan uplift we argue that in addition to the growth of the pamir and western kunlun ranges this incipient uplift was one of the driving mechanisms for the final retreat of the proto paratethys sea from the tarim basin this regression apparently did not change the climate in the studied area because semi arid conditions seem to prevail at least since the late cretaceous finally the tian shan uplift remained very limited up to the miocene as revealed by the occurrence of burdigalian lake deposits preserved in the paleo valleys inside the present day range in contrast post early miocene deformation of the northern tian shan has produced 4000 to 5000 m of differential vertical movement between the uplifted range and the subsiding proximal foreland basin

high resolution study on the hydrochemical variations caused by the dilution of precipitation in the epikarst spring an example spring of landiantang at nongla mashan china in addition to rainfall high resolution measurements of water level ph specific conductivity and temperature of landiantang epikarst spring at nongla mashan county in guangxi province china were recorded in summer rainy season by using a data logger with time interval of fifteen minutes water from the spring issues along a karst conduit during the rainstorms in summer it was found that the ph and temperature of landiantang spring increased while its specific conductivity decreased as hco3 ca2 and mg2 are the dominant ions linear relationships between concentrations of those ions and specific conductivity were developed according to the ion concentrations from the linear relationships the saturation indexes of calcite sic the saturation indexes of dolomite sid and co2 partial pressure log text p text co text 2 of the spring were calculated results indicated that the log text p text co text 2 of the spring during the rainstorms was lower than that without rain and its sic and sid was also lower combined with the characteristics of the epikarst zone it was inferred that the above results were caused by the dilution of rainwater because overland flow with high ph due to neutralization of carbonate rock dusts in the air to rainwater and low specific conductivity traveling through the conduit rapidly during rainstorms showed greater influences on the hydrochemical variations of the epikarst spring

mineralogy chemistry and palaeoenvironmental significance of an early tertiary terra rossa from northern ireland a preliminary review abstract early tertiary basalts of the antrim plateau have preserved palaeosols developed on late cretaceous limestone these palaeosols include dark red clays and clays with flints that are rich in silica and contain a complex clay mineral assemblage of 2 1 lattice clays kaolinite and sepiolite they occur in infilled solution hollows and joints can be associated with a rudimentary tower karst and are similar in appearance and composition to present day mediterranean terra rossa soils elsewhere grey flint rich clay sized material dominated by silica and kaolinite developed on an undulating landscape sometimes now capped by a lignite horizon deposits and the palaeolandscape suggest a humid tropical to sub tropical environment contrary to previous published inferences of arid conditions but corresponding to humid tropical conditions proposed for the formation of overlying inter basaltic soils

impact of range parallel sediment transport on 2d thermo mechanical models of mountain belts application to the kyrgyz tien shan evolving mountain belts dynamics is very sensitive to surface processes the surface processes affect tectonics by enhancing crust exhumation and thermal weakening and depositing soft yet cold sediments in surrounding basins while 2d plane strain models approximate cylindrical tectonic structures well simple 1d mass transfer cannot capture erosion sedimentation complexity the eastern kyrgyz tien shan where structures basins and exhumation rates are well constrained is used here to illustrate this issue thermo mechanical models demonstrate that 1d transport cannot adjust both basin geometry and apatite fission track exhumation ages when out of plane sediment transfer is considered the amount of evacuated sediment delays or accelerates the formation of new faults affecting the relative timing of exhumation for our case study lateral drainage must evacuate 80 of the sediments to match the geological constraints which is consistent with other source to sink analyses this indicates that lateral drainage should not be neglected in regional 2d models