crustal deformation along the altyn tagh fault system western china from gps we collected gps data from the southern tarim basin the qaidam basin and the western kunlun shan region between 1993 and 1998 to determine crustal deformation along the altyn tagh fault system at the northern margin of the tibetan plateau we conclude from these data that the altyn tagh is a left lateral strike slip fault with a current slip rate of 9 mm yr in sharp contrast with geological estimates of 20 30 mm yr this contrast poses an enigma because the gps data cover a wider region than the geologic data they might be expected to reveal somewhat more slip we also find that the tarim and qaidam basins behave as rigid blocks within the uncertainty of our measurements rotating clockwise at a rate of 11 and 4 5 nrad yr respectively with respect to the eurasia plate the rotation of the tarim basin causes convergence across the tian shan increasing progressively westward from 6 mm yr at 87 e to 18 mm yr at 77 e our data and other gps data suggest that the indo asia collision is mainly accommodated by crustal shortening along the main himalayan thrust system 53 and the tian shan contractional belt 19 eastward extrusion of the tibetan plateau along the altyn tagh and kunlun faults accommodates only 23 of the indo asia convergence

impact of tropical heat sources on the south american tropospheric upper circulation and subsidence the nonlinear adjustment of the wind and mass fields to idealized tropical heat sources is studied with a simple nonlinear primitive equation model with emphasis on the upper level circulation over south america and neighboring oceanic regions during the austral summer numerical experiments are performed with 1 an idealized symmetrical heat source in the amazon region 2 the asymmetry induced in source 1 by the sacz 3 the effect of the atlantic itcz off the amazon mouth 4 the african heat source 5 the west pacific source and 6 the central pacific source during the warm phase of enso the linear response is obtained through the reduction of the heat source by a factor of 10 and subsequent multiplication of the results by the same factor two basic questions are discussed 1 are localized heat sources important for the development of the observed cyclonic flow in the midequatorial atlantic and 2 where is the compensating subsidence associated with the amazon heat source located the nonlinearity helps organizing a weak cyclonic curvature in the midequatorial atlantic with the inclusion of source 2 the basic state generated by the west pacific source and primarily by the central pacific source has a large impact on the cyclonic curvature on the equatorial atlantic the compensating subsidence associated with the amazon source is concentrated on the southwest side of the source the sacz extension helps to enhance the subsidence over the northern argentina and the atlantic itcz enhances the subsidence over northeast brazil and central equatorial atlantic nonlinearity weakens the subsidence at the 500 hpa level inducing a more barotropic structure in the dynamical response to the heating

a generalization of gill s heat induced tropical circulation abstract in this note the local solution of gill for the symmetric and the antisymmetric heat sources and sinks is extended to the entire global tropical belt by the authors the symmetric and antisymmetric heating forced solutions of the motion field derived from the linearized shallow water equations describe many aspects of the winter and the summer monsoon circulations the extension provided here describes the response of tropical circulation to the global tropical heat sources and sinks retrieved from a satellite based field of the outgoing longwave radiation through regression algorithms such a prescribed field is expanded into a low order set of trigonometric functions in the zonal direction and parabolic cylinder functions along the meridional coordinate upon sequential substitution of these modes into the linearized shallow water equations on a beta plane it is possible to solve for the heating forced solutions in a closed analytical form for the entire tropics the solutions exhibit most

what are the sources of mechanical damping in matsuno gill type models the matsuno gill model has been widely used to study the tropical large scale circulations and atmosphere ocean interactions however a common critique of this model is that it requires a strong equivalent linear mechanical damping to get realistic wind response and it is unclear what could provide such a strong damping above the boundary layer this study evaluates the sources and strength of equivalent linear mechanical damping in the walker circulation by calculating the zonal momentum budget using 15 yr 1979 93 of daily global reanalysis data two different reanalyses ncep ncar and 15 yr ecmwf re analysis era 15 give qualitatively similar results for all major terms including the budget residual whose structure is consistent with its interpretation as eddy momentum flux convergence by convective momentum transport cmt the walker circulation is characterized by two distinct regions a deep convection region over the indo pacific warm pool and a shallow convection region over the eastern pacific cold tongue these two regions are separated by a strong upper tropospheric ridge and a strong lower tropospheric trough in the central pacific the resultant pressure gradient forces on both sides require strong approximately 5 10 days damping to balance them because coriolis force near the equator is too small to provide the balance in the deep convection region the damping is provided by cmt and advection together in both the upper and lower troposphere in the shallow convection region on the other hand the damping is provided mainly by advection in the upper troposphere and by cmt in the lower troposphere in other words the upperlevel tropical easterly jet and the low level trade wind are both braked by cmt these results support the use of strong damping in the matsuno gill type models but suggest that the damping rate is spatially inhomogeneous and the cmt related damping increases with the strength of convection implications for gcm s simulation of tropical mean climate are discussed

magnitude of post middle jurassic bajocian displacement on the central altyn tagh fault system northwest china the altyn tagh fault system a key structural feature in the tectonic collage of central asia is an active left lateral strike slip fault system however its age of initiation kinematic history and total magnitude of displacement are not well known middle jurassic nonmarine sedimentary rocks that crop out along the central segment of the altyn tagh fault were deposited in a contiguous tarim qaidam foreland style basin that was geodynamically linked to mesozoic contraction in the tian shan bei shan qilian shan and kunlun shan this study documents the best evidence of a piercing point to date consisting of an offset lacustrine shoreline demarcated by aalenian bajocian open lacustrine strata to the west and fluvial and alluvial strata of comparable age to the east detrital compositions palynology paleocurrents and lithostratigraphy support correlation of these sections restoration of this jurassic facies boundary indicates 400 60 km of post bajocian left lateral separation on the altyn tagh fault consistent with this result restoration of the jurassic shoreline aligns felsic plutons across the western segment of the altyn tagh fault system that may have been left laterally offset by 360 km these two pairs of offset features suggest that the current best estimate for net magnitude of post bajocian left lateral separation on the altyn tagh fault is about 360 km

shortening of lower crust beneath the ne tibetan plateau abstract we reprocessed a high resolution deep seismic reflection profile to reveal the detailed crustal structure of the junction between the qilian shan nan shan thrust belt and the hexi corridor basin in the ne tibetan plateau the profile shows that the moho discontinuity is characterized by complex dislocations and overlapping geometries restoration of the deformed moho discontinuity reveals 50 2 km 35 5 of cenozoic lower crustal shortening along the seismic profile compression of the lower crust produces crustal thickening of 12 8 km this demonstrates that lower crustal shortening plays a significant role in topographic uplift and crustal thickening at the ne margin of the tibetan plateau thus we propose a double layered shortening mechanism with decoupled deformation of upper crust and lower crust the proposed deformation mechanism differs from previous crustal shortening models for the northern eastern and northeastern tibetan plateau our model eliminates the need for lower crustal flow to explain topographic uplift along the ne margin of the tibetan plateau

deep structures and surface boundaries among proto tethyan micro blocks constraints from seismic tomography and aeromagnetic anomalies in the central china orogen abstract the qinling qilian orogen preserves the records of early paleozoic convergence among the proto tethyan micro blocks in this study we analyze the seismic velocity structure and the aeromagnetic anomalies in the qinling qilian orogen and its adjacent areas showing that the northernmost boundaries of these proto tethyan micro blocks are defined by the guyuan longshoushan fault in the qilian orogen and by the luonan luanchuan fault in the qinling orogen respectively the lithosphere north of the qinling qilian orogen subducted southward under the qinling qilian orogen the boundaries of the micro blocks in the qinling qilian orogen of the proto tethys domain are mostly ew or ne trending combined with early paleozoic geological records our results indicate that the south dipping low velocity anomaly under the alxa block and the south dipping high velocity ones under the north qilian orogen and the north china block might indicate that the alxa block the north qilian oceanic slab and the north china block subducted southward the south dipping high velocity anomaly under the north qilian orogen is interpreted as the remnant of the proto tethys ocean in that area however the north dipping low velocity anomaly under the south qinling and the north qinling orogens the qaidam block and the north dipping high velocity one under the yangtze and the bikou blocks suggest that the south qinling and the north qinling orogens the qaidam the yangtze and the bikou blocks subducted northward the present spatial framework of the qinling qilian orogen is related to early paleozoic convergence among the proto tethyan micro blocks

exhumation of the ultrahigh pressure continental crust in east central china cretaceous and cenozoic unroofing and the tan lu fault the orogenic architecture of the world s largest ultrahigh pressure exposure the hong an dabie mountains of the triassic qinling dabie orogenic belt is dominated by cretaceous and cenozoic structures that contributed to its exhumation from 30 km depth cretaceous magmatic crustal recycling 50 for the entire dabie and heating 250 to 700 c were most prominent in dabie and exhumation magmatism and cooling were all controlled by cretaceous transtension exhumation was accomplished principally by an asymmetric cordilleran type extensional complex in the northern dabie northern orthogneiss unit between 140 and 120 ma at rates as fast as 2 mm yr and average horizontal stretching rates of up to 6 mm yr cretaceous reactivation occurred within a regional transtensional strain field as a result of far field collisions and pacific subduction the onset of crustal extension was preceded and possibly facilitated by a reheating of the hong an dabie crust 140 ma coeval with the onset of voluminous magmatism in eastern china 145 ma which resulted from a change in pacific subduction from highly oblique to orthogonal the tan lu continental scale fault was a normal fault zone in the mid cretaceous 110 90 ma and underwent 5 4 km dip slip and 4 km throw in the cenozoic during the india asia collision the qinling dabie belt acted as the structural discontinuity between the strike slip dominated escape tectonics south of the qilian qinling dabie belt and the rifting dominated tectonism north of it the most prominent cretaceous and cenozoic structures of the hong an dabie the xiaotian mozitang and the jinzhai fault zones respectively reactivated major lithospheric structures of the triassic orogen i e the huwan detachment zone and the suture

is the north altyn fault part of a strike slip duplex along the altyn tagh fault system although the altyn tagh fault system has played an important role in the indo asian collision its geometry and tectonic evolution remain poorly known between 86 and 92 e this system is at least 100 km wide and is bounded to the north and south by the north altyn and altyn tagh faults respectively mapping along the jianglisai reach of the north altyn fault indicates that miocene to pliocene motion was predominantly left to left reverse slip with transport vectors trending n45 60 e map relationships suggest that total offset on the fault is 120 km these results are inconsistent with previous models of the altyn tagh fault system in which oblique convergence along the northern margin of the tibetan plateau is partitioned into thrusting on the north altyn fault and left slip on the altyn tagh fault an alternative hypothesis is that the north altyn fault is the northern boundary of a transpressional strike slip duplex within which the structurally elevated altyn mountains were created our model suggests that transpressional deformation may be restricted to this strike slip duplex and need not characterize the entire margin

cenozoic cooling history and fluvial terrace development of the western domain of the eastern kunlun range northern tibet abstract the growth of the tibetan plateau resulted primarily from cenozoic india asia collision and continued convergence and thus the deformation timing and geomorphic evolution of northern tibet are critical to understanding the dynamics of orogenic plateau growth although previous studies have suggested that the altyn tagh shan and the eastern kunlun range of northern tibet have experienced differential faulting and exhumation history our knowledge of the temporal and spatial distribution of the growth of the northwestern tibetan plateau is still lacking in this study we integrate new geologic mapping low temperature themochronometry 18 apatite fission track ages and optically stimulated luminescence osl dating to provide constraints on the cenozoic cooling history of northwestern tibet and late quaternary fluvial terrace development we focus on where altyn tagh shan structures are juxtaposed against eastern kunlun range structures new fission track cooling ages from one traverse along the aksu river yielded three cooling age domains paleocene miocene and early pliocene with this new knowledge of 12 10 ma initiation of jianxiashan thrusting and exhumation we suggest a refined n s shortening rate of this thrust system of 2 0 2 4 mm yr and strain rates of 8 9 10 16 s 1 thermal history modeling suggests that the study area experienced two broad events including slow cooling through the aft paz since the early eocene and rapid cooling during the late miocene our osl dating results from the aksu drainage reflect two separate processes of aggradation and incision that occurred during the late pleistocene and holocene respectively which are interpreted to result from long term forcing of incision by a constant rate of tectonic uplift modulated by late quaternary climatic variations we interpret that this incision occurred at a rate of 1 mm yr which is faster than exhumation rates inferred from the aft data 0 3 0 5 mm yr these quaternary exhumation rates may reflect faster recent exhumation or uplift associated with the proximal altyn tagh fault in accordance with previous studies we present a refined cenozoic tectonic model for the evolution history of northern tibet the deformation pattern of northern tibet results from clockwise rotation of preexisting weaknesses and transpressional deformation along the kunlun fault and the haiyuan fault

formation and evolution of strike slip faults rifts and basins during the india asia collision an experimental approach the processes which have governed the formation and evolution of large tertiary strike slip faults during the penetration of india into eastern asia are investigated by means of plane strain indentation experiments on layered plasticine models the steady state deformation of plasticine obeys a power creep flow law e c t n the stress exponent n is between 6 and 9 at 25 c uniaxial plane strain tests on cubic specimens show that the growth of faults in layered plasticine results from strain softening a process observed for strain rates ranging from 3 5 10 5 to 3 6 10 3 s 1 fault or shear zones form after only 7 10 bulk strain subsequent deformation is controlled by the geometry of the fault pattern rather than the physical properties of the plasticine a series of nine plane strain indentation experiments shows the influence of boundary conditions as well as that of the internal structure of the plasticine model on the faulting sequence the ubiquity of strain softening in experimental deformation of a variety of rocks as well as the widespread occurrence of shear zones in nature suggest that long term deformation of the continental lithosphere may also be primarily influenced by the geometry of large faults which rapidly develop with increasing strain the deformation and faulting sequence observed in the plasticine indentation experiments may thus be compared to collision induced strikeslip faulting in asia particularly to total offsets and rates of movements on the faults the experiments simulate the evolution of the western ends of the strike slip faults which have probably been analogous to trench fault fault triple junctions the experiments also illustrate mechanisms for the formation of extensional basins such as the south china sea north china basin and andaman sea near active continental margins the basins which appear to absorb terminal offsets along major strike slip faults near such margins may result from mismatch between the sharply angular shape of the deformed continental edge and the more regularly curved trench along which the smoothly flexed oceanic lithosphere subducts the existence of distinct phases of strike slip extrusion corroborates the idea that the discontinuities in time which typify intracontinental tectonics and orogenic cycles may often result from strain localization and the ensuing discontinuous non steady state deformation of the continental lithosphere

tectonic evolution of the northeastern pamir constraints from the northern portion of the cenozoic kongur shan extensional system western china the late cenozoic kongur shan extensional system lies along the northeastern margin of the pamir at the western end of the himalayan tibetan orogen accommodating east west extension in the pamir at the northern end of the extensional system the kongur shan normal fault juxtaposes medium to high grade metamorphic rocks in both its hanging wall and footwall which record several mesozoic to cenozoic tectonic events schists within the hanging wall preserve a buchan metamorphic sequence dated as late triassic to early jurassic 230 200 ma from monazite inclusions in garnet metamorphic ages overlap with u pb zircon ages from local granite bodies and are interpreted to be the result of regional arc magmatism created by subduction of the paleo tethys ocean the northern portion of the footwall of the extensional system exposes an upper amphibolite facies unit 650 c 8 kbar which structurally overlies a lowgrade metagraywacke unit the high grade unit records late early cretaceous crustal thickening at ca 125 110 ma followed by emplacement over the low grade metagraywacke along a north northeast directed thrust prior to ca 100 ma together these results indicate signifi cant middle cretaceous crustal thickening and shortening in the northern pamir prior to the indo asian collision a third late miocene ca 9 ma amphibolite facies metamorphic event 650 700 c 8 kbar is recorded in footwall gneisses of the kongur shan massif north of the kongur shan massif rapid cooling in the footwall beginning at 7 8 ma is interpreted to date the initiation of exhumation along the kongur shan normal fault a minimum of 34 km of east west extension is inferred along the kongur shan massif based on the magnitude of exhumation since the late miocene 29 km and the present dip of the kongur shan normal fault 40 field observations and interpretation of satellite images along the southernmost segment of the kongur shan extensional system indicate that the magnitude of late cenozoic east west extension decreases signifi cantly toward the south this observation is inconsistent with models in which east west extension in the pamir is driven by northward propagation of the right slip karakoram fault suggesting instead that extension is driven by vertical extrusion due to topographic collapse radial thrusting along the main pamir thrust or oroclinal bending of the entire pamir region

structure and evolution of the himalaya tibet orogenic belt the 1981 french chinese expedition to tibet focused on the lhasa block extending earlier coverage 400 km north of the tsangpo suture the lhasa block stood between 10 and 15 n latitude over most of the upper cretaceous and eocene and if gondwanian in origin had detached from gondwana by early permian seismic profiles reveal a complex moho topography resulting both from multiple continental thrusting and large scale strike slip faulting subduction related granitoids representing mixtures of mantle and crustal components and anatectic granitoids have been analysed and dated this study emphasizes the role of smaller blocks in the accretion of the continental mosaic

an immediate response to the indian eurasian collision along the northeastern tibetan plateau evidence from apatite fission track analysis in the kuantan shan hei shan abstract the tibetan plateau offers an ideal region for understanding the processes of continental collision and related intracontinental deformation however when the cenozoic deformation was initiated in the present northeastern margin of the plateau 2000 km north to the indian eurasian collision front remains an issue in debate two competing end member models have been proposed involving immediate deformation response and progressive deformation propagation solving this problem partly relies on determining whether there was contemporaneous deformation with initial indian eurasian collision along the northeastern margin of the tibetan plateau in this study we employ apatite fission track aft analysis to shed new light on the exhumation history of the kuantan shan hei shan along the northeastern margin of the tibetan plateau with a motivation to determine whether deformation related exhumation during initial collision stage occurred in the region the 22 granite samples produce aft ages ranging from 22 3 2 6 ma to 175 18 ma and mean track lengths from 11 17 2 26 m to 13 63 1 93 m thermal history modeling indicates five episodes of rapid exhumation related cooling which took place in the early jurassic early cretaceous and late cretaceous during since the eocene and since the middle miocene the exhumation events prior to the cenozoic are attributed to far field responses of successive closure of fossil oceans and assembly of blocks along the southern margin of the eurasian continent the eocene exhumation along the kuantan shan hei shan is speculated to represent an immediate response to the initial indian eurasian collision these results lend support to the immediate deformation response model along the northeastern plateau the episodic exhumation observed in this study combined with previous geophysical findings implies that the kuantan shan hei shan represents the southern margin of the alashan block serving as a significant and long lived lithospheric weak zone susceptible to intracontinental deformation during episodes of far field tectonic event

a chlorine disinfectant for excess argon released from k felsspar during step heating abstract the release of excess 40 ar 40 ar e from virtually all alkali feldspars at low temperatures 40 ar 39 ar step heating experiments obscures potentially valuable age and thermal history information we report a method that takes advantage of the differential release of 40 ar e between contiguous isothermal heating steps due to the decrepitation of fluid inclusions and which permits derivation of a correction for the contaminating argon differences in age and cl k between successive temperature pairs commonly yield a single well correlated array on a 40 ar k versus cl k plot that identifies the cl correlated composition of 40 ar e 40 ar e cl affecting that sample eighteen of the twenty k feldspar samples we have measured yield a single 40 ar e cl component that varies from 1 1 10 3 to 4 2 10 6 making possible recovery of otherwise unobtainable thermochronological information the upper bound on the 40 ar e cl distribution of 10 3 may reflect ar saturation of pore fluids or the maximum duration between deuteric alteration and cooling below ar closure in k feldspar

the enigmatic yinshan fold and thrust belt of northern china new views on its intraplate contractional styles the east to east northeast trending yinshan belt lies within north china extending westward at least 1100 km from china s eastern coast to inner mongolia this intraplate jurassic cretaceous belt underwent contractional and normal faulting folding and contemporaneous terrestrial sedimentation and magmatism current views on its contractional deformational style favor relatively limited thick skinned faulting of archean basement and cover units these views are challenged however by recent discoveries in the eastern part of the belt of south directed ductile nappe formation and large displacement 40 45 km thin skinned northward thrust faulting both involving archean and younger rock units collision of the siberian and north china plates upon closure of a jurassic and early cretaceous mongolo okhotsk ocean more than 800 1100 km to the north may have been responsible for yinshan north south contraction some patterns of contraction e g jurassic cretaceous ductile nappe formation appear to have been influenced by a superposed magmatic regime related to westward subduction of a pacific basin plate beneath the north china plate

structure of the central altyn tagh fault revealed by magnetotelluric data new insights into the structure of the northern margin of the india asia collision abstract the altyn tagh fault atf is a left lateral strike slip fault that forms the northern margin of the tibetan plateau and plays a significant role in accommodating the convergence between the colliding indian and eurasian plates as a part of the fourth phase of the indepth project magnetotelluric mt data were collected across the central segment of the atf to determine the lithospheric scale structure of the fault system dimensionality analyses demonstrated that the mt data can be interpreted using two dimensional approaches but some localized 3 d effects are seen consequently both 2 d and 3 d inversions were carried out and a joint interpretation was made on the basis of these two types of models inversion models revealed two major conductors beneath the qaidam basin qb and altyn tagh range atr respectively the conductive region beneath the qb was interpreted as a ductile layer in the lower crust to upper mantle that might represent flow beneath the western margin of the qb whereas the large scale south dipping conductor beneath the atr is interpreted as a region with high fluid content formed by metamorphism associated with the oblique underthrusting of the tarim block beneath the northern tibetan plateau these fluids migrate upwards through the fault system and have formed serpentinized zones in the crust combining these interpretations a structural model compatible with diverse geophysical observations is proposed in which we suggest the competing end member rigid block model and continuum model are reconcilable with the continuum model locally dominant for the study region as evidenced by a thickened crust

contributions of triassic tectonism to build the northern tibetan plateau insights from tectonic evolution of the jinhongshan range central altyn tagh fault system

hydrogeological investigation of antalya basin concerning the future domestic water needs of antalya city turkey a hydrogeological study has been carried out in antalya travertine basin for the future domestic water supply of antalya geological formations that could be used as an aquifer have been identified and a hydrogeological map has been prepared water quality analyses show that groundwater has been and is being contaminated by sewage discharge industrial works and other activities that create an ever expending impact to the only available aquifer something should be done immediately to protect the aquifer from additional degradation

mesozoic cenozoic evolution of the xining minhe and dangchang basins northeastern tibetan plateau magnetostratigraphic and biostratigraphic results 1 accurate stratigraphic ages are crucial to understanding the deformation history of the tibetan plateau prior to and during the indo asian collision efforts to quantify mesozoiccenozoic ages are hindered by limited fossils and a paucity of volcanic horizons and regionally correlative strata magnetostratigraphic and biostratigraphic results from the xining minhe longzhong basin complex and dangchang basin provide an improved chronology of nonmarine basin development over a large region of the northeastern tibetan plateau 34 37 n 101 105 e analyses of 171 magnetostratigraphic levels and 24 palynological assemblages 120 species indicate late jurassic early cretaceous to mid tertiary deposition although magnetic polarity zonation is incomplete independent palynological age control partially restricts possible correlations to the geomagnetic polarity timescale the sediment accumulation record basin provenance structural geology and published thermochronological data support a history of jurassic exhumation late jurassic early cretaceous fault related basin initiation and cretaceous paleogene reduced accumulation these patterns which are compatible with late jurassic early cretaceous extension and cretaceous paleogene postrift thermal subsidence were disrupted at about 40 30 ma when shortening related to the indo asian collision induced localized range uplift vertical axis rotation and amplified subsidence indexterms 1520 geomagnetism and paleomagnetism magnetostratigraphy 8102 tectonophysics continental contractional orogenic belts 9320 information related to geographic region asia 9604 information related to geologic time cenozoic 9609 information related to geologic time mesozoic keywords tectonics magnetostratigraphy tibetan plateau cenozoic mesozoic sedimentary basins

a new hydrogeologically based approach to determining protected areas in drinking water supply reservoirs a case study in the aglasun sub basin burdur turkey this study covers the hydrogeologically based works taking place in the drinking water reservoir drainage basin in the aglasun sub basin to ensure water quality the geological units in the aglasun sub basin are grouped under two units as allochthonous and autochthonous autochthonous units are composed of erenler limestone yazir formation inside reef limestone the aglasun formation seen as flysch and alluvium allochthonous units are composed of akdag limestone and ophiolitic complex autochthonous positioned limestones with their dissolution cavities are classified as karstic aquifers there is no hydraulic relationship between autochthonous positioned limestones and drinking water reservoir allochthonous positioned limestones are classified as karstic aquifers having large number of spring discharges in the studied basin a groundwater vulnerability map has been prepared which is an effective tool in determining the water resource protection areas the drastic method was used when preparing the groundwater vulnerability map the groundwater depth net recharge aquifer type soil media topography vadose zone effect and hydraulic conductivity parameters were used to form thematic maps and were evaluated with the help of arcgis technology the most sensitive areas to groundwater are distinctively the areas covered with alluvium and allochthonous limestone springs discharging from these sensitive areas recharge the stream that connects to the reservoir it is therefore understood that the traditional protection areas determined after the maximum water level are inadequate in protecting the water quality in a drinking water basin in addition to existing protection zones this study suggests hydrogeologically based new protection areas which also include streams flowing into the reservoir

landscape and tectonic evolution of bayin river watershed northeastern qaidam basin northern tibetan plateau implications for the role of river morphology in source analysis and low temperature thermochronology

evaluating the role of preexisting weaknesses and topographic distributions in the indo asian collision by use of a thin shell numerical model thin viscous sheet models have proved to be very useful in exploring the interaction between plate boundary and gravitational forces during continental collision however simplifications of these models e g absence of faults planar geometry of the collision zone limit their use in making specific predictions regarding tectonic evolution such as the role of eastward extrusion along major strike slip faults during the indo asian collision this deficiency is overcome by a thin shell finite element model with faults that can assess the effects of preexisting fault configurations and topographic distributions on velocity fields numerical simulations of a palinspastically restored asia at ca 50 ma suggest that preexisting lithospheric weaknesses favor north south shortening during initial collision whereas preexisting high topography in southern asia promotes eastward extrusion these results underscore the first order importance of initial topography and the distribution of preexisting faults in the outcome of geodynamic modeling

mechanisms of global teleconnections associated with the asian summer monsoon an intermediate model analysis the indian summer monsoon ism and western north pacific summer monsoon wnpsm are two subsystems of the asian summer monsoon and they exhibit different global teleconnection patterns the enhanced ism strengthens the south asian high and mascarene high and the wnpsm excites a meridional tripolar wave train in the northern hemisphere and affects the australian high in the southern hemisphere to understand the dynamics behind these global teleconnections especially the processes responsible for the cross equatorial teleconnection an intermediate model describing a two level troposphere and a steady planetary boundary layer pbl is linearized from the background horizontal wind field the model results indicate that the ism heating located under the strong easterly vertical shear vs and close to the westerly jet in the northern hemisphere can excite a barotropic rossby wave that emanates northwestward and then propagates downstream along the westerly jet since the wnpsm heating is far away from the westerly jet over the north pacific it only excites a weak rossby wave train which cannot explain the meridional tripolar teleconnection associated with the wnpsm it is found that both the ism and wnpsm heating excite strong teleconnections in the southernhemisphere via an advectionmechanism that is the background upper level northerly winds can transport energy across the equator from the northern hemisphere summer monsoon to the southern hemisphere westerly jet in addition the pbl enhances monsoon teleconnections by trapping more energy in the upper troposphere the elevated maximum monsoon heating also reinforces upper level perturbations and enhances the teleconnection pattern

sst forced surface wind variability in the tropical atlantic an empirical model 1 simple dynamical models developed for the tropical pacific surface winds may not be directly applicable in the atlantic in view of the basin s different geometry and size and the potential impact of deep heating from over the adjacent african and south american continents as simple dynamical models generate surface winds from sea surface temperature sst it is worth ascertaining the extent to which monthly surface winds over the tropical 30 s 30 n atlantic are driven by this sector s own sst variations a procedure is developed to separate this internally driven i e by tropical atlantic basin ssts component of the surface wind field from those induced by changes external to this tropical basin our analysis shows the internally driven component to dominate wind variability only within the equatorial 10 s 10 n atlantic in contrast pacific surface winds driven by the tropical pacific basin ssts dominate variability across the tropical pacific the vertical structure of atmospheric diabatic heating linked with the leading modes of internally driven variability in the two basins e g pacific el nino and the atlantic nino is compared to assess the suitability of hypotheses underlying simple dynamical models the potential limitations of these models particularly in the tropical atlantic motivated the development of an empirical model for atlantic surface wind variability the model is based on rotated principal component analysis rpca of the internally driven component of interannual variability in the tropical atlantic basin the empirical model is constructed from rpca analysis of combined sst and surface wind anomalies of individual calendar months from coads data set and outperforms the simple dynamical models the model s performance is also compared to an empirical model based on the singular value decomposition analysis of sst and surface winds

petrology and geochronology of eclogites from the western segment of the altyn tagh northwestern china abstract the eclogites from the western segment of the altyn tagh occur as lens or boundins within quartzofeldspathic gneisses or pelitic gneisses characterized by amphibolite facies parageneses the petrographic features and reaction textures testify to three main metamorphic stages 1 the peak eclogite facies stage p 15 kbar t 665 880 c 2 the granulitic facies stage p 11 14 kbar t 670 800 c and 3 the amphibolite facies stage p 6 3 9 5 kbar t 619 738 c during decompression the trace element rare earth element and sm nd isotopic data suggest that most of the eclogites have protolith features resembling transitional type t type mid ocean ridge basalt morb the well preserved eclogite was selected for sm nd and u pb isotopic dating the sm nd isotopic data yield a whole rock garnet omphacite isochron of 500 10 ma age the u pb isotopic measurement of zircons from the same eclogite shows that the four grain populations are near concordant and are well plotted on concordia giving a weighted mean age of 503 9 5 3 ma the two different geochronological methods yield a similar age which is interpreted as the peak metamorphic age of eclogites and reflects the existence of a mountain root related to continental subduction during early paleozoic moreover based on the comparison with similar rocks in the northern margin of the qaidam basin a displacement of 350 400 km for the altyn tagh fault have been estimated

separation of groundwater flow components in a karstified aquifer using environmental tracers abstract groundwater discharges from the intensively karstified taurus mountains to the mediterranean sea either along the contact zone between the mountains and the travertine plateau the kirkgozler springs 15 m3 s or through the travertine e g the dudenbasi spring 18 m3 s and underneath it unnamed submarine springs unknown discharges in an attempt to identify the hydraulic connections between the various outlet points groundwater was analyzed for stable and radioactive isotopes cfcs and he the upgradient springs belonging to the kirkgozler dudenbasi system were proven to be a mixture of recent and older water on the basis of their low 14c values 12 22 4 pmc their exceptionally high he content 429 991 cc kg and 3he 4he r ra ratios 1 471 2 602 and their measurable 3h and cfc contents 1 9 5 9 tu and 0 84 to 3 27 pmoles kg respectively the older component probably contains an even lower amount of modern c however the undersaturation of the mixture with respect to calcite its high co2 content up to 83 mg l and its enriched 13c values 2 2 to 4 1 suggest intensive water rock interactions which would contribute 14c devoid bicarbonates to the solution downgradient springs discharging along the mediterranean coast contain groundwater contributions from higher altitudes as evidenced by their depleted 18o and d composition with respect to the local precipitation however a larger portion of the recent water component could be contributed from direct precipitation on the travertine this larger component is reflected in the increased 3h 3 4 to 8 4 tu and 14c 32 7 63 6 pmc contents atmospheric he 43 82 pmoles kg r ra values 1 006 1 198 and cfc contamination of the water

jurassic to cenozoic exhumation history of the altyn tagh range northwest china constrained by 40ar 39ar and apatite fission track thermochronology

cenozoic vertical axis rotation of the altyn tagh fault system paleomagnetic declination data were collected from cenozoic strata of the southern rim of the tarim basin to address whether the altyn tagh fault has undergone significant rotation during the indian asian collision results from the eastern and central altyn tagh fault zone suggest that it has undergone no significant rotation since the oligocene this implies that the boundary between the tarim and tibet has remained relatively stationary during most of the cenozoic in contrast declination data from the western kunlun shan on the eastern limb of the pamir orocline where the karakax segment of the altyn tagh fault system terminates suggest that the range has undergone clockwise rotations of between 19 3 8 6 and 27 8 5 8 such rotation is in mirror image with the documented counterclockwise rotation of 20 50 in the western pamir orocline and implies relatively small displacements on the karakorum fault our results also suggest that the karakax fault may have formed as an accommodation zone between the western kunlun shan and the karakorum mountains

pattern and kinematic polarity of late mesozoic extension in continental ne asia perspectives from metamorphic core complexes 1 late mesozoic extension in ne asia resulted in the development of a large extensional province metamorphic core complexes mccs are the major features in this province and have 40ar 39ar ages of 130 110 ma for the mylonites and u pb zircon ages of 150 110 ma for the integral granitic intrusions based on this and previous studies this paper summarizes major characteristics of these mccs and recognizes a regional kinematic shear sense most mccs in the transbaikalia region sino mongolia border tract and the northwest central portion of the north china craton ncc show a top to the southeast se shear whereas those in the eastern and southern ncc locally underwent top to the northwest nw shear the three largest basins songliao huabei and ordos in north china are located in the transitional zone between domains of opposing shear sense we interpret the extension in the transbaikalia sino mongolia tract and northwestern part of the ncc to reflect late orogenic collapse of thickened crust following middle late jurassic collision along the okhotsk suture the southeastward extension is probably controlled by crustal scale top to the se tangential shear the transition from contraction to extension is marked by detachment faults that nucleated as extensional crenulation cleavage ecc i e c in sub horizontal ductile shear zones late in orogenic crustal thickening the combined effect of gravitational loading and thermal uplifting is considered to be the origin of the late or post orogenic collapse the top to the nw extension in the ne of the ncc might reflect antithetic sub extensional zones or mesozoic back arc extension as a far field effect of cretaceous pacific plate subduction

anomalous tropical ocean circulation associated with la nina modoki 1 el nino modoki is a variant of el nino characterized by warming around the dateline flanked by anomalous cooling in the east and west however the opposite phase la nina modoki has received little attention because the prominent cooling of sea surface temperature sst during major la nina events is observed in the central pacific and thus it is difficult to define the two different types of cold events from the sst anomaly pattern here we demonstrate that cold events in 2000 and 2008 can be clearly distinguished from traditional la nina events using surface currents derived from satellite observations during 2000 and 2008 anomalous zonal currents in the equatorial pacific demonstrate divergence with westward currents west of the dateline and eastward currents east of it these currents are opposite to the circulation pattern during the 2004 el nino modoki event an empirical orthogonal function eof analysis of surface currents for the period 1993 2009 shows a circulation anomaly pattern similar to that in 2000 2004 and 2008 in the second eof the first eof is consistent with traditional el nino la nina events and does not exhibit a current reversal along the equator our results also indicate that strong cyclonic anticyclonic circulation anomalies occur in the tropical western pacific around 5 n 15 n during the 2004 2000 and 2008 el nino la nina modoki events and during the strong traditional el nino la nina events of 1997 1998 these circulation anomalies are related to an sst gradient in the western and central pacific

tectonic history of the altyn tagh fault system in northern tibet inferred from cenozoic sedimentation the active left slip altyn tagh fault defines the northern edge of the tibetan plateau to determine its deformation history we conducted integrated research on cenozoic stratigraphic sections in the southern part of the tarim basin fission track ages of detrital apatites existing biostratigraphic data and magnetostratigraphic analysis were used to establish chronostratigraphy whereas composition of sandstone and coarse clastic sedimentary rocks was used to determine the unroofing history of the source region much of the detrital grains in our measured sections can be correlated with uplifted sides of major thrusts or transpressional faults implying a temporal link between sedimentation and deformation the results of our studies together with existing stratigraphic data from the qaidam basin and the hexi corridor suggest that crustal thickening in northern tibet began prior to 46 ma for the western kunlun shan thrust belt at ca 49 ma for the qimen tagh and north qaidam thrust systems bounding the north and south margins of the qaidam basin and prior to ca 33 ma for the nan shan thrust belt these ages suggest that deformation front reached northern tibet only 10 5 m y after the initial collision of india with asia at 65 55 ma because the aforementioned thrust systems are either termination structures or branching faults of the altyn tagh left slip system the altyn tagh fault must have been active since ca 49 ma the altyn tagh range between the tarim basin and the altyn tagh fault has been a long lived topographic high since at least the early oligocene or possibly late eocene this range has shed sediments into both the tarim and qaidam basins while being offset by the altyn tagh fault its continuous motion has made the range act as a sliding door which eventually closed the outlets of westward flowing drainages in the qaidam basin this process has caused large amounts of oligocene miocene sediments to be trapped in the qaidam basin the estimated total slip of 470 70 km and the initiation age of 49 ma yield an average slip rate along the altyn tagh fault of 9 2 mm yr remarkably similar to the rates determined by gps global positioning system surveys this result implies that geologic deformation rates are steady state over millions of years during continental collision

simple solutions for the summer shallow atmospheric circulation over north africa the spring to summer shallow atmospheric circulation over north africa is driven by two desert heat lows dhls one over sahara shl and one over arabia ahl with cyclones embedded in the convective layer capped by mid tropospheric anticyclones the aim of this work is to produce a minimal theoretical framework for these dynamical features in terms of kelvin mixed and planetary mode solutions to a two layer matsuno gill model with a lower rayleigh frictional layer dynamically coupled to an almost frictionless upper layer results show that a dhl drives a walker like cell with rising air over the low and subsiding air to its west with the lower level cyclone to the east of the mid tropospheric anticyclone the latter being bounded to the south west by an unstable easterly jet these features related to frictional differences between the two layers are enhanced by ambient easterly winds in spring the stronger shl drives a cell with rising air over west africa and subsiding over the atlantic the weaker ahl drives a cell with rising air over arabia and subsiding over east africa in summer the stronger ahl drives a cell with rising air over arabia and subsiding over libya and the weaker shl drives a cell with rising air over west sahara and subsiding over the atlantic the concurrent contributions of easterly winds monsoonal low level convergence and seasonal airborne dust warming strengthen the shl making its winds stronger than those of the ahl in addition a third order expansion of the coriolis parameter strengthens the zonal winds and weakens the meridional winds these contributors strengthen anticyclones over the east mediterranean and to the west of gibraltar the ability of the model in representing the main features of the north african atmospheric circulations suggests a potential for better understanding climate dynamics in connected regions mediterranean tropical atlantic

blueschist bearing metamorphic core complexes in the qiangtang block reveal deep crustal structure of northern tibet a 500 km long belt of metamorphic exposures in the qiangtang block provides an opportunity to study the internal structure of northern tibetan crust metamorphic rocks exposed at two widely separated areas along this belt consist of blueschist bearing melange and are bounded by late triassic early jurassic domal low angle normal faults we propose that this melange was underplated to the qiangtang block and was subsequently exhumed by detachment faulting both the underplating and the exhumation occurred during early mesozoic southward subduction of oceanic lithosphere along the jinsha suture this model predicts that the deeper crust of much of northern tibet consists of accretionary melange in contrast to the continental crystalline crust of southern tibet and may account for north south variations of cenozoic tectonism in tibet

paleocene eocene syncontractional sedimentation in narrow lacustrine dominated basins of east central tibet sedimentologic stratigraphic compositional and structural data from four elongate basins 30 km long in the nangqian yushu region of east central tibet near the headwaters of the mekong and yangtze rivers indicate nonmarine sedimentation synchronous with paleocene eocene northeast southwest shortening sedimentation in the nangqian niuguoda xialaxiu and shanglaxiu basins involved 1 mud and carbonate accumulation in offshore to nearshore lacustrine environments and 2 gravel and sand deposition in fan delta to alluvial fan environments localized near basin margins growth strata in both fine and coarse grained deposits primarily in upper levels of basin fill provide evidence for sedimentation contemporaneous with motion on fold thrust structures provenance data collected from 25 measured stratigraphic sections including 1500 paleocurrent measurements and 150 conglomerate compositional analyses show that each basin was fed sediment from several directions by proximal source areas composed of carboniferous triassic rocks the source area proximity and a stratigraphic variability among the basins suggest that each basin evolved independently and was filled by sediment derived from relatively small drainage networks 103 km2 age control for basin fill is based on paleogene fossils 38 37 ma 40ar 39ar ages from volcanic rocks interbedded with uppermost strata of the nangqian basin and 51 49 ma 40ar 39ar ages from igneous rocks that intrude and unconformably overlie strata of the shanglaxiu basin strata containing middle cretaceous palynomorph and ostracod assemblages are present only locally in the lowermost part of the nangqian basin although the tectonic setting for cretaceous sedimentation is unclear early tertiary basin development was controlled by thin skinned fold thrust deformation we interpret the narrow widths of paleocene eocene basins to be a result of thrust spacing which in turn may have been controlled by the depth to the decollement 5 km deep according to our balanced cross section from which imbricate thrusts ramped up through the carboniferous triassic section sedimentologic and provenance evidence for internal drainage limited unroofing and relatively low average sediment accumulation rates in these syncontractional plateau interior basins indicates generally small drainage systems short main stem rivers shallow regional slopes and limited denudation in east central tibet during early tertiary time such geomorphic conditions which are similar to the modern low relief interior of the tibetan plateau suggest that the deeply incised mekong and yangtze rivers of eastern tibet were not established until after the termination of paleogene basin development in the region

provenance and paleogeography of the jurassic northwestern qaidam basin nw china evidence from sedimentary records and detrital zircon geochronology abstract the qaidam basin is the largest meso cenozoic petroliferous basin on the northeastern tibetan plateau and was situated at the northern margin of the eastern tethys during the mesozoic jurassic strata are the main source rocks and reservoirs in the northern and western segments of this basin however due to exceptionally thick overlying cenozoic strata intensive post depositional modification and limited deep exploration data several crucial problems regarding this basin remain controversial including provenance supply original sedimentary extent and overall properties in the jurassic period this hinders further understanding of regional geological evolution and hydrocarbon exploration this paper focuses on comparison of residual jurassic strata in the northwestern qaidam basin the adjacent saishiteng mountains and the suganhu area to the north based on sedimentology and provenance analyses detrital zircon geochronology was employed to examine the provenance of jurassic sediments in different areas and to reconstruct their dispersal patterns results show that the lower jurassic deposits are characterized by near provenance and rapid facies shift fan deltas braided river deltas and lacustrine deposits are commonly developed the lower jurassic source area was mainly located in the south altyn tagh mountains sedimentary extent and depocenters in the middle and late jurassic transferred northwards to the current piedmont of the saishiteng and south qilian mountains the residual jurassic in the saishiteng mountains is similar and comparable with coeval strata in the suganhu area as well as the inner qaidam basin detrital zircon ages indicate multiple provenances in the middle jurassic of which the southern qilian mountains are the most important in the middle jurassic deposition occurred across large areas of the saishiteng mountains which belonged to the same basin as the inner qaidam basin and the suganhu areas a series of small scale continental rift basins developed in the western part of northwestern qaidam in the early jurassic and then developed into a larger depression from the late early jurassic to the late jurassic post collision extension was conducive to the development of rift basins in the early jurassic subduction of the northern mongolian okhotsk and southern central tethys ocean interactively led to an extensional tectonic setting and the development of a depression basin in late early to middle jurassic the continuous northward compression of the qiangtang block mainly resulted in a compressive tectonic setting in the late jurassic

basin analysis of the jurassic lower cretaceous southwest tarim basin northwest china the jurassic through cretaceous southwest tarim basin northwest china contains more than 6 km of fluvial and lacustrine strata deposited in a foreland setting during the successive collisions with eurasia of the changtang block during late triassic early jurassic time and with the mega lhasa block during late jurassic early cretaceous time this tectonism is chronologically linked with the creation of a narrow lower middle jurassic transtensional basin with thick sedimentary infill succeeded by a broader upper jurassic lower cretaceous compressional basin with thinner sedimentary infill the older basin formed between a north northwest striking dextral fault on the eastern side of the southwest tarim basin in the tian shan and a postulated strike slip or normal fault on the western margin of the basin along the kunlun shan the former fault is now the talas ferghana fault the latter may be a predecessor to the main pamir thrust subsidence analysis of the thickest sedimentary section suggests thermal subsidence interpreted as the result of transtension between the two basin bounding faults the younger basin extends farther east and west and does not preserve evidence of activity along the talas ferghana fault the change in basin style between these two episodes of basin development likely reflects either a small counterclockwise rotation of basin bounding structures during the first episode or a small clockwise rotation of the maximum compressive stress between the two episodes

the ereendavaa range north eastern mongolia an additional argument for mesozoic extension throughout eastern asia mesozoic rift basins locally bounding metamorphic core complexes have been recognized in transbaikalia and northern china numerous basement outcrops located between these two regions in eastern mongolia are considered as pre palaeozoic in age one of these the ereendavaa range appears as a gneissic core marked by amphibolite facies metamorphic conditions the range is overlain to the nw by the unmetamorphosed mesozoic onon basin below the basin the upper part of the range consists of a gently nw dipping shear zone associated with top to the nw motion the structural pattern is consistent with syn extensional exhumation of the range preliminary geochronological data indicate that the shear zone is late jurassic to early cretaceous in age coeval with the onon basin these new data from eastern mongolia constitute a link between transbaikalia and northern china indicating that nw se extensional mesozoic tectonics occurred throughout the entire region

the role of base level watershed attribute and sediment accumulation in the landscape and tectonic evolution of the circum tibetan plateau basin and orogen system abstract the india asia collision produces the outstanding circum tibetan plateau basin and orogen system in this study we systemically analyze and discuss the relationship between isostasy base level and sedimentary process in the landscape and tectonic evolution of the circum tibetan plateau basin and orogen system considering of isostatic effects the basin filling processes can individually lead to the subsidence of the sedimentary floor bringing numerous geological implications on the conditions of ideal geological models and isostatic equilibrium the sedimentary surface of the exorheic basins with strong hydrodynamic condition is constrained by sea level through the river longitudinal profile and crustal thinning processes of the non flexural exorheic basins can be sculpted by sedimentary records when the source supply keeps sufficient long term and large scale rising and dropping of the sea level can influence the subsidence rate of the extensional exorheic basins on the other hand the endorheic basins are of individual base levels and isostatic effects of the sedimentary loading can lead to the uplift of the sedimentary surface in this situation the uplift process of the endorheic basins can be estimated by sedimentary records regional reorganization of river watersheds can lead to a series of geological impacts such as the changing of base level the redistribution of loose deposits beginning or end of depositional discontinuity and fluctuation of the sedimentary floor thus the geological implications for the changing of the sedimentary rates and the depositional discontinuity should be carefully identified in the landscape and tectonic evolution of the circum tibetan plateau basin and orogen system

jurassic tectonostratigraphic evolution of the junggar basin nw china a record of mesozoic intraplate deformation in central asia mesozoic basins in northwest china provide important records for investigating relationships between intraplate deformation in central asia and tectonic processes at asian boundaries the present study using well seismic outcrop and thermochronology data in the junggar basin and neighboring areas describes the main features of jurassic strata in the basin analyzes the jurassic evolution of the basin and neighboring mountain belts and discusses possible mechanisms of jurassic intraplate deformation in central asia during the early middle jurassic episodic uplift of surrounding mountain belts kept the junggar basin a contractional closed basin and alluvial fan fluvial delta and lacustrine depositional environments successively developed from surrounding ranges to the central basin during the late jurassic the western and central parts of the basin were folded and uplifted and deposition migrated mainly to the eastern basin during the latest jurassic earliest cretaceous pre cretaceous strata in the eastern and northeastern junggar basin were folded and uplifted and coarse grained sediments were transported from surrounding uplifts to the central basin we suggest that jurassic episodic deformation events in the junggar basin and other areas of central asia are related to the qiangtang collision during the late triassic early jurassic the closure of the western mongol okhotsk ocean at the early middle jurassic boundary a collision of a microcontinent in the pamir with the southern asian margin during the late middle jurassic early late jurassic the collision of the kolyma omolon block with siberia at the end of the jurassic and the subsequent closure of the eastern mongol okhotsk ocean during the latest jurassic earliest cretaceous

residence time distribution in the kirkgoz karst springs antalya turkey as a tool for contamination vulnerability assessment lumped parameter modeling of environmental tracer tritium cfcs and tritiogenic helium 3 transport in the kirkgoz karst springs antalya turkey appears to be a useful tool for assessing the vulnerability to contamination based on tritium observations between 1963 and 2000 the springs revealed a mean residence time mrt of 120 years this suggests an active transport volume of 71 billion cubic meters for the aquifer a value that is coherent with the estimated void volume of karst aquifer based on the mass of associated travertine deposits the cfc 11 and cfc 12 mrts are in agreement with tritium based mrt after correcting for excess air effect excess crustal and mantle helium flux hindered the use of tritiogenic helium 3 as a potential tracer the residence time distribution rtd indicates a groundwater transport system that is fed by recharges extending back to past several hundred years this wide rtd suggests that any recent contamination that may have entered the system could progress slowly within the entire aquifer but would be unnoticed in the early period because of the dilution effect of uncontaminated past recharge waters once the contamination is recognized it may last for many centuries ahead even if the contamination practice is stopped thus control of contaminant release to aquifer and monitoring of contaminant level in kirkgoz springs is an immediate task for the associated public health authorities

did the indo asian collision alone create the tibetan plateau it is widely believed that the tibetan plateau is a late cenozoic feature produced by the indo asian collision however because tibet was the locus of continental accretion and subduction throughout the mesozoic crustal thickening during that time may also have contributed to growth of the plateau this portion of the geologic history was investigated in a traverse through the central lhasa block southern tibet together with earlier studies our mapping and geochronological results show that the lhasa block underwent little north south shortening during the cenozoic rather our mapping shows that 60 crustal shortening perhaps due to the collision between the lhasa and qiangtang blocks occurred during the early cretaceous this observation implies that a significant portion of southern tibet was raised to perhaps 3 4 km elevation prior to the indo asian collision

ore genesis and fluid evolution of the kaladawan south zn pb cu ore field eastern altyn mountains nw china evidence from fluid inclusions h o isotopes and geochronology abstract the newly discovered kaladawan south zn pb cu orefield in eastern altyn mountains is composed of five zn pb cu deposits with the largest one containing 414 4 thousand tonnes kt zn 265 2 kt pb and 149 2 kt cu stratiform lenticular orebodies are hosted by the ordovician volcanic sedimentary sequences subjected to greenschist facies metamorphism two major ore forming stages with significant cross cutting relationship are identified at kaladawan south stage i of the earlier massive banded disseminated barite rich sulfide ores and stage ii of the later polymetallic sulfide quartz veins with economically less importance fluid inclusions fis locked in quartz of stage i massive sulfide ores are homogenized completely at 226 354 c with calculated seawater like salinities of 2 7 4 2 wt nacl equiv these characteristics of ore forming fluids coupled with ore textures of typical vms deposits are interpreted to be originated from the modified seawater by sea floor volcanic hydrothermal activities in compared the stage ii fis yielded lower homogenization temperatures ranging 251 c 357 c with higher salinities of 0 8 14 4 wt nacl equiv laser raman analyses identified large amounts of co 2 ch 4 n 2 in the hydrothermal fluids of stage ii the 18 o h2o values 0 5 5 7 and d h2o values of 68 1 to 32 3 of stage ii quartz are plotted in the range of metamorphic fluids in the d o isotopic diagram which indicating that the co 2 rich and mesothermal fluids are metamorphic derived the phlogopite paragenetic in the stage ii polymetallic vein yielded a 40 ar 39 ar plateau age of 435 4 3 9 ma similar to the age of the metamorphic muscovite 451 0 4 1 ma from the ore hosting schist based on the ore deposit geology mineral assemblages and fluid geochemistry the kaladawan south zn pb cu mineralization is attributed to be an ordovician vms type deposit overprinted by the silurian metamorphic fluids

geodynamics of the western part of the mongolia okhotsk collisional belt trans baikal region russia and mongolia abstract after the western edge of the mongolian microcontinent joined the siberian continent in the region of central mongolia in the earliest permian these two continental blocks remained turned at an angle of about 120 with respect to each other and separated on greater extent of their present day boundary by an enormous gulf of the paleopacific called the mongolia okhotsk ocean closure of this ocean at the early middle jurassic boundary led to the complete collision of siberia and mongolia which by then had already become part of the mongolia north china continent this main collisional episode which lasted through the middle and late jurassic involved thrusting folding and magmatism and produced the mongolia okhotsk belt the onon island arc which was located in the mongolia okhotsk ocean was squeezed between the two major continents inasmuch as the third element the island arc was involved in the collision it is reasonable to distinguish two branches of the mongolia okhotsk suture these branches control the spatial distribution of gold mineralization in the trans baikal region on the southeastern periphery of siberia the crust thickened considerably after the collision and a plateau like uplift formed in the early cretaceous when compression ceased the collisional uplift collapsed and the thrusts were transformed into low angle normal faults the motions on which were responsible for the formation of rift basins and exhumation of metamorphic core complexes

a possible middle paleozoic suture in the altyn tagh nw china preliminary 40ar 39ar thermochronologic results from two transects across the altyn tagh at range allow new interpretations for the genesis of the range and provide constraints for its subsequent displacement recent reports of middle to upper ordovician pillow lavas in the ne portion of the range as well as the first reports of high pressure metamorphic rocks within the range are interpreted as the remnants of a lower paleozoic ocean subducted within the at muscovite and biotite ages from schist gneiss and granodiorite document a significant metamorphic and intrusive event throughout the range at 435 20 ma this fabric is crosscut by undeformed postorogenic microgranite plutons dated at 383 7 ma by muscovite these data suggest that an ocean basin closed after the early silurian and prior to the middle devonian forming the herein named lapeiquan suture the lack of similary aged plutons to the north and the suggestion of a synchronous arc to the south implies that subduction was south dipping present geography if the altyn tagh contains a middle paleozoic suture lateral continuations should be identifiable possibilities to the west include the kudi suture in the western kunlun shan comparisons of lithologies and radiometric data reveal significant similarities between the kudi suture and the altyn tagh suggesting that the at originated as part of the same middle paleozoic orogenic belt reconstruction of the paleozoic structure of northern tibet is complicated by cenozoic deformation particularly along the altyn tagh fault although this could be used as a measure of the finite post devonian deformation a more thorough understanding of paleozoic geodynamics is a prerequisite to unraveling subsequent displacements

origin and interactions of fluids circulating over the amik basin hatay turkey and relationships with the hydrologic geologic and tectonic settings abstract we investigated the geochemical features of the fluids circulating over the amik basin se turkey syria border which is crossed by the northern extension of the dsf dead sea fault and represents the boundary area of three tectonic plates anatolian arabian and african plates we collected 34 water samples thermal and cold from natural springs and boreholes as well as 8 gas samples bubbling and gas seepage besides the gases dissolved in the sampled waters the results show that the dissolved gas phase is a mixture of shallow atmospheric and deep components either of mantle and crustal origin coherently the sampled waters are variable mixtures of shallow and deep ground waters the latter being characterised by higher salinity and longer residence times the deep groundwaters from boreholes deeper than 1000 m have a ch 4 dominated dissolved gas phase related to the presence of hydrocarbon reservoirs the very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the african plate as well as basalts located to the north and east on the arabic plate the diffuse presence of co 2 enriched gases although diluted by the huge groundwater circulation testifies a regional degassing activity fluids circulating over the ophiolitic block are marked by h 2 dominated gases with abiogenic methane and high ph waters the measured 3 he 4 he isotopic ratios display contributions from both crustal and mantle derived sources over both sides of the dsf although the serpentinization process is generally independent from mantle type contribution the recorded helium isotopic ratios highlight variable contents of mantle derived fluids due to the absence of recent volcanism over the western side of the basin african plate we argue that co 2 rich volatiles carrying mantle type helium and enriched in heavy carbon are degassed by deep rooted regional faults rather than from volcanic sources

occurrence age and implications of the yagan onch hayrhan metamorphic core complex southern mongolia mylonitic rocks associated with the south dipping detachment fault of the yagan onch hayrhan metamorphic core complex in southernmost mongolia indicate subhorizontal south southeast directed extension in the early cretaceous synkinematic biotites give 40 ar 39 ar ages of 129 to 126 ma the yagan onch hayrhan core complex demonstrates that late mesozoic localized high strain extension recently recognized in other parts of eastern asia also occurred in mongolia the presence of mesozoic metamorphism at onch hayrhan previously presumed to be precambrian brings into question the existence of the south gobi microcontinent

tertiary structural evolution of the gangdese thrust system southeastern tibet structural and thermochronological investigations of southern tibet xizang suggest that intracontinental thrusting has been the dominant cause for formation of thickened crust in the southernmost tibetan plateau since late oligocene two thrust systems are documented in this study the north dipping gangdese system gts and the younger south dipping renbu zedong system rzt west of lhasa the gangdese thrust juxtaposes the late cretaceous forearc basin deposits of the lhasa block the xigaze group over the tethyan sedimentary rocks of the indian plate whereas east of lhasa the fault juxtaposes the late cretaceous eocene andean type arc the gangdese batholith over tethyan sedimentary rocks near zedong 150 km southeast of lhasa the gangdese thrust is marked by a 200 m thick mylonitic shear zone that consists of deformed granite and metasedimentary rocks a major south dipping backthrust in the hanging wall of the gangdese thrust puts the xigaze group over tertiary conglomerates and the gangdese plutonics north of xigaze and west of lhasa a lower age bound for the gangdese thrust of 18 3 0 5 ma is given by crosscutting relationships the timing of slip on the gangdese thrust is estimated to be 27 23 ma from 40 ar 39 ar thermochronology and a displacement of at least 46 9 km is indicated near zedong the age of the gangdese thrust gt is consistent with an upper age limit of 24 ma for the initiation of movement on the main central thrust in places the younger renbu zedong fault is thrust over the trace of the gt obscuring its exposure the rzt appears to have been active at circa 18 ma but had ceased movement by 8 1 ma the suture between india and asia has been complexly modified by development of the gts rzt and locally strike slip and normal fault systems

evolution of the minle and chaoshui basins china implications for mesozoic strike slip basin formation in central asia the minle and chaoshui basins of northern china are pull apart basins that originated during jurassic to early cretaceous strike slip and extensional deformation in the western north china block alashan and the region to its southwest known as the hexi corridor the basins are separated by the longshou shan which has been a positive topographic feature since jurassic time lower cretaceous successions in the minle and chaoshui basins display similar rift related fining upward motifs these comprise alluvial conglomerates and sandstones that pass upward into lacustrine mudrocks followed by a final fine grained alluvial phase with extensive paleosol development the upper part of each succession includes a second lacustrine interval which is related either to a short lived humid climatic period or downstream damming of the exit for the fluvial systems of both basins north south trending normal faults and rare synsedimentary rotation and slump structures affect the basin fills the minle and chaoshui basins are only two of a series of late jurassic early cretaceous strike slip related basins in this region that nucleated on three basement blocks tarim qilian shan and alashan all of the basins are characterized by a nonmarine alluvial lacustrine fill controlled by a combination of strike slip and normal faults from an analysis of the distribution orientation and motion sense of subsurface and exposed faults we conclude that three types of strike slip related basins are present pull apart basins minle huahai jinta chaoshui transtensional basins southwest badanjilin northern wuwei and a third type that developed between divergent strike slip faults of opposing motion senses we term this type extrusion fault wedge basins jiuquan bayanhaote western wuwei the cause of late jurassic to early cretaceous strike slip and extension in this region is interpreted to be the lhasa block asia collision compression arising from this event is speculated to have caused eastward extrusion of the crust of the hexi corridor and alashan deformation was accommodated by a 25 counterclockwise rotation of the alashan with respect to the remainder of the north china block thrusting occurred in the intervening helan shan the extension in the hexi corridor occurred at the same time as vast foreland basins formed to the west tarim and east ordos and while extension affected much of eastern mongolia and northeastern china

jurassic early cenozoic tectonic inversion in the qilian shan and qaidam basin north tibet new insight from seismic reflection isopach mapping and drill core data

interhemispheric influence of indo pacific convection oscillation on southern hemisphere rainfall through southward propagation of rossby waves tropical indo western pacific convection anomalies influence atmospheric circulation impacting climate far beyond the tropics here we present observational and modelling evidence for an interhemispheric effect of the boreal summer june august indo pacific convection oscillation ipco which is characterized by a zonal seesaw pattern between the north indian ocean nio and the western north pacific wnp it is found that the ipco is significantly correlated with simultaneous rainfall over many parts of the southern hemisphere sh including western australia and western brazil these interhemispheric connections in rainfall remain significant when then el nino southern oscillation the indian ocean dipole and the sh annular mode related signals are excluded simultaneously which may help to improve the sh seasonal predictions the physical mechanism that underlies this interhemispheric connection is investigated using observations rossby wave diagnostics and a series of atmospheric model experiments results suggest that convective heating anomalies associated with the ipco excite two distinct southward propagating equivalent barotropic wave trains that propagate into the extratropics in the sh the south africa mid latitudes wave train excited by the heat sink over the nio and the maritime continent subtropical australia wave train excited by the heat source over the wnp we further demonstrate that upper tropospheric northerlies over tropical africa and the indian ocean are responsible for the southward propagation of stationary rossby waves across the easterlies these equivalent barotropic waves then modulate the moisture transport baroclinicity and mid latitude storminess and thus affect rainfall anomalies in the sh the new wave train patterns provide novel insight into the teleconnection pathways of convective heating over the tropical indian ocean and western pacific

sedimentary record and tectonic implications of mesozoic rifting in southeast mongolia the east gobi basin of mongolia is a poorly described late jurassic early cretaceous extensional province that holds great importance for reconstructions of mesozoic tectonics and paleogeography of eastern asia extension is especially well recorded in the structure and stratigraphy of the unegt and zuunbayan subbasins southwest of saynshand mongolia where outcrop and subsurface relationships permit recognition of prerift synrift and postrift mesozoic stratigraphic megasequences within the synrift megasequence three sequences developed in response to climatic and rift related structural controls on sedimentation where best exposed along the northern margin of the unegt subbasin each of the synrift sequences is bounded by unconformities and generally fines upward from basal alluvial and fluvial conglomerate to fluvial and lacustrine sandstone and mudstone resedimented ashes and basalt flows punctuate the synrift megasequence rifting began in the unegt subbasin prior to 155 ma with coarse alluvial filling of local fault depressions subsidence generally outstripped sediment supply and fresh to saline lacustrine environments expanding southward with time dominated the unegt zuunbayan landscape for much of latest jurassic early cretaceous time episodic faulting and volcanism characterized the basin system for the balance of the early cretaceous a brief period of compressional and or transpressional basin inversion occurred at the end of the early cretaceous prior to deposition of a widespread upper cretaceous overlap sequence the driver s of late jurassic early cretaceous extension remain uncertain because southeast mongolia occupied an intraplate position by the beginning of the cretaceous extension in the east gobi basin was coeval with collapse and extension of early mesozoic contractional orogenic belts along the northern and southern borders of mongolia and probably was a linked phenomenon strike slip faulting associated with collisions on the southern asian and mongol okhotsk margins likely also played a role in late mesozoic deformation of the east gobi region perhaps partitioning the gobi from apparently coeval large magnitude contractional deformation in the yinshan yanshan orogenic belt south of the study area in inner mongolia

intracrustal detachment within zones of continental deformation geologic mapping of active to recently active geologic structures in panamint valley western united states and in the haiyuan region and northern tibetan plateau china suggests detachment in the middle and lower crust on a scale of tens of kilometres to at least several hundred kilometres detachment occurs similarly in predominantly extensional panamint valley and in predominantly compressional china environments it involves structures with displacements of more than 10 km and displacement rates of more than 3 mm yr perhaps more than 10 mm yr the steeply dipping strike slip faults present in all three areas hunter mountain fault haiyuan fault and altyn tagh fault zone terminate in zones of extension or compression and geometric relations indicate that all structures including strike slip faults are thin skinned and restricted to the upper crust in panamint valley and in the haiyuan region deformation within these systems can be reconstructed in three dimensions displacement on the strike slip faults is absorbed by extension or compression occurring at the termination of the faults so strike slip displacement is roughly equal to and in the same direction as shortening or extension we propose that left slip on the altyn tagh fault zone in northern tibet is similarly absorbed by shortening southeast of the fault zone within the qaidam basin and the nan shan

detrital zircon geochronology of the northeastern tibetan plateau u pb geochronologic analyses have been conducted on 413 detrital zircon grains collected from 16 samples in the altun shan nan shan and qilian shan the samples come primarily from quartz arenites and metaturbidites of middle to late proterozoic age and from feldspathic and volcanic clast rich sandstones of early paleozoic age zircon grains in proterozoic strata resting on tarim basement yielded mainly 2 0 1 9 ga ages whereas proterozoic strata of the qaidam and qilian terranes yielded mainly ca 930 820 ma and ca 1 9 1 1 ga ages the younger grains were apparently shed from local igneous rocks whereas the grains older than 1 1 ga were shed from an undetermined continental source grains in the lower paleozoic strata are mainly ca 500 430 ma and were shed from nearby plutonic and possibly volcanic rocks that formed in a magmatic arc setting our detrital zircon ages are consistent with a model first proposed by e r sobel and n arnaud in which early paleozoic magmatism occurred within a single northeast facing magmatic arc that was constructed across an assemblage of middle to late proterozoic accretionary complexes remnants of magmatic arcs and shallow marine strata this arc system was accreted to the tarim and sino korean cratons during silurian devonian time the resulting suture has been reactivated as tertiary thrust faults that currently define the structural and topographic margin of the tibetan plateau our data also provide two new estimates for the offset along the eastern altyn tagh fault a belt of middle proterozoic shallow marine strata is offset by 400 km whereas a belt of 490 480 ma magmatic arc rocks is offset by 370 km these values are generally similar to the 350 400 km offset reported in most previous studies

two phases of mesozoic north south extension in the eastern altyn tagh range northern tibetan plateau 1 the 300 km long east striking lapeiquan fault lies in the eastern altyn tagh range along the northern margin of the tibetan plateau and was interpreted as a north dipping thrust in early studies however our mapping shows that the fault is a south dipping normal fault juxtaposing archean proterozoic gneisses beneath an early paleozoic volcanic and sedimentary sequence its dip angle varies from 30 to 60 the central fault segment is expressed as a 30 50 m thick ductile shear zone with well developed mylonitic fabrics and stretching mineral lineations where the eastern and western segments are characterized by cataclastic deformation kinematic indicators such as asymmetric boudinage asymmetric folds and minor brittle and ductile faults within the fault zone consistently indicate a top south normal slip sense of shear the age of the lapeiquan fault is constrained by two types of information first a sequence of early middle jurassic sediments is locally present in the hanging wall of the lapeiquan fault the clasts of the jurassic strata particularly the stromatolite bearing cherty limestone and purple quartzite can be correlated uniquely with those in the footwall of the fault we interpret that the early middle jurassic strata were deposited in an extensional basin related to motion along the lapeiquan fault second 40ar 39ar thermochronologic analyses indicate two prominent cooling events in the lapeiquan footwall the older event occurred in the latest triassic earliest jurassic between 220 and 187 ma while the younger event occurred in the latest early cretaceous at 100 ma because the 220 187 ma cooling ages are widespread in the lapeiquan footwall we suggest it to represent the main stage of faulting we interpreted the younger phase of fault motion at 100 ma to have been related to fault reactivation the deformation was aided by motion along the south dipping qiashikan normal fault that merges with the eastern lapeiqaun fault from the regional tectonic setting it appears that mesozoic extension in northern tibet to have occurred in a back arc setting during northward subduction of the tethyan oceanic plate the findings of mesozoic extensional structures in northern tibet suggest that compressive stress induced by collision of the qiangtang and lhasa terranes with asia was not transmitted beyond northern tibet this in turn implies that the popularly inferred contractional setting for mesozoic evolution of the tian shan north of tibet needs a reevaluation based on a combination of both structural and sedimentological observations

the relationship between kestel polje system and the antalya tufa plateau their morphotectonic evolution in isparta angle antalya turkey abstract this paper focuses on the relation between two significant geomorphic features of the western taurides the antalya tufa plateau and the structural kestel polje system revealing morphotectonic records of the formation and evolution of karst hydrology between the two features data were obtained by detailed mapping of faults rocks and geomorphic features the evolutionary history of the area begins with a nearly e w trending drainage system which flowed on the erosional surfaces formed during late langhian early messinian under the compressional tectonic regime the running waters comprising the major drainage system incised the valleys during the messinian salinity crisis and partly in the pliocene by over 200 m depth across the study area from the beginning of the quaternary a tensional tectonic regime became prominent and a series of graben horst structures were formed the kestel polje system consisting of five sub poljes developed within the graben structures which emerged in the upper basin of rivers during this period and the middle part of the river valleys were transformed into hanging valleys on the horsts thus drainage of the kestel polje system and horsts mountainous area that bordered the polje to the east was enabled through underground karst conduits consequently caco3 precipitating from waters coming out of the rich karst springs that fed the polje system and aquifers to the east formed the antalya tufa plateau

tectonics of se china new insights from the lushan massif jiangxi province in south china the lushan massif forms a topographic high of the south china block south of the qinling dabie belt the lushan massif consists of two main lithotectonic units separated by a major tectonic contact a neoproterozoic upper sinian paleozoic unit comprising primarily unmetamorphosed sandstones overlies a paleoproterozoic unit mainly composed of low pressure high temperature gneisses and micaschists both units are cut by cretaceous granitic intrusions three primary tectono metamorphic and magmatic events are recognized the eastern part of the lushan massif is cut by a nne ssw trending ductile normal fault d3 deformation coeval to the emplacement of a 100 110 ma leucogranite dated by 40ar 39ar laserprobe on biotite and muscovite d2 deformation is responsible for the formation of a decakilometer scale ne sw trending upright anticline characterized by ne sw stretching and nw se shortening the age of this folding event is defined by a 127 1 2 ma u pb titanite date obtained for a syntectonic granodiorite and 40ar 39ar ages of 133 ma for amphibole this cretaceous age also corresponds to the 40ar 39ar ages of 126 ma found on syntectonic muscovites at the base of the sinian unit an older deformation event d1 characterized by a top to the nw extensional decollement of the sinian paleozoic series above proterozoic metamorphic rocks is related to the triassic tectonics of the dabieshan lastly in the lower part of sinian rocks the occurrence of kyanite cataclased during d1 documents an older poorly preserved late paleozoic early mesozoic tectonometamorphic event dx related to a blind thrust in the continental crust of the south china block in the southern foreland of the dabieshan

dynamical response of the south asian monsoon trough to latent heating from stratiform and convective precipitation simulation experiments using a simplified atmospheric gcm and supplementary diagnostic analyses of observations are performed to understand how the south asian monsoon trough mt responds dynamically to latent heating from mesoscale convective systems mcss observations reveal that the mt during active monsoons is characterized by a deep cyclonic vorticity extending from the surface to 350 hpa and organized mcss covering over 3500 4000 km along the indo gangetic plains the mcss during active monsoons are composed of a relatively higher abundance of stratiform type precipitation mostly nimbostratus as compared to the convective type the results suggest that a stratiform type heating profile is very effective in promotingupward development of continental scale cyclonic circulation well above the midtroposphere over the mt region the vertical development involves a dynamical uplift of the layer of cyclonic circulation and is induced by midlevel 600 500 hpa convergence and vorticity stretching above 500 hpa by varying the population of stratiform and convective rain types in the simulation the horizontal scale of midlevel vorticity response is shown to increase significantly with stratiform population in contrast the midlevel response is more localized when the mcs is dominated by deep convective clouds for large stratiform populations the midlevel responseis found to extend far westward up to the northernflanks of the africanitcz indicativeof rossby wave dispersion of pv anomalies that are generated near the level of maximum heating gradient from the present findings one can conclude that the vertical deepening of mt during active monsoons is not merely a localized phenomenon instead it represents a large scale dynamical response to organized mcss that exert pivotal influence on the upward development of cyclonic circulation well above the midtroposphere

the akato tagh bend along the altyn tagh fault northwest tibet 2 active deformation and the importance of transpression and strain hardening within the altyn tagh system we investigated active deformation within the akato tagh restraining double bend to determine the age of the active altyn tagh fault relative to the altyn tagh system and thereby evaluate the extent to which this system evolved by net strain hardening or softening active structures were mapped based on their geomorphology and disruption of quaternary deposits surfaces the style of active faulting is strongly correlated with fault strike 065 070 striking segments show pure left slip whereas faults with more northward or eastward strikes are transtensional or transpressional respectively our mapping further suggests that the 065 to 070 striking western and eastern segments of the akato tagh bend are characterized by pure strike slip motion with partitioned transpression along the 090 striking central segment of the double bend it remains unclear how this active bend perpendicular shortening is absorbed in conjunction with previous work the present study fails to support the commonly held idea that tarim tibet motion is strongly oblique to the altyn tagh system estimates for the age of the akato tagh bend derived in a companion study suggest the bend is only a few million years old the current principal trace is probably similarly young because formation of the bend by recent deformation of an old trace should result in transpression along the western and eastern segments contrary to the pure left slip shown here the altyn tagh system comprises multiple fault strands in a zone 100 km wide across strike because the main trace appears to be much younger than the system in which it is embedded we speculate that this system evolved by the sequential formation and death of short lived fault strands in particular we suggest that geometrically complex strike slip fault systems such as the altyn tagh may form via system strain hardening where this net response reflects a dynamic competition between hardening and softening processes that are active simultaneously within the fault zone hardening mechanisms may include growth of restraining bend topography or material hardening of phyllosilicate rich gouge whereas softening processes might include r p shear linkage or reduction in bend angle by vertical axis rotation our analysis suggests that net strain hardening of a fault system can produce continental deformation that is spatially localized over the 1 5 m y during which an individual strand is active but distributed over the 10 100 m y corresponding to the life span of the whole fault system and the collision zone in which it is contained thus time scale is critically important in determining whether or not continental deformation is spatially distributed or localized

3h 3he dating a case for mixing of young and old groundwaters abstract 3 he 4 he and 20 ne 4 he ratios were measured in shallow underground waters opened by water supplying wells of the large vud javr intramountain artesian basin in the khibiny alkaline massif the kola peninsula the ratios vary from 1 321 10 6 to 2 065 10 6 and from 1 412 to 2 941 respectively and a well defined correlation is observed between them both these ratios in aquifers are known to be time dependent the former increases with time due to accumulation of 3he produced in waters by 3h decay the latter decreases due to migration of helium from water bearing rocks into the waters the correlation is interpreted as a result of the mixing of two different types of waters the approximation line enables us to estimate the isotopic ratios for the endmembers participating in the mixing and the mean residence time of tritigenic helium 3 in the water 1 1 3 he 4 he 3 655 10 6 20 ne 4 he 4 03 and taking into consideration 3h concentrations in the well waters 3h 31 1 tu practically the same for all samples 15 8 1 5 years for the young water 2 2 3 he 4 he 0 20 10 6 20 ne 4 he 0 18 and t 0 11 ma for the old one the contribution of the old water being less than 10 in one well a considerable contribution of modern day meteoric water about 16 is observed