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

late cenozoic thrusting of major faults along the central segment of longmen shan eastern tibet evidence from low temperature thermochronology abstract the cenozoic orogenic process of the longmen shan lms and the kinematics of major faults along the lms are crucial for understanding the growth history and mechanism of the eastern tibetan plateau three major faults from west to east are present in the central segment of the lms the wenchuan maoxian fault wmf the beichuan yingxiu fault byf and the jiangyou guanxian fault jgf previous researchers have placed great impetus on the pengguan massif between the wmf and byf however limited low temperature thermochronology data coverage in other areas prevents us from fully delineating the tectonic history of the lms in this study we collect 22 samples from vertical profiles in the xuelongbao massif and the range frontal area located at the hanging walls of the wmf and jgf respectively and conduct apatite and zircon fission track analyses new fission track data reveal that the xuelongbao massif has been undergoing rapid exhumation with an average rate of 0 7 0 9 mm yr since 11 ma and the range frontal area began rapid exhumation at 7 5 ma with total exhumation of 2 5 4 5 km the exhumation histories indicate that the three major faults wmf byf and jgf in the central lms are all reverse faults and show a basinward in sequence propagation from middle miocene to present day such a pattern further implies that upper crustal shortening is the primary driver for the lms uplift during the late cenozoic nevertheless middle lower crustal deformation is difficult to be constrained by the exhumation histories and its contribution to lms uplift cannot be ruled out

uplift of the emei shan western sichuan basin implication for eastward propagation of the tibetan plateau in early miocene abstract the emei shan stands on the southeast side of the longmen shan it marks the southeastern most edge of the eastern margin of the tibetan plateau emtp and towers above the sichuan basin to its east with the highest peak being 3099 m a large number of structural and thermo chronological studies have been published focused on the longmen shan orogen which is considered to be the northern part of the emtp however for the southern part of the emtp where the emei shan lies its tectonics and uplift history are still poorly understood this paper dates five granite samples from the emei shan batholith using the apatite fission track aft method the boundary faults of the emei shan and structural deformation in adjacent region are also investigated and mapped in detail 1 in miocene time compressional stress from the eastward extrusion of the emtp caused large scale thrusting and mountain uplift along narrow longmen shan in northern emtp in contrast to southern emtp where a broad and gentle yaan emei shan fold belt absorbed most of the stress by pliocene time the southeastward extrusion of the tibetan plateau caused the transpressional stress and rotated the chuandian fragment along the xianshuihe xiaojiang fault belt as a consequence the emei shan region was intended northeastwards into the sichuan basin bounded by two strike slip faults on its north and southeast sides 2 the aft results show the emei shan uplifted since 25 20 ma ago the threshold and main stage of uplift of the emei shan possibly lagged behind the longmen shan of approximately 5 myr as the leading edge of fold belt uplift of the emei shan indicated the eastward propagation of the emtp was time transgressive from late oligocene to middle miocene

meso cenozoic long term landscape evolution at the southern moroccan passive continental margin tarfaya basin recorded by low temperature thermochronology abstract this paper presents the first regional study of low temperature thermochronology to be undertaken in the tarfaya basin at the southern moroccan passive continental margin the basin is characterised by vast subsidence since mid triassic times whereby up to 12 km of meso to cenozoic sedimentary rocks accumulated the study focused on the post rift vertical movements along a typical passive margin and besides dealt with the timing and maximum temperature reached by potential source rocks of the basin to unravel the t t development thermochronological analyses were performed on 50 outcrop and well samples from meso cenozoic rocks thermochronological data reveal a continuous subsidence phase in the offshore basin from mid triassic to recent times in contrast apatite u th sm he and apatite fission track data as well as thermal modelling point to an inversion of the northeastern onshore basin starting in the palaeogene at 65 55 ma the rock uplift and exhumation period resulted in the erosion of a 1 0 1 4 km thick cretaceous palaeogene sedimentary pile contemporaneously with peak atlas surface uplift in the cenozoic the exhumation stage could be an explanation for the increasing periodic influx of detrital material into the offshore and southern onshore tarfaya basin since palaeocene detrital apatite fission track ages from 92 16 to 237 35 ma of the upper cretaceous neogene succession indicate no heating above 60 c confirming immature to early mature cenomanian to campanian and eocene source rocks in the onshore tarfaya basin

kinematic evolution of andean fold thrust structures along the boundary between the eastern cordillera and middle magdalena valley basin colombia 1 surface and subsurface data support a kinematic reconstruction of cenozoic fold thrust deformation along the eastern cordillera magdalena valley transition in colombia the la salina fault lsf marks the boundary between west vergent eastern cordillera structures and hinterland deposits of the middle magdalena valley basin apatite fission track and u th he thermochronological results for the west directed lsf reveal initial hanging wall exhumation during middle eocene early oligocene 45 30 ma shortening renewed exhumation in the early middle miocene 18 12 ma and accelerated late miocene pliocene 12 3 ma exhumation vitrinite reflectance data suggest maximum burial of 4 6 km helping constrain cenozoic basin architecture mapping of the lsf reveals hanging wall cretaceous eocene rocks in a broad anticline syncline pair with limited faulting and footwall eocene quaternary basin fill in a complex series of tight thrust related folds limited displacement along the westernmost frontal thrust suggests that shortening is largely accommodated by east directed thrusting within a broader triangle zone of a passive roof duplex and probable minor strike slip deformation in the preferred kinematic restoration the most recent phase of shortening to transpressional deformation represents out of sequence reactivation of the lsf consistent with irregular crosscutting relationships among footwall structures earliest exhumation by 45 30 ma in the eastern cordillera fold thrust belt is correlated with increased sedimentary lithic fragments and high compositional maturity in sandstones of the adjacent magdalena valley basin exhumation since 15 ma coincided with decreased compositional maturity and elevated accumulation rates for the real group the compositional provenance shifts are attributed to westward advance of fold thrust deformation into the proximal eastern segments of the magdalena valley basin

late miocene pleistocene evolution of india eurasia convergence partitioning between the bhutan himalaya and the shillong plateau new evidences from foreland basin deposits along the dungsam chu section eastern bhutan the shillong plateau is a unique basement cored uplift in the foreland of the eastern himalaya that accommodates part of the india eurasia convergence since the late miocene it was uplifted in the late pliocene to 1600 m potentially inducing regional climatic perturbations by orographically condensing part of the indian summer monsoon ism precipitations along its southern flank as such the eastern himalaya shillong plateau ism is suited to investigate effects of tectonics climate and erosion in a mountain range broken foreland system this study focuses on a 2200 m thick sedimentary section of the siwalik group strategically located in the lee of the shillong plateau along the dungsam chu at the front of the eastern bhutan himalaya we have performed magnetostratigraphy constrained by vitrinite reflectance and detrital apatite fission track dating combined with sedimentological and palynological analyses we show that 1 the section was deposited between 7 and 1 ma in a marginal marine deltaic transitioning into continental environment after 5 ma 2 depositional environments and paleoclimate were humid with no major change during the depositional period indicating that the orographic effect of the shillong plateau had an unexpected limited impact on the paleoclimate of the bhutanese foothills and 3 the diminution of the flexural subsidence in the basin and or of the detrital input from the range is attributable to a slowdown of the displacement rates along the main boundary thrust in eastern bhutan during the latest miocene pleistocene in response to increasing partitioning of the india eurasia convergence into the active faults bounding the shillong plateau

temperature limits for preservation of primary calcite clumped isotope paleotemperatures abstract solid state reordering of c o bonds in the calcite lattice can alter the clumped isotope composition of paleotemperature archives such as fossil brachiopod shells without inducing significant changes in shell microstructure and trace element concentrations metrics commonly used to gauge preservation quality to correctly interpret the paleoenvironmental significance of clumped isotope derived paleotemperatures it is necessary to understand the temperature time domain in which solid state c o bond reordering is important we address this question using a combination of laboratory and natural geological experiments on paleozoic brachiopod shells the laboratory experiments involve heating fossil brachiopod calcite at different temperatures and times to directly observe rates of 13 c 18 o bond reordering the resulting arrhenius parameters are indistinguishable from values previously determined for an optical calcite with similar trace element compositions we develop an alternative kinetic model for reordering that accounts for non first order reaction progress observed during the initial several hundred minutes of laboratory heating experiments and show that the simplified first order approximation model passey and henkes 2012 predicts reaction progress equally well for temperatures and timescales relevant to sedimentary basins we evaluate our laboratory based rate predictions by studying brachiopod calcite from several sedimentary basins with independently constrained burial temperature histories specifically we use the laboratory derived arrhenius parameters to predict the evolution of brachiopod calcite clumped isotope compositions during successive one million year time steps reflecting the burial and exhumation temperature paths of each basin while this exercise is limited by the relatively large uncertainties in the temperature histories of these basins we find general correspondence within error between predicted and observed clumped isotope values we present simplified temperature time diagrams for calcite showing domains where primary clumped isotope compositions will be preserved partially reordered and fully reordered in conclusion calcite samples dwelling at 100 c or lower for 10 6 10 8 year timescales should not be affected by solid state c o bond reordering

fundamentals of fission track thermochronology fission track ft analysis has developed into one of the most useful techniques used throughout the geologic community to reconstruct the low temperature thermal history of rocks over geological time the ft method is based on the accumulation of narrow damage trails i e fission tracks in uranium rich mineral grains e g apatite zircon titanite and natural glasses which form as a result of spontaneous nuclear fission decay of 238u in nature price and walker 1963 fleischer et al 1975 the time elapsed since fission tracks began to accumulate is estimated by determining the density of accumulated tracks in a particular material in relation to the uranium content of that material chemical etching can be used to enlarge fission tracks that have formed within a mineral in order to make them readily observable under an ordinary optical microscope price and walker 1962 if a host rock is subjected to elevated temperatures fission tracks that have formed up to that point in time are shortened progressively and eventually erased by the thermal recovery i e annealing of the damage fleischer et al 1975 because thermal diffusion basically governs the annealing process the reduction in ft length is a function of heating time and temperature importantly fission tracks are partially annealed over different temperature intervals within different minerals this characteristic allows for the construction of time temperature paths of many different rock types by a plotting ft and other isotopic ages from different minerals versus their closure temperatures which is applicable in the case of a monotonous cooling history e g wagner et al 1977 zeilter et al 1982 and or by b the inverse modeling of observed ft age and confined track length data e g corrigan 1991 lutz and omar 1991 gallagher 1995 ketcham et al 2000 see also ketcham 2005

can fission track annealing in apatite be described by first order kinetics abstract it is becoming commonplace to suggest that fission track annealing in apatite can be described by first order kinetics that is the decrease in track density and or length with time during isothermal annealing can be described by a single exponential equation a review of the literature reveals that there is no convincing evidence for such an assertion but more than ample evidence to the contrary simple graphical analysis of available annealing data from the literature clearly shows that the single exponential fails to adequately describe the data more rigorous statistical model fitting is not attempted due to the generally inadequate specification of annealing data in the literature most published annealing data suffer from flaws in experimental design that render them of limited value in defining viable kinetic models for the annealing process consideration of the processes taking place during annealing suggests that there is no good reason why first order kinetics would be expected to describe fission track annealing and more complex models should be considered in order to provide reliable data capable of yielding practically useful kinetic models laboratory annealing experiments should be designed to meet a number of strict criteria in identifying viable models the need is for those which adequately describe the data rather than for physically meaningful models although models should preferably be kept as simple as possible

thermal and exhumation history of sakhalin island russia constrained by apatite u pb and fission track thermochronology abstract sakhalin island represents a key locality to study the tectonic evolution of the western pacific the island is located at the amur okhotsk plate margin and records a complex thermotectonic history apatite double dating u pb and fission track and thermal history modelling were applied to three late eocene granitoid massifs within central and southern sakhalin the aniva okhotsk and langeri complexes apatite u pb results yield consistent late eocene 40 37 ma ages suggesting rapid post magmatic cooling apatite fission track results reveal bimodal age distributions with late eocene early oligocene 38 33 ma and early miocene 20 17 ma age populations that can be correlated with variations in uranium and chlorine concentrations thermal history modelling translates the aft age bimodality into two phase cooling histories the timing of the early cooling phase 38 33 ma corresponds with the apatite u pb ages indicating rapid cooling to at least 100 c during the late oligocene the second cooling phase at 20 17 ma cooled the samples to near surface temperatures both cooling phases correspond with regional unconformities and subsequent accelerations in sedimentation rate suggesting that cooling was a response to rapid exhumation in addition our data suggests that the studied terranes record differential exhumation with respect to the structural architecture the miocene exhumation pulse is coeval with the timing of transpressional fault displacement and the subsequent opening of the kuril basin

cooling exhumation and kinematics of the kanchenjunga himal far east nepal new single crystal 40ar 39ar and apatite fission track ages from the kanchenjunga region of far east nepal yield insight into the timing of assembly of the himalayan mid crust and the mechanisms that controlled its exhumation the 40ar 39ar data are compared with new u th pb zircon and monazite intrusive crystallization ages and existing metamorphic monazite ages from across the study area to test for internal consistency and potential excess ar contributions this new dataset which significantly enhances the density and spatial coverage available from the region shows that inferred thrust sense discontinuities within the now exhumed former midcrustal rocks exposed therein must have ceased motion by ca 12 ma furthermore the spatial distribution of ages across the kanchenjunga region older ages ca 12 16 ma to the south and north and younger ages ca 8 ma in the middle portion of the transect is compatible with simulations of tectonic enhanced exhumation above a developing duplex system in nearby bhutan

low temperature thermochronologic record of eocene migmatite dome emplacement and late cenozoic landscape development shuswap core complex british columbia exhumed mid to lower crustal rocks offer an opportunity to determine the mechanisms conditions timing and consequences of the ascent of hot rocks from deep to shallow crustal levels we used results of low t thermochronology zircon and apatite u th he apatite fission track to document the very shallow emplacement 1800 m have preserved eocene fission track ages and evidence of rapid cooling 60 c myr this eocene cooling event corresponds to rapid exhumation by upward flow of partially molten crust and final exhumation by detachment faulting samples collected below 1800 m in elevation display a wide range of apatite fission track ages 43 15 ma and track length distributions that reflect prolonged residence in the apatite partial annealing zone these age elevation relations imply that the dome rocks reached the near surface 2 km during initial upward flow and tectonic exhumation in the eocene and that little erosion of the eocene surface has occurred since that time thermal modeling of the lowest elevation samples 600 m and intrasample apatite u th he age variations reveal enhanced erosion and relief production at the onset of continental glaciations at 3 ma our work illustrates the dynamic links between deep and shallow crustal processes and the evolution of topography in a deeply incised hot orogen

the thermo tectonic history of the song kul plateau kyrgyz tien shan constraints by apatite and titanite thermochronometry and zircon u pb dating abstract the song kul basin sits on a plateau at the northern and middle kyrgyz tien shan junction it is a lacustrine basin occupied by lake song kul and predominantly developed on igneous basement this basement was targeted for a multi method chronological study to identify the different magmatic episodes responsible for basement formation and to constrain the timing of the development of its present day morphology zircon u pb dating by la icp ms revealed four different magmatic episodes a late cambrian 500 ma island arc system a late ordovician 450 ma subduction related intrusion an early permian 290 ma collisional stage and a middle to late permian 260 ma post collisional magmatic pulse middle to late triassic 200 230 ma titanite fission track ages and late triassic early jurassic 180 210 ma apatite fission track ages and thermal history modeling indicate the song kul basement was already emplaced in the shallow crust at that time an exhumed fossil apatite fission track partial annealing zone is recognized in the bordering song kul mountain ranges the area experienced only minor post early mesozoic denudation the igneous basement was slowly brought to apatite u th he retention temperatures in the late cretaceous palaeogene miocene to present reactivation of the tien shan does not manifestly affect this part of the orogen

neogene upper crustal cooling of the olympus range northern aegean major role of hellenic back arc extension over propagation of the north anatolia fault zone the north anatolian fault zone nafz is one of the most hazardous active faults on earth yet its pliocene space time propagation across the north aegean domain remains poorly constrained we use low temperature multi thermochronology and inverse thermal modelling to quantify the cooling history of the upper crust across the olympus range this range is located in the footwall of a system of normal faults traditionally interpreted as resulting from superposed middle late miocene n s stretching related to the back arc extension of the hellenic subduction zone and a pliocene quaternary transtensional field attributed to the south westward propagation of the nafz we find that accelerated exhumational cooling occurred between 12 and 6 ma at rates of 15 35 c ma 1 and decreased to 3 c ma 1 by 8 6 ma the absence of significant plio pleistocene cooling across olympus suggests that crustal exhumation there is driven by late miocene back arc extension while the impact of the nafz remains limited

radiation enhanced fission track annealing revisited and consequences for apatite thermochronometry apatite fission track aft analyses for granitoid and metamorphic bedrock samples from the western superior province ontario the churchill rae province melville peninsula and southampton islan

cenozoic denudation history of southern hainan island south china sea constraints from low temperature thermochronology abstract as a large block of continental crust hainan island located in the western south china sea forms a rift shoulder to the adjacent offshore yinggehai and qiongdongnan basins and lies in the footwall of their main boundary faults we present 11 apatite fission track aft data and 16 u th sm he ages to elucidate the island s cenozoic morphotectonic evolution our data indicate that much of southern hainan island experienced a well defined cooling episode commencing in late eocene oligocene time during this time most samples cooled from 110 c to 55 15 c at a rate of 4 0 c ma following which the cooling rate decreased to 2 5 c ma assuming a constant paleogeothermal gradient of 23 c km similar to that of the present day since oligocene time when most samples cooled into the base of the aft partial annealing zone the total eroded section is estimated at a minimum of 3 5 km about two thirds of which was removed during the oligocene rapid cooling phase this implies that elevation of southern hainan island has decreased since the oligocene and this is supported by independent paleobotanical evidence although a further cooling episode since 5 ma is also suggested by aft thermal history models cooling occurred from relatively low temperatures 45 50 c where annealing kinetics are not well understood so this cannot be rigorously assessed despite evidence for increased sedimentation in offshore basins at this time our data suggest that the no 1 fault of the adjacent offshore yinggehai basin to the west which is thought to be an offshore extension of the red river fault zone was mainly active from late eocene through much of the oligocene but declined rapidly after 22 ma the marked reduction of potential sediment supply rate from hainan island into neighboring basins after that time suggests that miocene to recent sedimentation in the yinggehai basin was mainly supplied by the red river

late cretaceous exhumation and uplift of the harz mountains germany a multi method thermochronological approach the harz mountains represent one of the most prominent surface expressions of late cretaceous intraplate shortening in central europe we present a comprehensive low temperature thermochronological data set zircon and apatite fission track and u th he covering the exhumed paleozoic basement of the harz mountains and the adjacent kyffhauser block as well as lower triassic sedimentary rocks of the western and southern rim of the harz mountains integration of results with sedimentological data from the syntectonic late cretaceous subhercynian basin allows for a detailed reconstruction of the timing of uplift and erosion of the harz mountains the data reveal that i tectonic reorganization and initial exhumation started at around 90 ma ii uplift and emergence caused erosion of the mesozoic sedimentary cover between 86 85 ma and 83 82 ma and iii erosion of at least 3 4 km of underlying paleozoic rocks followed and continued into the paleogene the thickness of removed overburden amounts to at least 6 km and most erosion occurred in santonian to campanian time at minimum rates of 0 5 km myr the southwestern rim of the harz has exhumed slower over a longer period of time and may record a phase of late cretaceous syntectonic sediment accumulation

long term landscape evolution and post rift reactivation in the southeastern brazilian passive continental margin taubate basin zircon zft and apatite aft fission track low temperature thermochronology was applied at the brazilian passive continental margin in order to understand and reconstruct the post rift evolution since the breakup of southwestern gondwana the thermochronological data obtained from samples of both the precambrian basement and the paleogene to neogene sedimentary rocks from the continental rift of southeastern brazil provided zft ages between 148 15 and 64 6 ma and aft ages of 81 8 29 3 ma these data clearly indicate syn and post rift reactivations during the early cretaceous with great emphasis on paleogene to neogene times integrating the results of older thermochronological studies the reactivation of the southeastern brazilian margin can be described in three main phases related to the rift to post rift evolution of se brazil in general zft and aft data yield spread values that become younger as samples are closer to the reactivated neoproterozoic shear zones and might reflect source area exhumation the analysis of zft and aft data allowed interpretations regarding the main phases that occurred in the study area related to the thermotectonic and tectono stratigraphic evolution in southeastern brazil

thermochronology quantifying exhumation history of the wudang complex in the south qinling orogenic belt central china the wudang complex located in the central part of south qinling has been inferred to be a segment of the yangtze craton involved in the orogen in this study the cooling exhumation history of the wudang complex is revealed through combined published geochronology data and new apatite fission track results three rapid exhumation episodes related to relevant geodynamic events have been identified previous 40 ar 39 ar and u th he data indicate that the most significant exhumation induced by the collision between the north and south china blocks occurred from c 237 to 220 ma after long term subsidence and sedimentation of the passive continental margin the second exhumation event related to the long distance effect of the pacific subduction occurred during the period from c 126 to 90 ma following the late cretaceous eocene peneplanation stage the final late cenozoic exhumation since c 15 ma may be attributed to the combined effect of the eastward growth of the tibetan plateau uplift and the asian monsoon

thermal history of the westernmost eastern alps penninic rhenodanubian flysch nappes helvetic nappes and subalpine molasse thrust sheets the frontal part of the westernmost eastern alps comprises from top to bottom of the austroalpine and penninic nappes ultrahelvetic slices and two helvetic thrust sheets thrust upon the northern alpine molasse basin the thermal evolution of the penninic rhenodanubian flysch nappes the helvetic nappes and the allochthonous part of the alpine molasse basin is constrained by vitrinite reflectance measurements and apatite fission track dating and implemented in a tectonic evolution scheme within the helvetic nappes vitrinite reflectance increases regionally from north to south and stratigraphically from the campanian maastrichtian wang formation to the toarcian mols member apatite fission track ages from penninic and subalpine molasse units are consistently younger than the deposition age they indicate therefore a post depositional thermal overprint exceeding approximately 120 c the upper temperature limit of the apatite partial annealing zone 1d thermal modelling suggests that the penninic nappes attained deepest burial between the latest cretaceous and early palaeocene with the penninic basal thrust being located at approximately 8 km in the north compared to approximately 12 km in the south deepest burial of the upper helvetic nappe occurred between the latest eocene and early miocene its base was buried down to approximately 10 5 km in the north compared to 11 5 km in the south exhumation of the entire nappe stack started in the early to middle miocene for both penninic and helvetic models a heatflow minimum during the cenozoic deformation max 27 32 mw m2 followed by an increase from the middle miocene onwards up to 60 mw m2 was assumed

late cretaceous cenozoic tectonic sedimentary evolution and u enrichment in the southern songliao basin abstract late cretaceous cenozoic tectonic sedimentary evolution is fundamental to u uranium migration and u enrichment in the southern songliao basin northeast china to establish the genetic connection between tectonic sedimentary evolution and u enrichment this paper presents a mineralogical study apatite fission track aft analysis and sem cl analysis of quartz grains two stages of mineralization were proposed including the u pre enrichment stage during the late cretaceous and the ore forming stage during the cenozoic based on the density plots of the aft ages paleoclimate studies and sem cl analysis of quartz grains it is inferred that the u pre enrichment was closely related to the rapid uplift of the great xing an range and the zhangguangcai range and the o2 rich atmosphere during 97 90 ma in the southern songliao basin the o2 rich atmosphere increased u mobility and led to the formation of red beds during the late cretaceous which widely developed u pre enrichment in the basins of northeast china the mineralogical study reveals that the qianjiadian uranium deposit developed in two stages the diagenetic process experienced the transition from early alkaline to late acidic conditions to promote the stage i mineralization u pre enrichment the dominant occurrence spaces for u were the dissolution pores of quartz tightly packed with calcite cement u enrichment during alkaline ambient conditions was mainly via adsorption with the increase of the buried depth the early alkaline diagenesis returned to acidic conditions due to the abundant organic material u vi was reduced to pitchblende due to the reducing capacity of the organic matter om stage ii ore forming stage mineralization was strictly related to the hydrocarbon re concentration according to the thermal history study of the cc1 and q2 boreholes the southern songliao basin experienced four episodes of rapid uplift during the cenozoic at 83 80 ma 68 52 ma 33 23 ma and 8 ma respectively the cenozoic uplifts led to hydrocarbon migration at 65 ma 23 ma and present the re concentration of hydrocarbon prompted the u mineralization in the qianjiadian uranium deposit in the southern songliao basin during the stable period of tectonic movements the reducing conditions caused by hydrocarbons promoted u mineralization the dominant spaces of coffinite were intergranular dissolved pores formed during the transformation from the feldspar to the kaolinite under acidic conditions the post rift phase and structural inversion phase directly controlled the u pre enrichment stage and the ore forming stage respectively overall the tectonic sedimentary evolution played an important role in controlling the u leaching from granites the dominant occurrence spaces and u recycling

thermochronology constraints on miocene exhumation in the central range mountains trinidad the central range fault zone is a continental transform that accommodates most of the present day slip between the caribbean and south american plates in trinidad global positioning system data and paleoseismic work suggest that this zone is active today and has been active for at least the past several thousand years the modern fault zone overprints a middle miocene fold and thrust belt therefore the strain recorded in the central range fault zone is the sum of both middle miocene and more recent events thermochronology data from eocene and oligocene sandstones in the central range were collected to evaluate the timing of exhumation driven by crustal shortening and thickening u th he zircon analysis of subhedral zircons collected from eight samples indicated that the burial temperatures of these sedimentary rocks did not exceed 180 c suggesting that these grains record detrital u th he dates apatite fission track aft analysis of 10 samples yielded mixed results with cooling ages ranging from 30 to 15 ma however most sites failed the 2 test suggesting that multiple age cohorts are present pooled aft ages suggest that rocks presently at the surface were exhumed through their aft closure temperature ca 11 18 ma cooling and exhumation thus most likely resulted from middle miocene shortening across the fold and thrust belt in response to early oblique convergence between the caribbean and south america plates post miocene deformation associated with more recent transform tectonics has therefore resulted in more limited 4 km if any exhumation

thermochronology of lower cretaceous source rocks in the idaho wyoming thrust belt lower cretaceous organic rich source rocks that are thermally mature to postmature crop out on the absaroka darby and prospect plates in linear belts that run parallel to the trace of the thrusts in the idaho wyoming portion of the idaho wyoming utah thrust belt although the common assumption is that burial by thrust plates and the synorogenic sediments derived from them have been responsible for thermal maturation of the organic rich strata commercial amounts of hydrocarbons have not been found in structural traps in this portion of the thrust belt in a companion paper burtner and nigrini demonstrated that gravity driven fluid flow in the idaho wyoming portion of the thrust belt was responsible for moving large amounts of heat from the depths of the early cretaceous foreland basin eastward toward the stable platform in this paper we demonstrate through the application of organic maturation indicators and a new refinement of the apatite fission track technique that this process heated lower cretaceous organic rich source rocks to temperatures sufficient to generate hydrocarbons hydrocarbon generation and migration occurred prior to the development of the thrusts that are often assumed to have played a major role in the generation and entrapment of hydrocarbons in this portion of the thrust belt

duskside enhancement of equatorial zonal electric field response to convection electric fields during the st patrick s day storm on 17 march 2015 the equatorial zonal electric field responses to prompt penetration of eastward convection electric fields ppef were compared at closely spaced longitudinal intervals at dusk to premidnight sectors during the intense geomagnetic storm of 17 march 2015 at dusk sector indian longitudes a rapid uplift of equatorial f layer to 550 km and development of intense equatorial plasma bubbles epbs were observed these epbs were found to extend up to 27 13 n and 25 98 s magnetic dip latitudes indicating their altitude development to 1670 km at apex in contrast at few degrees east in the premidnight sector thailand indonesian longitudes no significant height rise and or epb activity has been observed the eastward electric field perturbations due to ppef are greatly dominated at dusk sector despite the existence of background westward ionospheric disturbance dynamo idd fields whereas they were mostly counter balanced by the idd fields in the premidnight sector in situ observations from swarm a and swarm c and communication navigation outage forecasting system satellites detected a large plasma density depletion near indian equatorial region due to large electrodynamic uplift of f layer to higher than satellite altitudes further this large uplift is found to confine to a narrow longitudinal sector centered on sunset terminator this study brings out the significantly enhanced equatorial zonal electric field in response to ppef that is uniquely confined to dusk sector the responsible mechanisms are discussed in terms of unique electrodynamic conditions prevailing at dusk sector in the presence of convection electric fields associated with the onset of a substorm under southward interplanetary magnetic field bz

fission track dating of faulting events accommodating plastic deformation of biotites we performed fission track ft analyses to constrain the timing of fault slip events associated with plastic deformation of biotite grains formed at high temperature higher than 200 300 c apatite ft ages of 49 6 16 7 ma were obtained from late cretaceous granites near the fault with younger ages near a basaltic dike that intruded at 19 ma by comparing the distribution of apatite ft ages using forward thermal and ft annealing calculations we interpreted the younger ages as being explained by basaltic intrusion we concluded that the plastic deformation of the biotite grains could have occurred associated with the following events 1 primal cooling of the granitic body at 68 50 ma and or 2 basaltic intrusion at 19 ma a combination of detailed observation of microscale deformation structures and dense ft measurements successfully constrained timing of fault events distributed in bedrock without covering layers

apatite fission track analysis apatite fission track aft analysis has been widely used during the past 30 years to constrain the low temperature thermal histories of many igneous metamorphic and sedimentary rocks in a wide range of geological settings applicable geological settings include orogenic belts rifted margins faults sedimentary basins cratons and mineral deposits the types of geologic problems that can be addressed include the timing and rates of tectonic events sedimentary basin evolution the timing of hydrocarbon generation and ore mineralization the absolute age of volcanic deposits the effects of major climatic changes on the near surface geothermal gradient and long term landscape evolution early work by naeser 1967 and wagner 1968 1969 first established the basic procedures that enabled the fission track dating method to be applied routinely to these geologic problems fleischer et al 1975 summarized the early studies of the broader discipline of nuclear track detection in different solid state materials more recent comprehensive overviews of fission track applications have been provided by naeser and mcculloh 1989 wagner and van den haute 1992 gallagher et al 1998 van den haute and de corte 1998 dumitru 2000 and gleadow et al 2002 etched natural fission tracks in several apatite grains are shown in figure 1 successful aft analysis is limited by the following 1 the availability of apatite from which useful aft data can be obtained often due to a lack of apatite of sufficient grain size and quality within available rock types or alternatively the lack of available rock samples due to minimal outcrop exposure or other reasons 2 economic considerations in terms of the time and money required to obtain sufficient aft data 3 the inherent limitations of aft data to resolve geological thermal history information often related to limited numbers of accumulated spontaneous fission tracks due to

k ar illite and apatite fission track constraints on brittle faulting and the evolution of the northern norwegian passive margin abstract determining the timing of post caledonian brittle faulting in northern norway is important for the understanding of the extensional tectonic evolution of the north norwegian continental margin fault gouges from the troms and vesteralen regions of northern norway yield carboniferous to permian and carboniferous to cretaceous k ar illite ages respectively the results show a contrast in fault activity and exhumation between the troms and the vesteralen regions while major faulting in the troms region appears to have ceased after the permian faulting event faulting continued into at least the cretaceous in the vesteralen region the findings highlight the importance of a widespread permian tectonic event followed by a distinct southwestward migration of post permian tectonic activity on the north norwegian passive margin late triassic to early jurassic apatite fission track ages do not show significant age offsets across major fault zones in troms indicating that most or all of fault activity took place prior to the late triassic the thermal history models are consistent and indicate continuous cooling to about 60 c in the late permian triassic

timing and rate of exhumation along the litang fault system implication for fault reorganization in southeast tibet the litang fault system that crosses the litang plateau a low relief surface at high elevation 4200 4800 m above sea level that is not affected by regional incision provides the opportunity to study exhumation related to tectonics in the se tibetan plateau independently of regional erosion combining apatite and zircon fission track with apatite u th he thermochronologic data we constrain the cooling history of the litang fault system footwall along two transects apatite fission track ages range from 4 to 16 ma ahe ages from 2 to 6 ma and one zircon fission track age is 99 ma these data imply a tectonic quiet period sustained since at least 100 ma with a slow denudation rate of 0 03 km ma interrupted at 7 to 5 ma by exhumation at a rate between 0 59 and 0 99 km ma we relate that faster exhumation to the onset of motion along the left lateral normal litang fault system that onset is linked to a lower miocene important kinematic reorganization between the xianshuihe and the red river faults with the eastward propagation of the xianshuihe fault along the xiaojiang fault system and the formation of the zhongdian fault such strike slip faults allow the sliding to the east of a wide continental block with the litang fault system accommodating differential motion between rigid blocks the regional evolution appears to be guided by the strike slip faults with different phases of deformation which appears more in agreement with an hidden plate tectonic model rather than with a lower channel flow model

vertical tectonics at a continental crust oceanic plateau plate boundary zone fission track thermochronology of the sierra nevada de santa marta colombia 1 the topographically prominent sierra nevada de santa marta forms part of a faulted block of continental crust located along the northern boundary of the south american plate hosts the highest elevation in the world 5 75 km whose local base is at sea level and juxtaposes oceanic plateau rocks of the caribbean plate quantification of the amount and timing of exhumation constrains interpretations of the history of the plate boundary and the driving forces of rock uplift along the active margin the sierra nevada province of the southernmost sierra nevada de santa marta exhumed at elevated rates 0 2 km my during 65 58 ma in response to the collision of the caribbean plateau with northwestern south america a second pulse of exhumation 0 32 km my during 50 40 ma was driven by underthrusting of the caribbean plate beneath northern south america subsequent exhumation at 40 25 ma 0 15 km my is recorded proximal to the santa marta bucaramanga fault more northerly regions of the sierra nevada province exhumed rapidly during 26 29 ma 0 7 km my further northward the santa marta province exhumed at elevated rates during 30 25 ma and 25 16 ma the highest exhumation rates within the sierra nevada de santa marta progressed toward the northwest via the propagation of nw verging thrusts exhumation is not recorded after 16 ma which is unexpected given the high elevation and high erosive power of the climate implying that rock and surface uplift that gave rise to the current topography was very recent i e 1 ma and there has been insufficient time to expose the fossil apatite partial annealing zone

thurston island west antarctica between gondwana subduction and continental separation a multistage evolution revealed by apatite thermochronology

fission track dating of phosphate minerals and the thermochronology of apatite several phosphate minerals have been investigated for their usefulness in geochronology and thermochronology by the fission track method of these apatite ca5 po4 3 f cl oh has proved pre eminently suitable for this purpose for reasons discussed below apatite was one of the first minerals amongst many others to be investigated for fission track dating by fleischer and price 1964 and has subsequently become by far the most important of all the minerals used for dating by this method the usefulness of apatites for fission track dating arises from their near universal tendency to concentrate uranium within their structure at the time of crystallization and their widespread occurrence in all of the major rock groups price and walker 1963 first recognized the possibility that the accumulation of radiation damage tracks in natural minerals from the spontaneous nuclear fission of 238u within their lattices could be used for geological dating they also demonstrated that a simple chemical etching procedure served to enlarge these fission tracks to optical dimensions so that they could be observed and measured under an ordinary optical microscope price and walker 1962b 1963 this simple procedure quickly opened the way for a wide range of nuclear particle track studies in natural minerals and glasses e g fleischer et al 1975 the most important of which was fission track dating fleischer et al 1964 also showed that spontaneous or fossil fission tracks provided an explanation for various anomalous etch pits in apatite which had puzzled crystallographers over many years the essence of a fission track age determination involves measuring the number of tracks that have accumulated over the lifetime of the mineral along with an estimate of the amount of uranium that is present knowing the rate of spontaneous fission decay a geological age can be calculated detailed

on the calibration of fission track annealing models to obtain thermal histories from fission track length data the rates at which track lengths are reduced must be estimated the usual method is to use empirical equations calibrated via laboratory analogues a major concern is the extrapolation of the equations to predict temperatures on the geological time scale which is far outside the range of the calibration data using objective statistical criteria it is shown that the inclusion of geological data from age standards and deep boreholes is an important measure to ensure that model predictions of geological annealing rates are at least close to being correct it is shown that high temperature geological data should be the preferential target in the search for new field evidence a discussion on the use and limitations of geological data and their consequences is presented

kinematic flexural and thermal modelling in the central andes unravelling age and signal of deformation exhumation and uplift abstract quantifying age rate and lateral variation of deformation and exhumation in convergent systems relies on integration of geologic map patterns ag and locations of reset thermochronometer systems and synorogenic sediment distribution the central bolivian andes provide an ideal location to examine the influence of variations in shortening and stratigraphic architecture on the structural evolution of the mountain range due to differential age and rates of shortening and distinct sedimentary basin geometries along strike to quantify age and rate of shortening we link thermokinematic modelling of sequentially deformed forward modelled balanced cross sections to synorogenic and thermochronologic histories the preserved basin history in the altiplano and eastern cordillera argues for an early fold and thrust belt located in the now western cordillera with subsequent propagation of shortening eastward around 40 50 ma flexural modelling incorporating isostasy and erosion requires multiple basement thrust sheets with 35 97 km of displacement a temporally evolving effective elastic thickness as well as imposed subsidence in the foreland and uplift in the hinterland is required to reproduce the surface geology increase subandean foreland basin depth limit altiplano sedimentation and facilitate altiplano uplift to modern elevation thermokinematic modelling is compatible with initiation of deformation at 50 40 ma in a marked increase in subandean velocities from 5 5 to 8 10 mm yr from 12 10 ma to present out of sequence thrusting at the westernmost limit of the subandes is required to match measured young and partially reset zircon helium ages out of sequence faulting is supported by high ksn values indicative of active uplift and was likely promoted by the abrupt eastern edge of the paleozoic basin rocks which limited forward propagation of structures and or increased erosion due to focused precipitation our results highlight the importance of incorporating detailed structural modelling in differentiating the geometry kinematics and timing of deformation to reproduce thermochronologic ages and basin histories

the relationship between track shortening and fission track age reduction in apatite combined influences of inherent instability annealing anisotropy length bias and system calibration abstract the relationship between reduced track density 0 and reduced mean confined track length l l 0 during annealing has been studied for both spontaneous and induced tracks in four apatite samples with different chemical composition compositional range and origin and with spontaneous tracks giving mean confined track lengths varying from 14 5 m down to 12 3 m in all four apatites induced tracks show a relationship between l l 0 and 0 composed of two regions at higher values the two appear to be equal while at lower values l l 0 is greater than 0 this can be understood qualitatively in terms of the anisotropy of annealing and the bias against revelation of short tracks data from three apatites of uniform composition show near identical relationships in a sample showing a range of apatite compositions the point of divergence from the 1 1 relationship is somewhat higher than in the uniform composition apatites because individual grains anneal at different rates and the presence of highly annealed grains affects the track density more strongly than the mean track length spontaneous tracks show similar relationships to those observed for induced tracks in each sample when the data are renormalised to allow for the natural annealing present in the spontaneous tracks previous studies which led to the idea of length reduction without density reduction for spontaneous tracks did not renormalise density data as well as length data thereby distorting the apparent relationship data for the multi compositional apatite sample where annealing has taken place in geological conditions also agrees with the laboratory annealing data for both spontaneous and induced tracks this consistency suggests that a single process is responsible in all three cases implying that a laboratory based description of annealing can be applied to geological conditions with confidence recognition that spontaneous tracks in apatite are commonly annealed suggests that in general the fission track age should be interpreted as a reflection of both the time over which tracks have been retained and the distribution of etchable track lengths since the latter is a manifestation of the thermal history the fission track age should be interpreted in similar terms

experimental evidence for the pressure dependence of fission track annealing in apatite abstract fission track analysis has seen a major expansion in application to general geological problems reflecting its advances in understanding the temperature dependence of track annealing and track length distributions however considerable uncertainties still persist in particular concerning the stability of fission tracks subjected to the interaction of environmental physical parameters e g pressure temperature stress and in extrapolation of laboratory data to geological time scales in this work we studied the fading behavior of spontaneous fission tracks in basic apatite hexagonal ca5 po4 3 oh f cl when exposed simultaneously to laboratory pressures temperatures and stress over varying time spans the experiments showed that track fading is a complex recovery mechanism which is extremely sensitive to the coupling of these three parameters in particular a strong decrease in the fission track fading rate was observed as a function of increasing pressure and a nearly temperature independent dramatic increase in fission track recovery was observed as a function of stress consequently 1 the stability field of fission tracks in apatite increases towards temperatures higher than 110 c depending on the absolute pressure 2 closure ages in apatite are underestimated 100 for an ideal geothermobarometric gradient 3 related exhumation and erosion rates are overestimated above the closure temperature and underestimated below the closure temperature and 4 since the widely applied statistical description of thermally induced fading kinetics does not account for the influences of either pressure or stress and is based on fission track annealing data produced at ambient pressure the accuracy in extrapolating fission track data to geological time scales and in their application to dynamical systems must be cast into doubt

variation in apatite fission track length measurement implications for thermal history modelling abstract predictive thermal history modelling using apatite fission track ft data is dependent on an algorithm to describe the time and temperature dependency of ft annealing which in turn relies on the empirical determination of ft length as a measure of the annealing process assessment of variation in ft length measurement is poorly described with few comparisons between analysts and little interlaboratory standardisation using apatites of various compositions containing induced tracks annealed to differing degrees this study has assessed variation in horizontal confined track length measurement for a variety of procedural conditions replicate analysis by a single observer is typically within 3 but increases inversely with track length comparison between observers on the same samples shows significant generally nonsystematic variation between observers for a complex length distribution variation is 12 sources of variation are identified as a variation from track revelation including etching track in track tint vs track in cleavage tincle measurement and use of 252 cf irradiation to produce additional etching channels b bias in measurement including equipment analytical procedures and sample size and c observer bias principally differences in and consistency of personal technique 5 m hno 3 is preferred to weaker etchants although more anisotropic tracks are better defined permitting more rigorous measurement while c axis parallel sections where 2 4 geometry is better defined are more easily identified for all but the longest length distributions tincles are significantly longer than tints with few short tincles at high angles measurement of tincles effectively masks the anisotropy of annealing 252 cf irradiation is effective in increasing the number of tints sampled and measured variation between values measured for unirradiated and cf irradiated aliquots does not exceed that found for a single analyst although a slight systematic shift to longer lengths for cf irradiated samples is seen as reported by other workers track length distributions are anisotropic anisotropy increasing with annealing level track angle exerts a major influence on measured length summing affects from annealing and etching anisotropies with observer bias track angle should be accommodated within the annealing algorithm it is recommended that similar track revelation observation and measurement conditions are used for the analysis of field samples as are used in annealing experiments and subsequently employed in numerical models to predict thermal history a parallel argument can be advanced for using samples of similar composition further we recommend that the ft community should seek as a matter of some urgency a programme of interlaboratory comparison of track length measurement using standard apatite samples containing artificial length distributions typifying various levels of complexity such comparisons would provide a more rigorous baseline for thermal history prediction in geological case studies

cretaceous reactivation and intensified erosion in the archean proterozoic limpopo belt demonstrated by apatite fission track thermochronology abstract cratons are generally assumed to be regions of long lasting tectonic stability in particular the study of the phanerozoic exhumation history of cratons has been largely hampered by the scarcity of suitable stratigraphic controls onshore this fact is even more pronounced in terranes lacking mesozoic or younger penetrative structural fabrics and metamorphic overprinting our study in the limpopo belt shows that modern apatite fission track thermochronology provides a hitherto unavailable perspective in the study of these rocks and has profound implications for the crustal evolution of the zimbabwe craton apatite fission track data from 35 samples taken along two transects in the southern edge of the zimbabwe craton and in the central zone of the limpopo belt suggest that extensive regions experienced kilometer scale exhumation in two discrete events as recently as the cretaceous the first occurred at around 130 ma and the second at around 90 ma basin subsidence and sedimentation loads on the mozambique margin support the timing of these events and provide strong indications of the source and pathways for the eroded material further the results indicate that young and old surfaces in a geomorphological sense may be structurally juxtaposed in regions of high elevation in zimbabwe this is contrary to early ideas of surface chronologies based on summit accordances or invoking pediplanation

mesozoic and cenozoic exhumation history and magmatic hydrothermal events of the central tianshan mt range nw china evidence from u th he and 40ar 39ar dating abstract the thermal history of rocks in the awulale area central chinese tianshan is significant to understanding the formation and tectonothermal evolution of the tianshan orogen k feldspar 40ar 39ar and apatite u th he age data reveal at least four mesozoic cenozoic tectonothermal events in the central tianshan which occurred during the middle late triassic 244 4 216 5 ma early jurassic ca 180 3 ma early cretaceous 99 1 98 1 ma and early miocene 18 6 13 7 ma this thermal history is consistent with that throughout the tianshan orogenic belt and surrounding blocks modeling of the thermal history shows that intrusive rocks in the central tianshan have experienced four stages of cooling in the mesozoic cenozoic stage i occurred from ca 310 to 230 ma after magma emplacement and resulted in cooling to the 40ar 39ar closure temperature of k feldspar 200 180 c during this time tectonism in the central tianshan was not intense and the rapid cooling was due mainly to thermal exchange with a maximum cooling rate of 7 1 c myr stage ii occurred from ca 230 to 180 ma collision between the qiangtang microcontinent and the eurasia continental margin resulted in active tectonism in the central tianshan and cooling was caused mainly by tectonic uplift with the maximum uplift of intrusive rocks exceeding 9 km stage iii occurred from ca 180 to 45 ma when regional tectonism was weak and cooling was gradual during this stage the apatites in the syenite porphyry remained in the he partial retention zone for a long time this indicates that during this stage the central tianshan was only weakly influenced by the far field collisions of lassa and karakoram pamir with the southern margin of eurasia stage iv occurred from 45 ma to the present day and was related to the far field influence of the middle late himalayan orogeny during which tectonism in the central tianshan became more intense in this final stage many types of intrusive rock were exhumed to the surface with the maximum uplift exceeding 2 km furthermore the cooling history and regional structural trends indicate that since the mesozoic under the influence of tectonic compression there has been differential uplift on the northern and southern sides of the east awulale area the cooling and exhumation rates of intrusive rocks are much higher on the northern side of the area than the southern side this was related to reverse movement on the yuximolegai fault as exhumation rate of the hanging wall northern region was higher than that of the footwall southern region under n s compression these findings combined with the inversion model results indicate that this differential uplift occurred mainly from the late triassic to early jurassic

exhumation of the southern pyrenean fold thrust belt spain from orogenic growth to decay 1 the deformation and exhumation history of an orogen reflects the interactions between tectonic and surface processes we investigate orogenic wedge deformation erosion and sedimentation in the pyrenees by a quantifying the spatiotemporal patterns of exhumation across the southern fold thrust belt ftb with bedrock apatite fission track aft thermochronology and b comparing the results with existing deformation exhumation and sedimentation chronologies eighteen new samples record exhumation during and after orogenesis between 90 and 10 ma rocks from the range core axial zone record rapid exhumation that progresses east to west and north to south consistent with patterns of tectonically driven uplift synorogenic sediments shed into piggyback basins on the southern fold thrust belt during mountain building retain a detrital exhumation signal from the axial zone in contrast samples from other structural positions record exhumation of the thin skinned pyrenean thrust sheets suggesting sediment burial and heating of sufficient magnitudes to reset the aft system 3 km in some locations exhumation of these fold thrust structures is likely an erosional response to thrust driven rock uplift we identify an exhumation phase 25 20 ma that occurs along the central and eastern spanish pyrenees at the boundary between thick and thin skinned portions of the wedge we suggest that this distributed exhumation event records a a taper response in the southern orogenic wedge to sediment loading and or b a shift to wetter stormier climate conditions following convergence driven uplift and full topographic development a final exhumation phase between 20 and 10 ma may record the excavation of the southern fold thrust system following base level lowering in the ebro basin

mesozoic and cenozoic tectonics of the northeastern edge of the tibetan plateau evidence from modern river detrital apatite fission track age constraints abstract thermochronometry of modern river sands exploits the natural sampling of detritus in a river catchment to infer plausible regional exhumation patterns when combined with available bedrock thermochronometric information apatite fission track age distributions for six detrital samples are reported in this study to resolve the exhumation history of the upper reaches of the heihe river draining north qilian shan and tuole shan the northeastern margin of the tibetan plateau the apatite fission track aft ages include four major populations late paleozoic 300 55 293 43 ma early mesozoic 223 15 205 17 ma late jurassic cretaceous 112 6 2 84 8 5 6 ma and cenozoic 63 8 5 9 19 3 1 7 ma the ages of these populations correspond well with the deformation and cooling history of the study area the late paleozoic and early mesozoic aft age populations record cooling events resulting from continental collision between the qiantang and kunlun blocks the late jurassic cretaceous aft age populations are interpreted to record cooling events associated with exhumation of north qilian shan and tuole shan due to the collision of the lhasa block with asian continent the cenozoic aft age populations record several cooling events a cooling event is recorded corresponding to exhumation of north qilian shan and tuole shan due to late stress from the lhasa asia collision causing deformation nearly synchronous with the india asia collision another cooling event is recorded corresponding to uplift and exhumation in oligocene time due to ongoing india asia convergence north qilian shan and tuole shan were constructed as a distal effect of india asia convergence in the early miocene while approaching their present mountain river basin distributions thermochronometry applied to heihe river sediments provide convinced evidence of multi stage exhumation of most northeastern margin of the tibetan plateau in the late paleozoic cenozoic

thermochronological evidence for a late pliocene climate induced erosion rate increase in the alps u th he and fission track analyses of apatite along deep seated tunnels crossing high relief mountain ranges offer the opportunity to investigate climate tectonic forcing on topographic evolution in this study the thermochronologic analysis along the simplon tunnel western central alps italy and switzerland constrains in detail the mechanisms controlling the topographic evolution of the simplon massif cooling rates vary from about 10 c ma at about 10 ma to about 35 c ma in the last 3 ma such increase in cooling rates corresponds to the inception of glacial cycles in the northern hemisphere age patterns show correlation with faults distribution until 2 ma suggesting that tectonics controlled rocks exhumed up to that age after 2 ma thermo chronometric data show that the simplon area has experienced primarily erosional exhumation all age patterns provided are not affected by topographic effects thus indicating that present day topography has been carved in the last 2 ma most likely controlled by glacial erosion

on the occurrence of anomalous fission tracks in apatite and titanite in annealing experiments on natural crystals of apatite and titanite two types of fission track were observed that had not been identified previously 1 stable tracks and 2 tracks through fluid inclusions stable tracks do not shorten significantly even when heated to temperatures well above those normally sufficient for complete annealing of fission tracks tracks through fluid inclusions owe their excessive length to the fact that one fission fragment traveled through a fluid inclusion without appreciable energy loss if they go undetected both types of track can distort the temperature time paths constructed on the basis of confined fission track length measurements simple measures are proposed to avoid these pitfalls

control of geomorphic processes on 10be concentrations in individual clasts complexity of the exposure history in gobi altay range mongolia the dating of alluvial landforms by cosmogenic nuclides requires distinguishing the pre deposition inheritance from the post deposition history of the clasts in the studied marker moreover estimating catchment scale erosion rates from the concentrations of cosmogenic nuclides in active alluvia requires a good knowledge of the local regional relationships between rock exhumation and transport through space and time this is still poorly known for timescales of tens of thousand years in order to document the evolution of clast exhumation and transport rates through time we analyze in situ 10be concentrations in boulders and cobbles from hillslopes to outlet of an arid mountainous catchment located in gobi altay mongolia strongly affected by global climatic changes during the pleistocene holocene period samples were collected on bedrock abandoned alluvial deposits active colluvia and alluvia our results show a large 10be scattering in the active river bed consistent with a low and discontinuous catchment erosion rate dominated by mass wasting and fluvial incision on the contrary pre exposure signal within abandoned terraces is much more homogeneous consistent with climatic pulses responsible of strong erosional events on hillslopes and rapid fluvial transport these results show that exhumation transport processes at the catchment scale vary in style and intensity through time as a consequence of climatic oscillations the occurrence of abrupt climatic changes during short periods of time recorded by 10be concentrations in abandoned alluvia raise questions about the temporal applicability of catchment erosion rates derived from cosmogenic nuclide concentrations measured in sediments of active rivers on the other hand strong and short erosion events limit and homogenize the pre exposure 10be signal in associated deposits like debris flows making them particularly suitable markers for dating in active tectonic and paleoclimatic studies

low temperature thermochronology of anticosti island a case study on the application of conodont u th he thermochronology to carbonate basin analysis abstract the ordovician to silurian carbonate succession preserved on anticosti island is a near continuous record of the changing depositional and tectonic history of the early paleozoic laurentian margin these strata are a prime natural laboratory to test the applicability of conodont apatite u th he thermochronology cahe for carbonate basin analysis in a setting with a well understood burial history and abundant paleotemperature constraints we report 63 cahe dates from seven samples collected from two boreholes x ray micro computed tomography xr ct was used to assess individual conodont element size volume and alpha ejection correction cahe dates are negatively correlated with effective uranium concentration eu with single conodont dates enigmatically older than the age of deposition to conodont dates as young as 2 7 0 2 ma we rationalize this dispersion as a product of several factors including diagenetic processes and pervasive conodont crystalline porosity and permeability additionally one basement and two sandstone samples were collected for apatite and zircon u th he ahe zhe and apatite fission track aft thermochronology in the precambrian basement zhe dates range from 581 7 46 5 ma to 761 2 60 9 ma n 4 and ahe dates range from 26 7 1 6 to 48 4 2 9 ma n 4 ahe dates from two lower ordovician sandstones n 8 are positively correlated with eu increasing from 13 7 0 8 ma to 105 2 6 3 ma over a range of 186 ppm eu thermal history modeling of these data suggests two plausible thermal histories both of which are novel as they imply that far field effects related to the opening of the atlantic ocean have influenced the thermal history of anticosti island ultimately these data highlight the complexities associated with and necessity of low temperature thermochronology in carbonate basins

the temporal evolution of the active margin along the southeast anatolian orogenic belt se turkey evidence from u pb ar ar and fission track chronology abstract the southeast anatolian orogenic belt saob resulted from the north dipping subduction of the southern neotethyan oceanic lithosphere in late mesozoic and early cenozoic however the timing and the rate of the continental collision are still under debate here we present new u pb ar ar and fission track ages from the i type calc alkaline granitoids esence dogansehir and baskil cutting the goksun ispendere and komurhan ophiolites and also the malatya keban metamorphics representing the tauride active continental margin along the saob in this study high to low temperature thermochronological methods applied to the granitoids are used to understand the temporal and geodynamic evolution of the tauride active continental margin and continental collision between tauride and arabian platforms in the frame of the neotethyan convergence during cretaceous and miocene the u pb zircon ages range from 83 to 88 ma for the baskil and from 81 to 83 ma for the esence granitoids the 39 ar 40 ar ages indicate that these late cretaceous granitoids cooled below 300 c in 6 10 ma the formation ages and the timing of the gradual cooling of the late cretaceous granitoids are similar to metamorphism age and the timing of the exhumation of the hp lt bitlis metamorphics during this stage the combined field geochemistry and geo thermochronological data suggest that the first continental collision event occurred between bitlis puturge micro continents to the south and tauride platform to the north in an oblique subduction zone between 84 and 74 ma the granitoids continued uplifting during early middle eocene together with the exhumation of hp uht berit metaophiolite in an extensional regime related to the opening of the maden back arc basin this period also let the intrusion of the dogansehir arc magmatism intruding the puturge and malatya keban metamorphics berit metaophiolite and maden complex the eocene dogansehir granitoid has similar u pb and 39 ar 40 ar ages suggesting a fast cooling the apatite fission track aft ages for all granitoid bodies suggest that they were mainly cooled or uplifted in two episodes where the first one is in the eocene in an extensional setting the aft data marked the final continental collision between the taurides and the arabian platform first in oligocene and the break off of the subducted slab and the delamination process caused fast uplift of the eastern anatolia during middle to late miocene

the effect of inherited paleotopography on exhumation of the central andes of nw argentina differential exhumation in the puna plateau and eastern cordillera of nw argentina is controlled by inherited paleostructures and resulting paleotopography related to the cretaceous salta rift paleomargins the ceno zoic deformation front related to the development of the andean retro arc orogenic system is generally associated with 4 km of exhumation which is recorded by cenozoic apatite fi ssion track aft and u th sm he ages he ages in the eastern cordillera of nw argentina new aft ages from the top of the nevado de cachi document oligocene ca 28 ma cooling which combined with existing data indicates exhumation of this range between ca 28 ma and ca 14 ma however some of the highest ranges in the eastern cordillera preserve cretaceous ages indicative of limited cenozoic exhumation samples collected from an similar to 3 km elevation transect along the northern part of the sierra de quilmes paleorift fl ank laguna brava show aft ages between ca 80 and ca 50 ma and he ages between ca 45 and ca 10 ma another set of samples from an similar to 1 km elevation transect farther to the southwest la quebrada shows cretaceous aft ages between ca 116 ma and ca 76 ma and mainly cretaceous he ages in agreement with aft data analysis of existing aft and he ages from the area once occupied by the salta rift reveals a pattern characterized by cretaceous ages along paleorift highs and cenozoic ages within paleorift hanging wall basins and later foreland basin depocenters this pattern is interrupted by the sierras pampeanas at similar to 28 degrees s which record mid cenozoic ages our data are consistent with a complex inherited pattern of pre andean paleostructures likely associated with paleotopography which was beveled by the cenozoic regional foreland basin and reactivated during the late neogene ca 10 ma strongly controlling the magnitude of cenozoic uplift and exhumation and thus cooling age distribution this combined with variable lithologic erodibility resulted in an irregular distribution of themochronological ages

unraveling the mesozoic and cenozoic tectonothermal evolution of the eastern basque cantabrian zone western pyrenees by low temperature thermochronology this is a contribution of the geotec group idi 2018 000216 and projects misterios cgl2013 48601 c2 2 r consolider ingenio 2010 topo iberia csd2006 00041 and esf topoeurope project pyrtec sv pa 10 03 ip2 pyrtec we thank additional financial support by the university of oviedo banco santander the government of the principality of asturias through the science technology and innovation plan pcti the european union through feder funds and the spanish ministry of education culture and sport through the training programme for academic staff fpu grant for idf

variability of apatite fission track annealing kinetics ii crystallographic orientation effects a method is presented that permits the length of any horizontal confined fission track inclined at a specified angle to the crystallographic c axis in apatite to be converted to an equivalent track length parallel to the crystallographic c axis the model is based on the results of annealing experiments for six selected apatites five calcian fluorapatites and durango apatite representing a subset of the 15 total apatite specimens studied an iterative process of calculation is required to project fission track lengths onto the c axis and computer source code implementing the solution to this problem is presented this method of projecting apatite fission track lengths onto the crystallographic c axis is shown to remove effectively fission track length variation within single fission track populations due to anisotropic track length reduction for all 15 apatites studied in addition a model is developed that offers predictions that closely reproduce published experimental data concerning the relationship between fission track density etched fission tracks per unit area of apatite surface and the arithmetic mean fission track length finally it is shown that natural fission track populations exhibit fission track length anisotropy similar to that of fission track populations created and annealed in the laboratory this observation implies that the same process by which apatite fission tracks anneal in the laboratory is responsible for annealing of apatite fission tracks in the geological environment

from orogen to passive margin constraints from fission track and u th he analyses on mesozoic uplift and fault reactivation in sw norway the post caledonian tectonic history and landscape evolution of southwestern norway are poorly understood primarily owing to the lack of onshore post devonian sediments to bridge this knowledge gap low temperature thermochronological techniques were applied to investigate vertical movements in the upper crust new apatite fission track and apatite and zircon u th he analyses on samples from southwestern norway yielded permian to jurassic triassic to cretac eous and carboniferous to triassic ages respectively thermal history modelling indicates rela tively high cooling rates 2 3 8 cm a 21 throughout permian to early jurassic times since the jurassic samples from coastal areas have remained close to the surface and were reheated to 30 50 8c during sedimentary burial in the cretaceous inland samples experienced lesser amounts of permo triassic exhumation continued to cool slowly 1 8 cm a 21 throughout the jurassic cretaceous and did not reach the surface until the cenozoic both fission track and u th he ages are offset across faults highlighting the importance of fault activity throughout the mesozoic in combination with previously published results the new data suggest that the geo morphological evolution of southwestern norway is closely connected to rift and post rift tec tonics related to north sea and north atlantic rifting the topographic relief was most likely repeatedly rejuvenated during periods of tectonic activity

neogene exhumation in the outer western carpathians terra nova 23 283 291 2011 abstract apatite fission track analysis was used to investigate the cenozoic tectonic evolution of the polish sector of the outer western carpathians where thrusting was overlapped by extension in the last 10 ma the results show a general decrease of burial degree towards the european foreland and a range of cooling ages between 26 and 7 ma younger ages 10 7 ma are confined to the eastern region whereas exhumation in the central western region is about 10 ma older and is characterized by no major age differences among structural units therefore exhumation of the chain is inferred to have occurred since the early miocene when it appears to have been essentially coeval with thrusting whereas extensional tectonics is likely to have played an important role during late miocene exhumation

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

exploiting radiation damage control on apatite u th he dates in cratonic regions abstract apatites from four pairs of samples of precambrian basement from the western canadian shield were analyzed by u th he thermochronometry to test for the influence of radiation damage on apatite u th he dates in this cratonic region recent studies have demonstrated that the accumulation of radiation damage increases the apatite he retentivity so that apatites with a span of effective u concentrations eu that experienced the same thermal history may be characterized by a range of closure temperatures in this investigation each sample pair consisted of a mafic dike cross cutting felsic gneisses from a single outcrop or nearby outcrops that contained apatites with a span of eu the apatites yielded u th he dates from 846 to 123 ma and were positively correlated with eu within each sample pair these results can be explained using a model that tracks the evolution of he mobility in response to the accumulation of radiation damage when coupled with regional geological constraints the data appear to require partial to complete he loss due to burial and reheating in phanerozoic time new apatite fission track dates and length data were obtained for five of these samples the apatite fission track dates are proterozoic regardless of apatite eu thermal history simulations indicate that the apatite fission track data are compatible with the u th he results although the thermal histories are not identical in detail and the fission track results alone do not require phanerozoic heating together the data are consistent with burial of this region by 1 km of phanerozoic strata that were subsequently denuded thus pointing toward significant phanerozoic deposition in the north american cratonic interior hundreds of kilometers east of where previously documented the results suggest that exploiting radiation damage control on apatite u th he dates through investigation of surface sample apatites with a span of closure temperatures can impose tighter restrictions on thermal histories in low relief cratonic landscapes than was previously possible

post variscan thermal history of the intra sudetic basin sudetes bohemian massif based on apatite fission track analysis the intra sudetic basin a 12 km deep variscan intramontane basin has the best preserved post orogenic sedimentary record available at the ne margin of the bohemian massif apatite fission track aft analyses have been performed on 16 sedimentary and volcanic samples of carboniferous to cretaceous age from the intra sudetic basin to improve understanding of the post variscan thermal evolution aft central ages range from 50 1 8 8 to 89 1 7 1 ma early eocene to coniacian with 13 of them being late cretaceous the mean track length values range from 12 5 0 4 to 13 8 0 5 except for one sample 14 4 0 2 m this relatively short mean track length together with the unimodal track length distributions and rather low standard deviation 0 8 to 1 7 m in most samples indicate a long stay in the partial annealing zone during slow cooling however in the northern part of the intra sudetic basin samples show a wider track length distribution standard deviation of 1 8 to 2 1 m that could indicate a more complex thermal evolution possibly related to mesozoic reheating vitrinite reflectance data combined with thermal models based on the aft results indicate that the carboniferous strata reached maximum palaeotemperatures in the latest carboniferous to early permian time corresponding to a major coalification event the second phase of temperature rise occurred due to late mesozoic sedimentary burial but it had no influence on maturation of the carboniferous organic matter final cooling phase in the late cretaceous paleogene was related to tectonic inversion of the intra sudetic basin which occurred after deposition of a significant thickness of cenomanian turonian sediments thermal modelling demonstrates that 4 km thick cover of upper cretaceous sediments is required to obtain a good match between our aft data and modelled time temperature paths this outcome supports a significant amount of late cretaceous paleogene inversion within the variscan belt of central europe

apatite fission track chronometry using laser ablation icp ms abstract comparison is made of apatite fission track ft ages measured by using conventional thermal neutron irradiation and laser ablation inductively coupled plasma mass spectrometry la icp ms to determine sample uranium content spontaneous track densities were determined on specified apatite grains from the durango fish canyon tuff and mount dromedary complex age standards neutron induced track densities and icp ms uranium values were determined for the same specified grains ages determined using the two approaches show reasonable consistency indicating the possibility of routine fission track analysis using la icp ms uncertainties and assumptions in the la icp ms approach include the laser ablation of chemically etched mineral surfaces the suitability of reference materials for calibration and the derivation of ft ages using the alternatives of selection of a f value or a revised zeta comparative approach the use of la icp ms in ft chronometry would dramatically increase the speed of analysis and hence sample throughput as well as avoiding the need for neutron irradiation and the production transport and handling of radioactive samples with the acknowledged dependency of ft annealing in apatite on composition such grain by grain multi element analysis could provide a more robust definition of the specific track annealing characteristics of each apatite crystal

a mid palaeozoic ocean continent transition in the mazongshan subduction accretion complex beishan nw china new structural chemical and age data constrain the petrogenesis and tectonic evolution

the tectonics and paleo drainage of the easternmost himalaya arunachal pradesh india recorded in the siwalik rocks of the foreland basin the siwalik sedimentary rocks of the himalayan foreland basin preserve a record of himalayan orogenesis paleo drainage evolution and erosion this study focuses on the still poorly studied easternmost himalaya siwalik record located directly downstream of the namche barwa syntaxis we use luminescence palaeomagnetism magnetostratigraphy and apatite fission track dating to constrain the depositional ages of three siwalik sequences the sibo outcrop upper siwalik sediments at ca 200 800 ka the remi section middle and upper siwalik rocks at 0 8 8 8 2 4 ma and the siang section middle siwalik rocks at 9 3 1 5 to 13 5 1 5 ma cretaceous paleogene detrital zircon and apatite u pb ages characteristic of the transhimalayan gangdese batholiths that crop out northwest of the syntaxis are present throughout the sibo remi and siang successions confirming the existence of a yarlung brahmaputra connection since at least the late miocene a ca 500 ma zircon population increases up section most strikingly sometime between 3 6 to 6 6 ma at the expense of transhimalayan grains we consider the ca 500 ma population to be derived from the tethyan or greater himalaya and we interpret the up section increase to reflect progressive exhumation of the namche barwa syntaxis early cretaceous zircon and apatite u pb ages are rare in the sibo remi and siang successions but abundant in modern siang river sediments zircons of this age range are characteristic of the transhimalayan bomi chayu batholiths which crop out east of the syntaxis and are eroded by the parlung river a modern tributary of the siang river we interpret the difference in relative abundance of early cretaceous zircons between the modern and ancient sediments to reflect capture of the parlung by the siang after 800 ka

cenozoic uplift exhumation and deformation in the north kuqa depression china as constrained by u th he thermochronometry placing spatial and temporal constraints on deformation uplift and exhumation using thermochronology methods can shed light on cenozoic orogenic evolution in the kuqa foreland new apatite u th he and previously published apatite fission track thermochronology are combined with vitrinite reflectance data and modeling to compile a low temperature multi stage thermal history of tectonic uplift thrust and exhumation a rapid uplift and exhumation event originated in south tianshan during the eocene 46 ma with systematic younging of mean apatite u th he ages from north to south from the margin towards the interior uplift and exhumation south edge of the biyoulebaoguzi anticline in the northern monocline belt at 36 ma with more than 3400 m of stratum denuded subsequently deformation and uplift south edge of the biyoulebaoguzi anticline in the northern monocline belt at 36 ma with more than 3400 m of stratum denuded subsequently deformation and uplift extended to the northern edge of kelasu yiqikelike at 10 ma and then at 6 ma the kanyaken anticline formed and uplifted resulting in 3000 3700 m of overburden erosion the data support sequential southward propagating deformation and uplift inferred exhumation in the north kuqa depression during the cenozoic probably as a result of the collision of india with asia far to the south of the tianshan

zircon fission track thermochronology and applications to fault studies zircon is one of the most useful minerals used to unravel the earth s history recorded in rocks after the success of etching fission tracks in zircon fleischer et al 1964 naeser 1969 krishnaswami et al 1974 early studies focused primarily on dating young volcanic horizons for stratigraphic purposes e g naeser et al 1973 hurford et al 1976 seward 1979 gleadow 1980 kowallis et al 1986 kohn et al 1992 subsequently fission track analysis of zircon has been extensively employed along with other radiometric dating methods such as u pb and u th he techniques e g davis et al 2003 reiners 2005 to understand the thermochronology of rocks in a variety of geological settings i e thermal history analysis of basement rocks for orogenic studies e g zeilter et al 1982 hurford 1986 kamp et al 1989 sorkhabi 1993 seward and mancktelow 1994 hasebe and tagami 2001 spikings et al 2001 thermochronology using detrital zircon grains in sedimentary rocks for provenance analysis and thermal history analysis in or near faults which will be highlighted below in this present chapter the thermal sensitivity of the zircon fission track thermochronometry is reviewed in the context of laboratory and field studies then laboratory procedures of the zircon fission track analysis using the external detector method are outlined as practiced in the fission track laboratory of kyoto university for basic fundamentals of these fission track analyses including data analysis and graphical displays see the chapter by tagami and o sullivan 2005 finally as an example of recent geological applications of the technique the results of zircon fission track analysis of the nojima fault zone japan are presented these rocks were the target of systematic drilling of an active fault system using five boreholes and a trench applications to other geological settings and the