Exhuming Asia-A thermochronological perspective： Preface

Asia is the largest continent on Earth and records a prolonged history of continental growth and tectonic reactivation during the Phanerozoic. Several tectonic forces at the continental palaeomargins induced mountain building, both at the margins themselves （e.g. the Himalayas） and into the continental interior （e.g. the Tianshan）.

Fetkin-hydro,a new thermo-hydrological algorithm for low-temperature thermochronological modeling

Despite two decades of major advances in the field of thermochronological modeling,state-of-the-art numerical implementations still rely mostly on burial and exhumation processes to explain radiometric measurements.Even though such an approach has proved valuable,failing to account for other first-order geological variables has led to misinterpretations and therefore,calls for a refinement.In this study a new version of the Fetkin(finite element temperature kinematics,Ecopetrol)program is presented.Its new algorithm couples time-dependent hydrological and thermal calculations,thus rendering thermochronological ages that,instead of being solely dependent on the kinematical evolution of a system,conditioning by the fluid flow is also present.In contrast with previous thermochronological models,this work considers the influence of effective stress on rock properties(porosity and permeability)and therefore,in thermal conductivity.Sensitivity analyses addressing relevant geological questions show not only the versatility of the code but also,new perspectives on forward low-temperature thermochronological modeling.Groundwater circulation through pure-sandstone settings produce colder thermal architectures than those obtained in impermeable domains.Differences in cooling ages from models with and without fluid circulation are up to 5 Myr.A 4-fold variation in thrusting rates(0.5 km/Myr to 2 km/Myr)produces a 15-Myr difference in cooling ages in models with fluid flow,which contrasts to much lower differences,only 2 Myr,in domains without(or minimal)fluid circulation.2D thermal solutions in fold-bend-fold thrust belts composed of sandstones remain static despite substantial relief development by kinematic folding.A case-study from Western Argentina,in the Andean Precordillera,confirms the plausibility of the numerical algorithm here posed and raises new questions on the first-order thermal controls in settings under deformation.

Thermochronological constraints on two pulses of Cenozoic high-K magmatism in eastern Tibet

The previously published U-Pb and 40Ar/39Ar ages and our 21 newly-obtained 40Ar/39Ar ages suggest that the Cenozoic magmatism in eastern Tibet and Indochina occurred in two episodes, each with distinctive geochemical signatures, at (40—28) Ma and (16—0) Ma. The older rocks are localized along the major strike-slip faults such as the Jinsha-Red River fault system and erupted synchronously with transpression. The younger rocks are widely distributed in rift basins and coeval with the east-west extension of Tibet and eastern Asia. Combining with their geochemical data, we consider that the earlier magmatic phase was generated by continental subduction, while the later volcanic phase was caused by decompression melting of a recently meta- somatically-altered, depleted mantle source. The magmatic gap between the two igneous pulses represents an important geodynamic transition in the evolution of eastern Tibet, from the processes controlled mainly by crustal deformation to those largely dominated by mantle tectonics.

Paleotopographic Reconstruction on the Basis of Low-Temperature Thermochronological Thermal History Modelling

The traditional paleotopographic explanation of mountain belts from low-temperature thermochronology is based on the simulation of low-temperature age data, the main defect of which is that we cannot make comparisons at the same time between the samples. In this article, we intend to make paleotopographic reconstruction on the basis of thermal history modelling. We first digitalize the thermal history curve and take contemporary temperatures for comparison, then reconstruct the pa- leotopography according to the distribution of the samples＇ temperatures. The finite difference method is used to solve the diffusion equation for heat in the reconstruction process. Our paleotopography re- construction method can restore the topography over time. However, due to the nature of thermal his- tory modeling and the noise in the data, the accuracy of this reconstruction is currently limited.

Thermal Evolution of Plutons and Uplift Process of the Yanshan Orogenic Belt

Abstract: Thermochronological dating was used to study the thermal evolution of the Mesozoic plutons and uplift history of the Yanshan orogenic belt. The results show that the cooling history of the plutons is complicated, corresponding to the inhomogeneous uplift process of the Yanshan orogenic belt. The Panshan granite cooled fast during 226.48–204.95 Ma at a rate of 10.22°C/Ma after its emplacement at a depth of about 10 km, and its fast uplift occurred in about 96–35 Ma at an average rate of 0.115 mm/a. The Wulingshan pluton cooled fast during 132–127.23 Ma at a rate of 94.34°C/Ma, and its rapid uplift occurred in 86–45 Ma at an average rate of 0.186 mm/a. The Yunmengshan granite cooled fast during 143–120.99 Ma at a rate of 19.51°C/Ma, and its rapid uplift occurred in 106–103.95 Ma and 20–0.0 Ma at a rate of 1.06 mm/a and 0.15 mm/a respectively. The Sihetang granite-gneiss uplifted rapidly since 13 Ma at an average rate of 0.256 mm/a. The Badaling granite uplifted rapidly since 6 Ma at an average rate of 0.556 mm/a. The Cenozoic uplift of the Yanshan Mountains can be well correlated to the rifting process of the surrounding basins.

Exhuming the Meso-Cenozoic Kyrgyz Tianshan and Siberian Altai-Sayan:A review based on low-temperature thermochronology

Thermochronological datasets for the Kyrgyz Tianshan and Siberian Altai-Sayan within Central Asia reveal a punctuated exhumation history during the Meso-Cenozoic. In this paper, the datasets for both regions are collectively reviewed in order to speculate on the links between the Meso-Cenozoic exhumation of the continental Eurasian interior and the prevailing tectonic processes at the plate margins. Whereas most of the thermochronological data across both regions document late Jurassic -Cretaceous regional basement cooling, older landscape relics and dissecting fault zones throughout both regions preserve Triassic and Cenozoic events of rapid cooling, respectively. Triassic cooling is thought to reflect the Qiangtang-Eurasia collision and/or rifting/subsidence in the West Siberian basin. Alternatively, this cooling signal could be related with the terminal terrane-amalgamation of the Central Asian Orogenic Belt. For the Kygyz Tianshan, late Jurassic-Cretaceous regional exhumation and Cenozoic fault reactivations can be linked with specific tectonic events during the closure of the Palaeo-Tethys and Neo-Tethys Oceans, respectively. The effect of the progressive consumption of these oceans and the associated collisions of Cimmeria and India with Eurasia probably only had a minor effect on the exhumation of the Siberian Altai-Sayan. More likely, tectonic forces from the east （present-day co- ordinates） as a result of the building and collapse of the Mongol-Okhotsk orogen and rifting in the Baikal region shaped the current Siberian Altai-Sayan topography. Although many of these hypothesised links need to be tested further, they allow a first-order insight into the dynamic response and the stress propagation pathways from the Eurasian margin into the continental interior.

Latest Triassic to Early Jurassic Thrusting and Exhumation in the Southern Ordos Basin, North China: Evidence from LA-ICP-MS-based Apatite Fission Track Thermochronology

The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track （AFT） thermochronology to unravel the timing of thrusting and exhumation for the Laolongshan-Shengrenqiao Fault （LSF） in the southern Ordos Basin. The AFT ages from opposite sides of the LSF reveal a significant latest Triassic to Early Jurassic time-temperature discontinuity across this structure. Thermal modeling reveals at the latest Triassic to Early Jurassic, a ~50~C difference in temperature between opposite sides of the LSF currently exposed at the surface. This discontinuity is best interpreted by an episode of thrusting and exhumation of the LSF with -1.7 km of net vertical displacement during the latest Triassic to Early Jurassic. These results, when combined with earlier thermochronological studies, stratigraphic contact relationship and tectono-sedimentary evolution, suggest that the southern Ordos Basin experienced coeval intense tectonic contraction and developed a north-vergent fold-and-thrust belt. Moreover, the southern Ordos Basin experienced a multi-stage differential exhumation during Mesozoic, including the latest Triassic to Early Jurassic and Late Jurassic to earliest Cretaceous thrust-driven exhumation as well as the Late Cretaceous overall exhumation. Specifically, the two thrust-driven exhumation events were related to tectonic stress propagation derived from the latest Triassic to Early Jurassic continued compression from Qinling Orogenic Collage and the Late Jurassic to earliest Cretaceous intracontinental orogeny of QinUng Orogenic Collage, respectively. By contrast, the Late Cretaceous overall exhumation event was related to the collision of an exotic terrain with the eastern margin of continental China at -100 Ma.

Burial and exhumation history of the Xigaze forearc basin, Yarlung suture zone. Tibet

The Cretaceous-Eocene Xigaze forearc basin is a crucial data archive for understanding the tectonic history of the Asian continental margin prior to and following collision with India during the early Cenozoic Era. This study reports apatite and zircon(U-Th)/He thermochronologic data from fourteen samples from Albian-Ypresian Xigaze forearc strata to determine the degree and timing of heating(burial) and subsequent cooling(exhumation) of two localities along the Yarlung suture zone(YSZ) near the towns of Saga and Lazi. Thirty-seven individual zircon He ages range from 31.5 ± 0.8 Ma to6.06 ± 0.18 Ma,with the majority of grains yielding ages between 30 Ma and 10 Ma. Twenty apatite He ages range from 12.7 ± 0.5 Ma to 3.9 ± 0.3 Ma,with the majority of grains yielding ages between 9 Ma and 4 Ma. These ages suggest that the Xigaze forearc basin was heated to 140-200 ℃ prior to cooling in Oligocene-Miocene time. Thermal modeling supports this interpretation and shows that the samples were buried to maximum temperatures of ～140-200 0 C by 35-21 Ma, immediately followed by the onset of exhumation. The zircon He and apatite He dataset and thermal modeling results indicate rapid exhumation from ～21 Ma to 15 Ma, and at ～4 Ma. The 21-15 Ma thermochronometric signal appears to be regionally extensive, affecting all the lithotectonic units of the YSZ, and coincides with movement along the north-vergent Great Counter Thrust system. Thrusting, coupled with enhanced erosion possibly related to the paleo-Yarlung River, likely drove Early Miocene cooling of the Xigaze forearc basin.In contrast, the younger phase of rapid exhumation at ～4 Ma was likely driven by enhanced rock uplift in the footwall of north-striking rifts that cross-cut the YSZ.

Meso-Cenozoic Tectonothermal History of Permian Strata, Southwestern Weibei Uplift: Insights from Thermochronology and Geothermometry

This study provides an integrated interpretation for the Mesozoic-Cenozoic tectonothermal evolutionary history of the Permian strata in the Qishan area of the southwestern Weibei Uplift,Ordos Basin.Apatite fission-track and apatite/zircon(U-Th)/He thermochronometry,bitumen reflectance,thermal conductivity of rocks,paleotemperature recovery,and basin modeling were used to restore the Meso-Cenozoic tectonothermal history of the Permian Strata.The Triassic AFT data have a pooled age of^180±7 Ma with one age peak and P(χ2)=86%.The average value of corrected apatite(U-Th)/He age of two Permian sandstones is^168±4 Ma and a zircon(U-Th)/He age from the Cambrian strata is^231±14 Ma.Bitumen reflectance and maximum paleotemperature of two Ordovician mudstones are 1.81%,1.57%and^210℃,~196℃respectively.After undergoing a rapid subsidence and increasing temperature in Triassic influenced by intrusive rocks in some areas,the Permian strata experienced four cooling-uplift stages after the time when the maximum paleotemperature reached in late Jurassic:(1)A cooling stage(~163 Ma to^140 Ma)with temperatures ranging from^132℃to^53℃and a cooling rate of^3℃/Ma,an erosion thickness of^1900 m and an uplift rate of^82 m/Ma;(2)A cooling stage(~140 Ma to^52 Ma)with temperatures ranging from^53℃to^47℃and a cooling rate less than^0.1℃/Ma,an erosion thickness of^300 m and an uplift rate of^3 m/Ma;(3)(~52 Ma to^8 Ma)with^47℃to^43℃and^0.1℃/Ma,an erosion thickness of^500 m and an uplift rate of^11 m/Ma;(3)(~8 Ma to present)with^43℃to^20℃and^3℃/Ma,an erosion thickness of^650 m and an uplift rate of^81 m/Ma.The tectonothermal evolutionary history of the Qishan area in Triassic was influenced by the interaction of the Qinling Orogeny and the Weibei Uplift,and the south Qishan area had the earliest uplift-cooling time compared to other parts within the Weibei Uplift.The early Eocene at^52 Ma and the late Miocene at^8 Ma,as two significant turning points after which both the rate of uplift and the rate of temperature changed rapidly,were two key time for the uplift-cooling history of the Permian strata in the Qishan area of the southwestern Weibei Uplift,Ordos Basin.

Thermo-tectonic history of the Junggar Alatau within the Central Asian Orogenic Belt(SE Kazakhstan,NW China):Insights from integrated apatite U/Pb,fission track and(U-Th)/He thermochronology

The Junggar Alatau forms the northern extent of the Tian Shan within the Central Asian Orogenic Belt(CAOB)at the border of SE Kazakhstan and NW China.This study presents the Palaeozoic-Mesozoic post-collisional thermo-tectonic history of this frontier locality using an integrated approach based on three apatite geo-/thermochronometers:apatite U-Pb,fission track and(U-Th)/He.The apatite U-Pb dates record Carboniferous-Permian post-magmatic cooling ages for the sampled granitoids,reflecting the progressive closure of the Palaeo-Asian Ocean.The apatite fission track(AFT)data record(partial)preservation of the late Palaeozoic cooling ages,supplemented by limited evidence for Late Triassic(~230-210 Ma)cooling and a more prominent record of(late)Early Cretaceous(~150-110 Ma)cooling.The apatite(U-Th)/He age results are consistent with the(late)Early Cretaceous AFT data,revealing a period of fast cooling at that time in resulting thermal history models.This Cretaceous rapid cooling signal is only observed for samples taken along the major NW-SE orientated shear zone that dissects the study area(the Central Kazakhstan Fault Zone),while Permian and Triassic cooling signals are preserved in low-relief areas,distal to this structure.This distinct geographical trend with respect to the shear zone,suggests that fault reactivation triggered the Cretaceous rapid cooling,which can be linked to a phase of slab-rollback and associated extension in the distant Tethys Ocean.Similar conclusions were drawn for thermochronology studies along other major NW-SE orientated shear zones in the Central Asian Orogenic Belt,suggesting a regional phase of Cretaceous exhumation in response to fault reactivation at that time.

Post-Triassic thermal history of the Tazhong Uplift Zone in the Tarim Basin, Northwest China: Evidence from apatite fssion-track thermochronology

The Tarim Basin is a representative example of the basins developed in the northwest China that are characterized by multiple stages of heating and cooling.In order to better understand its complex thermal history,apatite fission track （AFT） thermochronology was applied to borehole samples from the Tazhong Uplift Zone （TUZ）.Twelve sedimentary samples of Silurian to Triassic depositional ages were analyzed from depths coinciding with the apatite partial annealing zone （～60-120 ℃）.The AFT ages,ranging from 132 ± 7 Ma （from a Triassic sample） to 25 ± 2 Ma （from a Carboniferous sample）,are clearly younger than their depositional ages and demonstrate a total resetting of the AFT thermometer after deposition.The AFT ages vary among different tectonic belts and decrease from the No.Ten Faulted Zone （133-105 Ma） in the northwest,the Central Horst Zone in the middle （108-37 Ma）,to the East Buried Hill Zone in the south （51 25 Ma）.Given the low magnitude of post-Triassic burial heating evidenced by low vitrinite reflectance values （Ro ＜ 0.7％）,the total resetting of the AFT system is speculated to result from the hot fluid flow along the faults.Thermal effects along the faults are well documented by younger AFT ages and unimodal single grain age distributions in the vicinity of the faults.Permian-early Triassic basaltic volcanism may be responsible for the early Triassic total annealing of those samples lacking connectivity with the fault.The above arguments are supported by thermal modeling results.

A Compilation of New and Existing Thermochronology Data Concerning the Lhasa Terrane Combined with a Geological Synthesis of the Area

The history and geodynamic mechanisms of Cenozoic exhumation and denudation of the Lhasa terrane(LT),southern Tibetan Plateau, remain poorly constrained. Most previous studies investigating the exhumation of the LT have relied on extrapolating interpretations based on a few well-studied but small areas, which inevitably introduce bias. Here,our compilation of new and published thermochronologic ages are plotted against latitude, longitude, and elevation, to illustrate the distribution of cooling ages across broad regions of the LT. Primary results reveal that(1) the north LT experienced significant exhumation during 80–40 Ma;(2) compared with north LT, exhumation and erosion in the south LT continued after ~40 Ma;and(3) N–S striking rifting, E–W striking river incision, and thrusts led to continued local denudation of the south LT between 20–5 Ma.

An apatite U-Pb thermal history map for the northern Gawler Craton,South Australia

Apatite U-Pb thermochronology was applied to granitoid basement samples across the northern Gawler Craton to unravel the Proterozoic, post-orogenic, cooling history and to examine the role of major fault zones during cooling. Our observations indicate that cooling following the ~2500 Ma Sleaford Orogeny and ~1700 Ma Kimban Orogeny is restricted to the Christie and Wilgena Domains of the central northern Gawler Craton. The northern Gawler Craton mainly records post-Hiltaba Event(~1590 Ma) U-Pb cooling ages. Cooling following the ~1560 Ma Kararan Orogeny is preserved within the Coober Pedy Ridge,Nawa Domain and along major shear zones within the south-western Fowler Domain. The Nawa Domain samples preserve U-Pb cooling ages that are >150 Ma younger than the samples within the Coober Pedy Ridge and Fowler Domain, indicating that later(~1300 Ma) fault movement within the Nawa Domain facilitated cooling of these samples, caused by arc collision in the Madura Province of eastern Western Australia. When compared to^(40)Ar/^(39) Ar from muscovite, biotite and hornblende, our new apatite U-Pb ages correlate well, particularly in regions of higher data density. Our data also preserve a progressive younging of U-Pb ages from the nucleus of the craton to the periphery with a stark contrast in U-Pb ages across major structures such as the Karari Shear Zone and the Southern Overthrust, which indicates the timing of reactivation of these major crustal structures. Although this interpolation was based solely on thermochronological data and did not take into account structural or other geological data, these maps are consistent with the structural architecture of the Gawler Craton and reveal the thermal footprint of known tectonic and magmatic events in the Gawler Craton.

Continental accretion and incremental deformation in the thermochronologic evolution of the Lesser Caucasus

Apatite fission-track analysis and thermochronologic statistical modeling of Precambrian-Oligocenc plutonic and metamorphic rocks from the Lesser Caucasus resolve two discrete cooling episodes.Cooling occurred during incremental crustal shortening due to obduction and continental accretion along the margins of the northern branch of the Neotethys.(1)The thermochronometric record of a Late Cretaceous(Turonian-Maastrichtian)cooling/exhumation event,coeval to widespread ophiolite obduction,is still present only in a relatively small area of the upper plate of the Amasia-Sevan-Akera(ASA)suture zone,i.e.the suture marking the final closure of the northern Neotethys during the Paleogene.Such area has not been affected by significant later exhumation.(2)Rapid cooling/exhumation occurred in the Early-Middle Miocene in both the lower and upper plates of the ASA suture zone,obscuring previous thermochronologic signatures over most of the study area.Miocene contractional reactivation of the ASA suture zone occurred contemporaneously with the main phase of shortening and exhumation along the Bitlis suture zone marking the closure of the southern branch of the Neotethys and the ensuing ArabiaEurasia collision.Miocene collisional stress from the Bitlis suture zone was transmitted northward across the Anatolian hinterland,which was left relatively undeformed,and focused along preexisting structural discontinuities such as the eastern Pontides and the ASA suture zone.

New approach to resolve the amount of Quaternary uplift and associated denudation of the mountain ranges in the Japanese Islands

Low-temperature thermochronology is a widely used tool for revealing denudation histories of mountain ranges. Although this technique has been applied mainly to continental orogens, such as the European Alps, Himalayas, and Andes, recent technological development of low-temperature thermochronology has made it applicable to a wider variety of mountain ranges with various sizes and tectonic histories. The Japanese Islands comprise young and active island arcs, where an early stage of mountain range formation is observed. Numerous attempts have been made to constrain the uplift and denudation histories of the mountains in the Japanese Islands using geologic, geomorphologic, or geodetic methods. However, the number of thermochronometric attempts has been limited primarily due to the small amount of total denudation since the initiation of the uplift. In this review paper, we introduce the tectonic and geomorphic settings of the mountain ranges in the Japanese Islands, and discuss previous attempts to estimate uplift or denudation of the Japanese mountains using methods other than ther- mochronology. Furthermore, we discuss problems of the thermochronometric applications in revealing denudation histories of the Japanese mountains. Finally, we present a case study of the Kiso Range in central Japan and discuss the current effectiveness and applicability of low-temperature thermochronology to the Japanese mountainous areas.

Cenozoic Exhumation of Larsemann Hills,East Antarctica:Evidence from Apatite Fission-track Thermochronology

Does Cenozoic exhumation occur in the Larsemann Hills, East Antarctica？ In the present paper, we conducted an apatite fission-track thermochronologic study across the Larsemann Hills of East Antarctica. Our work reveals a Cenozoic exhumation event at 49.8 ± 12 Ma, which we interpret to be a result of exhumation caused by crustal extension. Within the uncertainty of our age determination, the timing of extension in East Antarctica determined by our study is coeval with the onset time of rifting in West Antarctica at c.55 Ma. The apatite fission-track cooling ages vary systematically in space, indicating a coherent block rotation of the Larsemann Hills region from c.50 Ma to c.10 Ma. This pattern of block tilting was locally disrupted by normal faulting along the Larsemann Hills detachment fault at c.5.4 Ma. The regional extension in the Larsemann Hills, East Antarctica was the result of tectonic evolution in this area, and may be related to the global extension. Through the discussion of Pan-Gondwanaland movement, and Mesozoic and Cenozoic extensions in West and East Antarctica and adjacent areas, we suggest that the protracted Cenozoic cooling over the Larsemann Hills area was caused by extensional tectonics related to separation and formation of the India Ocean at the time of Gondwanaland breakup.

Study on Late Cretaceous-Cenozoic exhumation of the Yanji area,NE China: insights from low-temperature thermochronology

The Yanji area,northeastern China,a part of the orogenic collage between the North China Block in the south and the Jiamusi-Khanka Massifs in the northeast,is the most likely location where the Pacific Plate subduction・related magmatic activities and subsequent exhumation processes occurred.Here,we report new low-temperature thermochronology of apatite and zircon data from the granitoid samples in the Yanji area.The exhumation rates of Tianfozhishan,Yanji area,were〜0.049 and〜0.073 mm/year,interpreted from the elevations and apatite and zircon fission track ages,respectively.The exhumation,integrated with the geological setting,suggested that the paleogeothermal gradient of the Tianfozhishan,even extending to the Yanji area,was possibly to be greater than 35℃/km in the Late Cretaceous.The thermal history modeling of the data indicates a basically similar pattern,but the various timing for different samples between the Oligocene-Early Miocene and the Middle Miocene in the Yanji area.We hence conclude that a fourstages of cooling,from〜6.7℃/Ma(during the Late Cretaceous),to〜0.8℃/Ma(during the Late Cretaceous to the Oligocene-Early Miocene),then to〜2-3℃/Ma with varied styles(between the Oligocene-Early Miocene and the Middle Miocene),and finally to<0.2℃/Ma(since the Middle Miocene),has taken place through the exhumation of the Yanji area.The maximum exhumation is>3 km under a reasonable paleogeothermal gradient(>35℃/km),speculated from the possible exhumation rate of Tianfozhishan.Combined with the tectonic setting,this exhumation,including two stages of pronounced tectonic uplift and denudation and two stages of weak exhumation driven by the low regional erosion rate,is possibly related to the subduction of the Pacific Plate beneath the Eurasian Plate since the Late Cretaceous.This study used more robust evidence to propose higher paleogeothermal gradient(>35℃/km),reflecting exhumation of>3 km in the Yanji area since the Late Cretaceous.

Characteristics of helium accumulation in the Guanzhong Basin, China

Guanzhong Basin is located in the transitional zone between the Qinling orogenic belt and the Ordos plateau. Analyses of drill and geothermal wells depict that the Guanzhong Basin has abundant gas, and its major source rocks are the U-rich granites. In this study, the granitoid intrusive samples were collected from the Huashan, Baoji, Muhuguan rocks in Guanzhong Basin. A micro laser Raman spectrum examination was used to measure the composition of inclusion in the granite quartz fissures. The results depict that the inclusions include both gas-liquid and H2O-NaCl-CO2 inclusions and that their composition primarily includes H2O and CO2, with small amounts of CH4, H2 and H2S. These inclusions can be classified into nearly-primary, early secondary, and late secondary inclusions, which have homogenization temperatures of greater than 430℃, 330-370℃ and 170-230℃, respectively, based on the inclusion measurements. Additionally, the apatite fission-track investigations of six samples, which were collected from the granites at Huashan, Baoji rocks and the southern margin of Muhuguan along with the Cretaceous Sigou Formation sandstones that are located in the northwestern margin of the Guanzhong Basin reveal that the northern Guanzhong Basin began to receive deposits as early as 84 -69 Ma. This period was accompanied by the rapid uplift of the Qinling orogenic belt, which was followed by an uplift of the southern basin margin and the Qinling orogenic belt from 44-28 Ma. The authors obtained an age histogram and a probability density distribution of three sample points. The results show that the age spectra of the zircons in the Cretaceous Sigou Formation sandstones can be divided into four tectonic events. Combined with the ages of apatite fission tracks and zircon, the Guanzhong Basin has experienced five tectonic stages as follows: 28-84 Ma, 170-260 Ma, 280-510 Ma, 610-1200 Ma, and 1210-2870 Ma. Using the thermal chronology constraints, inclusion composition analyses, which include the homogenization temperature measurements, and regional burial history, this paper conclude that the early secondary inclusions are primarily composed of CO2 and N2, whereas the late secondary inclusions are composed of CH4. Furthermore, this paper identify two periods of reservoir accumulation, out of which the later period is assumed to be the main accumulation period. Therefore, the period of the formation of the late secondary inclusion in the Guanzhong Basin and the Miocene era is observed to overlap with the main helium reservoir accumulation period.

Assessing volcanic origins within detrital zircon populations——A case study from the Mesozoic non-volcanic margin of southern Australia

Detrital zircon U/Pb geochronology is a common tool used to resolve stratigraphic questions,inform basin evolution and constrain regional geological histories.In favourable circumstances,detrital zircon populations can contain a concomitant volcanic contribution that provides constraints on the age of deposition.However,for non-volcanic settings,proving isolated detrital zircon grains are from contemporaneous and potentially remote volcanism is challenging.Here we use same grain(U-Th)/He thermochronology coupled with U/Pb geochronology to identify detrital zircon grains of contemporary volcanic origin.(U-Th)/He ages from Cretaceous zircon grains in southern Australia define a single population with a weighted mean age of 104±6.1 Ma.indistinguishable from zircon U/Pb geochronology and palynology(~104.0-107.5 Ma).Detrital zircon trace-element geochemistry is consistent with a continental signature for parent rocks and coupled with detrital grain ages,supports derivation from a>2000 km distant early-to mid-Cretaceous Whitsunday Volcanic Province in eastern Australia.Thus,integration of biostratigraphy,single-grain zircon double-dating(geochronology and thermochronology)and grain geochemistry enhances fingerprinting of zircon source region and transport history.A distal volcanic source and rapid continental-scale transport to southern Australia is supported here.

Apatite Fission-Track Datings on Hercynian Granites from Rehamna and Jebilet Massifs(Western Meseta,Morocco):Paleogeographic Implications and Interpretation of AFT Age Discrepancies

This work is based on apatite fission-track analysis of samples(mostly granites)from the basement of the Cretaceous-Tertiary Phosphate and Ganntour Plateaus, exposed in the Jebilet and Rehamna massifs (Western Meseta,Morocco).This basement