The paleo-geothermal gradient is a crucial parameter for converting the thermal history to the exhumation history. However, the precise estimation of this parameter has been a challenge. This paper presents a simple two-step method to model the paleo-geothermal gradient using low-temperature thermochronology. (1) It uses the Monte Carlo approach to generate thermal histories in a vertical section randomly and calculates the entire thermal history within the goodness-of-fit thresholds based on different paleo-geothermal gradients. (2) It selects the optimum paleo-geothermal gradient by comparing the entire thermal history within different goodness-of-fit thresholds. We validated the method with apatite (U-Th)/He and fission track data collected from two drill cores in the Haiyuan-Liupanshan region. The result revealed that the best-fit paleo-geothermal gradient was ∼42 °C/km during the Early Cretaceous–Miocene and has decreased rapidly to 20 °C/km since ∼10 Ma. The crust thickening in the study area may explain the rapid reduction in the paleo-geothermal gradient since ∼10 Ma. Our results are consistent with earlier studies in the region, suggesting that our simple and more intuitive approach provides an alternative method for paleo-geothermal gradient modeling.

The East Asian monsoon is the largest periodic airflow on Earth and significantly affects the climate of East Asia. However, considerable controversy exists about the onset timing of the East Asian monsoon. As one of the southern barriers blocking the northward movement of the warm and humid airflow, the Nanling Range has likely recorded key topographic information related to the East Asian monsoon onset and development. We used apatite and zircon (U-Th)/He data obtained from the Shaoguan-Guidong horizontal cross-section to reconstruct the two-dimensional (2-D) paleotopography of the Nanling Range on a long-term scale. Four vertical profiles in Shulouqiu, Erjian, Sanfenshi, and Leiwangdian were used to constrain the exhumation history of the Nanling Range. The result revealed the following: 1) The drainage divide began to move from south to north at 80 Ma. At 80 Ma, the south segment of the cross-section reached a peak elevation of -3.6 km. The asymmetric topography experienced a rapid elevation (and relief) decrease from 80 Ma to 40-30 Ma. The four vertical profiles also experienced increased cooling and high exhumation rates from 100 Ma to 40-30 Ma. 2) The south segment experienced more rapid exhumation than the north segment from 80 Ma to 40-30 Ma. The rapid exhumation of the south segment during the Late Cretaceous-Paleocene is probably related to the activity of the Nanxiong Fault, and the rapid exhumation of the south segment during the Eocene probably results from the onset of the East Asian Monsoon.

The coastal mountain system (CMS) of southeastern China has been a natural place to study paleotopographic changes primarily due to its marked topographical contrast since the Late Cretaceous. For a quantitative reconstruction of the paleotopographic evolution of the CMS, this paper provides key information from along the Ningde-Jianyang and Huilai-Longchuan cross-sections using apatite (U-Th)/He (AHe) and zircon (U-Th)/He (ZHe) data combined with thermal history and paleotopographic modeling. For the Ningde-Jianyang section, the AHe dates are in the range of 44.3-70.8 Ma, and the ZHe dates are between 58.5 and 102.9 Ma. For the Hui-lai-Longchuan section, the resulting AHe dates are in the range of 37.9-73.8 Ma, and ZHe dates are between 65.5 and 119.7 Ma. The modeling results suggest that: 1) the CMS had an asymmetric topography during the Late Cretaceous with the SE segment being significantly higher (peak elevation = 3.8 km) than the NW segment (peak elevation =-2 km). The marked decreases in elevation and relief of the CMS occurred during 80-40 Ma, fol-lowed by relatively minor topographic changes since-40-30 Ma; 2) The SE segment of the southern CMS experienced significantly faster exhumation (-0.44 km/Myr) than northern CMS (0.16 km/Myr) during 70-60 Ma, which was probably related to thinning of the crust and orogenic collapse linked to the initial-rifting of the South China Sea; 3) The SE segment of southern CMS experienced slower exhumation than northern CMS during 60-40 Ma, likely resulting from the lower elevations in the southern CMS than in the northern CMS during 60-40 Ma.

Thermal history reconstruction of the deep and ancient strata (Pre-Silurian) in the Tarim Basin is always difficult due to the lack of effective paleo-thermal indicators. This study provides a new strategy for thermal history reconstruction of the Tarim Basin with the zircon (U-Th)/He thermochronology. The obvious dispersion of the single-grain zircon (U-Th)/He ages for all the clastic rocks in the Tarim Basin reflects the complex and protracted thermal histories. The combination of forward and inverse modeling revealed that the Neoproterozoic rocks from the Kalpin and Bachu Uplifts experienced four rapid cooling events beginning in the Late Ordovician, Late Carboniferous, Late Triassic and Early Miocene, while the Silurian rocks in the eastern Tarim Basin just expe-rienced the Late Carboniferous and Late Cretaceous cooling events. In addition, these rocks experienced several thermal events with the highest temperature of 160-180 degrees C (a precision of 5-10 degrees C). The unique thermal his-tories in the Tabei Uplift and Shunbei area was suitable for the crude oil preservation. This study not only promotes the application of the zircon (U-Th)/He thermochronology in sedimentary basins but also clarify the thermal evolution process of the ancient strata in the Tarim Basin, which plays an important role in determining the deeper source rocks maturation phase and hydrocarbon occurrence state.

Cenozoic exhumation in the Tianshan is controlled by a complex interaction between tectonics and climate. However, the timing and magnitude of exhumation of the Tianshan and its contribution to climate change in Central Asia remains debated. In this study, we report new apatite fission track and (U‐Th)/He ages for granite samples from the roof of the South Tianshan that are significantly younger than those published for other parts of the South Tianshan. Inverse and forward modeling reveals two phases of accelerated cooling at 10∼6 Ma and since ∼3 Ma, which can be linked to (1) the reactivation of strike‐slip faults and hot asthenospheric upwelling during India‐Eurasia convergence and (2) the interplay between tectonics and glaciation, respectively. The 10∼6 Ma exhumation phase further corresponds to the timing of climate change, suggesting that this exhumation phase significantly contributed to the enhanced aridification of the Tarim Basin.

The mineralogical characterization of dark green cements of intraclasts and their host sandstones, developed using optical petrography, X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) and organic petrography, provides new insights about the diagenetic evolution and depositional conditions of the late Oligocene-middle Miocene Amaga Formation, northwestern Colombia. Dark green intraclasts are found in medium-grained, slightly feldspathic sandstones, in which the main authigenic mineral is pyrite that formed during a mesogenetic (burial diagenesis) stage. The host sandstones of the dark green intraclasts were deposited in a meandering river environment and are related to point bar deposits over swampy areas. These strata are medium-grained quartzose sandstones cemented by ankerite as a product of replacement of early calcite through hydrothermal alteration. Solid hydrocarbons analysis together with new low-tempereture thermocronology apatite (U-Th)/He data, available apatite fission-track (AFT), zircon fission-track (ZFT) and vitrinite reflectance (%Ro) data, indicate maximum burial temperatures of ca., 100 degrees C for the deeper parts of the basin. Solid hydrocarbons were emplaced in the late stages of the diagenetic history and occur in a porous system where fractures played an important role. They constitute the first evidence of migration and accumulation of hydrocarbons in the Amaga Basin. However, the latest event of fracturing during a major cooling event associated with basin inversion at ca., 4 Ma, caused complete hydrocarbon biodegradation and seepage, and increased the effect of meteoric water inflow during the telogenetic stage.

Cenozoic exhumation in the Tianshan is controlled by a complex interaction between tectonics and climate. However, the timing and magnitude of exhumation of the Tianshan and its contribution to climate change in Central Asia remains debated. In this study, we report new apatite fission track and (U-Th)/He ages for granite samples from the roof of the South Tianshan that are significantly younger than those published for other parts of the South Tianshan. Inverse and forward modeling reveals two phases of accelerated cooling at 10 similar to 6 Ma and since similar to 3 Ma, which can be linked to (1) the reactivation of strike-slip faults and hot asthenospheric upwelling during India-Eurasia convergence and (2) the interplay between tectonics and glaciation, respectively. The 10 similar to 6 Ma exhumation phase further corresponds to the timing of climate change, suggesting that this exhumation phase significantly contributed to the enhanced aridification of the Tarim Basin. Plain Language Summary The tectonic uplift of the Mountains is closely related to climate change in nearby areas, e.g. the uplifting of the Tibetan Plateau plays an important on the aridification of the Tarim Basin since the Cenozoic. This study reported a new set of low-temperature thermochronological data from the high-elevation area of the Tianshan. They revealed the rapid exhumation of the central Chinese South Tianshan during 10.0-6.0 Ma, simultaneous with the enhanced aridification of the Tarim Basin. Therefore, we speculated that the uplift of the central South Tianshan have effectively blocked the humid westerlies from the Atlantic and Indian Oceans to enter the Tarim Basin and enhanced the aridification in the Tarim Basin during the late Miocene.

The Mufushan massif, as continental intra-plate magmatites located in the Jiangnan-Xuefeng orogenic belt of the South China. The Mufushan massif constitutes the largest Mesozoic intrusive complex, intruded the Mesoproterozoic Lengjiaxi Formation. Multiple geochronometric dating was used to reconstruct their evolution from emplacement to exhumation. The Mufushan granitoids were emplaced at ∼150 Ma (U-Pb zircon) as post-orogenic magmatites contributing to Triassic crustal thickening. Onset of regional extension at ∼128 Ma (40Ar/39Ar white mica and biotite) manifests a tectonic regime switch. Intense exhumation prior to ∼55 Ma was followed by slow denudation and peneplanation for the next 37 Ma (∼55’18 Ma). Accelerated cooling since ∼18 Ma may have been caused by a far-field effect of the collision between India-Asia Plate or the Pacific-Plate subduction. Through a multi-geochronometric approach, this study provides a new comprehensive model for the cause of the intra-plate magmatism formation in the South China, and also established a reliable geochronological framework of the post-orogenic tectonic evolutions of the Jiangnan-Xuefeng orogenic belt.

This paper presents an approach to improve the previously proposed 2-D topography modeling (Ding et al., 2019) that is primarily based on inversion of low-temperature thermochronological data. The new approach requires thermochronological data from both horizontal transect and vertical profiles to yield a more comprehensive modeling of topographic evolution. This modeling allows for (1) reconstruction of paleotopography evolution and (2) calculation of spatial distribution of paleo-geothermal gradients over time; therefore, it is possible to deduce more reliable exhumation histories even for non-steady state topographic evolution. The deduced exhumation histories are used to re-evaluate the topography modeling results. This approach when applied to the Dabie orogen in Eastern China suggests an uneven topographic evolution along the Xishui-Lu'an section and comparable exhumation histories for the Meichuan, the Tianzhushan, the Mingtangshan and the Tiantangzhai vertical profiles since the Late Cretaceous. The modeling results suggest that the location of the highest elevation in the NE-SW transect has been almost identical for the last 80 Ma although the elevation of the peak has reduced by -3.3 km over the same period. The elevation reduction in the NE segment during 70-40 Ma is caused by extensional activity of the Xiaotian-Mozitan fault. The elevation reduction in the SW segment during 50-30 Ma is probably related to climate change, where the Paleogene topography change in the Dabie orogen played an important role introducing humid and warm air from the Pacific Ocean. (C) 2020 Elsevier B.V. All rights reserved.

The Kalpin fold-and-thrust belt (FTB) was active during the Cenozoic and accommodated crustal shortening between the Tian Shan and Tarim Basin. To constrain the timing of thrusting in the Yimugantawu and Kepingtag thrust sheets from north to south in the central area of the Kalpin FTB, we performed apatite fission track (AFT) and apatite (U-Th)/He (AHe) dating, as well as sandbox experiments. The AFT central ages of the Yimugantawu and Kepingtag thrust sheets range from 93.0 to 148.7 Ma. Single grain AHe ages of the Kepingtag thrust sheet (10.7-27.1 Ma) are younger than those of the Yimugantawu thrust sheet (15.1-82.5 Ma), indicating a southward propagation of the Cenozoic deformation. Combined inverse and forward thermal modeling suggest that the Yimugantawu and Kepingtag thrust sheets underwent initial cooling and deformation at 25-20 Ma and 15-10 Ma, respectively. The sandbox experiments also suggest that the Yimugantawu thrust sheet underwent deformation before the Kepingtag thrust sheet was activated, confirming the sequence revealed by low-T thermochronology. This study provides new insights into the timing of deformation at the northern margin of the Tarim Basin, which can significantly enhance understanding of the tectonic evolution of Central Asia.

New geochronologic, thermochronologic, and geomorphometric landscape analyses were performed to discriminate the relationships between tectonics and geomorphology in the northwestern portion of the Central Cordillera, Northern Andes (Colombia). This segment of the Andean belt includes two contrasting geomorphic domains, namely the Antioqueno Plateau (AP) and the Cauca River Canyon (CRC). At present, these domains are connected fluvially by the San Andres River Catchment (SARC) and disrupted structurally by the Espiritu Santo Fault (ESF). Zircon U/Pb ages indicate Triassic metamorphism and Late Cretaceous magmatism, suggesting the absence of major Cenozoic thermal events related to magmato-metamorphism that could affect low-temperature thermochronology datasets. New (U-Th)/He data were collected along vertical profiles and modeled numerically using HefTy (R) and Age2Edot (R) software. The modeling results suggest a continuum rapid cooling event during the Paleocene- Eocene associated with erosional exhumation. Erosion rates derived from relationships between zircon (U-Th)/He ages and elevation, are approximately 0.2-0.6 km/Ma and therefore slightly lower than estimates derived from inverse thermal modeling (ca. 0.6-0.9 km/Ma), Differences between observed and estimated exhumation rates could be due to differential surface uplift and reactivation of the ESF. Such reactivation produced systematically younger (U-Th)/He ages near faulted, popped-up blocks, suggesting active deformation since the Oligocene-Early Miocene. Geomorphometric parameterization, applied to both the AP and the CRC, suggests a complex mixture of processes such as differential surface uplift, landscape rejuvenation, relief inversion, preservation of relict landscapes, and reorganization of the fluvial system. Our investigation documents: i) a phase of rapid exhumation during the Late Paleocene-Eocene that favored posterior development of low relief surfaces; ii) post-Eocene ESF reactivation, differential uplift, and relict landscape preservation on the AP; and iii) post-Oligocene landscape rejuvenation and fluvial capture of the SARC by upward progression of the erosional wave-front through the CRC. (C) 2019 Elsevier B.V. All rights reserved.

Landscapes in mountain belts evolve through complex feedback mechanisms between internal and external processes. Modern orogenic belts, such as the Andes, are the result of millions of years of continuing internal and external processes. Therefore, mountain ranges are rich repositories of geomorphic and tectonic information. Established techniques in low temperature thermochronology (LTTC), e.g., fission-track and (U-Th)/He dating, present novel opportunities to quantitatively explore key morphotectonic processes in the upper crust, e.g., the cooling of rocks as they move toward the Earth's surface during exhumation, via erosion, normal faulting, and/or crustal thinning. We address the Late Mesozoic-Cenozoic morphotectonic and orogenic history of the Northern Andes of Colombia using detailed compilations and analysis of existing LTTC datasets, in an effort to define the spatial distribution, timing, and magnitude of the main orogenic phases in the region, while providing an up-to-date morphotectonic picture of the Northern Andes.

The Yadong area, at the geographic boundary between the Central and Eastern Himalaya, contains the largest along-strike structural discontinuity in the Himalaya. We conducted zircon fission track (ZFT)and apatite (U–Th)/He (AHe) dating along a 50 km transect of the Greater Himalaya Sequence (GHS) to investigate the cooling and exhumation of this structural discontinuity. New ZFT (14.0–8.2 Ma) and AHe (11.1–4.2 Ma) data suggest fast tectonic exhumation of the GHS in the Middle Miocene. After this pulse of rapid exhumation, the area remained in a long-term slower and steady state of exhumation ( c. 0.32 km/Ma since c. 7.7 Ma). New stream topographic analysis also confirms this slow surface erosion in the hinterlands whereas the frontal range underwent enhanced erosion, possibly due to southward upthrusting along the Main Boundary Thrust and Main Frontal Thrust. Our data underline distinctive exhumation patterns between the Eastern and Central Himalaya and suggest that exhumation of the Himalaya was primarily driven by tectonics associated with the underlying Main Himalaya Thrust (MHT). The long-term, slow and steady exhumation in the Yadong area and the Eastern Himalaya hinterland since the Late Neogene is consistent with the gentle dip of the MHT supporting a slab tear of the subducting Indian Plate.

Introduction: Single-grain (U-Th)/He ages from meteorites are commonly scattered, making it difficult to extract meaningful information from the data. The unresolved question is how the samples from a single meteorite rock chip, typically less than 1-2 cm in linear dimensions, yielded scattered ages even though they are expected to have experienced the same thermal history. In this study, we present single-grain (UTh)/He ages from two acapulcoites of EET14074 and TIL07012, and attempt to interpret the resulting ages using a simple He diffusion model combined with morphological characteristics of the samples. Results: For EET14074, the alpha recoiluncorrected (U-Th)/He ages obtained from 37 phosphate aggregates are widely scattered from 116.8 Ma ± 145.7 (1σ) Ma to 4212 Ma ± 1089 Ma (Fig. 1). Two batches of the same size samples, analyzed to check the reproducibility, yielded indistinguishable results.

Multiple phases of extension and contraction in orogens can produce relatively complicated thermal histories for sedimentary basins as recorded by thermochronological datasets. This makes it difficult to determine which tectonic events had the most impact on the thermal state, and were drivers of exhumation, of the upper crust. In this study, apatite and zircon (U-Th)/He data obtained from five drill core samples (Campaspe DDH-1) from the Drummond Basin are used to construct a continuous, post-depositional thermal history of this Late Devonian-Early Carboniferous rift basin. Detrital zircon U/Pb ages indicate a maximum depositional age of similar to 340 Ma for the sampled formations, however, most apatite (U-Th)/He (AHe) analyses yielded apparent ages of 30-100 Ma (n = 35) and zircon (U-Th)/He (ZHe) analyses gave ages of 200-340 Ma (n = 67). Zircon (U-Th)/(He-Pb) double dating yielded no correlation between U/Pb and ZHe ages, with all the ZHe ages younger than depositional age. These data indicate disturbance of the ZHe and AHe systems after deposition. Inverse thermal history modeling using the QTQt and HeFTy codes suggests the samples experienced two post-depositional heating-cooling cycles: (1) rapid heating to similar to 150-195 *DEG;C at similar to 300 Ma was followed by rapid cooling to near-surface temperatures of similar to 50(+50)/(-30) *DEG;C between 270 and 240 Ma, and (2) gradual heating until the Early Cretaceous, when temperatures increased to similar to 105(+15)/(-10) *DEG;C followed by rapid cooling beginning similar to 90 Ma. We relate the similar to 300 Ma heating to the Kennedy-Connors-Auburn silicic large igneous province, revealing that major regional igneous events can significantly perturb a basin thermal history. In contrast, the slow temperature increase between similar to 270 and 100 Ma is related to progressive burial by overlying sediments of the Galilee and Great Australian basins. Finally, rapid cooling beginning similar to 90 Ma was synchronous with rift margin exhumation.

We review the geology of the Gyeonggi Massif, Gyeonggi Marginal Belt, and Taebaeksan Basin of the Korean Peninsula, which are relevant to the 2018 Winter Olympic sites. Neoarchaean-Palaeoproterozoic gneisses and schists of the Gyeonggi Massif underwent two distinct collisional orogenies at the Palaeoproterozoic (1.88-1.85Ga) and Triassic (245-230Ma). These basement rocks are structurally overlain by a suite of Mesoproterozoic to Early Permian supracrustal rocks of the Gyeonggi Marginal Belt, consisting primarily of medium-pressure schists and amphibolites metamorphosed at 270-250Ma. In contrast, sedimentary successions in the Taebaeksan Basin, commonly fossiliferous, consist primarily of Early Cambrian-Middle Ordovician Joseon Supergroup and Late Carboniferous-Early Triassic Pyeongan Supergroup. The Great Hiatus' between the two supergroups is characteristic for the North China Craton. The marked contrast in tectonometamorphic evolution between the Taebaeksan Basin and Gyeonggi Marginal Belt suggests an existence of major suture in-between, which is most likely produced by the Permian-Triassic continental collision between the North and South China cratons. Finally, recent tectonics of the Korean Peninsula is governed by the opening of East Sea/Sea of Japan during the Late Oligocene-Early Miocene. This back-arc rifting event has resulted in an exhumation of the Taebaek Mountain Range, estimated to be 22 +/- 3Ma on the basis of apatite (U-Th)/He ages. Thus, high topography in the 2018 Winter Olympic sites is the consequence of Tertiary tectonics associated with the opening of a back-arc basin.