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The Daba Shan orocline is located at the northeastern margin of the Sichuan Basin and has been inferred as a foreland thrust-fold belt of the Qinling Orogen since the Late Triassic. A complete understanding of rock exhumation history is critical to elucidate how and when this typical orocline structure is developed. Detrital apatite fission-track dating of modern river sands is employed to reveal the regional exhumation history of the Daba Shan orocline. Four age peaks are identified and interpreted as the results of tectonic exhumation. Two older age peaks at ∼150–140 and ∼116–86 Ma are agreement with two main shortening deformation episodes of the Yanshanian Movement in the eastern China. The other two younger age peaks at ∼69 and ∼37 Ma support that the Daba Shan was reactivated by the Late Cretaceous to Cenozoic deformation which were likely related to the subduction of the Pacific Ocean and eastward growth of the Tibetan Plateau, respectively. It is worth noting that in contrast to the ∼150–140 Ma rapid rock uplift and exhumation, the Middle Cretaceous exhumation (∼116–86 Ma) shifted southward and continued to spread to southern tips of the Daba Shan. These exhumation variations in temporal and spatial allow a southward thrust deformation with piggyback style during the Yanshanian. [ABSTRACT FROM AUTHOR]

This study investigates eastward-moving summer heavy rainfall events in the lower reaches of the Yangtze River (LRYR), which are associated with the Tibetan Plateau (TP) vortices. On the basis of rainfall data from gauges and additional atmospheric data from ERA-Interim, the dynamic and thermodynamic effects of moisture transport and diabatic heating are estimated to determine the physical mechanisms that support the eastward-moving heavy rainfall events. As the rainband moves eastward, it is accompanied by anomalous cyclonic circulation in the upper and middle troposphere and enhanced vertical motion throughout the troposphere. In particular, the rainfall region is located in the fore of the upperlevel trough, which is ideal for baroclinic organization of the convective system and further development of the eastwardmoving vortex. The large atmospheric apparent heat source (Q1) also contributes for lifting the lower-level air into the upper atmosphere and for enhancing the low-level convective motion and convergence during the heavy rainfall process. Piecewise potential vorticity inversion further verifies the crucial role that the diabatic heating played in developing the anomalous geopotential height favorable for the enhanced rainfall. The combined action of the dynamic and thermodynamic processes, as well as the rich moisture supply from the seas, synergistically sustained and enhanced the eastwardmoving rainfall. [ABSTRACT FROM AUTHOR]

The Upper Weihe River (UP‐WHR) basin is located along the northeastern Tibetan Plateau. With the northeastward expansion of the Tibetan Plateau since the late Cenozoic, it has involved foreland propagation and undergone obvious surface uplift. In order to determine the latest differential rock uplift and river incision, longitudinal profiles for 12 major tributaries of the UP‐WHR were extracted. Among them, 11 tributaries display uneven profiles with “slope‐break” knickpoints, suggesting that they are in a transient state and that the change in base level caused by tectonic forces may respond to the channel evolution. In addition, channel steepness index (ksn) was calculated to detect the spatial variations of the rock uplift rate. The results show that the north margin of West Qinling (WQL) and the south Liupan Shan (LPS) areas have a high uplift rate. Reconstruction of the paleochannel indicates that the Weihe River has an average incision of 354 ± 130 m since it formed, and the south tributaries have a higher incision of 144 ± 25 m than the north. An average river erosion rate of 0.25–0.3 m/ka was estimated, the WQL has a higher erosion rate of 0.1–0.12 m/ka than Longzhong Basin and the south LPS. This uplift and river incision can be correlated to the northeastward growth of the Tibetan Plateau since the late Cenozoic. [ABSTRACT FROM AUTHOR]

Mutational changes in p53 correlate well with tumorigenesis. Remarkably, however, relatively little is known about the role that p53 variations may play in environmental adaptation. Here we report that codon asparagine-104 (104N) and glutamic acid-104 (104E), respectively, of the p53 gene in the wild zokor (Myospalax baileyi) and root vole (Microtus oeconomus) are adaptively variable, meeting the environmental stresses of the Tibetan plateau. They differ from serine-104 (104S) seen in other rodents, including the lowland subterranean zokor Myospalax cansus, and from serine 106 (106S) in humans. Based on site-directed mutational analysis in human cell lines, the codon 104N variation in M. baileyi is responsible for the adaptive balance of the transactivation of apoptotic genes under hypoxia, cold, and acidic stresses. The 104E p53 variant in Microtus oeconomus suppresses apoptotic gene transactivation and cell apoptosis. Neither 104N nor 104E affects the cell-cycle genes. We propose that these variations in p53 codon 104 are an outcome of environmental adaptation and evolutionary selection that enhance cellular strategies for surviving the environmental stresses of hypoxia and cold (in M. baileyi and M. oeconomus) and hypercapnia (in M. baileyi) in the stressful environments of the Qinghai-Tibet plateau. [ABSTRACT FROM AUTHOR]

Background and aims: The warming of the planet in recent decades has caused rapid, widespread permafrost degradation on the Qinghai-Tibet Plateau. These changes may significantly affect soil moisture content and nutrient supply, thereby affecting ecosystem structure and function. This study aimed to describe the dynamic changes in thaw depth, assess the relationship between thaw depth and soil moisture content, and analyze the changes in species composition and water-use efficiency in response to permafrost degradation. Methods: We surveyed species composition, thaw depth, ground temperature, soil moisture, nutrient content, and foliar stable carbon isotope compositions to gain insights into the response of alpine grassland ecosystems to permafrost degradation on the Qinghai-Tibet Plateau. Results: Moisture content of the surface layer decreased with increasing thaw depth. The correlation between thaw depth and surface soil moisture content was strongest in June and decreased in July and August. The strongest correlation occurred at a depth of 20 cm to 30 cm. The dominant species shifted from Cyperaceae in alpine meadow to mesoxerophytes in alpine steppe before finally shifting to xerophytes in alpine desert steppe. Thaw depth correlation was significantly negative with organic C content ( r = −0.49, P < 0.05) and with total N content ( r = −0.62, P < 0.01). The leaf δC of Carex moorcroftii increased with increasing thaw depth and followed a linear relationship ( R = 0.85, P = 0.008). Conclusions: Permafrost degradation decreases surface soil moisture and soil nutrient supply capacity. Increasing permafrost degradation decreases the number of plant families and species, with hygrophytes and mesophytes gradually replaced by mesoxerophytes and xerophytes. The water-use efficiency of plants improved in response to increasing water stress as surface layers dried during permafrost degradation. Permafrost on the Qinghai-Tibetan Plateau is expected to further degrade as global warming worsens. Therefore, more attention should be dedicated to the response of alpine ecosystems during permafrost degradation. [ABSTRACT FROM AUTHOR]

The ecosystems of the Tibetan Plateau (TP) provide multiple important ecosystem services that benefit both local populations and those beyond, such as through climate regulation services on precipitation for East Asia and China. However, the precipitation regulation service of the TP ecosystems for supplying moisture and maintaining precipitation is yet to be evaluated. In this study, we used the moisture recycling framework and a moisture tracking model to quantify the precipitation regulation services of TP ecosystems for their contribution to precipitation. We found TP ecosystems contributed substantially to local and downwind precipitation, with a contribution of 221 mm/year for the TP and neighboring areas through evapotranspiration (ET) (104 mm/year through transpiration), declined to <10 mm/year for eastern China and other surrounding countries. Among ecosystem types, grassland contributed most to precipitation, followed by barren and snow lands, forests, and shrublands. In terms of seasonality, precipitation contribution from TP ecosystems was greater in summer months than in non‐summer months for western China, while the opposite was true for eastern China—although the magnitude was much smaller. Over the past two decades, the significant ET increases in TP translated to a widespread increase in precipitation contribution for TP and downwind beneficiary regions from 2000 to 2020. Our study provides a quantitative way to understand the precipitation regulation services of TP ecosystems through moisture recycling, substantiating their key role to maintain precipitation and the water cycle for downwind regions—effectively acting as an ecological safeguard that could be perceived by the public. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogen (EKO) is characterized by widely distributed granitoids with different ages, which are keys to understanding the tectonic evolution of the Central China Orogenic Belt. Zircon U–Pb ages and Hf isotopic compositions, as well as the whole rock geochemistry of the gneissic granite from the basement rock, are carried out to elucidate the Meso– to Neoproterozoic tectonics of the EKO. The Al–rich minerals, including muscovite and tourmaline, and the A/CNK ratios (1.07–1.18) indicate S–type affinity of the granite. The granite displays high SiO 2 and K 2 O contents, and slightly enrichment in LREE in chondrite normalized REE distribution pattern with strong negative Eu anomalies (δEu = 0.10–0.15). The samples exhibit positive anomalies of Rb, Th, U and Pb, and depletion of Ba, Nb, Ta, Sr and Ti. Meanwhile, the high Rb/Ba and Rb/Sr ratios and low (CaO + FeO + MgO + TiO 2 ) contents indicate that they were derived from pelitic material. Together with the negative ε Hf ( t ) values ranging from −5.97 to −2.34 and two–stage Hf model ages varying from 1968 to 1786 Ma, the gneissic granite is suggested being originally derived from partial melting of the metasedimentary rocks of the Paleoproterozoic Jinshuikou Group in the central EKO due to the crust thickening. Most zircon grains from the gneissic granite show typical magmatic zircon morphology, and yield an U–Pb upper intercept age of 1006 ± 20 Ma (MSWD = 1.5), representing the crystallization age. Integrated with the regional geology, our results suggest that the EKO has been probably involved into a Meso– to Neoproterozoic plate collisional event related to the assembly of the Rodinia supercontinent. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogenic Belt (EKOB) in the northern margin of the Tibet Plateau is characterized by widespread granitic plutons, which are keys to understanding the tectonic evolution of the EKOB. The Zhiyu pluton, newly recognized in the central part of the EKOB, mainly consists of monzogranites, biotite granites and quartz diorites. Their LA-ICPMS zircon U-Pb results show formation ages of 447 ± 1.6 Ma, 448 ± 2.5 Ma and 408 ± 1.8 Ma. The monzogranites and biotite granites are characterized by relatively high Sr (208–631 ppm), low Y (4.28–15.82 ppm) and Yb (0.44–1.59 ppm) contents, thus resulting in elevated Sr/Y (30–105) and (La/Yb) N (4–79) ratios, indicating geochemical features of adakitic rocks. These adakitic granites are medium- to high-K, calcic or calc-alkaline in composition, and display a weak peraluminous character. They have low MgO (0.57–1.84 wt.%, average 1.01 wt.%), Mg# (40–53, average 45), as well as low Cr (3.67–17.98 ppm, average 7.19 ppm) and Ni (2.59–9.30 ppm, average 4.71 ppm) contents. These rocks are enriched in LREE, and show negligible or variable positive Eu anomalies (Eu/Eu ∗ = 0.61–3.80, average 1.45) and significant negative Nb and Ta anomalies. Majority of the zircon grains from these adakitic granitic rocks have positive ε Hf(t) values of 0.09–5.21 with two-stage model ages ranging from 1.1 Ga to 1.6 Ga. These features are compatible with those of adakitic rocks derived from a thickened lower crust in the garnet stability field. Their formation is mainly controlled by the process of crust thickening following the closure of the Qimantag Ocean. The younger quartz diorites belong to medium- to high-K, calc-alkalic or alkali-calcic and metaluminous series, and exhibit a relatively high MgO (2.23–5.18 wt.%) and Mg# (40–56, average 50.11), with significant LREE enrichment and negative Eu anomalies, as well as depletion of Nb, Ta. In addition, the quartz diorites have an enriched ε Hf(t) values ranging from −5.25 to −3.19. Combining the regional tectonic data, we infer that the younger quartz diorites were derived from enriched lithospheric mantle sources and contaminated by the crustal materials in a post-collision extensional setting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Shear-wave splitting in and around the NE Tibetan Plateau mainly reflects anisotropy in the lithospheric mantle. • Dominant NW-SE anisotropy in the lithospheric mantle indicates NE-SW compression. • Fossil anisotropies exist in the interior Alxa Block and the western Ordos Block. The northeastern Tibetan Plateau (NETP) is a key region to clarify the nature and mechanism of the Tibetan Plateau expansion. This region includes the eastern Qilian Orogenic Belt, the Alxa Block, the Helan-Yinchuan Tectonic Belt and the Ordos Block. We make shear-wave splitting measurements using teleseismic waveforms recorded at 17 portable broadband stations that we newly deployed in the study region. Our measurements provide new information on seismic anisotropy and deformation patterns in the lithospheric mantle, which can be used to constrain the extent of the NETP northeastward expansion. The dominant fast polarization direction (FPD) is NW-SE in the eastern Qilian Orogenic Belt, the southern Alxa Block and the Helan-Yinchuan Tectonic Belt, subparallel to the prominent orientation of tectonics in the NETP. The same NW-SE FPD in the three tectonic units indicates NE-SW compression in the lithospheric mantle there caused by the NETP northeastward expansion. NE-SW FPDs are revealed in the interior Alxa Block, which may reflect fossil anisotropy probably formed by the Paleo-Asian oceanic subduction and closure. ENE-WSW FPDs exist in the western Ordos Block, reflecting fossil anisotropy probably caused by convergence of the South China Craton and North China Craton. Combined with the NW-SE FPDs in the southwestern margin of the Ordos Block revealed by previous studies, our results suggest that the NETP northeastward expansion has obviously affected the southern Alxa Block and the southwestern margin of the Ordos Block. However, its recent northeastward expansion mainly occurred along the Helan-Yinchuan Tectonic Belt. [ABSTRACT FROM AUTHOR]