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Under the climate warming, the ice avalanches (IAs) and glacier lake outburst floods (GLOFs) will continue or even intensify in the future. In order to find out the number, spatial distribution, and characteristics of hidden dangers of IA and GLOF-prone lakes on the Tibetan Plateau (TP), the first inventory is presented. (1) The study has identified and analyzed 581 IAs and 369 GLOFs on the TP. IAs and GLOFs are widely distributed in the Tibet Autonomous Region (TAR), concentrating in the Yarlung Zangbo River basin and the Nyainqntanglha and Himalaya Mountain range. (2) Most of the IAs have an area of 0.1 ~ 1 km2. The IAs occur on vulnerable slopes ranging from 35 to 45°, with an elevation between 4500 and 5500 m and a north-friendly aspect. (3) Most of the GLOFs with a lake area of 0.1 ~ 0.3 km2 and a north-facing outburst direction are developed in an elevation range from 4500 to 5500 m. There are about half of the GLOF-prone lakes to be close to the front edge of the mother glaciers. (4) The front elevation of IAs changes regularly with the eastern Himalayan syntaxis region as the boundary. It generally increased from west to east on the west side, while a "V-shaped" trend first decreased and then increased, and decreased from south to north on the east side. (5) The IAs and GLOFs are mainly distributed in the southern and northwestern TP with "clustering" characters due to the topographical and climatic settings. [ABSTRACT FROM AUTHOR]

Ancient dammed lake deposits, developed in tectonically active mountainous areas, record high-resolution changes in paleoclimate and paleoseismicity. This paper reports a massive ancient dammed lake, the "Aniangzhai paleolandslide-dammed lake", newly discovered in the upper reaches of the Dadu River on the eastern margin of the Tibetan Plateau. Optically stimulated luminescence (OSL) dating showed that this lake formed prior to 15.7 ± 1.9 ka and persisted for 7 ka. The basic properties of lacustrine sediments and abnormal fluvial deposits of the dammed lake were identified through field sedimentological investigation and use of unmanned aerial vehicle (UAV) technology. Through a literature review of reservoir siltation, several methods of estimating the dam surface elevation were summarized, and on this basis, the Aniangzhai paleolandslide and ancient dammed lake were reconstructed. The results indicated that the Aniangzhai ancient dammed lake extended for 79 km upstream, with a maximum sediment thickness of 128 m. The lake at one time held back an area and volume of water of 53.5 km2 and 5.74 × 109 m3, respectively. This study proposed the fluvial-dammed lake sedimentary zoning system of ancient dammed lakes based on changes in sedimentary characteristics among different sections: (1) deep–semi-deep lake; (2) shallow lake; (3) lakeshore; and (4) area of river–lake intersection. This study also discussed a general, but systematic and novel model under which ancient dammed lakes in mountainous areas evolve. It may provide new information on the evolution of the paleoclimatic environment in the eastern Tibetan Plateau after the Last Glacial Maximum. • A huge ancient dammed lake in the eastern Tibetan Plateau has been newly discovered. • The Aniangzhai paleolandslide and ancient dammed lake were reconstructed. • The fluvial-dammed lake sedimentary zoning system of dammed lakes was proposed. • A general evolution model of ancient dammed lakes was proposed. • Several methods of estimating the surface elevation of landslide dams were discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The deformation of the Huayingshan belt is featured by NW compression and NE transpression. • The two stages of deformation occurred at ∼105–78 Ma and ∼38–19 Ma, respectively. • Tectonic regime of the Huayingshan was dominated by the Xuefengshan belt in the Cretaceous and Tibetan Plateau in the Neogene. The Huayingshan tectonic belt in South China marks the tectonic boundary between the Xuefengshan intracontinental orogenic belt and the Sichuan Basin, and thus records interactions between the two domains. However, the processes of these interactions are still unclear due to the lack of knowledge about deformation patterns and timings. In this study, we present geometry and kinematics of the central Huayingshan tectonic belt in the Laogongqiao area (a critical location in the eastern Sichuan Basin) using field mapping, paleostress analysis and calcite U-Pb dating. Structural analysis indicates this belt is mainly featured by a southwest-plunging anticlinorium and syntectonic northwest-verging imbricated thrust faults (D1) that are cut by a left-lateral transpressional fault (D2). Results of paleostress analysis and calcite U-Pb dating from fault zones further demonstrate two stages of deformation of the Huayingshan tectonic belt, in the Late Cretaceous (105–78 Ma) and Late Eocene-Early Miocene (38–19 Ma), respectively. The deformation scenarios are correspondingly interpreted to be associated with a) final termination of the northwestward propagation of the Xuefengshan intracontinental orogenic belt during the Cretaceous; and b) eastward extrusion, uplift and southeastward escape of the Tibetan Plateau during the Neogene. Thus, the Sichuan Basin, which lies between these two active areas, underwent compression and counterclockwise rotation during the Late Eocene-Early Miocene time. As a result of the conjugation, movement along the right-lateral Leibo fault led to partial division of the southern Huayingshan tectonic belt into a system of large folds, that in map view forms a splay diverging to southwest, by 19 Ma. [ABSTRACT FROM AUTHOR]

The surface uplift history of the Tibetan Plateau has provided a key boundary criterion for various geological, climatic, and environmental events since the Cenozoic. The paleoelevation history of the plateau is organically associated with interactions amongst deep geodynamics, earth surface processes, and climate change. Understanding of plateau uplift history has been advanced by the development of a number of paleoaltimetries and their application to studies of the Tibetan Plateau: the paleogeomorphic scenario for the Early Eocene Tibetan Plateau is thought to include two high mountains, the ca. 4500 m Gangdese Mountains to the south, and the ca. 5000 m Qiangtang Center Watershed Mountains to the north. Between these ranges, a low-elevation basin (ca. 2500 m) is thought to have been present. The Himalayas in the southern Tibetan Plateau was close to sea level at this time, while the Hoh Xil Basin in the north reached an elevation of no more than 1500 m. Thus, the so-called 'Roof of the World' Tibetan Plateau formed subsequent to the Miocene. Nevertheless,, the uplift histories of the different terranes that comprise this plateau currently remain unclear, which constrains the uplift history reconstruction of the entire Tibetan Plateau. Additional paleoelevation data from different areas, obtained using multi-paleoaltimeters, is required to resolve the forms and processes of Tibetan Plateau uplift and extension. [ABSTRACT FROM AUTHOR]

Abstract: Paleoelevation reconstruction using oxygen isotopes is making a significant contribution to understanding the Cenozoic uplift of the Himalayas and the Tibetan Plateau. This paper presents new oxygen and carbon isotopic compositions from well dated Tertiary paleosols, lacustrine calcareous carbonates, and marls from the Nianbo (60–54 Ma) and upper Pana Formations (51–48 Ma) of the Linzizong Group in the Linzhou (Penbo) Basin. The sediments of the Nianbo Formation, which are >180 m-thick, were deposited in alluvial fans, braided rivers, fan deltas, and on nearshore to offshore lacustrine settings, whereas those of the upper Pana Formation are >100 m-thick and are comprised predominantly of proximal alluvial fan and braided river deposits. Correlations between the lithofacies and stable isotopic compositions suggest that the basin was mainly a hydrologically open environment. It is confirmed that the and values from Nianbo and Pana Formations have not yet been reset by late-stage diagenesis based on petrographic examination, oxygen isotope of the fossil ostracodes, and tectonic deformation of strata. The paleoelevations are reconstructed using the corrected most negative paleosurface water values. These imply that the Linzhou area had attained an elevation of m during the period of the Indo-Asian collision, i.e., achieved a near-present elevation, and may form an Andean-type mountain range stretching the Gangdese arc before collision. The Gangdese Mountains probably maintained high elevations since at least the Paleocene and could play a crucial role in the climate change in the interior of the Tibetan Plateau during the Early Cenozoic. The paleogeomorphic scenario of the Eocene Tibet is proposed to exist at two high mountains in excess of 4500 m that sandwiched a low elevation basin. [Copyright &y& Elsevier]

Abstract: We investigate the crustal thickness, Poisson’s ratio, and the thickness variation of the mantle transition zone using the P receiver function technique on data recorded by the 68 seismic station of the ASCENT experiment beneath the northeast Tibetan plateau. Our results reveal a distinct crustal and upper mantle structure contrast between the western and eastern part of the northeast Tibetan plateau along two migrated profiles. In the eastern region the Moho is relatively smooth and continuous and varies in depth between ∼80 and 51km, whereas the depth of the Moho beneath the western region varies between ∼77 and 52km and is offset ∼20km beneath the boundary between the Kunlun fault and Qaidam basin. The delay times for the Ps phases from both the 410-km and 660-km discontinuities in the western region are ∼1.2s later than that in the eastern region, indicating that the average velocities of the upper mantle in the western region are lower than that in the eastern region. Crustal rocks with low- to moderate Poisson’s ratios are interpreted to be dominated by felsic to intermediate compositions, implying that large scale middle-lower crustal flow does not occur easily. The nearly constant thickness of the mantle transition zone, with an average value of ∼255km (24.4s) from south to north, implies that no lithospheric fragments correlating to the India–Asia collision have entered into the mantle transition zone. [Copyright &y& Elsevier]

Abstract: The timing of uplift of the Tibetan Plateau remains controversial, with estimates varying from Eocene to more recent than Pliocene. In particular, the paleoaltimetry of the Qiangtang terrane, on the central Tibetan Plateau, is completely unknown. Here, we present new stable isotope results of fluvial/lacustrine carbonate cement, pedogenic carbonate and marl from the Kangtuo and Suonahu formations deposited between ∼51 and ∼28Ma in the Heihuling–Bamaoqiongzong area of the northern Qiangtang terrane. The lithofacies associations indicate that the Kangtuo formation was deposited in alluvial fan and fluvial floodplain environments, and the Suonahu formation was deposited in near shore lacustrine, playa-lake and channelized fluvial environments. Carbon and oxygen isotope values, coupled with the sedimentary facies interpretations, point to evaporation and low respiration rates in the Eocene–Oligocene paleosols, suggesting an arid climate in the high Qiangtang area at the time. The δ 18Opsw values of paleo-surface water reconstructed from the lowest (i.e. the least evaporated) δ 18Oc (PDB) values of the unaltered authigenic carbonates are used to make the minimum estimates of the average paleoelevation of the drainage basin. The paleoelevation of the northern Qiangtang terrane is reconstructed as above 5000m by at least the middle Oligocene (28Ma), similar to the present elevation in this area. The aridity and the positive shift in oxygen isotope values of surface waters in our study area may suggest that the high Lhasa terrane established by the middle Oligocene blocked the northward transport of tropical moisture. Maintenance of high elevation (>5000m) from at least the Oligocene to the present suggests that the Qiangtang crust was already thickened by that time, and that underthrusting of India beneath Asia since then has continued to provide additional material while at the same time driving Asian lower crust eastward by crustal flow. [Copyright &y& Elsevier]

Fossil tooth enamel from herbivores is considered one of the best proxies for paleoclimate and paleoelevation reconstructions, due to its low susceptibility to diagenetic alteration. A synthesis of oxygen and carbon isotope analyses of modern tooth enamel from herbivores such as Tibetan yaks, asses and antelopes is assessed. The average δ13C(PDB) value of herbivore tooth enamel in the Lhasa and south Qiangtang terrains is -11.3‰ ± 1.1‰, whereas in the north Qiangtang and Hoh Xil terrains value is -10.2‰ ± 1.4‰ consistent with the current C3-dominant ecotype in the Tibetan Plateau. In addition, the average δ 18O(PDB) values from tooth enamel show a northward systematic increase from -11.8‰ ± 3.4‰ in the Gyirong Basin, to -11.1‰ ± 1.1‰ in the Lhasa and southern Qiangtang terrains, and then to -9.0‰ ± 1.1‰ in the northern Qiangtang and the Hoh Xil areas, similar to those of the local river water and precipitation variation trends. It is suggested that δ18O(PDB) values of tooth enamel should not be used directly to evaluate the paleo-elevation of the Tibetan Plateau, because oxygen isotopic composition from tooth enamel is a combination of drinking water (precipitation- and river-sourced) and diet (plant-sourced). Moreover, an empirical relationship between oxygen isotope of tooth enamel and modern river water, and as well as elevation is recommended, which can be used in future studies of Tibetan Plateau paleoelevation. [ABSTRACT FROM AUTHOR]

The Newmark displacement (ND) method, which reproduces the interactions between waves, solids, and fluids during an earthquake, has experienced numerous modifications. We compare the performances of a traditional and a modified version of the ND method through the analysis of co-seismic landslides triggered by the 2022 Ms 6.8 Luding earthquake (Sichuan, China). We implemented 23 ND scenarios with each equation, assuming different landslide depths, as well as various soil-rock geomechanical properties derived from previous studies in regions of similar lithology. These scenarios allowed verifying the presence or absence of such landslides and predict the likely occurrence locations. We evaluated the topographic and slope aspect amplification effects on both equations. The oldest equation has a better landslide predictive ability, as it considers both slope stability and earthquake intensity. Contrarily, the newer version of the ND method has a greater emphasis on slope stability compared to the earthquake intensity and hence tends to give high ND values only when the critical acceleration is weak. The topographic amplification does not improve the predictive capacity of these equations, most likely because few or no massive landslides were triggered from mountain peaks. This approach allows structural, focal mechanism, and site effects to be considered when designing ND models, which could help to explain and predict new landslide distribution patterns such as the abundance of landslides on the NE, E, S, and SE-facing slopes observed in the Luding case. [ABSTRACT FROM AUTHOR]

Earthquake-induced landslides, also called seismic landslides (SLs), are some of the most catastrophic natural hazards on the Tibetan Plateau (TP). They have frequently caused disastrous impacts on human society but are also important driving forces in regional evolution. The rapid development of multiple advanced techniques and more relevant studies have contributed to much progress in understanding SLs, but a synoptic survey that combines the insights of related studies to build a comprehensive understanding of SLs on the Tibetan Plateau is currently lacking. Here, we adopt recent SLs triggered by the 2005 Kashmir (Mw 7.6), 2008 Wenchuan (Mw 7.9), 2010 Yushu (Mw 6.9), 2013 Lushan (Mw 6.6), 2013 Minxian (Mw 5.5), 2015 Gorkha (Mw 7.8), 2017 Jiuzhaigou (Mw 6.5), 2017 Nyingchi (Mw 6.5), 2022 Lushan (Mw 5.8) and 2022 Luding (Mw 6.6) earthquakes on the TP to overview some advances in data preparation, spatial patterns and controls, landslide patterns and causes, movement and landslide damming, susceptibility, and long-term evolution. The study first summarizes worldwide seismic events that have triggered SLs since 2000 to confirm the TP is a SL-prone area and points out detailed SL-prone tectonic blocks on the TP. Based on landslide inventories of 10 adopted events, the study investigates the SL spatial distribution and finds tectonic and geomorphic controls of SL distribution. The landslide inventories also help us confirm the relationships of landslide sizes (SL number, SL area and SL volume) and magnitudes. Next, we summarize the landslide patterns and possible failure causes and highlight that seismic amplification could play an important role for SL occurrence on steep mountains. We use two important indicators, namely, landslide mobility (H/L) and landslide velocity, to reveal SL movement characteristics; we analyze the characteristics of SL damming, dam breaks and outburst floods; we analyze the SL susceptibility process and propose the most common landslide controlling factors (altitude, slope, PGA, seismogenic faults, rivers and stratigraphy) for SL susceptibility; we analyze postseismic evolution using two important indicators, namely, landslide activity and debris flow activity. Finally, we compare the results with other earthquakes worldwide and find that the TP is more sensitive to SLs; SL distribution laws of other worldwide seismic events are not fully consistent with those of the TP, including few seismic liquefaction landslides occur on the TP, while it is common for coastal earthquakes, and SLs on the TP require longer recovery periods. [ABSTRACT FROM AUTHOR]

We present herein detailed images of the Moho depth and V p/ V s ratio along ANTILOPE-1 profile beneath the western Tibetan Plateau derived from receiver function analysis. Along the ANTILOPE-1 profile, a rapidly northward-dipping Moho extends from ∼50 km below the Himalaya to ∼80 km across the Indus–Yarlung suture, shallowing to ∼66 km under the central Lhasa terrane. The Moho depth shows a dramatic increase from ∼66 km north of the Bangong–Nujiang suture to ∼93 km beneath central Qiangtang terrane where it reaches the maximum depth observed along this profile before steeply rising to ∼73 km. We interpret both the 15 and 20 km offsets of Moho depth occurring beneath the central Lhasa and central Qiangtang terranes as being related to the northern frontiers of the decoupled underthrusting Indian lower crust and lithospheric mantle, respectively. The Moho remains at a depth of ∼70 km with a slight undulation beneath the northern Qiangtang and Songpan–Ganzi terranes, and then abruptly shallows to ∼45 km near the Altyn Tagh Fault. The ∼25 km Moho offset observed at the conjunction of the Tarim Basin and the Altyn Tagh mountain range suggests that the crustal shortening is achieved by pure shear thickening without much underthrusting. The average crustal V p/ V s ratio changes from 1.66 to 1.80 beneath the Himalaya, the Lhasa terrane and the Tarim Basin indicating a felsic-to-intermediate composition. However, higher V p/ V s ratios between 1.76 and 1.83 (except for a few outlying low values) are found beneath the Qiangtang and Songpan–Ganzi terranes, which could be attributed to the joint effects of the more mafic composition and partial melt within the crust. The Moho depth and V p /V s ratio exhibit complex N–S variations along this profile, which can be attributed to the joint effects of Indian lower crust underthrusting, the low-velocity zone of the mid-upper crust, crustal shortening and thickening, and other involved dynamic mechanisms. [ABSTRACT FROM AUTHOR]

As the Third Pole of the Earth and the Water Tower of Asia, the Tibetan Plateau (TP) nurtures large numbers of glacial lakes, which are sensitive to global climate change. These lakes modulate the freshwater ecosystem in the region but concurrently pose severe threats to the valley population by means of sudden glacial lake outbursts and consequent floods (GLOFs). The lack of high-resolution multi-temporal inventory of glacial lakes in TP hampers a better understanding and prediction of the future trend and risk of glacial lakes. Here, we created a multi-temporal inventory of glacial lakes in TP using a 30-year record of 42,833 satellite images (1990–2019), and we discussed their characteristics and spatio-temporal evolution over the years. Results showed that their number and area had increased by 3285 and 258.82 km2 in the last 3 decades, respectively. We noticed that different regions of the TP exhibited varying change rates in glacial lake size; most regions show a trend of expansion and increase in glacial lakes, while some regions show a trend of decreasing such as the western Pamir and the eastern Hindu Kush. The mapping uncertainty is about 17.5%, which is lower than other available datasets, thus making our inventory reliable for the spatio-temporal evolution analysis of glacial lakes in the TP. Our lake inventory data are publicly published, it can help to study climate change–glacier–glacial lake–GLOF interactions in the Third Pole and serve as input to various hydro-climatic studies. [ABSTRACT FROM AUTHOR]

The long‐term evolution of the Tibetan Plateau significantly influenced Asian climate, nearby ocean physics and chemistry, and terrestrial biodiversity. This range of impacts has attracted research attention from a correspondingly broad range of disciplines, providing important new insights into prolonged and emerging debates concerning the Himalayan–Tibetan morphotectonic evolution and its impacts on the long‐term evolution of climate, biodiversity, and the environment on regional to global scales. To communicate the latest advances on this coupled tectonic, climatic and biological system, we have launched a special virtual issue in Terra Nova and solicited submissions of 20 papers in total. The papers cover a wide range of topics that fall in the following, partially overlapping, categories: pre‐India–Asia collision tectonic configuration; post‐collision deformation; sedimentary system: source to sink studies, climatic forcing, and river incision; and climatic and biospheric influence of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Many lakes on the Tibetan Plateau are surrounded by palaeo-shorelines that document former lake-level highstands and hence past changes in climate. Establishing accurate chronologies for these shorelines is crucial to correlate lake-level fluctuations with palaeo-environmental histories that are commonly inferred from lake sedimentary records. Here we apply surface exposure dating to constrain the age of two lake-level highstands at one of the largest Tibetan lakes – Tangra Yumco – which has well developed palaeo-shorelines located up to ∼185 m above the current lake. For sampling we focussed on wave-cut bedrock terraces that vary considerably in width, because they were carved into rocks of different erodibility. Samples from the highest strath terrace (∼180–185 m above the lake) at three different sites yield tightly clustered 10Be ages between 7.39 ± 0.19 ka and 7.87 ± 0.27 ka (internal errors), which constrain the end of an early Holocene lake-level highstand at 7.6 ± 0.6 ka (external error). The consistency of the 10Be ages indicates that bedrock erosion by wave attack reduced the inherited 10Be component to negligible amounts, because otherwise samples would show considerable age scatter. Two bedrock samples from a lower terrace (∼140–145 m above the lake) and one amalgamated clast sample from a beach ridge on the same terrace yield 10Be ages between 4.04 ± 0.14 ka and 4.50 ± 0.15 ka. These ages document that the lake level dropped by ∼40 m between ∼7.6 ka and ∼4.3 ka. Granite boulders from the two investigated terraces yield apparent 10Be ages that are ∼6 ka and ∼27 ka older than the ages of the respective terraces, indicating that this sample type is not reliable in this setting. Overall, our results demonstrate that exposure dating of bedrock terraces provides a valuable tool to reconstruct lake-level histories on the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Abstract Active thrust faulting at the front of the Qilian Shan accommodates the northeastward growth of the Tibetan Plateau, however, the lifespan of individual faults and their slip history on different timescales remain largely unknown. Here, we show that the main range-bounding thrust fault of the western Qilian Shan has accrued tectonic slip at an almost constant rate during the last ∼200 ka, and possibly since fault initiation in the mid-Miocene. Our finding is based on 10Be ages from a flight of five deformed fluvial terraces along the Hongshuiba river, which constrain the vertical slip rate of the Qilian Shan frontal thrust to be 1.2 ± 0.1 m/ka during the last 200 ka. With a fault dip of 30 ± 5 ° constrained by seismic reflection data, we obtain a horizontal shortening rate of 2.0 ± 0.3 m/ka. This value is consistent with both the short-term shortening rate of 1.7 ± 0.3 mm/a derived from GPS data and the long-term shortening rate of 2.1 ± 0.4 m/ka, which is based on a balanced geological cross-section. The latter provides a total shortening estimate of 25 ± 3 km since the thrust fault initiated 12 ± 2 Ma ago. The agreement between the shortening rates on the range of timescales between 100 and 107 years suggests that the western Qilian Shan frontal thrust has slipped at a steady rate since its initiation and implies that this fault is the main structure responsible for the growth of the western Qilian Shan. Highlights • 10Be ages for five river terraces constrain slip rate of Qilian Shan frontal thrust. • 10Be-based shortening rate is consistent with a balanced cross-section and GPS data. • Shortening on Qilian Shan frontal thrust proceeded at steady rate since mid-Miocene. • New sampling strategy for exposure dating of loess-covered fluvial terraces. [ABSTRACT FROM AUTHOR]

The catastrophic Sanyanyu and Luojiayu debris flows, which were induced by heavy rainfall, occurred at approximately midnight, August 7th, 2010 (Beijing time, UTC + 8) and claimed 1,765 lives. Most seismic stations located within 150 km did not detect the debris flows except for the closest seismic station, ZHQ, indicating that the seismic signals generated by the debris flows decayed rapidly. We analyzed broadband seismic signals from the ZHQ seismic station, beginning approximately 20 min before the outbreak of the Sanyanyu debris flow, to rebuild its evolution processes. Seismic signals can detect development of the Sanyanyu debris flow approximately 20 min after a heavy rain started falling in its initiation area; this time was characterized by a gradual increase in seismic amplitude accompanied by a series of spike signals that were probably generated by rock collapses within the catchment. The frequency contents and the characteristics of seismic signals before and after 23:33:15 (T 1 ) are distinctively different, which we interpret as being generated by a large quantity of flowing material entering the main channel, marking the formation of the Sanyanyu debris flow. We attribute seismic amplitude increases between 23:33:15 (T 1 ) and 23:34:26 (T 2 ) and between 23:35:40 (T 3 ) and 23:36:49 (T 4 ) to entrainment of the deposit material after initiation of the debris flow and to its flow through a colluvial deposit area, respectively. The main frequency band broadening of seismic signals after 23:37:30 (T 5 ) is believed to have been induced by impacts between the flowing material and check dams. [ABSTRACT FROM AUTHOR]

The topography evolution of the southeastern Tibetan Plateau provides a constraint for evaluating various geodynamic models of plateau formation. We reconstruct the Paleocene to Eocene paleoelevation of the Cenozoic Gonjo basin in the Qiangtang terrane, using oxygen and carbon stable isotopic results from pedogenic carbonates of the lower Ranmugou Formation. Lithofacies associations indicate that the lower Ranmugou Formation was deposited in alluvial fan and fluvial floodplain environments. U-Pb dating of volcanics within the middle Ranmugou Formation constrains the deposition of the lower Ranmugou Formation as prior to 43.2 Ma. Paleoelevations are calculated using both a thermodynamic model and an empirical relationship. The empirical relationship of elevation-δ 18 O is determined from a series of modern water samples. Calculated paleoelevations indicate that the Gonjo basin attained a minimum average elevation of 2100–2500 m in the early Eocene. Together with recent paleoaltimetry studies in the region, it can be concluded that the crust of southeastern Tibetan Plateau was already thickened by that time. The calculation is based on the section in northern Gonjo basin, where δ 18 O values of paleosol nodules appear to be unaltered, but we cannot rule out the possibility that δ 18 O values of the pedogenic carbonates had been partially reset. Our preliminary results favor tectonic models compatible with pre-Miocene uplift of the SE-central Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Recently, we have processed the gravitational and geomagnetic data from a geophysical survey along a profile (Baicheng to Da Qaidam) which crosses the northern and eastern Tarim Basin, the Altyn Tagh Mountains, and the Qaidam Basin, respectively. Based on the P- and S-wave velocities (Zhao et al., 2006), both the density and magnetic intensity of the crust and uppermost mantle were determined by using a joint inversion of gravity versus geomagnetism. Our new results at the northern margin of the Tibetan Plateau reflect different crustal structures beneath Tarim basin and Qaidam basin, and these two basins may be produced by different terranes. In addition, strong deformation has occurred in the basement and interior of the Qaidam Basin during the tectonic evolution. [ABSTRACT FROM AUTHOR]

• The levels of 43 carotenoids were determined in peaches accessions. • Carotenoids varied significantly and were at higher concentrations in Tibetan peach. • PSY, CCD4 and BCH were differently expressed at different altitudes in Tibetan peach. Carotenoids are important secondary metabolites that may participate in response to extreme environments. Fruit color changes were observed in peaches growing at altitude on the Tibetan Plateau. Here, we qualitatively and quantitatively analyzed 43 kinds of carotenoids in 96 Tibetan peach and 12 cultivated peach fruit samples. Comparative analysis revealed that 25 kinds of carotenoids accumulated at significantly different levels between Tibetan peaches and cultivated peaches. Based on a population structure analysis, the carotenoid levels of Tibetan peaches were divided into two groups, which are mainly affected by the environmental factors light and temperature. The correlation analysis implied that the levels of 9 carotenoids were significantly correlated with altitude. qRT–PCR results showed that PSY , CCD4 and BCH were significantly differently expressed between the low and high altitude Tibetan peaches. In summary, this study showed that the abundant variation in carotenoids was highly associated with high-altitude adaptations in Tibetan peach fruit. [ABSTRACT FROM AUTHOR]

Many lakes on the Tibetan Plateau exhibit strandplains with a series of beach ridges extending high above the current lake levels. These beach ridges mark former lake highstands and therefore dating their formation allows the reconstruction of lake-level histories and environmental changes. In this study, we establish a lake-level chronology of Tangra Yum Co (fifth largest lake on the Tibetan Plateau) based on luminescence dating of feldspar from 17 beach-ridge samples. The samples were collected from two strandplains southeast and north of the lake and range in elevation from the current shore to 140 m above the present lake. Using a modified post-infrared IRSL protocol at 170°C we successfully minimised the anomalous fading in the feldspar IRSL signal, and obtained reliable dating results. The luminescence ages indicate three different stages of lake-level decline during the Holocene: (1) a phase of rapid decline (~ 50 m) from ~ 6.4 to ~ 4.5 ka, (2) a period of slow decline between ~ 4.5 and ~ 2.0 ka (~ 20 m), and (3) a fast decline by 70 m between ~ 2 ka and today. Our findings suggest a link between a decrease in monsoonal activity and lake-level decline since the early Holocene. [ABSTRACT FROM AUTHOR]

Abstract: We present the results of a seismic wide-angle reflection/refraction profile across the central Qaidam basin, the largest basin within the Qinghai-Tibetan plateau. The 350-km‐long profile extends from the northern margin of the East-Kunlun Shan to the southern margin of the Qilian Shan. The P- and S-wave velocity structure and Poisson''s ratio data provide constraints on composition. The crust here consists of a near-surface sedimentary layer and a four-layered crystalline crust having several significant features. (1) The sedimentary fill of the Qaidam basin reaches a maximum thickness of 8km, and the basin shape mirrors the uplifted Moho. (2) Within the four layers of the crystalline crust, P- (S-) wave velocities increase with depth and fall within the following velocity ranges: 5.9–6.3km/s (3.45–3.65km/s), 6.45–6.55km/s (3.7km/s), 6.65km/s (3.8km/s), and 6.7–6.9km/s (3.8–3.9km/s), respectively; (3) low-velocity zones with a 3–5% reduction in seismic velocity are detected in the lower half of the crust beneath the Qaidam basin and its transition to the Qilian Shan. (4) The crystalline crust is thickest beneath the northern margin of the basin towards the Qilian Shan (58–62km) and thinnest beneath the center of the basin (52km). Variations in crustal thickness are caused most pronouncedly by thickness variations in the lowermost layer of the crust. (5) Poisson''s ratio and P-wave velocity values suggest that the Qaidam crust has an essentially felsic composition with an intermediate layer at its base. Based on the crustal structure reported here, we suggest that late Cenozoic convergence is accommodated by thick-skinned tectonic deformation with thickening involving the entire crust across the Kunlun–Qaidam–Qilian system. [Copyright &y& Elsevier]

Leucogranites play a significant role in understanding crustal thickening, melting within continental collisional belts, and plateau uplift. Field investigations show that Miocene igneous rocks from the Hoh Xil Lake area mainly consist of two-mica leucogranites and rhyolites. We studied the Bukadaban two-mica leucogranites and the Kekao Lake, Malanshan and Hudongliang rhyolites by zircon U-Pb, muscovite and sanidine Ar/Ar geochronology, and whole-rock geochemical and Sr-Nd isotopic analysis. Results yielded crystallization and cooling ages for the Bukadaban leucogranites of 9.7±0.2 and 6.88±0.19 Ma, respectively. Extrusive ages of the Kekao Lake and Malanshan rhyolites are 14.5±0.8 and 9.37±0.30 Ma, respectively. All rocks are enriched in SiO (70.99%-73.59%), AlO (14.39%-15.25%) and KO (3.78%-5.50%) but depleted in FeO (0.58%-1.56%), MgO (0.11%-0.44%) and CaO (0.59%-1.19%). The rocks are strongly peraluminous (A/CNK=1.11−1.21) S-type granites characterized by negative Eu anomalies ( δEu=0.18−0.39). In also considering their Sr-Nd isotopic compositions (Sr/Sr=0.7124 to 0.7143; ε Nd (9 Ma) =−5.5 to −7.1), we propose that these igneous rocks were generated through dehydration melting of muscovite in the thickened middle or lower crust of northern Tibet. Melting was probably triggered by localized E-W stretching decompression in the horse tails of Kunlun sinistral strike-slip faults. Reactivation of the Kunlun strike-slip faults, accompanied by emplacement of leucogranite and eruption of rhyolite in the Hoh Xil Lake area, indicates that large-scale crustal shortening and thickening in northern Tibet mainly occurred before 15 Ma. In addition, these findings suggest that the northern Tibetan Plateau attained its present elevation (∼5000 m) at least 15 Ma ago. [ABSTRACT FROM AUTHOR]