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10Be/7Be is a stratospheric sensitive tracer. In this paper, measurements of 10Be/7Be and surface O3 from October 2005 to May 2006 at Mt. Waliguan (hereafter WLG, 100.898°E, 39.287°N, 3810 m, a.s.l.), China global atmospheric watch (GAW) observatory, are introduced and used to investigate the stratosphere-troposphere transport (STT) and its impact on surface O3 on the Tibetan Plateau. The results show that the magnitude of STT is weak in winter, followed by strengthening from the end of winter to 10 7 10 7 the middle of spring (from mid February to mid April) with large increases in Be, Be, Be/ Be and surface O3. At the end of spring (from the end of April to mid May in this paper), the STT weakened, and the continuous increase of surface O3 at WLG is produced by tropospheric photochemistry reactions. [ABSTRACT FROM AUTHOR]

This paper describes 2007/2008 inter-annual changes in runoff from the Zhadang Glacier located on the northern slope of Nyainqêntanglha Range, Tibet, and analyzes their causes. Precipitation increased by 17.9% in summer months of 2008 compared with the same period in 2007, drainage basin runoff decreased by 33.3%, and glacial meltwater decreased by 53.8%. Change in positive accumulated air temperature explained approximately half of the inter-annual difference in glacial meltwater using a degree-day model. This suggests that the glacier is extremely sensitive to changes in air temperature. Energy balance analysis showed that change in glacier surface albedo, considered to be caused by difference in precipitation form, resulted in the large inter-annual difference in glacial meltwater. It was shown statistically that precipitation form in the summer months of 2007 was mainly rainfall which comprised 71.5% of total precipitation, while during the same period in 2008 rainfall accounted for 30.7%, with the majority of precipitation falling as snow. Precipitation form should be considered an independent factor when analyzing glacier sensitivity to climate change or forecasting the runoff from certain glaciers. [ABSTRACT FROM AUTHOR]

Early-crystallizing chromian spinel (Cr-spinel) in the Nagqu ophiolite has high Os and low Re contents, and it is resistant to alteration during serpentinization, weathering and metamorphism. The chemical composition of primitive magma is preserved in Cr-spinel, which makes it suitable for determining the initial Os-isotope composition of the mantle source. This study presents Cr-spinel Os isotopes and zircon U-Pb ages for cumulate dunite and gabbro, respectively, in the same cumulate section of the ophiolite at Nagqu in Tibet. The results shed light on the formation and evolution of lithospheric mantle. The Nagqu ophiolite is located in the central part of the Bangong-Nujiang suture zone. It is a remnant of the Neotethyan oceanic crust, and contains cumulate dunite and gabbro. Zircon from the gabbro yielded a weighted mean Pb/U age of 183.7±1 Ma. Cr-spinel exhibits γ values of −0.2 to −0.3, suggesting that the mantle source for the dunite is similar to that of carbonaceous chondrites. Thus, the Tibetan lithosphere is primarily a relic of Tethyan oceanic lithosphere, which has formed by the transformation of the normal asthenospheric mantle in the Mesozoic. This is the first study to combine the spinel Os isotopes with accurate zircon U-Pb ages to constrain the geochemical characteristics of the mantle source for the ophiolite. [ABSTRACT FROM AUTHOR]

Four wetland maps for all China have been produced, based on Landsat and CBERS-02B remote sensing data between 1978 and 2008 (1978, 1990, 2000 and 2008). These maps were mainly developed by manual interpretation and validated by substantial field investigation in 2009. Based on these maps, we analyzed the 2008 wetland distribution in China and discussed wetland changes and their drivers over the past 30 years. (i) There were about 324097 km of wetlands in 2008, for which inland marshes or swamps were the most common wetland type (35%), with lakes (26%) second. Most of the wetlands were in Heilongjiang, Inner Mongolia, Qinghai and Tibet, occupying about 55% of the national wetland area. (ii) From 1978 to 2008, China's wetland area continually and significantly decreased, by about 33% based on changes in the wetland map. This was in sharp contrast to the increase in artificial wetlands, which increased by about 122%. Inland marshes accounted for the main loss of total wetlands from 1978 to 2000. From 2000 through 2008, riverine and lacustrine wetlands constituted the main wetland loss. Fortunately however, the rate of wetland loss decreased from 5523 to 831 km/a. (iii) The change ratio of lost natural wetlands (including inland and coastal wetlands) to non-wetlands has decreased slightly over the past 30 years. From 1978 to 1990, nearly all natural wetlands (98%) lost were transformed into non-wetlands. However, the ratio declined to 86% from 1990 to 2000, and to 77% from 2000 to 2008. (iv) All Chinese provinces were divided into three groups according to patterns of wetland changes, which could relate to the driving forces of such changes. Tibet was completely different from other provinces, as it was one representative example in which there was a net wetland increase, because of global warming and decreased human activity since 1990. Increased economic development caused considerable wetland loss in most eastern provinces, and artificial wetlands increased. [ABSTRACT FROM AUTHOR]

Determination of the timing and geochemical nature of early metamorphic and anatectic events in the Himalayan orogen may provide key insights into the physical and chemical behavior of lower crustal materials during the early stage of tectonic evolution in large-scale collisional belts. The Yardoi gneiss dome is the easternmost dome of the North Himalayan Gneiss Domes (NHGD), and contains three types of amphibolites with distinct mineral assemblage, elemental and radiogenic isotope geochemistry, as well as various types of gneisses. SHRIMP zircon U/Pb analyses on the garnet amphibolite and garnet-bearing biotite granitic gneiss yield ages of nearly peak metamorphism at 45.0±1.0 Ma and 47.±1.8 Ma, respectively, which are 2 to 4 Ma older than the age for partial melting in migmatitic garnet amphibolite (43.5±1.3 Ma). Available data have demonstrated that ultra-high pressure metamorphism in the Tethyan Himalaya occurred at ∼55 Ma, and high amphibolite facies to granulite facies metamorphism at 45 to 47 Ma. In addition, partial melting at thickened crustal conditions occurred at 43.5±1.3 Ma, which led to the formation of high Sr/Y ratios two-mica granites. The high-grade metamorphic rocks in the NHGD may represent the subducted front of the Indian continental lithosphere. In large collisional belts, fertile components in crustal materials could melt and form granitic melts with relatively high Na/K and Sr/Y ratios under thickened crustal conditions, significantly different from those formed by decompressional melting during rapid exhumation. [ABSTRACT FROM AUTHOR]

High-pressure mafic granulites with a peak mineral assemblage of garnet + clinopyroxene + rutile + quartz were found in the Amdo basement, central Tibet. Two kinds of symplectites were identified that are composed of orthopyroxene + plagioclase ± spinel and hornblende + plagioclase around garnet, which were interpreted to develop during the retrogressing stages in the granulites. P-T estimates suggested that peak metamorphic conditions were about 860--920°C and 1.46--1.56 GPa, which retrogressed from post-peak phase at 820--890°C and 0.88--1.15 GPa to amphibolite facies at 550--670°C and 0.52--0.65 GPa. These three stages define a clockwise P-T path with near-isothermal decompression and cooling following the peak high-pressure metamorphism. This suggests that the Amdo granulites underwent an initial subduction to a deep crustal level of ~50 km and then were rapidly exhumed to a shallow crustal level (~20 km). The formation of Amdo granulites is considered to result from the arc-continent collision between the Amdo basement and the Qiangtang terrane in the middle Jurassic, which is a crucial step to the tectonic evolution of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Thirty samples of total suspended particles were collected at a site in western part of Lhasa, Tibet from August 2006 to July 2007. The 10Be concentrations were determined by Accelerator Mass Spectrometer (AMS). Analysis of correlation between 10Be concentrations and meteorological factors revealed that the wet scavenging has little effect on 10Be. 10Be can be used as a proxy of 10 transport processes of the upper atmosphere over the Tibetan Plateau. Analysis of correlation between 10Be concentrations and NCEP reanalysis data demonstrated that higher 10Be concentrations in spring were probably caused by the atmosphere exchange from stratosphere to troposphere during February to June. Lower 10Be concentrations during August to September were consistent with the synchronous lower O3 values, suggestive of both 10Be and O3 were probably influenced by the atmosphere exchange from troposphere to stratosphere. [ABSTRACT FROM AUTHOR]

Clear PKIKP precursors were observed from the Lanzhou CTBTO seismic array. We measured their incident angles, arriving azimuths and differential travel times with respect to the PKIKP arrivals using array analysis techniques. These measurements allowed us to locate the scatterers that generated the observed precursors. We found that the scatterers are located in the lowermost mantle beneath eastern Tibet, which is featured by a high-velocity anomaly based on previous tomographic studies. The high velocity anomaly was interpreted as the slab remnants of the ancient Tethys subduction. We thus speculate that the observed scatterers are either related or induced by the subducted slab. [ABSTRACT FROM AUTHOR]

In the "Central Uplift" of Qiangtang, Northern Tibet, a large scale of mafic dyke swarms extended in E-W direction. Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ages of 284 ± 3 Ma and 302 ± 4 Ma, respectively, suggesting they emplaced in the Late Carboniferous to Early Permian. Zircon 176Hf/177Hf ratios range from 0.282852 to 0.283041, with ϵHf(f) values of +12.1 to +12.2 and Hf modal (TDM) ages of -440-460 Ma. These data indicate that these mafic dykes were mainly derived from the depleted mantle. In addition, geochemical data suggest that these mat ic dyke swarms are of intra-plate origin. Therefore, the mafic dyke swarms represent products during the extensional process associated with the opening of the Paleo-Tethys Ocean in the area. [ABSTRACT FROM AUTHOR]

In situ zircon U-Pb ages for the recently discovered Zhunuo porphyry copper deposit in the western part of the Gangdese metallogenic belt in Tibet were determined by sensitive high-resolution ion microprobe (SHRIMP). The ages can be divided into two separate groups, reflecting more than four major tectono-magmatic events in the area. The 62.5±2.5 Ma age of inherited zircons may be related to the volcanic eruption of the Linzizong Group formed shortly after the India-Asia continental collision. The 50.1±3.6 Ma age most likely corresponds to the time of underplating of mantle-derived mafic magma in Gangdese. The 15.6±0.6 Ma age obtained from magmatic zircons is interpreted as the age of crystallization of the Zhunuo ore-forming porphyry. Finally, a molybdenite Re-Os isochron age of 13.72±0.62 Ma is consistent with another zircon U-Pb age of 13.3 ±0.2 Ma, representing the time of copper mineralization. These ages, in combination with available literature data, indicate that magmatic crystallization and copper mineralization in the Gangdese metallogenic belt became gradually younger westward, and further suggest that the Zhunuo porphyry copper deposit was formed in the same tectonic stage as other porphyry copper deposits in the eastern and central Gangdese belt. This conclusion provides critical information for future exploration of porphyry copper deposits in western Gangdese. [ABSTRACT FROM AUTHOR]

The bacterium Thermus sp. TibetanG7, isolated from hot springs in Tibet, China, was examined for the ability to accumulate cesium from solutions. Environmental conditions were simulated and the effects of pH, K+, Na+ and K+-regimes were then studied to determine the possible role of the bacterium in the formation of cesium-bearing geyserite around these hot springs. In despite of the inhibition of K+ and Na+, the bacterium Thermus sp. TibetanG7 revealed noticeable accumulation of cesium from solutions, with maximum accumulations of 53.49 and 40.41 μmol Cesium/g cell dry weight in Na+ and K+ inhibition experiments, respectively. The accumulation of cesium by this microorganism is rapid, with 40%-50% accumulated within the first 5 min. K+-deficient cells showed a much higher capacity of cesium accumulation compared with K+-sufficient cells. It is evident that the bacteria within the genus thermus play a significant role in the cesium assembly. The formation of cesium-bearing geyserite is also considered. [ABSTRACT FROM AUTHOR]

Quantitative analysis of Early Eocene radiolarian assemblages discovered in the sedimentary mélange (accretionary prism) of the Saga area, southern Tibet provides new information to constrain the timing of Tethys closure and the initial collision of India and Eurasia. The radiolarian species of Saga include Amphisphaera coronata (Ehrenberg), Buryella hannae Bak & Barwicz-Piskorz, Buryella clinata Foreman, Buryella tetradica Foreman, Calocycloma ampulla (Ehrenberg), Lamptonium fabaeforme constrictum Riedel and Sanfilippo, Lamptonium pennatum Foreman, Lithomespilus coronatus Squinabol and Lamptonium (?) colymbus Foreman. The adequate and reliable correlation of these radiolarians specimens indicates that the assemblage is of Early Eocene in age. The age and depositional environment of these radiolarians testify that deep ocean basins existed between India Plate and Asia Plate during the Early Eocene. The complete closure of Tethys must have taken place at least after the Early Eocene. [ABSTRACT FROM AUTHOR]

The Bangong Lake ophiolite is located in the westernmost part of the Bangong Lake-Nujiang River suture zone. It is a tectonic mélange consisting of numerous individual blocks of peridotite, pillowed and massive lavas and mafic dykes with SSZ-type ophiolitic geochemical affinity formed at the end of a Wilson circle. The SHRIMP U-Pb ages of the co-magmatic zircon domains from one gabbroic dyke (Sample 01Y-155) range from 162.5±8.6 Ma to 177.1±1.4 Ma with an average of 167.0±1.4 Ma (n = 12, MSWD = 1.2), suggesting that the subduction of the Bangong Lake Neo-Tethyan Ocean started before the Middle Jurassic. It is inferred that the tectonic transform from spreading to subduction of the Neo-Tethyan Ocean began before the Middle Jurassic in the Bangong Lake area. [ABSTRACT FROM AUTHOR]

Field relationship, along with petrographical, petrological, and geochemical characteristics, and zircon populations, indicates that the plagiogranites from the Lagkor Lake ophiolite in the Bangong-Nujiang suture zone (̃ 20 km south of Gerze County, central Tibet, China), derived from anatexls of hydrated gabbros by ductile shearing during transport of the oceanic crust. Therefore, this kind of plagiogranite is coeval to or little later than the spreading of the oceanic crust. Zircon SHRIMP age of 166 ± 2.5 Ma for the plagiogranites indicates that an oceanic basin existed in the western part of the Bangong-Nujiang zone In the Middle Jurassic. [ABSTRACT FROM AUTHOR]

Focuses on a study that analyzed the western boundary of extrusion blocks in the dextral slide-slip faults in the southeastern Tibetan Plateau. Geometry and kinematics of dextral strike-slip faults; Methodology of the study; Results and discussion; Conclusions.

Presents information on a study which determined the changes and evolution of the South Asian monsoon since the Last Glacial Maximum (LGM) using high-resolution fossil pollen records from small lakes in Tibetan Plateau, China. Modern pollen data set and transfer function; Reconstruction of temperature and precipitation since LGM; Discussion.

Presents information on a study which focuses on the water vapor image of snow storm process over southern Tibet, China. Insights on the snow storm process over southern Tibet on the second ten-day of November 1995; Discussion on water vapor image; Obstruct effect of the Tibetan Plateau.

Focuses on a study on the comprehensive geophysical profile and lithosphere structures and geodynamics in the Qinghai-Xizang Tibetan plateau. Density and magnetism structure; Lithosphere velocity structure and conductivity structure of the plateau area; Summary.