Crustal thickness and upper mantle velocities in the Tibetan Plateau Region from the inversion of regionalPnlwaveforms: Evidence for a thick upper mantle lid beneath southern Tibet

1990 ◽  
Vol 95 (B8) ◽  
pp. 12499 ◽  
Author(s):  
William E. Holt ◽  
Terry C. Wallace
Keyword(s):  
Tibetan Plateau ◽  
Upper Mantle ◽  
Crustal Thickness ◽  
The Tibetan Plateau ◽  
Plateau Region ◽  
Southern Tibet

scholarly journals Lithospheric structures of and tectonic implications for the central–east Tibetan plateau inferred from joint tomography of receiver functions and surface waves

2020 ◽  
Vol 223 (3) ◽  
pp. 1688-1707
Author(s):  
Mei Feng ◽  
Meijian An ◽  
James Mechie ◽  
Wenjin Zhao ◽  
Guangqi Xue ◽  
...  
Keyword(s):  
Surface Wave ◽  
Tibetan Plateau ◽  
Wave Velocity ◽  
Upper Mantle ◽  
High Velocity ◽  
Crustal Thickness ◽  
Receiver Functions ◽  
The Tibetan Plateau ◽  
S Wave ◽  
East Kunlun

SUMMARY We present an updated joint tomographic method to simultaneously invert receiver function waveforms and surface wave dispersions for a 3-D S-wave velocity (Vs) model. By applying this method to observations from ∼900 seismic stations and with a priori Moho constraints from previous studies, we construct a 3-D lithospheric S-wave velocity model and crustal-thickness map for the central–east Tibetan plateau. Data misfit/fitting shows that the inverted model can fit the receiver functions and surface wave dispersions reasonably well, and checkerboard tests show the model can retrieve major structural information. The results highlight several features. Within the plateau crustal thickness is >60 km and outwith the plateau it is ∼40 km. Obvious Moho offsets and lateral variations of crustal velocities exist beneath the eastern (Longmen Shan Fault), northern (central–east Kunlun Fault) and northeastern (east Kunlun Fault) boundaries of the plateau, but with decreasing intensity. Segmented high upper-mantle velocities have varied occurrences and depth extents from south/southwest to north/northeast in the plateau. A Z-shaped upper-mantle low-velocity channel, which was taken as Tibetan lithospheric mantle, reflecting deformable material lies along the northern and eastern periphery of the Tibetan plateau, seemingly separating two large high-velocity mantle areas that, respectively, correspond to the Indian and Asian lithospheres. Other small high-velocity mantle segments overlain by the Z-shaped channel are possibly remnants of cold microplates/slabs associated with subductions/collisions prior to the Indian–Eurasian collision during the accretion of the Tibetan region. By integrating the Vs structures with known tectonic information, we derive that the Indian slab generally underlies the plateau south of the Bangong–Nujiang suture in central Tibet and the Jinsha River suture in eastern Tibet and west of the Lanchangjiang suture in southeastern Tibet. The eastern, northern, northeastern and southeastern boundaries of the Tibetan plateau have undergone deformation with decreasing intensity. The weakly resisting northeast and southeast margins, bounded by a wider softer channel of uppermost mantle material, are two potential regions for plateau expansion in the future.

A lake-level chronology based on feldspar luminescence dating of beach ridges at Tangra Yum Co (Southern Tibet)

2015 ◽  
Vol 83 (3) ◽  
pp. 469-478 ◽  
Author(s):  
Eike F. Rades ◽  
Sumiko Tsukamoto ◽  
Manfred Frechen ◽  
Qiang Xu ◽  
Lin Ding
Keyword(s):  
Tibetan Plateau ◽  
Lake Level ◽  
Environmental Changes ◽  
Luminescence Dating ◽  
Rapid Decline ◽  
The Tibetan Plateau ◽  
Southern Tibet ◽  
Beach Ridges ◽  
Slow Decline ◽  
Fast Decline

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.

scholarly journals Transport of Asian surface pollutants to the global stratosphere from the Tibetan Plateau region during the Asian summer monsoon

2020 ◽  
Vol 7 (3) ◽  
pp. 516-533 ◽  
Author(s):  
Jianchun Bian ◽  
Dan Li ◽  
Zhixuan Bai ◽  
Qian Li ◽  
Daren Lyu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Global Climate ◽  
Pollutant Emissions ◽  
The Tibetan Plateau ◽  
Plateau Region ◽  
Radiative Processes ◽  
Asian Summer ◽  
The Impact

Abstract Due to its surrounding strong and deep Asian summer monsoon (ASM) circulation and active surface pollutant emissions, surface pollutants are transported to the stratosphere from the Tibetan Plateau region, which may have critical impacts on global climate through chemical, microphysical and radiative processes. This article reviews major recent advances in research regarding troposphere–stratosphere transport from the region of the Tibetan Plateau. Since the discovery of the total ozone valley over the Tibetan Plateau in summer from satellite observations in the early 1990s, new satellite-borne instruments have become operational and have provided significant new information on atmospheric composition. In addition, in situ measurements and model simulations are used to investigate deep convection and the ASM anticyclone, surface sources and pathways, atmospheric chemical transformations and the impact on global climate. Also challenges are discussed for further understanding critical questions on microphysics and microchemistry in clouds during the pathway to the global stratosphere over the Tibetan Plateau.

Seismic Anisotropy of Upper Mantle in the Northeastern Margin of the Tibetan Plateau

2008 ◽  
Vol 51 (2) ◽  
pp. 298-306 ◽  
Author(s):  
Li-Jun CHANG ◽  
Chun-Yong WANG ◽  
Zhi-Feng DING ◽  
Min-Du ZHOU ◽  
Jian-Si YANG ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Upper Mantle ◽  
Seismic Anisotropy ◽  
The Tibetan Plateau

scholarly journals Microplastics Footprints in a High-Altitude Basin of the Tibetan Plateau, China

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2805
Author(s):  
Sansan Feng ◽  
Hongwei Lu ◽  
Tianci Yao
Keyword(s):  
Tibetan Plateau ◽  
Surface Waters ◽  
Human Activities ◽  
The Tibetan Plateau ◽  
Brahmaputra River ◽  
Plateau Region ◽  
Remote Areas ◽  
Water And Sediment ◽  
Lhasa River ◽  
And Behavior

Microplastics (MPs) are ubiquitous in the environment and have been drawing increasing attention; however, MPs’ occurrence and behavior in remote areas are not well understood. In this study, we quantified and characterized MPs from surface waters and sediments in a remote area, namely the Tibetan Plateau, China. The samples were collected from the Lhasa River and the lower reaches of the Brahmaputra River to better understand MPs’ sources to rivers of the Tibetan Plateau. MPs’ concentrations in water and sediment were 735 items/m3 and 51 items/kg, respectively, and the dominating MPs observed were fibers with size ranging from 100 to 500 µm. MP abundance increased nearly two-fold from upstream to downstream in the Brahmaputra River, associated with the inputs from downstream human activities and the inflows of tributaries (especially the Lhasa River). This study provides important bases for analyzing MPs migration processes in the plateau region.

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