scholarly journals The topographic evolution of the Tibetan Region as revealed by palaeontology

2020 ◽  
Author(s):  
Robert A. Spicer ◽  
Tao Su ◽  
Paul J. Valdes ◽  
Alexander Farnsworth ◽  
Fei-Xiang Wu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Landscape Evolution ◽  
The Tibetan Plateau ◽  
Mountain Ranges ◽  
The Past ◽  
Complex Interactions ◽  
New Synthesis ◽  
The Rich ◽  
Topographic Evolution ◽  
East West

AbstractThe Tibetan Plateau was built through a succession of Gondwanan terranes colliding with Asia during the Mesozoic. These accretions produced a complex Paleogene topography of several predominantly east–west trending mountain ranges separated by deep valleys. Despite this piecemeal assembly and resultant complex relief, Tibet has traditionally been thought of as a coherent entity rising as one unit. This has led to the widely used phrase ‘the uplift of the Tibetan Plateau’, which is a false concept borne of simplistic modelling and confounds understanding the complex interactions between topography climate and biodiversity. Here, using the rich palaeontological record of the Tibetan region, we review what is known about the past topography of the Tibetan region using a combination of quantitative isotope and fossil palaeoaltimetric proxies, and present a new synthesis of the orography of Tibet throughout the Paleogene. We show why ‘the uplift of the Tibetan Plateau’ never occurred, and quantify a new pattern of topographic and landscape evolution that contributed to the development of today’s extraordinary Asian biodiversity.

scholarly journals Comprendre la dynamique atmosphérique pour mieux reconstituer l'altitude passée des chaînes de montagnes

2020 ◽  
pp. 023
Author(s):  
Svetlana Botsyun ◽  
Pierre Sepulchre ◽  
Camille Risi
Keyword(s):  
Tibetan Plateau ◽  
General Circulation ◽  
Circulation Model ◽  
Mountain Range ◽  
The Tibetan Plateau ◽  
Mountain Ranges ◽  
The Past ◽  
Il Y A ◽  
The Relationship ◽  
Composition Isotopique

Comprendre la dynamique de soulèvement d'une chaîne de montagne nécessite d'en estimer l'altitude passée. C'est le but de la paléoaltimétrie. La méthode la plus répandue utilise la composition isotopique en oxygène des roches carbonatées formées dans les sols et à partir des sédiments lacustres. Celle-ci reflète la composition de la pluie passée qui, dans le monde actuel et dans la plupart des chaînes de montagnes, s'appauvrit progressivement en isotopes lourds avec l'altitude. En supposant que cet appauvrissement reste valide dans le passé, l'altitude du plateau tibétain à l'Éocène (il y a environ 42 millions d'années) est estimée à 4 000 m environ. Mais d'autres marqueurs de l'altitude passée indiquent au contraire des altitudes inférieures à 2 000 m. La relation entre composition isotopique des pluies et altitude observée aujourd'hui s'applique-t-elle à l'Éocène ? C'est ce que nous avons essayé de vérifier en utilisant un modèle de circulation générale atmosphérique, LMDZ-iso. On trouve qu'à l'Éocène la circulation atmosphérique et les processus hydrologiques étaient tellement différents de l'actuel que les observations isotopiques dans les roches carbonatées se trouvent finalement être cohérentes avec des altitudes relativement faibles. Les différentes méthodes de paléo-altimétrie se retrouvent ainsi réconciliées et en accord avec un soulèvement récent (post-Éocène) du plateau tibétain. Understanding the uplift dynamics of a mountain range requires estimating past altitude. This is the purpose of the paleo-altimetry. The most commonly applied paleo-altimetry method is based on the isotopic oxygen composition of the carbonate archives. It reflects the composition of past rain, which at present-day and in the most mountain ranges becomes progressively more depleted in heavy isotopes with altitude. Assuming that this depletion remains valid in the past, the elevation of the Tibetan Plateau in the Eocene (about 42 millions years ago) is estimated to be about 4 000 m. However, other proxy data indicate on the contrary low altitudes. Is the relationship between the rain isotopic composition and the altitude that is observed today applicable to the Eocene? This is what we tried to verify using an atmospheric general circulation model, LMDZ-iso. We find that in the Eocene, the atmospheric circulation and hydrological processes were so different to the present-day that the isotopic observations in the Eocene carbonates are actually consistent with relatively low altitudes of the Plateau. This allows us to reconcile different methods of paleo-altimetry in agreement with more recent (post-Eocene) uplift of the Tibetan Plateau.

scholarly journals Conjugate strike-slip faulting along the Bangong-Nujiang suture zone accommodates coeval east-west extension and north-south shortening in the interior of the Tibetan Plateau

Tectonics ◽  
2003 ◽  
Vol 22 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Michael Taylor ◽  
An Yin ◽  
Frederick J. Ryerson ◽  
Paul Kapp ◽  
Lin Ding
Keyword(s):  
Tibetan Plateau ◽  
Strike Slip ◽  
Suture Zone ◽  
The Tibetan Plateau ◽  
East West

scholarly journals Diachronous Tibetan Plateau landscape evolution derived from lava field geomorphology

2020 ◽  
Author(s):  
Mark Allen ◽  
Robert Law
Keyword(s):  
Tibetan Plateau ◽  
Landscape Evolution ◽  
Tectonic Geomorphology ◽  
Normal Faults ◽  
The Tibetan Plateau ◽  
Lava Field ◽  
Northern Tibetan Plateau ◽  
Tectonic Processes ◽  
Stepwise Evolution

<p><strong>Evolution of the Tibetan Plateau is important for understanding continental tectonics because of its exceptional elevation (~5 km above sea level) and crustal thickness (~70 km). Patterns of long-term landscape evolution can constrain tectonic processes, but have been hard to quantify, in contrast to established datasets for strain, exhumation and paleo-elevation. This study analyses the relief of the bases and tops of 17 Cenozoic lava fields on the central and northern Tibetan Plateau. Analyzed fields have typical lateral dimensions of 10s of km, and so have an appropriate scale for interpreting tectonic geomorphology. Fourteen of the fields have not been deformed since eruption. One field is cut by normal faults; two others are gently folded with limb dips <6<sup>o</sup></strong><strong>. </strong><strong>Relief of the bases and tops of the fields is comparable to modern, internally-drained, parts of the plateau, and distinctly lower than externally-drained regions. The lavas preserve a record of underlying low relief bedrock landscapes at the time they were erupted, which have undergone little change since. There is an overlap in each area between younger published low-temperature thermochronology ages and the oldest eruption in each area, here interpreted as the transition </strong><strong>between the end of significant (>3 km) exhumation and plateau landscape development. </strong><strong>This diachronous process took place between ~32.5<sup>o</sup> - ~36.5<sup>o</sup> N between ~40 and ~10 Ma, advancing northwards at a long-term rate of ~15 km/Myr. Results are consistent with incremental northwards growth of the plateau, rather than a stepwise evolution or synchronous uplift.</strong></p>

scholarly journals Late Cenozoic Denudation and Topographic Evolution History of the Lhasa River Drainage in Southern Tibetan Plateau: Insights From Inverse Thermal History Modeling

2021 ◽  
Vol 9 ◽  
Author(s):  
Dongxu Cai ◽  
Xianyan Wang ◽  
Guangwei Li ◽  
Wenbin Zhu ◽  
Huayu Lu
Keyword(s):  
Tibetan Plateau ◽  
Surface Erosion ◽  
The Tibetan Plateau ◽  
Monsoon Precipitation ◽  
Late Cenozoic ◽  
River Drainage ◽  
History Of ◽  
Southern Tibetan Plateau ◽  
Lhasa River ◽  
Topographic Evolution

The interaction of surface erosion (e.g., fluvial incision) and tectonic uplift shapes the landform in the Tibetan Plateau. The Lhasa River flows toward the southwest across the central Gangdese Mountains in the southern Tibetan Plateau, characterized by a low-relief and high-elevation landscape. However, the evolution of low-relief topography and the establishment of the Lhasa River remain highly under debate. Here, we collected thermochronological ages reported in the Lhasa River drainage, using a 3D thermokinematic model to invert both late Cenozoic denudation and relief history of the Lhasa River drainage. Our results show that the Lhasa River drainage underwent four-phase denudation history, including two-stage rapid denudation at ∼25–16 Ma (with a rate of ∼0.42 km/Ma) and ∼16–12 Ma (with a rate of ∼0.72 km/Ma). In the latest Oligocene–early Miocene, uplift of the Gangdese Mountains triggered the rapid denudation and the formation of the current main drainage of the Lhasa River. In the middle Miocene, the second stage of the rapid denudation and the high relief were associated with intense incision of the Lhasa River, which is probably due to the enhanced Asian summer monsoon precipitation. This later rapid episode was consistent with the records of regional main drainage systems. After ∼12 Ma, the denudation rate decreases rapidly, and the relief of topography in the central Gangdese region was gradually subdued. This indicates that the fluvial erosion resulting from Asian monsoon precipitation increase significantly impacts on the topographic evolution in the central Gangdese region.

Extremes in the magnitude of annual temperature cycle on the Tibetan Plateau over the past three centuries

2018 ◽  
Vol 52 (5-6) ◽  
pp. 3599-3608 ◽  
Author(s):  
Jianping Duan ◽  
Zhuguo Ma ◽  
Naiming Yuan ◽  
Lun Li ◽  
Liang Chen
Keyword(s):  
Tibetan Plateau ◽  
Temperature Cycle ◽  
The Tibetan Plateau ◽  
The Past ◽  
Annual Temperature Cycle

Melting Ice Rivers

2012 ◽  
Author(s):  
Cheryl Colopy
Keyword(s):  
Global Warming ◽  
Tibetan Plateau ◽  
The Netherlands ◽  
Sea Level ◽  
The Tibetan Plateau ◽  
Mount Everest ◽  
The Past ◽  
The North ◽  
The World ◽  
The Government

From a remote outpost of global warming, a summons crackles over a two-way radio several times a week: . . . Kathmandu, Tsho Rolpa! Babar Mahal, Tsho Rolpa! Kathmandu, Tsho Rolpa! Babar Mahal, Tsho Rolpa! . . . In a little brick building on the lip of a frigid gray lake fifteen thousand feet above sea level, Ram Bahadur Khadka tries to rouse someone at Nepal’s Department of Hydrology and Meteorology in the Babar Mahal district of Kathmandu far below. When he finally succeeds and a voice crackles back to him, he reads off a series of measurements: lake levels, amounts of precipitation. A father and a farmer, Ram Bahadur is up here at this frigid outpost because the world is getting warmer. He and two colleagues rotate duty; usually two of them live here at any given time, in unkempt bachelor quarters near the roof of the world. Mount Everest is three valleys to the east, only about twenty miles as the crow flies. The Tibetan plateau is just over the mountains to the north. The men stay for four months at a stretch before walking down several days to reach a road and board a bus to go home and visit their families. For the past six years each has received five thousand rupees per month from the government—about $70—for his labors. The cold, murky lake some fifty yards away from the post used to be solid ice. Called Tsho Rolpa, it’s at the bottom of the Trakarding Glacier on the border between Tibet and Nepal. The Trakarding has been receding since at least 1960, leaving the lake at its foot. It’s retreating about 200 feet each year. Tsho Rolpa was once just a pond atop the glacier. Now it’s half a kilometer wide and three and a half kilometers long; upward of a hundred million cubic meters of icy water are trapped behind a heap of rock the glacier deposited as it flowed down and then retreated. The Netherlands helped Nepal carve out a trench through that heap of rock to allow some of the lake’s water to drain into the Rolwaling River.

Roof of the World: Tibet, Pamirs

2013 ◽  
Author(s):  
Mike Searle
Keyword(s):  
Tibetan Plateau ◽  
High Elevation ◽  
Tien Shan ◽  
Palm Tree ◽  
The Tibetan Plateau ◽  
Wet Season ◽  
North West ◽  
Mountain Ranges ◽  
The North ◽  
The World

The Tibetan Plateau is by far the largest region of high elevation, averaging just above 5,000 metres above sea level, and the thickest crust, between 70 and 90 kilometres thick, anywhere in the world. This huge plateau region is very flat—lying in the internally drained parts of the Chang Tang in north and central Tibet, but in parts of the externally drained eastern Tibet, three or four mountain ranges larger and higher than the Alps rise above the frozen plateau. Some of the world’s largest and longest mountain ranges border the plateau, the ‘flaming mountains’ of the Tien Shan along the north-west, the Kun Lun along the north, the Longmen Shan in the east, and of course the mighty Himalaya forming the southern border of the plateau. The great trans-Himalayan mountain ranges of the Pamir and Karakoram are geologically part of the Asian plate and western Tibet but, as we have noted before, unlike Tibet, these ranges have incredibly high relief with 7- and 8-kilometre-high mountains and deeply eroded rivers and glacial valleys. The western part of the Tibetan Plateau is the highest, driest, and wildest area of Tibet. Here there is almost no rainfall and rivers that carry run-off from the bordering mountain ranges simply evaporate into saltpans or disappear underground. Rivers draining the Kun Lun flow north into the Takla Makan Desert, forming seasonal marshlands in the wet season and a dusty desert when the rivers run dry. The discovery of fossil tropical leaves, palm tree trunks, and even bones from miniature Miocene horses suggest that the climate may have been wetter in the past, but this is also dependent on the rise of the plateau. Exactly when Tibet rose to its present elevation is a matter of great debate. Nowadays the Indian Ocean monsoon winds sweep moisture-laden air over the Indian sub-continent during the summer months (late June–September). All the moisture is dumped as the summer monsoon, the torrential rains that sweep across India from south-east to north-west.

Acricotopus indet. morphotype incurvatus: Description and genetics of a new Orthocladiinae (Diptera: Chironomidae) larval morphotype from the Tibetan Plateau

Zootaxa ◽  
2019 ◽  
Vol 4656 (3) ◽  
pp. 535-544
Author(s):  
ANDREAS LAUG ◽  
LADISLAV HAMERLÍK ◽  
STEN ANSLAN ◽  
STEFAN ENGELS ◽  
FALKO TURNER ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Mitochondrial Coi ◽  
Mountain Ranges ◽  
Central Tibetan Plateau ◽  
Peculiar Form ◽  
Close Proximity ◽  
Coi Sequences ◽  
Complex Formations

High mountain ranges such as the Tibetan Plateau with an average altitude above 4500 m are topographically complex formations. Elevational gradients, physiographic diversity and climatic heterogeneity have led to highly biodiverse ecosystems in these regions. Mountain ranges can be seen as cradles of evolution and harbour, due to their unique characteristics, a high number of highly adapted species. At the same time these areas are hard to access and therefore taxonomic information is limited. Here we describe a new Acricotopus (Diptera: Chironomidae: Orthocladiinae) larval morphotype occurring in lakes and ponds of differing salinity and water depths located on the Southern and Central Tibetan Plateau. The description is based on larvae and their genetics (ribosomal 18S, 28S and mitochondrial COI sequences) collected from a shallow pond in close proximity to the large saline lake Selin Co. Larvae of Acricotopus indet. morphotype incurvatus are characterized by a mentum with a cluster of lateral teeth, partially folded inwards, a mandible with a toothed lobe in addition to four inner teeth and a sclerotized plate positioned behind the mentum. Up to now, these morphological features have only been found in early instars of other Acricotopus species. The proposed morphotype name is inspired by the peculiar form of the mentum. 

Lake variations in response to climate change in the Tibetan Plateau in the past 40 years

2013 ◽  
Vol 6 (6) ◽  
pp. 534-549 ◽  
Author(s):  
Jingjuan Liao ◽  
Guozhuang Shen ◽  
Yingkui Li
Keyword(s):  
Climate Change ◽  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
The Past
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