scholarly journals Early Cenozoic Multiple Thrust in the Tibetan Plateau

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Zhenhan Wu ◽  
Peisheng Ye ◽  
Patrick J. Barosh ◽  
Daogong Hu ◽  
Lu Lu
Keyword(s):  
Tibetan Plateau ◽  
Late Eocene ◽  
Geological Mapping ◽  
Early Miocene ◽  
Crustal Thickening ◽  
The Tibetan Plateau ◽  
Continental Plate ◽  
Thrust Sheets ◽  
Lower Crustal ◽  
Early Cenozoic

Recently completed regional geological mapping at a scale of 1 : 250,000 or larger across all of the Tibetan Plateau coupled with deep seismic surveys reveals for the first time a comprehensive depiction of the major early Cenozoic thrust systems resulting from the northward subduction of the Indian Continental Plate. These systems define a series of overlapping north-dipping thrust sheets that thickened the Tibetan crust and lead to the rise of the plateau. The few south-dipping thrusts present apparently developed within a sheet when the back moved faster than the toe. Many of the thrusts are shown to extend to the middle-lower crustal depths by seismic data. The regional thrust systems are the Main Central, Renbu-Zedong, Gangdese, Central Gangdese, North Gangdese, Bangoin-Nujiang, Qiangtang, Hohxil, and South Kunlun Thrusts. The minimal southward displacements of the South Kunlun, Hohxil, South Qiangtang, and Central Gangdese Thrusts are estimated to be 30 km, 25 km, 150 km and 50 km, respectively. Deep thrusting began in the Himalaya-Tibetan region soon after India-Eurasia continental collision and led to crustal thickening and subsequent uplift of the Tibetan Plateau during Late Eocene-Early Miocene when the systems were mainly active. The major thrust systems ceased moving in Early Miocene and many were soon covered by lacustrine strata. This activity succeeded in the late Cenozoic to crustal extension and strike-slip movement in the central Tibetan Plateau. The revelation of the full array of the early Cenozoic thrust systems provides a much more complete understanding of the tectonic framework of the Tibetan Plateau.

Incision migration across Eastern Tibet controlled by monsoonal climate, not tectonics?

2020 ◽  
Author(s):  
Katharine Groves ◽  
Mark Allen ◽  
Christopher Saville ◽  
Martin Hurst ◽  
Stuart Jones
Keyword(s):  
Tibetan Plateau ◽  
Transition Zone ◽  
Channel Flow ◽  
East Asian Monsoon ◽  
Crustal Thickening ◽  
Mean Annual Precipitation ◽  
The Tibetan Plateau ◽  
Geomorphic Indices ◽  
Hypsometric Integral ◽  
Early Cenozoic

<p>The formation and uplift history of the Tibetan Plateau, driven by the India-Eurasia collision, is the subject of intense research. Geomorphic indices capture the landscape response to competition between climate and tectonics and reflect the spatial distribution of erosion. We analyse the link between climate and tectonics in the eastern part of the Tibetan Plateau using the mean annual precipitation, digital elevation data, and by calculating the geomorphic indices hypsometric integral (HI), surface roughness (SR) and elevation relief ratio (ZR). This is a region where competing tectonic models suggest either early Cenozoic plateau growth, or a late phase of crustal thickening, surface uplift and plateau growth driven by lower crustal flow (“channel flow”).</p><p>Swath profiles of rainfall, elevation and the geomorphic indices were constructed, orthogonal to the internal drainage boundary. Each profile was analysed to find the location of maximum change in trend. A broad transition zone is present in the landscape, where changes in landscape and precipitation are grouped and in alignment. The zone cuts across structural boundaries. It represents, from East to West, a sharp decline in precipitation below ~650 mm/yr (interpreted as the western extent of the East Asian monsoon), a change from a high relief landscape to smoother elevations at 4500-5000 m, a transition to low HI (< 0.05), a decrease in SR and an increase in ZR. This zone is not a drainage divide: the main rivers have their headwaters further West, in the interior of the plateau.</p><p>We argue that this geomorphic-climatic transition zone represents a change from incised to non-incised landscapes, the location of which is controlled by the western extent of the monsoon. Published low temperature thermochronology data suggest the plateau had reached its modern extent at the Eocene, but has been exhumed since ~15 Ma to the East of the transition zone, at least along major drainage networks. We therefore also suggest that the transition zone is the current position of a long-term wave of incision that has migrated from East to West, driven by late Cenozoic intensification of the monsoon climate. This work supports a model of early Cenozoic growth of the eastern Tibetan Plateau, superimposed by incision driven by climate change; it does not support the channel flow model.</p>

Monsoon-driven incision and exhumation of the Eastern Tibetan Plateau

2021 ◽  
Author(s):  
Katharine Groves ◽  
Mark Allen ◽  
Christopher Saville ◽  
Martin Hurst ◽  
Stuart Jones
Keyword(s):  
Tibetan Plateau ◽  
Channel Flow ◽  
Crustal Thickening ◽  
Mean Annual Precipitation ◽  
The Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
Geomorphic Indices ◽  
Surface Uplift ◽  
Hypsometric Integral ◽  
Early Cenozoic

<p>The formation and uplift history of the Tibetan Plateau, driven by the India-Eurasia collision, is the subject of intense research. We analyse the link between climate and tectonics in the central and eastern Tibetan Plateau using geomorphic indices of surface roughness (SR) hypsometric integral (HI) and elevation-relief ratio (ZR) and mean annual precipitation, thermochronology and erosion rate data. Geomorphic indices capture the landscape response to competition between climate and tectonics and reflect the spatial distribution of erosion. This is a region where competing tectonic models suggest either early Cenozoic plateau growth, or a late phase of crustal thickening, surface uplift and plateau growth driven by lower crustal flow (“channel flow”). Swath profiles of rainfall, elevation and the geomorphic indices were constructed, orthogonal to the internal drainage boundary. Each profile was analysed to find the location of maximum change in trend. We identify a broad ˜WSW-ENE trending transition in the landscape where changes in landscape and precipitation are grouped and in alignment. It represents, from east to west, a sharp decline in precipitation (interpreted as the western extent of the East Asian monsoon), a change to a low relief landscape at 4500-5000 m elevation, an increase in ZR and a transition to low HI and SR. This zone cuts across structural boundaries and is not a drainage divide: the main rivers have their headwaters further West, in the interior of the plateau. We argue that this geomorphic-climatic transition zone represents a change from incised to non-incised landscapes, the location of which is controlled by the western extent of the monsoon. Modern erosion rates are lower in the non-incised region, west of the monsoon extent (mean 0.02 mm/yr), than the incised region (mean 0.26 mm/yr). Compiled thermochronology data shows an increase in exhumation from ˜25 Ma in the incised area but no evidence of this increased exhumation in the non-incised area. This pattern supports a model of early Cenozoic growth of the eastern Tibetan Plateau, superimposed by incision driven by Miocene monsoon intensification. Our results do not support the channel flow model, which would predict an eastwards wave of surface uplift and therefore erosion and exhumation during the Miocene, which are not present in the data.</p>

Crustal thickening and uplift of the Qiangtang Terrane, Tibetan Plateau during the Late Cretaceous to Early Palaeocene: geochronology and geochemistry of the Saiduopugangri granite

2020 ◽  
Author(s):  
xue li ◽  
Guo-Sheng Sun ◽  
Gen-Yi Liu ◽  
Huan Zhou ◽  
Zi-Ling Shan ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Cretaceous ◽  
Crustal Thickening ◽  
Magma Source ◽  
Geodynamic Setting ◽  
The Tibetan Plateau ◽  
Weighted Mean ◽  
Lower Crustal ◽  
Qiangtang Terrane ◽  
Shoshonitic Series

There continues to be debate regarding the timing of the collision between the Indian and Eurasian plates and the uplift of the Tibetan Plateau. This study presents zircon U–Pb geochronology, whole-rock geochemistry, and Lu–Hf isotopic data for the Saiduopugangri granite of the Qiangtang Terrane, located within the core of the Tibetan Plateau. These data provide the basis for the geodynamic setting, petrogenesis, and characteristics of its magma source. Zircons from the Saiduopugangri granite yield a weighted-mean 206Pb/238U age of 62.72 ± 0.06 Ma, indicating that these rocks formed during the early Palaeocene. The rocks are members of the highly calc-alkaline to shoshonitic series, with weak peraluminous characteristics. Trace elements are characterised by high Sr (483–616ppm), and low Y (6–10ppm) and Yb (1ppm) content, typical of a high Sr and low Yb granite. The εHf(t) of zircon range from −2.14 to 2.35, with two-stage Hf model ages (TDM2) ranging from 1182 to 895Ma. These data suggest that the Saiduopugangri granite magma was derived from the melting of lower-crustal clastic meta-sedimentary rocks and mantle-derived basalts. The high Sr and low Yb granite characteristics and experimental results indicate that melting occurred at >1.2 GPa and >750 °C, consistent with a crustal thickness greater than 50km. Magmatism occurred from the Late Cretaceous to the early Palaeogene and is broadly synchronous with the collision timing between the Indian and Eurasian plates. The Saiduopugangri granite provides evidence of crustal thickening of the Tibetan Plateau and its age and petrogenesis constrain the timing of the initial uplift.

Late Eocene post-collisional magmatic rocks from the southern Qiangtang terrane record the melting of pre-collisional enriched lithospheric mantle

2021 ◽  
Author(s):  
Yue Qi ◽  
Qiang Wang ◽  
Gang-jian Wei ◽  
Xiu-Zheng Zhang ◽  
Wei Dan ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Trace Element ◽  
Partial Melting ◽  
Early Cretaceous ◽  
Lithospheric Mantle ◽  
Late Eocene ◽  
The Tibetan Plateau ◽  
Mafic Rocks ◽  
Isotopic Compositions ◽  
Qiangtang Terrane

Diverse rock types and contrasting geochemical compositions of post-collisional mafic rocks across the Tibetan Plateau indicate that the underlying enriched lithospheric mantle is heterogeneous; however, how these enriched mantle sources were formed is still debated. The accreted terranes within the Tibetan Plateau experienced multiple stages of evolution. To track the geochemical characteristics of their associated lithospheric mantle through time, we can use mantle-derived magmas to constrain the mechanism of mantle enrichment. We report zircon U-Pb ages, major and trace element contents, and Sr-Nd isotopic compositions for Early Cretaceous and late Eocene mafic rocks in the southern Qiangtang terrane. The Early Cretaceous Baishagang basalts (107.3 Ma) are characterized by low K2O/Na2O (<1.0) ratios, arc-like trace element patterns, and uniform Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7067−0.7073, εNd(t) = −0.4 to −0.2]. We suggest that the Baishagang basalts were derived from partial melting of enriched lithospheric mantle that was metasomatized by subducted Bangong−Nujiang oceanic material. We establish the geochemistry of the pre-collisional enriched lithospheric mantle under the southern Qiangtang terrane by combining our data with those from other Early Cretaceous mafic rocks in the region. The late Eocene (ca. 35 Ma) post-collisional rocks in the southern Qiangtang terrane have low K2O/Na2O (<1.0) ratios, and their major element, trace element, and Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7042−0.7072, εNd(t) = −4.5 to +1.5] are similar to those of the Early Cretaceous mafic rocks. Based on the distribution, melting depths, and whole-rock geochemical compositions of the Early Cretaceous and late Eocene mafic rocks, we argue that the primitive late Eocene post-collisional rocks were derived from pre-collisional enriched lithospheric mantle, and the evolved samples were produced by assimilation and fractional crystallization of primary basaltic magma. Asthenosphere upwelling in response to the removal of lithospheric mantle induced the partial melting of enriched lithospheric mantle at ca. 35 Ma.

The role of pre-existing weak zones in the formation of the Himalaya and Tibetan plateau: 3-D thermomechanical modelling

2020 ◽  
Vol 221 (3) ◽  
pp. 1971-1983
Author(s):  
Lin Chen ◽  
Lijun Liu ◽  
Fabio A Capitanio ◽  
Taras V Gerya ◽  
Yang Li
Keyword(s):  
Tibetan Plateau ◽  
Early Stage ◽  
Crustal Thickening ◽  
The Tibetan Plateau ◽  
Crustal Material ◽  
Weak Zone ◽  
Orogenic Wedge ◽  
Orogenic Plateau ◽  
Weak Zones

SUMMARY The Tibetan crust is sliced by several east–west trending suture zones. The role of these suture zones in the evolution of the Himalayan range and Tibetan plateau remains unclear. Here we use 3-D thermomechanical simulations to investigate the role of pre-existing weak zones within the Asian Plate in the formation of orogen and plateau growth during continental collision. Our results show that partitioning of deformation along the convergent margin leads to scraping off of crustal material into an orogenic wedge above the margin and crustal thickening in the retro-continent, eventually forming a large orogenic plateau in front of the indenter. Pre-existing weak zone(s) within the retro-continent is reactivated at the early stage of convergence, and facilitates the northward propagation of strain and widening of the orogenic plateau. The northernmost weak zone sets the northern limit of the Tibetan plateau. Our models also show rheological weakening of the congested buoyant crust within the collisional zone drives wedge-type exhumation of deeply buried crust at the southern flank of the plateau, which may explain the formation of the Greater Himalayan Sequence.

Early Cenozoic Tectonics of the Tibetan Plateau

2013 ◽  
Vol 87 (2) ◽  
pp. 289-303 ◽  
Author(s):  
WU Zhenhan ◽  
HU Daogong ◽  
YE Peisheng ◽  
WU Zhonghai
Keyword(s):  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Cenozoic Tectonics ◽  
Early Cenozoic

Late Triassic orogenic assembly of the Tibetan Plateau: constraints from magmatism and metamorphism in the east Lhasa terrane

2021 ◽  
Author(s):  
Yanfei Chen ◽  
Zeming Zhang ◽  
Richard M Palin ◽  
Zuolin Tian ◽  
Hua Xiang ◽  
...  
Keyword(s):  
Crustal Thickening ◽  
Late Triassic ◽  
The Tibetan Plateau ◽  
Plate Convergence ◽  
Lhasa Terrane ◽  
The North ◽  
Tectonic History ◽  
Peak Metamorphism ◽  
Tethys Ocean ◽  
Lower Crustal

Abstract The early Mesozoic evolution of the Lhasa terrane, which represents a major component of the Himalayan-Tibetan orogen, remains highly controversial. In particular, geological units and events documented either side of the eastern Himalayan syntaxis (EHS) are poorly correlated. Here, we report new petrological, geochemical and geochronological data for co-genetic peraluminous S-type granites and metamorphic rocks (gneiss and schist) from the Motuo–Bomi–Chayu region of the eastern Lhasa terrane, located on the eastern flank of the EHS. Zircon U–Pb dating indicates that these units record both Late Triassic magmatic (216–206 Ma) and metamorphic (209–198 Ma) episodes. The granites were derived from a Paleoproterozoic crustal source with negative zircon εHf(t) values (–5.5 to –16.6) and TDM2 model ages of 1.51–1.99 Ga, and are interpreted to have formed by crustal anatexis of nearby metasediments during collisional orogeny and crustal thickening. The gneisses and schists experienced similar upper amphibolite-facies peak metamorphism and associated partial melting, followed by decompressional cooling and retrograde metamorphism. These rocks were buried to lower-crustal depths and then exhumated to the surface in a collisional orogenic setting during plate convergence. From comparison of these data to other metamorphic belts with similar grades and ages, and association of coeval granitic magmatism widespread in the central-east Lhasa terrane, we propose that the studied co-genetic magmatism and metamorphism in the Motuo–Bomi–Chayu region records Late Triassic accretion of the North Lhasa and South Lhasa terranes, which represents the first evidence of the Paleo-Tethys ocean (PTO) closure in this part of Asia. These data provide new constraints on the spatial and temporal evolution of the Paleo-Tethyan Wilson Cycle and provide a ‘missing link’ to correlate the geology and tectonic history of the Lhasa terrane continental crust on either side of the EHS.

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