scholarly journals Rapid Eocene Exhumation of the West Qinling Belt: Implications for the Growth of the Northeastern Tibetan Plateau

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Yi-Peng Zhang ◽  
Wen-Jun Zheng ◽  
Wei-Tao Wang ◽  
Yun-Tao Tian ◽  
Renjie Zhou ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Hanging Wall ◽  
The Tibetan Plateau ◽  
Collision System ◽  
The West ◽  
Crustal Shortening ◽  
Late Mesozoic ◽  
West Qinling ◽  
Northeastern Tibetan Plateau ◽  
Thermal Histories

Abstract Cenozoic exhumation in the northeastern Tibetan Plateau provides insights into spatial-temporal patterns of crustal shortening, erosion, landscape evolution, and geodynamic drivers in the broad India-Eurasia collision system. The NW-SE trending West Qinling Belt has been a central debate as to when crustal shortening took place. Within the West Qinling Belt, a thick succession of Cretaceous sedimentary rocks has been deformed and exhumed along major basin-bounding thrust faults. We present new apatite (U-Th)/He ages from the hanging wall and footwall of this major thrust. Contrasting thermal histories show that rapid cooling commenced as early as ca. 45 Ma and continued for 15–20 Myr for the hanging wall, whereas the footwall experiences continuous cooling and slow exhumation since the late Mesozoic. We infer that accelerated exhumation was driven by thrusting in response to the northward growth of the Tibetan Plateau during the Eocene (ca. 45–35 Ma) based on regional sedimentological, structural, and thermochronological data.

scholarly journals Integrated Geophysical Evidence for the Middle-Lower Crust Melting of the Songpan-Aba Terrain, NE Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Chongjin Zhao ◽  
Luolei Zhang ◽  
Peng Yu ◽  
Xi Xu
Keyword(s):  
Tibetan Plateau ◽  
Magnetic Layer ◽  
Orogenic Belt ◽  
The Tibetan Plateau ◽  
The West ◽  
Magnetotelluric Data ◽  
West Qinling ◽  
The North ◽  
Weakly Magnetic ◽  
Surrounding Areas

The Songpan−Aba region is located on the northeastern edge of the Tibetan Plateau. Tectonically, the area is surrounded by the West Qinling orogenic belt in the north, the Longmenshan orogenic belt in the southeast, and the East Kunlun and Sanjiang orogenic belts in the west and southwest, forming a triangle that provides an ideal location to study the crust-mantle structure and deep tectonics of the eastward extrusion of the Tibetan Plateau. In this study, the magnetic and electrical structures of the Songpan−Aba area were investigated by inversion using high-precision magnetic anomaly and magnetotelluric data to obtain the subsurface magnetization inversion intensity and resistivity of Songpan–Aba and adjacent areas. The results revealed a continuous magnetic layer up to 20 km below Songpan–Aba and its surrounding areas in the south, possibly originating from a magma root southwest of the Longmenshan massif. In the West Qinling, Songpan–Aba, and Longmenshan areas, pervasive low-resistance, weakly magnetic, or magnetic layers were identified below 20 km that might be formed from the molten mantle material extruded from the eastern edge of the Tibetan Plateau.

scholarly journals Late Miocene hinterland crustal shortening in the Longmen Shan thrust belt, the eastern margin of the Tibetan Plateau

2020 ◽  
Author(s):  
Xiaoming Shen ◽  
Yuntao Tian ◽  
Shimin Zhang ◽  
Andrew Carter ◽  
Barry Kohn ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Miocene ◽  
Hanging Wall ◽  
The Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
Crustal Shortening ◽  
2008 Wenchuan Earthquake ◽  
Slip History ◽  
History Of ◽  
Geodynamic Models

<p>Long‐term (million year time scale) fault‐slip history is crucial for understanding the processes and mechanisms of mountain building in active orogens. Such information remains elusive in the Longmen Shan, the eastern Tibetan Plateau margin affected by the devastating 2008 Wenchuan earthquake. While this event drew attention to fault deformation on the foreland side (the Yingxiu‐Beichuan fault), little is known about the deformation history of the hinterland Wenchuan‐Maoxian fault. To address this gap, thermochronological data were obtained from two vertical transects from the Xuelongbao massif, located in the hanging wall of the Wenchuan‐Maoxian fault. The data record late Miocene rapid cooling and rock exhumation at a rate of 0.9–1.2 km/m.y. from ~13 Ma to present. The exhumation rate is significantly higher than that in the footwall (~0.3–0.5 km/m.y.), indicating a differential exhumation of ~0.6 km/m.y. across the fault. This differential exhumation provides the first and minimum constraint on the long‐term throw rate (~0.6 km/m.y) of the Wenchuan‐Maoxian fault since the late Miocene. This new result implies continuous crustal shortening along the hinterland fault of Longmen Shan, even though it has not been ruptured by major historic earthquakes. Our study lends support to geodynamic models that highlight crustal shortening as dominating deformation along the eastern Tibetan Plateau.</p>

scholarly journals Strain Transformation Adjacent to the West Qinling Orogen: Implications for the Growth of the Northeastern Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhangjun Li ◽  
Feng Cheng ◽  
Ming Hao ◽  
Zachary M. Young ◽  
Shangwu Song ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Crustal Deformation ◽  
Deformation Pattern ◽  
Qinling Orogen ◽  
The West ◽  
West Qinling ◽  
Vertical Land Motion ◽  
Northeastern Tibetan Plateau ◽  
Strain Transformation ◽  
West Qinling Orogen

The West Qinling orogen has played an important role in accommodating the deformation in the northeastern Tibetan Plateau induced by the India-Eurasia convergence. Here we construct a vertical land motion (VLM) model based on the latest leveling observations adjacent to the West Qinling orogen. Combined with the horizontal deformation field, the crustal deformation pattern in this area is investigated. Additionally, slip rate and coupling coefficients of the West Qinling fault, the longest fault separating the West Qinling orogen from the Lanzhou (Longxi) block, are inverted and constrained with GPS and VLM observations. Results show that the West Qinling fault slips slowly at a rate of 1–2 mm/yr and is strongly coupled with a moment magnitude deficit of Mw7.4. The crustal uplift rates adjacent to the West Qinling orogen are 0–3 mm/yr; which combined with 0–12.5 × 10−9/yr contraction rates, suggests that strain transformation plays a key role in controlling the tectonic uplift in the West Qinling orogen, and furthers our understanding of the contemporary geomorphic and topographic features. We identify a significant deformation transition belt at longitudes of 105°–106°E, which indicates that crustal deformation, induced from the northeastern expansion of the Tibetan Plateau, is mainly constrained to the plateau, rather than accommodated by crustal materials escaping eastward along the Qinling Mountains.

Marine Isotope Stage 3 paleotemperature inferred from reconstructing the Die Shan ice cap, northeastern Tibetan Plateau

2018 ◽  
Vol 89 (2) ◽  
pp. 494-504 ◽  
Author(s):  
Hang Cui ◽  
Jie Wang ◽  
Beibei Yu ◽  
Zhenbo Hu ◽  
Pan Yao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Marine Isotope Stage ◽  
The Tibetan Plateau ◽  
Equilibrium Line Altitude ◽  
Last Glacial ◽  
Mis 3 ◽  
Ice Cap ◽  
Northeastern Tibetan Plateau

AbstractGlacial extent mapping and dating indicate that the local last glacial maximum (LLGM) of the northeastern Tibetan Plateau occurred during mid-Marine Isotope Stage (MIS) 3. This is asynchronous with the global last glacial maximum (LGM) that occurred during MIS 2. The causes underlying this asynchronicity are the subject of ongoing debate, and paleoclimatic reconstructions are a key to advancing understanding of the climatic influence on the spatial and temporal patterns of paleoglaciation. We used multiple methods to reconstruct the equilibrium-line altitude (ELA) of the Die Shan paleo-ice cap on the northeastern Tibetan Plateau, and to infer past temperature for ice maximum positions believed to be mid-MIS 3 in age, based on regional correlation. Geomorphic ELA reconstructions combined with an energy and mass balance model yield a paleo-ELA of 4117±31 m asl (786 m lower than present) with temperature depressions of 3.8 to ~4.6°C compared to the present. This is less than the LGM reconstruction of temperature depression inferred from other climatic proxy records on the Tibetan Plateau and suggests that the LLGM glacial advance was a product of lower temperatures and slightly reduced precipitation compared to present, whereas the LGM was a more restricted advance in which much colder conditions were combined with much lower precipitation.

A comparative study of radiocarbon dating on terrestrial organisms and fish from Qinghai Lake in the northeastern Tibetan Plateau, China

The Holocene ◽  
2018 ◽  
Vol 28 (11) ◽  
pp. 1712-1719 ◽  
Author(s):  
E ChongYi ◽  
YongJuan Sun ◽  
XiangJun Liu ◽  
Guangliang Hou ◽  
ShunChang Lv ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Holocene ◽  
Sediment Cores ◽  
Qinghai Lake ◽  
The Tibetan Plateau ◽  
Fish Bones ◽  
Northeastern Tibetan Plateau ◽  
Animal Bones ◽  
Gymnocypris Przewalskii ◽  
The Difference

Qinghai Lake is the largest lake on the Tibetan Plateau (TP) and in China and has been a focus of paleoenvironmental and climatic research for decades. However, limited understanding of lake 14C reservoir effects (LRE) has led to inconsistent interpretations among proxies of different sediment cores. As such, the onset of LRE variability during the Holocene is still unclear. 14C dating of archeological samples from four locations (Gangcha, Shaliuheqiaoxi, and Shinaihai sites, and Niaodao section) including naked carp ( Gymnocypris przewalskii, Kessler) fish bones, animal bones and teeth, and charcoal was employed to estimate variations in LRE over the last few thousand years. LRE offsets calculated as the difference between LRE of animal bones and fish bones are more reliable than that of charcoal and fish bones due to the ‘old wood’ effect in charcoal. LRE offsets recorded in fish bones were ~0.5, ~0.6, and ~0.7 ka during the periods of 3.0–3.4 cal ka BP, 0.58–0.60 cal ka BP, and modern lake times, respectively, which may indicate a temporal minimum LRE offset. Unlike the wide spatial variations of LRE ages obtained from surface total organic carbon (TOC) samples of the modern Qinghai Lake, LRE offsets from the three contemporaneous locations in Qinghai Lake were all ~0.5 ka, suggesting efficient carbon mixing occurred in naked carp. However, the late-Holocene (~3.1 ka BP) LRE increased slightly with increasing salinity and decreasing lake level.

Early Eocene rapid exhumation record in the region of Nima, central Tibet, as determined by low-temperature thermochronology

2020 ◽  
Author(s):  
Weiwei Xue ◽  
Yani Najman ◽  
Xiumian Hu ◽  
Cristina Persano ◽  
Finlay M. Stuart ◽  
...  
Keyword(s):  
Earth Sciences ◽  
Tibetan Plateau ◽  
Low Temperature ◽  
Hanging Wall ◽  
Published Data ◽  
The Tibetan Plateau ◽  
History Of ◽  
Central Tibet ◽  
Inversion Modelling ◽  
Early Paleogene

<p>Knowledge of the geological history of the Tibetan plateau is critical to understanding crustal deformation process, and the plateau’s influence on climate. However, the timing of Tibetan plateau development remains controversial. The Nima Basin along the Jurassic-Cretaceous Bangong Suture in central Tibet provides well-dated records of exhumation in this area. Here, we present detrital zircon U-Pb, apatite U-Th/He (AHe) and apatite fission track data (AFT) from upper Cretaceous and Oligocene red sandstones and conglomerates in the Nima Basin, as well as from the Xiabie granite in the hanging wall of the basin-bounding Muggar Thrust. 4 granite conglomerate clasts from the above yield zircon U-Pb ages ranging between 114-122 Ma, which likely come from the Xiabie granite. 7 granitoid/sandstone conglomerate clasts yield AHe ages ranging from 21-58 Ma, while AFT ages range from 34-83 Ma. Thermal history inversion modelling for five of the above samples show a consistent rapid cooling from 100 ℃ to 30 ℃ between 50-40 Ma, the cooling rate decreased significantly after 40 Ma. Implications of these data, integrated in the context of previously published data for the wider region (e.g. Rohrmann et al. 2012; Haider et al., 2013; Li et al., 2019) will be discussed.</p><p> </p><p><strong>Reference</strong></p><p>Rohrmann, A et al., 2012, Thermochronologic evidence for plateau formation in central Tibet by 45 Ma: Geology, v. 40, p. 187-190.</p><p>Haider, V. L et al., 2013, Cretaceous to Cenozoic evolution of the northern Lhasa Terrane and the Early Paleogene development of peneplains at Nam Co, Tibetan Plateau: Journal of Asian Earth Sciences, v. 70-71, p. 79-98.</p><p>Li, H. A et al., 2019, The formation and expansion of the eastern Proto-Tibetan Plateau: Insights from low-temperature thermochronology: Journal of Asian Earth Sciences, v. 183, 103975.</p>

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