Crustal thickening of the western Tibetan Plateau during the Early Cretaceous: Evidence from adakitic granodiorites, leucogranites, and monzogranites in the Songxi area, western Qiangtang Terrane

Lithos ◽  
2021 ◽  
Vol 390-391 ◽  
pp. 106117
Author(s):  
Qiang Ke ◽  
Tao Hong ◽  
Xing-Wang Xu ◽  
Hao Li ◽  
Xiao-Xue Tong ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Early Cretaceous ◽  
Crustal Thickening ◽  
Western Tibetan Plateau ◽  
Qiangtang Terrane

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 middle Cretaceous (110−94 Ma) evolution of Tangza Basin in the western Tibetan Plateau and implications for initial topographic growth of northern Lhasa

2020 ◽  
Author(s):  
Xu Han ◽  
Jin-Gen Dai ◽  
Jie Lin ◽  
Shi-Ying Xu ◽  
Bo-Rong Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Foreland Basin ◽  
High Elevation ◽  
Alluvial Fan ◽  
Magmatic Arc ◽  
Clastic Rocks ◽  
Western Tibetan Plateau ◽  
Spinel Composition

Reconstruction of Cretaceous geological evolution of Tibetan Plateau growth is critical for assessing the effect of India-Asia collision on the formation of its high elevation. However, Cretaceous topographic evolution and geodynamic mechanism in northern Lhasa remain ambiguous. Here we present results from sedimentology, zircon U-Pb ages, and detrital Cr-spinel composition of the Tangza Formation in the western part of northern Lhasa. Sedimentary lithofacies document that orbitolinid foraminifera−limestone beds were deposited in a shallow-marine setting, while clastic rocks accumulated in an alluvial fan during the middle Cretaceous. Zircon U-Pb ages of interbedded volcanic rocks place a robust constraint on the initiation of clastic rock deposition at ca. 106 Ma. Sandstones are enriched lithic fragments with abundant volcanic grains. U-Pb ages of detrital zircon display a prominent age population at 101−130 Ma with a 120 Ma peak. These data indicate that the clastic rocks were mainly derived from northern Lhasa, including an Early Cretaceous magmatic arc. Sedimentary and provenance characteristics are most consistent with deposition in a local foreland basin. The activation of south-vergent local thrusting may be responsible for loading of the Tangza foreland basin. This thrust faulting may be associated with crustal shortening induced by the continuous convergence of Lhasa and Qiangtang since collision initiated during the Early Cretaceous. The initial uplift of western and central parts of northern Lhasa and eastern Gangdese arc occurred at ca. 106 Ma, while the widespread uplift of northern and central Lhasa probably initiated at ca. 92 Ma. The mid−Late Cretaceous uplift in Lhasa was significantly earlier than the early Cenozoic India-Asia collision.

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.

Crustal Thickening of the South Qiangtang Terrane, Tibetan Plateau: Constraint from Late Cretaceous High-Sr/Y Granitic Rocks

2019 ◽  
Vol 127 (4) ◽  
pp. 457-473 ◽  
Author(s):  
Pei-Yuan Hu ◽  
Qing-Guo Zhai ◽  
Jun Wang ◽  
Yue Tang ◽  
Hai-Tao Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Cretaceous ◽  
Crustal Thickening ◽  
Granitic Rocks ◽  
The South ◽  
Qiangtang Terrane

scholarly journals Timing of the Meso-Tethys Ocean opening: Evidence from Permian sedimentary provenance changes in the South Qiangtang Terrane, Tibetan Plateau

2021 ◽  
Vol 567 ◽  
pp. 110265
Author(s):  
Jian-Jun Fan ◽  
Yaoling Niu ◽  
An-Bo Luo ◽  
Chao-Ming Xie ◽  
Yu-Jie Hao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
The South ◽  
Sedimentary Provenance ◽  
Tethys Ocean ◽  
Qiangtang Terrane

Petrogenesis of the Early Cretaceous granitoids and its mafic enclaves in the Northern Tengchong Terrane, southern margin of the Tibetan Plateau and its tectonic implications

Lithos ◽  
2018 ◽  
Vol 318-319 ◽  
pp. 283-298 ◽  
Author(s):  
Jingyi Zhang ◽  
Touping Peng ◽  
Weiming Fan ◽  
Guochun Zhao ◽  
Xiaohan Dong ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Early Cretaceous ◽  
The Tibetan Plateau ◽  
Mafic Enclaves ◽  
Southern Margin ◽  
Tectonic Implications
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