1. Ca. 110 Ma adakite-like magmatism along the Bangong–Nujiang suture zone: Implications for crustal thickening and early uplift in the central Tibetan Plateau.
- Author
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Wang, Wei, Zhai, Qing-guo, Hu, Pei-yuan, Tang, Yue, Wang, Hai-tao, Zhu, Zhi-cai, Wu, Hao, and Huang, Zhi-qiang
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SUTURE zones (Structural geology) , *MAGMATISM , *PLATEAUS , *ADAKITE , *YTTERBIUM , *AMPHIBOLITES , *MAGMAS , *ZIRCON - Abstract
The suggested Early Cretaceous timing of early formation of the Tibetan Plateau remains controversial. This study investigates this uncertainty by examining newly identified Early Cretaceous adakite-like magmatic rocks in the Rutog and Nyima areas of the northern–central Tibetan Plateau. Zircon U Pb dating indicates that these rocks formed at ca. 110 Ma and have negative to positive zircon ε Hf (t) values. They contain high concentrations of Sr and have high Sr/Y values, but contain low concentrations of Y and Yb and have low (La/Yb) N , suggesting they have an adakite affinity. They also have ε Nd (t) values that range from −4.5 to +1.3. These geochemical and isotopic data indicate that the adakite-like rocks probably formed from magmas generated by the partial melting of garnet-bearing amphibolite within a thickened region of juvenile and ancient crustal material. This magmatism also most likely occurred during the Lhasa–Qiangtang collisional event. Crustal thicknesses along the Bangong–Nujiang suture zone (BNSZ) were > 40 km in places at ca. 110 Ma, and most likely had a significant impact on the initial uplift of the Tibetan Plateau. In summary, the Early Cretaceous adakite-like magmatic rocks in the Rutog and Nyima areas suggest that the Tibetan Plateau started to form during the Early Cretaceous. • Early Cretaceous adakite-like rocks occur in the north-central Tibet. • Adakite-like rocks were derived from the thickened crust. • The Lhasa–Qiangtang collision happened before ca. 110 Ma. • The significant crustal thickening led to the early uplift in the Early Cretaceous. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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