冈瓦纳大陆
奥陶纪
地质学
古生物学
古生代
构造学
边距(机器学习)
显生宙
中国
超大陆
克拉通
考古
构造盆地
新生代
地理
机器学习
计算机科学
作者
Wei Liu,Yuan Liu,Zhaofa Zeng,Baozhong Yang,Lianhong Peng,Di Xu,Yunxu Wei,Yaqing Li,Rob M. Ellam,Sheng Xu
摘要
Numerous K-bentonites from the Ordovician–Silurian (O–S) transition in South China record important information about the geodynamics of volcanic activity in the northern margin of Gondwana. A series of K-bentonite beds have been identified in the Zhoujiaxi Group (Early Silurian) in foreland basins from central Hunan Province, China. They are dominantly composed of illite with minor kaolinite. Volcanogenic minerals include quartz, feldspar, biotite, and lesser apatite and zircon. U–Pb zircon ages from three beds, 442.8 ± 1.8, 442.2 ± 1.9 and 441.6 ± 2.0 Ma are compatible with the age of the O–S global boundary. Geochemical results indicate calc-alkaline felsic magmas derived from continental crust and erupted in a subduction-related collisional environment. Isopach schemes and grain size reveal that the volcanic ashes were sourced from a volcanic event likely with a volcanic explosivity index of 8, and transported 300 – 1000 km away from the palaeo SSE. The volcanism was associated with northwestern subduction of the Zhenghe-Dapu Ocean beneath the southeastern South China Block (SCB) on the northern margin of Gondwana. The Zhenghe-Dapu fault might be a suture zone, implying the consumption of the Zhenghe-Dapu Ocean during collision between the Nanhai terrane and the SCB. This study supports that the Wuyi-Yunkai Orogenic Belt is a collision-type orogen rather than an intraplate belt. Supplementary material: Plots and geochemical data are available at https://doi.org/10.6084/m9.figshare.c.5027096
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