EGU21-11976, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Tectonic evolution of the Paleo-Tethys Ocean in Southwest Guangxi: evidence from acidic magmatic rocks in the Pingxiang area, SW China

Wenmin Huang1, Xijun Liu1,2, Zhenglin Li1, Bing Zhao1, and Yiying Han1
Wenmin Huang et al.
  • 1Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,College of Earth Sciences, Guilin University of Technology, Guilin, 541004, China (
  • 2Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resource Guilin University of Technology, Guilin 541004,China (

Early Mesozoic development of Southeast Asia involved oceanic subduction, closure, accretion and collision of discrete terranes rifted from Gondwana. South China, as an important continental terrane, is bound to the north by the Qinling-Dabie collisional orogenic belt, to the south by the Indochina Block, and to the east by the Pacific Plate. The role of continental collision and subduction during the Early Mesozoic development of South China has sparked the interest of geologists worldwide and stimulated considerable research. The Triassic tectonic history of the southwestern South China Block is marked by the Indosinian orogeny that records amalgamation of the Indochina and South China blocks during the late Permian to Triassic as a result of closure of the eastern branch of the Paleo-Tethys Ocean. In South China, there is widespread granitic magmatism, metamorphism and deformation. The closure of eastern Paleo-Tethys Ocean and subsequent collision between the South China block and Indochina Block has caused the collision zone metamorphism and formation of granites during the Permo-Triassic, with the Song Ma fault zone as the collision boundary. The Indosinian magmatism in the Pingxiang region was the magmatic products in this period. We report the new results of bulk-rock major and trace element, Nd, Hf isotopic compositions and zircon U–Pb dating of granites and rhyolites in the Pingxiang region in Guangxi Province, Southwest China, to decipher their petrogenesis and tectonic settings. The granites and rhyolitics in the Pingxiang area have low Mg# values (11.1–36.7), low Nb/Ta ratios (9.26–13.74) exhibiting a both affinity from S-type to I-type granaite. The isotopic features of these rocks show negative εHf(t) with the values ranging from -9.89 to -6.09, negative εNd(t) values ranging from -12.89 to -12.02 and T2DM values of 1.8–3.3 Ga, suggesting that the Pingxiang granites and rhyolites was derived from partial melting of paleoproterozoic crust rocks. The granites yielded 206Pb/238U ages ranging from 243 to 241 Ma, and the rhyolites yielded 206Pb/238U ages ranging from 247 to 245 Ma, which are both within the age range of the subduction to collision. Combine the regional geology, we suggest these granitoids and rhyolites were formed by the partial melting of crustal rocks during a transition from subduction to post-collisional environment with closure of Paleo-Tethys Ocean between the South China block and Indochina Block.

This study was financially supported by Guangxi Natural Science Foundation for Distinguished Young Scholars (2018GXNSFFA281009) and the Fifth Bagui Scholar Innovation Project of Guangxi Province (to XU Ji-feng).

How to cite: Huang, W., Liu, X., Li, Z., Zhao, B., and Han, Y.: Tectonic evolution of the Paleo-Tethys Ocean in Southwest Guangxi: evidence from acidic magmatic rocks in the Pingxiang area, SW China, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11976,, 2021.