Permian-Triassic Magmatism in the Qin-Fang Tectonic Belt， SW China: New Insights into Tectonic Evolution of the Eastern Palaeo-Tethys

作者：Yun Zhou; Yongshan Zhao; Yongfeng Cai; Qiaofan Hu; Ce Wang

来源：Journal of Earth Science, 2020, 1-59.

• Palaeo-Tethyan ocean
• zircon U-Pb
• granite
• Permian-Triassic
• Qin-Fang tectonic belt

The granites of ambiguous geodynamic mechanism in the Qin-Fang tectonic belt (SW China) were studied in detail based on petrological， element geochemical， zircon U-Pb geochronological， and Hf isotopic data. LA-ICPMS U-Pb analyses on zircon yield ages of 248-245 Ma for the granites from the Qin-Fang tectonic belt. The geochemical data show that they are high-K， calc-alkaline， and peraluminous series. Their ε_(Hf)(t) values are from -14.01 to -7.75 with two-stage model ages of 1.74–1.43 Ga. These data， integrated with low Al_(2)O_(3)/TiO_(2)， Rb/Sr， Rb/Ba， and (Na_(2)O + K_(2)O)/(FeO~(T) + MgO + TiO_(2)) ratios， and high CaO/Na_(2)O ratios for the granite， suggest an origin from psammite source which was contaminated by mantle-derived components. These observations， in combination with the age data and stratigraphic records in the Jinshajiang， Ailaoshan， and Hainan Island areas suggest that the granites were formed in a post-collision tectonic setting. The Qin-Fang tectonic belt was likely a branched ocean basin of the eastern Palaeo-Tethys.

• 单位
  中山大学; 桂林理工大学