Post-collisional adakitic biotite plagiogranites from Guangtoushan pluton (Mianxian, central China): Petrogenesis and tectonic implication

Springer Science and Business Media LLC - Tập 1 - Trang 299-303 - 2007
Jiangfeng Qin1, Shaocong Lai1, Yongfei Li1
1State Key Laboratory of Continental Dynamics/Department of Geology, Northwest University, Xi’an, China

Tóm tắt

The post-collisional Guangtoushan pluton intruded into the Mianlue suture, Central China. Geochemically, the Guangtoushan biotite plagiogranites show many close compositional similarities to high-silica adakites from the supra-subduction zone setting, but tend to have a higher concentration of K2O (3.22%–3.84%). Chondrite-normalized rare earth element patterns are characterized by high ratios of (La/Yb)N, concave-upward shapes of the heavy rare earth element (HREE), and a lack of significant Eu anomalies. In conjunction with high abundances of Ba and Sr, as well as low abundances of Y and HREE, these patterns suggest a feldspar-poor, garnet±amohibole-rich fractionation mineral assemblage. Coupled with previous studies, we suggest that the Guangtoushan biotite plagiogranites were likely to be caused by subducting slab break-off during the late orogenic stage in the West Qinling orogenic belt.

Tài liệu tham khảo

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