Crustal melting above a mantle plume: Insights from the Permian Tarim Large Igneous Province, NW China

• Published in: Lithos
• Main Authors: Liu, Hai-Quan, Xu, Yi-Gang, Zhong, Yu-Ting, Luo, Zhen-Yu, Mundil, Roland, Riley, Teal R., Zhang, Le, Xie, Wei
• Format: Report
• Language: English
• Published: ELSEVIER SCIENCE BV 2019
• Subjects: Geochemistry & Geophysics; Mineralogy; ZIRCON U-PB; LARGE-VOLUME; ANTARCTIC PENINSULA; HIGH-TEMPERATURE; LITHOSPHERE INTERACTION; RHYOLITIC VOLCANISM; YELLOWSTONE HOTSPOT; CALDERA COMPLEXES; SILICIC VOLCANISM; ISOTOPIC EVIDENCE; Antarctic; Antarctic Peninsula; Patagonia; Antarc*
• Online Access: http://ir.gig.ac.cn/handle/344008/52653; https://doi.org/10.1016/j.lithos.2018.12.031

Low Nb-Ta rhyolites from the Permian Tarim Large Igneous Province (LIP) represent the melting products of continental crust above a mantle plume. Zircon U-Pb dating reveals that the Kuchehe and Dawanqi rhyolites were erupted at 292.6 +/- 0.5 Ma and 274 +/- 2 Ma respectively. Both rhyolite groups are characterized by pronounced negative Nb-Ta anomalies, crust-like trace element ratios and negative epsilon(Nd-Hf)(t) values, consistent with a crustal origin. Newly acquired data, combined with available data in the literature, clearly show that there is an increasing trend of zircon saturation temperature (T-Zr) from 794 to 827 degrees C to 886-936 degrees C for the early to middle stage (293-287 Ma), followed by a decreasing T-Zr of 803-908 degrees C for the late stage (287-274 Ma) of the Tarim magmatism. The temporal changes in T-Zr for the Tarim rhyolites are interpreted to reflect the crustal melting behavior above a mantle plume, such that fusible materials in the crust melt at an earlier stage and refractory materials melt at a later stage. The gradual decrease in T-Zr, towards the final stage of the Tarim rhyolitic magmatism, reflects the gradual 'decay' of thermal input from mantle plume to the lithosphere in the region. This thermal model is also applicable to describe the crustal melting behavior in the Chon Aike silicic LIP of Patagonia and the Snake River Plateau-Yellowstone Plateau volcanic provinces. (C) 2018 Elsevier B.V. All rights reserved.