西藏中部中仓地区玄武岩锆石U-Pb 年龄与岩石 地球化学特征:对狮泉河－纳木错弧后洋盆演化的 制约

作者：Wu Hao; Lin Zhaoxu; Jiang Ziqi; Wang Chonghao; Zheng Xin; Yang Rui

来源：Geological Bulletin of China, 2022, 41(10): 1728-1739.

DOI：10.12097/j.issn.1671-2552.2022.10.003

• back-arc extension
• basalt
• Central Tibet
• Early Cretaceous
• geological survey engineering
• Shiquan River-Namu Co mélange zone

Tectonic attribute and evolution history of Shiquan River-Namu Co mélange zone have been controversial for a long time.This paper deals with the petrology, geochronology, and geochemistry of the basalts from the Zhongcang ophiolite mélange, in order to reveal its formation age, petrogenesis and tectonic significance.LA-ICP-MS zircon U-Pb age of Zhongcang basalt is 115.7±2.0 Ma, which is consistent with the formation age of gabbro in the region.The Zhongcang basalts have a relatively flat REE distribution curve, similar to the mid-ocean ridge basalt(MORB).Furthermore, these samples show Th enrichment and Nb, Ta depletion.It is proposed that the Zhongcang basalts were derived by partial melting of the spinel peridotite mantle, which was modified by subduction sediments, in the back-arc basin spreading center.Combined with the study of the regional gabbros, our research favors that the Shiquan River-Namu Co mélange zone represents the remnant of a Mesozoic back-arc basin, which was produced by the back-arc rifting in response to the southward oceanic subduction of Bangong-Nujiang Tethyan Ocean. ? 2022 China Geological Survey.

• 单位
  桂林理工大学