西藏狮泉河蛇绿岩的成因、年代序列及其构造演化

狮泉河蛇绿岩是西藏西部层序完整、出露面积较大的关键蛇绿岩之一，它形成到侵位的年代学序列、岩石成因和构造演化，是正确认识中特提斯洋格局和构造演化的关键问题。由于研究程度较低，对于其成因，存在有弧前盆地、多岛弧盆系统到班公湖蛇绿岩的推覆体等多种认识。拟精选狮泉河蛇绿岩1-3条典型剖面，通过野外地质考察，岩相学和矿物学，全岩地球化学、矿物原位微区LA-ICP-MS微量和电子探针主量分析，Sr-Nd-Pb-Hf同位素示踪，揭示狮泉河蛇绿岩的构造环境和岩石成因；开展地幔橄榄岩Re-Os定年，堆晶岩、岩墙、熔岩以及斜长花岗岩锆石U-Pb定年、侵位成因变质晕和断层岩Ar-Ar定年，建立蛇绿岩演化的年代学序列；通过区域对比，恢复其构造演化史，为重建整个中特提斯洋构造格局和演化提供依据。

The Shiquanhe ophiolite has a well-exposed, complete sequence in western Tibet. Its chronology from formation to emplacement and the tectonic evolution are critical to understanding the tectonic framework and evolution of the Bangong-Nujiang Meso-Tethys. Up to now, diverse opinions exist about the petrogenesis of the Shiquanhe ophiolite, ranging from for-arc basin, archipelagic arc-basin system, or thrust slice from the Bangong lake ophiolite. In this study, we plan to focus on 1-3 typical ophiolite sections, in an attempt to reveal its tectonic setting, petrogenesis and chronology. We will perform field survey, petrographical and mineralogical observations as well as comprehensive studies on geochemistry and isotope chronology, including whole-rock geochemistry, in-situ LA-ICP-MS mineral trace-element analysis and EPMA major-element analysis, Sr-Nd-Pb-Hf isotope analysis, Re-Os dating, zircon U-Pb dating, and Ar-Ar dating. We will discuss its tectonic setting, and establish the tectonic evolution model of the Shiquanhe ophiolite.