锂同位素示踪斑岩铜矿体系岩浆源区- - 以普朗、羊拉和玉龙铜矿为例

项目名称： 锂同位素示踪斑岩铜矿体系岩浆源区- - 以普朗、羊拉和玉龙铜矿为例

项目编号： No.41303040

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 天文学、地球科学

项目作者： 朱经经

作者单位： 中国科学院地球化学研究所

项目金额： 25万元

中文摘要： 具高氧逸度、富水的岩浆是斑岩铜矿体系铜成矿的必要条件，但目前就其形成机制尚不明确。岩浆体系的氧逸度和含水量显著受其源区特征的制约，因而对斑岩铜矿体系岩浆源区的研究将有助于上述问题的解决。由于传统手段无法有效鉴别俯冲洋壳脱水和部分熔融过程的不同地球化学行为，致使对斑岩铜矿体系岩浆源区的认识存在很大争议。锂同位素是近年来发展迅速的一种非传统稳定同位素，其对流体过程和交代作用十分敏感，可能为解决上述分歧提供了新的思路。本课题拟选择西南"三江"地区具代表性的、形成于不同构造背景和时代的普朗、羊拉和玉龙铜矿的成矿相关岩体为研究对象，在详细的野外地质和前人研究的基础上，将传统地球化学方法与锂同位素研究有机结合，揭示其成矿岩浆源区特征，探讨各构造背景下产出的斑岩铜矿体系的高氧逸度、富水岩浆的形成机制。

中文关键词： 斑岩铜矿；锂同位素；MASH带；俯冲板片；

英文摘要： High oxidation states and water are intuitively key factors for porphyry copper systems, however, the mechanism of such fertile magmas remains uncertainty. The oxygen fugacity and water content are genetically associated with its source region. Apparently, it is necessary to study the magma source of porphyry copper systems so as to find out the mechanism above. It is difficult to distinguish the mantle modified by slab-derived fluid (or island arc) and slab melts by traditional geochemical methods, which makes it debatable for the magma source of porphyry copper systems. Lithium isotope has the potential to trace the two components because it is sensitive in fluid process and metasomatism. The project will focus on the large-scale Pulang, Yangla and Yulong copper deposit in the Sanjiang Domain, which are representative porphyry copper systems formed in island arc, postsubduction, and continental collision environments, respectively. On the basis of detailed field investigation and previous studies, traditional geochemical methods (e.g., major and trace elements, Sr-Nd isotopes, U-Pb geochronology) and Li isotopes will both be used to investigate the magma source of the three deposits, making it possible to discuss the mechanism of magmas with high oxygen fugacity and water.

英文关键词： Porphyry Cu deposit；Lithium isotope；MASH zone；subduction slab；