印度-亚洲大陆碰撞成矿作用主要研究进展

Metallogenesis of the Indo-Asian Collisional Orogen:New Advances

“印度-亚洲大陆主碰撞带成矿作用”973项目（2002-2008年）以青藏高原为研究对象，以构建大陆碰撞成矿理论体系为总体科学目标，经过70多位科技人员历经5年研究，取得了重大研究成果。笔者初步总结了项目在成矿动力学背景、壳／幔深部过程、大陆成矿作用及战略新区预测等方面的研究进展。项目详细再塑了青藏高原碰撞造山过程，创新性提出了碰撞造山三阶段演化模式，即主碰撞聚合（65-41Ma）、晚碰撞转换（40-26Ma）、后碰撞伸展（25-0Ma）三阶段连续演变历程，发现主碰撞期发生岩浆大规模底侵与地壳垂向增生，晚碰撞期出现地幔物质测向流动与幔源钾质岩浆组合，后碰撞期出现岩石圈减薄与伸展岩浆组合。伴随碰撞过程，应力场出现自挤压（压扭）到伸展（张扭）交替更迭变化。综合研究提出了青藏高原碰撞造山地球动力学模式。创新性地提出了大陆碰撞成矿理论体系新框架，包括三大碰撞成矿作用（主碰撞汇聚成矿作用、晚碰撞转换成矿作用和后碰撞伸展成矿作用）、10种重要的成矿系统和12种大陆特色的矿床类型，揭示了大陆碰撞带的区域成矿规律。初步提出了以大陆型斑岩铜矿新理论为代表的5类矿床成矿新模型，揭示了大陆碰撞带金属成矿机制。在系列地质、矿产综合编图和数据库建设基础上，提出了成矿预测新思路和新方法，提交了7处找矿战略新区，并在若干靶区取得找矿突破，探索出一条科研带动勘查突破、勘查提升理论认识的新路。

For the purpose of understanding metallogenesis of continental collisional zones, a five year national program entitled “Metallogenesis of the Indo-Asian Continental Collision Zone （973 project）” was established in 2002, and about 70 researchers from nine institutions of China joined this project. This paper summarizes some new advances in the study of geodynamic setting, deep lithospheric processes and relevant metallogeny of the Tibetan collisional orogenic belt. Three aspects of significant advances have been made in this project, i.e.,①the tectono-magmatic evolution of the collisional orogen,②the collisonal metallogenic theory,③the evaluation of mineral perspectives in the orogen. Based on the studies of the tectono-magmatic activities and relevant lithospheirc process, the authors proposed a three-stage tectonic model for the Tibetan collisonal orogen, from the main collisonal convergence （65-41Ma） through the late collisional tectonic transform （40-26Ma） to the post-collisional extension （25 -0 Ma） processes. Studies show that the main coilisional process resulted in large-scale underplating of syncollisonal mantle-derived magmas and relevant crustal vertical growth in the main collisional zone, and the late collisional process triggered lateral flow of subcontinental lithospheric mantle and created mantle-derived potassic rock suites on the eastern margin of the orogen, whereas the post-collisional extension related to lithos-pheirc mantle thinning produced ultra-potassic and potassic suites and leucogranites along the collisional zone. Each colli-sional period usually underwent a transition from the compressional （transpressional） to the extensional （transtensional） regime in the collisional orogen. Based on studies of the spatial-temporal evolution of tectono-magmatic associations and related mineralization in major metallogenic belts within the orogen, the authors advanced a theory framework for metallogeny of the collisional orogen. It includes three major kinds of metallogenesis, i. e., main-collisional convergent metallogeny, late- collisional transform metallogeny, and post-collisional extensional metallogeny, which produced ten significant ore-forming systems and twelve typical deposit types. Based on the studies of several typical ore deposits in the Tibtean orogen, the authors established five new models for the ore deposits, such as the porphyry Cu deposits unrelated to subduction, the thrust- controlled Pb, Zn, Ag, Cu deposits, the collisional orogenic Au deposits, the REE deposits unrelated to rifting, and the detachment system-controlled Sb, Au deposits. By compilation of a series of geological maps and utilization of mineral resource database, the potential of mineral resources in the orogen has been evaluated, and some perspective areas have been delineated by using new methods proposed in this project.