阿尔金山南缘长沙沟镁铁-超镁铁质层状杂岩体（或岩体群）的岩石成因机制及其对成矿的制约研究

This project would research the igneous sequences and the characteristics of mineralogy, petrology, lithogeochemistry and isotope geochemistry of these four layered mafic-ultramefic intrusions discovered recently in Changshagou areas, Southern Altyn Tagh, and their formation ages. We could illuminate their source region propoties, temperature and pressure conditions, primary and parential magma components, fractional crystallization, magmatic mixing, crustal contamination and magmatism event sequences; and elucidate the petrogenesis and metallogenesis for the V-Ti-magnetite deposit in Changshagou layered intrusions. In addition, we would study the potential relationships on the tectonic evolution of southern Altyn Tagh and formation mechanism between the ultra-high press metamorphic rocks, ophiolites, granitoid rocks in southern Altyn Tagh and these Changshagou layred mafic-ultra mafic intrusions, and try to make out the relation of connection and conversion in the period of Paleozoic between different geodynamics systems in the southern Altyn Tagh.

通过对阿尔金山南缘长沙沟地区新发现的四个镁铁-超镁铁质层状杂岩体(或岩体群)的火成层序、矿物学、岩石学、岩石及同位素地球化学、同位素年代学的研究，从镁铁-超镁铁岩的地幔源区组成特征、温-压条件、原生岩浆和母岩浆组成及其结晶分异、岩浆混合、地壳混染,以及岩浆事件序列等方面，综合研究此四个层状杂岩体(或岩体群)的岩石成因-岩浆作用过程及相互联系，阐明岩体的成因机制和其中新发现的V-Ti-磁铁矿床的成因机制，尝试研究南阿尔金山地区与这些镁铁-超镁铁质层状岩体共存的大陆深俯冲超高压变质岩、蛇绿岩、相关的花岗岩等在南阿尔金山(古生代?)构造演化序列及内在机制上可能的关联性和该地区不同地球动力学体制的相互衔接-转换关系。

通过对对长沙沟层状杂岩体（群）的岩浆事件序列、岩石成因-岩浆作用过程、相互间联系、长清铁矿V-Ti-Fe磁铁矿富集机制、长沙沟层状岩体群与南阿尔金地区蛇绿岩、超高压变质岩、花岗岩在南阿尔金山构造演化序列及内在动力学机制上的关联性等研究，认为长沙沟层状岩体群为南阿尔金山后碰撞裂谷伸展背景下，不同地幔源区近同时（~465Ma）分别发生部分熔融作用就位于阿南断裂带不同部位所形成的两类层状杂岩体，并与同期（约469~445Ma）大规模的中酸性岩浆构成南阿金山早古生代中期“双峰式”岩浆活动。其中清水泉南、长沙沟中段、黄土泉层状岩体构成同源岩浆演化系列，其源区为上涌的热的软流圈地幔，并可能存在与岩石圈地幔的相互作用；清水泉北岩体源区为受前期洋壳俯冲脱水交代的岩石圈地幔；研究讨论了四个层状岩体Cu-Ni-PGE含矿性，认为黄土泉镁铁-超镁铁质岩体具有良好的Cu-Ni硫化物成矿潜力和找矿前景。研究成果对于完整认识南阿金山地质构造演化、理解壳幔相互作用等具有重要的科学意义，对长沙沟地区地质找矿工作具有理论指导意义。