西昆仑塔什库尔干古元古代条带状铁矿地质特征及成矿作用研究

The Tashikuergan iron ore belt in West Kunlun of Xinjiang province have been recently discovered as one of large-scale regional metallogenic belts. Research from previous workers indicate that major iron deposits located in this belt occur in meta-volcanic sedimentary rocks of Paleoproterozic Bulunkuole Group. Geological characteristics are similar to Precambrian BIF-type iron deposits to some extent but have been obscured due to various degrees of superposed reformation processes after primary deposition, resulting in much debate on their concrete type and complex genesis. Thus, we are aiming at giving a detailed study on Paleoproterozoic meta-volcanic sedimentary rocks in typical iron areas, including aspects of well constraining metallogenic and diagenetic ages, elaborating evolution from volcanic sedimentary rocks to iron formations succession, confirming accurate types of iron deposits in Tashikuergan iron ore belt. Further efforts should be taken to obtain geochemistry of iron deposits, corresponding sedimentary environment and the origin of iron formations, and to further deduce metallogenic mechanism using element, isotope and mineral micro region analysis. Major iron deposits forming about coincide with Great Oxdation Event(GOE)(2.45~2.2Ga) might provide geological records as implications for GOE which could have affected migration and precipitation of metallogenic elements. Combined with comprehensive analysis of above-mentioned geochemical characteristics and regional geological information, the relationship between metallogenic systems and evolution of Paleoproterozoic geology and environment in West Kunlun, the summary of metallogenic regularity, the construction of metallogenic model for iron deposits could be ultimately revealed.

新疆西昆仑塔什库尔干铁矿带是我国新近发现具有大型规模的区域成矿带之一。前期研究表明，该矿带的主要铁矿赋存于古元古代布伦阔勒群火山-沉积变质岩系中，矿床地质特征反映铁矿主体具前寒武纪条带状（BIF）铁矿的一般特征，但大多数矿区遭受了不同程度的后期改造叠加作用。本申请通过对典型铁矿区古元古代火山-沉积变质岩系的详细研究，精确限定成岩成矿时代，建立精细的火山沉积-铁建造演化序列，确定塔什库尔干铁矿带矿床类型；运用元素-同位素、矿物微区分析等方法，研究条带状铁矿的地球化学组成和沉积环境、成矿物质来源，揭示塔什库尔干条带状铁矿的形成过程及成矿机理；识别因古元古代大氧化事件导致环境剧变的地质记录和事件序列，探讨环境变化过程中成矿元素迁移和沉淀机理。通过矿床地质和区域地质资料的综合分析，揭示西昆仑古元古代地质-环境演化与条带状铁矿大规模成矿之间的关系，总结区域铁矿成矿规律，建立铁矿成矿模式。

新疆西昆仑塔什库尔干铁矿带是我国南疆地区新近发现的大型磁铁成矿带。经区域地质、典型矿床和成矿作用地球化学综合研究，表明该矿带主要铁矿（赞坎、莫喀尔等）赋存于古元古代布伦阔勒群火山-沉积变质岩系中，矿床地质特征反映铁矿主体具前寒武纪条带状（BIF）铁矿的一般特征，但赞坎矿区遭受了后期改造叠加，局部形成富矿；同时研究表明区域上还发育一套早寒武世形成的沉积变质型硫酸盐-磁铁矿床（如喀来子、叶里克等）。通过精确成岩成矿时代，建立了区域火山沉积-铁建造演化序列，确定了塔什库尔干地区存在2类铁矿床；运用元素-同位素、矿物微区分析等方法，研究了铁矿的沉积环境、成矿物质来源，揭示了塔什库尔干条带状铁矿的形成过程及成矿机理；识别出区域地质-环境演化与条带状铁矿大规模成矿之间的关系，建立了2类铁矿成矿模式，这对于指导区域成矿规律的总结及开展进一步的找矿预测工作均具有重大意义。