新疆东天山小白石头钨（钼）矿成矿作用研究

The East Tianshan of Xinjiang is characterized by a number of Late Paleozoic magmatic Cu-Ni deposits, porphyry copper deposits, and submarine volcanic rocks-related iron deposits. However, in recent years, the Triassic large and super-large size skarn tungsten and porphyry molybdenum deposits were discovered, and the intrinsic link and major controlling factor between tungsten and molybdenum deposits is an important scientific concerns which need to understand. The Xiaobaishitou W-(Mo) deposit, a newly discovered medium-sized deposit, is the best place for studying the mineralization relationship between tungsten and molybdenum. The Xiaobaishitou W-(Mo) deposit is chosen as a major study object in this study. On the basis of a systematic study of deposit geology and an anatomy of the Xiaobaishitou W-(Mo) deposit, the author focuses on the intrusive rocks, skarn, large quartz veins, mineralization distribution, mineral assemblages, wall rock alteration and enrichment process of ore-forming elements. The research on mineralogy, geochemistry, fluid inclusions, isotop geoemistry and geochronology is to discuss the mineralization relationship between skarn type and large quartz vein type, and the controlling factors tungsten and molybdenum mineralization, metallogenic materials, nature, origin and evolution of ore-forming fluids, magmatism, metallogenic epoch, the enrichment process of tungsten and molybdenum. The purpose of the study is to investigate the mineralization of tungsten and molybdenum, and to establish reasonable metallogenic model, and summing up the metallogenic regularity and ore controlling factors. This study not only enriches the metallogenic theory in Central Asian Orogenic Belt but also provides a theoretical basis of prospecting exploration for tungsten and molybdenum deposits in the East Tianshan.

新疆东天山以发育晚古生代岩浆型铜镍矿、斑岩型铜矿和与海相火山作用有关的铁矿为特色，但近年来发现了三叠纪大型、超大型矽卡岩型钨矿和斑岩型钼矿，钨矿和钼矿之间的内在联系和主要控制因素是一个有待查明的重要科学问题。小白石头是近年来有找矿新发现的中型钨（钼）矿，是研究钨和钼成矿作用内在联系的理想场所。本项目以小白石头钨（钼）矿床作为重点解剖对象，以系统的矿床地质学研究为基础，重点开展侵入岩、矽卡岩、石英大脉、矿化、矿物组合、围岩蚀变、成矿元素富集规律研究；通过矿物学、岩石地球化学、流体包裹体、同位素和年代学研究，查明矽卡岩型和石英大脉型矿化关系，钨和钼矿化控制因素，探讨流体的性质、来源、演化，成岩和成矿时代，解析钨、钼的聚集沉淀过程。目的在于探讨钨和钼成矿作用，建立合理的成矿模型，总结成矿规律和控矿因素。本项研究不仅丰富了中亚造山带成矿理论，而且为东天山钨钼矿找矿勘查工作提供理论基础。

新疆东天山发现了三叠纪大型、超大型矽卡岩型钨矿和斑岩型钼矿，钨和钼矿之间内在联系是重要科学问题。小白石头钨（钼）矿中圈定出钨矿体、钼矿体和钨钼矿体，是研究钨和钼成矿作用内在联系的最佳场所。本项目以小白石头钨（钼）矿作为重点解剖对象，开展了矿床地质特征、不同期次侵入岩、矽卡岩、石英大脉、矿化、矿物学、成矿物质来源、成矿流体、成矿元素富集规律、成矿时代及成矿机制研究。建立了矿区侵入岩年龄谱系，岩浆活动出现在新元古代（908Ma）、泥盆纪（407～412Ma）、石炭纪（325Ma）和三叠纪（246～252Ma），后三者对应的构造环境分别为岛弧、陆缘弧和板内伸展环境。获得辉钼矿Re–Os年龄和白云母40Ar–39Ar坪年龄分别为245～251 Ma和248 Ma，表明矿床形成于早三叠世，与黑云母花岗岩热液活动有关。黑云母花岗岩的岩浆起源于幔源和壳源物质混合，后期同化混染过程中有更多地壳物质加入。矿化赋存于黑云母花岗岩与中元古界卡碳酸盐岩接触带的矽卡岩中，矿床形成经历四个成矿阶段，最早为早期矽卡岩阶段（I），钨矿化形成于退化蚀变阶段（II）和石英硫化物阶段（III），钼矿化形成于III阶段，最晚为方解石阶段（IV）。从早阶段到晚阶段成矿温度和盐度逐渐降低，流体沸腾作用和氧逸度变化导致了白钨矿和辉钼矿大量沉淀。H、O、C、S、He、Ar同位素组成表明，I阶段流体源于岩浆水，并在岩浆-热液活动后期经历了强烈分馏作用；II阶段流体来自岩浆水，有大气降水加入；III阶段流体为岩浆水和大气降水混合；IV阶段以大气降水为主。成矿物质主要来源于壳源花岗岩，混合有深源物质。提出钨钼共生关键为壳幔物质共同参与、充分的岩浆演化和开放的成矿环境。通过综合对比研究，建立了区域和矿床成矿模型。小白石头钨成矿机制研究，丰富了中亚造山带三叠纪成矿理论，总结成矿规律，建立矿床模型为新疆钨钼矿找矿勘查提供理论基础。