巴基斯坦基性-超基性岩铬尖晶石矿物化学及铬铁矿找矿潜力分析

摘要

基性-超基性岩体广泛分布于巴基斯坦北部印度河缝合带和中南部碰撞带，发育有与蛇绿岩有关的铬铁矿床，多数岩体工作程度偏低。铬尖晶石是指示岩石成因和构造环境的有效标志。铬尖晶石矿物化学研究表明其岩体可划分为3类，其中尚拉-明戈拉、德尔盖、瓦齐里斯坦、穆斯林巴赫和贝拉岩体中造矿铬尖晶石的成分显示富Cr、贫Al、低Ti特征，副矿物铬尖晶石的Cr#变化范围指示其构造背景为大洋中脊向俯冲带之上的过渡环境，与我国罗布莎含矿岩体非常相似。通过对比分析典型豆荚状铬铁矿成矿地质特征和成矿规律，认为贝拉、穆斯林巴赫等岩体成矿条件有利，具较大找矿潜力。%The mafic-ultramafic complexes are mainly distributed in the Indus suture zone in the north,collision zone in the south-central part of Pakistan.Chromite deposits related to ophiolite occur within these complexes, but most of them are low-degree studied.Picotite is a useful indicator for the petrogenesis and tectonic environment.The study of min-eral chemistry of chrome spinel indicate that these complexes can be divided into three kinds,the segregated chromites from Shangla-Dargai,Waziristan,Muslimbagh,and Bela complexes shows Cr-rich, Al-poor and low TiO2, range of Cr# from picotite appear to indicate a transitional tectonic settings from MOR to SSZ.These characteristics are similar to the Luobusha chromite in China. Through the comparative analysis of the geological conditions and metallogenic regulari-ties of the typical podiform chromite deposits, we hold that there is great potential for the prospecting of chromite depos-it in the Bela, Muslimbagh ophiolite because of the favorable metallogenic conditions.