内蒙古大乌淀石墨矿地质特征与成因探讨

Geological characteristics and genesis of Dawudian graphite deposit in Inner Mongolia

大乌淀石墨矿是近年来在狼山—白云鄂博裂谷带内新发现的超大型石墨矿床,矿体赋存于白云鄂博岩群尖山岩组一段。文章在分析成矿地质背景、矿床地质特征、矿石矿物赋存状态及特征等基础上,对矿床成因进行了探讨,并总结其成矿模式。研究表明:大乌淀石墨矿含矿岩性,主要为各类红柱石石墨片岩;碳质来源为生物有机碳;矿床成因为经区域浅变质后又叠加接触变质的多成因层控矿床。大乌淀石墨矿的成矿作用可概括为原生碳沉积富集,无定型碳热变质转变为石墨核晶;碳硅有机热液交代石墨核晶形成鳞片状石墨的成矿作用过程。

The newly discovered Dawudian huge graphite deposit is located in the Langshan-Baiyun Obo rift zone.The ore body is located in the first member of the Jianshan Formation of the Baiyun Obo Group.Based on the study of metallogenic geological background,geological characteristics of ore deposits,occurrence and characteristics of ore minerals,this paper discusses the genesis of the deposits and summarizes the metallogenic models.The ore is mainly hosted by various andalusite graphite schists and the carbon source is bio-organic carbon.The deposit is in multi-genesis,i.e.the graphite ore was primarily formed during the regional shallow metamorphism and enriched by the following contact replacement.The mineralization process is the primary carbon deposition-thermal metamorphism of amorphous carbon into graphite nuclear crystal and-replacement of graphite nuclear crystal by carbon-silicon hydrothermal fluid and formation of flake-like graphite.