四川旺苍大河坝晶质石墨矿地质特征与成因

Geological characteristics and genesis of Dahaba crystalline graphite deposit in Wangcang,Sichuan

大河坝晶质石墨矿位于旺苍—南江石墨矿带中部,是川北地区新发现的超大型晶质石墨矿。矿体赋存于中—新元古界火地垭群麻窝子组,赋矿岩性主要为夹在白云质大理岩中的石墨片岩,具明显层位特征。矿体延伸稳定,主矿体延伸长度达3 km,平均厚度为23 m,平均品位为15%。通过原岩恢复,表明矿体原岩为沉积于弧后浅海的含炭质黏土细—粉砂岩,原岩沉积于贫氧—缺氧的还原环境,石墨炭质来源为有机质。矿床成因属沉积-混合变质型,变质作用为区域变质叠加热接触变质。

Daheba crystalline graphite deposit is located in the middle of the Wangcang-Nanjiang graphite ore belt,which is a newly discovered super-large crystalline graphite deposit in North Sichuan.The orebody is hosted in the Mawozi Formation of the Huodiya Group in the Meso-New Proterozoic.The ore-hosting lithology is mainly graphite schist sandwiched in dolomitic marble,with obvious layer characteristics.The extension of the orebody is stable,the extension length of the main orebody is 3 km,the average thickness is 23 m,and the average grade is 15%.The recovery of the original rock indicates that the original rock of the orebody is the fine-siltstone of carbonaceous clay deposited in the shallow back-arc sea,and the original rock is deposited in the oxygen-poor-anoxic reducing environment.The source of graphite and carbon is organic matter.The genesis of the deposit belongs to sedimentary-mixed metamorphism type,and the metamorphism is regional metamorphism and thermal contact metamorphism.