前寒武纪VMS与BIF铁矿床共生组合研究进展  

Research progress of Precambrian VMS-BIF paragenetic assemblage

作　　者：彭自栋 王长乐[1] 赵刚 朱明田[1] 张连昌[1] 佟小雪 南景博 

机构地区：[1]中国科学院矿产资源研究重点实验室中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学地球科学学院,北京100049 [3]中国有色集团抚顺红透山矿业有限公司,辽宁抚顺113000 [4]中国地质大学地球科学与资源学院,北京100083

出　　处：《矿床地质》2017年第4期905-920,共16页Mineral Deposits

基　　金：国家自然科学基金项目"晚太古代清原绿岩带BIF与VMS矿床的成因联系及沉积环境"(批准号:41572076);"973"项目"华北克拉通前寒武纪重大地质事件与成矿"(批准号:2012CB416601)联合资助

摘　　要：VMS和BIF铁矿作为两种重要的矿床类型,在前寒武纪常常以共生组合方式赋存于古老克拉通内的表壳岩系中,是早期地球构造和环境演化耦合作用的产物。该组合不仅记录了当时特定的构造及大气和海洋环境,而且两者也是全球铜、铁、铅、锌等金属的重要来源,因此,开展VMS与BIF共生组合的研究具有重大科学价值和经济意义。前人研究表明,前寒武纪VMS与BIF集中出现于~2.7 Ga和~1.9 Ga,与同时期地幔柱活动和地壳增生的高峰相对应,两者共生时BIF通常产出于VMS外围或上盘,但在矿体空间展布上具有此消彼长的关系;研究还认为,前寒武纪地幔柱活动诱发的海底扩张、海底和地表强烈的火山活动形成的多重热液系统,可同时为VMS和BIF提供物质来源,海水的硫逸度、氧逸度及大气的氧含量是影响VMS与BIF空间分布及VMS硫同位素组成的重要因素。目前,VMS与BIF共生组合研究取得了较大进展,但仍存在一些问题:缺乏典型共生实例的精细解剖,已有共生模型缺乏详细的矿床成因机制研究支撑,对两者共生组合产出的构造背景和古海洋环境仍存在不同认识。华北克拉通的清原和五台新太古代绿岩带发育有较大规模的VMS与BIF铁矿共生现象,对其开展详细研究工作将为解决上述问题提供借鉴。VMS and BIF are two kinds of important deposit types,regarded as syngenetic and stratabound deposits within the supracrustal rocks of old craton in Precambrian,which were formed as a result of the coupling of tectonic movement and environmental evolution of the early Earth. Previous researches indicated that the mantle plume activity and crustal growth at - 2. 7 Ga and - 1. 9 Ga culminated the VMS-BIF paragenetic assemblage in Precambrian,and when BIF and VMS formed synchronously they usually occurred at the same stratigraphic horizon with BIF in the immediate vicinity of or slightly higher than the VMS. These studies also suggested that mantle plume events in Precambrian led to the spreading of midocean ridges and volcanism,which happened both on the ocean floor and at the earth surface,both processes thus having contributed to the forming of multiple hydrothermal systems; meanwhile,those systems provided ore-forming materials for VMS and BIF. Furthermore,the sulfur fugacity of the hydrosphere and the oxygen content of the ocean and atmosphere seem to have been key factors influencing the distribution of VMS and BIF as well as the sulfur isotopic compositions of VMS. Great progress has been made to figure out this intriguing and not fully answered question about the co-existence of VMS and BIF. However,there are still some problems,for example,there is no sufficient detailed study of living cases,the existing paragenetic model requires more study on genetic mechanism,and the geological setting and hydrosphere conditions for the formation of VMS and BIF remain ambiguous. Specifically, both the VMS and BIF in the Neoarchean Qingyuan and Wutai greenstone belt of the North China Craton were formed synchronously as shown by recent high-precision geochronology work; hence,a detailed study of those deposits may be a fruitful approach to solving the above questions.

关 键 词：地质学 火山成因块状硫化物矿床 条带状铁建造 成因机制 

分 类 号：P618.31[天文地球—矿床学]