摘要
双峰式火山岩不仅是火山成因块状硫化物矿床中最常见的含矿岩石组合 ,而且也是研究其古成矿地质背景和成矿作用的主要依据之一。笔者收集了我国以及世界一些著名火山成因块状硫化物矿床和矿带的含矿建造资料 ,其中包括含矿建造的岩石组合、形成时代和层序、火山岩的岩石组合和岩石化学、产出的大地构造环境等等。整理结果表明 ,双峰式火山岩是火山成因块状硫化物矿床的最佳含矿岩石组合 ;它们主要产于各个时期的造山带中 ,形成于以会聚板块边界为大背景的局部引张阶段 ;这种构造背景造就了规模巨大的有利成矿的钙碱性长英质火山岩类 ,产生了有利成矿组分浓集的巨大热液循环系统及适宜的 (海水深度和封闭条件良好的 )含矿流体集积的沉陷盆地 (裂谷 ) ,从而为成群成带的VHMS型矿床的形成提供了有利的地质环境。
Bimodal volcanic rocks are not only the most common host rock association of volcanic_hosted massive sulfide (VHMS) deposits, but also serve as the main grounds for studying the ore_forming geological settings and ore_forming processes of these deposits. The author has collected the data on host rock formations of some well_known volcanogenic massive sulfide deposits and belts both in China and abroad, which include rock associations, time and successions of host rock formations, and rock associations, chemical composition, and tectonic settings of volcanics. Studies show that bimodal volcanics constitute the most favorable host rock association for volcanogenic massive sulfide deposits. They mainly occur in orogenic belts of various geological times and are formed during extension periods against the background of convergent plate margins. Such tectonic settings contain a large volume of calc_alkaline acidic volcanics associated with mineralizations, form large_scale ore_forming hydrothermal convective circulations and subsidence (rift) basins where the seawater depth and closed condition are suitable for precipitation of ore fluids, and provide favorable geological prerequisites for the formation of VHMS type deposits distributed in groups and belts.
出处
《矿床地质》
CAS
CSCD
北大核心
2001年第4期331-338,共8页
Mineral Deposits
