摘要
研究区地处扬子地台西缘 ,西与松潘甘孜地槽褶皱带以窄小的古火山岩带相隔。在观音崖组、灯影组以及康定群变质杂岩中广泛发育有辉绿岩脉、岩墙。辉绿岩受断裂控制 ,岩脉边部具碎裂结构、糜棱结构、块状构造。岩石蚀变强 ,除少量的斜长石、辉石原生矿物残余外 ,主要由钠长石、角闪石、绿泥石、绿帘石和方解石等变质矿物组成。按岩石化学成分 ,辉绿岩属拉斑系列、钾质类型 ,但按辉石成分 ,也有碱性系列。岩石稀土元素、微量元素表明 ,辉绿岩与茶铺子细碧岩属同源岩浆产物 ,相当于板块碰撞后的次火山活动产物 ,岩浆房深度约为 2 5km。辉绿岩的Au背景值高 ,是Au、Cu矿的矿源层。辉绿岩赋存的断裂是导矿构造 ,辉绿岩浆活动使康定群中的Au活化并随岩浆迁移 ,成矿热液沿断裂上升被辉绿岩阻挡在下盘围岩中成矿。辉绿岩是该区良好的找矿标志。
The studied area locates at Tianwan area, Shimian county,Sichuan Province and between the western margim of the Yangtze Platform and the Songfan-Ganzi folded system separated by a narrow volcanic rock belt, where diabase dikes and veins controlled by fault system are widespread in the Sinian Guanyinya formation, Dengying formation and Archean-Proterozoic metamorphic complex (Kangding Group). Cataclactic and mylonitic texture as well as massive structure can be found in the rim of diabase dikes and veins which have been strongly altered and mainly consist of albite, amphibole, chlorite, epidote and calcite with a little residual plagioclase and pyroxene. According to the petrochemical data, diabases belongs to potassium type tholeiitic series. REE and trace element characteristics shows that diabase has the same source with the Chapuzi spilite in the studied area, being resulted from a 25 km deep magma chamber through post-collision sub-volcanism. With high gold abundance, the diabase should be the source bed of Au-Cu deposits and gold remarks for prospecting of deposits in the studied area, because intrusion of the diabase along faults resulted to remobilization of gold from the Archean-Proterozoic Kangding metamorphic complex, when the ore-forming fluids drifted along the rupture and was obstructed by the diabase, gold mineralization happened in the footwall country rock.
出处
《华南地质与矿产》
CAS
2001年第1期1-8,共8页
Geology and Mineral Resources of South China
基金
地质矿产部定向研究项目<扬子地台西缘冕宁石棉地区贵金属成矿规律及找矿靶区研究>的部分成果
