云南中甸地区浪都矽卡岩型铜矿床矽卡岩矿物学特征

Mineralogical Characteristics of Skarns in Langdu Skarn Copper Deposit,Zhongdian,Yunnan Province,China

浪都矽卡岩型铜矿床位于义敦岛弧南段的中甸岛弧。该矿床矽卡岩矿物有辉石、石榴石、角闪石、绿帘石和绿泥石等。本文利用电子探针对该矿床中主要矽卡岩矿物的化学成分进行测试,结果表明石榴石成分变化于Ad57-94Gr6-41Al1-3之间,为钙铁榴石-钙铝榴石固溶体系列,以钙铁榴石为主;辉石端元组分为Hd78-92Di3-12Jo5-9,以钙铁辉石为主。在钙质矽卡岩中广泛发育铁闪石、铁阳起石、绿帘石、方解石等矿物共生矿物研究表明浪都矽卡岩形成环境经历了早期相对高温、氧化的碱性环境到晚期相对低温、还原的酸性环境。

Langdu skarn copper deposit is an important skarn copper deposit hosted by the transition zone of Triassic Qugasi Formation and intrusive rocks in Zhongdian area,NW Yunnan,China.Its skarn mineral mainly consists of garnet,pyroxene,amphibole,epidote and etc.Using electronic probe,we detailed analyzed the chemical composition of major skarn minerals.Results show that garnet is andradite to grossular solid solution series,ranging in composition of Ad57-94Gr6-41Al1-3.End-member of pyroxene is Hd78-92Di3-12Jo5-9,falling into calcium group.Actinolite,grunerite,epidote,and calcite are abundant.Different mineral assemblages reflect that the environment of skarn formation experienced the conversion from relatively high temperature under oxidation condition to low temperature under reduction condition.