拉尔玛金矿床与夏家店金矿床地质地球化学特征对比

THE CHARACTERISTIC CONTRAST OF GEOLOGY AND GEOCHEMISTRY IN LAERMA GOLD DEPOSIT AND XIAJIADIAN GOLD DEPOSIT

夏家店金矿床和拉尔玛金矿床均产于南秦岭地块古生代裂陷海槽沉积区,矿床赋存于上震旦统—下寒武统碳泥硅质沉积岩系中,矿床表现出微细粒浸染状特征。研究认为,两者在成矿地质背景、矿床地质地球化学、控矿构造、成矿时代、矿床成因、矿床类型等方面具有相似性和相应差别:两矿床分别产于东、西秦岭,各居一方;由氢氧同位素特征可知,夏家店金矿床成矿流体显示大气降水特征而拉尔玛金矿床成矿流体表现混合水特征;两矿床铅同位素均投点于造山带与上地壳演化线之间,表明成矿动力来自大陆造山作用;两矿床稀土元素配分模式均为轻微右倾,显示成矿物质对容矿围岩组分的继承;两矿床均为产于寒武系的类卡林型金矿床。

Laerma and Xiajiadian gold depeosits are all located in the sedimentary domain of palaeozoic taphrogeosyncline and hosted in carbonaceous-siliceous-limy sediments and characterized by micro-disseminated Au. The two deposits occur at different localities and they are similar and different in geological background, ore-controlling factors, geological and geochemical characteristics, ore-forming epoch, ore type and genesis etc. H-isotope values indicate that ore fluid in Xiajiadian gold deposit is characteristic of metamorphic water. Their Pb-isotope values fall between the boundaries of upper crustal and orogenic fields showing that they are dynamically formed by orogeny. Their REE patterns decline slightly to right and imply inheritable relation between the deposits and their wall rocks. They are of Carlin-like gold deposits.