哈密雅满苏铁矿床地质地球化学特征

GEOLOGIC-GEOCHEMICAL FEATURES OF YAMANSU IRON DEPOSIT IN HAMI

矿床位于岛弧带近陆壳一侧。铁矿体滑成矿期断裂交代一充填于下石炭统雅清苏组碱性一钙碱性系列、中基性岩为主的海相火山岩和碳酸盐岩建造中。根据矿区安山质岩类Ｋ２Ｏ含量同岩浆深度的关系图解，多数样品投影在至贝尼奥夫带中心３０～９０ｋｍ的上地帽；Ｆｅ２＋３号矿体中黄铁矿的同位素组成δ３４Ｓ平均为１．９５‰，接近球粒陨石的同位素组成；铁矿脉中方解石的δ１８ＯＨ２Ｏ为８．３１‰，正好在原生岩浆水的δ１８ＯＨ２Ｏ的范围内（７‰～９．５‰）；矿石中矿石矿物磁铁矿与脉石矿物石榴石和矿区火山岩的稀土元素配分型式相似，均属重稀土富集型。因此，成矿物质与矿区的火山岩主要同源于上地帽。该矿床属火山气液交代一充填型。

Yamansu iron deposit is located near continental crust of the island arc zone. The ore bodies occur in marine volcanic-carbonatite formation dominated by alkaline-calc-alkaline series and intermediate-basic rocks of lower Carboniferous Yamansu Formation,which form by replacement and filling along the mineralogenic faults,The relation diagram of K2O content of andesitic rocks with depth of magma shows that most samples are projected in the upper mantle part 30～90 km away from the centre of Benioff zone. The sulphur isotiope compositions of pyrites in ore body No. 2 and No. 3 is 1.95‰ in average,similar with that of chondrites. The value of pyrites in iron veins is 8. 31‰,exactly in the range of primary magmatic water(7‰～9.5‰). The ore minerals (magnetites),vein minerals (loivines), and ore district volcanics own similar REE partition pattern of heavy REE concentration type. So it concluded that both mineralization materials and ore district volcanics were mainly derived from upper mantle,and the the deposit is of volcanic gas -fluid metasomatic-filling type