铜陵地区矽卡岩型独立金矿成矿深度探讨

DISCUSSION ON THE METALLOGENIC DEPTH OF SKARN TYPE GOLD DEPOSITS IN TONGLING AREA, ANHUI PROVINCE

采用矿床地质法和流体包裹体压力计法,对铜陵地区包村、朝山矽卡岩型独立金矿床的成矿深度进行了估算。据成矿相关岩体特征、金矿体延深、矿石特征等推断金矿化发生于浅成—中浅成环境。根据不同矿化阶段石英、方解石中流体包裹体的显微测温结果,估算成矿压力为650×105～850×105Pa,成矿深度介于2.5～3.2km,与矿床地质特征反映的成矿深度基本吻合,也与国内外同类矿床研究结果相符。综合认为铜陵地区矽卡岩型独立金矿床成矿深度为中浅成,脆性构造裂隙空间的压力骤然降低引起的流体不混溶和流体沸腾是金富集成矿的主要原因。

The metallogenic depth of the Baocun and Chaoshan skarn type gold deposits are estimated in this paper based on both fluid inclusions and geological features. Features of the intrusions associated with gold mineralization and the vertical lengths of the gold ore bodies, mineral compositions of the gold ores as well as shapes of the gold minerals in the two mines indicate that the gold mineralization in the two deposits took place in shallow or middle to shallow depths. Homogenization temperature of the fluid inclusions from quartz and calcite formed at various stages are determined. The metallogenic pressure estimated by fluid inclusions is 650×10~5～850×10~5 Pa, equivalent to depth from 2.5 to 3.2 km. Metallogenic depth estimated by fluid inclusions is similar to that estimated by geological features of the deposits. The conclusion can be drawn that skarn type gold deposits in Tongling area were formed at middle to shallow depth. The phase separation and boiling of fluids played an important role in the gold mineralization.