宁芜盆地热液脉型金铜矿床地质特征——以江苏铜井金铜矿床为例

宁芜盆地分布着众多热液成因的脉型金铜矿床，铜井金铜矿床是区内该类矿床的典型矿床.矿体主要呈脉状、似脉状和透镜状赋存于近北北西向压扭性断裂与古火山机构复合部位，具有等距雁行排列的特点.研究表明，铜井金铜矿床先后经历了早期石英硫化物阶段、中期石英硫化物碳酸盐阶段和晚期碳酸盐阶段.矿石中黄铜矿硫同位素δ34S平均为3.63‰，34S/32S平均为22.139，为幔源硫来源.金、铜成矿物质为白垩系娘娘山组碱性玄武安山质岩浆分异演化到晚期分熔的产物，成矿热液沿着压扭性断裂构造上升，在有利的构造空间富集成矿.流体包裹体均一温度为171~253℃，成矿深度为100~400 m.总体上，铜井金铜矿床属与构造-火山活动有关的中浅成热液充填脉型矿床.

GEOLOGICAL CHARACTERISTICS OF THE HYDROTHERMAL VEIN TYPE GOLDCOPPER DEPOSITS IN NINGWU BASIN:A Case Study of Tongjing Gold-Copper Deposit in Jiangsu Province

Numerous hydrothermal vein type Au-Cu deposits are distributed in the Ningwu basin. Among them Tongjing Au-Cu deposit is a typical one. The ore bodies are hosted in the composite positions of NNW-trending compressive-shearing faults and ancient volcanic edifices in vein, veinoid and lentiform, with the characteristics of isometric en echelon arrangement. Studies show that Tongjing Au-Cu deposit underwent the early stage of quartz sulfide, mid-stage of quartz sulfide carbonate and late stage of carbonate. The sulfur isotope δ³⁴S of chalcopyrite is 3.63‰, averagely, with ³⁴S/³²S of 22.139, suggesting a mantle source. The ore-forming materials of gold and copper are the liquation production in the late period of differentiation and evolution of alkaline basaltic andesitic magma of the Cretaceous Niangniangshan Formation. The ore-forming hydrotherm rose along the compressive-shearing fault structure, and enriched to mineralization in favorable structural spaces. The homogenization temperature of fluid inclusions ranges from 171 to 253℃, with metallogenic depth of 100-400 m. The Tongjing Au-Cu deposit generally belongs to epi-mesothermal filling vein type related to tectono-volcanic activities.