湖南铲子坪金矿床地质特征及成因

湖南铲子坪金矿床位于雪峰弧形构造带西南段,是雪峰-金山巨型弧形推覆剪切金锑钨成矿带的重要组成部分,形成于碰撞或后碰撞地质背景下的走滑和逆冲构造事件中。文章通过总结前人系统的硫、铅、氧、氢同位素地球化学特征及成矿时代的研究,并进行了成矿流体特征的研究,在此基础上探讨了铲子坪金矿的成矿物质来源。研究结果显示,铲子坪金矿床矿石略富轻硫,具典型的岩浆硫+变质岩混合硫源特征,铅为壳幔混合铅,主要来自造山带。成矿期流体包裹体均一温度范围主要为140~220℃和260~300℃,盐度w(NaCleq.)范围主要为4%~10%和20%~24%,具有两个阶段成矿的特征,成矿流体为中低温、中低盐度、H2O-CO2-NaCl流体体系,存在流体沸腾现象,成矿流体主要来源于岩浆水,同时有大气降水的加入。成矿物质和成矿流体的来源为地层变质岩叠加印支期的岩浆作用。通过综合分析,初步认为铲子坪金矿床与造山型金矿相似,但具有一定特殊性。

Geological Characteristics and Genesis of Chanziping Gold Deposit in Xuefengshan Area,Hunan Province

The Chanziping gold deposit is located at the southern margin of the Yangtze plate, and is an important part of the Xuefeng-Jinshan giant curved nappe-cut gold-tungsten tungsten metallogenic belt. The Chanziping gold deposit is formed in the strike-slip and thrust structure events under the geological background of collision or post-collision. This paper summarizes the sulfur, lead, oxygen and hydrogen isotopic compositions of ore rocks and the isotopic dating results, and studies the characteristics of ore-forming fluids. The results show that the ore of the Chanziping gold deposit is slightly rich in light sulfur and has typical characteristics of mixed sulfur source of magmatic and metamorphic rocks. Lead source of ores is crust-mantle mixed, mainly from orogenic belt. The homogenization temperature range of fluid inclusions in the metallogenic period is 140-220℃ and 260-300℃, and the salinity ranges from 4%-10%NaCleqv. and 20%-24%NaCleqv. It has the characteristics of two stages of mineralization. The ore-forming fluids are of medium-low temperature, low salinity and H2O-CO2-NaCl fluid system. There exists fluid boiling phenomenon. The ore-forming fluids mainly come from magmatic water, and the addition of atmospheric precipitation. The source of ore-forming materials and ore-forming fluids is stratigraphic metamorphic rocks superimposed by the magmatism of Indosinian period. Through comprehensive analysis, it is preliminarily believed that the Chanziping gold deposit is similar to the orogenic gold deposit, but it has certain special characteristics.