陕西省凤县九子沟铜矿矿床地质特征及成因研究

本文通过对九子沟铜矿床成矿地质背景,矿区地质特征,矿体特征,矿石特征,流体包裹体特征,硫同位素特征等几个方面的综合研究,九子沟铜矿床矿体主要赋存于星红铺组地层中的九子沟-太山庙灰岩单斜层北接触面及其附近,以层状、似层状产出。九子沟铜矿床分为三个成矿期:早期沉积-变质期、中期热液改造期和晚期表生期,中期热液改造期为主要成矿期。流体包裹体特征显示成矿温度主要集中于180~240℃,盐度集中于2.0%~6.0%NaCl,密度为0.68%~0.95%,成矿深度为0.9~3.2km,成矿流体属于低盐度低密度体系。九子沟铜矿δ18OH2O平均为-4.098‰;δDH2O平均为-80.625‰,说明成矿流体主要为大气降水或地下热卤水。δ34S值变化范围为6.21‰~9.37‰,平均7.44‰,说明硫主要来源于地壳,且有少量海水硫酸盐中硫的加入。认为该区矿床属沉积-热液叠加改造型铜矿床。

Study on geological characteristics and genesis of Jiuzigou copper deposit in Fengxian County,Shaanxi Province

In this paper, we comprehensive studied the ore-forming geological background, the characteristics of the mining area, ore body, fluid inclusion and sulfur isotope of Jiuzigou copper deposit. These results showed the main body of the Jiuzigou copper deposit was mainly hosted in Xinghongpu Formation, the north contacting surface of the JiuzigouTaishanmiao limestone monoclinic layer. They were produced in layers and like layers. The Jiuzicou copper deposit was divided into three metallogenic periods: the early sedimentation-metamorphism, the medium-term hydrothermal transformation and the epigenetic period, and the medium-term hydrothermal transformation was the main mineralization period. The fluid inclusions indicated that the ore-forming temperature was at 180~240℃, the salinity was 2.0~6.0% NaCl, the density was 0.68~0.95%, the ore-forming depth was 0.9~3.2 km. The ore-forming fluid was low salinity and low-density system. The average δ18 OH2O of Jiuzigou copper mine is -4.098‰;the average δDH2O is -80.625‰, indicating that the ore-forming fluid is mainly atmospheric water or underground hot brine. The δ34S value ranged of 6.21-9.37‰ with an average of 7.44‰, indicating that the sulfur was mainly derived from the crust and a small amount of sulfur in the seawater sulfate was added. It is believed that the deposit in this area is a sedimentary-hydrothermal superimposed copper deposit.