【作者】 卫清； 范宏瑞； 蓝廷广； 刘玄； 姜晓辉； 文博杰；

【Author】 WEI Qing;FAN HongRui;LAN TingGuang;LIU Xuan;JIANG XiaoHui;WEN BoJie;Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences;Institute of Crustal Dynamics,China Earthquake Administration;Institute of Geochemistry,Chinese Academy of Sciences;Division of Geology and Mineral Resources,CNNC Beijing Research Institute of Uranium Geology;

【机构】 中国科学院地质与地球物理研究所矿产资源研究重点实验室； 中国地震局地壳应力研究所； 中国科学院地球化学研究所； 中核集团核工业北京地质研究院地质矿产研究所；

【摘要】 寺庄金矿床位于胶北地体西北缘,招远-莱州金矿区焦家金矿带南段。矿体赋存于焦家主断裂寺庄段下盘的玲珑花岗岩中,以蚀变岩型矿石为主,石英脉型矿石为次。成矿流体可分为石英-钾长石（成矿前）和石英-黄铁矿-金（主成矿期）两个主要阶段。流体包裹体测温结果表明,主成矿期石英中流体包裹体均一温度为133³10℃,盐度为0%¹2%NaCleqv,成矿流体属于中低温、中低盐度的H₂O-CO₂-NaCl体系。根据氢、氧同位素测试结果并结合前人数据发现,石英δ¹⁸O_石英值变化于9.7‰¹4.2‰,δD_H2O变化于-77.7‰^-55.0‰,经计算获得的石英包裹体的δ¹⁸O_H2O值落在-0.5‰⁶.1‰之间,因此推测寺庄金矿床成矿流体为岩浆水与大气降水的混合,且主要为岩浆水,演化到后期可能有部分大气降水参与。硫同位素研究表明,寺庄金矿床与矿带中段的焦家和新城金矿床具有类似的硫同位素组成,其黄铁矿的δ³⁴S值为7.5‰⁹.4‰。这一范围与玲珑花岗岩和胶东群变质岩的硫同位素组成相近,可能暗示寺庄金矿床成矿物质来自中生代花岗岩。利用最新提出的适用于H₂O-CO₂-NaCl三元混合流体的石英溶解度模型,计算发现寺庄金矿床成矿流体中石英溶解度为0.015mol/kg,这与胶东地质事实相符。成矿期热液中的SiO₂含量极低,其对热液物理化学条件的改变极为敏感。随着成矿流体演化到后期可能有部分大气降水的加入,或是流体迁移至容矿构造压力下降导致的沸腾作用使得成矿流体温度下降,造成SiO₂的大量沉淀,改变了残余流体中Au-S络合物的稳定保存条件,进而发生大规模的金矿化事件。这可能是寺庄乃至整个胶西北金矿都发育有强烈的硅化蚀变带以及石英脉型矿体的一个主要原因。更多还原

【Abstract】 The Sizhuang gold deposit,located at the northwestern border of Jiaobei terrain,lies in the southward extension of the Jiaojia gold belt.Ore bodies primarily occur as sulfide disseminates and sulfide-bearing quartz veins,and they are hosted in Linglong granite,consisting the footwall of the Jiaojia main fault at Sizhuang.The ore-forming fluids can be divided into two generations,represented by the quartz-K-feldspar veins（pre mineralization period） and quartz-pyrite veins（main mineralization period）.Microthermometric investigation reveals that fluid inclusions from quartz in the quartz-pyrite veins homogenized at a temperature range of133³10℃,with salinity of 0% 12%NaCleqv.This suggests that the ore-forming fluids are of medium-low temperature,mediumlow salinity H₂O-CO₂-NaCl system.Results of hydrogen and oxygen isotope studies and previous data suggest that ore-forming fluids were a mixture of magmatic and meteoric water with δ¹⁸O_H2O between-0.5‰ to 6.1‰,and δD_H2O between-77.7‰ to-55.0‰.Magmatic water is suggested as the dominant component,which was added by meteoric water in later period.S’ S values of pyrite range from 7.5‰ to 9.4‰,which are close to the Linglong granites and metamorphic rocks of Jiaodong Group,and this suggest that the oreforming materials（Au,S etc.） of Sizhuang gold deposit might have sourced from Mesozoic granites.We computed quartz solubility in the ore-forming fluids of Sizhuang gold deposit,using our newly established model of quartz solubility in H₂O-CO₂-NaCl system up to1000℃ and 1.5GPa,and revealed that quartz solubility is 0.015mol/kg;this is conformed to Jiaodong geological phenomenon.The quartz solubility of ore-forming fluid is very low in the main mineralization period,and it is very susceptible to the physicochemical conditions of the fluid.The SiO₂ will precipitate when the ore-forming fluids evolved in later stage with meteoric water adding or when it transferred to the host structure accompanying pressure dropping,and the stability of Au-S complex in the residual fluid is interrupted,at last it will lead to the large-scale Au precipitation.These may be the cause of the gold mineralization of Sizhuang gold deposit,and may be one important factor controlling the strong silica alteration and formation of quartz veins at Sizhuang and even in the whole Jiaodong area.更多还原