河南省大河沟锑矿床构造-流体与低温成矿  

The Low-Temperature Mineralization of Structurally-controlled Fluids in the Dahegou Antimony Ore Deposit,Henan Province

作　　者：徐进鸿 张正伟[1] 杨晓勇[3] 张建军 史海松 吴承泉[1] 郑超飞 

机构地区：[1]中国科学院地球化学研究所,矿床地球化学国家重点实验室,贵阳550002 [2]中国科学院大学,北京100049 [3]中国科学技术大学地球和空间科学学院,中国科学院壳幔物质与环境重点实验室,合肥230026 [4]河南省国土资源科学研究院,郑州450053 [5]河南发恩德矿业有限公司,河南洛阳471600

出　　处：《地质学报》2017年第12期2739-2756,共18页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41573039,U1603245)资助的成果

摘　　要：大河沟锑矿床分布在中元古界秦岭群变质岩内,矿体产出受双槐树深大断裂及其旁侧断裂控制,是一个构造控矿因素明显的低温热液矿床。为了深入探索它的成矿构造与成矿元素富集的有机联系及成矿机理,选择矿床内典型构造岩开展了构造岩特征和矿石的主微量元素、矿石矿物学、同位素地球化学和包裹体测试等分析。研究结果表明:矿床分布受区域韧性剪切带的控制,矿体围岩的糜棱岩化时限198.6"4.74Ma,并具有成矿元素矿源层的性质;辉锑矿可能在单一环境和封闭条件下形成,有独特的辉锑矿晶体特征峰值,含高的As、Au、Ag、Mo、Hg、Pb和Zn元素;方解石矿物的C—O同位素属于岩浆-地幔来源;辉锑矿硫同位素的值域为δ34S介于1.8‰~2.6‰之间,铅同位素显示地层铅的变化与辉锑矿相近;包裹体成分的测定表明流体具有硫酸盐的性质,局部为重碳酸根型水溶液,以热液改造沉积卤水为特征,成矿作用在还原条件下进行,石英包裹体中含有较高的H2暗示成矿流体具有深源性质。综合研究认为,矿床形成作用是深部热流体沿深大断裂活动,萃取了韧性剪切变形构造带中活动的金属元素,然后在还原条件和低温环境中沉淀成矿,成矿类型厘定为构造-流体制约的变质型矿床。The Dahegou Antimony ore deposit occurs mainly in the metamorphic rocks of Mesoproterozoic Qinling Group, with orebodies controlled by the Shuangkuishu deep fault and its nearby fractures. The deposit should belong to a structurally controlled low temperature hydrothermal deposit. In order to understand the relationship between mineralization structures and metallgenic element enrichment, and mineralization mechanism, we carried out a detailed study of tectonite using mineralogy, isotopic geochemical analysis and fluid inclusion testing. The results show that the distribution of the deposit is controlled by regional ductile shear zones. The mylonitizatioin occurred at 1986±474 Ma and mineralization elements sourced from deep earth. The stibnites were possibly formed under a single, closed environment, and are of typical peak features, and contain high concentrations of Au, Ag, Mo, Hg, Pb and Zn. Carbon and oxygen isotopes of calcite suggest a magma mantle source. The δ34S values of stibnite range from 371‰ to 385‰, while lead isotopes of stratum lead show similar composition of that of stibnites. Composition analyses of fluid inclusions suggest that the fluids were mainly hydrothermally modified sedimentary brines consisting sulfate and locally bicarbonate type aqueous solutions. The mineralization occurred under reducing conditions. The mineralization occurred in the reducing condition. The high content of H2 in fluid inclusions of quartz indicates that the ore forming fluids are characteristic of deep source. Integrated study indicates that the ore deposit formed from precipitation of metallic elements in the reducing and low temperature condition, which were extracted from ductile shear zones when migrating along deep faulting. Therefore, the Dahegou antimony deposit can be determined a structure fluid controlled metamorphic deposit.

关 键 词：辉锑矿 低温成矿 成矿流体 地球化学 秦岭北部 

分 类 号：P618.66[天文地球—矿床学]