Ore geology and fluid inclusion geochemistry of the Sandaozhuang Mo-W deposit in Luanchuan county, Henan province

河南省栾川县三道庄钼钨矿床是东秦岭钼矿带的5个超大型钼矿床之一,产于华北克拉通南缘,形成于燕山期碰撞造山体制的后碰撞构造环境。矿体定位于燕山期花岗斑岩与栾川群浅变质碎屑岩-碳酸盐建造的外接触带,矿石构造主要是浸染状和网脉状,广泛发育长英质脉、辉钼矿脉、石英-辉钼矿脉、石英-黄铁矿脉、碳酸盐-萤石脉等。围岩蚀变类型复杂,主要有矽卡岩化、钾化、硅化、绿帘石化、绿泥石化、绢云母化、碳酸盐化、萤石化以及黄铁矿化、辉钼矿化等硫化物化,矿石类型主要是矽卡岩型和角岩型,属于典型矽卡岩型钼钨矿床。成矿过程分为矽卡岩阶段(早)、石英-硫化物阶段(中)和石英-碳酸盐(晚)3个阶段。流体包裹体有CO_2-H_2O、...The Sandaozhuang Mo-W deposit in Luanchuan County, Henan Province, is one of the five giant Mo deposits in the East Qinling nolybdenum belt. Occurring in the southern margin of the North China craton, it was formed in the Yanshanian post-collisional setting of the inter-continental cotlision regime. Orebodies are hosted in outer contact zone between the Yanshanian granitic porphyry and the plastic-carbonate strata within the Luanchuan Group. Disseminations and stockworks, including associations of feldspar-quartz, molybdemite, quartz-sulfide, quartz-carbonate and carbonate-flourite, are two common ore structures. Major wall-rock alteration includes skarnization, potash alteration, silicification, epidotization, chloritization, sericitization, carbonation, flouritization and sulfidization such as pyritization and molybdenitization. The ores are mined as skarn and hornfels. The ore-forming process can be divided into the early, middle and late stages, namely skarn, quartz-sulfide and carbonate-quartz/fluorite, respectively. Three compositional populations of fluid inclusions can be identified as CO(2)-H(2)O, H(2)O-NaCl and daughter mineral-bearing. The primary fluid inclusiors in early stage minerals are major of CO(2)-H(2)O and daughter mineral-beating, while the late stage mineral only contain the H(2)O-NaCl composition, although all three populations can be observed as primary inclusions in middle stage minerals. Homogenization temperatures of fluid inclusions decrease from 394 similar to 552 degrees C (Early), through 290 similar to 410 degrees C (Middle), and to 140 similar to 290 degrees C (Late), with salinities changing from 20 similar to 60 wt% similar to 67.18 wt% NaCl. eqv (Early), through 6.30 wt% similar to 48.55 wt% NaCl. eqv (Middle), to 3.39 wt% similar to 11.46 wt% NaCl. eqv (Late) respectively. As a consequence, the early-stage fluid was characterized by high temperature, high salinity and high content of CO(2) whereas the late-stage fluid by low temperature, low salinity and low content of CO(2); and the middle-stage was characteristic of fluid-boiling which was recognized as an important mechanism for ore-metals precipitation. The fluid-pressure from early-stage lithostatic to late-stage hydrostatic as the system turned open.SCI(E)中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)23102575-25872