【摘要】：河南桐柏老灣金礦床是桐柏-大別(北坡)金銀成礦帶內(nèi)大型造山帶型金礦床之一。本文對(duì)老灣金礦上上河礦段的礦床地質(zhì)和流體地球化學(xué)特征進(jìn)行了研究,旨在查明該礦段的流體成礦過程。根據(jù)礦脈穿插關(guān)系、礦石結(jié)構(gòu)構(gòu)造、礦物共生組合關(guān)系以及黃鐵礦粒度和晶形,將老灣金礦床上上河礦段成礦過程劃分為:石英粗粒自形黃鐵礦(Ⅰ)、石英細(xì)粒半自形-他形黃鐵礦(Ⅱ)、石英多金屬硫化物(Ⅲ)及石英碳酸鹽(Ⅳ)四個(gè)階段。鏡下觀察顯示,礦床中的包裹體類型有含CO2包裹體(LH2O+VCO2+LCO2)、純CO2(VCO2+LCO2)包裹體、液相(LH2O+VH2O)包裹體及少量含子晶包裹體(LH2O+VH2O+S)。第Ⅰ、Ⅱ和Ⅲ階段均可見含CO2、純CO2和液相包裹體,有時(shí)可見含CO2包裹體和液相包裹體共生。流體包裹體顯微測(cè)溫結(jié)果顯示,成礦流體可近似看做中低溫、低鹽度、富CO2的NaCl-CO2-H2O體系,捕獲純CO2和液相包裹體的流體是由含CO2包裹體所代表的NaCl-CO2-H2O流體經(jīng)不混溶形成的,三者在寄主礦物沉淀時(shí),被同時(shí)捕獲而共存。從第Ⅰ階段到第Ⅳ階段,成礦流體溫度從303~379℃逐漸降低到138~195℃,鹽度從4.07%~9.59%NaCl.eq逐漸降低到1.06%~2.74%NaCl.eq。第Ⅰ階段成礦流體產(chǎn)生了不混溶作用,到第Ⅱ和第Ⅲ階段CO2起泡再次激發(fā)了不混溶作用。從第Ⅰ階段到第Ⅲ階段,成礦流體δ18OH2O從6.56‰~9.71‰經(jīng)1.89‰~4.01‰變化到0.08‰,δDH2O從-78.1‰~-64.2‰經(jīng)-79.5‰~-76.3‰變化到-72.6‰,表明老灣金礦床上上河礦段早期成礦流體主要是巖漿熱液,第Ⅱ階段成礦流體中有少量大氣降水加入,到第Ⅲ階段成礦流體中大氣降水的比例明顯加大。
[Abstract]:Tongbai Laowan gold deposit is one of the large orogenic type gold deposits in Tongbai-Dabie (North Slope) gold-silver metallogenic belt. In this paper, the geological and fluid geochemical characteristics of the Shangshanhe formation in Laowan gold deposit are studied in order to find out the fluid metallogenic process in the section. According to the ore vein intercalation relationship, ore structure, mineral symbiotic assemblage relationship, pyrite granularity and crystal shape, the ore-forming process of Shangshanhe formation of Laowan gold deposit is divided into quartz coarse grain self-shaped pyrite (鈪，

本文編號(hào)：2413516