八方山大型多金属矿床热水沉积岩相特征与矿化剂组分关系  

CHARACTERISTICS OF HYDROTHERMAL SEDMENTARY FACIES IN RELATION WITH MINERALIZER IN BAFANGSHAN POLYMETALLIC DEPOSIT

作　　者：方维萱[1] 刘方杰[2] 胡瑞忠[1] 陈梦熊[3] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学开放研究实验室,贵州贵阳550002 [2]西北有色金属地质勘查局,陕西西安710068 [3]有色金属矿产地质调查中心,北京100814

出　　处：《矿物学报》2003年第1期75-81,共7页Acta Mineralogica Sinica

基　　金：国家重大基础研究规划项目 (2 0 0 1CB40 980 5 ) ;国家杰出青年科学基金项目 (4 992 5 3 0 9)

摘　　要：陕西八方山大型 (金 )多金属矿床赋存在于中泥盆统吉维特晚期的热水沉积岩相中。富SiO2 酸酐型热水同生 交代沉积作用形成热水同生沉积微相 (层状硅质岩 )、热水同生交代微相 (微晶石英岩及硅化灰岩 ) ;富Fe2 + Mg2 + 碳酸盐型热水同生沉积作用形成层状含铜硅质铁白云岩 ;在同生断裂附近 ,因热水液压致裂 隐爆作用形成含铜黄铁矿硅质铁白云石角砾岩 ;富Na+ 铝硅酸盐型 /富Fe2 + 、Mg2 + 碳酸盐型热流体在同生断裂中形成热水充填微相 (穿层脉状钠长石碳酸岩 ) ;低温热卤水 (富F、Ba、B、As、Sb)形成热卤水同生沉积微相。矿质大规模沉淀的地球化学动力学因素为 :在热水沉积成矿盆地中 ,在单一成分热水体系的温度、压力改变而发生快速化学沉淀 ;不同成分、性态的热水混合后 ,强烈的酸 碱作用及Eh pH剧变等 ,触发热水体系失稳 ,引起矿质大规模沉积。 [SiO2 ]和F可能是重要的矿化剂。The Bafangshan polymetallic deposit occurs in the Middle Devonian Fengtai apart pull basin. Based on its sedimentology, mineralogy, petrology and geoc hemistry of the deposit, the geological geochemical characteristics of hydrothe rmal facies are described. Six patterns of these hydrothermal lithofacies were d efined, i.e., hydrothermal syn sedimentation microfacies, hydrothermal syn sed imentation replacement microfacies, mixing hydrothermal syn sedimentation micr ofacies, hydrothermal explosion and fluid pressure fracturing microfacies, hydr othermal filling replacement microfacies and hot brine syn sedimentary microf acies. Silicates with (FeO+Fe 2O 3+MgO) accounting for less than 10% and SiO 2 >70% may have resulted from hydrothermal syn sedimentation. Siliceous fer rodolomitites with (FeO+Fe 2O 3+MgO) accounting for more than 20% and SiO 2 30% to 50% were also derived from hydrothermal syn sedimentation in the subbas in. Ferrodolomitites were produced by Fe Mg Ca rich carbonate type hot water . Polymetallic ores were accumulated as a result of mixing of different componen ts. Ore forming materials were deposited in response to extensive chemical reac tions. F and [SiO 2] in hydrothermal fluids could serve as the mineralizers m ainly responsible for the transport of metallogenic materials.

关 键 词：多金属矿床 热水沉积岩相 热水同生沉积微相 热水同生交代微相 矿化剂 

分 类 号：P618.2[天文地球—矿床学]