胶东金矿集区硫和碳的循环与控矿作用

Circulation and ore controlling mechanism of sulfur and carbon in gold deposit accumulation region of eastern Shandong

胶东金矿集区矿石中普遍含金属硫化物和碳酸盐矿物,某些矿床中还见有富含炭质的断裂破碎带。成矿溶液中含有大量的SO42-、HCO3-、CO2和有机质等的含硫和含碳组分。矿石硫同位素组成明显富集重硫,结合胶东金矿主要成矿时期(早白垩世)特殊的地质背景、同期海水硫酸盐3δ4S平均值(约+16‰)及现代海水沿NE-NNE向断裂倒灌情况,笔者认为,硫的主要来源与海水硫的大量补给有关。而根据碳、氧同位素组成特征分析,形成金矿床中方解石的物源有很大一部分来自前寒武系碳酸盐岩。浅表环境下成矿金属元素及硫、碳等物质在热液对流系统中的大规模循环是成矿的关键,SO42-与S2-之间的临界转化是制约成矿金属元素活化-迁移-聚集的重要因素,而含碳组分(CO32-、HCO3-、CO2和有机质)则有利于A u、Cu、Pb、Zn等元素的活化和迁移,含硫和含碳组分的循环及有关的物理化学反应之间有明显的关联性。

There are many metal sulfides and carbonate minerals associated with ores in Jiaodong gold concentration zone, and the fracture zones containing charcoal were found in some deposits. Abundant SO4^2- ,HCO3^- ,CO2 and organic matter were found in ore-forming solution. S isotope composition of ore was evidently rich in δ^34S. According to the special geologic background during mineralization period （the early Cretaceous period）, the average δ^34S of seawater sulfate in the corresponding period, and the pouring circumstance of modern seawater from sea to land along the NNE--NE trending faults, the main source of S was believed to be origin in seawater sulfur. A majority of calcit source in the gold deposits came from Precambrian marble according to carbon and oxygen isotopes.. The circulation of ore-forming metallic elements, sulfur and carbon on a large scale was the key to mineralization in hydrothermal convection system of superficial part environment. The critical transforming between SO4^2- and S2^-was an important factor which controlled activation, transfer and accumulation of ore-forming. Elements the carbonaceous components （CO3^2-、HCO3^- ,CO2 and organic matter） were in favor of activation and transfer of some metallic elements such as Au,Cu,Pb,Zn. There were obvious relation between the circulation of sulfur, carbon and correlative physicochemical reactions.