辽宁白云金矿床稳定同位素地球化学特征及矿床成因

白云金矿床是辽东地区的一个大型金矿床,其成矿物质来源及矿床成因一直存在争议。本文系统地研究了白云金矿床的氢、氧、硫和碳同位素地球化学特征。研究结果显示:成矿流体中δ~(18)OV-SMOW值变化范围为13.5‰15.9‰,δD_(V-SMOW)为-107‰-83‰,表明成矿流体以岩浆水为主;矿石中黄铁矿的δ~(34)S_(V-CDT)为-8.3‰2.9‰,以富轻硫和贫重硫为特征,与辽河群围岩中黄铁矿的硫同位素组成(δ~(34)S_(V-CDT)为7.0‰18.7‰)有明显差异;矿石中方解石的碳同位素δ~(13)C_(V-PDB)为-2.2‰-0.4‰,类似于火成碳酸岩或地幔包体来源的碳同位素特征,也与辽河群大理岩的碳同位素组成明显不同。成矿元素特征对比也显示,成矿物质来源与辽河群没有必然联系。综合矿床地质特征和地球化学特征,认为白云金矿床是与深部岩浆流体活动有关的岩浆热液型金矿床。

Stable Isotope Characteristics and Ore Genesis of the Baiyun Gold Deposit,Liaoning Province

The Baiyun gold deposit is one of large gold deposits in eastern Liaoning Province,with many controversies on ore-forming material source and ore genesis.This paper presents systemic researches on stable isotope geochemistry of H,O,S and C in this deposit.The δ18 Ov-sMow and δDwsMow values of the ore-forming fluid range from 13.5‰ to 15.9‰ and from-107‰ to-83‰,respectively,which indicates that the ore-forming fluid is mainly composed of magmatic fluids.δ34 SV CDT values of pyrite grains in the ores range from-8.3‰ to 2.9‰,with enrichment of 32S and depletion of 34S,and have great difference from the sulfur isotope composition of surrounding rocks (7.0‰ ～ 18.7‰).δ13 CV-PDB values of the calcite in the ores range from-2.2‰ to-0.4‰,suggesting its igneous carbonates or mantle xenoliths source and obviously different from the composition of carbon isotope of marble of Liaohe Group.The comparison of ore-forming elements in the different geological bodies shows that the source of ore-forming material has no necessary correlation with strata of the Liaohe Group.The geologic and geochemical features of the Baiyun deposit suggest that this gold deposit belongs to the magmatic hydrothermal gold deposit related to hypomagmaism.