辽宁朝阳小塔子沟-东五家子金矿田地球化学特征

GEOCHEMICAL CHARACTERISTICS OF THE XIAOTAZIGOU-DONGWUJIAZI GOLD FIELD IN CHAOYANG, LIAONING PROVINCE

在朝阳小塔子沟-东五家子金矿田范围内,北地金矿、小塔子沟金矿和东五家子金矿,因距离岩体的远近不同,形成了不同的特征.石英流体包裹体研究表明,位于岩体内接触带的北地金矿为中温、中-深成热液矿床,位于岩体外接触带的小塔子沟金矿为中温、中成热液矿床,远离岩体的东五家子金矿为中-低温、浅成热液矿床.氢、氧同位素研究表明,北地金矿和小塔子沟金矿的成矿流体主要为岩浆水,东五家子金矿的成矿流体为岩浆水和大气降水混合成因.微量元素研究表明,北地金矿矿石以Mo、Bi等元素相对富集为特征,小塔子沟金矿矿石以Cu、Zn等元素相对富集为特征,东五家子金矿矿石以Pb、Ag等元素相对富集为特征.矿床离岩体越远,金矿物中Au/Ag比值越小.

The Beidi, Xiaotazigou and Dongwujiazi gold deposits in the Xiaotazigou-Dongwujiazi gold field have different characteristics for their various distances from the intrusion. Research on fluid inclusions of quartz indicates that the Beidi gold deposit at the inner contact zone of the intrusion is formed under moderate temperature and belongs to meso-hydrothermal deposit, while the Xiaotazigou gold deposit at the outer contact zone of the intrusion is mesothermal and moderately-seated, and the Dongwujiazi gold deposit far away from the intrusion is epithermal deposit. Study on oxygen and hydrogen isotopes shows that the ore-forming fluids of the Beidi and Xiaotazigou gold deposits are derived from mainly magmatic water, while those of the Dongwujiazi gold deposit are from the mixed magmatic and atmospheric waters.Trace element evidences suggest that the gold ores from Beidi deposit is featured by enrichment of Mo and Bi, while the Xiaotazigou is enriched with Cu and Zn, and the Dongwujiazi is rich in Pb and Ag. The further the deposit is from the intrusion, the smaller of the Au/Ag ratios of gold-bearing minerals are.