中文摘要:同位素地球化学研究表明，中元古界色洛河群绿片岩相变质岩系是海沟金矿床的重要矿源层，它经历了多次构造、变质和混合岩化作用，特别是在燕山早期强烈构造活动中发生了局部深熔作用，形成了海沟二长花岗岩。受热大气降水的淋滤作用，使岩体内金元素活化、迁移和富集，以含金硫化物石英脉群形式沿NE向裂隙带充填于海沟二长花岗岩中，形成了大型沉积变质、深熔岩浆岩源大气降水热液金矿床。
Abstract:The Haigou gold deposit is located at the eastern terminal of the Huadian gold ore zone in Tilin province, lying along the suture belt between the Old Mongolian oceanic plate and the North China paleoplate．The gold deposit consists of over forty gold-bearing sulfide quartz veins which are distributed northeastward, 1600m in total length, 250 m in width and more than 400m in downward extension. Wall rocks include monzonitic granite, diorite porphyrite and metarnorphic rocks of middle proterozoic Seluohe Group, whose gold abundance varies in the range of 2.42-30 ppb. Wall rocks on both sides of the gold-bearing quartz vein have suffered such alterations as silicification, sericitization and carbonatization. The following are isotope geochemical characteristics of the gold deposit. 1．Sulfur in both ore veins and wall rocks is rich in 32S, and average δ34S values of sulfide are -7.9‰ and -4.1‰ respectively, exhibiting no obvious temporal-spatial variation. δ34S∑S of ore fluids is -8.8‰. It is considered that sulfur might have been derived from volcano-sedimentary-metamorphic rocks．2．δD and δ18O values of Mesozoic meteoric water in this area are -149‰ and -200‰ respectively. During the ore-forming process, oxygen isotope composition of water and rocks varied considerably, and δ18O value of the fluids tended to increase and drift. At the principal ore-forming stage, δD values of the fluids were -126- -100‰, δ18O values 2-6‰, and δ13CCO2, values-7.8- -l3.2‰. Ore fluids were mainly derived from magmatic source-hot meteoric water, Carbon came from deep carbon and organic carbon of strata. 3．Lead in ores and wall rocks is old lead from two-stage evolution, with t1 being 2398 Ma. Model ages of lead in single samples are 1000-1200 Ma, with μvalues nearly 9.73 K/Ar closed age of ores is 143Ma, whereas Rb/Sr isochron age of rock body(wall rock)is 181 Ma. Isotope geochemical studies show that greenschist facies metamorphic rock of Middle Proterozoic Seluohe Group served as the source bed of gold, monzo-nitic granite was formed by remelting of the source bed, and meteoric water was the initial source of ore fluids. It is thus inferred that during the early stage of Yanshanian orogeny, due to the continuous expansion of Mongolian oceanic plate and its subduction towards the bottom of North China plate, strata in this area were intensely folded in company with deep faulting and magmafic-hydrothermal activity, and this led to the formation of the remeltihg magmatic source-hot meteoric water type gold deposit. The rock-forming and ore-forming process might be divided into three epochs consisting of six stages, and the native gold-sulfides-quartz assemblage marks the principal ore-forming stage of gold during which the temperature was in the range of 250-350℃, ore fluids varied from acid to weakly acid, and metallogenic environment was of reduction type.
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刘裕庆.1991.吉林海沟金矿床同位素地球化学和成矿规律研究[J].矿床地质,10(2):131~142.1991.Isotope geochemistry and metallogenic regularity of the Haigou gold deposit in Jilin Province[J].Mineral Deposits10(2):131~142
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