赤峰红花沟金矿田铅同位素组成特征及其成因意义  

Lead Isotope Composition of the Honghuagou Gold Orefield in Chifeng Area and Its Genetic Implications

作　　者：谢锡才[1] 

机构地区：[1]东北大学黄金学院

出　　处：《岩石矿物学杂志》1998年第2期179-185,共7页Acta Petrologica et Mineralogica

摘　　要：内蒙赤峰红花沟金矿田矿石铅的２０６Ｐｂ／２０４Ｐｂ范围为１５．４７—１６．４９，２０７Ｐｂ／２０４Ｐｂ为１４．６６—１５．８９，２０８Ｐｂ／２０４Ｐｂ为３５．９２—３８．４８。在铅同位素演化图中呈线性排列，反映出两端元的混合，即古老的基底岩石铅与古老的多阶段演化铅的混合。中－新生代岩浆岩和太古代片麻岩等岩石铅的２０６Ｐｂ／２０４Ｐｂ为１７．３—１８．１，２０７Ｐｂ／２０４Ｐｂ为１５．４—１５．７，２０８Ｐｂ／２０４Ｐｂ为３７．２—３８．２，与矿石铅明显不同，表明矿石铅来源与上述岩石无关。而含透辉石斜长角闪岩的铅同位素组成与矿石铅范围一致或接近，两者间可能有成因联系。矿石铅可能主要来源于太古代基底绿岩建造之含透辉石斜长角闪岩。The Honghuagou ore district and the Lianhuashan ore district in the Honghuagou gold orefield of Chifeng area, Inner Mongolia, have the same lead isotopic composition. The Mesozoic_Cenozoic magmatic and volcanic rocks exhibit very similar lead isotopic composition. The lead isotopic composition of Archaean gneiss and Proterozoic migmatitic granite is also close to that of the above rocks. 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb ratios of these rocks are 17.3—18.1, 15.4—15.7 and 37.2—38.2 respectively; ore lead varies in a wide range, with 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb being 15.37—16.49, 14.66—15.89 and 35.92—38.48, respectively. The isotopic composition of rock lead is obviously different from that of ore lead, and the arrangement trend of ore lead has nothing to do with the distribution of rock lead, suggesting that the material source of ore lead is not connected with these rocks. This is quite different from character of other gold deposits in the same ore zone. The lead isotopic composition of diopside_bearing plagioclase amphibolite is consistent with or close to that of ore lead, implying the probable existence of genetic connection between them. In the lead isotope evolutionary diagram, ore lead assumes linear arrengement, suggesting that it might be a mixture of two end members, i.e., a mixture of old basement rock lead and old multi_stage evolutionary lead. The end member of the low radiogenic lead reflects the contribution of the Archean basement rocks which are older than rocks of this area to ore_forming materials, whereas the end member of high radiogenic lead represents old multi_stage evolutionary lead, which is the evolutionary product in a high μ and high W environment. The source rock of ore lead and gold might be mainly diopside_bearing plagioclase amphibolite within greenstone formation of Archaean besement. Being obviously different from lots of ore deposits in the same ore belt, the Honghuagou g

关 键 词：铅 同位素组成 金矿田 矿床成因 

分 类 号：P618.510.4[天文地球—矿床学] P618.510.5[天文地球—地质学]