吉林放牛沟多金属矿床成矿物质来源

ORE-FORMING MATERIAL SOURCES OF THE FANGNIUGOU PYRITE POLYMETALLIC DEPOSIT, JILIN

放牛沟多金属矿床的形成与早元古代晚期的火山作用无明显的直接联系 ,矿床和华力西早期后庙岭花岗岩具有共同的物质来源。矿床同位素研究结果表明 :成矿物质主要来自上地幔或下地壳 ,部分来自上地壳。后庙岭花岗岩以Ⅰ型为主 ,并兼有S型特征。成岩物质主要来自深部地壳同熔岩浆 ,有部分火山 -沉积岩系的同化重熔物质加入。w(87Sr) /w(86 Sr)初始比值为 0 70 5也表明成岩物质以深源为主。后庙岭花岗岩物质来源的双重性一定程度上反映了放牛沟多金属矿床成矿物质的双重性———以下地壳为主并兼有上地壳物质来源。

The formation of the Fangniugou polymetallic deposit is unrelated obviously and directly with volcanic activity of the teminal stage of Eealy Paleozoic. The ore deposit possesses the same material sources with the Early Variscan Houmiaoling granites. Isotopic studies of the ore deposit show that the ore-forming substances are mainly derived from the upper mantle or the lower crust and partly from the upper crust. The Houmiaoling granites are mainly of I type with some characteristics of S type. Their rock-forming substances are predominantly derived from syntectic magma of the deep crust with the addition of some assimilationary-remelting substances of volcanic-sedimentary rocks. The ( 87 Sr/ 86 Sr) 0 value is 0 705, implying that the rock-forming substances came mainly from deep sources. The dual nature of the material sources for the Houmiaoling granites reflects to some extent the dual nature of ore-forming material sources of the Fangniugou polymetallic deposit, i.e. the substances came mainly from the lower crust and partly from the upper crust.