吉林放牛沟硫铁多金属矿床成矿成晕物质来源

区域地层岩石中元素丰度及其演化资料说明,早古生代末期的火山作用与放牛沟多金属矿床的形成并无明显的直接联系。从时空关系、物质组分以及矿化和元素在多种介质中的分带规律都表明矿床、原生晕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,成矿成晕物质主要来自上地幔或下地壳,但有部分来自上地壳。后庙岭花岗岩以Ⅰ型为主,并兼有S型特征。其成岩物质主要来自深部地壳同熔岩浆,但也有部分火山-沉积岩系同化重熔物质加入。根据初始~(87)Sr/~(86)Sr比值为0.705成岩物质也应以深源为主。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成晕物质来源的双重性——以下地壳为主并兼有上地壳物质来源。

Ore-Forming And Halo-Forming Material Sources Of The Fangniugou Pyrite Polymetallic Deposit, Jilin Province

Element abundances in regional strata and their evolution suggest that volcanic activity at the terminal stage of Early Paleozoic had no obvious direct connection with the formation of the Fangniugou polymetallic deposit. Space-time relationship, material composition and zonation of mineralizations and elements in various media all indicate that the primary halos of the ore deposit share the same material sources with the Early Variscan Houmiaoling granite. Isotopic studies of the ore deposit: show that the ore-forming and halo-forming substances were mainly derived from upper mantle or lower crust and partly from upper crust: The Houmiaoling granite is mainly of I type with also some characteristics of S type. Its rock-forming substances were predominantly derived from syntectic magma of deep crust with the addition of some asssimilationary- remelting substances of volcanic-sedimentary rocks. (⁸⁷Sr/⁸⁶Sr)₀ value is 0.705, also implying that the rock-forming substances came mainly from deep sources. The dual nature of the material sources for the Houmiaoling granite reflects to some extent the dual nature of ore-forming and halo-forming material sources of the Fangniugou polymetallic deposit, i.e. the substances came mainly from the lower crust and partly from the upper crust.