塔西乌拉根铅锌矿床硫同位素地球化学特征

Geochemical Characteristics of Sulfur Isotope of Uragen Pb-Zn Ore Deposit in the Western Tarim Basin

乌拉根铅锌矿带位于塔里木盆地以西喀什凹陷北部的乌恰凹陷中,该矿床δ34S值-25.9‰~27.5‰,显示出较宽泛的分布范围,本文通过对乌拉根铅锌矿床S同位素的研究,分析了成矿物质来源和矿床形成过程。该矿区硫同位素具有混合BSR作用形成的生物硫和海相沉积的膏岩矿物硫的特征,塔里木盆地西缘的新生界沉积盆地内大量发育的天青石、石膏、重晶石等硫酸盐矿物,为乌拉根铅锌矿床的铅锌矿化提供了充足的硫源。在其成矿作用过程中,盆地流体中的金属物质与来自于膏盐层溶解并进过生物还原作用形成的还原性硫结合导致硫化物的沉淀成矿。乌拉根铅锌矿床属砂砾岩型铅锌矿床。

Uragen Pb-Zn ore deposit is hosted by Mesozoic-Cenozoic strata of Kash depression in the northwestern margin of the Tarim Basin. The sulfide δ34Sv-CDT of Uragen Pb-Zn ore deposit varies from -25.9%0 to 27.5%0, with a wide distribution range. In this paper, S istopic compositions of sulfides from ore bodies in the ore deposit were systematically determined so as to discuss the source of ore-forming material and the genesis or the ore deposit. The characteristics of sulfur isotopes indicate that Uragen deposit has mixed sulfur, and basin fluid activities involves in the reduction and biological effect from the marine sulphate. A large number of celestite, barite, gypsum and other sulfate minerals in Cenozoic sedimentary basins in the western margin of Tarim Basin has provided sufficient sulfur source for lead-zinc mineralization of Pb-Zn ore deposit. In the mineralization process, metallic matter in basin fluid combind with the bacteria reduction of sulfate from the dissolving gyprock lead to sulfide precipitation and mineralization. Uragen Pb-Zn ore deposit is a sandstone and conglomerate type Pb-Zn ore deposit.