摘要
内蒙古乌拉山金矿床是近年在我国北方发现的大型金矿床之一。矿床主要由赋存在太古界乌拉山群变质岩地层中一系列石英－钾长石脉和石英脉组成。矿区范围内晚古生代—中生代花岗岩类分布广泛并且同金矿化具密切时、空分布关系。本文对乌拉山金矿床，大桦背花岗岩体和变质岩地层的硫、铅同位素比值进行了系统测定，并解释了不同地质体硫、铅同位素变化特征。研究表明：金成矿作用发生在２４０×１０￣６ａ，成矿物质主要来自大桦背花岗岩体及有关的岩脉，乌拉山金矿床形成过程中，亦有部分非岩浆物质混入。
The newly discovered Wulashan K-feldspar-quartz and quartz vein gold de-posit is located within Late Archean metamorphosed volcano-sedimentary sequ-ences of Wulashan Group, and surrounded by a number of Late Paleozoic gra-nitoid dikes and batholiths in southestern Inner Mongoiia. Sulfur isotope ana-lyses of twenty-one sulfide (galena and pyrite) samples from auriferous K-feld-spar-quartz and quartz veins, plagioclase amphibolite, gneiss and granitoid int-rusions in the Wulashan area reveal that sulfur of the ore-bearing fluids wasmainly derived from a mixed source of Late Paleozoic igneous and Aroheanmetamorphosed volcano-sedimentary rocks. Lead isotope data on plagioclase am-phibolite define a correlation line with the slope corresponding to an age of2498±76 Ma. In contrast, K-feldspar of the Dahuabei granitoid batholith is cha-racterized by high content of radiogenio lead. On the plot, lead isotope datapoints of thirteen saparated galena and pyrite samples from the auriferous veinsystem fall between the area of plagioclase amphibolite and that of Dahuabeigranitoid batholith, and constitute a mixing line. The result of lead isotope studyalso indicates that Late Archean supraorustal rocks were the initial lead sourcefer Dahuabei granitoid batholith, auriferous K-feldspar-quartz veins and quartsveins. Both sulfur and lead isotope data show that lead, gold and other metalelements of the auirferous vein system mainly catne from a mixed source of Alcheanmetamorphosed volcano-sedimentary rocks and Late Paleozoic Dahuabei granitoidbatholith which was probably derived from homogenizeil re-melting of previouslyformed supracrustal rocks during Late Paleozoic tectonic events.
出处
《矿床地质》
CAS
CSCD
北大核心
1994年第2期106-107,共2页
Mineral Deposits
基金
国家青年自然科学基金
关键词
金矿床
铅同位素
石英脉
钾长石
Wulashan of Inner Mongolia, gold deposit, sulfur and leadisofopes, genesis of the ore deposit
