新疆托克逊县榆树沟皂石矿床地质地球化学特征及矿床成因分析

Geochemical Characteristics and Mineral Genesis Analysisi of Saponite Deposit in Tuokexun,Xinjiang

通过野外观察和地球化学元素测定,榆树沟皂石矿床具有两种矿石类型:镁皂石矿和锂镁皂石矿。矿石主要产于镁铁质-花岗岩类与碳酸盐岩地层接触带,矿石中含有矽卡岩类热液变质矿物。微量元素研究表明,华力西晚期黑云母化花岗岩中锂含量56.70×10^(-6),并与中泥盆统阿拉塔格组和早期侵入岩间发生交代变质作用,大量锂元素的带入形成锂镁皂石矿。C,O同位素数值显示,含矿碳酸盐岩的δ^(13)C数值偏低,为-2.6‰~1.9‰,平均-0.55‰;δ^(18)O_(Q-SMOW)值为4.9‰~19.2‰,平均11.5‰;矿化斜辉橄榄岩的δ^(18)O_(Q-SMOW)值为15.80‰,明显因地层流体的混入而升高,表明成矿热液流体具混合流体特征。这为热液蚀变型矿床成因机制提供了有力证据。

Based on field observations and geochemiscal test,we found that the deposit has two kinds of ore： Magnesium-saponite and Hectorite.Rare element data indicate that biotite granite of Late Variscan with high Li being 56.70× 10^-6, which intruded into carbonate formation of Middle Devonian,harzburgite and granite of Middle Variscan accompanied with metasomatic metamorphism,and the high Li is very benefit to the formation of hectorite eventually.Oxygen and carbon isotopes data show the low value （-2.6‰-1.9‰ of δ3 C ,average value is -0.55‰）in mineralized carbonate,while the value of δ^18OQ-SMOW varied from 4.9%0 to 19.2%0,Average value is 11.5‰.The mineralized harzburgite value is 15.80‰ of δ^18OQ-SMOW showing the ore-forming fluid is the mixture of magmatic water and underground water obviously.They are strong proof of hydrothermal alteration type deposit.