西藏多不杂铜矿区曲色组砂岩化学组分特征及构造背景

Chemical component characteristics and tectonic setting of sandstone from Quse Group in Duobuza copper deposit,Tibet,China

探讨西藏多不杂铜矿区下侏罗统曲色组砂岩元素地球化学特征,判别其形成的构造背景。通过野外调查取样,测试样品主元素、稀土元素以及痕量元素成分,利用相关图解作图,结果表明,下侏罗统曲色组第二岩段是多不杂铜矿区花岗闪长斑岩的主要围岩,地层中的碎屑岩类型主要为长石石英砂岩,硅化、黄铁矿化与铜金矿化关系密切,岩浆在侵位以前可能发生过分异作用,轻重稀土元素发生了一定程度的分馏,导致LREE富集、HREE亏损。砂岩形成的构造背景是活动大陆边缘。

This paper explores the element geochemistry of the sandstone from the Lower Jurassic Quse Group in the Duobuza copper deposit of Tibet in China and discriminate the tectonic setting of the deposit.By the field investigation and sampling,testing the major elements,REE elements and trace elements of the samples,using the related illustrations to make drawings,it is found that the second rock segment of the Quse Group （J1q2） is the main surrounding rock of the orebody.The main type of clastic rocks is feldspar quartz sandstone.Silicification and pyritization is closely related to copper-gold mineralization.The magma differentiation occurred before emplacement and the light and heavy rare earth elements experienced certain fractionation,leading to the enrichment of LREE and the loss of HREE.Tectonic setting of forming sandstone is the active continental margin.