西藏蒙亚啊矽卡岩型铅锌矿床花岗斑岩地球化学特征

Geochemical characteristics of granite porphyry of Mengya'a Skarn Pb-Zn Deposit in Tibet

对西藏蒙亚啊矽卡岩型铅锌矿床花岗斑岩进行研究,结果表明矿区斑岩具有高硅,中—高铝,低钛、铁、镁以及极低Na2O等地球化学特征。在微量元素上富集Rb、Th、U、Pb等大离子亲石元素,相对亏损Ba、Nb、Ti、Ta、Sr等元素。在稀土元素配分模式上,表现为明显右倾的不对称燕型配分模式。常微量元素的含量及比值特征,显示源岩成分为上地壳贫黏土砂岩。因此认为矿区花岗斑岩的形成可能与印—亚大陆碰撞而加厚的上地壳物质的部分熔融有关。

Through the research on granite porphyry of Mengya＇a Skarn Pb-Zn Deposit in Tibet, it＇s shown that the granite porphyry has high Si, medium-high Al, low Ti, Fe, Mg and has very low Na2O, etc chemical characteristics. Trace elements are characterized by enriched large ion lithophile element Rb, Th, U, Pb, relative lower Ba, Nb, Ti, Ta, Sr, etc elements. The REE elements distribute patterns performance for obvious right asymmetric Yan type. The contents and ratio characteristics of the major and trace elements show that the magma source may be poor clay sandstone of upper crust. Therefore, it＇s inferred that the formation of granite porphyries of Mengya＇a mining area may be relate to the crustal material which thickened by collisional of India-Asian continent on the partial melting.