东昆仑哈日扎花岗闪长岩形成时代、 地球化学特征及其构造意义

为探讨东昆仑哈日扎银多金属矿岩浆演化序列及其岩石成因，对哈日扎花岗闪长岩进行了年代学和地球化学研究。结果表明，哈日扎花岗闪长岩LA-ICP-MS锆石U-Pb年龄为423.8±4.3 Ma，形成于晚志留世；地球化学特征显示花岗闪长岩高硅，SiO₂介于71.21%~74.46%；高铝，Al₂O₃含量介于13.48%~14.46%；富钾贫钠，K₂O/Na₂O比值为1.32~1.54；A/CNK介于1.02~1.08，显示高钾钙碱性弱过铝质特征；稀土显示出轻稀土富集，重稀土亏损的右倾配分模式，富集Rb、Th、K元素，亏损Ba以及Nb、Ta、Ti等，具有I到S过渡型花岗岩特征，源区主要为上地壳砂屑岩部分熔融，是区域后碰撞伸展构造背景下的产物。 

THE FORMING AGE AND GEOCHEMISTRY CHARACTERISTICS OF THE GRANODIORITES IN HARIZHA, EAST KUNLUN AND ITS TECTONIC SIGNIFICANCE

In order to probe the genesis and magmatic evolution sequence of the granites in the Harizha sliver polymetallic deposit, geochronological and geochemical studies of the Harizha granodiorite was carried out in this paper. The results show that the Harizha granodiorite has LA-ICP-MS zircon U-Pb age of 423.8±4.3 Ma, indicating that it was formed in late Silurian epoch. It has high contents of SiO₂(71.21%~74.46%), Al₂O₃ (13.48%~14.46%), with K₂O/Na₂O ratios ranging from 1.32 to 1.54,and A/CNK values varying from 1.02 to 1.08, respectively. Thus, the Harizha granodiorite belongs to the high K calc-alkaline weak peraluminous granite. The granodiorite has right declined REE distribution patterns, with strong enrichment of LREE and relative depletion of HREE. It is enriched in Rb, Th, K, depleted in Ba and Nb, Ta, Ti,and has characteristics of the I to S transitional granite. It could be mainly sourced from the partial melting of upper crust gabbros, which is the product of regional post-collision extensional tectonic background.