新疆卡特巴阿苏矿区侵入岩的地球化学特征及其地质意义

Geochemical characteristics and geological significance of intrusive rocks in Kateba′asu Mining Area,Xinjiang

新疆卡特巴阿苏大型金矿床古生代中性侵入岩发育,主要岩石类型由闪长岩、花岗闪长岩、二长花岗岩和碱(钾)长花岗岩4个岩石单元组成。通过对其岩石化学、岩石主量、微量和稀土元素特征、岩石化学图解及地质特征分析,中性侵入岩的SiO_(2)含量较高轻稀土富集,重稀土亏损,稀土分布为右倾斜的平行曲线簇,微量元素总体表现为Ti、Sr亏损型,岩石蚀变较强,抗交代蚀变能力弱,P表现为亏损型,Th、K和Zr表现富集型。认为它们基本属同源岩浆演化的产物,为壳—幔混合源的岛弧“I”型花岗岩类,反映岛弧岩浆岩成因,岩浆在上侵过程中与地壳发生了重熔作用,而具以壳源为主的壳幔混合源的成因特点。

The Paleozoic neutral intrusive rocks developed in the Kateba′asu large gold deposit in Xinjiang,and the main rock types are composed of four rock units:diorite,granodiorite,monzonite and alkali(potassium)feldspar granite.It was based on the analysis of its petrochemistry,main rock mass,trace and rare earth element characteristics,petrochemical diagrams,and geological characteristics,neutral intrusive rocks had a higher SiO_(2) content and are enriched in light rare earths,and heavy rare earths were depleted.The distribution of rare earths was inclined to the right.Parallel curve clusters,the trace elements were generally depleted of Ti and Sr,rock alteration was strong,resistance to metasomatic alteration was weak,P was depleted,and Th,K and Zr were enriched.It was believed that they are basically the products of homogenous magma evolution,and they were island arc"I"type granites with mixed crust-mantle sources,reflecting the genesis of island arc magmatic rocks.The magma had remelted with the crust during the process of intrusion.The genetic characteristics of crust-mantle mixed sources dominated by crust sources.