新疆库鲁克塔格地块东南缘钾长花岗岩的地球化学特征及同位素测年

Geochemical characteristics and isotope dating of moyite at the southeastern margin of the Kuruktag block,Xinjiang,China

库鲁克塔格地块东南缘分布有一系列花岗岩体(群)。详细的野外填图工作发现其主体由钾长花岗岩组成,并含有闪长岩包体。较为系统的地球化学研究结果显示,其为次铝质岩石、钙碱性系列,属I型花岗岩,构造环境类似于岩浆弧花岗岩。单颗粒锆石U-Pb离子探针质谱测年结果为430.6Ma±1.6Ma。这一研究结果证明研究区存在加里东期构造岩浆事件,同时暗示该区曾经是整个东天山早古生代岩浆弧的一部分。

A number of granite bodies （a granite swarm） are distributed at the southeastern margin of the Kuruktag block. Detailed field mapping shows that the granite swarm consists predominantly of moyite, containing diorite xenoliths and relatively systematic geochemical study indicates that the granite also contains subaluminous rocks and calc-alkaline rocks. So the granite belongs to I-type granite, which formed in a tectonic environment resembling that of magrnatic arc granite. Single-zircon ion microprobe U-Pb dating gave an age of 430.6±1.6 Ma. This study supports the view that the Caledonian tectonomagmatic event occurred in the Kumktag area and implies that the area have once been a part of the whole East Tianshan magrnatic arc in the Early Paleozoic.