东准噶尔北缘两类钙碱性花岗岩特征及其构造-成矿意义

依据前人对东准噶尔地区花岗岩类年代学和地球化学研究,将东准噶尔北缘钙碱性花岗岩划分为两类：一类为俯冲钙碱性花岗岩;另一类为后碰撞高钾钙碱性花岗岩。岩石地球化学对比研究发现,两类钙碱性花岗岩存在系统差异,兼具有相似性。岩石地球化学特点差异表现为俯冲钙碱性花岗岩,显示亲岛弧岩浆性,后碰撞高钾钙碱性花岗岩具有陆内后碰撞深成岩浆的特点。两者之间的相似性表明,造山带内花岗岩类由俯冲钙碱性→后碰撞高钾钙碱性系列演化是由于俯冲造山向碰撞造山快速转化、空间上位于同一造山带内,源区岩浆有双重性的特点。钙碱性花岗岩产出的构造环境具有多样性,成岩过程受造山带不同演化阶段相应构造背景制约,洋陆俯冲的岛弧环境和陆内造山的后碰撞环境分别是俯冲钙碱性和后碰撞高钾钙碱性花岗岩形成的构造背景。埃达克质岩浆亲和性显示俯冲钙碱性花岗岩与部分后碰撞高钾钙碱性花岗岩均有形成不同背景（岛弧和后碰撞）斑岩型矿床的潜力。后碰撞高钾钙碱性花岗岩与IOCG型矿床的空间联系,表明造山带伸展背景的后碰撞环境,也可能是IOCG型矿床产出的构造背景。两类钙碱性花岗岩构造背景的差异可能初步印证了具有岛弧斑岩型矿床的哈腊苏-卡拉先格尔和IOCG型矿床的老山口南东一带成矿环境的差异。

Two Types of Calcium Alkaline Granite and Their Tectonic-Metallogenic Significance in North Margin of Eastern Junggar

Based on the predecessor study on the granite chronology and geochemistry in eastern Junggar,we divide the calcium alkaline granite of the study area into two types: one is calcium alkaline granite for subduction,the other is high-kalium calcium alkaline for post collision.By contrastively studying the rock geochemistry characteristics of the granitic rock,we found that there are systematic differences between the two kinds of calcium alkaline granite,and at the same time they have similarity.Rock geochemistry characteristics indicate that calcium alkaline for subduction is consistent with island-arc magma,high-kalium calcium alkaline for post collision is relevant with post collision plutonism.The similarity explains that evolution is characteristic with quick conversion from subduction to collision,same spatial location in orogenic belt and duple magma source from the series of calcium alkaline for subduction to high-kalium calcium alkaline for post collision.Diverse tectonic setting of calcium alkaline granite indicates that granite is restricted by different evolutionary backgrounds in orgenic belt.Island-arc and post-collision setting is relevant with calcium alkaline for subduction and high-kalium calcium alkaline for post collision respectively.Adakite magmatic affinity show calcium alkaline for subduction and high-kalium calcium alkaline for post collision partly have capacities of formed porphyry deposits in different backgrounds.The spatial relationship between high-kalium calcium alkaline for post collision and IOCG deposit display stretched post collision setting of orgenic belt is tectonic background of IOCG deposit possibly.Multiplicity of tectonic environment explained primarily the tectonic setting differences between Kalaxiangeer with porphyry mineralization and Laoshankou SE belt with IOCG mineralization.