东天山觉罗塔格构造带雅满苏组火山岩的矿物学研究  

STUDY ON THE MINERALOGY OF VOLCANICS OF THE YAMANSU GROUP IN THE JUELUOTAGE TECTONIC BELT,EAST TIANSHAN

作　　者：侯广顺[1] 唐红峰[2] 刘丛强[2] 

机构地区：[1]河南理工大学,河南焦作454000 [2]中国科学院地球化学研究所地球深部物质与流体作用研究室,贵州贵阳550002

出　　处：《矿物学报》2007年第2期189-194,共6页Acta Mineralogica Sinica

基　　金：国家重点基础研究发展规划项目(2001CB409805);2002年度中国科学院西部之光计划项目

摘　　要：东天山觉罗塔格构造带雅满苏组的构造背景一直存有较大争议。斑晶成分和结构的研究可以对岩浆系列、构造背景和岩浆演化的物理化学条件作出制约。本文报道了雅满苏组火山岩中斜长石和辉石斑晶的研究成果。辉石属于普通辉石-顽透辉石系列，部分样品的辉石颗粒与寄主岩达到了岩浆平衡。辉石判别图解表明寄主岩浆属于亚碱性系列，形成于俯冲带环境，与微量元素判别结果相一致。根据辉石-熔体温压计，得到辉石结晶时的温度在1150℃左右，压力相当于5~10 km的地壳深度。雅满苏组火山岩中主体的斜长石属于拉长石，JX-24-1斜长石为中长石，成分和结构特征都表明该颗粒为捕虏晶。辉石和斜长石捕虏晶共同揭示了雅满苏组火山岩在地壳浅部发生了结晶分异和围岩混染的岩浆过程。Much controversy exists on the tectonic setting of the Yamansu Formation in the Jueluotage tectonic belt, East Tianshan, China. Phenocrysts＇ compasition and texture may reflect igneous series, tectonic setting and give the physical and chemical information about magma evolution. This paper reports the research results of plagioclase and clinopyroxene from the Yanmansu Formation. Clinopyroxene crystals are of augite-enstatite series, and some of them are in equilibrium with their host magma on temperature and pressure. The chnopyroxene discrimination diagram shows that the host magma is subalkaline and was formed in asubduction zone environment. This result is in consistency with that of trace element research. The clinopyroxene crystallization temperature is at about 1150℃ and the pressure is in consistency with about 5 - 10 km depth based on crystallization-melt thermobarometric calculation. Most of the plagioclase phenocrysts are labradorite, but plagioclase JX-24-1 is andesine, and this composition difference and its structure indicate that it is a wall-rock xenocryst. Clinopyroxene and plagioclase phenocrysts provide evidence suggesting that the Yamansu Formation experienced crustal assimilation and fractional crystallization at upper crust depth.

关 键 词：雅满苏组 斜长石 单斜辉石 捕虏晶 岩浆系列 构造背景 温压计 

分 类 号：P574.2[天文地球—矿物学] P581[天文地球—地质学]