云南马关火山角砾岩及其包体岩石岩相学和元素地球化学特征及其地质意义  

Petrography and Element Geochemistry and Their Geological Significance for the Volcanic Breccia and Its Xenoliths from Maguan Area in Yunnan Province

作　　者：李春辉[1] 刘显凡[1,2] 赵甫峰[1] 陶专[1] 吴冉[1] 楚亚婷[1] 王艳艳[1,3] 肖继雄[1] 宋祥峰[1] 

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074 [3]成都理工大学材料与化学化工学院,成都610059

出　　处：《地质科技情报》2011年第3期48-56,共9页Geological Science and Technology Information

基　　金：国家自然科学基金项目(4077303140473027);中国地质大学地质过程与矿产资源国家重点实验室开放基金项目(GPMR2007GPMR0509);成都理工大学矿物学;岩石学;矿床学国家重点(培育)学科建设项目(SZD0407)

摘　　要：对云南马关地区的爆破火山角砾岩及其中各类包体岩石开展了系统的岩相学和元素地球化学研究。结果表明,与爆破火山角砾岩有成因联系的岩石有3类:①以爆破火山角砾岩胶结物形式产出的碧玄岩和钾玄岩。②作为寄主岩的碧玄岩和钾玄岩中包含(携带)的尖晶石相地幔橄榄岩包体,进一步划分为两类:一类是具原始地幔性质的岩石,成分较单一,地幔交代作用不发育,代表熔融程度很低的原始地幔残余;另一类是具有明显地幔交代特征的岩石,岩浆起源于受到地幔交代作用的富集地幔。③与尖晶石二辉橄榄岩共生或伴生的蚀变基性超基性岩包体和石英黑云变粒岩或片岩包体,发育微晶金属矿化或硫化物矿化,其元素地球化学特征与寄主岩和具地幔交代特征的包体岩石具有相似性,表明引发交代蚀变的流体是与印度-欧亚大陆俯冲碰撞诱发的软流圈横向地幔流有关的地幔流体,因伴随板片俯冲和富碱岩浆的起源和运移,最初具有熔浆高温性质,当其与富碱岩浆分离,进而参与结晶成岩,并在引发持续交代蚀变的过程中,不仅进一步引发壳幔混染,同时流体温度降低,而且导致流体性质相应由熔浆向液相转化。上述富碱岩浆和地幔流体交代作用的深部过程机制,在微观上可见伴随微晶金属矿化或硫化物矿化,在宏观上则与该区广泛发育的富碱斑岩型多金属矿床或与富碱岩浆活动有关的远程中低温热液矿床存在必然的内在制约关系。There are kinds of xenoliths in volcanic breccia from Maguan area in Yunnan Province.Systemically petrological and geochemical studies of the host rocks and their xenoliths show that they can be classified into three groups,①basanlte and ultrapotassic rocks as cements of volcanic breccia rocks,②spinel mantle peridotite which can be further divided into two groups.The one is primitive peridotite which stands for residues of low partial melting primitive mantle,and the other one is metasomatied peridotite which origins from depleted mantle and contaminates with slab fluid.③an altersted basic-ultrabasic rock,whose protolith is not known still,and some metamorphic xenoliths are discovered.They develop black opaque materials and various alterations,such as chloritization,carbonatation,serpentinization and uralitization,companied by metalliferous mineralization and sulfidization.The geochemical similarities of altersted basic-ultrabasic rock,metamorphic xenoliths and metasomatied peridotite suggest that mantle fluid from lateral asthenosperic mantle flow resulted by collision and subduction of India-Eurasia initiates alterations,and contaminated with slab fluid,which makes the mantle fluid change from melt of high temperature to hydrothermal fluid of relative low temperature.The mechanism of alkaline magma and mantle fluid can be manifested metalliferous mineralization and sulfidization in microcosmic,and have something to do with polymetal ores related to alkaline porphyry and long-distance middle-low hydrothermal deposits.So,studies of volcanic breccia rocks,basanlte and mantle xenoliths are of great significance for deep mineralization principles at western Yunnan Province.

关 键 词：包体岩石 岩相学 元素地球化学 流体演化 云南马关 

分 类 号：P586[天文地球—岩石学] P595[天文地球—地质学]