鞍本地区晚太古宙高镁安山岩的成因解释  

Petrogenesis for Late Neoarchean Era High Magnesian Andesites in the Anshan-Benxi Area

作　　者：郭荣荣 李宗辉 黄萧 GUO Rong-rong;LI Zong-hui;HUANG Xiao(Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学深部金属矿山开采教育部重点实验室,辽宁沈阳110819

出　　处：《东北大学学报（自然科学版）》2022年第5期740-747,共8页Journal of Northeastern University(Natural Science)

基　　金：中央高校基本科研业务费专项资金资助项目(N2101008);国家自然科学基金资助项目(41602198).

摘　　要：首次于鞍本地区发现晚太古宙晚期变质高镁安山岩,其主要矿物组合为角闪石+斜长石+云母+石英+少量辉石,并与~2.55~2.52 Ga BIF和变质表壳岩互层产出.全岩主微量元素地球化学结果显示,鞍本地区高镁安山岩发育钙碱性,高MgO,Cr和Ni含量,以及低FeO_( T)/MgO比值等原始岩浆特征,并呈现强分异REE模式和明显Nb,Ta,Ti亏损等典型岛弧岩浆特征,与~2.7 Ga Wawa绿岩带高镁安山岩和显生宙Setouchi地区赞岐质高镁安山岩具有相近的地球化学特征,将鞍本地区晚太古宙高镁安山岩解释为受到俯冲板片熔体交代的地幔橄榄岩部分熔融形成,为鞍本地区晚太古宙晚期存在俯冲机制提供了佐证.The high magnesian andesites(HMAs)are first recognized from the Anshan-Benxi area,which comprise mineral assemblages of amphibole+plagioclase+mica+quartz+minor pyroxene.The Anshan-Benxi HMAs are interlayered with~2.55~2.52 Ga BIF and supracrustal rocks,therefore indicating that they are late Neoarchean products.Whole-rock major and trace geochemical results reveal that the Anshan-Benxi HMAs represent primary magmas with high MgO,Cr and Ni contents,low FeO_( T)/MgO ratios and calc-alkaline features,and are characterized by typical island arc compositions with strongly fractionated REE patterns and negative Nb-Ta-Ti anomalies.Besides,the Anshan-Benxi HMAs are geochemically analogous to~2.7 Ga HMA in the Wawa greenstone belt and Phanerozoic sanukoid HMA in the Setouchi.Taken together,the Anshan-Benxi HMAs are interpreted products of partial melting of mantle peridotites which are previously metasomatized by subducting slab released melts,consisting with a late Neoarchean subduction geodynamic setting in the Anshan-Benxi area.

关 键 词：鞍本地区 晚太古宙 高镁安山岩 活动板块边缘 岩石成因 

分 类 号：TP20[自动化与计算机技术—检测技术与自动化装置]