弧后盆地玄武岩(BABB)数据挖掘:与MORB及IAB的对比  

Back-Arc Basin Basalt( BABB) Data Mining: Comparison with MORB and IAB

作　　者：杨婧[1] 王金荣[1] 张旗[2] 陈万峰[1] 潘振杰[1] 焦守涛[2] 王淑华[1] 

机构地区：[1]兰州大学地质科学与矿产资源学院甘肃省西部矿产资源重点实验室(兰州大学),甘肃兰州730000 [2]中国科学院地质与地球物理研究所,北京100029

出　　处：《地球科学进展》2016年第1期66-77,共12页Advances in Earth Science

基　　金：甘肃省科技重大专项计划项目"祁连山造山带西段石板墎铁矿床赋矿层位及找矿预测研究"(编号:1002FKDA042);中央高校基本科研业务费专项资金项目"中祁连西段野马南山火成岩组合及其构造意义"(编号:lzujbky-2013-113)资助~~

摘　　要：弧后盆地玄武岩(BABB)全球分布有限,与板块俯冲有关,位于岛弧外侧,规模小,寿命短,现代BABB主要分布于西太平洋。通常认为,BABB地球化学成分变化较大,包括正常洋中脊玄武岩(N-MORB)、富集洋中脊玄武岩(E-MORB)、岛弧玄武岩(IAB)及少量洋岛玄武岩(OIB)组分。在玄武岩构造判别图中,BABB大多在洋中脊玄武岩(MORB)范围内,说明BABB类似MORB。新的全球MORB数据研究表明,MORB包含了从MORB到OIB及IAB的组分,而BABB相对于MORB更富集Cs,Rb,U,Ba,Th和Pb等不相容元素,有明显的Nb-Ta负异常,表明BABB兼具MORB和IAB的地球化学特征,是俯冲流体及沉积物参与其岩浆作用过程所致,大多是在湿的条件下部分熔融形成的。弧后盆地可分为初始弧后盆地和成熟弧后盆地,前者玄武岩具有明显的岛弧玄武岩的地球化学特征,而后者玄武岩更接近MORB的特征。Back-Arc Basin Basalts（ BABB） distribute narrowly in the world. Currently,BABB are mainly distribute in the western Pacific Ocean outside the island arc in small scales and short lifespan which are related with subduction. It is generally considered that geochemical compositions of BABB vary in a large scale,including NMORB,E-MORB,IAB,and a small amount of OIB. In most of basalt discrimination diagrams,BABB mainly fall into MORB area,suggested that BABB are similar to MORB. New data of MORB shows that MORB contain a series of constituents from MORB to OIB,also IAB,while BABB are mainly composed by MORB and IAB,rarely show OIB components. BABB is generally analogous with MORB whereas the former is enriched in Cs,Rb,U,Ba,Th,Pb,and other incompatible elements,exhibits an obvious Nb-Ta negative abnormal,suggesting that BABB is featured with both geochemical characteristics of MORB and IAB,with subuduction sediments partition during its magmatism process. It is mainly formed by partial melting in wet environment. Back-arc basins are divided into two groups：mature ones and immature ones. Primary back-arc basins share some geochemical characteristics of island arcs while mature back-arc basins exhibit few IAB features and is closer to MORB.

关 键 词：弧后盆地玄武岩 MORB 岛弧 俯冲带 数据挖掘 

分 类 号：P588.145[天文地球—岩石学]