海洋科学2016，Vol.40Issue(5)：141-150,10.DOI:10.11759/hykx20150513001
冲绳海槽黑色与白色浮岩特征及其对岩浆演化的指示
Petrological characteristics of black and white pumice from the Okinawa Trough：Implications for magmatic evolution
摘要
Abstract
Pumice is the most widely distributed volcanic rock in the Okinawa Trough and includes black and white pumice. To better understand the black and white rock characteristics and genesis of this pumice, we employed arti-ficial sand and element geochemistry analysis techniques to investigate the two types of pumice elements and min-eral composition characteristics. Specifically, we used artificial panning and element geochemical data to determine the characteristics and genesis of the black and white pumice. The element compositions of these two pumice species are nearly uniform and belong to the rhyolite category. On the basis of the chondrite-normalized rare earth element (REE) abundances, we observed light REE enrichment in all samples with negative abnormal Eu. All samples were rich in incompatible elements. The physical features of the pumice led to their color differences. The petrology of the pumices displayed only minor variances, such as (1) white pumice contained two species of zircon and pyroxene and black pumice only zircon and pyroxene; (2) bead-shaped structures were only distributed in the black pumice wherein titanium magnetite and ilmenite surrounded by glass were distributed. Based on the above petrological characteristics of the pumice, we could depict the evolution process of the plumbing system. The magma plumbing systems producing the white and black pumice share the same mantle source that generated parental basaltic magma. Primary and deeper magma chambers that formed the white pumice developed while the parental magma was plumbed into the crust. The shallow magma chamber that produced the black pumice was connected to a branch of the magma conduit of a deeper chamber. During the evolution of these two plumbing systems, magma was repeatedly added to the chambers. In addition, the redox feature of the magma gradually transformed from oxidative to reductive during the evolutionary process.关键词
冲绳海槽/浮岩/人工重砂/元素地球化学/岩浆演化Key words
the Okinawa Trough/pumice/artificial panning/geochemical composition/magmatic evolution分类
海洋科学引用本文复制引用
廖仁强,黄朋,胡宁静,李安春..冲绳海槽黑色与白色浮岩特征及其对岩浆演化的指示[J].海洋科学,2016,40(5):141-150,10.基金项目
国家重点基础研究发展计划(2013CB429702) （2013CB429702）
中国科学院战略性科技先导专项(XDA11030302) （XDA11030302）
国家自然科学基金(40606021)@@@@National Key Basic Research Programme of China,2013CB429702 （40606021）
Strategic Priority Research Program of the Chinese Academy of Sciences, No.XDA11030302 （）
National Natural Science Foundation of China, No.40606021。 （）
