Petrography and geochemistry of basement rocks from five DSDP Leg 60 Sites

Bulk chemistry and trace elements data were measured in 72 samples, selected from 5 basement sections, which have been recovered by Leg 60 drilling (Sites 453, 454, 456, 458, and 459). According to analytical results a metagabbro- metabasalt breccia, deposited about 5 Ma at the westernmost flank of the Mariana Trough (Site 453), was derived from an island arc source. Basalts from the Mariana Trough (Sites 454 and 456) are similar in many respects to midoceanic ridge basalts (MORB). Yet rocks of unusual geochemistry, reflecting the possible influence of arc volcanism, were found among the pillow lavas at the easternmost trough (Site 456). The acoustic basement in the Mariana fore-arc region was formed by submarine eruptions of arc tholeiites (Sites 458 and 459) and peculiar high-MgO andesites related to the boninite suite.本数据集包含72件样品的全岩化学与微量元素分析数据，这些样品采自5个基底剖面，均由大洋钻探第60航次（站位453、454、456、458及459）获取。分析结果显示，采自马里亚纳海槽最西翼（站位453）、沉积于约5 Ma前的变辉长岩-变玄武岩角砾岩，其物源源自岛弧环境。马里亚纳海槽的玄武岩（站位454与456）在诸多特征上与洋中脊玄武岩（mid-oceanic ridge basalts, MORB）高度相似，但在海槽最东端的枕状熔岩（站位456）中，却发现了具有异常地球化学特征的岩石，其成因可能受到弧火山作用的影响。马里亚纳前弧区域的声学基底，由弧型拉斑玄武岩（arc tholeiites，站位458与459）的海底喷发产物，以及与玻安岩组合相关的特殊高镁安山岩共同构成。