Integrated Studies of Layer 3, Southwest Indian Ridge

一般认为，海洋地壳从枕状熔岩的挤出层向下渐变到侵入的片状脉复合体，其下部是辉长岩，最后是底部的橄榄岩。在海洋钻井项目Leg 118中，位于印度洋西南大西洋II型断裂带东部横脊浅层（700米）波切顶的735B地点，在一个单孔中取心了500米长的辉长岩。这是迄今为止获得的最完整的辉长岩层剖面，为进一步了解形成海洋地壳的岩浆过程提供了机会。该项目将发展构造、变质和火成岩地层，并对从735B站点获得的样品进行主要、痕量和稀土化学分析。

The oceanic crust is generally thought to grade downward from an extrusive layer of pillow lavas to an intruded sheeted dike complex underlain by gabbros and finally peridotites on the bottom. During Ocean Drilling Program Leg 118, 500 m of gabbro were cored in a single hole, Site 735B, located on a shallow (700 m) wave-cut summit of the eastern transverse ridge of the Atlantic II fracture zone in the southwest Indian Ocean. This is the most complete section of the gabbroic layer yet obtained and provides the opportunity to gain additional understanding of the magmatic processes responsible for the generation of the oceanic crust. This project will develop a structural, metamorphic and igneous stratigraphy, and obtain major, trace and rare-earth chemical analyses on the samples obtained from Site 735B.