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南马里亚纳海槽岩性比较复杂：有玄武岩，根据标准矿物组合，进一步划分为碱性玄武岩，橄揽拉斑玄武岩和石英拉斑玄武岩；火山碎屑岩，包括凝灰岩和角砾凝灰岩；以及方辉橄榄岩．大部分玄武岩样品是距今五百万年以后形成的，个别岩石样品的形成年龄为八百万年左右．不同类型的玄武岩是含Ｈ２Ｏ的地幔岩块在底辟上升过程中，局部熔融、分离的产物；火山碎屑岩是火山喷发的火山灰、火山砾被水化学分解的物质胶结而成；方辉橄榄岩是地幔岩浆底辟上升直接侵入结晶的产物．
The South Mariana Trough lithology is rather complicated: basalts, further divided into basal basalt, basalt and quartz tholei basalt according to standard mineral assemblages; pyroclastic rocks, including tuff and breccia tuff; and Habeolite. Most of the basalt samples were formed five million years ago, and individual rock samples were formed at around eight million years. Different types of basalts are the products of partial melting and separation of the mantle blocks containing H2O during the ascent of the diapir; volcaniclastic rocks are volcanic eruptions of volcanic eruptions, and the volcanic conglomerates are cemented by the chemical decomposition of water; The rock is the product of direct invagination of mantle magma diapir.