冲绳海槽断裂、岩浆构造活动和洋壳化进程

讨论了冲绳海槽断裂、岩浆构造活动特征和它们之间的关系,认为雁行排列的地堑斜交于陆架外缘隆起带,海槽北段断块隆脊、龙王构造带和海槽南段"棉花构造带"可能保留了海槽各幕断陷前的火山岩浆活动特征,而现在活动的吐噶喇火山岛弧可沿海槽南段岛坡追踪到台湾。吕宋岛向台湾的碰撞挤压引起的旋张活动加强了海槽南段的地壳拉张,诱发了地堑内火山岩浆活动,在洋壳化进程中起关键作用,其中最典型的八重山地堑已经形成洋壳。断裂和岩浆活动主要是单向地向岛弧侧迁移,由洋中脊扩张产生的对称条带状磁异常模式难以解释冲绳海槽的洋壳化进程。

Faulting, magmatism and crustal oceanization of the Okinawa Trough

Characteristics of faulting and magmatism of the Okinawa Trough and the relationship between them were focused on.Enechelon grabens are ranked oblique to the continental shelf edge uplift,and the Longwang uplift,the rifting block ridge in the northern trough and the "Mianhua uplift" in the southern trough have possibly preserved characteristics of volcanism and magmatismo ccurred with those rifting phases.The Tokara volcanic arc can be traced to Taiwan along the west slope of the Ry ky island arc.The clockwise rotation of the southern Ry ky-gunt,driven by collision between Luzon and Taiwan,has played a key role in the crustal oceanization,enhancing the crustal extension of the southern trough and inducing volcanic magmatism in those grabens,among which the Yaeyama grabenis a typical example of the presence of oceanic crust.Faultingand magmatism were mainly migrating towards the island are asymme-trically.The crustal oceanization of the Okinawa Trough is difficultly interpreted by the linear magnetica-nomaly model,which is fit for the symmetric spreading of the mid-oceanic ridges.