【摘要】 冲绳海槽的地震反射波组,根据变形程度分为三组,即未变形的A层组,微变形的B层组和严重变形的c层组。局部地区出现D层组。A层组的地质年代可能是更新统至现代的沉积,海槽南段较厚,其旅行时最大近2秒,北段较薄,最薄约0.3秒。B层组可能是上新统的沉积,其厚度变化与A层组相反,南段薄,北段厚。C层组则可能是中新统和比中新统更老的地层。 海槽中充分发育着顺海槽走向的高角度正断层,为海槽的裂陷成因提供了可靠的依据。更多还原

【Abstract】 A seismic reflection survey for investigating the structure of Okinawa Trough was carried out in June, 1982. The seismic strata in the Trough are divided into three layers, the upper layer, the middle layer and the lower llayer, they are Pleistocene, Pliocene and Miocene, respectively. The upper layer is of parallel or subparallel seismic reflection configuration, The reflection interfaces keep primary sedimentary structure, and are easy to be tracked continuously, the energy reflected from which is intensive. The middle layer is folded slightly. The seismic interface of middic layer appears mostly in short curves due to faulting and folding, the energy from which is either strong or weak. The interface can not be tracked in wide area, because the seismic sequences lost primary sedimentary structure already. The lower is a deformed layer. The interface of lower llayer is rough and obscure, the reflection energy from which is so weak that the lojwer layer are even reflection-free or with chaotic seismic reflection configuration.There are several seismic onlaps of stratal configuration for each layer, implicating relative changes of sea level in geological time. Three important sedimentation cycles were found in upper layer, and the progradational reflection configuration can be distinguished in seismic profile DSIII. Numerous contemporary structures, as growth faults and roll over structure, are produced in sedimentation process.更多还原