Tectonic Evolution of the Paleogene System in the Eastern Margin of East China Region

研究了东亚大陆东缘古近纪陆上和海底盆地的性质和演化，以阐明其成因、构造背景和沉积序列。这些盆地被划分为三个主要省：西日本海(WJPS)、陆架(SP)和弧前海沟省(FTP)，它们之间的分布以及沉积学和构造特征都有很大的差异。西九州位于本州西部和九州北部，呈半封闭结构，向西北方向发展。它由中始新世至早渐新世陆相层序和上渐新统浅海层序组成，下部以煤和火山岩为主，上部以裂谷面为界。这可能类似于日本海严重开放之前的奥拉克根。SP和FTP分别对应于弧前陆棚盆地和深弧前海沟盆地。SP…更广泛地从尖山岛和钓鱼岛以西延伸到西九州，从九州到琉球南部都可以追溯到ftp。SP由陆相和浅海层序组成，在构造上以区域性褶皱和正断层为特征，并伴有走舰断裂。深水俯冲杂岩是由深海阶地和海沟的深海扇沉积组成的。确定了三个裂陷面和两个层序界面。其中，始新世与渐新世之间的沟槽面和中渐新世(30 Ma)的1型层序界面显示出明显的古深度变化，这似乎与海平面曲线有关(Haq等，1988)。沉积相、旋回和古水流分析表明，俯冲杂岩的发育应归因于三角洲补给扇体系的发育。在始新世菲律宾海板块俯冲东亚大陆的过程中，假设了南向海沟侵蚀的斜滑边缘和北向垂直收敛的边缘。较少

The nature and evolution of the Paleogene basins on land and under the sea in the eastern margin of East Asia continent were examined to elucidate their origins, tectonic settings and sedimentary sequences. Those basins are grouped into three main provinces ; the West Japan Sea (WJSP), Shelf (SP) and Forearc-Trench Provinces (FTP), among which the distribution and the sedimentological and structural features are very different with one another. The WJSP occupies the West Honshu and North Kyushu and shows a half-graven structure trending in a northwestern direction. It consists of the Middle Eocene to Early Oligocene non-marine sequence with coal and volcanogenic beds frequently in the lower, and the Upper Oligocene shallow-marine sequence in the upper, which are bounded by a ravinement surface. It might be comparable to an aulacogen prior the serious opening of the Japan Sea. The SP and the FTP are correspond to the forearc shelf and the deep forearc-trench basins, respectively. The SP … More extends widely from the Yaeyama Islands and west of Diaoyudao Ridge to West Kyushu, and the FTP is traceable from Kyushu to the south Ryukyu. The SP is made up of a non-and shallow-marine successions, and is characterized by the regional folds and normal faults that are accompanied with strike-ship faulting, structurally. The FTP is defined well as the subduction complex and is cmposed of deep-marine fan sediments at deep-marine terrace and trench. Three ravinement surfaces and two sequence boundaries were defined. Among them the ravinment surface between the Eocene and the Oligocene, and the type1 sequence boundary in the mid-Oligocene (30Ma) shows marked changes of paleodepth, that seems to be correlative to the eustatic curve (Haq et al., 1988). The analyzes of sedimentary facies, cycles and paleocurrent suggest that the growing of the subduction complexes were attributed to the development of a delta-fed fan system. The oblique-slip margin with trench erosion on the south and the orthogonal convergent margin on the north were assumed for the subduction process of the Philippine Sea Plate beneath the East Asia continent during Eocene. Less