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

通过对东亚大陆东缘古近纪陆地和海底盆地的性质和演化的研究，阐明了它们的成因、构造背景和沉积序列。这些盆地可分为西日本海、陆架和弧前海沟三大区，它们的分布、沉积和构造特征各不相同。WJSP占据了本州西部和九州北部，并显示出向西北方向的半雕刻结构。它由中始新世至早渐新世的非海相层序组成，下部经常有煤和火山成因层，上部是上渐新世的浅海层序，以裂谷面为界。它可能与日本海严重打开之前的裂陷槽相当。SP和FTP分别对应于弧前陆棚和弧前深槽盆地。的SP 关于我们 从八重山群岛、钓鱼岛洋脊以西到西九州，FTP的溯源线从九州到琉球南部。SP由非海相和浅海层序组成，构造上以区域褶皱和正断层为特征，并伴有走滑断层。FTP被定义为俯冲复合体，由深海阶地和海沟的深海扇沉积物组成。定义了三个盆地的谷面和两个层序界面。其中始新统与渐新世之间的裂谷面和渐新世中期（30 Ma）的1型层序界面显示出明显的古深度变化，这似乎与海平面变化曲线相关（Haq et al.，1988年）。沉积相、旋回和古水流分析表明，俯冲杂岩的发育与三角洲-扇体系统的发育有关。菲律宾海板块在始新世向东亚大陆俯冲的过程中，南部为海沟侵蚀的挤压滑动边缘，北部为正交会聚边缘。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