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The transportation systems of clastic materials on the Earth's surface with reference to the changes of sedimentary system ; -comparison between the modern Japanese Islands and its ancient continental situations-.

参考沉积体系的变化，地球表面碎屑物质的运移系统；

基本信息

批准号：
11640449
负责人：
HOYANAGI Koichi
金额：
$ 0.77万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The followings are the results of this research project :(1) The geological developments of the Gotonada basin since the Pliocene was reconstructed as follows using the seismic profiles.Rift-formation stage : Under the normal fault systems of NW-SE and N-S directions, rift-valley trending NW-SE direction started to open at the southeastern part of the basin about 4 Ma ago. The topography was an estuary of large river and marine transgression was also started...Maximum flooding stage : The subsidence became maximum around 3 Ma, and maximum flooding surface was formed at this stage. The normal fault system of E-W trend was active and the E-W direction of rift-valley became prominent. Warm current input caused the high productivity of plankton.High-stand stage : subsidence of the basin became calm, and the relative sea-level has been kept in high level since 2 Ma to present. But, the delta from the Hikine Peninsula of Kyushu repeated to advance or retreat as controlled by the eustatic sea-level changes. These sediments formed the fourth-order cycles burying the basin.1. It is clarified that the sandstones of the Paleogene Ishikari Group have some variability in chemistry and texture due to the difference of provenance. Especially, it is important that the pores in the sandstone are mostly originated from solution in diagenetic stage.2. Organic chemistry effectively indicate the sedimentary environment of marine sediment, on the basis of the Tertiary sediments in the Niigata oil field, a backarc basin.3. On the basis of the analyses of the Pleistocene sediments from ODP Leg 174A, it became clear that the eustatic sea-level changes have controlled greatly the grain size and sequence style of the sediments on the continental shelves.

（1）利用地震剖面重建了上新世以来Gotonada盆地的地质发展过程：裂谷形成阶段：在NW-SE和N-S向正断层系统的作用下，约4 Ma前，盆地东南部开始出现NW-SE向裂谷。地形为大河入海口，海侵也开始了。最大洪泛阶段：3 Ma左右沉降达到最大，最大洪泛面形成。东西向正断层系统活动，东西向裂谷作用突出。高水位阶段：盆地沉降趋于平静，相对海平面自2 Ma以来一直维持在较高水平。但是，从九州岛彦根半岛开始的三角洲受海平面变化的控制而反复进退。这些沉积物形成了埋藏盆地的四级旋回。阐明了由于物源的差异，下第三系石狩群砂岩在化学和结构上具有一定的变异性。特别是砂岩中的孔隙主要来源于成岩阶段的溶蚀作用.在弧后盆地新泻油田第三系沉积物的基础上，有机化学有效地指示了海相沉积物的沉积环境.通过对ODP 174 A航次更新世沉积物的分析，发现海平面升降对陆架沉积物的粒度和层序样式具有重要的控制作用。