Reconstruction of high-resolution paleogeography in the Plio-Pleistocene

通过对上新世-更新世大规模火山喷发所形成的大范围teparas的对比，研究了日本晚新近纪沉积盆地的地层学和年代学。这些地质资料揭示了日本几个主要平原的古地理和地貌发育。本研究的主要结果如下：1。我们在4 Ma（百万年前）至1 Ma之间发现了至少12层广泛分布的上新世-更新世tephra，其中包括来自九州中部1.3 Ma的Shikito-Yallowl tephra。这些记录标志着数十万年间隔的突出时间指标，对提高上新世—更新世沉积物的精度和分辨率作出了重大贡献。本研究发现的酒井火山灰（4.1Ma）是日本已知最古老的广泛分布的火山灰，由极细的火山玻璃组成，具有碱性石化成分。本研究促进了关东平原地下钻孔岩心样品中a…More sh层与渤索半岛和多摩山的灰层之间广泛存在的火山灰的相关性。利用这些地层资料，揭示了关东平面西部0.6Ma的古地理和福冈-鸭谷川断裂带的活动。4 .关东平原地下地质构造经火成岩研究改善，表明K区活动断裂的运动是日本海打开期15Ma形成的老基底断裂的复辟。本研究收集了北海道不同地区的Tephra数据。揭示了托雅火山在更新世的活跃史。通过地层年代学研究，详细揭示了上更新世宫崎平原的地层和地貌发育。通过精确的泥层对比，揭示了更新世浅间火山活动与浅间火山泥流流出过程以及该地区地貌发育的关系。将本研究改进的热体对比和年代学技术应用于埃塞俄比亚古人类研究。少

Stratigraphy and chronology of the late Neogene sedimentary basins in Japan were investigated through the correlation of widespread teparas derived from the huge volcanic eruption in the Plio-Pleistocene. The paleo-geography and landform development of several major plains in Japan were revealed by these geological data. Main results obtained by this study are as follows.1. We found at least 12 layers of widespread Plio-Pleistocene tephras between 4 Ma (million years ago) to 1 Ma including Shikito-Yallowl tephra from at 1.3 Ma from mid-Kyushu. These tephras mark the prominent time index of several hundred thousand years interval and greatly contributed to the advancement of accuracy and resolution of Plio-Pleistocene sediments.2. The Sakai volcanic ash (4.1Ma) which found in our research is the oldest widespread tephra known in Japan and consists of very fine volcanic glass with alkalic petrochemical composition.3. This study promoted the correlation of widespread tephras between the a … More sh layers in the boring core samples obtained from the underground of the Kanto Plain and the ash layers in Boso Peninsula and Tama Hills. The paleo-geography of the western Kanto Plan at 0.6Ma and activity of the Fukaya-Ayasegawa fault zone were revealed by using these tephra data.4. Underground geological structure of the Kanto Plain improved by tephra researches revealed that the movements of active faults in K into are rejuvenation of the old basement fractures formed at 15Ma in the opening stage of Japan Sea.5. Tephra data in various part of Hokkaido were compiled in this study. We revealed the active history of Toya volcano in the Pleistocene.6. The stratigraphy and landform development of the Miyazaki Plain in the Plio-Pleistocene were revealed in detail by this study using tephrochronology.7. The relationship between the activity of Asama volcano in the Pleistocene and the outflow process of mudflow from Asama volcano an I the landform development of the region were revealed by this study using precise tephra correlation.8. The tephra correlation and chronological techniques improved by our study were applied to the paleo-anthropologic research in Ethiopia. Less