Late Cenozoic Stratigraphy and Paleoenvironmental Change of the Coastal Area along the Sea of Japan

对日本海沿岸沿着的北海道西北、北海道西南、青森、秋田山形、新泻、信州、北陆和山阴8个省的晚新生代地层进行了研究。根据生物地层学、火山岩地层学和年代地层学等方法对各省进行了岩石地层划分，完成了从北海道到山阴的Heagene carrelail，并据此绘制了五幅以上的各省晚第三纪古地理图，时间间隔约为50万年至100万年。据此绘制了6幅日本海边缘新第三纪古地理图，从化石（硅藻、有孔虫、放射虫、软体动物）、沉积相和构造相等方面研究了日本海新第三纪古海洋环境。主要研究结果和存在的问题如下： ...更多信息 日本东北部中中新世晚期。提出了粗粒物质沉积和海底扇形成的几种模式.讨论了硅质沉积物的焦点变化、沉积环境和沉积速率。泥岩中的有机质（干酪根）可用于沉积环境的重建。本文对日本海东缘区的有孔虫、海鞘和海洋脊椎动物组合等化石的地理和地层分布进行了研究，讨论了它们的变化，并提出了日本海东缘区的重要海洋事件。中中新世早期，在热带环境下开始大海侵，没有热带动物群和植物群：中中新世开始岛弧隆升，温带组合出现，日本海扩张和加深，形成类似现代日本海的深海环境;晚中新世，在日本东北部的卡迪勒拉和边缘海出现陆地，建立温带太平洋区：上新世中期，发生了剧烈的地壳运动，寒温性海洋生物南移。阐明了古环境变化与组合的关系。少

Late Cenozoic stratigraphy was examined in eight provinces along the borderland of the sea of Japan, namely northwest Hokkaido, southwest Hokkaido, Aomori, Akita-Yamagata, Niigata, Shinshu, Hokuriku and San-in provinces. Lithostratigraphic classification inclusive of biostratigraphy, tephrastratigaraphy and chronostratigraphy, was established in each province and Heagene carrelatiorl from Hokkaida to San-in were completed.According to it, more than five sheets of Neogene paleogeographical maps of each province wore drawn at intervals of about half million to a million year. Moreover, in accordance with them six sheets of Neagene paleageographical map in the borderland of the sea of Japan were drawn.Neagene marine environment in the palea-sea of Japan was studied from the viewpoint of fossil (diatom, foraminifera, radiolaria, molluscs), sedimentary and tectonic faces. Some of important results and problems are cited as follows.The study an turbidits faces of sedimentary basin during mid … More dle Middle Miocene in northeast Japan was advanced. Some models an sedimentation of coarse materials and formation of submarine fan were proposed. Focus change of siliceous sediments, its sedimentary environment and the sedimentary ratio were discussed. Organic matters (kerogen) in mudstone is available for reconstruction of sedimentary environment. Geographical and stratigraphical distributions of fossils, such as foraminifera, malluscs and marine vertebrate assemblages were examined and their changes were discussed.From the results, important marine events in the east marginal area of the sea of Japan are mentioned. During early Middle Miocene time, commencement of large transgression under tropical environment, nothing of tropical fauna and flora; During Middle Miocene commencement of upheaval of island arc, appearance of temperate assemblage, expansion and deeping of the sea of Japan, formation of deep sea environment like the recent sea of Japan; during Late Miocene time, appearance of land area, in cardillera of northeast Japan and marginal sea, establishment of temperate Pacific realm: During Mid-Pliocene time, occurrence of serious crtistal movement and southing of cool-temperate marine organisms. The relationship between the change of paleoenvironment and assemblages was made clear. Less