堆積相と堆積環境  [in Japanese] Sedimentary facies andits environments  [in Japanese]

Sedimentological studies for analyzing the facies of clastic sediments and reconstructing the sedimentary environments have made important progress in Japan since the early 1970's. In this paper, studies on the process of transportation and deposition, analysis of lithofacies and reconstruction of sedimentary environment of elastic sediments are reviewed. The following studies have particularly contributed to the sedimentology and geological development of the Japanese Islands. 1) Analytical studies of turbidites of the Cenozoic in the Boso Peninsula. 2) Paleocurrent analysis and examination of mineral composition of sandstone in the Mesozoic and Paleogene strata. 3) Studies on the basement of the Japanese Islands based on the examination of gravels in conglomerates, especially gravels of orthoquartzite, metamorphic rocks and welded tuft. 4) Large-scale examination of submarine slide deposits called olistostrome beds or sedimentary melange. 5) Analysis of sedimentary sequence deposited in terrestrial, transitional and shallow marine envIRonments. Although sedimentological studies have made general advances, some important problems sill remain unsolved. Very little have been clarified regarding the facies of recent sediments deposited in active margin environments. Furthermore, experimental studies have not progressed very much since the 1950's. These points provide a basis for future studies on sedimentology in Japan. Besides, an organization of sedimentologists does not exist in Japan. Formation of such an organization would indeed facilitate the research and education of sedimentology in Japan.