Structural classification of Late Cenozoic sedimentary basins in Japan(Morphology and formative mechanism of late Cenozoic sedimentary basins, especially of tilting basin)

Abstract

Many sedimentary basin classifications are known, which are applicable to worldwide petroleum basins, but not to individual small basin in mobile belt. This paper proposes a new system of basin classification adaptable to the Late Cenozoic sedimentary basins in and around the Japanese Islands. Among those basins the three structural types are distinguished: (1) folding basin formed by synclinal subsidence of basin bottom, in some cases with plural depoaxes, (2) collapse basin generated by depression of a crustal block bounded with steep faults, and (3) tilting basin formed by down tilting of fault block, adjoining fault scarp of neighboring block. The many Late Cenozoic sedimentary basins in Japan can be classified on the triangle diagram with endmembers of collapse, tilting and folding basins, i. e. the CFT diagram, Most of the basins are plotted at the ends and the side lines of the diagram. Those at the central parts of side line of the diagram are called collapse-tilting, tilting-folding and folding-collapse basin, respectively. This tentative classification is expected to promote the feedback between structural description and structrural classification of sedimentary basins and the study of basin genesis.