東北地方新第三系貝類化石の古水深指標とその適用  [in Japanese] Paleobathymetric indexes of the Neogene molluscs in Tohoku District and their implications  [in Japanese]

Based on an actualism and a concept of parallel community, we select about 80 molluscan genera for the estimation of paleobathymetric index from the Neogene of Tohoku District. Among 7000 living molluscan species in the Japanese waters, about 2000 species which are common in the Neogene deposits of Tohoku District are selected, and checked their bathymertric ranges in reference to the published malacological data. Consequently, wecan show generic characteristics corresponding to water depths as a guideline; 0 m, 20 m, 30 m, 50 m, 100 m, 150 m, 200 m and deeper than 200 m, respectively (Table 1). Neogene paleobathymetric successions of Tohoku District are reconstructed along both sides of the Pacific Ocean (Fig. 3) and the Sea of Japan (Fig. 4) and one traverse section of the Honshu Arc from Atsumi through Shinjo to Sendai areas (Fig. 5). Some transgressive and regressive successions are clarified in reference to the biochronologic scale.