Recognizing cryptic environmental changes by using paleoecology and taphonomy of Pleistocene bivalve assemblages in the Oga Peninsula, northern Japan

摘要: Multivariate analyses applied to Pleistocene bivalve assemblages from the Oga Peninsula (northern Japan) discriminate three distinct assemblages. The and their taphonomy were used recognize environmental settings changes. Astarte–Cyclocardia–Glycymeris assemblage indicates shelf environment (below storm wave base) where gravels shells are transported shallower settings. Supply of exotic coarse sediment probably enabled epifaunal bivalves inhabit sea floor. Glycymeris is characterized by dominance G. yessoensis represents current-swept shoreface (above base). Moerella inhabiting bay open-marine conditions diverse deposit-feeders, indicating a moderately land-locked environment, such as an open or mouth. Fine-grained substrata rich in organic matters suitable for deposit-feeders. Ordination also shows along two gradients, bathymetrical one other related conditions. changes explained mainly glacio-eustatic sea-level alternation coastal geomorphology caused local crustal movements. This study suggests that fossil can be powerful tool reconstruct environments depositional dynamics even intensely bioturbated sedimentary facies.