Identification of fluid-mud deposits in sandy shelf successions and its implications

Abstract

This study examined depositional processes of muddy deposits intercalated in coarse-grained sandridge deposits of the Middle Pleistocene Mandano and Ichijiku formations on the Boso Peninsula, central Japan. We identified these intercalated muddy deposits as fluid-mud deposits on the basis of the combination of lithofacies, geometry, bioturbation, and clay fabric. The fluid-mud deposits are interpreted to have formed in response to storm events. Thus, muddy intercalations, which may have formed as fluid-mud deposits, are interpreted to be more common than those having been identified in coastal and shallow-marine sandy successions.