Distribution patterns of siltstone clasts in turbidites and their relation to grain fabric of host turbidites

Abstract

Siltstone clasts are commonly known from turbidites in deep-water successions and have been interpreted to document information regarding depositional processes of host sandstones. Here we studied formative processes of siltstone clasts on the basis of size and fabric of siltstone clasts and of host sandstones.Although siltstone clasts generally exhibit imbrication dipping to upslope directions regardless of depositional features of host sandstones, their size, density, and position in a turbidite bed are variable in response to vertical variations in grain size and grain fabric of host sediments. Therefore, the variation in size, density, and position of siltstone clasts in a single turbidite bed is interpreted to be controlled by temporal variations in the relative rates of suspended-load fallout during a single depositional process of sandstone beds from turbidity currents.