The Size, Velocity, and Suspended Sediment Distribution of Turbidity Currents Traveling Through Channels, and Their Relation with Morphological Evolution and Channel-Related Deposits

Abstract

Many decades of studies of deposits and seascapes formed by turbidity currents have established that patterns are repeated through time and space, a prominent example being the tendency to form and fill channel conduits. Much more recently, the process-modeling community has made progress in the understanding of the distribution of suspended sediment, velocity, and turbulence in turbidity currents, together shaping the “flow structure”. Thus, now is the time to integrate, and investigate in more detail how the process of sediment erosion, transport, and deposition by turbidity currents is related to observed systematics in the physical products preserved in the geological record. Here, we use results from experimental sandy turbidity current studies and insights from published literature to investigate: (1) The morphodynamic co-evolution of the flow structure and the channel morphology during an elementary cycle. This elementary cycle constitutes three phases: channel establishment, channel maintenance, and channel fill. Understanding of the elementary cycle of channelization can help to establish the organization of fundamental building blocks of stratigraphy, and can be applied in modelling of subsurface occurrences of channel deposits. (2) Determinations of the sediment budget of channels from their morphology, which can be applied to make predictions of sediment volumes stored in correlated bodies down-dip. (3) A comparison between experimental channel shapes and channel-fill deposit metrics obtained from literature, which raises a number of important questions; about the relation between morphological conduits and fill-deposit shape; about the controls on transition from channel formation to channel filling; and about the usefulness of choosing system analogues based on simple channel-fill metric concurrence. Some of these questions need to be addressed before truly predictive application claimed under (1) & (2) is feasible.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015