High Resolution Depositional Architecture of Modern Deep-water Sinuous Channel Inner Bend Deposits: A Comprehensive Comparison from Offshore California
Abstract
High resolution multibeam bathymetry collected from an autonomous underwater vehicle, coupled with chirp subsurface profiles, spanning a variety of deep-water sinuous channel systems across offshore California provide precise imaging of inner bend deposits associated with migrating deep-water sinuous channels. The resolution of the higher frequency chirp profiles reveals stratal geometries on the same scale as outcrop analogs. Detailed mapping of these inner bend deposits suggests all submarine channels investigated in this study migrated by means of punctuated lateral steps rather than by gradual lateral accretion and point bar development, as widely believed. Following a single punctuated lateral step of these channels, a morphologically defined flat deposit was preserved in the stratigraphic record at a higher position adjacent to the newly incised channel thalweg. These morphologically unique deposits are defined as inner bend terraces. Terrace morphometrics were measured in an effort to understand scaling relationships between these deposits and traditional lateral accretion point bar deposits observed in the rock record in subsurface and outcrop. The conceptual model of punctuated lateral migration introduced by original work on the Lucia Chica channel system is further supported by documentation of inner bend terraces across multiple deep-water channel systems from offshore California. New observations and interpretations of terrace deposits across numerous localities strongly suggest that the model of punctuated lateral migration is one that has likely occurred much more commonly in deep-water outcrop and subsurface datasets than has been interpreted to date.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS13C1497W
- Keywords:
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- 1824 Geomorphology: general;
- HYDROLOGYDE: 3002 Continental shelf and slope processes;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3022 Marine sediments: processes and transport;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3045 Seafloor morphology;
- geology;
- and geophysics;
- MARINE GEOLOGY AND GEOPHYSICS