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Evolution and Architecture of Deep-Sea Channels from High-Resolution AUV Imaging of the Modern Pacific Margin, Offshore Central California

Maier, Katherine L.; Fildani, Andrea; Paull, Charles K.; McHargue, Timothy R.; Graham, Stephan A.; and Caress, David W.
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A complex record of Quaternary seafloor evolution is preserved on the modern Pacific margin, offshore central California. The informally termed Lucia Chica channel system is extensively imaged with Autonomous Underwater Vehicle (AUV) technology between ~930 m and ~1250 m water depth. The relatively small size of the Lucia Chica avulsion belt and its preservation within a tectonically complex margin provide insights into intrinsic controls of deep-sea channel architecture, evolution, and sediment transport. In the Lucia Chica, underfilled channels avulsed (switched position), leaving open channels that were reactivated by flows stripped from younger, adjacent channels. Differences in relief, sinuosity, and levee stratigraphy between adjacent channels correspond to relative channel age and indicate a change in channel morphology and architecture with time. Gradient does not appear to be the primary control because adjacent channels formed on the same gradient. Instead, channel morphologies are interpreted to result from differences in channel maturity (cumulative impact of flows), although flow characteristics may also have contributed. Lucia Chica channel evolution involves erosional channel inception through scouring and incipient channels (defined by linear trains of scours) prior to development of continuous features. Channel narrowing, formation and growth of levees, increasing channel relief and development of sinuosity occurred with increased maturity. In addition to the channel system, at least two sets of depressions are imaged and appear unrelated to channel development. Such subtle features imaged in the Lucia Chica are only revealed with high-resolution imaging technologies and hold important clues about continental margin development.

 

AAPG Search and Discovery Article #90162©2013 Pacific Section AAPG, SPE and SEPM Joint Technical Conference, Monterey, California, April 19-25, 2013