--> Abstract: Stratigraphic Architecture of a Salt-Withdrawal Intraslope Minibasin, North-Central Green Canyon, Gulf of Mexico: Implications for Misinterpreting Sea Level Change, by Andrew S. Madof, Nicholas Christie-Blick, and Mark H. Anders; #90078 (2008)

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Stratigraphic Architecture of a Salt-Withdrawal Intraslope Minibasin, North-Central Green Canyon, Gulf of Mexico: Implications for Misinterpreting Sea Level Change

Andrew S. Madof, Nicholas Christie-Blick, and Mark H. Anders
Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY

Three dimensional seismic reflection data from the late Pleistocene (~470 ka) to Holocene fill of Fuji basin, a salt-controlled intraslope minibasin in north-central Green Canyon, Gulf of Mexico, consist of approximately 45% mass transport complexes (MTCs), 5% channelized sandy turbidites, and 50% hemipelagites and muddy turbidites. Based on geometrical evidence, at least ten MTCs within Fuji basin flowed radially towards its depocenter, either from basin flanks (i.e., intrabasinal) or as a result of larger scale salt motion (i.e., extrabasinal). Channelized sandy turbidites in the basin are characterized by sinuosity. An amalgamated set of three such complexes < 350 m thick and 3 km across, and located near the base of the volume, represents the main sand delivery pathway into Fuji basin. Turbidites are thought to be due to shelf bypass, and possibly, proximity to the Pleistocene shoreline. Hemipelagites and muddy turbidites are relatively homogeneous, and their thickness is consistent at basin scale. This third facies represents background sedimentation.

A process-driven model has been developed identifying halokinetic autocyclicity as the primary control on sedimentation in Fuji basin. Passive salt motion accounts better for both directions and frequency of late Pleistocene-Holocene MTCs than popular eustatic and steady-state bathymetric models. This conclusion is significant in casting doubt on the generally assumed importance of eustasy in controlling off-shelf "lowstand" sedimentation.

Halokinetic autocyclicity can be used to predict turbidite reservoir continuity and connectivity in basins with poorly-imaged mobile substrates, and how the timing of low permeability and porosity MTC seals varies as a function of passive salt motion.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas