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1 Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964; amadof{at}ldeo.columbia.edu
2 Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964
3 Department of Earth and Environmental Sciences and Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964
Andrew S. Madof is a Ph.D. candidate at Columbia University's Lamont-Doherty Earth Observatory. He received his B.A. degree from Oberlin College in 2000, his M.S. degree from the University of Kansas in 2006, and his M.Phil. degree from Columbia University in 2008. His research focuses on the noneustatic controls on both shallow-marine and deep-water systems and particularly on the role of deformation in modulating accommodation.
Nicholas Christie-Blick is a professor of earth and environmental sciences at Columbia University's Lamont-Doherty Earth Observatory. He completed his Ph.D. at the University of California, Santa Barbara, in 1979, and was a research scientist at Exxon Production Research Company in Houston for three years in the early 1980s. Christie-Blick's research and publications deal with such varied topics as sedimentation processes, crustal deformation, and deep-time Earth history, with emphasis on challenging conventional thinking and resolving outstanding disagreements.
Mark H. Anders is an associate professor of earth and environmental sciences at Columbia University's Lamont-Doherty Earth Observatory. He received his Ph.D. from the University of California at Berkeley in 1989 working with Walter Alvarez, and joined the Columbia faculty that year. He and his students work on a wide range of topics related to faults and the faulting process, including fault growth, the effects of magmatism on extension, and more recently, the mechanics of large block slides.
ABSTRACT
Three-dimensional seismic data from the Fuji basin, a salt-controlled intraslope minibasin in north-central Green Canyon, Gulf of Mexico, reveal complex interactions between gravity- and suspension-driven sedimentation. Seismic volumes for late Pleistocene (
470 ka) to Holocene fill within the Fuji basin consist of approximately 45% mass transport complexes (MTCs), 5% channelized sandy turbidites, and 50% hemipelagites and muddy turbidites. At least ten MTCs within the Fuji basin flowed radially toward its depocenter, either from basin flanks (i.e., intrabasinal) or as a result of larger-scale salt motion (i.e., extrabasinal). Sediment transport directions are inferred on the basis of elongate basal incisions and smaller-scale scours, head scarps, fold orientation within the complexes, and stratigraphic thinning trends at downdip margins. An amalgamated set of three channelized sandy turbidite complexes less than 350 m (1148 ft) thick and 3 km (1.8 mi) across represents the main sand delivery pathway into the Fuji basin. These deposits are thought to be due to shelf bypass, and possibly, to proximity to the Pleistocene shoreline. Hemipelagites and muddy turbidites are homogeneous, and their thickness is relatively consistent at basin scale. This facies represents background sedimentation.
A process-driven model has been developed involving halokinetic autocyclicity as the primary control on sedimentation in the Fuji basin. Passive salt motion accounts better for both the directions of sediment transport and the frequency of late Pleistocene–Holocene MTCs than currently popular eustatic and steady-state bathymetric models. The conclusion is significant in casting doubt on the generally assumed importance of eustasy in controlling off-shelf lowstand sedimentation and in implying marked variations in stratigraphic details at length scales of less than 10 km (6.2 mi).
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