Publication Date:
2022-05-25
Description:
© The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Marine Geology 385 (2017): 114-130, doi:10.1016/j.margeo.2016.10.007.
Description:
Multiple styles of failure, ranging from densely spaced, mass transport driven canyons to
the large, slab-type slope failure of the Currituck Slide, characterize adjacent sections of
the central U.S. Atlantic margin that appear to be defined by variations in geologic
framework. Here we use regionally extensive, deep penetration multichannel seismic
(MCS) profiles to reconstruct the influence of the antecedent margin physiography on
sediment accumulation along the central U.S. Atlantic continental shelf-edge, slope, and
uppermost rise from the Miocene to Present. These data are combined with highresolution
sparker MCS reflection profiles and multibeam bathymetry data across the
Currituck Slide complex. Pre-Neogene allostratigraphic horizons beneath the slope are
generally characterized by low gradients and convex downslope profiles. This is followed
by the development of thick, prograded deltaic clinoforms during the middle Miocene.
Along-strike variations in morphology of a regional unconformity at the top of this
middle Miocene unit appear to have set the stage for differing styles of mass transport
along the margin. Areas north and south of the Currituck Slide are characterized by
oblique margin morphology, defined by an angular shelf-edge and a relatively steep
(〉8°), concave slope profile. Upper slope sediment bypass, closely spaced submarine
canyons, and small, localized landslides confined to canyon heads and sidewalls characterize these sectors of the margin. In contrast, the Currituck region is defined by a
sigmoidal geometry, with a rounded shelf-edge rollover and gentler slope gradient (〈6°).
Thick (〉800 m), regionally continuous stratified slope deposits suggest the low gradient
Currituck region was a primary depocenter for fluvial inputs during multiple sea level
lowstands. These results imply that the rounded, gentle slope physiography developed
during the middle Miocene allowed for a relatively high rate of subsequent sediment
accumulation, thus providing a mechanism for compaction–induced overpressure that
preconditioned the Currituck region for failure. Detailed examination of the regional
geological framework illustrates the importance of both sediment supply and antecedent
slope physiography in the development of large, potentially unstable depocenters along
passive margins.
Description:
The U.S. Geological Survey, the
U.S. Nuclear Regulatory Commission and Coastal Carolina University funded this
research.
Keywords:
Submarine landslides
;
Multichannel seismic data
;
U.S. Atlantic margin
;
Geomorphology
;
Unconformity
;
Sediment supply
;
Stratigraphy
;
Isopach maps
;
Slope gradient
;
Accommodation space
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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