Chapter 3 History of continental shelf and slope sedimentation on the US middle Atlantic margin

Abstract

We describe sedimentation on the storm-dominated, microtidal, continental shelf and slope of the eastern US passive continental margin between the Hudson and Wilmington canyons. Sediments here recorded sea-level changes over the past 100 myr and provide a classic example of the interplay among eustasy, tectonism and sedimentation. Long-term margin evolution reflects changes in morphology from a Late Cretaceous -Eocene ramp to Oligocene and younger prograding clinothem geometries, a transition found on several other margins. Deltaic systems influenced Cretaceous and Miocene sedimentation, but, in general, the MaastrichtianPalaeogene shelf was starved of sediment. Pre-Pleistocene sequences follow a repetitive model, with fining-and coarsening-upward successions associated with transgressions and regressions, respectively. Pleistocene-Holocene sequences are generally quite thin (,20 m per sequence) and discontinuous beneath the modern shelf, reflecting starved sedimentation under high rates of eustatic change and low rates of subsidence. However, Pleistocene sequences can attain great thickness (hundreds of metres) beneath the outermost shelf and continental slope. Holocene sedimentation on the inner shelf reflects transgression, decelerating from rates of approximately 3-4 to around 2 mm a 21 from 5 to 2 ka. Modern shelf sedimentation primarily reflects palimpsest sand sheets plastered and reworked into geostrophically controlled nearshore and shelf shore-oblique sand ridges, and does not provide a good analogue for pre-Pleistocene deposition.

Back To Basics of Sequence Stratigraphy: Early Miocene and Mid-cretaceous Examples from the New Jersey Paleoshelf

“…1). As noted here and elsewhere (Van Wagoner et al 1987;Donovan 2010;Miller et al 2014), the clinoform rollover may be many hundreds of kilometers landward of the structural shelf break. We thus use the geometric terms topset, clinoform rollover, foreset, and bottomset ( Fig.…”

The sedimentary imprint of Pleistocene glacio-eustasy: Implications for global correlations of seismic sequences

“…Slope sedimentation can be linked to both sea-level change and sediment supply, with spatial and temporal variability occurring in both interglacial cycles and glacial cycles. On the modern New Jersey slope, surface samples show a largely in situ benthic biofacies (Miller and Lohmann, 1982) with visual observations of largely hemipelagic drape and sporadic turbidity-current activity in some canyon thalwegs; in contrast, the last glaciation shows considerable evidence of widespread transport across the slope (McHugh et al, 1993;Pratson et al, 2007;Miller et al, 2014). The interplay between depositional and erosional slope processes results in complex preservation of the eustatic signal in water depths greater than ~120-140 m (i.e., below the lowest lowerings of Pleistocene sea level).…”

“…Canterbury Basin is not the only margin at which lowstand deposits are patchy or missing from shelf and upper-slope settings. Latest Pleistocene low-stand deposits are missing on the inner-middle continental shelf of the New Jersey, Virginia, and North Carolina margins, and at ODP Site 903 on the New Jersey upper slope (Christensen et al, 1996;Mallinson et al, 2010;Miller et al, 2012Miller et al, , 2014. On the New Jersey shelf, lowstand (MIS 2) and transgressive deposits (early MIS 1) are primarily found as incised valley fills in channels (Goff et al, 2005;Nordfjord et al, 2005;Christensen et al, 2013).…”

The role of deep-water sedimentary processes in shaping a continental margin: The Northwest Atlantic

“…During glaciations, a shelf-edge ice margin shed sediment and cold dense water directly to the slope (Myers and Piper, 1988;Hesse, 1989;Wang and Hesse, 1996;Hesse et al, 1999;Piper, 2005;Roger et al, 2013;Shaw et al, 2014). The same effects may be a result of lower sea levels and subaerial exposure of the shelf, particularly along segments that were not glaciated to the shelf edge (e.g., Carey et al, 2005;Brothers et al, 2013;Miller et al, 2014). All three turbidity-current initiation mechanisms (transformation of failed sediment, hyperpycnal flow from rivers or ice margins, and resuspension of sediment near the shelf edge by oceanographic processes) described by Piper and Normark (2009) are likely at play along these margins.…”