New Perspectives on Us Atlantic Coastal Plain Aminostratigraphy Gleaned From Extensive Analyses of Shell Specimens From Inner Continental Shelf Vibracores

Wehmiller, John F.; Ramsey, K.W.; Howard, Scott S.; Mattheus, C.R.; Harris, Michael S.; Luciano, Katherine

doi:10.1130/abs/2019se-326300

Cited by 2 publications

(1 citation statement)

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“…Seven additional samples, taken from depths that correspond to AMS-14 C samples, were chosen for AAR analysis (Table 1). AAR age estimates are based on comparison of amino acid isomeric forms (Walker, 2005), calibrated to onshore U-series geochronology, and reported as Holocene or Pleistocene (Wehmiller et al, 2004;Wehmiller et al 2019). AAR samples were analyzed at Northern Arizona University's Amino Acid Geochronology Lab.…”

Section: Sediment Coresmentioning

confidence: 99%

Depositional Environments and Stratigraphy of Quaternary Paleochannel Systems Offshore of the Georgia Bight, Southeastern U.S.A.

Long

Hanebuth

Alexander

et al. 2021

Journal of Coastal Research

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Paleochannels are common subsurface geological features beneath inner continental shelves and coastal plains and are important archives of ancient depositional environments. This study, focusing on a 450-km portion of the inner continental shelf of the SE United States, adds to understanding of the timing of paleochannel development, the paleoenvironments in which they formed, and the mechanisms that drove their formation. Integrated analysis of 1089 km of high-resolution seismic reflection data and 12 sediment cores reveals that (1) most paleochannels documented here formed in backbarrier environments (estuarine or lagoonal) and were subsequently filled during transgression or following avulsion, preserving mud-rich, tidally influenced deposits; (2) the preservation of nonmarine deposits is rare;(3) paleochannels are either solitary or amalgamated, forming paleochannel complexes within which they are arranged in multistory (vertically stacked) or multilateral (horizontally offset) configurations, a product of local hydrodynamic conditions, antecedent geology, glacioeustatic cycles, and regional isostatic adjustments; and (4) a general southerly increase in the overall degree of channelization is observed across the Georgia Bight, a function of long-term accommodation, interaction with underlying stratigraphy, and dominant coastal processes. The composition and spatiotemporal distribution of paleochannel systems has implications for understanding the long-term evolution and preservation of complex coastal systems and informing regional Quaternary sea-level reconstructions.

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Section: Sediment Coresmentioning

confidence: 99%

Depositional Environments and Stratigraphy of Quaternary Paleochannel Systems Offshore of the Georgia Bight, Southeastern U.S.A.

Long

Hanebuth

Alexander

et al. 2021

Journal of Coastal Research

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The Quaternary stratigraphic architecture of a low-accommodation, passive-margin continental shelf (Santee Delta region, South Carolina, U.S.A.)

Long

Hanebuth

Lüdmann

2020

Journal of Sedimentary Research

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The Quaternary stratigraphy of the continental shelf offshore of South Carolina consists of stratigraphic units deposited in coastal-plain, shallow marine, and shelfal environments bounded by composite erosional surfaces that developed in response to numerous glacioeustatic cycles and were overprinted by regional uplift. These units are commonly distributed laterally, rather than stacked vertically, a function of the long-term low shelf gradient and the resulting lack of accommodation. Additionally, marine processes such as waves and geostrophic currents can rework both relict and modern sediments across the continental shelf. This study integrates high-resolution geological and geophysical datasets acquired offshore and onshore with existing data onshore into a comprehensive conceptual model describing the Quaternary geologic evolution of the coastal plain and continental shelf within a study area of approximately 8,000 km2. We use seismic facies and core analysis to define stratigraphic units associated with transgressive, regressive, and lowstand systems offshore. Regressive systems include progradational wave- and river-dominated deltaic and shoreface deposits. Lowstand systems consist of a complex network of paleo-incisions produced by regional, Piedmont-draining fluvial systems and smaller coastal plain rivers. Transgressive systems include paleochannel-fill successions dominated by mud-rich, tidally influenced backbarrier deposits, cuspate and linear shelf sand ridges, and transgressive sand sheets and shoals. The low-accommodation setting of the continental shelf influences the stratigraphic record in several ways: 1) the geometry of progradational coastal lithosomes, 2) the development of composite allogenic erosional surfaces, 3) the deposition of widespread, thin transgressive sand sheets, and 4) the restriction of thicker transgressive deposits to paleo-incisions. In this setting, the use of a bounding surface scheme that is hierarchical is preferable to the more common sequence stratigraphic or allostratigraphic convention for several reasons: 1) major erosional bounding surfaces are commonly amalgamated; 2) lower-order surfaces capture internal variability, which is key to the genetic interpretation of stratigraphic units, and 3) stratal stacking patterns typically used to define a sequence stratigraphic framework are rare.

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New Perspectives on Us Atlantic Coastal Plain Aminostratigraphy Gleaned From Extensive Analyses of Shell Specimens From Inner Continental Shelf Vibracores

Cited by 2 publications

References 0 publications

Depositional Environments and Stratigraphy of Quaternary Paleochannel Systems Offshore of the Georgia Bight, Southeastern U.S.A.

Depositional Environments and Stratigraphy of Quaternary Paleochannel Systems Offshore of the Georgia Bight, Southeastern U.S.A.

The Quaternary stratigraphic architecture of a low-accommodation, passive-margin continental shelf (Santee Delta region, South Carolina, U.S.A.)

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