A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland

AM MCCABE, RWG CARTER, JR HAYNES

    Research output: Contribution to journalArticle

    19 Citations (Scopus)

    Abstract

    At Portballintrae, Northern Ireland, a well-preserved emergent facies sequence formed around 17 kyr B.P. as the Late Devensian ice sheet withdrew from the continental shelf. Three main lithofacies assemblages are recognised: (1) At the base of the sequence a massive muddy diamict was formed by resedimentation of an unstable sedimentary apron deposited in a tidewater setting. (2) Rhythmically-bedded sand and mud units contain a wide range of wave diagnostic features and are separated from the underlying diamict by both transitional and wave-eroded planar contacts. Palaeowave calculations suggest deposition in a coastal tract open to Atlantic waves. The. preservation and range of boreo-arctic foraminifera present are also typical of a lower shoreface, storm-influenced setting. (3) Interbedded gravel and sand facies are separated from the underlying rhythmically-bedded facies by a planar wave-cut surface. This facies occurs as crudely organised beds within cross-cutting, shallow scours which are associated with off-shore directed, storm-induced sediment pulses. Overall the coarsening-upwards sequence is explained by tidewater sedimentation during ice wastage, rapid isostatic rebound and isostatic deceleration in the late glacial. An isostatic-tectonic model comprising a forebulge on the outer continental shelf and a peripheral trough on the inner shelf is presented to resolve the apparent discrepancies between onshore and offshore sea-level data.
    LanguageEnglish
    Pages19-34
    JournalMARINE GEOLOGY
    Volume117
    Issue number1-4
    DOIs
    Publication statusPublished - Mar 1994

    Fingerprint

    ice sheet
    continental shelf
    Devensian
    late glacial
    scour
    sand and gravel
    lithofacies
    foraminifera
    trough
    mud
    sea level
    sedimentation
    ice
    tectonics
    sand
    sediment

    Cite this

    @article{249c81c9e241453884beef8743e0ecd7,
    title = "A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland",
    abstract = "At Portballintrae, Northern Ireland, a well-preserved emergent facies sequence formed around 17 kyr B.P. as the Late Devensian ice sheet withdrew from the continental shelf. Three main lithofacies assemblages are recognised: (1) At the base of the sequence a massive muddy diamict was formed by resedimentation of an unstable sedimentary apron deposited in a tidewater setting. (2) Rhythmically-bedded sand and mud units contain a wide range of wave diagnostic features and are separated from the underlying diamict by both transitional and wave-eroded planar contacts. Palaeowave calculations suggest deposition in a coastal tract open to Atlantic waves. The. preservation and range of boreo-arctic foraminifera present are also typical of a lower shoreface, storm-influenced setting. (3) Interbedded gravel and sand facies are separated from the underlying rhythmically-bedded facies by a planar wave-cut surface. This facies occurs as crudely organised beds within cross-cutting, shallow scours which are associated with off-shore directed, storm-induced sediment pulses. Overall the coarsening-upwards sequence is explained by tidewater sedimentation during ice wastage, rapid isostatic rebound and isostatic deceleration in the late glacial. An isostatic-tectonic model comprising a forebulge on the outer continental shelf and a peripheral trough on the inner shelf is presented to resolve the apparent discrepancies between onshore and offshore sea-level data.",
    author = "AM MCCABE and RWG CARTER and JR HAYNES",
    year = "1994",
    month = "3",
    doi = "10.1016/0025-3227(94)90004-3",
    language = "English",
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    A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland. / MCCABE, AM; CARTER, RWG; HAYNES, JR.

    Vol. 117, No. 1-4, 03.1994, p. 19-34.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - A shallow marine emergent sequence from the northwestern sector of the last British ice sheet, Portballintrae, Northern Ireland

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    AU - CARTER, RWG

    AU - HAYNES, JR

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    N2 - At Portballintrae, Northern Ireland, a well-preserved emergent facies sequence formed around 17 kyr B.P. as the Late Devensian ice sheet withdrew from the continental shelf. Three main lithofacies assemblages are recognised: (1) At the base of the sequence a massive muddy diamict was formed by resedimentation of an unstable sedimentary apron deposited in a tidewater setting. (2) Rhythmically-bedded sand and mud units contain a wide range of wave diagnostic features and are separated from the underlying diamict by both transitional and wave-eroded planar contacts. Palaeowave calculations suggest deposition in a coastal tract open to Atlantic waves. The. preservation and range of boreo-arctic foraminifera present are also typical of a lower shoreface, storm-influenced setting. (3) Interbedded gravel and sand facies are separated from the underlying rhythmically-bedded facies by a planar wave-cut surface. This facies occurs as crudely organised beds within cross-cutting, shallow scours which are associated with off-shore directed, storm-induced sediment pulses. Overall the coarsening-upwards sequence is explained by tidewater sedimentation during ice wastage, rapid isostatic rebound and isostatic deceleration in the late glacial. An isostatic-tectonic model comprising a forebulge on the outer continental shelf and a peripheral trough on the inner shelf is presented to resolve the apparent discrepancies between onshore and offshore sea-level data.

    AB - At Portballintrae, Northern Ireland, a well-preserved emergent facies sequence formed around 17 kyr B.P. as the Late Devensian ice sheet withdrew from the continental shelf. Three main lithofacies assemblages are recognised: (1) At the base of the sequence a massive muddy diamict was formed by resedimentation of an unstable sedimentary apron deposited in a tidewater setting. (2) Rhythmically-bedded sand and mud units contain a wide range of wave diagnostic features and are separated from the underlying diamict by both transitional and wave-eroded planar contacts. Palaeowave calculations suggest deposition in a coastal tract open to Atlantic waves. The. preservation and range of boreo-arctic foraminifera present are also typical of a lower shoreface, storm-influenced setting. (3) Interbedded gravel and sand facies are separated from the underlying rhythmically-bedded facies by a planar wave-cut surface. This facies occurs as crudely organised beds within cross-cutting, shallow scours which are associated with off-shore directed, storm-induced sediment pulses. Overall the coarsening-upwards sequence is explained by tidewater sedimentation during ice wastage, rapid isostatic rebound and isostatic deceleration in the late glacial. An isostatic-tectonic model comprising a forebulge on the outer continental shelf and a peripheral trough on the inner shelf is presented to resolve the apparent discrepancies between onshore and offshore sea-level data.

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