AMS C-14 dating of deglacial events in the Irish Sea Basin and other sectors of the British-Irish ice sheet

AM McCabe, PU Clark, J Clark

    Research output: Contribution to journalArticle

    75 Citations (Scopus)

    Abstract

    Sedimentary sequences deposited by the decaying marine margin of the British-Irish Ice Sheet (BIIS) record isostatic depression and successive ice sheet retreat towards centres of ice dispersion. Radiocarbon dating by accelerator mass spectrometry (AMS) of in situ marine microfaunas that are commonly associated with these sequences constrain the timing of glacial and sea level fluctuations during the last deglaciation, enabling us to evaluate the dynamics of the BUS and its response to North Atlantic climate change. Here we use our radiocarbon-dated stratigraphy to define six major glacial and sea level events since the Last Glacial Maximum. (1) Initial deglaciation may have occurred >= 18.3 kyr C-14 BP along the northwestern Irish coast, in agreement with a deglacial age of similar to 22 Cl-36 kyr BP for southwestern Ireland. Ice retreated to inland centres and areas of transverse moraine began to form across the north Irish lowlands. (2) Channels cut into glaciomarine deglacial sediments along the western Irish Sea coast are graded to below present sea level, identifying a fall of relative sea level (RSL) in response to isostatic emergence of the coast. (3) Marine mud that rapidly infilled these channels records an abrupt rise in global sea level of 10-15 m similar to 16.7 C-14 kyr BP that flooded the Irish Sea coast and may have triggered deglaciation of a marine-based margin in Donegal Bay. (4) Intertidal boulder pavements in Dundalk Bay indicate that RSL similar to 15.0 C-14 kyr BP was similar to present. (5) A major readvance of all sectors of the BIIS occurred between 14 and 15 kyr (14) C BP which overprinted subglacial transverse moraines and delivered a substantial sediment flux to tidewater ice sheet margins. This event, the Killard Point Stadial, indicates that the BUS participated in Heinrich event 1. (6) Subsequent deposition of marine muds on drumlins 12.7 C-14 kyr BP indicates isostatic depression and attendant high RSL resulting from the Killard Point readvance. These events identify a dynamic BIIS during the last deglaciation, as well as significant changes in RSL that reflect a combination of isostatic loading and eustatic changes in global sea level. (c) 2005 Elsevier Ltd. All rights reserved.
    LanguageEnglish
    Pages1673-1690
    JournalQuaternary Science Reviews
    Volume24
    Issue number14-15
    DOIs
    Publication statusPublished - Aug 2005

    Fingerprint

    accelerator mass spectrometry
    ice sheet
    sea level
    basin
    last deglaciation
    coast
    deglaciation
    mud
    glaciomarine deposit
    ice
    drumlin
    dating
    sea
    Heinrich event
    radiocarbon dating
    moraine
    boulder
    sedimentary sequence
    pavement
    Last Glacial Maximum

    Cite this

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    title = "AMS C-14 dating of deglacial events in the Irish Sea Basin and other sectors of the British-Irish ice sheet",
    abstract = "Sedimentary sequences deposited by the decaying marine margin of the British-Irish Ice Sheet (BIIS) record isostatic depression and successive ice sheet retreat towards centres of ice dispersion. Radiocarbon dating by accelerator mass spectrometry (AMS) of in situ marine microfaunas that are commonly associated with these sequences constrain the timing of glacial and sea level fluctuations during the last deglaciation, enabling us to evaluate the dynamics of the BUS and its response to North Atlantic climate change. Here we use our radiocarbon-dated stratigraphy to define six major glacial and sea level events since the Last Glacial Maximum. (1) Initial deglaciation may have occurred >= 18.3 kyr C-14 BP along the northwestern Irish coast, in agreement with a deglacial age of similar to 22 Cl-36 kyr BP for southwestern Ireland. Ice retreated to inland centres and areas of transverse moraine began to form across the north Irish lowlands. (2) Channels cut into glaciomarine deglacial sediments along the western Irish Sea coast are graded to below present sea level, identifying a fall of relative sea level (RSL) in response to isostatic emergence of the coast. (3) Marine mud that rapidly infilled these channels records an abrupt rise in global sea level of 10-15 m similar to 16.7 C-14 kyr BP that flooded the Irish Sea coast and may have triggered deglaciation of a marine-based margin in Donegal Bay. (4) Intertidal boulder pavements in Dundalk Bay indicate that RSL similar to 15.0 C-14 kyr BP was similar to present. (5) A major readvance of all sectors of the BIIS occurred between 14 and 15 kyr (14) C BP which overprinted subglacial transverse moraines and delivered a substantial sediment flux to tidewater ice sheet margins. This event, the Killard Point Stadial, indicates that the BUS participated in Heinrich event 1. (6) Subsequent deposition of marine muds on drumlins 12.7 C-14 kyr BP indicates isostatic depression and attendant high RSL resulting from the Killard Point readvance. These events identify a dynamic BIIS during the last deglaciation, as well as significant changes in RSL that reflect a combination of isostatic loading and eustatic changes in global sea level. (c) 2005 Elsevier Ltd. All rights reserved.",
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    AMS C-14 dating of deglacial events in the Irish Sea Basin and other sectors of the British-Irish ice sheet. / McCabe, AM; Clark, PU; Clark, J.

    In: Quaternary Science Reviews, Vol. 24, No. 14-15, 08.2005, p. 1673-1690.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - AMS C-14 dating of deglacial events in the Irish Sea Basin and other sectors of the British-Irish ice sheet

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    AU - Clark, PU

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    N2 - Sedimentary sequences deposited by the decaying marine margin of the British-Irish Ice Sheet (BIIS) record isostatic depression and successive ice sheet retreat towards centres of ice dispersion. Radiocarbon dating by accelerator mass spectrometry (AMS) of in situ marine microfaunas that are commonly associated with these sequences constrain the timing of glacial and sea level fluctuations during the last deglaciation, enabling us to evaluate the dynamics of the BUS and its response to North Atlantic climate change. Here we use our radiocarbon-dated stratigraphy to define six major glacial and sea level events since the Last Glacial Maximum. (1) Initial deglaciation may have occurred >= 18.3 kyr C-14 BP along the northwestern Irish coast, in agreement with a deglacial age of similar to 22 Cl-36 kyr BP for southwestern Ireland. Ice retreated to inland centres and areas of transverse moraine began to form across the north Irish lowlands. (2) Channels cut into glaciomarine deglacial sediments along the western Irish Sea coast are graded to below present sea level, identifying a fall of relative sea level (RSL) in response to isostatic emergence of the coast. (3) Marine mud that rapidly infilled these channels records an abrupt rise in global sea level of 10-15 m similar to 16.7 C-14 kyr BP that flooded the Irish Sea coast and may have triggered deglaciation of a marine-based margin in Donegal Bay. (4) Intertidal boulder pavements in Dundalk Bay indicate that RSL similar to 15.0 C-14 kyr BP was similar to present. (5) A major readvance of all sectors of the BIIS occurred between 14 and 15 kyr (14) C BP which overprinted subglacial transverse moraines and delivered a substantial sediment flux to tidewater ice sheet margins. This event, the Killard Point Stadial, indicates that the BUS participated in Heinrich event 1. (6) Subsequent deposition of marine muds on drumlins 12.7 C-14 kyr BP indicates isostatic depression and attendant high RSL resulting from the Killard Point readvance. These events identify a dynamic BIIS during the last deglaciation, as well as significant changes in RSL that reflect a combination of isostatic loading and eustatic changes in global sea level. (c) 2005 Elsevier Ltd. All rights reserved.

    AB - Sedimentary sequences deposited by the decaying marine margin of the British-Irish Ice Sheet (BIIS) record isostatic depression and successive ice sheet retreat towards centres of ice dispersion. Radiocarbon dating by accelerator mass spectrometry (AMS) of in situ marine microfaunas that are commonly associated with these sequences constrain the timing of glacial and sea level fluctuations during the last deglaciation, enabling us to evaluate the dynamics of the BUS and its response to North Atlantic climate change. Here we use our radiocarbon-dated stratigraphy to define six major glacial and sea level events since the Last Glacial Maximum. (1) Initial deglaciation may have occurred >= 18.3 kyr C-14 BP along the northwestern Irish coast, in agreement with a deglacial age of similar to 22 Cl-36 kyr BP for southwestern Ireland. Ice retreated to inland centres and areas of transverse moraine began to form across the north Irish lowlands. (2) Channels cut into glaciomarine deglacial sediments along the western Irish Sea coast are graded to below present sea level, identifying a fall of relative sea level (RSL) in response to isostatic emergence of the coast. (3) Marine mud that rapidly infilled these channels records an abrupt rise in global sea level of 10-15 m similar to 16.7 C-14 kyr BP that flooded the Irish Sea coast and may have triggered deglaciation of a marine-based margin in Donegal Bay. (4) Intertidal boulder pavements in Dundalk Bay indicate that RSL similar to 15.0 C-14 kyr BP was similar to present. (5) A major readvance of all sectors of the BIIS occurred between 14 and 15 kyr (14) C BP which overprinted subglacial transverse moraines and delivered a substantial sediment flux to tidewater ice sheet margins. This event, the Killard Point Stadial, indicates that the BUS participated in Heinrich event 1. (6) Subsequent deposition of marine muds on drumlins 12.7 C-14 kyr BP indicates isostatic depression and attendant high RSL resulting from the Killard Point readvance. These events identify a dynamic BIIS during the last deglaciation, as well as significant changes in RSL that reflect a combination of isostatic loading and eustatic changes in global sea level. (c) 2005 Elsevier Ltd. All rights reserved.

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