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Mind the gap: an absence of valley-fill deposits identifying the Holocene hypsithermal period of enhanced flow regime in southeastern Australia

Journal Article


Abstract


  • The Holocene sedimentary record in southeastern Australia is present in a range of landscape

    settings, such as upland swamps (dells), internally drained lake basins, alluvial fans, and mid-catchment

    and lowland floodplains. An assessment of the best-constrained basal radiocarbon dates in valley-fill locations

    between 30 and 42°S and upstream of last-glacial eustatic influences yields an intriguing pattern. The

    record for fluvial sites with catchment areas30km2 exhibits a distinct gap in the alluvial record between

    8 and 4 ka BP (10–4.5 ka). In contrast, data for eleven upland-swamp sites with catchment areas50km2

    exhibit a broader spectrum of basal ages, albeit with some reduction of activity during the alluvial gap.We

    suggest that the period 8–4 ka BP in the sedimentary record at the fluvial sites reflects the early to mid-

    Holocene climatic optimum independently recognized in proxy climate data in the region. It was a period

    of enhanced water discharges, stable well-vegetated catchments and low sediment yields, and therefore

    greatly limited sediment sequestration, and it has been termed the Nambucca Phase. In upland swamps,

    however, threshold-driven processes produce an episodic landscape responses during much of the Holocene.

    Contrasting results in upland compared with middle and lower basin locations demonstrate the nonuniform

    landscape response to climatic changes during the Holocene in southeastern Australia.

Publication Date


  • 2007

Citation


  • Cohen, T. J. & Nanson, G. C. (2007). Mind the gap: an absence of valley-fill deposits identifying the Holocene hypsithermal period of enhanced flow regime in southeastern Australia. The Holocene: a major interdisciplinary journal focusing on recent environmental change, 17 (3), 411-418.

Scopus Eid


  • 2-s2.0-34347376990

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/1085

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 411

End Page


  • 418

Volume


  • 17

Issue


  • 3

Abstract


  • The Holocene sedimentary record in southeastern Australia is present in a range of landscape

    settings, such as upland swamps (dells), internally drained lake basins, alluvial fans, and mid-catchment

    and lowland floodplains. An assessment of the best-constrained basal radiocarbon dates in valley-fill locations

    between 30 and 42°S and upstream of last-glacial eustatic influences yields an intriguing pattern. The

    record for fluvial sites with catchment areas30km2 exhibits a distinct gap in the alluvial record between

    8 and 4 ka BP (10–4.5 ka). In contrast, data for eleven upland-swamp sites with catchment areas50km2

    exhibit a broader spectrum of basal ages, albeit with some reduction of activity during the alluvial gap.We

    suggest that the period 8–4 ka BP in the sedimentary record at the fluvial sites reflects the early to mid-

    Holocene climatic optimum independently recognized in proxy climate data in the region. It was a period

    of enhanced water discharges, stable well-vegetated catchments and low sediment yields, and therefore

    greatly limited sediment sequestration, and it has been termed the Nambucca Phase. In upland swamps,

    however, threshold-driven processes produce an episodic landscape responses during much of the Holocene.

    Contrasting results in upland compared with middle and lower basin locations demonstrate the nonuniform

    landscape response to climatic changes during the Holocene in southeastern Australia.

Publication Date


  • 2007

Citation


  • Cohen, T. J. & Nanson, G. C. (2007). Mind the gap: an absence of valley-fill deposits identifying the Holocene hypsithermal period of enhanced flow regime in southeastern Australia. The Holocene: a major interdisciplinary journal focusing on recent environmental change, 17 (3), 411-418.

Scopus Eid


  • 2-s2.0-34347376990

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/1085

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 411

End Page


  • 418

Volume


  • 17

Issue


  • 3