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Identification of a penultimate interglacial (marine isotope stage 7) alluvium in South Australia and its climatic and sea-level implications

Journal Article


Abstract


  • Alluvial sequences proximal to coastlines offer opportunities to establish associations between terrestrial, sea-level and climatic events. South Australia hosts a globally significant Pleistocene interglacial sea-level record and numerous terrestrial sediment sources. However, only fragmentary evidence of pre-Last Interglacial alluvium has been identified. This paper presents the first definitive recognition of MIS 7 alluvium in South Australia, which occurs beneath the surface of extensive river terraces flanking Currency Creek and the Finniss River, between the Mount Lofty Ranges and the River Murray Lakes. A thermoluminescence age, 227 ± 24 ka, correlates with the penultimate interglacial global sea-level highstand. Nearby, last interglacial fossils of the estuarine bivalve Spisula trigonella at 2.53 ± 0.25 m APSL occupy a hollow eroded into the MIS 7 alluvium. Increasing aridity and decreased fluvial activity in the late Quaternary have preserved the MIS 7 alluvium. The fragmentary record of alluvium pre-dating the Last Interglacial is attributed to three principal causes: (1) tectonic subsidence of the Murray Estuary, which increased the potential for burial or coastal erosion of sediments; (2) erosion and reworking of previously existing alluviums, especially during low sea levels of glacial times; (3) the absence of reliable dating controls on the potentially older alluvial sediments.

Publication Date


  • 2018

Citation


  • Ryan, D. D., Bourman, R. P., Price, D. M. & Murray-Wallace, C. V. (2018). Identification of a penultimate interglacial (marine isotope stage 7) alluvium in South Australia and its climatic and sea-level implications. Transactions of the Royal Society of South Australia, 142 (2), 208-223.

Scopus Eid


  • 2-s2.0-85052321623

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers1/161

Number Of Pages


  • 15

Start Page


  • 208

End Page


  • 223

Volume


  • 142

Issue


  • 2

Place Of Publication


  • Australia

Abstract


  • Alluvial sequences proximal to coastlines offer opportunities to establish associations between terrestrial, sea-level and climatic events. South Australia hosts a globally significant Pleistocene interglacial sea-level record and numerous terrestrial sediment sources. However, only fragmentary evidence of pre-Last Interglacial alluvium has been identified. This paper presents the first definitive recognition of MIS 7 alluvium in South Australia, which occurs beneath the surface of extensive river terraces flanking Currency Creek and the Finniss River, between the Mount Lofty Ranges and the River Murray Lakes. A thermoluminescence age, 227 ± 24 ka, correlates with the penultimate interglacial global sea-level highstand. Nearby, last interglacial fossils of the estuarine bivalve Spisula trigonella at 2.53 ± 0.25 m APSL occupy a hollow eroded into the MIS 7 alluvium. Increasing aridity and decreased fluvial activity in the late Quaternary have preserved the MIS 7 alluvium. The fragmentary record of alluvium pre-dating the Last Interglacial is attributed to three principal causes: (1) tectonic subsidence of the Murray Estuary, which increased the potential for burial or coastal erosion of sediments; (2) erosion and reworking of previously existing alluviums, especially during low sea levels of glacial times; (3) the absence of reliable dating controls on the potentially older alluvial sediments.

Publication Date


  • 2018

Citation


  • Ryan, D. D., Bourman, R. P., Price, D. M. & Murray-Wallace, C. V. (2018). Identification of a penultimate interglacial (marine isotope stage 7) alluvium in South Australia and its climatic and sea-level implications. Transactions of the Royal Society of South Australia, 142 (2), 208-223.

Scopus Eid


  • 2-s2.0-85052321623

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers1/161

Number Of Pages


  • 15

Start Page


  • 208

End Page


  • 223

Volume


  • 142

Issue


  • 2

Place Of Publication


  • Australia