Title

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

RIS ID

129863

Publication Details

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, Online First 1-16.

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.

This record is in the process of being updated. Please contact us for more information.

Share

COinS
 

Link to publisher version (DOI)

http://dx.doi.org/10.1080/03721426.2018.1509415