Large-scale washover sedimentation in a freshwater lagoon from the southeast Australian coast: sea-level change, tsunami or exceptionally large storm?
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- Adam D. Switzer
- Department of Earth Sciences, University of Hong Kong, Hong Kong SAR, China,
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- Brian G. Jones
- School of Earth and Environmental Sciences, University of Wollongong, Wollongong NSW 2522, Australia
書誌事項
- 公開日
- 2008-08
- 権利情報
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- https://journals.sagepub.com/page/policies/text-and-data-mining-license
- DOI
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- 10.1177/0959683608089214
- 公開者
- SAGE Publications
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説明
<jats:p>A distinct lens of marine sand, up to 90 cm thick, confined vertically by peat, is found in the upper fill of a closed freshwater back-barrier lagoon on the southeast Australian coast. Coring of the deposit suggests it extends continuously up to 600 m inland and tapers landward rising to ~1.6 m above principle datum. In places the sand is overlain by accumulations of organic-rich silt that contain charophytes, indicating re-establishment of lagoon conditions. Hypotheses considered for the deposition of the sandsheet are higher Holocene sea level, storms and tsunami. Ground-penetrating radar transects of the seaward dune system suggest a penecontemporaneous erosional contact between a series of truncated pre-event dunes and several small overlying post-event dunes. Dating the sandsheet was problematic but it is confined to the last 800 years. The young age combined with a lack of associated beach deposits and evidence of wave scouring suggest that a higher sea-level hypothesis is unlikely. This sand lens is attributed to a large-scale washover event from the southeast. Based on comparisons with modern storm deposits from the same coast and sedimentological diagnostic criteria derived from studies of modern storm- and tsunami-deposited sandsheets, it is concluded that this sand deposit is the product of a short-lived, large-scale overwash event attributed to a late-Holocene tsunami.</jats:p>
収録刊行物
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- The Holocene
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The Holocene 18 (5), 787-803, 2008-08
SAGE Publications