Chronostratigraphy of a 270-ka sediment record from Lake Selina, Tasmania: Combining radiometric, geomagnetic and climatic dating
Date
2021-03
Authors
Lise-Pronovost, Agathe
Fletcher, Michael-Shawn
Simon, Quentin
Jacobs, Zenobia
Gadd, Patricia S
Heslop, David
Herries, Andy I R
Yokoyama, Yusuke
Aster team
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Elsevier
Abstract
Lake sediment archives covering several glacial cycles are scarce in the Southern Hemisphere and they are challenging to date. Here we present the chronostratigraphy of the oldest continuous lake sediment archive in Tasmania, Australia; a 5.5 m and 270 ka (Marine Isotope Stage 8) sediment core from Lake Selina. We employ radiometric dating (radiocarbon and optically stimulated luminescence) and relative dating (geomagnetic and climate comparisons). Bayesian modeling of the radiometric ages reaches back to 80 ka (1.7 m) and relative dating using a dynamic programing algorithm allows dating of the full sequence. Elemental data, magnetic properties and beryllium isotopes from Lake Selina reveal a close fit to Antarctic ice core climate proxies. Weaker correlation during the Last Glacial Period (MIS 2–4) is attributed to additional local factors impacting Lake Selina proxies at a time of climate changes and human arrival into Tasmania. Over that period, full vector paleomagnetic records and authigenic 10Be/9Be ratios are combined to identify the Laschamp geomagnetic excursion for the first time in Australia and constrain the chronology. The multi-method approach provides two preferred age models, indiscernible within their uncertainties, which allows the use of a geomagnetic dipole-independent (full archive) or a climate-independent (111 ka to present) age model.
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Keywords
Paleomagnetism, Optically stimulated luminescence, Radiocarbon, Authigenic 10Be/9Be ratio, Pleistocene, Lake sediment, Australia
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Source
Quaternary Geochronology
Type
Journal article
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2099-12-31
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