A radiocarbon chronology for Sanamere Lagoon, Cape York Peninsula, using multiple organic fractions

Rivera Araya, Maria, Rowe, Cassandra, Levchenko, Vladimir, Ulm, Sean, and Bird, Michael I. (2022) A radiocarbon chronology for Sanamere Lagoon, Cape York Peninsula, using multiple organic fractions. Quaternary Geochronology, 70. 101273.

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Abstract

The selection and pre-treatment of reliable organic fractions for radiocarbon age determination is fundamental to the development of accurate chronologies. Sampling from tropical lakes is particularly challenging given the adverse preservation conditions and diagenesis in these environments. Our research is the first to examine and quantify the differences between radiocarbon ages from different carbon fractions and pretreatment protocols from tropical lake sediments. Six different organic fractions (bulk organics, pollen concentrate, cellulose, stable polycyclic aromatic carbon (SPAC), macrocharcoal >250 μm and microcharcoal >63 μm) were compared at six different depths along a 1.72 m long core extracted from Sanamere Lagoon, Cape York Peninsula, northern Australia. Acid-base-acid (ABA), modified ABA (30% hydrogen peroxide + ABA), 2chlorOx (a novel cellulose pre-treatment method) and hydrogen pyrolysis (hypy) were used to pre-treat the organic fractions. The oldest date is ∼31,300 calibrated years before present (cal yr BP) and the youngest is ∼2800 cal yr BP, spanning ∼28,500 years. The smallest offset between the minimum and the maximum age for different fractions and across pretreatment methods at a given depth was found to be 832 years (between SPAC and pollen) and the largest ∼16,750 years (between pollen concentrate and SPAC). The SPAC fractions pre-treated with hypy yielded older ages compared to all other fractions in most cases, while bulk organics yielded consistently younger ages. The magnitude and consistency of the offsets and the physical and chemical properties of the tested organic fractions suggest that SPAC is the most reliable fraction to date in tropical lake sediments and that hypy successfully removes exogenous carbon contamination.

Item ID: 75784
Item Type: Article (Research - C1)
ISSN: 1878-0350
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Copyright Information: © 2022 Published by Elsevier B.V
Funders: Australian Research Council (ARC), Australian Institute of Nuclear Science and Engineering (AINSE)
Projects and Grants: ARC Laureate Fellowship (FL140100044), ARC Centre of Excellence for Australian Biodiversity and Heritage (CE170100015), AINSE Post Graduate Research Award (12357)
Date Deposited: 21 Aug 2022 23:16
FoR Codes: 37 EARTH SCIENCES > 3709 Physical geography and environmental geoscience > 370905 Quaternary environments @ 35%
37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 35%
43 HISTORY, HERITAGE AND ARCHAEOLOGY > 4301 Archaeology > 430101 Archaeological science @ 30%
SEO Codes: 13 CULTURE AND SOCIETY > 1307 Understanding past societies > 130703 Understanding Australia’s past @ 100%
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