U-series dating of soda straw stalactites from excavated deposits: method development and application to Blanche Cave, Naracoorte, South Australia

This study aimed to further test the method, reported by St Pierre et al. (2009), to develop robust chronologies of deposits in limestone caves through U/Th (Uranium/Thorium or U-Series) dating of soda straw stalactites. The chronology of fossil bearing deposits at Blanche Cave was further constrain...

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Bibliographic Details
Published in:Journal of archaeological science 2012-04, Vol.39 (4), p.922-930
Main Authors: St Pierre, Emma, Zhao, Jian-xin, Feng, Yue-xing, Reed, Elizabeth
Format: Article
Language:English
Subjects:
Blanche Cave
Earth sciences
Earth, ocean, space
Exact sciences and technology
Geochronology
Isotope geochemistry. Geochronology
Limestone cave and rockshelter sites
Marine and continental quaternary
Naracoorte South Australia
Quaternary chronology
Soda straw stalactites
Speleothems
Surficial geology
U/Th dating
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Summary:This study aimed to further test the method, reported by St Pierre et al. (2009), to develop robust chronologies of deposits in limestone caves through U/Th (Uranium/Thorium or U-Series) dating of soda straw stalactites. The chronology of fossil bearing deposits at Blanche Cave was further constrained with thermal ionisation mass spectrometry (TIMS) U/Th dating of 17 additional soda straw stalactite samples, and results were compared to recalibrated 14C ages of charcoal. The results support the assertion that soda straw stalactites can provide ages close to the time of sediment deposition and may be used as reliable chronological markers, particularly for periods reaching or beyond the radiocarbon dating limit. The application of an enhanced cleaning technique facilitated the reduction of detrital Th in samples, significantly increasing age accuracy and precision. Additionally U/Th age accuracy and precision was increased through the application of site-specific measured U/Th ratios to correct for the detrital 230Th component in samples. ► Enhanced cleaning increased U/Th age accuracy and precision. ► Site-specific Th/U ratios increased age accuracy and precision. ► Soda straw stalactites can be used to accurately date deposits in limestone caves.
ISSN:0305-4403
1095-9238
DOI:10.1016/j.jas.2011.10.027