Journal article
A chronology for Late Quaternary weathering in the Murray Basin, southeastern Australia: Evidence from 230Th/U dating of secondary uranium phosphates in the Lake Boga and Wycheproof granites, Victoria
WD Birch, SJ Mills, R Maas, JC Hellstrom
Australian Journal of Earth Sciences | TAYLOR & FRANCIS LTD | Published : 2011
Abstract
The Lake Boga Granite in northern Victoria contains a suite of well-crystallised secondary uranyl phosphates, including torbernite, salé eite, metanatroautunite and ulrichite. The minerals crystallised in miarolitic cavities and on joints, after dissolution of primary uraninite and fluorapatite by oxidising groundwater. A more restricted assemblage occurs in the nearby Wycheproof Granite. The 230Th/U dating method was used to reveal any links between formation ages of these minerals and climatic fluctuations during the Quaternary. Out of 104 analyses, 77 gave apparent ages less than about 500 ka, the upper limit beyond which secular equilibrium in the 230Th/U decay series is closely approach..
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Funding Acknowledgements
WDB acknowledges the support of the Potter Foundation for a grant to fund the analytical work. Ongoing access to the Lake Boga quarry by the operators, Mawsons, is greatly appreciated. Mineral photography is by Frank Coffa, Ben Healley and Sarah McCaffrey (all Museum Victoria). The helpful comments made by two reviewers are also acknowledged.