Authors / CoAuthors
Clarke, J.D.A. | Brodie, R.S. | Norman, R. | Magee, J.W.
Abstract
Sonic drilling is a relatively new technology that has been used successfully to obtain relatively uncontaminated and undisturbed continuous core samples with excellent recovery rates to depths of 206m in fluvio-lacustrine sediments of the Darling River floodplain in western NSW. However, there are limitations with the method. Sands, in particular, are disturbed when they are vibrated out of the core barrel into the flexible plastic sampling tube. There can be changes to moisture content, pore fluid chemistry and sediment mineralogy on exposure to the atmosphere, even when the samples are processed and analysed soon after collection. The option exists during drilling to encapsulate the core in rigid polycarbonate lexan tubes. Although this increases costs and reduces drilling rates, atmospheric exposure of the core during drilling is reduced to the ends of the lexan tubes before being capped. In addition, the tubes can be purged with an inert gas such as argon. Lexan coring is best carried out below the watertable as the heat from drilling dry clays can cause the polycarbonate to melt. In this study, lexan-encapsulated core samples were obtained for analysis of pore fluids (salinity, major ions, trace metals, stable isotopes) and mineral phases (XRD, XRF). The major advantage was the recovery of encapsulated and intact sediment intervals for determining hydraulic conductivity by centrifuge or falling head permeameter methods. By painting some tubes black, sand samples were also successfully obtained for optically stimulated luminescence (OSL) dating. Alternatively, opaque black lexan can be made to order by the supplier.
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nonGeographicDataset
eCat Id
73638
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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Keywords
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- GA PublicationAbstract
- ( Theme )
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- hydrogeology
- ( Theme )
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- groundwater
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2012-02-15T00:00:00
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geoscientificInformation
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[-33.159278, -31.814781, 141.958071, 143.284724]
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