Authors / CoAuthors
Wilford, J. | de Caritat, P. | Bui, E.N.
Abstract
Regolith carbonate or secondary carbonate is a key component of the regolith, particularly in many Mediterranean, arid and semi-arid regions of Australia. National maps of regolith carbonate distribution have been compiled from regional soil, regolith and geological mapping with varying degrees of confidence and consistency. Here we apply a decision tree approach based on a piecewise linear regression model to estimate and map the near-surface regolith carbonate concentration at the continental scale. The model is based on relationships established from the 1311 field sites of the National Geochemical Survey of Australia (NGSA) and 49 national environmental covariate datasets. Regolith carbonate concentration (weight %) was averaged from the <2 mm grain size-fractions of samples taken from two depth ranges (0-10 cm and ~60-80 cm) at each NGSA site. The final model is based on the average of 20 runs generated by randomly selecting 90% training and 10% validation splits of the input data. Results present an average coefficient of determination (R2) of 0.56 on the validation dataset. The covariates used in the prediction are consistent with our understanding of the controls on the sources (inputs), preservation and distribution of regolith carbonate within the Australian landscape. The model produces a continuous, quantitative prediction of regolith carbonate abundance in surficial regolith at a resolution of 90 m with associated estimates of model uncertainty. The model-derived map is broadly consistent with our current knowledge of the distribution of carbonate-rich soil and regolith in Australia. This methodology allows the rapid generation of an internally consistent and continuous layer of geoinformation that may be applicable to other carbonate-rich landscapes globally. The methodology used in this study has the potential to be used in predicting other geochemical constituents of the regolith.
Product Type
nonGeographicDataset
eCat Id
76338
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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- External PublicationAbstract
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- AU
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Geochemistry
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- Published_Internal
Publication Date
2013-01-01T00:00:00
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geoscientificInformation
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National Geochemical Survey of Australia (NGSA)
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[-44.0, -10.0, 112.0, 154.0]
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National Geochemical Survey of Australia (NGSA) 112.0 154.0 -44.0 -10.0 N/A