Abstract
The Earth’s surface comprises minerals diagnostic of weathering, deposition and erosion. The first continental-scale mineral maps generated from an imaging satellite with spectral bands designed to measure clays, quartz and other minerals were released in 2012 for Australia. Here we show how these satellite mineral maps improve our understanding of weathering, erosional and depositional processes in the context of changing weather, climate and tectonics. The clay composition map shows how kaolinite has developed over tectonically stable continental crust in response to deep weathering during northwardly migrating tropical conditions from 45 to 10 Ma. The same clay composition map, in combination with one sensitive to water content, enables the discrimination of illite from montmorillonite clays that typically develop in large depositional environments over thin (sinking) continental crust such as the Lake Eyre Basin. Cutting across these clay patterns are sandy deserts that developed <10 Ma and are well mapped using another satellite product sensitive to the particle size of silicate minerals. This product can also be used to measure temporal gains/losses of surface clay caused by periodic wind erosion (dust) and rainfall inundation (flood) events. The accuracy and information content of these satellite mineral maps are validated using published data.
Highlights
Australia is a flat, dry, deeply weathered continent reflecting its low rates of erosion and long-lived tectonic stability associated with its mosaic of Precambrian blocks[1]
This paper focuses on three of the available seventeen published ASTER geoscience maps[30] plus introduces a new one designed for measuring water content and/or particle size
The National Geochemical Survey of Australia (NGSA) is a public suite of physicochemical data (LOI, major/ minor/trace element geochemistry and particle size) measured from unconsolidated, flood-overbank samples collected at 0–10 cm and ~60–80 cm depths from over 1000 river catchments across Australia[32,33,34]
Summary
Dry, deeply weathered continent reflecting its low rates of erosion and long-lived tectonic stability associated with its mosaic of Precambrian blocks[1]. This paper focuses on three of the available seventeen published ASTER geoscience maps[30] plus introduces a new one designed for measuring water content and/or particle size (see Methods) These four ASTER SWIR and TIR mineral products focus on clay, water, quartz and particle size information and are validated using published field sample data as well as meteorological, geophysical and other satellite data. Their value for mapping and monitoring the effects of weathering, erosion and deposition in the context of variable vegetation cover, climate and tectonic processes is assessed before a final perspective on the future of mineral mapping and monitoring of the Earth using integrated (VNIR-) SWIR-TIR imaging systems is outlined
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