A major challenge that bedrock mineral exploration faces in many parts of South Australia is exploring efficiently and effectively through extensive and thick cover. The Coompana regolith map aims to provide a broad-scale framework for guiding...

A major challenge that bedrock mineral exploration faces in many parts of South Australia is exploring efficiently and effectively through extensive and thick cover. The Coompana regolith map aims to provide a broad-scale framework for guiding surface geochemical prospecting for a wide range of minerals and materials, as a basis for guiding mineral exploration, and to provide a useful dataset for addressing other land use issues like groundwater.

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Mapping was based on the 1:250,000-scale geological map series using the RTMAP (Regolith-Terrain MAP) scheme, which had to be adjusted and revised for South Australia's regolith conditions. The regolith polygon linework was newly compiled for 68...

Mapping was based on the 1:250,000-scale geological map series using the RTMAP (Regolith-Terrain MAP) scheme, which had to be adjusted and revised for South Australia's regolith conditions. The regolith polygon linework was newly compiled for 68 1:250,000 scale mapsheets using ArcGIS 9.3. For each regolith polygon ten attributes were captured during the mapping process including regolith materials and landforms name, description, RTMAP code and map symbol, as well as the TI (transported or in-situ) and RED (residual-erosional-depositional) scheme. Mapping and map compilation was based on a variety of data, with the 1:100,000 and 1:2,000,000 State geology datasets, Landsat TM5 and ETM7 images, 1sec and 3sec DEM, radiometrics, Google Earth (3D view) and existing CRCLEME regolith maps for South Australia representing the key datasets. Spatial accuracy and linework detail was improved in comparison to the 1:2,000,000 State geology dataset, due to the availability of higher resolution images. This also makes the linework of the digital regolith dataset usable at scales finer than 1:2,000,000. It should be noted that the South Australian regolith map represents the surface distribution and expression of the regolith and it does not include any information about regolith thickness, stratigraphy and age. No in-situ regolith profile nomenclature has been applied (including saprolith, saprock, saprolite and pedolith). Very limited information about bedrock weathering intensity was available from existing datasets. Therefore, outcropping bedrocks undifferentiated by geological province, lithology and stratigraphy have been subdivided into two map units: fresh to moderately weathered bedrock and moderately to highly weathered bedrock. Material that has a close association with the underlying bedrock and has not experienced a large degree of transport has been mapped as residual material.
Positional accuracy:Nominal scale 1:2,000,000 highly variable since the map was digitised at various scales between 1:50,000 and 1:250,000.
Attribute accuracy:Variable due to regolith attributes being derived from geological and regolith mapping work done by a series of authors based on the 1:250,000-scale geological map series, complemented by the 1:2,000,000 State Geology Map and existing information from various datasets such as 1:100,000 geology, topographic, geophysical and multispectal and hyperspectral remote sensing data. 

The attributes were assessed against current regolith science mapping codes and authority tables and were modified and standardised with current information.
Logical consistency: Most of the information is derived from pre-existing digital data, and interpretations based on the personal experience or judgement by the authors and other Geological Survey of South Australia geoscientists have been used where data were unavailable. Several geoscientists visually inspected the finished dataset to make sure the attributes were accurate and the data were consistent spatially with current scientific information.
Completeness:Complete for South Australia, subject to update.

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