What is this layer?
MnO/Fe2O3T content for all sample media included in the GSWA near-surface geochemistry datasets. This statewide dataset includes information from WACHEM, OZCHEM (the WA subset), CRCLEME-laterite and WAMEX (surface rock chip, stream, soil and shallow drillhole).
The MnO/Fe2O3T index demonstrates areas where MnO has been enriched relative to total Fe2O3. This index is a proxy oxidation, where a higher ratio indicates increased likelihood that the rock experienced high degrees of oxidation and enrichment in MnO.
A unique legend and colour scheme has been chosen for this geochemical layer to best highlight geochemical trends, via a 3 × 3 cell mean neighbourhood statistics raster. Cell resolution is 0.05º (~5 km). Areas in red indicate a higher value.
The use of this ratio ‘normalizes’ disparate primary data sets obtained from different sample media using a variety of laboratory methods, allowing their combination and comparison. Even so, all these indices will be sensitive to precursor rock chemistry and to the effects of overprinting events, such as weathering. These factors need to be taken into consideration when interpreting alteration indices.