This is an inverse distance weighted interpolation showing how many times the K/Cl ratio value is above the seawater mean K/Cl value, derived from the CSIRO WASANT hydrogeochemistry. Areas in yellow to red indicate a higher value.

The purpose of the potash IDW rasters is to better highlight broader patterns in the CSIRO WASANT hydrogeochemistry that are not as readily apparent in the neighbourhood statistics rasters. An example is the observable divide between the north and south Yilgarn roughly along the 30º south parallel. This is known as the Menzies line and represents a climatological variation in rainfall amount, seasonality and evaporation rates (Anand and Butt, 2010; Mernagh, 2013).

Caution is advised when using these IDW rasters as they are only intended for a broad overview. Each controlling data point (i.e. hydrogeochemical sample point) was assigned a radius of influence of 0.5º (lat./long.) or roughly 50 kilometres. Thus an outlying data point could control the raster value for an area approximately 8000 to 10 000 square kilometres. As such, the raster values in areas with sparse data points should be used with great caution.

Stretched

Colour ramp: 28 rainbow_bgyr_35-85_c73 (CET Perceptually Uniform Colour Maps (colorcet.com)); low: 0.0025 – high: 87.5000

Histogram Equalize stretch

Hydrogeochemistry--CSIRO WASANT

Anand, RR and Butt, CRM 2010, A guide for mineral exploration through the regolith in the Yilgarn Craton, Western Australia: Australian Journal of Earth Sciences, v. 57, p. 1015–1114.

Mernagh, TP (editor) 2013, A review of Australian salt lakes and assessment of their potential for strategic resources: Geoscience Australia, Record 2013/39, 243p.