Many years ago, I used to work as a gold exploration geologist. One of the main locations was a salt lake in Western Australia detailed in the document WMC Resources Exploration Successes inN Lake Terrains - Applications of Element Dispersion, Kambalda W.A (Carey and Dusci, 1993).

In the article, and in my research at the time, it is stated that

gold disperses laterally along iron redox fronts that tend to occur higher in the regolith profile

Now the area is arid (up to 50C or 122F in summer), but was not always like this, fossil records suggest far milder conditions occurred in the past.

My question is, how does the ambient temperature affect the rate of redox reaction in a salt lake, such as in the example provided?


The salt lakes that occur in Western Australia are touted by the article Geochemical characteristics of naturally acid and alkaline saline lakes in southern Western Australia (Bowen and Benison, 2009) are unique environments, in that they possess

an extreme and rare range of natural hydrogeochemical conditions. Many WA lake waters and groundwaters are hypersaline and acidic.

The article discusses observations of effects due to temperature, especially cycles of dry and wet. The high ambient temperatures would cause increased evaporation, and hence increase local evapoconcentrations of ions, resulting in a lowering of the local pH, storm/inundation events have the opposite effect. This leads to further observations by the authors that found that

Field observations of lake pH during storm events illustrated that fluids that have been freshened due to meteoric input are able to regain acidity rapidly. Part of the acidity may be locally sustained by ongoing $\ce{Fe}$ cycling and redox reactions that generate $\ce{H+}$ ions. The amount of $\ce{Fe}$ increases significantly in the more acid waters, and authigenic $\ce{Fe} mineralization (oxides and sulfates, e.g., hematite and jarosite) is abundant throughout the acid lake sediments.


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