Mineralogy of acid saline lake systems in Southern Western Australia

Southern Western Australia (WA) hosts a combination of Archean bedrock, Tertiary and younger sediments, and modern ephemeral lacustrine environments. What makes it unique is the extreme regional groundwater and lake water chemistry, much of which is acidic. The work presented here is part of a larger research project that began in 2001 with the goal of characterizing the evolution of acid groundwater and lake water in WA. In order to address this goal, I used a three part approach that focused on the mineralogical variability associated with the extreme chemistry of three acid saline lakes and one alkaline lake. The first part of my research identified and described unique authigenic mineral assemblages characteristic of surface deposits associated with two acid saline lakes, Twin Lakes and Lake Aerodrome. The second prong of my approach focused on identifying these unique mineral assemblages at depth and distinguishing them from the original mineralogy of sediments at depth below Lake Aerodrome. The final prong of my approach worked from the bottom up, focusing on the relationship between bedrock weathering and lake water chemistry at Prado Lake (acid) and Gastropod Lake (alkaline). Overall, I found that the extreme chemistry of these lakes does produce unique mineral assemblages that are identifiable at depth and that the extent of bedrock weathering may play a significant role in the acidity of the lake water.