117-13 25 Years of Field Study at Acid Salt Lakes in Western Australia: Why Visiting a Salt Lake Once or Twice is Not Enough

Abstract:

Ephemeral acid salt lakes on the Yilgarn Craton of southern Western Australia are both spatially and temporally dynamic. Here, we share field observations of the changes in sedimentology , mineralogy, and water geochemistry that we’ve documented over multiple time scales from 10 field campaigns between 2001 and 2026, with a focus on five lakes near Hyden, Norseman, and Salmon Gums. 

Atmospheric conditions play a significant role in the state of a lake at any one time. Specific pHs, salinities, and temperatures are not sufficient to predict exact minerals and sedimentary features.  We have found different products in the same places at different times under the same geochemical conditions.

A long-held question about the rate of growth of bottom-growth gypsum was addressed with new field observations made in January 2015, January 2026, mid-March 2026, and late March 2026. We estimate that bottom-growth gypsum crystals, many of which are swallowtails, may grow faster than 5 mm/yr.

We propose that a single visit to an ephemeral acid salt only gives a snapshot of the range of potential geochemistry, mineralogy, and sedimentary processes and products.  Understanding these extreme environments and their Earth system interactions requires multiple field campaigns that capture various time ranges, including hours, days, months, seasons, years, and decades.

Geological Society of America Abstracts with Programs. Vol. 58, No. 5, 2026

doi: 10.1130/abs/2026AM-19850

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.