142-6 Ephemeral Saline Lake Systems as Analogs for Martian Crater Lakes: Insights from Shoemaker Crater, Western Australia

Session: Geomorphology and Landscape Evolution of Mars (Posters)

Poster Booth No.: 328

Presenting Author:

Natasha Tagle

Authors:

Tagle, Natasha B.¹, Kah, Linda C.², Bartley, Julie K.³, Schmoyer, Sonja M.⁴, Sumrall, Colin D.⁵

(1) Earth, Environmental, and Planetary Sciences, University of Tennessee, Knoxville, Tennessee, USA, (2) Earth, Environmental and Planetary Sciences, University of Tennessee, Knoxville, TN, , (3) Gustavus Adolphus College, Saint Peter, MN, , (4) Earth, Environmental and Planetary Sciences, University of Tennessee, Knoxville, TN, , (5) Earth, Environmental and Planetary Sciences, University of Tennessee, Knoxville, TN, ,

Abstract:

Crater lakes are prime targets in the search for ancient Martian habitability, yet they are often modeled as single, long-lived evaporative basins producing concentric “bullseye” mineral zonation and thick deposits of evaporative facies. Facies relationships in Gale crater, Mars, for instance, show a more complex history of lacustrine, aeolian, and diagenetically overprinted deposits indicative of episodic flooding, evaporation, and groundwater interaction rather than simple basin-wide desiccation. 

Reconstructing this dynamic depositional and diagenetic history requires a terrestrial analog that captures comparable hydrologic complexity. Shoemaker crater, Western Australia, is a ~25 km diameter, Fe-rich and sulfur-bearing impact crater that hosts multiple ephemeral saline lakes. These lakes develop prominent color variation during drying, precipitate gypsum and halite, and are surrounded by gypsiferous soils reflecting mixed lake/groundwater contributions. However, these systems remain essentially undocumented. We will be addressing this gap in understanding by (1) characterizing the geochemical evolution of Shoemaker’s lakes across wet and dry seasons and (2) documenting spatial and temporal variability in lacustrine sedimentary fabrics and facies across the basin.

Here, we report on lake behavior based on multi-year surveys of LANDSAT images and show results from our initial field season in mid-May to early-June 2026. Comparison of LANDSAT images to regional rainfall shows a complex relationship between input fluids and longer-term lake behavior. Initial in situ reconnaissance of dried lakes shows a range of characteristics, with the lakes on the crater rim displaying a hardened, mud cracked surface and little evidence for evaporite deposition at the surface. By contrast, other lakes record a variably soft surface of generally uniform efflorescent halite salts, with regions of depressed topography marked by a gypsum crust. Trenching of the lakes and their inlet channels showed gypsum precipitating in sediment pores in upper subsurface, displacive lensoidal gypsum above the water table, and groundwater present at about 30-40 cm depth. We suggest the ephemeral saline lakes within Shoemaker crater—which preserve evidence of wet-dry hydrologic variability in their evaporite mineralogy and sediment fabrics—may serve as a useful analog for episodic, groundwater-influenced lake systems proposed for Gale crater’s sulfate-bearing units.

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