10-15 Controls on Near-Surface Water Movement across Linear Dunes and Claypans Located in Interdune Swales

Session: Undergraduate and Graduate Geoscience Student Showcase (Posters)

Poster Booth No.: 72

Presenting Author:

Kaleigh Mattes

Authors:

Mattes, Kaleigh M.¹, Hoy, Ethan², Rotz, Rachel R.³, Craddock, Robert A.⁴, MacDonald, James H.⁵, Craddock, Maxwell L⁶, Kling, Corbin⁷

(1) Environmental Geology Program, Florida Gulf Coast University, Fort Myers, Florida, USA, (2) Environmental Geology Program, Florida Gulf Coast University, Fort Myers, Florida, USA, (3) Florida Gulf Coast University, Fort Myers, FL, USA, (4) Smithsonian Institution, Washington, DC, USA, (5) Florida Gulf Coast University, Fort Myers, FL, USA, (6) Earth-Life Science Institute (ELSI), Institute of Science, Tokyo, Japan, (7) Planet Labs, San Francisco, CA, USA,

Abstract:

The Simpson Desert of central Australia is a terrestrial analog for planetary dune systems, where linear dunes and claypans located in interdune swales exert controls on transient water retention under arid conditions. This study investigates how sedimentological and mineralogical characteristics vary by dune position (crest, flank, swale, and claypan) and how these variations influence water infiltration and water–sediment interactions within dune systems. Field-saturated hydraulic conductivity (Kfs) tests were conducted at 21 dune locations, and co-located sediment samples were collected for grain-size analysis using a Malvern Particle Size Analyzer. Mineralogical composition was determined using powder X-ray diffraction (PXRD), complemented by thin section petrography to assess grain texture, sorting, and packing. Results show that Kfs decreases systematically from crests (2.2 × 10⁻² cm/s) to flanks (1.4 × 10⁻² cm/s) to swales (1.2 × 10⁻² cm/s), with claypans exhibiting values two orders of magnitude lower (4.6 × 10⁻⁴ cm/s). Mean grain-size composition shows a gradient from crests (90.6% sand, 9.0% silt, 0.3% clay) and flanks (86.9% sand, 12.6% silt, 0.1% clay), to swales (78.0% sand, 20.8% silt, 0.7% clay), and claypans (58.9% sand, 40.9% silt, 1.1% clay). Mineralogical analyses indicate quartz-rich sediments with hematite oxide coatings, with minor microcline, albite, and halite, as well as rare muscovite, and gypsum. The occurrence of evaporite minerals, interpreted with position-dependent hydraulic conductivity and grain-size trends, is consistent with moisture retention and evaporative concentration from ponding in claypans. These results show that dune position exerts a control on hydrology and geochemistry in arid linear dunes, providing a framework for interpreting transient water activity and preservation potential in planetary dune environments.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

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