142-5 XRD and Major Element Analysis of the Wedington Sandstone Member, Arkansas, as a Terrestrial Analog to the Shenandoah Formation, Western Fan, Jezero Crater, Mars

Session: Geomorphology and Landscape Evolution of Mars (Posters)

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Abstract:

Terrestrial analogs guide how we read Martian sedimentary structures, but morphological similarity does not guarantee compositional or process similarity. Previous work on the Mississippian Wedington Sandstone Member (WSM) in northwest Arkansas shows it is a topographically inverted river-delta deposit with coastal backwater signatures, setting it apart from megafan analogs commonly used for Martian fans. The Shenandoah Formation, the lower 25 m of Jezero crater's western-fan eastern scarp, is a sand-dominated succession found on Mars that records a shift from distal alluvial-fan deposits through a saline lake to river-delta progradation. We test whether bulk chemistry supports using the WSM as more than a morphological proxy for that succession.

Using Perseverance traverse and sol data in GIS, compared against published Shenandoah member boundaries and Planetary Data System images, the Rockytop member stood out as the strongest visual analog to the WSM, based on shared soft-sediment deformation and honeycomb weathering.

XRD and major element analysis were conducted on samples from an exposed WSM outcrop near Bayyari Park. We sampled at 6-inch vertical intervals, pulverized powders in a ball mill, and screened them by X-ray diffraction (XRD). Samples spanning a range of mineral signatures were analyzed for major elements by X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) and compared with published Perseverance geochemistry from Rockytop/Shenandoah intervals.

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