302-2 Deposition of Cyclic Facies in the Navajo Sandstone Influenced by Seasonal Wind Changes

Session: Aeolian Systems in Time and Space (Posters)

Poster Booth No.: 155

Presenting Author:

Abigail Tucker

Authors:

Tucker, Abigail¹, Sylvester, Zoltan², Lawton, Timothy³

(1) Jackson School of Geoscience, University of Texas at Austin, Austin, Texas, USA, (2) Jackson School of Geoscience, University of Texas at Austin, Austin, Texas, USA, (3) Jackson School of Geoscience, University of Texas at Austin, Austin, Texas, USA,

Abstract:

The use of satellite imagery has revolutionized aeolian sedimentology, leading to a significant increase of research on modern dune morphology. However, much less is known about the links between dune morphology and the stratigraphy that dunes create. Notably, repetitive facies cycles have been recorded in the Lower Jurassic Navajo Sandstone, other aeolian sandstones, and modern dune fields such as White Sands National Park since the 1980s. These cycles are inferred to represent seasonal variations in wind direction, but the cyclic characteristics have not been documented in much detail. They are well exposed at several locations in southern Utah (Buckskin Gulch, Kanab Canyon, and Zebra Canyon), and consist of grain flow foresets with time-equivalent wind ripple strata overlain by a wedge of wind ripples and grain fall laminae. We collected photogrammetry data using a drone and a digital camera at several sites and constructed three-dimensional models using Structure-from-Motion software. Dip of the repetitive facies were measured at multiple outcrops. The grain flow foresets maintained a regular dip interval of 23-26° while the wedge facies maintained a regular dip interval of 9-12°. The photogrammetry data combined with dip data has allowed us to create orthomosaics, from which true thickness of the grain flow facies and other units can be measured. We anticipate that our data will provide further evidence that seasonal wind changes are reflected in aeolian stratigraphy.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-4827

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