40 Aeolian Systems in Time and Space

This session explores research focused on all aspects of aeolian processes and landforms, including dunes, dust, and loess in modern and ancient aeolian systems on Earth and other planets.

Sunday, 19 October 2025
1:30 PM - 5:30 PM
HBGCC, 212AB

Paleosols, bioturbation, and interdune and non-eolian deposits of the Lower Jurassic Navajo Sandstone, Utah: Understanding erg records of environmental, ecologic, and climate change

Paper number: 40-10
Program: Technical Sessions
Time: 3:45 PM – 4:00 PM

Authors

Abstract

Eolian deposits of the Navajo Sandstone (Ss) of the Colorado Plateau are well described in the literature. However, interdune and non-eolian deposits––playa, fluvial, spring, and lacustrine––interstratified with the eolian deposits have been less studied and typically excluded from bounding surface classifications. This bias hinders fully understanding the changes in autogenic and allogenic processes that shaped the Navajo erg system. Recent research on the fill and bounding surfaces of interdune and non-eolian deposits indicates that they record changes in effective precipitation based on their lithofacies, trace-fossil associations, bioturbation patterns, and degree of pedogenesis. These deposits preserve wetting and drying cycles with varying amounts of sedimentation, bioturbation, and pedogenesis at different scales that produced patterns of eolian to fluvial and/or lacustrine deposits and back to eolian deposits. Accordingly, the types of non-eolian depositional environments and their lateral extent in the interdune spacing reflect the hydroclimate setting, groundwater profile (GWP), and accommodation. In general, increasingly greater amounts of effective precipitation coupled with diminished wind power produced increasing amounts of vegetative cover, above- and below-ground biodiversity, and soil formation, which retarded dune migration, resulting in greater landscape stability. This stability was achieved by vegetation growth on the dune stoss and crest, based on modern erg studies. The resulting fill patterns produced simple, compound, composite, and/or cumulative paleosol profiles, depending on the interplay between sedimentation, pedogenesis, and GWP. During periods of greater effective precipitation, the interdune hosted intermittent to perennial water bodies. Lacustrine carbonates, in particular, represent a regional, elevated groundwater table that sustained carbonate precipitation. Conversely, increasing aridity and wind power resulted in decreasing amounts of vegetative cover, above- and below-ground biodiversity, and pedogenesis, which allowed renewed dune migration and destabilized the landscape. These periods of diminished effective precipitation recorded ephemeral wetting events with little or no interdune deposition taking place. Thus, interdune deposits of the Navajo Ss are the principal record of changes in autogenic and allogenic processes in the erg system. Their sedimentary layering and bounding surfaces recorded the interplay between sedimentation, pedogenesis, and hydroclimate that produced wetting upward and/or drying upward intervals in each stratigraphic interval. Further study of the stratigraphic succession and lateral variability of interdune deposits in the Navajo Ss may provide key evidence of the climate setting through time.   

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

doi: 10.1130/abs/2025AM-412311

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