11 Future Voices in Geoscience- Undergraduate Research Posters

This session is for two-year college and four-year college and university students presenting research posters in any subdiscipline of geosciences. Posters and presentations will be judged for awards.

Monday, 18 May 2026
8:00 AM - 5:30 PM
Alvarado D/E

Characterizing Enigmatic Banded Fault Fabrics in the Navajo Sandstone in Salt Valley, Utah

Paper number: 11-13
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Salt Valley, located northwest of Moab, Utah, is a graben formed through extensional collapse above a salt-cored anticline that produced normal fault sets that cut the overlying Jurassic Navajo and Entrada Sandstones. Brittle deformation in the Navajo sandstone is well-characterized, with normal faults and deformation bands commonly accommodating strain. Locally, the Navajo Sandstone on the southwest side of Salt Valley within Arches National Park exhibits eye-catching and enigmatic banding of light and dark material that differs in overall appearance and internal structure from other regionally documented structures. This study characterized the morphology of these banded fault fabrics (BFFs), deformation timing, and relationships with regional fault-zone kinematics to provide constraints on models for BFF formation.  

 

We documented twelve faults along the Tower Arch Trail within Arches National Park; ten of which contain the distinct BFF morphology. These faults dip primarily northeast ~60ยบ, with 3 dipping southwest, consistent with faults observed elsewhere in Salt Valley. All faults have normal-sense separation of 2-5m. BFFs are 0.1-3.0 m wide shear zones that consist of alternating bands of lighter and darker sandstone with varying proportions of iron-oxide enrichment and varying degree of color banding. Band development is strongest where iron-oxide nodules are abundant in the adjacent host rock. At the microscale, grain size within the BFFs is comparable to that of the undeformed Navajo Sandstone, though porosity is locally reduced via grain compaction and minor cataclasis. Grains in some BFFs have a weak preferential orientation, commonly associated with hematite infill. Tight folding of light and dark layers within BFFs is characterized by skinny limbs and thickened hinges. Cataclastic bands with typical grain-crushing and porosity reduction at the microscale crosscut undeformed Navajo Sandstone, and BFFs sharply truncate the cataclastic bands. Lozenges of Navajo Sandstone containing cataclastic bands and well-developed bedding are cross-cut and bounded by BFFs. 

 

These anomalous fault structures indicate a unique style of deformation that occurred in the Navajo Sandstone, which has not been previously documented. We determined the BFFs postdate both original bedding and cataclastic bands, with fault offsets and dips consistent with formation during larger-scale graben development. Determining the mechanisms by which these BFFs form, however, requires continued research. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410605

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