31 Stratigraphic Studies in the Colorado Plateau

This session features stratigraphic studies that resolve the geological history of modern and ancient sediment routing systems, and their processes, within the Colorado Plateau using data from field, analytical, experimental and/or numerical modeling investigations.

Tuesday, 19 May 2026
1:30 PM - 4:00 PM
Alvarado C

Unresolved Geology Problems in Early Cretaceous Stratigraphy, Southeast Utah

Paper number: 31-5
Program: Technical Sessions
Time: 2:42 PM – 3:02 PM

Authors

Abstract

The Early Cretaceous Cedar Mountain and Burro Canyon Formations in southeast Utah were deposited in a vast foreland basin that stretched across the modern Colorado Plateau. This geologically active area, lying in the rain shadow of the Cordillera, contained large river systems that routed sediment from the Sevier Mountains and Mogollon Highlands during repeated climate fluctuations. These fluvial systems are preserved within a 500 km-wide depositional belt extending from central Utah to north-central New Mexico. The Colorado River serves as a symbolic divide between the correlative Cedar Mountain Formation (to the northwest) and the Burro Canyon Formation (to the southeast), including its supposed stratigraphic equivalent, the Jackpile Sandstone in northern New Mexico. This nomenclatural division, introduced in the mid-1900s, coincides with the foredeep-forebulge transition in the Sevier foreland basin, and this terminology persists in modern literature despite updates to regional stratigraphic packages and longstanding empirical evidence supporting its abandonment. Additional geochronological, geochemical, and petrological results across the depositional system are needed to shift consensus on the entire stratigraphic framework. Until resolved, these issues will hamper geological mapping efforts and limit our ability to derive accurate, temporally meaningful paleoenvironmental inferences.

The broad expanse of this outcrop belt, combined with complex local tectonics and shifting paleoclimates, requires holistic study of the entire depositional system. Lithostratigraphic correlation of sandstones is complicated by spatially restricted and often ephemeral fluvial systems, slow depositional rates, and downstream sediment recycling. Mudstones, where not eroded by fluvial incision, can offer a more continuous depositional record across such an expansive system. New chronostratigraphic studies have begun building a reliable framework for these strata, though data remain disproportionately concentrated in the Cedar Mountain Formation due to significant paleontological discoveries there. Clear delineation of stratigraphic boundaries is integral to understanding basin history. We focus on the unconformable basal contact with the Late Jurassic Morrison Formation—currently estimated at 15-million-years—and the disconformable, highly erosive upper contact with the overlying Naturita (Dakota) Formation, a transgressive sedimentary package recording prominent shifts in continental drainage patterns and paleoclimate. By integrating existing observations with novel chronostratigraphic work, we frame the current state of knowledge and propose solutions to outstanding geological problems to facilitate future 1:100,000-scale mapping in Utah.

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

doi: 10.1130/abs/2026RM-410483

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