22 Evolution of Cordilleran-type orogenic systems (Posters)

This session seeks contributions that connect surface, crustal, and mantle processes associated with Cordilleran systems, specifically addressing geodynamics, kinematics, magmatism, uplift, erosion, basin subsidence, and sediment dispersal in ancient and modern settings.

Thursday, 23 April 2026
8:00 AM - 5:30 PM
LMH, 5th Floor Chapel

Wedge-top Deposition in the McCoy Foreland Basin: New Evidence From the Livingston Hills

Paper number: 22-6
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The McCoy basin is exposed across a ~200 km wide east-west swath of southeastern California–western Arizona and preserves the anomalously thick (>7 km) McCoy Mountains Formation. Recent work suggests that deposition within the McCoy basin occurred entirely during the Cretaceous (ca. 137–70 Ma) in the foredeep of a relatively deep-water flexurally loaded basin based on stratigraphic sections exposed in the McCoy Mountains, California. Regional evidence supporting this foreland basin interpretation has been limited, particularly in areas outside the McCoy Mountains. The Livingston Hills strata in western Arizona preserve a ~3.5 km thick record of clastic sedimentary rocks that have been lithostratigraphically correlated with the McCoy Mountains Formation in California, however, the age for this succession and its tectonic significance remain unconstrained. This study presents detailed stratigraphic sections and the first detrital zircon ages from the Livingston Hills that suggest these strata were deposited during the Late Cretaceous after ca. 96 Ma by south-flowing deep-water turbidite systems and are correlative with the upper portion of the McCoy Mountains Formation in California. Provenance data indicate that sediments were primarily derived from metamorphosed Early Jurassic sedimentary units and Proterozoic basement in the Southern Plomosa Mountains. These results, combined with growth strata documented in the Livingston Hills, provide evidence for wedge-top synorogenic deposition in the McCoy retroarc foreland basin, consistent with flexure in front of a south-verging orogenic wedge such as the Maria fold-thrust belt.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-410997

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