4 Sedimentary Systems and Provenance in the Western Cordillera

This session invites contributions on sedimentary processes, depositional environments, stratigraphic frameworks, and provenance evolution across western North America. Topics may include basin analysis, source-to-sink studies, and applications of stratigraphy to energy and environmental questions.

Wednesday, 22 April 2026
8:00 AM - 12:00 PM
LMH, Fiesta Terrace Salon

Yo-yo tectonics recorded in the Maniobra Basin of the southwestern US Cordillera

Paper number: 4-8
Program: Technical Sessions
Time: 10:20 AM – 10:40 AM

Authors

Abstract

The Cenozoic geologic history of the southwestern Cordilleran margin was shaped by the transition from a convergent to a transcurrent margin over the last 60 million years. Basinal strata preserved near the margin and from this pivotal transition period, however, are rare and mainly confined to forearc sediments on the Pacific plate that have been translated northwest along the San Andreas Fault (SAF) system. The Eocene Maniobra Formation, located east of the SAF and along the southern margin of the Mojave block, represents a unique exception that records the depositional and tectonic history of the southwestern Cordillera prior to and during the convergent – transcurrent tectonic mode switch. New mapping, lithofacies description, detrital zircon geochronology, and apatite thermochronometry in the Maniobra Basin reveal a yo-yo style tectonic history, with the following interpreted events: 1) rapid subsidence and deposition of the Maniobra Formation at 53 Ma, 2) uplift and exhumation from ca. 40 – 26 Ma, 3) renewed subsidence and deposition of the overlying Diligencia Formation from ca. 26 – 18 Ma, and 4) basin inversion, rotation, and transpression of the Maniobra – Diligencia from ca. 10 – 0 Ma. Initial subsidence at ~53 Ma created a >15 km-long, N-S oriented submarine canyon, suggesting rapid development of a large fluvial system that tapped into the Mojave Province. Subsequent uplift at ca. 40 Ma caused sub-aerial erosion and shifted the marine shoreline westward and/or southward. Early vertical oscillations recorded in the Maniobra Formation and preserved as depositional and structural features in the strata, require dynamic tectonic forcing likely driven by changes in subduction geometry and / or subduction and passage of large igneous provinces developed in slab lithosphere. Later oscillations are driven by regional extension, followed by transpressional strain imparted by the developing SAF.

 

 

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

doi: 10.1130/abs/2026CD-411065

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