24-6 The Provenance and Stratigraphic Record of Cordilleran Magmatic Arc Exhumation in the Lower Part of the Upper Cretaceous Crevasse Canyon Formation in West-Central New Mexico

Session: Advances and Applications in Geochronology for Interpreting Stratigraphic and Basin Records, Part I

Presenting Author:

Authors:

Abstract:

The Crevasse Canyon Formation in west-central New Mexico outcrops along the southeasternmost margin of the Colorado Plateau and records primarily fluvial sedimentation along the Seboyeta embayment during the Late Cretaceous (Coniacian-Santonian) development of the Cordilleran foreland basin. Although this stratigraphic interval has received a considerable amount of study throughout parts of northwestern New Mexico and the Southwestern U.S., very little is known about the depositional history provenance of these strata in west-central New Mexico. Throughout much of the New Mexico, the Crevasse Canyon Formation has been documented to represent nonmarine, fluvial sedimentation and marks the final stratigraphic transition from marine sedimentation to nonmarine sedimentation in the Cordilleran foreland basin.

New measured stratigraphic sections, paleocurrent data, sandstone modal composition trends, and U-Pb detrital zircon data from the lower parts of the Crevasse Canyon reveal a depositional system characterized by (1) isolated, cross-stratified channel sands encased in floodplain strata that contains fossilized leaves, stumps, woody debris, and charcolithified organic material, and (2) laterally extensive sandstone bodies that exhibit isolated, faint cross stratification. Paleocurrent indicators from sandstone units display a wide range of flow directions that include northeast, east, and dominantly southeast directed paleoflow. Sandstone modes from these strata have high relative abundances of quartz (primarily monocrystalline, followed by polycrystalline quartz and chert), outsized feldspar (plagioclase and K-Spar), and a range of lithic fragments that include isolated volcanic, metamorphic, and sedimentary lithic fragments. Plutonic lithic fragments are very common and occur in nearly all samples collected from measured sections.

U-Pb detrital zircon ages contains (1) Precambrian zircons that overlap with the Yavapai, Mazatzal, and Granite-Rhyolite, and Grenville provinces, (2) recycled Neoproterozoic and Early Paleozoic detritus from Mesozoic eolianites of the southwestern U.S., (3) Permian-Triassic zircons that overlap in age with granitoid sources of the Cordilleran magmatic arc. Elevated occurrences of Permian-Jurassic zircons coupled with widespread occurrences of plutonic lithic clasts and outsized feldspar grains indicate that this basin was receiving detritus largely from deeper, exhumed parts of the Cordilleran magmatic arc.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

© Copyright 2025 The Geological Society of America (GSA), all rights reserved.