T82 New Insights to the Dynamics of Stratigraphy and Sedimentation (Posters)

Sunday, 25 September 2016
9:00 AM - 5:30 PM
Exhibit Hall E/F

U-PB DETRITAL ZIRCON GEOCHRONOLOGY, MODAL COMPOSITION, AND PALEOFLOW TRENDS FROM UPPER CRETACEOUS NONMARINE STRATA IN SOUTHERN NEW MEXICO

Paper number: T82-14
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Abstract

New sandstone modal composition data, paleoflow trends, and U-Pb detrital zircon ages are summarized and interpreted from Upper Cretaceous nonmarine strata that outcrops throughout parts of southern New Mexico. Strata include Cenomanian–Campanian fluvial deposits of the Dakota Sandstone, Tres Hermanos Formation, and Crevasse Canyon Formation (Lower Member and Ash Canyon Member).

Overall, sandstone modal composition of Upper Cretaceous strata is dominated by relatively high occurrences of monocrystalline quartz, moderate occurrences of lithic fragments (volcanic and metamorphic) with minor amounts of feldspar (Q=63%, F=5%, L=32%). The Dakota Sandstone has the highest relative abundance of quartz (Q=73–97%) and transitions upsection to more lithic-rich sandstone in the overlying Crevasse Canyon Formation (L=36-55%). Paleocurrent measurements (n=389) exhibit east- to northeast-directed paleoflow trends. The Dakota Sandstone has average paleoflow directions of 108° and 50° whereas the Tres Hermanos Formation has average paleoflow directions of 165°, 93°, and 109°. Overlying strata of the Crevasse Canyon Formation have average paleoflow directions of 100°, 118°, and 108°. Detrital zircon geochronology (N=9) from Upper Cretaceous nonmarine sandstones of the Dakota Sandstone, Tres Hermanos Formation, and Crevasse Canyon Formation show peak ages of 2692, 1681, 1422, 1058, 613, 412, 223, 168, 94 Ma.

Based on trends summarized above, a sediment dispersal model is favored where the Dakota Sandstone, Tres Hermanos Formation, and Crevasse Canyon Formation were sourced from recycled orogen and arc source areas that were located in the west-southwest parts of the United States and Mexico Cordillera. Precambrian zircons overlap in age with the Yavapai-Mazatzal, Granite-Rhyolite, and Grenville provinces of the southwest United States. Permian-Triassic age detritus overlaps in age with granitoid rocks that outcrop in northwestern Mexico. Jurassic–Cretaceous age zircons overlap with Mesozoic magmatic provinces in the Mogollon Highlands as well as the southern Cordilleran magmatic arc provinces in the southwestern United States and northwest Mexico (e.g., Peninsular Ranges). The Guerrero superterrane and Caborca block in northwestern Mexico were also likely source areas.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-287549

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