New Sedimentology and Provenance From Upper Cretaceous Strata in Southern New Mexico: Implications for Sediment Dispersal Along the Southern Margin of the Sevier Foreland Basin

Abstract

Nearly continuous sections of Upper Cretaceous Sevier foreland basin strata are exposed in outcrop throughout parts of southern New Mexico. Here, Cenomanian–lower Campanian stratigraphy are defined from base-to-top by (1) fluvial and shoreline deposits of the Dakota Sandstone, (2) lower- and upper-offshore deposits of the Mancos Shale (Tokay Tongue) and Bridge Creek Limestone and Sandstone Members, (3) shoreline deposits of the Atarque Sandstone Member and fluvial strata of the Tres Hermanos Formation, (4) lower- and upper-offshore strata of the D-Cross Tongue of the Mancos Shale and lower shoreface and shoreline strata of the Gallup Sandstone, and (5) fluvial strata of the Crevasse Canyon Formation. Presented here are new sedimentologic data from the Coniacian–lower Campanian Crevasse Canyon Formation and new provenance data (sandstone modal composition and U-Pb detrital zircon geochronology) from nonmarine parts of the Dakota Sandstone, Tres Hermanos Formation, and Crevasse Canyon Formation. New sedimentary facies and architectural element analysis from the Crevasse Canyon Formation reveal an upsection transition from more meandering to braided stratigraphic architectures. The lower member of the Crevasse Canyon Formation is thought to be Coniacian–Santonian in age and is characterized by lenticular (channel) sandstone units that exhibit well-developed lateral accretion surfaces. Lenticular units are bound by tabular sandstone and pedogenically-altered mudstone deposits that are interpreted to represent floodplain crevasse splay sedimentation and paleosol development, respectively. The upper part of the Crevasse Canyon Formation (Ash Canyon Member) is thought to be lower Campanian in age and consists primarily of amalgamated lenticular sandstone units that are interpreted to represent a braided channel complex. Trends in detrital modes from the Dakota Sandstone, Tres Hermanos, and Crevasse Canyon Formations show an upsection transition from more quartz-dominated to more lithic-dominated compositions. The basal Dakota Sandstone has a higher relative abundance of quartz compared to the Tres Hermanos and Crevasse Canyon Formations, each of which have higher relative abundances of lithic volcanic fragments and feldspar. New sedimentologic and provenance data from Upper Cretaceous strata in southern New Mexico provide a means for testing trends in exhumation and sediment dispersal along the southern margin of the Sevier foreland basin.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015