253-11 Preliminary Conodont and Fusulinid Biostratigraphy of the Wolfcamp B-Wolfcamp A Transition (Mid-Artinskian, Lower Permian) from Simpson Canyon Well 4045, Crockett County, Texas

Session: Conodonts from North America and Beyond - Honoring the Career of Dr. James E. Barrick

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Abstract:

Conodont and fusulinid samples from the Simpson Canyon 4045 well (Crockett County, TX) provide age control for a previously unconstrained core from the upper part of the “Wolfcamp Shale” in the southern Midland Basin of West Texas. Biostratigraphic integration of conodont and fusulinid assemblages is critical in Cisuralian (Lower Permian) marine successions, as conodont elements are the primary indices for international chronostratigraphic stage boundaries and fusulinid occurrences delineate North American regional stages (e.g., Wolfcampian, Leonardian) and substages. The cored interval (5996.6’-5876’) comprises mixed carbonate-siliciclastic slope deposits associated with gravity flows and hemipelagic sedimentation along the southeastern margin of the Central Basin Platform. Four 10” intervals of the Simpson Canyon 4045 core were sampled from depths of 5922’, 5911’, 5894’, and 5877’, with only the black shale-dominated horizon at 5877’ devoid of fusulinids. Insoluble residues from the four sampled core segments yielded conodont elements of Sweetognathus ex gr. clarki, Mesogondolella bisselli, and an aberrant, irregularly nodose sweetognathid morphotype that is possibly transitional from Sweetognathus clarki to Neostreptognathodus pequopensis. These conodont occurrences, particularly the sweetognathid taxa, indicate the 5911’ to 5877’ interval is mid- to upper Artinskian (mid-Lower Permian), which is correlative with the lower part of the Leonardian Stage in the North American regional schema. Fusulinid specimens recovered from three of the four intervals include Schwagerina hawkinsi (5922’), Schwagerina hessensis (5922’), Skinnerella schucherti (5922’), Skinnerella biconica (5911’), and Parafusulina allisonensis (5894’). Each of these fusulinid taxa were originally described from lower Leonardian carbonate shelf successions flanking the Midland and Delaware basins, with Schwagerina hawkinsi, Schwagerina hessensis, and Parafusulina allisonensis described from the Glass Mountains (Southern Shelf), Skinnerella schucherti described from the Sierra Diablo (Diablo Platform), and Skinnerella biconica described from the Baylor Mountains (Diablo Platform). Additionally, Schwagerina hawkinsi, Schwagerina hessensis, Skinnerella schucherti, and Skinnerella biconica have been previously reported from slope-related “Wolfcamp Shale” cores recovered from Howard and Glasscock counties in the central Midland Basin.

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

doi: 10.1130/abs/2025AM-6379

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