Latest Guadalupian (Middle Permian) Radiolarians from the Reef Trail Member of the Bell Canyon Formation, West Texas

Maldonado, Amy L.¹, Paula J. Noble¹, Gorden L. Bell², Yuxi Jin³ (1) University of Nevada, Reno, Reno, NV (2) Guadalupe National Park, Salt Flat, TX (3) University of Nevada, Reno, Reno,

Radiolarians recovered from the upper part of the Reef Trail Member of the Bell Canyon Formation, Delaware Basin, are the youngest radiolarian fauna recovered from the Guadalupe Mountains, west Texas. Radiolarians occur in a .5-1.0 meter interval consisting of finely laminated limestone approximately 3.5 meters below the contact with the overlying evaporitic Castile Formation. They are uppermost Guadalupian, occurring in the Clarkina postbitteri conodont zone and Paraboultonia splendens fusulinid zone. Five moderately to well preserved samples yielded abundant radiolarians, including abundant Albaillella sp. aff. yamakitai, abundant Follicucullus scholasticus, several species of Latentifistula, 2 species of Ruzhencevispongus, Pseudoalbaillella fusiformis, many forms of Entactinaria, and a proposed new genus of Corythoecidae. This is the youngest known appearance of the family Corythoecidae; the previous range was from upper Devonian through lower Permian. Many of the albaillellid and stauraxon species have been used for biostratigraphy in Guadalupian sections from Asia and their range, persistence, and utility as biomarkers in North America can now be evaluated. Radiolarians in this assemblage can be compared to the upper Guadalupian Follicucullus scholasticus-Follicucullus ventricosus and the lower Wuchiapingian Follicucullus charveti-Albaillella yamakitai zones established in Japan and the GSSP in China. Additionally, this assemblage can be compared to middle Permian sections in north-central Nevada and Russia where similar faunal assemblages have been described. Lithologically, the west Texas section is one of the best preserved uppermost Guadalupian basinal facies intervals and this assemblage will be useful in correlating middle Permian radiolarian biozones between North America and Asia.