345 Silurian Radiolarian Zonation for the Caballos Novaculite, West Texas

Silurian radiolarian zonation for the Caballos novaculite, Marathon Basin, west Texas - BAP #345 This paper presents a local biozonation for Silurian radiolarians recovered from the Caballos Novaculite, Marathon uplift, Texas. Six measured sections representing 25-30 m of strata from the western half of the uplift have yielded abundant and moderately well-preserved radiolarian assemblages that can be subdivided into six biozones. The Rotasphaerid Superzone (Ro), contains the four oldest zones 1, 2, 3, and 4, and is defined by the first and last appearances of the superfamily Rotasphaeracea. The base of this superzone has not yet been determined in the Marathon uplift. All taxa chosen for this biozonation are commonly occurring, distinctive, robust forms that can be correlated from section to section, thereby meeting the criteria for establishing a practical and widely applicable biostratigraphic scheme. Three conodont assemblages co-occur with the radiolarians and show the youngest z