MEYER, BEVERLY D., Dept. of Geosciences, Texas Tech University, Lubbock, TX
ABSTRACT: Conodont Biostratigraphy of Devonian Strata of West Texas and Eastern New Mexico
Dating of Devonian strata in the Permian Basin of West Texas and eastern New Mexico, and the Marathon Basin of West Texas is achieved using conodonts, and correlation to other North American shelf successions are effected. In the Permian Basin, the Silurian-Devonian boundary is located within the Frame Formation of the Wristen Group. Conodont faunas indicate an Early Devonian (Lochkovian) age for the upper Frame. Early Devonian (Pragian-Emsian?) conodonts occur in the carbonate packstone and grainstone of the Thirtyone Formation.
Two distinct conodont faunas are found in the Woodford Formation. The lower fauna occurs as stratigraphic leak into the underlying heavily karsted Silurian carbonate section, and in green and dark gray shales of the basal Woodford. This fauna ranges in age from the latest Givetian to early Frasnian (late Middle to early Late Devonian). The second Woodford conodont fauna, restricted to the black, organic-rich shales of the Woodford Formation, is Late Devonian (Famennian) in age. Early Mississippian (Kinderhookian) conodonts have not been recovered from the Woodford in the West Texas and eastern New Mexico subsurface, indicating that the Woodford is entirely Devonian age in the Permian Basin.
Conodont faunas of the Caballos Novaculite will be investigated and compared to the faunas of the Permian Basin.
Reworked Devonian conodonts from the Early Pennsylvanian Dimple Limestone in the Marathon Basin will also be compared to Permian Basin faunas to resolve the source area of transported carbonate sediments.
AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid