Anomalous Morrowan-Chesterian Correlations in Western Anadarko Basin: ABSTRACT

Abstract

Fossils recovered from cores of a thin lignitic shale and a coal in two widely separated wells in the western Anadarko basin show that the shale and coal beds are time-equivalent. Spore-pollen assemblages from the two intervals are identical and indicate a late Morrowan age. Coal from one well in the western Oklahoma Panhandle is from an interval generally considered as late Morrowan; the lignitic shale from a well near Liberal, Kansas, however, is from rocks widely accepted as early Chesterian--almost Meramecian. Considering that there is a span of several million years between early Chesterian and late Morrowan, two possible interpretations are presented. Either (1) identical spore-pollen assemblages are not sufficient evidence to distinguish between early Chesterian and late Morrowan or (2) some rocks currently accepted as of Chesterian age in the western Anadarko basin actually are limestone-shale facies of the Morrow Formation, and the relation between Morrowan sandstone-shale and Chester limestone-shale would not be one of onlap on an unconformable surface but, instead, a major facies change. In the two wells the interval between the Meramecian St. Genevieve Limestone and the Atokan 13-finger limestone is nearly equal and analysis of the geologic history of this interval lends support to the facies interpretation. Either interpretation is provocative and could have economic consequences. End_of_Article - Last_Page 551------------