ABSTRACT

Deposits of the "traceable three" portion of the middle Atoka Formation are interpreted to represent deposition in a shelf setting. A depositional model for the sequence was developed through integration of both sedimentologic and biogenic data, and includes 8 individual facies. These facies are representative of (1) nearshore, (2) shoreface, and (3) shelf environments. Some of the distinctive criteria used in delineating the facies include, large scale slump and water escape features (nearshore), prolific trace fossils of the Cruziana Facies (shoreface), matrix supported shale clast conglomerates (shoreface, shelf), hummocky cross stratified sandstones (shelf), and trace fossils of the Zoophycus Facies (shelf). In addition to the presence of distinct sedimentologic and biogenic features, there is a tendency for shallow water structures and sand content to increase upward within measured sections, suggesting a regressive sequence.