SEQUENCE STRATIGRAPHIC RELATIONS OF THE FREDERICKSBURG AND WASHITA GROUPS, LOWER CRETACEOUS CARBONATE SHELF, TEXAS

Stratigraphic interpretations of the Fredericksburg and Washita groups on the Comanche carbonate shelf have been debated for many years. This research will address several ongoing questions regarding carbonate sequence stratigraphy of the Fredericksburg and Washita groups and test current stratigraphic models. The sequence boundary between the Fredericksburg and Washita groups, Albian Sequence Boundary Washita 1, is an iron-stained, bored hardground in north Texas and southeast Oklahoma. In the Western Interior the contact records the flooding of the North American Continent. However, southward the contact has been traced and interpreted differently by several published stratigraphic models. This study will characterize the origin of the Fredericksburg-Washita sequence boundary and test correlations of carbonate depositional cycles. To accomplish the objectives, petrographic, isotope, and measured section data was gathered from several outcrops and a core. Results reflect a sequence stratigraphic interpretation, tracing the Fredericksburg-Washita contact in north Texas (between the Kiamichi and Goodland formations) to south-central Texas (between the Person and Georgetown formations) as a continuous, unconformable surface. Applications of sequence stratigraphy provide an accurate method for predicting the thickness, quality, and distribution of reservoir rocks in the Fredericksburg Group.