The Subsurface Upper Frio Formation of Southeastern Louisiana and Correlations to the Paynes Hammock and Catahoula Formations in East-Central Mississippi

MARLIN, DONALD J., Marlin Geological Service, Baton Rouge, LA, and WILLIAM H. SCHRAMM, Louisiana Department of Environmental Quality, Baton Rouge, LA

The Frio Formation of the eastern Gulf coastal plain within southern Mississippi and southeastern Louisiana is characterized by calcareous and siliciclastic interbedding and small accumulations of hydrocarbons. Regional and local controls on reservoir quality sediments, the importance of carbonate deposits, and correlation to outcrop are addressed.

Regional Frio Formation structure and isopach maps suggest that outer shelf carbonate banks influence the orientation of siliciclastic trends and formed the east-west-trending Florida Parishes Frio embayment. The banks form during early transgressive system tract deposition and are commonly lepidocyclinid packestones. Late in Frio deposition, the embayment was infilled and is presently the location for new biogenic gas discoveries.

The upper Frio Formation appears to be correlative to a minimum of 3.5 ft (1.4 m) of the lower Paynes Hammock Formation outcrop in Wayne County, Mississippi, using a modified version of the graphic correlation method. The method identifies and integrates chronostratigraphic surfaces from electric logs. The surfaces are the upper parts of resistive carbonate lithofacies zones that are verified by conventional core analyses.

Measured section data spanning the lower Catahoula, Paynes Hammock, and Chickasawhay Formations from Wayne County, Mississippi, are presented that aid interpretation of Gulf Coast subsurface and outcrop relationships of the Chickasawhay Group. The data presented suggest that the lower Catahoula Formation contact is diachronous and that the upper Frio Formation occurs above the contact in the western Gulf Coast and below the contact in the eastern Gulf Coast.

AAPG Search and Discovery Article #91006 © 1991 GCAGS and GC-SEPM Meeting, Houston, Texas, October 16-18, 1991 (2009)