Abstract: The Carrizo Formation of Smith County and the East Texas Basin: A Proposed Sand-Rich Marine-Dominated Model

Jeffrey D. Lauman, M. Carey Crocker, R. Larell Nielson

The Carrizo Formation of the Lower Eocene Claiborne Group of Smith County, Texas, and the East Texas Basin is proposed to have been deposited in marine-dominated strandplain and shallow marine environments. Analysis of 538 petroleum industry logs, 123 water well logs and records, and four sidewall cores suggest that the dominate Carrizo depositional environments were near-shore and shallow marine. There currently does not exist a detailed geological study including: cross sections, structure map, and isopach map of the Carrizo Formation covering the East Texas Basin. Over the last 30 years, conventional descriptions such as a "homogeneous multi-lateral fluvial sand" have been used to compare the Carrizo Formation with the Wilcox Group.

Extra-basinal tectonic compressive forces from the southwest and west combined with eustatic sea level rises produced a marine stratigraphic clastic package. The Early and Middle Carrizo transgressive depositional environments in the East Texas Basin may have consisted of: onshore erosional environments containing small streams, strandplain-freshwater lakes, shoreface, barrier bars, and shallow marine environments along the basin's axis. The Late Carrizo transgressive depositional environments may have resembled the Nacatoch Formation (Upper Cretaceous) depositional environments. Along the basin's axis and extending northeast into northwest Louisiana there may have been shallow marine sand dominated environments influenced by northeast-southwest long-shore currents.

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana