Sequence stratigraphy of the Middle Eocene Claiborne Stage, US Gulf Coastal Plain

I present a stratigraphic analysis of the middle Eocene Claiborne Stage in Alabama and Mississippi based on surface exposures and conducted from the perspective of sequence stratigraphy. Sequences were identified based on observed lithologic transitions, with key surfaces and positions within a sequence often marked also by distinctive trace fossil horizons. Three third order sequences corresponding to the Tallahatta, lower/middle Lisbon, and upper Lisbon (Cook Mountain) Formations were recognized in outcrop-based studies. A previously unrecognized fourth sequence of similar magnitude was identified in the upper part of the upper Lisbon and may correlate with one reported from the subsurface. Smaller scale parasequence development within these sequences is also noted, and may in some cases be useful for correlation. This analysis will allow a better understanding of smaller-scale regional correlations and relative sea-level change through time in the Eastern Gulf Coastal Plain. Some uncertainty remains as to whether the Claiborne cycles are eustatic in origin, but the general agreement of my interpretations with the Haw and others (1987) curve and with workers in Texas and the Atlantic Coastal Plain suggests, with some exceptions, primary control by global sea level fluctuation.