Ichnology in Sequence Stratigraphic Studies: An Example from the Lower Paleocene of Alabama

Despite their sensitivity to paleoenvironmental changes that typically occur as a result of sea-level dynamics, ichnofossils have received little attention thus far in sequence stratigraphicstudies. Detailed ichno-sedimentological analyses of two Lower Paleocene depositional sequences contained within the Clayton and Porters Creek Formations of western Alabama demonstrate that degree of bioturbation, general ichnofabrics, and assemblages of discrete trace fossils vary significantly between the different component systems tracts within each sequence and between like systems tracts of the two sequences. These ichnological variations reflect changes in substrate consistency, physical environmental energy, sedimentation rate, and bottom- and/or pore-water chemistry that are consistent with both the phases and magnitudes of the associated sea-level cycles. These results illustrate the potential of extended ichnological studies in the testing and refinement of sequence stratigraphie models and resulting interpretations of sea-level histories.