ABSTRACT

In Alabama, Upper Cretaceous depositional sequence stratigraphy has been strongly affected by second-, third-, and fourth-order changes of sea level. In the upper Santonian to uppermost Maastrichtian section (85 to 67 Ma), second- and third-order sea-level changes owing to eustacy and third- and fourth-order sea-level changes owing to both local and regional tectonic events are recognized. Effects of second-order eustatic change are gross changes in depositional strike and systematic variations maximum clastic sedimentation rate. Effects of third-order eustatic change and local and regional tectonic events are related to directly to depositional sequence development. Fourth-order depositional sequences (episodic parasequences) are related to regional tectonic events. Tectonically affected depositional sequences are delineated by chronocorrelation with independently verified and dated local and regional (plate-wide) episodes of disturbance and comparison with the global synthesis of coeval coastal-onlap depositional sequences.