Abstract: Episodic Uplift and Sedimentation in Post-Pennsylvanian Geologic History of Southeastern United States

Richard L. Bowen

Episodic uplift involving the southern Appalachians and Piedmont of the southeastern part of the United States has controlled strongly the character of Mesozoic and Cenozoic sedimentation in regions of the northeastern Gulf of Mexico, the Florida platform, and the southeastern Atlantic coastal plain and shelf. Typically, interior uplifts are reflected in sedimentary cycles of the peripheral regions, and within gross limits the dimensions, magnitudes, and shifting boundaries of the uplifts are resolvable from the volumes, sedimentary facies, and distribution of the clastic rocks accumulated during each cycle within the peripheral regions. Cumulative vertical post-Pennsylvanian movements are almost 20 km in the southeastern seaboard region.

Major pulses of vertical movement occurred in the later Jurassic, middle Cretaceous, early Paleogene, and late Neogene. Minor uplift pulses occurred in the Late Triassic, Early Cretaceous, and early Neogene. Significant volcanism is associated with the Late Triassic fault-block fracturing. Other pulses of volcanism occurred in the Late Cretaceous and Paleocene(?), and extensive Jurassic volcanism in southern Florida recently has been reported. Typically, each uplift pulse is followed by rapid erosion to near base level, a condition reflected in the associated sedimentary cycle by a shift toward fine-grained deposits with increased nonclastic content. Intervals between pulses of uplift appear to range between 25 and 50 m.y. in this region.

Within this geographic region, post-Pennsylvanian clastic sedimentation corresponds approximately in volume with the quantity of material eroded from the interior Appalachian-Piedmont subdivision, but there also has been a net addition of more than 1 million cu km of nonclastic sediment, the major part of which is the carbonate rocks of the Florida platform.

AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA