LATE JURASSIC SEDIMENT TRANSPORT PATHWAYS INTO THE EASTERN GULF OF MEXICO AND IMPLICATIONS FOR TERRANE CONFIGURATIONS

Provenance analysis of Upper Jurassic Norphlet sandstone from the eastern Gulf of Mexico (EGOM) indicates sediment distribution in the EGOM was largely controlled by structural configuration of the underlying rifted basement, which in turn was inherited from patterns of terrane accretion along the ancient Laurentian-Gondwanan margin. Zircon grains from core samples in southwestern and south-central Alabama are characterized by prominent zircon age populations of 360-760 Ma, 950-1900 Ma, and 2500-3000 Ma, consistent with derivation from Laurentian-affinity Appalachian sources. Dipmeter data indicate a southerly transport direction. Zircon grains from two cuttings samples from the Destin Dome region major zircon populations of 540-580 Ma and 2000-2200 Ma zircons consistent with derivation from the Gondwanan Suwanee terrane. Dipmeter data indicate a westerly or northwesterly transport direction. Between these two regions in Alabama, zircon grains from core samples yield subequal proportions of both Gondwanan- and Laurentian-affinity zircons. Dipmeter data indicate and mixed westerly/northwesterly/southerly transport direction. Thus, zircon age populations and dipmeter data from the Destin Dome region indicate that a transport system may have flowed through the northeast-southwest trending graben system that developed to the south of the Suwanee suture during the Late Triassic to Early Jurassic rifting of Pangea. In addition, another transport system was in place that drained southward from the Appalachian orogen throughout western Alabama. Where the data indicate mixed zircon populations and dip directions, northwest eolian transport likely caused Gondwanan-affinity zircons to mix with northerly derived Laurentian-affinity zircon. The graben transport system identified in the Suwanee terrane persisted through Upper Jurassic time because U-Pb detrital zircons in the younger Haynesville Formation are similar to those in the Norphlet Formation indicating consistent transport pathways.