Structural Control on Upper Jurassic Sedimentation South of the Middle Ground Arch, Eastern Gulf of Mexico

Abstract

Reconstructing the paleogeograpy of the Eastern Gulf of Mexico during deposition of the Jurassic units remains a subject of interest because of the hydrocarbon potential of numerous drilling targets in the region. Using detrital zircon provenance analysis and paleo-wind transport directions, we have generated a provenance model for Upper Jurassic Norphlet Formation sandstone. This model implicates major structural control on sediment transport pathways; however, the role and spatial relationship of fault systems that bound the sediment transport pathways is less known. We analyzed three 2D seismic lines that cross the southern boundary of the Middle Ground Arch and Southern Platform in the Eastern Gulf of Mexico to determine the evolution of the bounding fault system. Each line depicts the structurally high Middle Group Arch/Southern Platform and Tampa Embayment basin fill to the southeast. Preliminary analysis suggests a minimum throw of approximately 500 meters (1,640 feet) on the bounding normal fault, which cuts through Paleozoic basement rocks. The downthrown side toward the Tampa Embayment has salt in the basin; however, the salt pinches out northward toward the bounding normal fault. The Norphlet and Smackover Formations also terminate northward toward this fault; however, the Haynesville Formation overlaps the fault. Erosional valleys cut into the basement rock of the Middle Ground Arch are up to 1 km (3,280 feet) deep and are filled with the Haynesville Formation. These data indicate the Middle Ground Arch/Southern Platform region was likely a low-lying structural feature until at least Middle Jurassic time. Uplift on the bounding normal fault occurred during Early-Late Jurassic time during deposition of the Norphlet and Haynesville formations. Erosional features on the Middle Ground Arch support that the Tampa Embayment was fed by material shed from this regional high and will have the Norphlet-Smackover equivalent units. By Middle-Late Jurassic time, deposition of the Haynesville Formation covered the bounding normal fault and the Middle Ground Arch, marking the end of extension.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016