DETAILED ARCHITECTURE OF THE SUB-COASTAL PLAIN SOUTH GEORGIA BASIN AS REVEALED BY GEOPHYSICAL DATA

The South Georgia Basin (SGB) is located at the southern end of a string of Mesozoic rift basins stretching from eastern Canada to the southern United States. The SGB was originally proposed based upon the lithological equivalency of sedimentary and mafic igneous rocks encountered in deep wells through Coastal Plain sediments and those of the Newark Supergroup. Previous analysis of magnetic and COCORP seismic reflection data has shown a complex basin structure with smaller basins of variable thickness bounded by faults oriented parallel to preexisting structures in the Appalachian Piedmont and the proposed suture between the Suwannee Terrain of inferred African affinity in SE Georgia and Florida and Laurentian crust to the north. Gravity and magnetic data over a large area of southern and central Georgia were analyzed using several methods, including Potential Field Attributes and Rotational Invariants. There results were then used to generate models of the SGB constrained by well and seismic reflection data. The modeling reveals multiple block-faulted subbasins of 2-6 km depth oriented sub-parallel to older structures. This result is consistent with tectonic models of initial rifting along a preexisting zone of crustal weakness followed by a change in the locus of rifting to the east as stress fields reoriented over time.