ABSTRACT

The origin of the Florida Lineament, a major basement lineament which strikes northwest-southeast across the West Florida Shelf and southern Florida, is a key to the history of the Gulf of Mexico. Regional magnetic and gravity trends are truncated along the Florida Lineament. New geologic data from recent wells on the West Florida Shelf and magnetic anomaly data indicate that pre-Mesozoic basement terrains on opposite sides of the Florida Lineament were contiguous prior to Triassic-Jurassic volcanism and exhibit only minimal lateral offset across the Florida Lineament at present. The lack of major lateral offset of pre-Mesozoic basement terrains across the Florida Lineament and lithologic and geophysical data suggest that the lineament represents a Triassic-Jurassic extensional rift margin.

The Florida Lineament is interpreted to be the southeastward continuation of the well-documented peripheral fault system, which delineates the rifted continental margin of the northern Gulf basin. The continuation of the peripheral fault system along the Florida Lineament suggests that the tectonostratigraphic terrains associated with the Mesozoic producing trends of the northern Gulf basin may extend southeastward along the Florida Lineament.

The interpretation of the Florida Lineament as an extensional rift-margin places significant constraints on any tectonic model of the Gulf of Mexico region. A tectonic interpretation consistent with the constraints suggests that the West Florida Shelf and southern Florida region formed as the result of Triassic-Jurassic extension around a pole of rotation in central Florida. The central Florida pole of rotation is intermediate to the poles of rotation defined in 1982 by Shepherd and others, in 1985 by Pindell, and in 1987 by Salvador for the counterclockwise rotation of Yucatan out of the northern Gulf basin. This suggests that the region south of the Florida Lineament underwent extension synchronous with the rotation of the Yucatan block.