Results of a recently completed gravity investigation suggest that basement offsets produced by normal faulting are the sources of observed gravity and magnetic anomalies in northwest peninsular Florida (Lafayette, Dixie, Gilchrist, and Levy Counties). A series of parallel fault-block basins and uplifts is proposed as the dominant basement structure. These basins and uplifts and the Southwest Georgia Embayment developed in response to the same regional stress field in early Mesozoic time.
Two-hundred sixteen gravity stations have been established and correlated with the International Gravity Standardization Net. Bouguer anomaly values have been derived for each station and regional gravity components analyzed, using trend-surface analyses. Geologic cross sections have been made on the basis of available stratigraphic information. The gravity effect for each section was calculated, using the method of polygons. Basement structural interpretations were iteratively adjusted within geologic constraints until close agreement was achieved between calculated and observed gravity profiles.