3-D POTENTIAL FIELD INVERSION OF CAMP CLUBHOUSE CROSSROADS MAFIC INTRUSIVE PLUTON, COASTAL PLAIN, SOUTH CAROLINA

The Central Atlantic Magmatic Province (CAMP) at the Triassic-Jurassic boundary, is the largest known igneous province in the world. Under the Coastal Plain sediments of Georgia and South Carolina, the “J” seismic reflector was predicted to be produced by a CAMP lava flow. Recent studies of seismic and well data have shown that the “J” reflector is an unconformity and only locally a CAMP lava flow. To our knowledge, no previous attempt has been made to model the deeper geometry of the CAMP mafic intrusive bodies under the Coastal Plain. In the Clubhouse Crossroads area of South Carolina, seismic reflection, seismic refraction, and well data are available to constrain the shallow structure under the Coastal Plain sediments. We take advantage of a rich potential field dataset to predict the deeper structure of the CAMP mafic intrusive pluton at Clubhouse Crossroads. The CAMP plutons have both very high densities as well as high magnetic susceptibilities, which makes them ideal for simultaneous 3-D inversion techniques. We forward modeled the 3D shallow structure with seismic and well control, and then inverted for the shape of the deeper structures assuming realistic densities and magnetic properties. The resulting model for a CAMP pluton beneath the SE US Coastal Plain, will be useful to help estimate the volume of CAMP magmatic activity in the area of the South Georgia Rift, the geometric relation between intrusive bodies and rift structures, and the relationships between CAMP plutons, sills, dikes, and lava flows. In addition, CAMP diabases and basalts may form self-sealing storage reservoirs for CO² sequestration by injection wells.