NAGIHARA, SEIICHI, and JOHN G. SCLATER, Scripps Institution of Oceanography, University of California, San Diego and La Jolla, CA

ABSTRACT: Salt Geometry Constrained by Conductive Heat Flow Anomalies

Salt has a thermal conductivity three to four times greater than that of other sedimentary rock. The high conductivity causes a positive heat flow anomaly over a diapiric salt structure. The character of the conductive anomaly reflects the geometry of the salt body. Our intensive measurements over salt structures on the Texas continental slope, Gulf of Mexico have demonstrated that the heat flow indeed shows systematic and large scale variation that coincides with the thickness variation of the salt. This finding suggests that heat flow measurements may be a practical tool to constrain geometry of salt diapirs in deep water if effects of convective heat transfer caused by the movement of salt body and pore fluid migration are evaluated to be small. Matching the heat flow observations y applying a theoretical model provides the constraint on geometry. The simplest approach is to use a numerical, forward model. It must he three-dimensional, but to be practical, it should permit rapid computation. We have developed such a model for the heat flow anomalies observed over the salt structures on the Texas continental slope. The model uses the strongly implicit finite difference scheme and achieves a much faster convergence than other explicit or less implicit methods. We present examples of studies on (1) the sensitivity of the heat flow anomaly to the bottom geometry, and (2) thermal effects from neighboring salt structures.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.