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NAGIHARA, SEIICHI, Scripps Institution of Oceanography, University of California-San Diego, La Jolla, CA; LILA M. BECKLEY, ARCO Oil and Gas Company, Bakersfield, CA; E. WILLIAM BEHRENS, University of Texas at Austin, Austin, TX; and JOHN G. SCLATER, Scripps Institution of Oceanography, University of California-San Diego, La Jolla, CA

ABSTRACT: Characteristics of Heat Flow Through Diapiric Salt Structures on the Texas Continental Slope

We characterized heat flux through two diapiric salt features in deep (> 1080 m) water on the Texas continental slope. Sediment stratigraphy and salt top morphology, delineated by a previous single channel seismic reflection survey, provided inferences on the two salt structures; one is a cylindrical stock of about 5 km in diameter and the other is a subcircular salt tongue of about 10 km in diameter. Heat flow measurements (74) showed large-scale, positive anomalies (factor of two to three relative to the background flux of approximately 32 mW/sq m) over the two features. Variation of the heat flow coincides with the thickness valiation of the salt inferred from the seismic records. We believe that these anomalies mainly reflect the high thermal conductivity of the salt and give m jor constraints on geometry of the salt bodies. Our three-dimensional, steady-state thermal model provides estimates on the feeder depths of the two salt features. We also analyzed secondary thermal effects, such as (1) differential sedimentation, (2) salt movement, and (3) unknown fluid migration. Effects 1 and 2, based on the seismic stratigraphy, suggest that these effects alone can produce a significant positive anomaly (approximately 20%) and should be reflected in thermal modeling. The episodic nature of effect 3 does not seem to produce persistent, large-scale thermal anomalies.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.