# AAPG Bulletin

Abstract

AAPG Bulletin, V. 89, No. 3 (March 2005), P. 311-328.

DOI:10.1306/10280404026

## Gulf of Mexico tectonic history: Hotspot tracks, crustal boundaries, and early salt distribution

### Dale E. Bird,1 Kevin Burke,2 Stuart A. Hall,3 John F. Casey4

1Department of Geosciences, University of Houston, Houston, Texas; present address: Bird Geophysical, 16903 Clan Macintosh, Houston, Texas 77084; dale@birdgeo.com
2Department of Geosciences, University of Houston, Houston, Texas; kburke@uh.edu
3Department of Geosciences, University of Houston, Houston, Texas; sahgeo@uh.edu
4Department of Geosciences, University of Houston, Houston, Texas; jfcasey@uh.edu

## ABSTRACT

A Late Jurassic mantle plume may have generated hotspot tracks on the North American plate and the Yucatan Penninsula tectonic block as the Gulf of Mexico opened (ca. 150 Ma). The tracks are identified from deep basement structural highs that have been mapped by integrating seismic refraction and gravity data. They are associated with high-amplitude, distinctive gravity anomalies that provide the basis for a kinematic reconstruction that restores the western ends of the hotspot tracks with a 20 clockwise rotation of the Yucatan block or almost one-half the total rotation required to open the Gulf of Mexico Basin. The duration of track generation is estimated to have been about 8–10 m.y. or almost one-half the total time required to open the Gulf of Mexico Basin. Prior to this rotation, extension of continental crust over a 10–12-m.y. interval was the result of approximately 22 of counterclockwise rotation and crustal thinning. Autochthonous salt appears to be confined to the continental flanks of the hotspot tracks, confirming that salt was deposited during continental extension and not after ocean floor had begun to form. A prominent gravity anomaly along the western boundary of the basin is interpreted to be produced by a marginal ridge, which was created along the ocean-continent transform boundary as the basin opened. The eastern flank of this marginal ridge and the northernmost, easternmost, and southernmost terminations of the hotspot tracks are interpreted to coincide with the oceanic-continental crustal boundary in the basin.

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