Jurassic evolution of the Gulf of Mexico salt basin Michael R. Hudec, Ian O. Norton, Martin P. A. Jackson, and Frank J. Peel ABSTRACT We present a new hypothesis for the Jurassic plate-tectonic evolution of the Gulf of Mexico basin and discuss how this evolution influenced Jurassic salt tectonics. Four interpreta- tions, some based on new data, constrain the hypothesis. First, the limit of normal oceanic crust coincides with a landward- dipping basement ramp near the seaward end of the salt basin, which has been mapped on seismic data. Second, the deep salt in the deep-water Gulf of Mexico can be separated into provinces on the basis of position with respect to this ramp. Third, paleodepths in the postsalt sequence indicate that salt filled the Gulf of Mexico salt basin to near sea level. Fourth, seismic data show that postsalt sediments in the central Louann and the Yucatan salt basins exhibit large magnitudes of Late Jurassic salt-detached extension not balanced by equivalent salt-detached shortening. In our hypothesis, Callovian salt was deposited in pre- existing crustal depressions on hyperextended continental and transitional crust. After salt deposition ended, rifting continued for another 7 to 12 m.y. before sea-floor spreading began. During this phase of postsalt crustal stretching, the salt and its overburden were extended by 100 to 250 km (62–155 mi), depending on location. Sea-floor spreading divided the northern Gulf of Mexico into two segments, separated by the northwest-trending Brazos transform. The eastern segment opened from east to west, leaving the Walker Ridge salient in the center of the basin as the final area to break apart. In some areas, salt flowed seaward onto new oceanic crust, first con- cordantly over the basement as a parautochthonous province, then climbing up over stratigraphically younger strata as an allochthonous province. AUTHORS Michael R. Hudec  Bureau of Economic Geology, University of Texas at Austin, Austin, Texas; michael.hudec@beg.utexas.edu Michael R. Hudec received his Ph.D. from the University of Wyoming in 1990. He joined the Bureau of Economic Geology in 2000, where he codirects the Applied Geodynamics Laboratory. His current research interests include the evo- lution of salt basins and salt-sheet emplacement mechanisms. He is a recipient or corecipient of the Matson, Braunstein, and Levorsen awards of AAPG. Ian O. Norton  Institute for Geophysics, University of Texas at Austin, Austin, Texas; norton@utig.ig.utexas.edu Ian O. Norton received his Ph.D. from the Uni- versity of Witwatersrand in 1978. He worked for ExxonMobil from 1981 to 2007, primarily in regional analysis and plate-tectonic modeling. After retirement, he joined the University of Texas Institute for Geophysics as a senior re- search fellow. His current research interests in- volve the structural evolution of passive conti- nental margins. Martin P. A. Jackson  Bureau of Economic Geology, University of Texas at Austin, Austin, Texas; martin.jackson@beg.utexas.edu Martin P. A. Jackson received his Ph.D. from the University of Cape Town in 1976. After teaching, he joined the Bureau of Economic Geology in 1980 and founded the Applied Geodynamics Laboratory in 1988. He has received several AAPG awards: the Sproule Award, the Matson Award, the Dott Award, and the Berg Out- standing Research Award for his research on salt tectonics. Frank J. Peel  BHP Billiton Petroleum (Americas) Inc., Houston, Texas; Frank.FJ.Peel@bhpbilliton.com Frank J. Peel received his Ph.D. from the Uni- versity of Oxford. He joined BP in 1985 and BHP in 1996, where he is a senior geoscience advi- sor, with interest in structural geology and salt tectonics. Current interests involve the structural evolution of passive continental margins, and multiphase fluid flow in hydrocarbon basins. He is a recipient of the Matson Award of AAPG. Copyright ©2013. The American Association of Petroleum Geologists. All rights reserved. Manuscript received May 3, 2012; provisional acceptance July 23, 2012; revised manuscript received January 28, 2013; final acceptance April 1, 2013. DOI:10.1306/04011312073 AAPG Bulletin, v. 97, no. 10 (October 2013), pp. 1683 – 1710 1683