Several lines of evidence suggest that the Gulf of Mexico opened synchronously and in the same northwest-southeast direction as the central North Atlantic, from about 180 to 130 Ma. The Atlantic and Gulf spreading centers were linked by left-lateral transform faults across the Florida-Bahamas platform. To the west, spreading was accommodated by left-lateral transform faults (megashears) across Mexico.

The basin and uplift structure of the northern Gulf Coast can be interpreted in terms of northwest-southeast rifting before the Gulf and Atlantic opening began. Alternatively, early rifting could have been a result of north-south motion between North America and Africa-South America. The latter inference is suggested by correlations between pre-Mesozoic Florida and Africa basement terranes as well as the crustal fabric of the northern Gulf Coast.

Basin formation in the northern Gulf Coast probably involved shallow, closely spaced graben-horst formation combined with larger scale ductile thinning of the lower crust during rifting. Following the end of rifting the sedimentary record indicates that the basin subsided in an exponential manner, as would be predicted from thermal models of sedimentary basin formation.

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