Major orogenesis affected the southern rim of the Gulf basin during late Paleozoic, middle Cretaceous, and Laramide times. Post-Laramide deformation has been dominantly epeirogenic or fault movements of normal or strike-slip character. Many tectonic features of southern Mexico and northern Central America are continuous beneath the adjacent Gulf of Mexico and/or Caribbean Sea. The following examples are cited: (1) Zacatecas zone-boundary of zones 3 and 4 of Bryant et al., (2) Trans-Mexican volcanic belt-Teziutlan massif-southern limit of zone 4 of Bryant et al.-Pera Salient-Progreso shear zone of northern Yucatan-Yucatan Channel uplift, (3) Ticul fault and Nuevo-Arenas swell, (4) Maya Mountains-Glovers Reef High-Cayman/Misteriosa Ridge-Sierra Maestra of Cuba, (5) San Cris obal-Comitan fault zones-Chixoy-Polochic and Motagua Fault zones-Bonacca Ridge, (6) Ulua graben of Honduras-downfaulting of continental margins of British Honduras and Quintana Roo.

Evaporite deposits are widespread in the southern Gulf. Diapirs are common in the Isthmian region of Mexico and extend northward to the Sigsbee Deep west of the Campeche Banks. Probable salt ridges are found in Bryant et al. zones 1-4. Significant quantities of Cretaceous evaporites underlie the Yucatan platform and may extend northward beneath the Campeche Banks. Salt diapirs are known to be present in Cuba. It is postulated that the salt in the Isthmian basin of Mexico may also be of Cretaceous age and continuous with the Yucatan deposits. The age and distribution of the salt are critical in understanding the Mesozoic history of the southern Gulf. It is doubtful that appreciable quantities of evaporites underlie easternmost Yucatan or are present in the Yucatan basin (northern Carib ean), but more detailed knowledge of this area is necessary. Cretaceous evaporites are present in Guatemala and it is possible that they may extend beneath the northern Caribbean.

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