Carbonate Sequences from the Valles-San Luis and Tuxpan Platforms (El Abra Formation; Cretaceous) and Their Paleoenvironmental Significance in a Sector of the Sierra Madre Oriental in the Subsoil of the Coastal Plain of the Gulf of México

Paleogeographic elements formed by the Albian and the Cenomanian carbonate sequences, from the Valles-San Luis Potosí platforms (PVSLP) and the Tuxpan platform, developed reef environments on their borders corresponding to the El Abra Formation. This formation comprises lagoon facies (El Abra member) and reefal facies (Taninul member). El Abra Formation is rich in fossil content, mainly represented by mollusks and foraminifera with scarce corals and algae. The rudist bivalves’ bioherms were typically from the Cretaceous reefs, while the gastropods and foraminifera miliolids inhabited the lagoonal area. Calcareous platforms are characteristic for tropical to subtropical areas in the Tethys realm shallow-water environments.