WILSON, JAMES LEE
Consultant, New Braunfels, TX

Abstract: The Cupido-Sligo reef trend in N.E.Mexico

The Cupido-Sligo reef front, borders a large Lower Cretaceous platform which encircles the northern rim of the Gulf of Mexico basin. The platform strata comprise the Coahuila Group (Neocomian to Mid Aptian in age), and consist of about 1000 m of cyclic restricted marine carbonate facies bordered by a reef, and/or grainstone rim (Cupido Fm). The platform facies progrades out from around the Coahuila block over the underlying shaly ammonite-bearing limestone (Taraises Fm), to black, cherty, rhythmic-bedded, pelagic lime, (Tamaulipas Inferior Fm.). One can trace the outcropping Cupido reef, using new satellite photos, from north of Monterrey southward to the town of Galeana, west of Linares, along an east-facing front. The relation of the reef trend of the Coahuila Block is most strikingly indicated by the sharp westward bend at Galeana.The sinuous reef front path is controlled only by the Coahuila Block and not by the other Upper Jurassic uplifts caused by Early Mesozoic rifting. The east-facing Cupido reef front has patches of corals, red algae, sponges, and hydrozoans, and thick rudist limestone but in the transverse Parras range, to the west, the south-facing front has grainstone banks and follows a ramp profile. The great width of the platform (1100 km), and its slightly raised rim, restricted circulation and caused evaporite deposition in the northern Sabinas Basin.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas