ABSTRACT

The "Carrillo Puerto Formation" of the eastern Yucatan peninsula is a biostratigraphic unit containing fossils ranging in age from Miocene to Holocene. Recent field work suggests the formation can be divided into several genetic units. Each unit was deposited during high stands of the Caribbean Sea, which have periodically inundated portions of the peninsula, and each is capped by a subaerially weathered crust (caliche) formed during low stands of sea level. Similar Quaternary caliche horizons are recognized in Florida, the Bahamas and Barbados. Comparisons between these horizons and those of the Yucatan Peninsula provide new information on the recent geologic history of the eastern platform margin.

At least five marine transgressions of late Tertiary to Holocene age are recorded in the rocks of eastern Quintana Roo. Along the coast, Holocene sediments and reefs overlie calichified upper Pleistocene (Sangamon Interglacial) beach-plain grainstones and coral-reef limestone. Underlying the upper Pleistocene limestone and cropping out farther inland is another Pleistocene (?) grainstone. Underlying this and exposed still farther inland is a unit of mollusk wackestones, packstones and grainstones with coral boundstones. Still farther inland, the oldest unit exposed in Quintana Roo is a highly leached coral head and mollusk wackestone.

The onlap of successive units has decreased with each transgression resulting in a seaward shift of platform grainstones, wackestones and reefal limestones. Carrillo Puerto limestones of eastern Quintana Roo built progressively upward and outward over a block-faulted continental shelf margin during the late Tertiary and Quaternary.