Stratigraphic Constraints on the Late Jurassic–Cretaceous Paleotectonic Interpretations of the Placetas Belt in Cuba

Abstract

The Placetas belt in north-central Cuba consists of Late Jurassic–Cretaceous rocks that were highly deformed during the Paleocene to middle Eocene arc-continent collision. The Late Proterozoic marble and Middle Jurassic granite are covered by the shallow-marine arkosic clastic rocks of late Middle Jurassic(?) or earliest Late Jurassic(?) ages. These arkosic rocks may be older than the transgressive arkosic deposits of the Late Jurassic–earliest Cretaceous Constancia Formation. The Berriasian age of the upper part of the Constancia Formation in some outcrops at Sierra Morena and in the Jarahueca area does not confirm the Late Jurassic (pre-Tithonian) age of all deposits of this unit in the Placetas belt. The Tithonian and Berriasian ammonite assemblages are similar in the Placetas belt of north-central Cuba and the Guaniguanico successions in western Cuba. We conclude that in all paleotectonic interpretations, the Placetas, Camajuan, and Guaniguanico stratigraphic successions should be considered as biogeographically and paleogeographically coupled during the Tithonian and the entire Cretaceous. These successions could not have been separated by any large continental block and/or wide oceanic basin. The Tithonian-Berriasian ammonite assemblages reported from the Placetas belt and coeval assemblages known in Mexico are different; in particular, Suarites, Acevedites, and Kossmatia (characteristic Mexican genera) are unknown from the Tithonian sections of the Placetas belt. Moreover, the Early Cretaceous and Cenomanian deep-water formations of the Placetas belt do not contain deposits symptomatic of a presence of a nearby large landmass (Chortis Terrane?) to the south. Dissimilarities existing between the Huayacocotla remnant and the Guaniguanico (and Placetas) successions in Cuba are not consistent with the conclusion of some authors that the Jurassic and Early Cretaceous successions in western Cuba are nearly identical to those of San Pedro del Gallo Terrane remnants in east-central Mexico. Also, the composition of Late Jurassic ammonite and microfossil assemblages in western Cuba is not in agreement with the paleolatitudinal position of the Guaniguanico Terrane at 30N, close to the Pacific coast. Many authors accept interpretations linking the Placetas succession with the southern slope of the Bahamas and/or with the Proto-Caribbean basin floor. However, the stratigraphic record strongly suggests that only the southernmost Tithonian deposits of the Placetas succession (Sierra de Camajn) may represent the basinal section accumulated on the Proto-Caribbean oceanic floor. The original proximity or even continuity of the Late Jurassic–Cretaceous Placetas and Camajuan successions is probable on the basis of existing stratigraphic data.