Oxfordian–Berriasian Stratigraphy of the North American Paleomargin in Western Cuba<subtitle>Constraints for the Geological History of the Proto-Caribbean and the Early Gulf of Mexico</subtitle>

Abstract

Many models that attempt to interpret the regional geology of the Caribbean-Gulf of Mexico area share the handicap of paying little attention to precise data from Cuba despite its location at the North American-proto-Caribbean paleoboundary. The North American Mesozoic paleomargin crops out along northern Cuba, an area where many wells have encountered Jurassic and Lower Cretaceous rocks. In this chapter, we present a stratigraphic interpretation of the North American passive continental paleomargin recognized in the Guaniguanico mountains (western Cuba) and identify the main geological events recorded in their Oxfordian to Berriasian sections. We correlate these sections with other Mesozoic passive paleomargin sections in Cuba, including the Escambray and Isle of Youth metamorphic terranes. These sections and those in the southeastern Gulf of Mexico record early stages of the disintegration of Pangea in Mesoamerica and the early development of the southeastern Gulf of Mexico and westernmost Tethys (proto-Caribbean). In all, two main sequences can be distinguished: (1) a lower terrigenous one and (2) an upper marine carbonate sequence. The transition from terrigenous to carbonate sedimentation occured during the late middle Oxfordian in western Cuba (and possibly in the Escambray mountains of central Cuba). In Placetas zone of central Cuba, the terrigenous-carbonate transition spans from Kimmeridgian to Berriasian. Transgression occurred close to the Kimmeridgian–Tithonian boundary. Deeper depositional conditions started during the Tithonian along the paleomargin in northern Cuba. This event may be correlated with the beginning of the drowning and stepback of the small carbonate platforms developed in the southeastern Gulf. Spreading and rifting ceased in the southeastern Gulf of Mexico when the Yucatan block reached its present position in the earliest Cretaceous. The unconformity that records the change in tectonic setting is called the late Berriasian surface, but our reinterpretation of biostratigraphic data indicates that the age of generalized flooding is middle Berriasian. In middle and late Berriasian times, a belt of deep-water carbonates surrounded the northern margin of the proto-Caribbean (westernmost Tethys). Extensive carbonate banks developed on the Bahamas-Florida platform and surrounded the emergent Yucatan Platform.