The Petroleum Potential and a Geodynamic Model for the Formation of Hydrocarbon Accumulations on the Southern Shelf of Cuba

摘要

All the oil fields of Cuba are localized within the accretionary prism, which forms the North Cuba fold and thrust belt, and immediately north of Jurassic-Neocomian ophiolites and Aptian-lower Campanian volcano-sedimentary rocks of the Zaza terrane (main constituents of the prism) thrust over the southern margin of the Late Mesozoic Florida-Bahamas carbonate platform. In the northern petroliferous province (Fig. 1) confined to a narrow coastal zone of northern Cuba, oil is largely generated by rocks of the relative autochthon represented by thick (up to 12 km) Jurassic-Neocomian shallow-water (shelf) carbonate and Aptian-Turonian terrigenous rocks characterized by high concentrations of organic matter and a high degree of its catagenetic transformation. The mechanism of hydrocarbon generation includes the progressing heating of underlying oil-generating sequences under the influence of the allochthon and geodynamic load of the nappe packet, which provide favorable environments for the formation of additional hydrocarbon portions and their squeezing out from source rocks and subsequent migration along faults into reservoirs in the upper parts of the thrust section. A viewpoint was shared by researchers until recently, that hydrocarbons were generated during the tectonic emplacement of the Northern Cuba fold and thrust belt in the Late Cretaceous-Paleogene or immediately after overthrusting accompanied by the opening of the adjacent Yucatan basin.