Detrital zircon geochronology of Jurassic sandstones of western Cuba (San Cayetano Formation): Implications for the Jurassic paleogeography of the NW Proto-Caribbean

Clastic sediments of the early (?) to late Jurassic (Oxfordian) San Cayetano Formation of western Cuba are interpreted to reflect syn-rift sedimentation coeval with the breakup of Pangaea. This sedimentary unit is the oldest known in the Guaniguanico Mountains and Cuba. U-Pb SHRIMP dating of 19 detrital zircon grains from two samples of San Cayetano micaceous sandstone provided concordant ages ranging from similar to 398 to 2479 Ma. The oldest zircon population is of Paleoproterozoic age (similar to 2479 - 1735 Ma), but most zircons have early Mesoproterozoic and Grenvillian ages (similar to 1556 - 985 Ma), whereas still younger ages are Pan-African (561 Ma), Ordovician (451 Ma) and early Devonian (similar to 398 Ma). We discuss the possible origin of these zircons and conclude that the most likely source terrain(s) are Precambrian and early Paleozoic massifs in northern South America (Colombia and/or Venezuela) and the Yucatan Peninsula in Mexico. This is compatible with paleogeographic reconstructions of the Caribbean that imply that sediments of the San Cayetano Formation were still part of the disintegrating supercontinent Pangea in pre mid-Oxfordian time.