MICROPALEONTOLOGICAL DATING OF THE COLLISION BETWEEN THE NORTH-AMERICAN PLATE AND THE GREATER ANTILLES ARC IN WESTERN CUBA

The timing of collision between the Cretaceous Greater Antilles volcan ic are and the Jurassic-Cretaceous North American passive margin. is p oorly constrained. Previous age estimates range from Late Cretaceous t o late Eocene. This wide range results from uncertainty of tectonic re constructions, lateral migration. of tectonic activity and paucity of accurate age information. We present nannofossil and foraminiferal bio stratigraphic data from outcrops and sections in western Cuba, synthes ized with previous age information, and propose a latest Paleocene to early Eocene age (nannofossil Zones NP9 to NP13; 50-56 m.a.) for termi nal collision in western Cuba. This age estimate is obtained from the biostratigraphy of pre- and syn-collisional sedimentary rocks in the G uaniguanico tectonic unit, part of the original North American Plate, and syn- and post-collisional sedimentary rocks in the Bahia Honda and Los Palacios tectonic units, which were part of the Greater Antilles Are. Our data indicate that the collision. took place over 20 m.y. aft er the extinction of the arc, and, therefore, that these events were u nrelated. Most outcrops studied have a limited stratigraphic extent, p reventing the delineation of complete zonal units. However we show tha t sub-zonal biostratigraphic resolution can be obtained using the pres ence and absence of numerous non-zonal markers.