STRATIGRAPHY OF CRETACEOUS RADIOLARIAN CHERTS OF CUBA (ABSENT)

AIELLO IVANO WALTER ¹, CHIARI MARCO ², PRINCIPI GIANFRANCO ³, GARCIA DORA ⁴

presenter's e-mail: iaiello@mlml.calstate.edu

1 - Moss Landing Marine Laboratories, Moss Landing, CA, 95039-9647, USA
2 - CNR, Istituto di Geoscienze e Georisorse, Florence, 50121, Italy
3 - Università di Firenze, Dipartimento di Scienze della Terra, FIorence, 50121 Italy
4 - Instituto de Geologia y Paleontologia, 11000 Habana, Cuba

We present the results of a stratigraphic and biostratigraphic survey performed on radiolarian cherts of the orogenic belts of central and western Cuba. The radiolarian cherts of Cuba occur in both deep-water continental-margins, and in the ophiolite units. In the continental margin sequence of Rosario (Guaniguanico Terrane, western Cuba), the radiolarian cherts of the Santa Teresa Formation overlie Lower Cretaceous basinal sediments that are either composed of limestones (Artemisa Formation), or sandstones (Polier Formation). In general, the chert beds are green or dark grey, and less frequently red, and they show sedimentary structures such as low angle lamination, and radiolarian tests gradation that suggest redeposition either by fine-grained turbidites or by bottom-currents winnowing. Biostratigraphic data indicate that radiolarians deposition occurred between the Aptian and the Cenomanian. The allochtonous ophiolite nappe that in western Cuba overlies the Guaniguanico Terrane (Northern Ophiolitic mélange) also contains radiolarian cherts, which in some of the exposures occur interbedded with basalts and dark limestones. The radiolarian chert beds are usually red, and they occur alternated with thick claystone interlayers. Their age ranges between the Albian and the Cenomanian. Thus these ophiolite cherts are almost coheval with the continental margin cherts of the Santa Teresa Formation. Finally, the biostratigraphic analysis of an outcrop of red radiolarian cherts that occur within a folded ophiolite unit near Santa Clara (central Cuba), indicates a Lower Cretaceous age for these rocks and, in particular, radiolarians deposition is not younger than Aptian.
In summary, the our biostratigraphic and lithostratigraphic data suggest that:
1) The age of the ophiolites of western Cuba is probably not younger than Cenomanian;
2) The radiolarian cherts of continental margin and ophiolite units of western Cuba may be coeval, and thus a common paleogeographic origin for these rocks is possible;
3) The ophiolite unit of Santa Clara (Central Cuba) formed before Albian, and therefore they might be older than the ophiolites of western Cuba.

ACCEPTED as Poster Presentation
in session: "G20.11 - Caribbean plate tectonics"