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OLIGOCENE–MIOCENE PALYNOMORPH ASSEMBLAGES FROM EASTERN VENEZUELA

Departamento de Geología, C.I.C.E.S.E., Km 107 Carretera Tijuana-Ensenada, Ensenada, Baja California, 22860, México and CICESE, Geology Department, P.O. Box 434843, San Diego, CA 92173-4843. e-mail: jhelenes{at}cicese.mx

DIANA CABRERA

PDVSA INTEVEP, Apartado Postal 76343, Caracas, 1070A, Venezuela

Palynological analyses of several subsurface sections in eastern Venezuela, show varied and abundant Oligocene–Miocene palynomorphs overlying a Cretaceous–Oligocene unconformity. Two palynomorph assemblages are recognized in the Cretaceous interval, and two more in the Tertiary strata.

The Cretaceous strata contain the spores Foveotriletes margaritae, Buttinia andreevi and elateres of Ariadnasporites sp., together with the dinoflagellates Dinogymnium, Andalusiella, Cerodinium, Senegalinium, and locally Isabelidinium and Odontichitina. The terrestrial assemblage represents the undifferentiated Auriculiidites reticularis (Campanian to lower Maastrichtian) to Crassitricolporites subprolatus (Maastrichtian) zones, and the Proteacidites dehanii (Maastrichtian) zone of Müller et al. (1987), while the dinoflagellates indicate a Campanian to Maastrichtian age, depending on the location within the area.

The lowermost Tertiary rocks are late Oligocene in age and contain the terrestrial palynomorphs Cicatricosisporites dorogensis, Jandufouria seamrogiformis, Polypodiisporites usmensis and Mauritiidites franciscoi, together with the dinoflagellates Cordosphaeridium spp., Polysphaeridium congregatum, Homotryblium spp. and Tuberculodinium vancampoe. The terrestrial assemblage represents the Magnastriatites–Cicatricosisporites dorogensis zone of Müller et al. (1987), while the dinoflagellates indicate a late Oligocene age.

Higher in the section, the early Miocene strata contain the pollen Psilatricolporites pachydermatus, P. maculosus, Bombacacidites brevis and Bombacacidites noremii together with the dinoflagellates Cribroperidinium tenuitabulatum and Diphyes latiusculum. The terrestrial assemblage represents the Verrutricolporites rotundiporis–Echidiporites barbeitoensis zone of Müller et al. (1987), and the concurrent presence of the dinoflagellates indicate an early Miocene age.