MICROPLANCTON DE LA FORMACION ROCA DE LA PROVINCIA DE NEUQUEN

Abstract

Fossil microplankton has been studied from the Roca Formation of Neuquén Province. Previous studies of these sediments, in its foraminiferal part, gave a Lower Paleocene age (Mailhe, Malumian y Riccardi, 1967). In this paper have been studied five species of Deflandrea, one of Spinidinium and Scriniodinium, two of Hystricbospbaera (four varieties of Hystrichosphaera ramosa), two of Hystrichosphaeridium, one of Oligosphaeridium, Dipbyes, Tanyosphaeridium, Cordospbaeridium, Cleistospbaeridium, Adnatosphaeridium, Cyclonepbelium, Baltisphaeridium, Micrhystridium, Solisphaeridium, Palambages, Pteros permopsis and Chlamydophorella. The follcwing species are new: Spinidinium rallum, Deflandrea irmoecbinata, Scriniodinium (Scriniodinium) uerrucosum, Hystrichosphaera beterostylis, Cordosphaeridium tenuistriatum, Baltispbaeridium angulosum, and Solispbaeridium filamentosum. New combinations are: T anyosphaeridiun-magdalium (Drugg, 1967) and Cyclonephelium australis (Pothe de Baldis, 1966). The strat.graphical range of known species found in the assemblage studied oscillates between the Upper Cretaceous and the Eocene. The most probable age is the Danian.