Integrated biozonation based on palynology and ostracods from the Neogene of Solimões Basin, Brazil

Abstract Biostratigraphic analysis integrating spores-pollen and ostracods from boreholes 1AS-8-AM and 1AS-7D-AM, at Atalaia do Norte, Amazonas state, Brazil, allowed to infer Early to Late Miocene for studied sequences. Five palynological zones previously proposed for the Solimoes Formation were identified: Verrutricolporites (Early Miocene), Psiladiporites–Crototricolpites (late Early to early Middle Miocene), Crassoretitriletes (Middle Miocene), Grimsdalea (late Middle to Late Miocene), and Asteraceae (Late Miocene). At the same time, four ostracods ( Cyprideis ) zones were identified but with limits modified: C. sulcosigmoidalis (late Early to early Middle Miocene); C. caraionae (late Middle to early Late Miocene); C. minipunctata (late Middle to Late Miocene); and C . cyrtoma (early Late Miocene). Furthermore, a new ostracod zone, Cyprideis paralela interval zone (Late Miocene), is formally proposed. Two main bioevents of Cyprideis radiation, related to marine incursions, have been identified: one at late Middle Miocene/early Late Miocene ( Grimsdalea zone) and another at Late Miocene ( Asteraceae zone). This study attests the viability and importance of using multiple microfossil for more accurate dating and correlation between basins.