Abstract
Abstract Five paleoenvironmental intervals (interval 1-interval 5) are established in the late Paleogene-early Neogene of the Ocean Drilling Program (ODP) Site 959 (Hole 959A), Cote d'Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic. The intervals are based on dinoflagellate cyst and palynofacies analyses of 30 samples covering a 273.3-m interval. We observed an abundance of the Filisphaera group (Filisphaera filifera and Bitectatodinium tepikiense) which is interpreted as an Arctic migration to equatorial regions during a narrow interval in the Early Oligocene (early Rupelian). In addition, we document one hiatus within interval 3 in the Early Miocene (Aquitanian). The dominance of typically restricted marine species of the Polysphaeridium group (Homotryblium plectilum and Polysphaeridium zoharyi) at several horizons in the open-oceanic sediments of ODP Hole 959A appear to be very distinctive events. Upon integrating dinoflagellate cyst data with prior lithologic and microfossil data, we interpret these dominance events as being due to offshore transportation by turbidity currents (intervals 1 and 2), hiatus event (interval 3), or hyperstratification conditions (intervals 3 and 4). In addition, the dominance of Cribroperidinium spp. (C. giuseppei and C. tenuitabulatum) in the upper part of the section within paleoenvironmental interval 5 is suggestive of cold-water masses during a strong upwelling period in the latest Early Miocene (Burdigalian). The general abundance of amorphous organic matter alongside the dinoflagellate cyst assemblage supports an outer neritic-oceanic depositional environment for the studied site. The consistent occurrence of degraded phytoclasts in the sediments also suggests fluvial outflows to this offshore site.
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