Lower-middle Eocene benthic foraminifera from the Fortuna Section (Betic Cordillera, southeastern Spain)

摘要

Benthic foraminifera were studied as part of an investigation of the Fortuna Section (Betic Cordillera, Southeastern Spain), undertaken to document a candidate section for the Global Stratotype Section and Point (GSSP) for the base of the Lutetian Stage (Ypresian/Lutetian boundary). Benthic foraminiferal assemblages in this section are mostly dominated by calcareous taxa (～50-96%) and by infaunal morphotypes (～55-88%). The most abundant calcareous taxa are Globobulimina species, Aragonia aragonensis, Cibicidoides species, Osangularia dominicana, and various Lenticulina species. The most common agglutinated species are Clavulinoides angularis, Gaudryina arenata, and Thalmannammina subturbinata. Globobulimina species, A. aragonensis, and C. angularis show strong fluctuations in relative abundances, with a pronounced peak in the relative abundances of Globobulimina species and Aragonia aragonensis, and low species richness across the Ypresian/Lutetian boundary. The occurrence of several peaks in abundance of Globobulimina species suggests that food supply to the benthos fluctuated, and the single peak in abundance of A. aragonensis across the Ypresian/Lutetian boundary might be indicative of a hyperthermal event. Paleodepths inferred from the assemblages range from lower upper bathyal for the lower part of the section to sublitoral for its upper part, and there is no evidence for a sea-level fall at the Ypresian/Lutetian boundary. We selected 82 out of 175 benthic foraminiferal taxa for detailed taxonomic description, based on their relative abundances and/or paleoecological or paleobathymetrical importance.