2026-10-15T10:30:46Z https://oai.datacite.org/oai

doi:10.1594/pangaea.755383 2024-07-20T17:46:32Z PANGAEA PANGAEA.REPOSITORY

Late Eocene to early Oligocene calcareous nannofossils of ODP Holes 114-699A and 114-703A Madile, Marina Monechi, Simonetta PANGAEA 1991 Issued: 1991 doi:10.2973/odp.proc.sr.114.185.1991 Drilling/drill rig Leg114 Joides Resolution Ocean Drilling Program (ODP) Calcareous nannofossil assemblages were studied from Sites 699 and 703, drilled during ODP Leg 114 to the west and east, respectively, of the Mid-Atlantic Ridge in the subantarctic South Atlantic Ocean. Recovery at the two sites consists of an almost continuous sequence of upper Eocene-lower Oligocene sediments. This study describes the calcareous nannofossil assemblages at the transition between the Eocene and Oligocene and correlates these assemblages with those described in lower latitude sections. Quantitative analyses were performed on several important taxa in order to improve the biostratigraphic resolution and permit some paleoenvironmental interpretations. Several discrepancies were noted between the two sites and between the Eocene and Oligocene assemblages. The Eocene assemblages show a great number of species and warmer water conditions; the early Oligocene assemblages are less diversified and are indicative of cooler conditions. The Eocene/Oligocene boundary was not defined by planktonic foraminifers because of the strong dissolution, poor recovery, and drilling disturbances. On the other hand, the calcareous nannofossil assemblage allowed recognition of the interval where the Eocene/Oligocene boundary can possibly be placed. Supplement to: Madile, Marina; Monechi, Simonetta (1991): Late Eocene to early Oligocene calcareous nannofossil assemblages from sites 699 and 703, subantarctic South Atlantic Ocean. In: Ciesielski, PF; Kristoffersen, Y; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 114, 179-192 en Collection Supplementary Publication Series of Datasets application/zip Creative Commons Attribution 3.0 Unported https://creativecommons.org/licenses/by/3.0/legalcode