Response of calcareous nannofossils to the Paleocene-Eocene thermal maximum; observations on composition, preservation and calcification in sediments from ODP Site 1263 (Walvis Ridge, SW Atlantic)

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doi: 10.1016/j.marmicro.2008.07.002
Author(s): Raffi, Isabella; De Bernardi, Bianca
Author Affiliation(s): Primary:
Universita degli Studi Gabriele d'Annunzio di Chieti-Pescara, Dipartimento di Geotecnologie per l'Ambiente e il Territorio, Chieti, Italy
Universita degli Studi di Milano, Italy
Volume Title: Marine Micropaleontology
Source: Marine Micropaleontology, 69(2), p.119-138. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0377-8398 CODEN: MAMIDH
Note: In English. Based on Publisher-supplied data; includes appendix
Summary: In this study we present the results of a detailed analysis on calcareous nannofossil assemblages from sediment cores of ODP Site 1263 (Southern East Atlantic, Walvis Ridge). This section represents one of the few complete deep-sea sections that document the Paleocene-Eocene Thermal Maximum (PETM) in the pelagic realm. The PETM transient event was characterized by a brief, but intense interval of global warming, a global negative carbon isotope excursion (CIE), and widespread dissolution of seafloor carbonate sediments. Paired analysis at polarizing light microscope (LM) and Scanning Electron Microscope (SEM) documents the different "behavior" of nannofossils through the different phases of the PETM, at the onset of CIE, within the CIE, and during the recovery interval. The presence of anomalous specimens and morphotypes within some nannofossil taxa, recorded during previous LM high resolution analyses, has been further investigated in selected samples at the SEM. Besides the known representatives of the CIE-PETM "excursion nanno-flora", as Rhomboaster calcitrapa group and Discoaster anartios, the analysis revealed the presence of peculiar morphotypes of Fasciculithus and deformed specimens of Discoaster nobilis group, Discoaster mediosus and Discoaster multiradiatus that are considered related to the anomalous amount of CO2 in the ocean-atmosphere system during the early phase of PETM. Comparative analyses were performed in few selected samples from other PETM sections located at different latitudes in the Atlantic and Pacific oceans. Although the anomalous geochemical conditions during the PETM-CIE interval seem to have had some influence on the nannofossil production, calcification and assemblage composition, it results that local productivity together with post depositional (diagenetic) conditions were additional important controlling factors on nannofossil assemblages. Preliminary data from Eocene Thermal Maximum 2 (ETM2 or Elmo) suggest that nannofossil malformations are not exclusive of the PETM, and are associated to other episodes of perturbation of the C cycle. Abstract Copyright (2008) Elsevier, B.V.
Year of Publication: 2008
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Algae; Assemblages; Atlantic Ocean; Calcification; Carbon; Carbon cycle; Cenozoic; Eocene; Geochemical cycle; Leg 208; Microfossils; Nannofossils; ODP Site 1263; Ocean Drilling Program; Paleocene; Paleocene-Eocene Thermal Maximum; Paleoclimatology; Paleogene; Plantae; Preservation; SEM data; South Atlantic; Tertiary; Walvis Ridge
Coordinates: S283200 S283200 E0024700 E0024700
Record ID: 2009017178
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands