Late Eocene to Oligocene events: Molino de Cobo, Betic Cordillera, Spain

• Eustoquio Molina ^[1] ; Gerta Keller ^[2] ; Marina Madile ^[3]
  1. [1] Universidad de Zaragoza

     Universidad de Zaragoza

     Zaragoza, España

     
  2. [2] Princeton University

     Princeton University

     Estados Unidos

     
  3. [3] University of Florence

     University of Florence

     Firenze, Italia

     

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• Localización: Revista española de micropaleontología, ISSN 0556-655X, Vol. 20, Nº. 3, 1988, págs. 491-514
• Idioma: inglés
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• Resumen

  • Quantitative analysis of upper Eocene to Oligocene planktonic foraminifers and calcareous nannofossils in the molino de Cobo section, Betic Cordillera, Spain indicate three major extinction events: 1) in the upper Eocene at the extinction of Globigerapsis index, 2) at the Eocene-Oligocene boundary and 3) at the lower/upper Oligocene boundary. The Globigerapsis index extinction event in this area coincides with the dramatic abundance decline of the discshaped discoasters (D. saipanensis, D. barbadiensis). This faunal and floral assemblage change coincides with a carbonate dissolution interval.

    The Eocene-Oligocene boundary extinction event involves five planktonic foraminiferal species, which contrary to common belief did not go extinct simultaneously, but stretched out over a 3m interval. This extinction event is probably related to the isotopic enrichment that signals the development of the psychrosphere, or two layer ocean with cold bottom and warm surface water. The lower/upper Oligocene faunal turnover event involves the extinction of surviving Eocene species and the evolution of late Oligocene to Miocene species. A short hiatus may be present at this interval. This faunal turnover is most likely related to global cooling and a major sea level drop.