International Geologiical Congress - Oslo 2008

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HPS-07 Pliocene-Pleistocene correlations and global change

 

The case for the undecapitated Neogene

 

Frits Hilgen, Utrecht University (Netherlands)
Marie-Pierre Aubry, Rutgers University (United States)
Bill Berggren, Rutgers University (United States)
Brian McGowran, The University of Adelaide (Australia)
John Van Couvering, American Museum of Natural History (United States)
Fritz Steininger, Senckenberg Naturmuseum (Germany)
 

 

In GTS2004, the Quaternary was deliberately eliminated as a formal chronostratigraphic unit from the standard Geological Time Scale while the Neogene extended to the Recent. This extended Neogene concept was not a spontaneous and new development but represented the fundamental usage in the study of the (deep) marine stratigraphic record, upon which modern stratigraphy is based.

The original definition of the Neogene incorporated faunas from stratigraphic units that are now considered (late) Pleistocene in age. The concept of the Neogene that included the Pleistocene and Recent was incorporated in a number of time scales over the years, and was eventually adopted as a formal term for the late Cenozoic by researchers who began to explore the deep marine record in the 20th century.

The concept of the extended Neogene lies behind the (in)famous 3rd recommendation for defining the Pliocene-Pleistocene boundary that came out of the London 1948 congress. It also underlies the letter-numerical codification for all standard microfossil zones up through the Recent as N-, or Neogene, zones. In addition the extended Neogene, as a formal chronostratigraphic unit, was very widely adopted by the DSDP and ODP scientific community, and has thus entered most of the current textbooks on historical geology.

Without any argument, the continuous deep marine archive is now the basic framework in particular for Cenozoic historical geology, and its data are routinely considered to be the most suitable for subdividing the standard Geological Time Scale. The understanding of the dominantly continental record of the Quaternary has, in fact, been revolutionized by the study of the marine Neogene, which over the last decades has led to a stable astronomical-tuned time scale with a fully integrated magnetobiochronostratigraphic framework via first-order correlations. This innovative approach resulted in a revaluation of the unit stratotype concept, in the potential introduction of orbital-induced cycles as chronozones, and in the intercalibration of astronomical and radio-isotopic time.

It seems clear to us that a compromise is needed to resolve the ongoing controversy about the formal definitions of Neogene and Quaternary. The most plausible and logical solution would be to create a separate chronostratigraphic status for the Quaternary, while maintaining the extended Neogene. Such a solution would do justice to the two main traditions in stratigraphy in the so important youngest part of our time scale.

By contrast, the agenda of the Quaternary community completely ignores the Neogene community's point of view. Moreover, it would represent an unwelcome conservatism by overlooking first-order (marine) chronostratigraphic principles while emphasizing interpretations of paleoclimatic effects, and by totally neglecting the revolution in chronostratigraphic philosophy and approach that came out of the - undecapitated - Neogene and its long-standing marine tradition.

 

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