Publication: The Global Boundary Stratotype Section and Point
(GSSP) for base of the Bathonian Stage (Middle
Jurassic), Ravin du Bès Section, SE France
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Publication Date
2009-12
Authors
Pavia, Giulio
Erba, Elisabetta
Guiomar, Myette
Henriques, María Helena Paiva
Lanza, Roberto
Mangold, Charles
Morton, Nicol
Olivero, Davide
Tiraboschi, Daniele
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International Union of Geological Sciences
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Abstract
The Bathonian GSSP is defined at the base of limestone
bed RB071 in the Ravin du Bès Section, Bas-Auran
area, southern Subalpine Chains (France). This section
satisfies most of the erquirements recommended by the
International Commission on Stratigraphy. The exposure
extends over 13 m in thickness. No vertical biofacies,
ichnofacies or taphofacies changes, stratigraphic gaps
or hiatuses have been recorded at the Bajocian-Bathonian
transition. Structural complexity, synsedimentary and
tectonic disturbances, or important alterations by
metamorphism are not relevant constraints. There is a
well-preserved, abundant and diverse fossil record, with
key markers (ammonites and nannofossils). The base of
Bathonian Stage and Zigzag Zone corresponds to the first
occurrence level of Gonolkites convergens Buckman that
coincides with the first occurrence of Morphoceras
parvum Wetzel. Calcareous nannofossils are present in
all beds. The GSSP is below the Tethyan calcareous
nannofossil NJT10b/11 zonal boundary (lowest
Watznaueria barnesiae) and above the Bo real nannofossil
NJ10/11 boundary (lowest Pseudoconus enigma).
Regional analyses of sequence stratigraphy and
manganese chemostratigraphy are available. Spectral
gamma-ray data corroborate interpretation of an Early
Bathonian deepening half-cycle of second order. The criteria of accessibility, conservation and protection are
assured by the “Réserve Naturelle Géologique de Haute
Provence”. The Cabo Mondego Section (Portugal) is the
Bathonian auxiliary section and point (ASSP) .T he
proposal was voted by the Bathonian Working Group in
December, 2007, and by the International Subcommission
on Jurassic Stratigraphy in March, 2008, approved by
the ICS in June 2008, and ratified by the IUGS in Ju,ly
2008.