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Episodes 2009; 32(4): 222-248

Published online December 1, 2009

https://doi.org/10.18814/epiiugs/2009/v32i4/001

Copyright © International Union of Geological Sciences.

The Global Boundary Stratotype Section and Point (GSSP) for base of the Bathonian Stage (Middle Jurassic), Ravin du Bès Section, SE France

Sixto Rafael Fernández-López1, Giulio Pavia2, Elisabetta Erba3, Myette Guiomar4, Maria Helena Henriques5, Roberto Lanza2, Charles Mangold6, Nicol Morton7, Davide Olivero6 and Daniele Tiraboschi3

1Departamento y UEI de Paleontología, Facultad de Ciencias Geológicas (UCM) e Instituto de Geología Económica (CSIC-UCM), 28040- Madrid (Spain). E-mail: sixto@geo.ucm.es
2Dipartimento di Scienze della Terra, via Valperga Caluso 35, 10125-Torino (Italy). E-mail: giulio.pavia@unito.it, roberto.lanza@unito.it
3Dipartimento di Scienze dalla Terra “Ardito Desio”, Università degli Studi di Milano, Via Mangiagalli, 34, 20133-Milano (Italy). E-mail: elisabetta.erba@unimi.it, daniele.tiraboschi@unimi.it
4Centre de géologie – Parc Saint-Benoît, 04000-Digne-les-bains (France). E-mail: myette.guiomar@libertysurf.fr
5Departamento Ciências da Terra e Centro de Geociências, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3000-272 Coimbra (Portugal). E-mail: hhenriq@dct.uc.pt
6Université Claude Bernard, Lyon-1,UFR des Sciences de la Terre et CNRS, UMR 5125, 27–43, bd du 11-Novembre-1918, 69622-Villeurbanne cedex (France). E-mail: David.Olivero@univ-lyon1.fr
7Le Chardon, Quartier Brugière, F-07200 Vogüé (France). E-mail: nicol.morton@orange.fr

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 requirements 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 Boreal 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). The 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 July, 2008.