Formal proposal for the Bathonian GSSP (Middle Jurassic) in the Ravin du Bès Section (Bas-Auran, SE France)

Abstract

The Bathonian Global Stratotype Section and Point (GSSP) is proposed at the base of limestone bed RB071 (bed 23 in Sturani 1967) in the Ravin du Bes Section (43057' 38" N, 6° IS' 55" E), Bas-Auran area, "Alpes de Haute Provence" French department. The Ravin du BesSectioll , as formal candidate GSSP for the base of the Bathonian Stage, satisfies most of the requirements recommended by the International Commission on Stratigraphy: 1) The ex posure extends over 13 m in thickness. At the Bajocian-Bathonian transition, no vertical (bio-, ichno-or tap ho-) facies changes, condensation, stratigraphic gaps or hiatuses have been recorded. Structural complexity, synsedimentary and tectonic disturbances, or important alterations by metamorphism are not relevant constraints. 2) There is a well-preserved, abundant and diverse fos sil record across the boundary interval, with key markers (ammonites and IntroductionThe present paper corresponds to part of the scientifIc dossier recently prepared by several specialists and sent to all mem bers of the Bathonian Working Group (International Subcom mission on Jurassic Stratigraphy, November 2007), in order to achieve the formal ballot on the selection and proposal of the Global Stratotype Section and Point (hereafter GSSP The Bathonian Working Group (BtWG) was established in 1984, during the 1st International Symposium on Jurassic Stratigraphy in Erlangen, in order to improve the geologic data relative to the Bajocian/Bathonian boundary. The Bas-Auran section was first proposed as stratotype in a presentation to the Luxembourg II (1967) Colloquium by Torren� but not pub lished until 1974lished until (Morton 1974Torrens 1974a Torrens , b, 1987 Torrens , 2002 fig. 8; pI. 19, fIgS. 1-2) are the index species, respectively, of the Bathonian basal zone and subzone. The Zigzag Zone was distinguished from the underlying Parkinsoni Zone by Oppel (1857Oppel ( . p. 579. 1862. and later assigned to the "Bath-Gruppe·· (Oppel 1865. p. 309) in a discussion of the section at "Mon tagne de Crussol" in the Ardeche (France). The Convergens Subzone was mentioned by Maubeuge (1950, p. 4), based on the "Convergens horizon" that was used in letters by Arkell (1951-59. p.10; 1956. p. 62). The Bajocian/Bathonian bound ary established between the Parkinsoni and Zigzag zones was recommended at the two congresses denominated "Colloque du Jurassique" held in Luxembourg in 1962(Rioult 1964 Tor rens 1965) and 1967(Torrens 1974a. The localities of Bath (England) and the "Montagne de Crussol" (France), however, have been considered quite unsuitable for a typological defini tion of the Bathonian Stage, because they are condensed sec tions with discontinuous and lenticular beds (Torrens 1974a(Torrens , b, 2002Page 1996b). After the publication of Sturani (1967) (Sturani 1967). The Parvum Sub zone has been proposed by Mangold (1990) to denote the first Bathonian subzone of the Zigzag Zone in the Sub-Mediter ranean Province, equivalent to the Convergens Sub zone of the Northwest European Province...

New species of Franchia and Protozigzagiceras (Ammonoidea, Middle Jurassic): the phyletic origin of Zigzagiceratinae

“…; Fernandez‐Lopez ; Fernandez‐Lopez et al . , ; Pavia et al . ), these ontogenic modifications of zigzag‐states in Early Bathonian zigzagiceratins of the western Tethys represent successive, derived or apomorphic conditions (Gould , ; Dommergues et al .…”

“…3, figs 11, 12) and Fernandez‐Lopez et al . , fig. 6b) is refigured here in Figure B–C, magnified in Figure B–C, from level 12 in Sturani () and RA033 in Pavia et al .…”

“…3, figs 6, 7, 9–12; Fernandez‐Lopez et al . , fig. 6b), to the Iranian platform system (Shafizadeh and Seyed‐Emami , figs 10, 11; Shams and Seyed‐Emami ).…”

“…Fernandez‐Lopez et al . () formally proposed the Rabin du Bès Section as the GSSP of the Bathonian, and synthesized the regional biochronostratigraphical scales available for the Bajocian–Bathonian boundary. The Bathonian GSSP in the Ravin du Bès Section was approved by the International Commission of Stratigraphy (ICS) in June 2008 and ratified by the International Union of Geological Sciences (IUGS) in July 2008 (Fernandez‐Lopez et al .…”

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

“…This paper summarizes relevant results published by specialists (Fernández-López et al, 2009) and incorporates comments and responses of the Bathonian Working Group and International Subcommision on Jurassic Stratigraphy ballots (2007)(2008) on the formal proposal for the Bathonian GSSP (Middle Jurassic) in the Ravin du Bès Section (Bas-Auran, SE France). The proposal was accepted by the International Commission on Stratigraphy (June, 2008) and ratified by the International Union of Geological Sciences in July, 2008.…”