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

Fernández-López, Sixto R.; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Henriques, Maria Helena; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Tiraboschi, Daniele

doi:10.18814/epiiugs/2009/v32i4/001

Cited by 31 publications

(14 citation statements)

References 139 publications

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“…), the Bathonian in 2008 (Bas‐Auran, Haute‐Provence, France; Fernández‐López et al . ), the Hettangian in 2007 (i.e. basal Jurassic; Kuhjoch, Northern Calcareous Alps, Austria; Hillebrandt et al .…”

Section: Standardizing Stratigraphical Nomenclature Gssps and The Fumentioning

confidence: 99%

From Oppel to Callomon (and beyond): building a high-resolution ammonite-based biochronology for the Jurassic System

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2017

LET

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By 1849, Alcide d'Orbigny had proposed a very modern looking global subdivision of a Jurassique ‘System’, into a sequence of 10 étages. D'Orbigny's stages were based on a basic biostratigraphical framework, but there were still a number of issues with its actual demonstrable applicability internationally. In 1856, Albert Oppel took d'Orbigny's framework and, as stated by W.J.Arkell in 1933, ‘breath[ed] new life into it…placing the whole science of stratigraphical geology on a new footing’. Oppel recognized eight ‘Etagen’, divided into a sequence of ‘zones’ which he considered to be time‐related to correlation units of theoretically universal application – a very clear and unambiguous statement of what now would be considered to be chronostratigraphical practice. Subsequently, evolution of Jurassic stratigraphy had, by the end of the 18th century led to S.S Buckman's high‐resolution ammonite correlation schemes using hemera – essentially the same as modern biohorizons. Although some of this detail was subsequently lost in his syntheses, from around 1933–1956, W.J. Arkell took many pre‐existing ‘zonal’ schemes and began to develop global ‘standard’ ammonite correlation schemes – again explicitly chronostratigraphical. Nevertheless, the potential for very high‐resolution ammonite‐based correlation schemes – with a resolution of only around 100,000 or less – was soon rediscovered and promoted by J.H. Callomon and by a very active ‘French School’. Despite all this activity, however, we still have not quite realized the ordered stratigraphical dreams of Oppel and his successors. Of the 11 stages now formally recognized within the Jurassic, four still do not have a ratified GSSP, and within the entire system, there still appear to be no formal agreements on what really are the ‘standard’ zones for each stage. Crucially, however, confusion is still widespread as to the ‘meaning’ of these zones – Jurassic ‘Standard Zones’ are chronozones not biozones – they have been explicitly so since Oppel's day, and as the stratigraphical building blocks of all ‘modern’ Jurassic stages, they must still be.

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Section: Standardizing Stratigraphical Nomenclature Gssps and The Fumentioning

confidence: 99%

From Oppel to Callomon (and beyond): building a high-resolution ammonite-based biochronology for the Jurassic System

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2017

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“…The sedimentary succession is represented by marine deposits of Late Toarcian to Kimmeridgian age (Ruget-Perrot, 1961). Cabo Mondego is the Global Stratotype Section and Point (GSSP) for the Aalenian/Bajocian boundary (Pavia and Enay, 1997) as well as the Auxiliary Stratotype Section and Point (ASSP) for the Bajocian/Bathonian boundary (Fernandez-Lopez et al, 2009). Numerous ammonites have been collected throughout the succession, allowing for the establishment of a precise biostratigraphical framework (Fernandez-Lopez et al, 1988;Henriques et al, 1994).…”

Section: Cabo Mondegomentioning

confidence: 99%

Middle Jurassic coccolith fluxes: A novel approach by automated quantification

Suchéras-Marx¹,

Giraud²,

Mattioli³

et al. 2014

Marine Micropaleontology

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International audienceCoccolithophores, major pelagic carbonate producers, underwent important changes during the latest Aalenian–Early Bajocian (ca. − 170 Ma, Middle Jurassic). Specifically, a new genus called Watznaueria diversified and started dominating the coccolith assemblages. While this change in the coccolith assemblages is already known, the impact on coccolith absolute abundances and fluxes is still misunderstood. Here we tested for the first time on Mesozoic deposits an automated counting method using the SYRACO system, and then compared these results with a classic counting method. Two neural networks were created based on the shape, birefringence and size of coccoliths, the first of which contained only one class and the second of which was composed of six classes. Based on the morphological criteria used for the neural networks, coccoliths were not identified at the species level. We quantified coccolith absolute abundances and estimated fluxes for the latest Aalenian–Early Bajocian in two well-dated and correlated sections, Cabo Mondego in Portugal and Chaudon-Norante in France. There is a strong linear correlation between classic and automatic counting (r > 0.8) supporting the latter as a reliable method for coccolith absolute abundance and flux quantification. In spite of under- or over-estimation by automatic counting with respect to classic counting, the absolute abundance stratigraphic trends are remarkably similar. Under- or over-estimation may be reduced by further technical improvements such as automatic focus. At Cabo Mondego, coccolith fluxes increased from 0.2 × 109 coccoliths/m2/yr in the latest Aalenian to 700 × 109 coccoliths/m2/yr in the middle of the Laeviuscula ammonite Zone (Early Bajocian), remaining high for the rest of the Early Bajocian. At Chaudon-Norante, a similar trend was observed. This coccolith flux increase is therefore considered to be a supra-regional event matching an important δ13CBulk carbonate positive excursion. The carbon isotopic positive excursion, along with the onset of radiolarian sedimentation and coccolith fluxes is related to a gradual increase in the fertility of the oceans during the Early Bajocian and is likely associated with warmer and more humid climates and associated enhanced continental weathering

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“…Palaeogeography modified from Fernandez‐Lopez et al . (), Fernandez‐Lopez and Chong Diaz () and Golonka (); palaeobiogeographical units according to Westermann ().…”

Section: Palaeobiogeographical and Evolutionary Implicationsmentioning

confidence: 99%

“…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 . ).…”

mentioning

confidence: 97%

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

Fernández-López

Pavia

2013

Palaeontology

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

Cited by 31 publications

References 139 publications

From Oppel to Callomon (and beyond): building a high-resolution ammonite-based biochronology for the Jurassic System

From Oppel to Callomon (and beyond): building a high-resolution ammonite-based biochronology for the Jurassic System

Middle Jurassic coccolith fluxes: A novel approach by automated quantification

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

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