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Saint-André-les-Vergers, France

Pictet A.,Institute of Earth science | Delanoy G.,University of Nice Sophia Antipolis | Adatte T.,Institute of Earth science | Spangenberg J.E.,Institute of Earth science | And 5 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

A stratigraphic and depositional model, constrained by biostratigraphy, geochemistry, total phosphorus contents, and bulk-rock mineralogy, is proposed for lower Aptian sediments from the Languedoc platform in Ardèche, SE France. The upper lower Aptian is documented by the Chabert Formation (upper Deshayesites forbesi Zone to upper Dufrenoyia dufrenoyi Subzone), deposited on a discontinuity surface on top of the Urgonian platform, recording a first emersion phase and consecutive drowning event. The Chabert Formation starts with the marly Violette Member, which passes into crinoidal limestone of the Rocherenard Member. The top of this member is associated with a second discontinuity, recording a further drowning phase, which is followed by the deposition of the glauconitic and partly phosphatic Picourel Member (upper Deshayesites grandis to upper Dufrenoyia dufrenoyi Subzone). A third erosive phase is documented by a phosphatic conglomerate (upper Dufrenoyia furcata Zone), which represents a lag deposit derived from underlying sediments. The formation of this conglomerate was associated with a substantial emersion phase. This emersion was followed by a drowning event reworking the phosphatic conglomerate into the base of the upper Aptian black marls (Frayol Formation). The carbon-isotope record shows a negative excursion which coincides with the onset of the early Aptian oceanic anoxic Selli episode (OAE 1a) in the middle/upper part of the Deshayesites forbesi Zone. Emersion phases were an important factor implied in the formation of the sequence boundaries, which were transformed into drowning unconformities during subsequent phases of significant transgressions. These phases were associated with the installation of higher trophic levels, transforming or impeding carbonate production. The first drowning phase preceded the onset of the Selli episode, suggesting that rapid sea-level change and associated environmental change were already an important element of the early Aptian before the major phase of environmental change during the Selli episode. © 2014 Elsevier B.V.

Baudouin C.,rue Pierre Julien | Baudouin C.,Center dEtudes Mediterraneennes | Delanoy G.,University of Nice Sophia Antipolis | Delanoy G.,Center dEtudes Mediterraneennes | And 5 more authors.
Revue de Paleobiologie | Year: 2012

Ammonite faunas of the Sarasini Subzone (Upper Barremian) from the Baronnies (Drôme, France).- A rich ammonite fauna, taken in the Curnier region (Drôme, France) and dated from the Upper Barremian, Giraudi Zone, Sarasini Subzone, is described and studied here. Fifteen generic units, represented by more or less important samples, have been recognised : Phylloceras (Hypophylloceras), Phyllopachyceras, Protetragonites, Eulytoceras, Barremites, Melchiorites, Pseudohaploceras, Silesites, Macroscaphites, Audouliceras, ?Pseudocrioceras, Martelites, Heteroceras, Ptychoceras and Ptychohamulina. The genera showing a sufficiently significant sample have allowed to study the intraspecific variability of the species, especially the ones belonging to the genus Martelites. The sexual dimorphism between the taxas Macroscaphites yvani (Puzos) and Costidiscus recticostatus (d'Orbigny) is confirmed with an ontogenetic and biometric study. Ptychohamulina testeorum nov. sp., new specie of the Hamulinidae Gill family, is introduced.

Delanoy G.,Center dEtudes Mediterraneennes | Delanoy G.,University of Nice Sophia Antipolis | Baudouin C.,Center dEtudes Mediterraneennes | Boselli M.,57 bis avenue des Patriotes | Penage E.,Center dEtudes Mediterraneennes
Carnets de Geologie | Year: 2016

New investigations in the Vocontian Lower Aptian deposits resulted in the discovery of very rare specimens of heteromorphic ammonites whose specific morphological and ornamental features have led to the erection of Ivaldiceras gen. nov. Represented by a very limited number of specimens this new genus consists of two species: I. baratteroi gen. & sp. nov. and I. divajeuensis gen. & sp. nov. The suprageneric position of the new genus is difficult to determine because of the poor preservation of its sutural elements and the incomplete state of the specimens. The genus is tentatively assigned to the Family Macroscaphitidae HYATT, 1900, pending the study of better preserved material. © 2016, Carnets de Geologie. All rights reserved.

Baudouin C.,rue Frederic Mistral | Baudouin C.,Center dEtudes Mediterraneennes | Delanoy G.,University of Nice Sophia Antipolis | Moreno-Bedmar J.A.,National Autonomous University of Mexico | And 6 more authors.
Carnets de Geologie | Year: 2016

In spite of recent interest, the various species belonging to the genera Heminautilus SPATH, 1927, and Josanautilus MARTÍNEZ & GRAUGES, 2006, have never been the object of a general revision. More than 160 specimens belonging to various species of these two genera were studied, with the aim of identifying the specific characteristics and the stratigraphical and paleogeographical distribution of the various species which compose them, as well as to propose a phylogeny for the group. This study con-firms the non-synonymy of H. saxbii (MORRIS, 1848) and H. lallierianus (ORBIGNY, 1841), establishes that H. tejeriensis MARTÍNEZ & GRAUGES, 2006, and H. verneuilli (VILANOVA, 1870) represent junior synonyms of H. saxbii (MORRIS) and suggests the creation of the species H.? japonicus sp. nov. The origin of the genus Heminautilus SPATH from Pseudocenoceras SPATH, 1927, proposed by TINTANT and the origin of Jo-sanautilus MARTÍNEZ & GRAUGES from Heminautilus SPATH are both confirmed. © 2016, Carnets de Geologie. All rights reserved.

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