An account of the bio- and magnetostratigraphy of the Upper Tithonian—Lower Berriasian interval at Le Chouet, Drôme (SE France)

Abstract

This paper discusses the results of a study of the Le Chouet section, its lithologies, facies, magnetic properties and fossil record (ammonites, calcareous nannofossils, calpionellids and calcareous dinoflagellates). Data obtained have been applied to give a precise biostratigraphy for this carbonate sequence as well as a paleoenvironmental reconstruction. Its relationship to magnetostratigraphy, based on a modern study of a French site, is important. Investigation of the micro-and macrofossils shows that the site comprises a sedimentary sequence in the Microcanthum to Jacobi ammonite Zones, and the Chitinoidella, Crassicollaria and Calpionella Zones. Several calpionellid and nannofossil bioevents have been recorded on the basis of the distribution of stratigraphically important planktonic organisms. The site allows us to calibrate the levels of various biomarkers and biozonal boundaries, and correlate them with the magnetozones M20n, M19r and M19n.

Upper Tithonian Himalayitidae Spath, 1925 (Perisphinctoidea, Ammonitina) from Le Chouet (Drôme, France): implications for the systematics

“…Thus, there is no counter-argument to consider an expansion of the C. intermedia Subzone in the Sidi Khalif Formation. This hypothesis is more consistent with the calpionellids data at Le Chouet (Wimbledon et al 2013;Bulot et al 2014).…”

“…P. andreaei is reported from South East Spain and France, Italy, Bulgaria, Tunisia and Morocco. Since D. vulgaris Tavera non Burckhardt is herein considered as a microconch of P. andreaei, the D. vulgaris Zone of Sarti (1988) is a junior subjective synonym of the P. andreaei Zone introduced by Wimbledon et al (2013). (Tavera, 1985) Fig.…”

“…A first account of the most significant late Tithonian Perisphinctoidea (Ammonitina) from Le Chouet (Drôme, France) highlighted several taxonomic and biostratigraphic problems (Bulot et al 2014). Regarding the family Himalayitidae Spath, 1925, the genus Micracanthoceras Spath, 1925 was discussed and the new genera Ardesciella and Pratumidiscus were introduced for Mediterranean himalayitids that had previously been attributed to Corongoceras Spath, 1925 or Riasanites Spath, 1923. A new biostratigraphic scheme was proposed for the upper Tithonian of Le Chouet (Wimbledon et al 2013;Bulot et al 2014). A Moravisphinctes fischeri Subzone was introduced for the upper part of the Micracanthoceras microcanthum Zone that correlates with the uppermost part of the calpionellid Tintinopsella remanei and Crassicolaria intermedia Subzones (Crassicollaria Zone).…”

“…1. Locality map of Le Chouet (Les Près, Drôme, SE France), integrated stratigraphy and distribution of the late Tithonian Himalayitidae studied in this paper (modified after Wimbledon et al (2013) Burckhardt, 1912, by subsequent designation of Cantú-Chapa (1968, p. 22).…”

A review of magnetostratigraphic results from the Tithonian–Berriasian of Nordvik (Siberia) and possible biostratigraphic constraints

“…More study has revealed that the bases of the Alpina and Jacobi biozones are not coincident (as has often been stated in the past), and neither of them is seen to lie close to the base of M18r (e.g. Wimbledon et al 2013): in addition, study has revealed problems with definition/demarcation of the Jacobi Subzone. Examining ammonites and calpionellids, some cited by Ogg & Lowrie (1986), and nannofossils, the particular focus has therefore shifted to levels where there are more closely spaced biotic markers, that is, within and at the base of M19n.2n.…”