Remarks on the Tithonian–Berriasian ammonite biostratigraphy of west central Argentina

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Remarks on the Tithonian–Berriasian ammonite biostratigraphy of west central Argentina

Journal Title: Volumina Jurassica - Year 2015, Vol 13, Issue 2

Abstract

Status and correlation of Andean ammonite biozones are reviewed. Available calpionellid, nannofossil, and radiolarian data, as well as radioisotopic ages, are also considered, especially when directly related to ammonite zones. There is no attempt to deal with the definition of the Jurassic–Cretaceous limit. Correlation of the [i]V. mendozanum[/i] Zone with the [i]Semiforme [/i]Zone is ratified, but it is open to question if its lower part should be correlated with the upper part of the [i]Darwini [/i]Zone. The [i]Pseudolissoceras [/i][i]zitteli[/i] Zone is characterized by an assemblage also recorded from Mexico, Cuba and the Betic Ranges of Spain, indicative of the [i]Semiforme[/i]–[i]Fallauxi [/i]standard zones. The[i] Aulacosphinctes proximus[/i] Zone, which is correlated with the Ponti Standard Zone, appears to be closely related to the overlying [i]Windhauseniceras internispinosum[/i] Zone, although its biostratigraphic status needs to be reconsidered. On the basis of ammonites, radiolarians and calpionellids the [i]Windhauseniceras internispinosum[/i] Assemblage Zone is approximately equivalent to the [i]Suarites bituberculatum[/i] Zone of Mexico, the [i]Paralytohoplites caribbeanus[/i] Zone of Cuba and the [i]Simplisphinctes[/i]/[i]Microcanthum [/i]Zone of the Standard Zonation. The [i]C. alternans[/i] Zone could be correlated with the uppermost [i]Microcanthum [/i]and “[i]Durangites[/i]” zones, although in west central Argentina it could be mostly restricted to levels equivalent to the “[i]Durangites [/i]Zone”. The [i]Substeueroceras koeneni[/i] Zone ranges into the [i]Occitanica [/i]Zone, [i]Subalpina [/i]and [i]Privasensis [/i]subzones, the[i] A. noduliferum[/i] Zone could be equivalent to the [i]Dalmasi[/i] Subzone, [i]Occitanica [/i]Zone, to lower part of the [i]Boissieri [/i]Zone, and the [i]S. damesi [/i]Zone could range through the upper part of the [i]Boissieri [/i]Zone to the lower part of the [i]Pertransiens [/i]Zone. Division of the [i]Substeueroceras koeneni[/i] Zone and a precise correlation between the Andean ammonite zones and the international standard require new systematic and stratigraphic studies.

Authors and Affiliations

Alberto RICCARDI

Keywords

Tithonian–Berriasian ammonites west central Argentina calpionellids nannofossils radiolarians geochronology

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EP ID EP81386
DOI 10.5604/17313708/1185692
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