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

RICCARDI, A. C.

Volumina Jurassica

Polish Geological Institute

Lugar: Warsaw; Año: 2015 vol. 13 p. 23 - 52

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