Boletín del Instituto de Fisiografía y Geología, Volumen 83, 2003: 15-26.

ORIGINAL ARTICLE

Oxfordian belemnites and ammonites from Rostam Kola, Northern East Alborz, North Iran

Nino Mariotti, Robert Weis, Mostafa Falahatgar, Horacio Parent & Mojtaba Javidan

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N. Mariotti [nino.mariotti@uniroma1.it]: Dipartimento di Scienze della Terra, Università ‘La Sapienza’ P. le A. Moro 5, I-00185 Roma, Italy.

R. Weis [rweis@mnhn.lu]: Section Paléontologie, Musée national d’histoire naturelle, 25 rue Münster, L-2160 Luxembourg, Grand-duchy of Luxembourg.

M. Falahatgar [mostafa.mo2@gmail.com]: Department of Geology, Shahrood Branch, Islamic Azad University, Shahrood, Iran.

H. Parent [parent@fceia.unr.edu.ar]: Laboratorio de Paleontología, IFG, FCEIA, Universidad Nacional de Rosario, Pellegrini 250, 2000 Rosario, Argentina.

M. Javidan: Department of Geology, Shahrood Branch, Islamic Azad University, Shahrood, Iran.

Abstract

A Middle Oxfordian Jurassic belemnite fauna, associated with ammonites, from the Lar Formation at Rostam Kola (North Iran) is described for the first time. The specimens have been assigned to the following taxa: Hibolithes hastatus, Hibolithes aff. beyrichi, Pachybelemnopsis latesulcatus, Duvalia didayana, Duvalia monsalvensis, Rhopaloteuthis cf. argoviana and Rhopaloteuthis sauvanausa. Ammonites collected from the same belemnite bearing levels allow to refer the belemnite fauna to the Middle Oxfordian Transversarium Zone. Only a few Tethyan belemnite assemblages are recorded in the Middle Oxfordian, but it is possible to establish a close affinity with the taxa of the Mediterranean Province. The ammonites associated with the belemnites as also the ammonites from the upper levels of the section show clear Submediterranean affinities. All the ammonites known from previous and present surveys in the study area belong to the families Perisphinctidae and Ataxioceratidae. The species in new samples are Perisphinctes cf. parandieri, Perisphinctes (Subdiscosphinctes) sp. A, Orthosphinctes sp. A, Orthosphinctes sp. B, Lithacosphinctes? sp. A and Passendorferia cf. gygii.

Key-words: Belemnites, Ammonites, Lar Formation, Oxfordian, East Alborz, Iran.