Reineckeiidae (Ammonoidae) Family of the Dalichai Formation in Damghan Area (East Alborz), Iran

摘要

The present study is concerning the systematic descriptions of the Middle Jurassic (Callovian) ammonite fauna from the Damghan Area (eastern Alborz) and contains a rather rich ammonite fauna. The described ammonites come from the Middle part of the Dalichai Formation, consisting of an alternation of green marl, grey limestone and marly limestone. In this research, the biostratigraphy of these rocks is discussed with special emphasis on the abundant ammonite fauna (Reineckeiidae family). Altogether, 74 specimens of ammonites belonging to 14 species, 3 genera, 3 sub genera from Reineckeiidae family are described. Palaeobiogeographically the ammonite fauna is closely related to that of the sub-Mediterranean Province of the northwestern Tethys. The ammonites represent four zones, i.e. Rehmannia (Loczyceras) cf. segestena (Anceps Zone), Rehmannia (Loczyceras) reissi (Anceps Zone), Rehmannia (Loczyceras) rehmanni (Anceps Zone), Rehmannia (Loczyceras) sequanica densicostata (Coronatum Zone), Reineckeia (Tyrannites) convexa (Gracilis Zone), Reineckeia (Tyrannites) pictava (Gracilis Zone), Reineckeia (Reineckeia) anceps anceps (Anceps Zone), Reineckeia (Reineckeia) anceps elmii (Anceps Zone), Reineckeia (Reineckeia) cf. fehlmani (Anceps Zone), Reineckeia (Reineckeia) nodosa (Athleta Zone), Collotia cf. multicostat (Anceps Zone), Collotia cf. gaillardi (Coronatum Zone), Collotia cf. oxyptychoides (Athleta Zone), Collotia cf. collotiformis (Athleta Zone).