On the occurrence of Neoplanorbulinella Matsumaru, 1976 (Foraminifera) from the late Oligocene of Central Iran (Qom Formation): Palaeobiogeographic implications

Abstract

The shallow marine carbonates of the upper Oligocene Qom Formation yielded several occurrences of the foraminiferan genus Neoplanorbulinella Matsumaru. Neoplanorbulinella saipanensis Matsumaru has so far been recorded from the late Eocene–early Miocene of Japan and late Oligocene of NE Italy whereas N. malatyaensis Gedik is only reported from the Oligocene from its type locality in the Malatya Basin, eastern Turkey. The new records reported here from the Qom Formation indicate that both species occur in the Dobaradar section, ca. 10 km south of the city of Qom in North–Central Iran. The palaeogeographic distribution of these two species therefore has to be extended as far as the palaeolongitude of current Central Iran. The accompanying larger benthic foraminifers, including Miogypsinoides complanatus (Schlumberger), M. formosensis Yabe and Hanzawa, Spiroclypeus margaritatus (Schlumberger), Operculina complanata (Defrance), and Risananeiza pustulosa Boukhary et al., indicate the upper Chattian SBZ 23 Zone. The co-existence of the N. saipanensis and N. malatyaensis points to suitable palaeobiogeographic conditions of Central Iran to host Western and Eastern Tethyan taxa.