The Kopet-Dogh basin formed after the Middle Triassic orogeny in northwestern Iran and south western Turkmenistan. Upper Cretaceous strata of Iran contain diverse nannofloras. The Neyzar Formation, conformably overlies the Abtalkh Formation. These deposits mainly consist of 40 m of calcareous shales bluish gray marls, and a sandy limestone layer. Most previous calcareous nannofossil studies have been carried out by Hadavi and colleagues (Hadavi & Khodadadi, 2002; Hadavi et al., 2004). The top of the Abtalkh Formation (on the Kalat-Mashhad road), and the lower part of the Neyzar Formation (at the type locality and at Chahchaheh village) are similar formations. In the present study we have collected 21 samples from the upper part of the Abtalkh Formation and lower part of the Neyzar Formation in the Do-Baradar section, east of Kopet-Dogh. As a result, 16 families, 23 genera and 52 species have been identified. Based on the first or last occurrences of the marker taxa Micula murus, Ceratolithoides kamptneri and Micula prinsii, an age of Late Maastrichtian, corresponding to CC25-CC26 (Sissingh, 1977), is proposed for this section.

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