Document Type : Original Research Paper


1 Department of Geology, University of Isfahan. Iran

2 Institut für Geowissenschaften der Christian-Albrechts-Universität zu Kiel, German

3 Department of Geology, University of Isfahan. Iran Institut für Geowissenschaften der Christian-Albrechts-Universität zu Kiel, German


     Two bryozoan species are described from the Geirud Formation (Upper Devonian) of Central Alborz. The Geirud Formation is a sequence of nearly 340 meters of alternating silisiclastics and limestone and 1-2 andesitic lava units, with extensive exposures in the Central Alborz mountains. The study comprises the Type Section of the Geirud Formation in the Geirud valley and two sections in Zaigun and Lalun valleys near the Type Section, all in northern Tehran (Fig.1).  In  some calcareous beds we  found bryozoan species from Famennian.  Trepostome Schulgina mutabilis Troizkaya, 1975 is known from the Upper Devonian (Famennian) of Central Kazakhstan. The Ascopora .sp. is the earliest known representative of habdomesine genus Ascopora Trautschold, 1876. This is the first study on the bryozoans of the Geirud Formation in Central Alborz.


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