Circulichnis and other trace fossils from Member 5 of Mila Formation in Tuyeh-Darvar section, Eastern Alborz Mountain, north Iran

Mila Formation includes five members in the Tuyeh-Darvar section, west Damghan. Fifth Member of formation comprises alternations of calcareous shale, limestone and green shales. Trace fossils of this member includes Cruziana problematica, Gordia isp., Helminthopsis abeli, Helminthopsis tenuis, Palaeophycus striatus, Planolites beverleyensis, Psammichnites gigas, Scolicia strozzii and Treptichnus pedum. Circulichnis montanus abundant in the upper most layers of the fifth Member and is circular cylindrical ring in shape. Circulichnis is a fodinichnion, that produced by progressive and plasticity behaviors of annelids. It seems that these trace fossils are belong to the mid parts of the turbidite rhythmic sequences and formed in the turbidity conditions of the sedimentary environment.