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Nasrollah Abbassi

Famarini Bozchalouei, N.,  Abbassi , N., Salsani, A., Zohdi, A.
Neoprotrozoic-Cambrian boundary in Soltanieh Formation by the ichnological studies, Seyedkandi section, Soltanieh Mountains, NW Iran
مرز نئوپروتروزوییک-کامبرین در سازند سلطانیه بر مبنای مطالعات ایکنولوژی، برش سیدکندی، کوههای سلطانیه، شمال باختری ایران
Abstract


Soltanieh Formation comprises seven informal submembers as alternation of dolomites and shales, more than 1110 meters in thickness, was surveyed in the Seyedkandi section, 32 km southwest of Zanjan, northwest Iran. These submembers were subdivided as lower dolomite, lower shale, second dolomite, second shale, third dolomite, upper shale and upper dolomite, respectively. Based on ichnological data from 109 specimens, 23 ichnogenera and 42 ichnospecies have been recognised, as following as: Archaeonassa fossulata, Archaeonassa isp., Cruziana problematica, Cruziana semiplicata, Cruziana isp., Diplichnites gouldi, Diplichnites isp., Gordia marina, Helmintoidea isp., Helminthopsis isp., Hormosiroidea isp., Isopodichnus isp., Monocraterion isp., Monomorphichnus isp., Neonereitesuniserialis, Neonereites biserialis, Neonereites isp., Nereites imbricate, Nereites isp.1, Nereites isp.2, Palaeobullia isp, Palaeophycus cf. annulatus, Palaeophycus heberti, Palaeophycus striatus, Palaeophycus isp., Planolites beverleyensis, Planolites montanus, Planolites isp., Phycodes palmatum, Rusophycus isp., Scolicia prisca, Scolicia isp.1, Scolicia isp.2, Skolithos isp., Subphyllochorda isp., Taenidium isp., Taphrhelminthopsis recta, Taphrhelminthopsis isp., Treptichnus bifurcus, Treptichnus pedum, Treptichnus pollardi, Treptichnus isp. The abundance of trace fossils is very high in the second shale submember, so that 99 specimens were collected from this rock unit. Ichnofossil data from the studied section showsthat the Neoproterozoic-Cambrian boundary is located in the 8 m above the base of second dolomite submember in the studied section, where the first occurrence of Treptichnus pedum was been recorded.

 

 

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