Document Type : Original Research Paper
Authors
1 M.Sc., Research Institute for Earth Sciences, Geology Survey of Iran, Tehran; Geology Survey of Iran, Shiraz, Iran
2 M.Sc., Faculty of Sciences, Isfahan University, Isfahan, Iran
Abstract
The Permian deposits in the Sibestan section located at 65 km. northwest of Tehran and consist of 3 formal Formations. In order from lower to upper: 1- Dorud Fm. consisting of 205 meters of siliciclastic deposits of early Permian age and according to the lithostratigraphy facies is divided into 10 rock units. 2- Ruteh Fm. consisting of 178 m. of limestone of Late early Permian (Murghabian) age. It also according to the lithostratigraphy facies is divided into 5 rock units. 3- Nessen Fm. consisting of 54 m. of limestone, shale and sandstone of lower Julfian age. This Formation is also divided into 8 lithologic units. The Permian sedimentary deposits terminates by bauxite-laterite horizon of Julfian equivalent age. This sequence is covered disconformably by 28.10 m. of yellowish gray platy limestone of strata Lower Triassic Elika Fm.
According to the paleontological studies, three biozones of foraminifers in Ruteh and Nessen formations have been identified:
Ruteh Fm.:
1- (Schubertella giraudi-Codonofusiella distincta assemblage zone) of Bolorian?-Kubergandian age.
2- (Cribrigenerina sumatruna- Langella ocarina assemblage zone) of Murghabian age.
Nessen Fm.:
3- (Paraglobivalvulina mira-Ichtyolaria assemblage zone), of Median?- Julfian age.
In addition, 14 species and genus and one subspecies of conodonts have been identified and also 2 conodonts biozones have been recognized in this section which correspond to the international conodonts.
Ruteh Fm.:
1- Sweetognathus whitei biozone (Early Permian).
Elika Fm:
2- Hindeodus parvus-Isarcicella isarcica biozone (Early Triassic).
3- Pachycladina symmetrica-P. oblique assemblage zone (Early Triassic).
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