Scientific Quarterly Journal of Geosciences

Scientific Quarterly Journal of Geosciences

Microfacies and depositional environment of the Qom Formation in the Semnan area

Authors
Sadat Feiznia 1
Hamidreza Mosaffa 2
1 Faculty of Natural Resources, Tehran University , Tehran, Iran
2 Geological Survey and Mineral Exploration of Iran, Tehran, Iran
Abstract
The Qom Formation constitutes up to 136 meters of fossiliferous limestones with interbeds of gypsiferous marl in the south of Semnan. Its lower contact is paraconformity with red shales of the Lower Red Formation and its upper contact is also paraconfomity with red shales of the Upper Red Formation. The benthic Foraminifers indicate the Burdigalian age (equivalent to f member in central part of sedimentary basin) for the Qom Formation rocks in the studied area.
Field evidences and petrographic studies together with microfacies analysis, led to the recognition of four sub- environments including Open Marine, Barrier, Lagoon, and Tidal Flat. This environment is similar to the present-day carbonate environments such as the Persian Gulf, and Bahamas whose sediments were deposited in an epicontinental platform.
Keywords
Microfacies, Qom Formation, Semnan

Subjects

Carozzi, A.V., 1989 - Carbonate rock depositional models. A microfacies Approach. Prentice Hall, Newjersey, 604 P. 
Dunham, R.J.,1962- Classification of Carbonate Rocks According to Depositional Texture. Am. Ass. Pet. Geol. Mem. 1, PP. 108 -121.
Feiznia, S., 1983- Depositional and Diagenetic Environments of Carbonate- Siliciclastic Rocks of the Glen Dean Formation (Upper Miss), Illinois Basin, USA, Ph. D Thesis, University of Illinois, U.S.A, 210 P.
Flugel, E., 1982- Microfacies Analysis of limestones. Springer Verlag, Berlin, 633.P.
Tucker, M.E., 1991- Sedimentary Petrology, Blackwell, London
Wilson, J.L.,1975- Carbonate Facies in Geologic History. Springer Verlag, 471P.
Wray, J.,1977- Calcareous Algae. Elsevier Sci. Pub.,185 p.
Wright, V.P.,1992- A Revised Classification of Limestones, Sed Geol., No. 76, PP. 177-185.
Scientific Quarterly Journal of Geosciences
Volume 7, 27-28
Spring & Summer 1999, vol. 7, No. 27-28
Summer 1999
Pages 64-77