Document Type : Original Research Paper


1 1Department of Geology, Faculty of Earth Sciences, University of Shahid Beheshti, Tehran, Iran.

2 Department of Geology, Faculty of Earth Sciences, University of Shahid Beheshti, Tehran, Iran.


The Early Cambrian Lalun Formation in Poshte- Badam block has been studied in Bahmoo section with 550 m thickness, to illuminate its sedimentary environment and sea level changes. The field investigations, collection of 110 paleocurrent data, petrography, study of SEM images and XRD analysis of shale samples have been used for facies analysis, paleocurrent recognition and sedimentary environment reconstruction. The facies analyses imply 5 silisiclastic coarse grained (Gm), medium grained (Sp, St, Sh) and fine grained (Fl) lithofacies and 1 carbonate (dolomite) microfacies. The lithofacies, bipolar bimodal paleocurrent pattern and petrographic evidences such as the existence of glauconitic sandstones with high textural and compositional maturity imply deposition of these sediments in a Tidal Flat environment. Studying the relative sea level changes of Lalun deposits in this area imply two sequences which have been bounded between SB1 unconformities.


Assereto, R., 1963- The Paleozoic formations in central Alborz Iran. Riv. Ital., Paleontology, 6, 503-543.
Catuneanu, O., 2006- Principles of sequence stratigraphy. Elsevier, 375 p.
Chamley, H., 1989- Clay sedimentology: Springer Verlag Berlin, Heidelberg, 623 p.
Coe, A.  L., (Ed.) 2003- The Sedimentary record of sea-level change. CambridgeUniversity Press., 288 p.
Cotton, F. A., Wilkinson, G., Murillo, C.A., Bochmann, M., 2003- Advanced inorganic chemistry. New York., 1355 p.
Dickson, J. A. D., 1965- A modified staining technique for carbonates in thin section: Nature., v. 205, p. 587.
Einsele, G.,2000- Sedimentary Basin: Evolution, Facies and Sediment Budget (2th ed), Springer Verlag, 292 p.
Folk, R. L., 1980- Petrology of sedimentary rocks. Hemphill, Austin, Texas, 159 p.
Grassman, R. B., Milet, J. C., 1961- Carbonate removal from soils by a modification of the acetate buffer method: Journal of Soil., 25, 325-326.
Haq, B. U., 1991- Sequence stratigraphy, sea-level change and significance for the deep sea. In Sedimentation, Tectonics and Eustasy (D. I. M. Mac Donald, Ed.), pp. 3-39.  International Association of Sedimentologists Special Publication 12.
Hardy, R.  and Tucker, M. E., 1988-  X-ray powder diffraction of sediments. In Tucker, M. E.,  eds., Techniques sedimentology. Blackwell, London. 349 p.
Harms, J. C., Southard, J. B., Walker, R. G., 1982- Structures and Sequence in Clastic Rock. SEPM, Short Course., 1, 55.
Johnson, H. D. and Baldwin, C. T., 1996- Shallow clastic seas, in Reading, H. G., eds., Sedimentary Environment. Third ed., Blackwell, Oxford, 232-281.
Kolodny, Y., Chaussidon, M., Katz, A., 2005- Geochemistry of a chert breccia, Geochemica et Cosmochimica Acta., 69, 427-439.
Kunze, C. W., 1965- Pretreatment for mineralogical analysis, in: Method of soil analysis, Black C. A et al. Amer. Soc. of Agronomy mc. 651-675.
Lobo, C. P. Osbrone, R. H., 1976- Petrology of the Late Precambrin- Cambrian sandstons in the eastern Mojave Desert southeastern California. Journal Sed. Petrol., 46, 829- 846.
Mehra, O. P., Jackson, M. L., 1960- Iron oxid removal from soils and clay by a dithionitic–citrate system buffered with bicarbonate. Journal of Clays and Clay Mineral., 7, p. 313-325.
Meunier, A., 2005- Clay: Springer Verlag BerlinHeidelberg, 427 p.
Miall, A. D., 1996- The Geology of Fluvial deposits: Sedimentary Facies, Basin Analysis and Petroleum Geology. Springer-Verlag, New York, 582p. 
Miall, A. D., 1997- The Geology of stratigraphic sequences. Springer Verlag, 443p.
Miall, A. D., 2000- Principles of sedimentary basin analysis. Springer Verlag, 616 p.
Orton G. J. and Reading, H. G., 1993- Variability of deltaic processes in terms of sediment supply, with particular emphasis on grain size. Sedimentology., 40, 475-512.
Pettijohn, F. J., 1975- Sedimentary Rocks. Harper and Row. New York., 628 p.
Potter, P. E., Pettijohn, F. J., 1975- Paleocurrents and basin analysis: 2th ed., Springer- Verlag, 425 p.
Reading, H. G. and Collinson, J. D., 1996- Clastic coasts , in Reading, H. G., eds., Sedimentary Environment. Third ed., Blackwell, Oxford, 154-232.
Reinson, G. E., 1984- Barrier island and associated strand- plain systems. In: R.G. Walker (ed.), Facies Models, 2nd ed., Geo Science Canada., 119-141.
Schmidt, K. Soffel, H., 1983- Mesozoic- Cenozoic geological event in central- east Iran and their relation to paleomagnetic result. Minestry of Mines and Metals Geological Survey of Iran., report no. 51, 27- 35.
Selley, R. C., 1996- Ancient sedimentary environments. 4th ed., Champman & Hall, London, 300 p.
Sibley, D. F.,  Gregg, J. M., 1987- Classification of dolomite rock texture: Journal of  Sedimentary Petrology., 57, 967-97.
Tucker, M. E., 1993- Sedimentary rocks in the field. Wiley Pub, 2th ed. 153 p.
Tucker, M. E., 2001- Sedimentary petrology: an introduction to the origion of sedimentary rocks: Blackwell, Scientific Publication, London, 260 p.
Weaver, C. E., 1989- Clays, muds, and shales: Development in Sedimentology, Elsevier, Scientific Publication, 819 p.