Document Type : Original Research Paper

Author

Associate Profesor, Department of Geology, Faculty of Science, Lorestan University, Lorestan, Iran

Abstract

Sedimentary setting and paleoecology of the rudist-bearing Upper Cretaceous  strata were studied in three sections in Khorram abad. The sections include: Tang Shabi Khone, Cham Sangar (Tarbur Formation) and Pir Shams Eldin (upper part of Amiran Formation). The Tang- E Shabi Khone and Chamsangar sections are located in Zagros Trust zone while, the Pir Shams Eldin  in Lorestan zone. On the basis of the recognized fossils, the three sections are assigned to the Late Cretaceous (Middle to Late Masstrichtian) and are comparable to Omphalocyclus- Loftusia Assemblage Zone. The petrography study showed that the three sections contain nine microfacies that deposited in an open marine, shoal and restricted marine that based on rudist sedimentary models, are comparable to the Inner- shelf basin prograding margin complexes (Tarbur Formation) and the low- angel open shelf margin complexes (Amiran Formation). Probably, Sepid Kuh Fault was detaching the these settings. Augmentation of entering the detrital and silica due to river injection and runoff and consequently to the eurotrophic conditions in the Tnage Shabi Khone and Pir Shams Eldin, frequency of agglutinate foraminifera were increased but in the chamsangar section  due to oligotraphy condition , frequency of hyaline foraminifera is increased. Distribution of the foraminifera and algae indicated that the Tarbur Formation is deposited in a photic zone though, some parts of the carbonates of the Amiran Formation were deposited in a aphotic zone.

Keywords

References
Alavi, M., 2004-.Regional statigraphy of the Zagros fold-Thrust belt of Iran and its proforland evolution, American Journal of science,304. p.1-20.
Cetari, R. and Satorio, D., 1995- Rudist and Facies of the Priadriatic domain, Agip, 207p.
Corda, L. and Brandano, M., 2003- Aphotic zone carbonate production on a Miocene ramp, central Apennines, Italy. Sediment Geol 161(1-2), p. 55-70.
Defrance, I. L. M., 1816-27- Dictionaire des Set Nat., 21, Paris.
Douvill, H., 1904- Etudes Géologiques. Partie 4, Paléontologie, Mollusques fossiles. In: MORGAN, J.DE (ed), Mission scientifique en Perse, Paris 3, p. 191–380.
Douville H., 1910- Etudes sur les rudistes. Rudistes de Sicile, d’ Algerie, d’Egypte, du Liban et de la Perse: Memoires de la Societe Geologique deFrance 41, p. 1-83.
Farinacci, A. and KöylÜoglu, M., 1985- Anatalyna korayi n. sp. in the phletic lineage of the Nezzazazzzatidae(Foraminifera) , Rev. Micropal., 28(2) .103-108.
Flugel, E., 2010- Microfacies of Carbonate Rocks, Analysis, Interpretation and Application, Springer, Berlin – Heidelberg, New York, 976 p.
Francis, J. E. and Frakes, L. A., 1993- Rudist Formation of the Cretaceous : A Paleo Ecological, Sedimentological and Stratig Raphical review. In V.P.Wright(ed), Sedimentology review.No,1: Black Well Scientific Publication, Oxford, p. 17-30.
Geel, T., 2000- Recognition of stratigraphic sequences in carbonate platform and slope deposits: empirical models based on microfacies analysis of paleogene deposits in southeastern Spain: Paleogeography, Paleoclimatology, Paleoecology, 155, p. 211- 238.
Hallock, P., 1985- Why are larger foraminifera large? Paleobiology, pp. 195- 208.
Hottinger, L., 1997- Shallow benthic foraminifera assemblages as signals for depth of their deposition and their limitation, Bull. Soc. Geol. France, 168, p. 491-505.
James, G. A.  and Wynd, J. G., 1965- Stratigraphic Nomenclature of Iranian Oil Consortium Agreement Area, American Association Petroleum Geologists Bull., 49(12), p. 2182–2245
Khazaei, A. R. Skelton, P. W. and Yazdi, M., 2010- Maastrichtian Rudist fauna from Tarbur formation (Zagros region-SW Iran), Preliminary. observations: Turkish Journal of Earth Sciences, v.19, p.703-719.
Lamarck, J. B., 1816- Suite des memoires sur les Fossiles des Enivrons de Paris. Annales de la Musée d’Histoire Naturelle de Paris, 5: 179-188.
Liewellyn,V. P., G., 1974- Geological map of Ilam-  Kuh Dast, 1:250 000.
Meric, E and Gormuz, M., 2001- the genus Loftusia, micropaleontology, p.47-37.
Meric, E and Mojab, h., 1977- Word wide geography distribution of the species of the foraminifera  genus Loftusia, istanbul university, fen fafultesi mecmvasi, B, 421 p.
Murray, J. W., 1991- Ecology and distribution of benthic foraminifera, In: Lee, J.J., Anderson, O.R. (Eds), Biology of Foraminifera. Academic Press, New York, p. 221–224.
NIOC (National Iranian Oil Company), 1976- Tang-E- Haft geological map, scale 1:100000.
NIOC (National Iranian Oil Company), 1977- Alshtar geological map, scale 1:100000.
Perin, C. and Bosellini, R., 2012- Paleobiogeography of scleractinian reef corals: Changing patterns during the Oligocene–Miocene climatic transition in the Mediterranean, Earth-Science Reviews 111, (1–2), PP. 1–24
Pomar, L., 2001- Types of carbonate platforms: a genetic approach. Basin Res 13, p. 313–334.
Reiss, Z. and Hottinger, L., 1984- The Gulf of Aqaba: Ecological Micropaleontology. Ecological Studies, Springer-Verlag, Berlin, Vol. 50, p. 1–354.
Ross, D. I. and Skelton, P. W., 1993- Rudist Formation of the Cretaceous: A Paleo Ecological, Sedimentological and Stratig Raphical review. In V.P.Wright(ed), Sedimentology review.No, 1: Black Well Scientific Publication, Oxford, p. 73-91.
Scott, R. W., 1990- Models and stratigraphy of mid Cretaceous reef communities. Gulf of Mexico, Soc. Ecom. Paleon. Miner. Conc. Sedim. Paleont. 2, 102 pp.
Sherkaty, S. and Letouzey, J., 2004- Variation of structural style and basin evolution in the Central Zagros (Izeh zone and Dezful beltl Iran): Marine and petroleum geology, 21(5), p. 35-554.
Stocklin, J., 1968- Structural history and tectonics of Iran: a review, American Association Petroleum Geologist Bulletin, 52, p.1229–1258.
Tucker, M. E. and Wright, V. P., 1990- Carbonate sedimentology, Oxford  Blackwell Scientific Publications, 425 pp.
Van Buchem, F., Gaumet, F., Vedrenne, V. and Vincent, B., 2004- Middle East sequence stratigraphy, Part 1: SW Iran, N. I. O. C. and I.F.P. report.
Warren, W. J., 2000- Dolomite: Occurrence, evolution and economically important association, Earth Sciences Review, 52, pp. 1-181.
Wynd, J. G., 1965- Biofacies of the Iranian oil Agreement area, N .I .O. C. report, No 1089