Biostratigraphy and palaeoecology of the Asmari Formation at southwest of Firozabad

Document Type : مقالات پژوهشی

Authors

• Behnaz Kalanat
• Hossein Vaziri Moghaddam
• Azizollah Taheri

10.22067/sed.facies.v3i1.2717

Abstract

Three assemblage zones (Rupelian-Chattian age) have been identified by distribution of large benthic foraminifera in the study area. The Firozabad section was compared with Chahangir (Rupelian) and Dil (Chattian-Burdigalian) sections. Early Oligocene carbonate (Firozabad and Chahangir sections) was deposited at the edge of Zagros foreland basin whereas towards the center of the basin, the Pabdeh Formation continued to accumulate. The Miocene part of the Asmari Formation, as seen in the Dil section, is absent in Firozabad and Chahangir sections. This suggests that Oligocene sea level fall restricted marine deposition and Asmari Formation replaced laterally by the Gachsaran Formation. The biotic associations and palaeolatitudinal reconstructions suggest that carbonate sedimentation took place in tropical waters under oligotrophic conditions in the study area, a favorable environment for photozoan assemblages. The dominance of heterozoan assemblages seems to be related to the palaeoecology and evolution of zooaxanthellate corals, which were not able to construct reefs against the destructive waves; actually they lived in the meso-oligotrophic zone.

Keywords

• Oligocene
• heterozoan assemblages
• Biostratigraphy
• Asmari Formation
• large benthic foraminifers

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References

الله‌کرم پور دیل، م.، صیرفیان، ع.، وزیری مقدم، ح. و امیری بختیار، ح.، 1387. زیست چینه نگاری سازند آسماری در یال شمالی تاقدیس کوه دیل در شمال گچساران، دوازدهمین همایش انجمن زمین شناسی ایران، اهواز.

سعیدی اوتاکند، م.، آقانباتی، ع.، وزیری مقدم، ح. و پرتوآذر، ح.، 1387. زیست چینه نگاری نهشته های سازند آسماری در جنوب باختری ایران، دوازدهمین همایش انجمن زمین شناسی ایران، اهواز.

بختیاری، س.، 1384. اطلس راههای ایران با مقیاس 1:1000000. مؤسسه جغرافیایی و کارتوگرافی گیتاشناسی. 288ص.

Adams, T.D., and Bourgeois, F., 1967. Asmari Biostratigraphy: Geological and Exploration, IOOC Report, 1074, (unpublished).

Alavi, M., 2004. Regional stratigraphy of the Zagros fold-thrust belt of Iran and its proforeland evolution. American Journal of Science, 304: 1–20.

Amirshahkarami, M., Vaziri-Moghaddam, H., and Taheri, A., 2007a. Paleoenviornmental model and sequence stratigraphy of the Asmari Formation in Southwest Iran: Historical Biology, 19: 173-183.

Amirshahkarami, M., Vaziri-Moghaddam, H., and Taheri, A., 2007b. Sedimentary facies and sequence stratigraphy of the Asmari Formation at the Chaman-bolbol: Zagros Basin, Iran, Journal of Asian Erath Sciences, 29: 947-959.

Biavington-Peny, S.G., and Racey, A., 2004. Ecology of extant Nummulitids and other large Foraminifera: Aplication in paleoenvironmental analyses, Earth-Science Riviewers, 67: 219-265.

Brandano, M., and Corda, L., 2002. Nutrients, See level and tectonic: Constrain for the faciesarchitecture of Miocene carbonate ramp in central Italy, Blackwell science, 14(4): 257-262.

Brandano, M., Frezza, V., Tomassetti, L., and Cuffaro, M., 2009. Heterozoan carbonates in oligotrophic tropical waters: The attard member of the Lower coralline limestone Formation (Upper Oligocene, Malta), Palaeogeography, Palaeoclimatology, Palaeoecology, 272: 1-10.

Cosovic, V., Drobne, K., and Moro, A., 2004. Palaeoenvironmental model for Eocene foraminiferal limestone of the Adriatic carbonate platform, Facies, 50: 61-75.

Ehrenberg, S.N., Pickard, N. A.H., Laursen, G.V., Monibi, S., and Mossadegh, Z. K., 2007. Strontium isotope stratigraphy of the Asmari Formation (Oligocene-Lower Miocene), SW Iran, Journal of Petroleum Geology, 30: 102-128.

Flugel, E., 2004. Microfacies of carbonate rocks. Springer, Berlin, 976 p.

Geel, T, 2000. Recognition of stratigraphic sequence in carbonate platform and slope deposites, Palaeogeography, Palaeoclimatology, Palaeoecology, 155: 211- 238.

Hallock, P., Forward, L.B., and Hansen, J., 1986. Influence of environment on the test shape of Amphistegina, Journal of Foraminiferal Research, 16(3): 224-231.

Heydari, E., 2008. Tectonics versus eustatic control on supersequences of the Zagros Mountains of Iran, Tectonophysics, 451: 56–70.

Hottinger, L., 1997. Shallow benthic foraminifera assemblages as signals for depth of their deposition and their limitation, Bull. Soc. Geol. Fr, 4: 491-505.

James, N.P., 1997. The cool-water carbonate depositional realm. In: James N.P, Clarke, 21 J. (Eds), Cool-water Carbonates. Soc. Econ. Paleont. Mineral. Spec. Publ., 56: 1–20.

James, G.A., and Wynd, J.G., 1965. Stratigraphic nomenclature of Iranain Oil Consortium, agreement area, American Association of Petroleum Geologists Bullten, 49: 2118- 2245.

Kumar, A., and Saraswati, P.K., 1997. Response of larger foraminifera environments: An example fpr the Oligocene-Miocene sequence of Kutch, India, Palaeogeography, Palaeoclimatology, Palaeoecology, 136: 53-65.

Lee, J.J., 1990. Fine structure of rodophycean profyridium purpureum insitu in Peneroplis pertusus and P. asicularis, J. Foramin. Res., 20: 162-169.

Lees, G.M., 1993. Reservoir rocks of persian oil Welds, AAPG Bulletin, 17: 224–240.

Laursen, G.V, Monibi, S., Allan, T.L., Pickard, N.A.H., Hosseiney, A., Vincent, B., Hamon, Y., Van Buchem, F.S.H., Moallemi, A., and Driullion, G., 2009. The Asmari Formation revisited: Changed stratigraphic allocation and new biozonation, First international petroleum conference & exhibition, Shiraz, Iran.

Mc Gowran, B., and Li, Q., 2000. Evolutionary palaeoecology of Cainozoic foraminifera: Thethys, Sout Australasia, Historical Biology, 15: 3-27.

Mossadegh, Z.K., Haig, D.W., Allan, T., Adabi, M.H., and Sadeghi, A., 2009. Salinity changes during Late Oligocene to Early Miocene Asmari formation deposition, Zagros mountains, Iran, Palaeogeography, Palaeoclimatology, Palaeoecology, 272: 17-36.

Mutti, M., and Hallok, P., 2003. Carbonate system along nutrient and temperature gradient: Some sedimentological and geochemical constraits, Earth-Science, 92: 465-475.

Pomar, L., Brandano, M., Westphal, H., 2004. Environmental factors influencing skeletal grain sediment association: A critical review of Miocene examples from western Mediterranean, Sedimentology, 51: 627-651.

Pomar, L., and Hallock, P., 2008. Carbonate factories: A conundrum in sedimentary Geology, Earth-Science Reviewers, 87: 134- 169.

Sadeghi, R., Vaziri-Moghadam, H., and Taheri, A., 2009. Biostratigraphy and palaeoecology of Oligo- Miocene succession in Fars and Khuzestan areas (Zagros Basin, SW Iran), Historical Biology, in press.

Seyrafian, A., 2000. Microfacies and depositional environment of Upper Asmari Formation at Dehdez area (a correlation across central Zagros Basin), Carbonates and Evaporates, 15(2): 121-129.

Seyrafian, A., and Hamedani, A., 1998. Microfacies and depositional environment of the Upper Asmari Formation (Burdigalian), North - Central Zagros basin, Iran, N. Jb. Geol. Paleont. Abh, 210(2): 129-141.

Thomas, A.N., 1948. The Asmari limestone of southwest Iran, ALOC Report 706. Unpublished.

Toler, S.K., and Hallock, P., 1998. Shell malformation in stressed Amphistegina population, relation to biomineralization and palaeoenvironmental potential, Marine Micropalaeontology, 34: 107-115.

Vaziri - Moghaddam, H., Kimiagari, M., and Taheri, A., 2006. Depositional environment and sequence stratigraphy of the Oligocene - Miocene Asmari Formation in SW Iran, Springer-Verlage, 52: 41-51.

Wilson, M.E.J., and Vecsei, A., 2005. The apparent paradox of abundant foramol facies in low latitudes, their invironmental significance and effect on platform development, Earth Sci. Rev, 69: 133-168.