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Carbonates and Evaporites

, Volume 22, Issue 2, pp 135–148 | Cite as

Sedimentology, depositional environment and sequence stratigraphy of the Asmari Formation (Oligocene-Lower Miocene), Gachsaran Area; SW Iran

  • Mohsen RanjbaranEmail author
  • Farajollah Fayazi
  • Ihsan Al-Aasm
Article

Abstract

This study investigates the depositional environment and sequence stratigraphy of the Asmari Formation (Oligocene-Miocene) in Gachsaran Area. The formation is carbonate sequence, which is laid down in the southern side edge Neotethys Ocean (Zagros area). The Asmari Formation represents sedimentation on a carbonate ramp. Seven major microfacies and three subfacies are recognized which include: MF-1) planktonic foraminifer wackestone-packstone, MF-2) nummulitic-bioclastic-corallinacean wackestone-packstone, MF-3) bioclastic grainstone, MF-4) ooid-grainstone, MF-5) bioclastic-miliolid-borelisid, MF-6) miliolid-intraclast-bioclast and MF-7) carbonate mudstones (laminated mudstone, fossiliferous mudstone and algal mudstones).

This carbonate succession consists of four, thick shallowing-upward sequences. Based on shallowing and deepening trend of depositional facies and changes in the cycle stacking pattern four third-order depositional sequences were identified.

With the concern of 7 microfacies kinds, five carbonate sedimentary environments are represented. These environments from basin to land: outer slope to basin and slope sited in outer ramp; shoal and shelf lagoon located between middle ramp-internal ramp; and restricted lagoon and low intertidal too supratidal set up in the internal ramp. The formation indicates a large-scale trend of decreasing accommodation upward.

The lower Asmari layers was laid down on open-marine conditions and represented by a laterally equivalent shaley faices, assigned to that generally the Pabdeth formation and communicated prograding side edge to the upward gradient attitudes, while the center to the upper parts of the formation were deposited in lower energy settings with more frequent evidence of exposure and evaporitic conditions, reflecting ramp settings established behind the prograding margin. The top side of the sequence is obviously marked by an erosional surface, which is overlaid by thick tidal flats. The surface erosional shows intense staining and leaching out suggesting diagenetic alteration during the sub-aerial exposure.

With petrographic methods five kinds of dolomite are differentiated in this formation: 1- dolomicrite 2- dolomicrosparite 3- sucrosic dolomite 4-cloudy center dolomite and 5-saddle dolomite.

Keywords

Dolomite Mudstone Foraminifera Microfacies Dolomitization 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. ALA, M.A., 1982, Chronology of Trap Formation and Migration of Hydrocarbons in the Zagros Sector of Southwest Iran:American Association of Petroleum Geologists Bulletin, v. 66, p. 1535–1541.Google Scholar
  2. AL-AASSM, I.S., TAYLOR, B.E., and SOUTH, B., 1990, Stable isotope analysis of multiple carbonate samples using selective acid extraction:Chemical Geology (Isotope Geoscience Section), v. 80, p. 119–125.CrossRefGoogle Scholar
  3. ALAVI, M., 1994, Tectonics of the Zagros orogenic belt of Iran; new data and interpretations:Tectonophysics, v. 229, p. 211–238.CrossRefGoogle Scholar
  4. ALAVI, M., 2004, Regional stratigraphy of the Zagros fold-thrust belt of Iran and its proforeland evolution:American Journal of Science, v. 304, p. 1–20.CrossRefGoogle Scholar
  5. AQRAWI A.A.M., KERAMATI, M., EHRENBERG, S.N., PICKARD, N., OALLEMI, A., SVANA, T., DARKE, G., DICKSON, J.A.D., and OXTOBY, N.H., 2006, The origin of dolomite in the Asmari Formation Oligocene-Lower Miocene, Dezful Embayment, SW Iran:Journal of Petroleum Geology, v. 29, no. 4, p. 381–402.CrossRefGoogle Scholar
  6. BERBERIAN, M., 1995, Master “blind” thrust faults hidden under the Zagros folds: Active tectonics and surface morphotectonics:Tectonophysics, v. 241, p. 193–224.CrossRefGoogle Scholar
  7. BERBERIAN, M., and KING, G.C.P., 1981, Towards a paleogeography and tectonic evolution of Iran:Canadian Journal of Earth Sciences, v. 18, p. 210–265.CrossRefGoogle Scholar
  8. BORDENAVE, M.L. and BURWOOD, R., 1990, Source rock distribution and maturation in the Zagros orogenic belt: provenance of the Asmari and Bangestan reservoir oil accumulations:Organic Geochemistry, v. 16, p. 369–387.CrossRefGoogle Scholar
  9. CAROZZI, A.V., 1989, Carbonate rock depositional models. Prentice Hall, Englewood Cliffs, N.J., 604 p.Google Scholar
  10. COSOVIC, V., DROBENE, K., and MORE, A., 2004 Paleoenvironmental model for Eocene foraminiferal limestones of Adriatic carbonate platform (Istrian Peninsula):Facies, v. 50, p. 61–75.CrossRefGoogle Scholar
  11. DUNHAM, R.J., 1962, Classification of carbonate rocks according to their depositional texture. In: Classification of Carbonate Rocks:American Association of Petroleum Geologists Bulletin, v. 1, p. 108–121.Google Scholar
  12. EMBRY, A.F. and KLOVAN, J.E., 1971, A Late Devonian reef tract on northeastern Banks Island, N.W.T.:Bulletin of Canadian Petroleum Geology, v. 19, p. 730–781.Google Scholar
  13. EVERS, H.J., 1977, Behbahan Geological map scale 1∶250000. Tehran: National Iranian Oil Company.Google Scholar
  14. FAKHARI, M. and MCQUILLAN, H., 1993, Bushehr Geological map scale 1∶250000. Tehran: National Iranian Oil Company.Google Scholar
  15. FLÜGEL, E., 2004, Microfacies Analysis of Limestone. Springer-Verlag, New York, 976 p.Google Scholar
  16. FRIEDMAN, G.M., 1959, Identification of carbonate minerals by staining methods:Journal of Sedimentary Petrology, v. 29, p. 87–97.Google Scholar
  17. HESSAMI, K., KOYI, H.A., and TALBOT, C.J., 2001a, The significance of strike-slip faulting in the basement of the Zagros fold and thrust belt:Journal of Petroleum Geology, v. 24, no. 1, p. 5–28.CrossRefGoogle Scholar
  18. HESSAMI, K., KOYI, H.A., TALBOT, C.J., TABASI, H., and SHABANIAN, E., 2001b, Progressive unconformities within an evolving foreland fold-thrust belt, Zagros Mountain:Journal Geological Society of London, v. 158, p. 969–981.CrossRefGoogle Scholar
  19. JAMES, G.A. and WYND, J.G., 1965, Stratigraphic nomenclature of Iranian oil consortium agreement area:Association of Petroleum Geologists Bulletin, v. 49, p. 2182–2245.Google Scholar
  20. JONES, B. and DESROCHERS, A., 1992, Shallow Platform Carbonates.In R.G. Walker and N.P. James, eds., Facies Models, Response to Sea Level Change. Geological Association of Canada, St. Johns Newfoundland, p. 277–302.Google Scholar
  21. KOOP, W.J. and STONELEY, R., 1982, Subsidence history of the Middle East Zagros basin, Permian to recent.In P.E. Kent, M.P. Bott, D.P. McKenzie, and C.A. William, eds., Philosophical Transactions Royal Society London, no. 305, p. 149–168.Google Scholar
  22. MOTIEI, H., 1993, Geology of Iran: Stratigraphy of Zagros in Treatise of Geology of Iran:Iran Geological Survey, no. 1, p. 281–289.Google Scholar
  23. PEDLEY, M., 1996, Miocene reef facies of Pelagian region (Central Mediterranean region).In E.K. Franseen, M. Esteben, W.C. Ward, and J.M. Rouchy, eds., Models for carbonate stratigraphy from Miocene Reef complexes of Mediterranean Regions: SEPM Concepts in Sedimentary Paleontology, no. 5, p. 247–259.Google Scholar
  24. POMAR, L., 2001, Types of carbonate platforms: a genetic approach:Basin Research, v. 13, p. 313–334.CrossRefGoogle Scholar
  25. READ, J.F., 1982, Carbonate margins of passive (extensional) continental margins: types, characteristics and evolution:Tectonophysics, v. 81, p. 195–212.CrossRefGoogle Scholar
  26. READ, J.F., 1985, Carbonate platform facies models:American Association of Petroleum Geologists Bulletin, v. 69, p. 1–21.Google Scholar
  27. TUCKER, M.E., 1985, Shallow marine carbonate facies and facies models.In P.J. Brenchley and B.P.J. Williams, eds., Sedimentology, recent development and applied aspects. Geological Society of London, Special Publications, v. 18, p. 139–161.Google Scholar
  28. TUCKER, M.E. and WRIGHT, V.P., 1990, Carbonate sedimentology. Blackwell Science Publishers, Oxford, 482 p.CrossRefGoogle Scholar
  29. VAN WAGONER, J.C., MITCHUM, R.M., CAMPION, K.M., and RAHMANIAN, V.D., 1990, Siliciclastic sequence stratigraphy in well logs, cores and outcrops: Tulsa, Oklahoma: American Association of Petroleum Geologists Methods in Exploration Series, no. 7, 55 p.Google Scholar
  30. VAN WAGONER, J.C., POSAMENTIER, H.W., MITCHUM, R.M., VAIL, P.R. SARG, J.F., LOUTIT, T.S., and HARDENBOL, J., 1988, An overview of the fundamentals of sequence stratigraphy and key definitions.In C.K. Wilgus, B.S. Hastings, C.G.St.C. Kendall, H.W. Posamentier, C.A. Ross, and J.C. Van Wagoner, eds., Sea level changes, an integrated approach. Society of Economic Paleontologists and Mineralogists Special Publication, no. 42, p. 39–45.Google Scholar
  31. VAZIRRI-MOGHADAM, H., KIMIA, GARI M., and TAHERI, A., 2006, Depositional environment and sequence stratigraphy of the Oligo-Miocene Asmari Formation in SW Iran:Facies, v. 52, p. 41–51.CrossRefGoogle Scholar
  32. WILSON, J.L., 1975, Carbonate Facies in Geologic History. Springer-Verlag, Berlin, 471 p.CrossRefGoogle Scholar

Copyright information

© Springer 2007

Authors and Affiliations

  • Mohsen Ranjbaran
    • 1
    Email author
  • Farajollah Fayazi
    • 1
  • Ihsan Al-Aasm
    • 2
  1. 1.Department of GeologyTarbiat Moallem UniversityTehranIran
  2. 2.Department of Earth SciencesUniversity of WindsorWindsorCanada

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