Lithology and Diagenetic Processes of the Baluti Formation (Upper Triassic) from the Amadyia Area, Kurdistan Region, North-Iraq

Waleed S. Shingaly
Geology department, Salahaddin University, Erbil, Iraq


Lithologic characteristics and diagenitic processes of the Baluti Formation (Upper
Triassic) from two well-exposed sections are studied. The sections are located northwest
(Sararu village) and southeast (Sarki village) of Amadyia district, within High Folded
Zone, in the Iraqi-Kurdistan. The Baluti Formation consists of intimately interbedded
green, gray to black shale and gray limestone with subordinate greenish gray marlstone;
those do not alternate in a repeated fashion and are not strictly described as cyclic.
Bioclastic limestone, intraclastic limestone, and peloidal limestone interbedded with
invasively yellowish-gray shaley mudstone and fissile shale lithologies which are
interpreted as slope and basinal units deposited in deeper water. Storms were a dominant
factor in initializing down-slope transport from shallower-water settings. Polymictic
limestone conglomerate and shallow-water-derived limestone, fossils and siliciclastic
grains indicate that depositional slopes were steep enough at times to allow considerable
transport from up-slope areas. The bioclastic and peloidal limestones then locally turn
into the nodular limestone through early diagenetic modification in deep water.
Petrographic evidences indicated that these deposits have undergone both shallow and
deep-marine diagenesis with slightly influence of vadose and meteoric diagenesis.
Following shallow-marine diagenesis, these intra- and bio-clasts were transported to the
deeper part and were exposed to deep-marine water, which appear to have initiated
deepmarine diagenesis. The evidence of deep-marine diagenesis is reprecipitation of the
small amount of carbonate generated by dissolution of unstable grains (presumably
aragonitic) into newly opened molds and partially filled primary pores as clear, fine to
medium, equant calcite spar.

Key Words
Baluti Fn.,

[1] Bellen R. C. Van, Dunnington H. V., Wetzel R. and Morton D., “Lexique Stratigraphique, Interntional. Asie, Iraq”, Fascicule, 10a, Iraq. Central National deal Recherches Scientifique, Paris,
333p., (1959).
[2] Buday T., “The regional geology of Iraq. Vol. I, Stratigraphy and Paleogeography”, Dar Al-Kutub pub. Univ. of Mosul, Iraq, 445 P,(1980).
[3] Hanna M. T., " Palynology of the Upper Part of Baluti Formation (Upper Triassic) and The Nature of its Contact with the Sarki Formation (Lower Jurassic) at Amadyia District, Northern Iraq", Ph.D. thesis, University of Mosul, Mosul, Iraq, (2007).
[4] Folk, R. L., “Petrology of sedimentary rocks” Austin, Texas, Hemphill Publishing Co., 182 p., (1980).
[5] Molina J.M., Ruiz-Ortiz P.A. and Vera J.A., “Calcareous tempestites in pelagic facies (Jurassic, Betic Cordilleras, Southern Spain)”, Sedimentary Geology 109, pp. 95-109, (1997).
[6] Vierek A., “The palaeogeographical background of Late Devonian storm events in the western part of the Holy Cross Mountains (Poland)”, Geologos 19, 4, pp. 257-272, (2013).
[7] Reid R.P. and Macintyre I.G., “Microboring versus recrystallization: further: insight to the micritizationprocess”, J. Sed. Pet., 70 (1), pp. 24-28, (2000).
[8] Boggs S., Jr., “Principles of Sedimentology and Stratigraphy”, 4th edn.: Prentice Hall, Upper Saddle River, NJ, (2006).
[9] Moore C.H., “Carbonate diagenesis and porosity. Developments in sedimentology”, 46, Elsevier Amesterdam, 338 p., (1989).
[10] Flügel, E., “Microfacies of carbonate rocks. Analysis, interpretation and application”, Berlin, Springer, 976 p., (2004).
[11] Berner R. A. and Honjo S., “Pelagic sedimentation of aragonite: its geochemical significance”, Science 211, pp. 940–942., (1981).
[12] Weible R.and Friis H., “Opaque minerals as keys for distinguishing oxidizing and reducing diagenetic conditions in the lower Triassic Bunter Sandstone, North German Basin”, Sediment. Geol., v.169, pp.121-128, (2004).
[13] Tucker M. E., “Sedimentary Petrology: An Introduction to the Origin of Sedimentary Rocks” Oxford, Blackwell Science, 262 p., (2001).
[14] Aqrawi A. A. M., Goff J. C., Horbury A. D. and Sadooni F. N., “The Petroleum Geology of Iraq”, Scientific Press Ltd, 424 P., (2010).
[15] Jassim S. Z. and Goff J. C., “Geology of Iraq”, Published by Dolin, Prague and Moravian Museum, Brno. Printed in the Czech Republic, 341 P., (2006).
[16] Aigner T., “Calcareous tempestites: storm-dominated stratification in upper Muschelkalk Limestone (middle Trias, sw-germany), in ‘Cyclic and Event stratification” Einsele G. and Seilacher A., eds., New York, Heidelberg, Berlin, Springer-Verlag, 536 p., (1982).
[17] Bathurst R. G. C., “Carbonate sediments and their diagenesis” Elsevier, Amsterdam, 2nd Edition, 658p., (1975).
[18] Maclntyre I. G., Prufert-Bebout L. and Reid R. P., “The role of endolithic cyanobacteria in the formation of lithified laminae in Bahamian stromatolites”, Sedimentology, 47, pp. 915-921, (2000).
[19] Tucker M. F. and Wright V. P., “Carbonate Sedimentology”, Blackwell Scientific Publication, Oxford, London, UK, 482 p., (1990).
[20] Wilson M. E. J and Evans M. J., “Sedimentology and diagenesis of Tertiary carbonates on the Mangkalihat Peninsula, Borneo: implications for subsurface reservoir quality” Marine and
Petroleum Geology, 19, pp. 873-900, (2002).
[21] Freeman-Lynde R. P., Whitley K. E, and Lohmann K. C, “Deep-marine origin of equant spar cements in Bahama Escarpment limestones”, J. Sediment. Petrol., 56, pp.799-811,( 1986).
[22] Odin G.S. and Matter A., “De glauconiarum origine” Sedimentology, 28, pp. 611-641, (1981).
[23] Loucks R. G. and Ruppel S. C., “Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin, Texas”, AAPG Bulletin, 91, 4, pp. 579-601, (2007).