Abstract
The study area is situated in the folded zone of the Zagros Basin where sediments of the Sachun Formation (Paleocene–Lower Eocene) were deposited in a shallow marine environment and consist of interstratified carbonate, shale and evaporite. The Sachun Formation is conformably overlain by the dolomite-dominated Jahrom Formation and unconformably downlaps the Tarbur Formation carbonates (Alavi in Am J Sci 304:1–20, 2004). The Sachun Formation consists mainly of secondary gypsum, which precipitated from the hydration of precursor anhydrite rock. The succession of the Sachun Formation has been divided into three units: the lower red clastic unit, the middle evaporite unit, and the upper carbonate unit. In the middle unit gypsum, several structures are distinguished; e.g. nodular, nodular-banded, and laminated-banded lithofacies with enterolithic and chicken-wire structures. These associations were deposited in a sabkha or shallow water type of depositional environment. Petrographic investigations confirm that the evaporites of the Sachun Formation are mostly composed of secondary gypsum, with rare anhydrite relics. Five microfacies were distinguished according to the gypsum fabrics. The textural relationships of the carbonate and sulfate minerals indicate that some of these anhydrites were formed as a result of a replacement processes of carbonate sediments associated with evaporites. The textures are considered to be a by-product of anhydrite hydration, which is in turn rehydrated from primary gypsum. The evaporites indicate deposition during a regressive lowstand systems tract, whereas the carbonates indicate deposition under shallow water marine conditions during a highstand systems tract. The Sachun Formation succession deposits are in a quite stable arid climate within a rapidly subsiding basin.
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References
Afghah M, Yaghmoor Sh, Fadaian ShA (2010) Microbiostratigraphy of the Tarbur Formation in Tang-e Kooshk area (Eastern Shiraz). In: Third congress of Iran paleontology Society, pp 26–29
Alavi M (2004) Regional stratigraphy of the zagros fold thrust belt of iran and its proforeland evolution. Am J Sci 304:1–20
Alsharhan AS, Nairn AEM (2003) Sedimentary basins and petroleum geology of the middle east. Elsevier, Amsterdam, p 843
Alsharhan AS, Whittle GL (1995) Carbonate-evaporite sequences of the Late Jurassic, Southern and Southwestern Arabian Gulf. Am Assoc Petroleum Geol Bull 79:1608–1630
Aref M, Attiia O, Wali A (1997) Facies and depositional environment of the Holocene evaporites in the Ras Shukeir area, Gulf of Suez, Egypt. Sediment Geol 110:123–145
Astin TR, Rogers DA (1991) Subaqueous shrinkage cracks in the Devonian of Scotland reinterpreted. J Sediment Petrol 61(5):850–859
Bordenave ML (2002) The Middle Cretaceous to Early Miocene petroleum system in the Zagros Domain of Iran and its prospect evaluation. In: Presented at AAPG annual meeting, March 10–12, 2002, Houston, Texas
Braga JC, Martin JM, Riding R (1995) Controls on microbial dome fabric development along a carbonate-siliciclastic shelf-basin transect, Miocene, SE Spain. Palaios. 10:347–361
British Petroleum Company (1956b) Oil and gas in Southwest Iran. In: Proceedings of the 20th session, international geological congress, Mexico, Symposium sobre yacimientos de petroleo y gas, t. II pp 33–72
Butler GP (1970) Recent gypsum and anhydrite of the Abu Dhabi, Trucial Coast, Persian Gulf: an alternative explanation of origin. In: Proceedings of 3rd international salt symposium, vol 1. Northern Ohio Geological Society, Cleveland, pp 120–152
Chafetz HS, Rush PF (1994) Diagenetically altered sabkha-type Pleistocene dolomite from the Arabian Gulf. Sedimentology 41:409–442
Chafetz HS, Alicia A, Imerito-Tetzlaff A, Zhang J (1999) Stable-isotope and elemental trends in Pleistocene sabkha dolomites: descending meteoric water vs. sulfate reduction. J Sediment Res 69:256–266
El-Tabakh M, Schreiber BC, Warren JK (1998) Origin of fibrous gypsum in the Newark Rift Basin, eastern North America. J Sediment Res 68:88–99
Evans G, Kirkham A (2002) The Abu Dhabi Sabkha. In: Barth H-J, Böer B (eds) Sabkha ecosystems, pp 7–20
Gustavson TC, Hovorka S, Dutton AR (1994) Origin of satin spar veins in evaporite basins. J Sediment Res A64(1):88–94
Handford CR (1991) Marginal marine halite: sabkhas and Salinas. In: Melvin JL (ed) Evaporites, petroleum and mineral resources, vol 50. Developments in sedimentology, Amsterdam, pp 1–66
Hardie LA, Eugster HP (1971) The depositional environment of marine evaporites: a case for shallow, clastic accumulation. Sedimentology 16:187–220
Haridie LA (1967) The gypsum–anhydrite equilibrium at one atmospheric pressure. Am Mineral 52:171–199
Holiday DW (1970) The petrology of secondary gypsum rocks. A review. J Sediment Petrol 40:734–744
Hussain M, Warren JK (1989) Nodular and enterolithic gypsum: the ‘sabkhatization’ of salt flat playa, West Texas. J Sediment Petrol 64:13–24
James GA, Wynd JG (1965) Stratigraphic nomenclature of Iranian Oil Consortium Agreement Area. Am Assoc Petroleum Geol Bull 49:2182–2245
Kalantari A (1976) Microbiostratigraphy of the Sarvestan area, SW Iran. N.I.O.C Geological laboratories publications, p 129
Kasprzyk A (2005) Diagenetic alteration of Badenian sulphate deposits in the Carpathian Foredeep Basin, Southern Poland: processes and their succession. Geol Quart 49(3):305–316
Kendall AC (1981) Continental and supratidal (sabkha) evaporates. In: Walker RG (ed) Facies models. Fourth Printing, Geoscience Canada, Reprint Series 1, pp 145–157
Kendall AC (1984) Evaporites. In: Walker RG (ed) Facies models: Geoscience Reprint Series 1, Newfoundland, Canada, Geological Association of Canada, pp 259–296
Kendall AC (1989) Brine mixing in the Devonian of western Canada and its possible significance to regional dolomitization. Sediment Geol 64:271–285
Kendall AC (1992) Evaporites. In: Walker RG, James NB, (Eds), Facies Models—response to sea level change. Geological Association of Canada, St John’s, pp 375–409
Kirkland DW (2003) An explanation for the varves of the castile evaporites (upper Permian), Texas and New Mexico, USA. Sedimentology 50:898–920
Lasemi Y, Afghah M, Arzaghi S (2007) Facies analysis and sedimentary environments of Sachun Formation in Kuh-e Siah section, southeast of Sarvestan (Fars Province). Quart J Appl Geol 3:213–221
Lowenstein TK, Hardie LA (1985) Criteria for the recognition of salt-pan evaporites. Sedimentology 32:627–644
Mees F, Stoops G (2003) Circumgranular bassanite in a gypsum crust from eastern Algeria—a potential paleosurface indicator. Sedimentology 50:1139–1145
Mossop GD, Shearman DJ (1973) Origins of secondary gypsum rock. Inst Min Metall Trans (Section B) 82:147–154
Murray RC (1964) Origin and diagenesis of gypsum and anhydrite. J Sediment Petrol 34:512–523
NIOC (1979) Exploration and production affairs-National Iranian Oil Company, Geological Quadrangle map of Iran No.G-11 (Shiraz quadrangle 1:250,000 Quadrangle. National Iranian Oil Company, Tehran
Ogniben L (1955) Inverse graded bedding in primary gypsum of chemical deposition. J Sediment Petrol 25:273–281
Peryt TM (2001) Gypsum facies transitions in basin-marginal evaporites: middle Miocene∓ (Badenian) of west Ukranie. Sedimentology 48:1103–1119
Plummer PS, Gostin VA (1981) Shrinkage cracks-desiccation or synaeresis. J Sediment Petrol 51:1147–1156
Pursar BH (1973) The Persian Gulf: Holocene carbonate sedimentation and diagenesis in a shallow epicontinental Sea. Springer, Berlin, p 471
Richardson WA (1920) The fibrous gypsum of Nottinghamshire. Mineral Mag 91:77–95
Schreiber BC, El Tabakh M (2000) Deposition and early alteration of evaporites. Sedimentology 47:215–238
Shabafrooz R, Mahboubi A, Moussavi-Harami R (2010) Dolomitization and evaporate mineralization of Sachun Formation at type locality (SE Shiraz). Iran J Crystallogr Mineral 17(4):609–620
Shearman DJ (1966) Origin of marine evaporites by diagenesis. Inst Min Metall Trans (Section B) 75:208–215
Shearman DJ (1978) Evaporites of coastal sabkhas. In: Dean WE, Schreiber BC (eds) Marine evaporites: SEPM short course no. 4 Oklahoma City 1978: Tulsa, Society of Economic Paleontologists and Mineralogists, pp 6–42
Shearman DJ (1985) Syndepositional and late diagenetic alteration of primary gypsum to anhydrite. In: Schreiber BC, Harner HL (eds) Sixth international symposium on salt. Salt Institute, vol 1, pp 41–50
Shearman DJ, Mossop G, Dunsmone H, Martine H (1972) Origin of gypsum veins in hydraulic fracture. Trans Inst Min Metall Appl Earth Sci 81B:149–155
Stewart AJ (1979) A barred-basin marine evaporite in the upper Proterozoic of the Amadeus Basin, central Australia. Sedimentology 26:33–62
Testa G, Lugli S (2000) Gypsum anhydrite transformation in messinion evaporites of central Tuscany (Italy). Sediment Geol 130:249–268
Till R (1979) Arid shorelines and evaporites. In: Reading HG (ed) Sedimentary environments and facies. Blackwell Scientific Publications, Oxford, pp 178–206
Wanas HA (2002) Petrography, geochemistry and primary origin of spheroidal dolomite from the Upper Cretaceous/Lower Tertiary Maghra El-Bahary Formation at Gabal Ataqa, Northwest Gulf of Suez, Egypt. Sediment Geol 151:211–224
Warren JK (1991) Sulfate dominated sea-marginal and platform evaporite settings: sabkhas and salinas, mudflats and salterns. In: Melvin JL (ed) Evaporites, petroleum and mineral resources, vol 50. Developments in sedimentology, Amsterdam, pp 69–187
Warren JK (1999) Evaporites—their evolution and economics. Blackwell, Oxford, p 438
Warren JK (2000) Dolomite: occurrence, evolution and economically important associations. Earth Sci Rev 52:1–81
Warren JK (2006) Evaporites: sediments, resources and hydrocarbons. Springer, Heidelberg, p 1036
West IM (1964) Evaporite diagenesis in the lower Purbeck beds of Dorset. In: Proceedings of the Yorkshire geological society, vol 34, pp 315–330
West IM (1965) Macrocell structure and enterolithic veins in British Purbeck gypsum and anhydrite. In: Proceedings of the Yorkshire geological society, vol 35, pp 47–58
Acknowledgments
This study forms part of Solmaz Azaghi’s PhD thesis at the Islamic Azad University of Science and Research in Tehran, Iran. The authors would like to thank the Geological Survey of Iran, Shiraz branch for sponsoring field and laboratory facilities in this research. Special thanks are also extended to Mehdi Arzaghi, Lilian Arzaghi and Dirk Ross for making language corrections and their helpful comments.
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Arzaghi, S., Khosrow-Tehrani, K. & Afghah, M. Sedimentology and petrography of Paleocene–Eocene evaporites: the Sachun Formation, Zagros Basin, Iran. Carbonates Evaporites 27, 43–53 (2012). https://doi.org/10.1007/s13146-011-0082-1
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DOI: https://doi.org/10.1007/s13146-011-0082-1