Diagenetic history of Mozduran Formation and the relation between dolomditization and depositional sequences in Dasht-e-Gonbad area, west of the Kopet-Dagh basin

Document Type : مقالات پژوهشی

Authors

• Zahra Pourheidar ¹
• Mohammad Hossein Mahmudy-Gharaie ²
• Asadollah Mahboobi ²
• Reza Moussavi-Harami ²

¹ Department of Geology, Faculty of Science, Ferdowsi university of Mashhad, Mashhad, Iran

² Ferdowsi University of Mashhad

10.22067/sed.facies.v9i1.34294

Abstract

Introduction
In this study, the Upper Jurassic carbonate strata in the Kopet-Dagh sedimentary basin (Mozduran Formation) has been investigated in the Gonbad plain in the west of Golestan Forest National Park. Mozduran Formation in the studied section is composed of muddy limestone containing chert nodules with interbeds of marl and shale that is conformably covered the shale beds of Kashaf-Rud Formation with a sharp boundary. The aim of this study is to interpret the diagenetic history of the Mozduran Formation and to interpret the relation between dolomitization and sequence stratigraphy. One of the most important applications of geochemical studies in carbonate rocks is to determine the composition of primary mineralogy, interpret sedimentary environment and depositional conditions, the palaeo temperature, alteration, differentiation of different diagenetic environments and determination of diagenetic trends (Adabi & Asadi Mehmandosti, 2008).

Material and methods
In this study, samples collected from surface section in south of Cheshmeh-Khan village and the data of Qezel-Tapeh well #2 have been used. 130 samples of limestone and dolomite and 8 samples of sandstone from Cheshmeh-Khan section (with thickness of 236 meters) and 103 samples from Qezel-Tapeh well #2 were analyzed and studied. Thin-sections stained with Alizarin Red-S, using Dickson (1965) method to differentiate calcite from dolomite. Global sea level curves presented by Haq et al. (1987) were used and compared with interpreted sea level curve for the sequence stratigraphic analysis. 4 samples of dolomite and 2 samples of pyrite were studied by scanning electron microscopy (SEM) and also analyzed by EDX. In order to study the geochemistry of Mozduran Formation in the Cheshmeh-Khan section, 20 samples (10 samples of micrite and 10 samples of dolomite) were selected for determination of the major elements (Mg and Ca) in terms of percentage and minor elements (Fe, Mn, Sr) in terms of ppm, samples were analyzed by atomic absorption (AAS).

Results and conclusion
Diagenetic studies indicate that the most important diagenetic processes affected these sediments are dolomitization, cementation, micritization, dissolution, physical and chemical compaction and neomorphism. These processes have affected sediments in three meteoric, marine and burial environments. In general, early diagenetic peocesses in marine environment include micritization, formation of isopachous cement and primary dolomite. Formation of isopachous, syntaxial and drusy cements, dissolution (formation of vugy porosity) and neomorphism have occurred at the stage of meteoric diagenesis. Last diagenetic processes (in shallow and deep burial stages) include dolomitization, mechanical compaction, stylolization and formation of fractures.
Neomorphism has seen to operate in three different processes: conversion of calcareous mud to coarse calcite crystals in mud-supported facies, replacement of calcite in aragonite grains, and converting fine-crystalline to coarse-crystalline dolomites. Based on the size and boundaries of crystals (Warren, 2000), four types of dolomite have been identified in the Mozduran Formation, including very fine-crystalline dolomite, mosaic microcrystalline dolomite, medium-crystalline dolomite and coarse- crystalline dolomite. Dolomites formed as primary and replacement in matrix and allochems. The presence of dolomite along dissolution veins and stylolite as well as coarse crystal dolomites indicate that shallow burial processes probably played an important role in the formation of these dolomites. Microcrystalline dolomite (D1) is perfectly indicative of surface conditions, low temperature and probably supratidal environment, due to very small size of crystals, the absence of fossils and the preservation of the primary sedimentary texture (Adabi, 2009). Super saturated alkaline condition with high pH are also suitable for the formation of these primary dolomite (Deng, et al., 2010).
Sibley and Gregg (1987) are believed that semi-shaped straight fabric of coarse-crystalline dolomite (D4) are the result of the slow growth of crystals at low temperatures during shallow burial and formed from recrystallization of finer crystals. Elemental analysis of the studied rocks shows that the effect of diagenic processes, specially diagenetic alteration on a semi-closed system with high water-to-rock exchange on Mozduran Formation was high and the low Sr/Mn ratio shows a high dissolution rate in the formation of dolomites (Rao & Amini, 1995). Very fine crystals of dolomite (the first type) formed in a supratidal environment (Blendinger, 2004), therefore they can form at the end of some shallowing upward sequences (third, fourth, and fifth sequences). The dispersion and abundance of fine crystals of dolomites in the upper parts of sequences represent sea level fluctuation during sedimentation (Khalifa, 2005).

Keywords: Kopet-Dagh; Mozduran Formation; Cheshme-Khan village; Qezel-Tapeh2 well; Diagenesis; Geochemistry.

Reference
Adabi, M.H., & Asadi Mehmandosti, E., 2008. Microfacies and geochemistry of the Ilam Formation in the Tang-e-Rashid area, Izeh, SW Iran. Journal of Asian Earth Sciences, 33: 267-277.
Adabi, M.H., 2009. Multistage dolomitization of Upper Jurassic Mozduran Formation, Kopet-Dagh Basin, NE Iran. Carbonates and Evaporites, 24: 1: 16-32.
Blendinger, W., 2004. Sea level changes versus hydrothermal diagenesis: origin of Triassic carbonate platform cycles in the Dolomites, Italy. Sedimentary Geology, 169: 21–28.
Deng, S., Dong, H., Lv, G., Jiang, H., Yu, B., Bishop, M.E., 2010. Microbial dolomite precipitation using sulfate reducing and halophilic bacteria: Results from Qinghai Lake, Tibetan Plateau, NW China. Chemical Geology, 278: 151–159.
Dickson, J.A.D., 1965. A modified staining technique for carbonate in thin section. Nature, 205: 587.
Haq, B.U., Hardenbol, J., Vail, P.R., 1987. Chronology of fluctuating sea levels since the Triassic. Science, 235: 1156-1166.
Khalifa, M.A., 2005. Lithofacies, diagenesis and cyclicity of the ‘Lower Member’ of the Khuff Formation (Late Permian), Al Qasim Province, Saudi Arabia. Journal of Asian Earth Sciences, 25: 719–734.
Rao, C.P., & Amini, Z.Z., 1995. Faunal relationship to grain-size, mineralogy and geochemistry in recent temperate shelf carbonate, western Tasmania, Australia. Carbonates and Evaporites, 10: 114-123.
Sibley, D.F. & Gregg, J.M., 1987, Classification of dolomitic rock textures, J. Sed. Petrol, 57: 957-965.
Warren, J., 2000, Dolomite: occurrences, evolution and economical important association. Earth Science Review, 52: 1-87.

Keywords

• Kopet-Dagh
• Mozduran Formation
• Cheshme-Khan village
• Qezel-Tapeh2 well
• diagenesis
• Geochemistry

---

References

آقانباتی، س.ع.، 1383. زمین‌شناسی ایران. سازمان زمین‌شناسی و اکتشافات معدنی کشور، 586 ص.

آقایی، س.ع.، موسوی حرمی، ر.، محبوبی، ا.، 1382. تاریخچه و محیط رسوب‌گذاری سازند مزدوران در غرب آق‌دربند. پایان‌نامه کارشناسی ارشد، دانشگاه فردوسی مشهد، 237 ص.

آل‌طه، ح.، موسوی حرمی، س.ر.، محبوبی، ا.، نجفی، م.، 1383. لیتواستراتیگرافی و تاریخچه رسوب‌گذاری رسوبات سیلیسی آواری سازند مزدوران در شرقی‌ترین بخش حوضه کپه‌داغ. هشتمین همایش انجمن زمین‌شناسی ایران.

افشارحرب، ع.، 1373. زمین شناسی ایران: زمین‌شناسی کپه‌داغ. سازمان زمین‌شناسی و اکتشافات معدنی کشور، 275 ص.

پورحیدر، س.ز.، 1391. تاریخچه رسوب‌گذاری و پس از رسوب‌گذاری سازند مزدوران در دشت گنبد، غرب کپه‌داغ. پایان‌نامه کارشناسی ارشد، دانشگاه فردوسی مشهد، 120 ص.

پورحیدر، س.ز.، محبوبی، ا.، محمودی قرائی، م.ح.، موسوی حرمی، س.ر.، 1393. تأثیر نوسانات سطح آب دریا بر رخساره‌های رسوبی در سازند مزدوران، غرب کپه‌داغ. فصلنامه علوم زمین، 94: 275-286.

رحیم‌پور بناب، ح. ،1384. سنگ‌شناسی کربناته (ارتباط دیاژنز و تکامل تخلخل). دانشگاه تهران، 487 ص.

سلامتی، ر.، شافعی، ا.، کریمی، ح.، وزیری، ح.، 1380. نقشه زمین‌شناسی چهارگوش 1:100000 رباط قره‌بیل. سازمان زمین‌شناسی و اکتشافات معدنی کشور.

موسوی حرمی، ر.، 1368. لیتواستراتیگرافی و تاریخچه رسوب‌گذاری ژوراسیک فوقانی (آکسفوردین- کیمریجین) در محدوده کل‌ملک‌آباد در جنوب غرب آق‌دربند. هشتمین گردهمایی علوم زمین، سازمان زمین‌شناسی و اکتشافات معدنی کشور، صص 8-6.

نجفی، م.، فیضی، ا.، موسوی حرمی، ر.، 1378. لیتواستراتیگرافی و میکروفاسیس سازند مزدوران یک در شمال مشهد و معرفی آن به عنوان سازند خانه‌زو (باتونین - کالووین). سومین همایش انجمن زمین‌شناسی ایران.

Adabi, M.H., & Asadi Mehmandosti, E., 2008. Microfacies and geochemistry of the Ilam Formation in the Tang-e-Rashid area, Izeh, SW Iran. Journal of Asian Earth Sciences, 33: 267-277.

Adabi, M.H., & Rao, C.P., 1991. Petrographic and geochemical evidence for original aragonitic mineralogy of Upper Jurassic carbonate (Mozduran Formation) Sarakhs area, Iran. Sedimentary Geology, 72: 253-267.

Adabi, M.H., 2009. Multistage dolomitization of Upper Jurassic Mozduran Formation, Kopet-Dagh Basin, NE Iran. Carbonates and Evaporites, 24: 1: 16-32.

Allan, J.R., & Wiggins, W.D., 1993. Dolomite reservoir: geochemical techniques for evaluating origin and distribution. American Association of Petroleum Geologists, Containing Education Course Notes Series, 36: 1-136.

Blendinger, W., 2004. Sea level changes versus hydrothermal diagenesis: origin of Triassic carbonate platform cycles in the Dolomites, Italy. Sedimentary Geology, 169: 21–28.

Deng, S., Dong, H., Lv, G., Jiang, H., Yu, B., & Bishop, M.E., 2010. Microbial dolomite precipitation using sulfate reducing and halophilic bacteria: Results from Qinghai Lake, Tibetan Plateau, NW China. Chemical Geology, 278: 151–159.

Dickson, J.A.D., 1965. A modified staining technique for carbonate in thin section. Nature, 205: 587.

Dunham, R.J., 1962. Classification of carbonate rocks according to depositional texture. American Association of Petroleum Geologists Bulletin, 1: 108-121.

Gregg, J.M., & Shelton, K.L., 1990. Dolomitization and dolomite neomorphism in the back reef facies of the Bonnetere and Davis Formations (Cambrian), southeastern Missouri. Journal of Sedimentary Petrology, 60: 539-562.

Haq, B.U., Hardenbol, J., & Vail, P.R., 1987. Chronology of fluctuating sea levels since the Triassic. Science, 235: 1156-1166.

Hood, S.D., Nelson, C.S., & Kamp, P.J.J., 2004. Burial dolomitisation in a non-tropical carbonate petroleum reservoir: the Oligocene, Tikorangi Formation, Taranaki Basin, New Zealand. Sedimentary Geology, 172: 117-138.

Iannace, A., Capuano, M., & Galluccio, L., 2011. Dolomites and dolomites in Mesozoic platform carbonates of the Southern Apennines: Geometric distribution, petrography and geochemistry. Palaeogeography, Palaeoclimatology, Palaeoecology, 310: 324–339.

Kalantari, A., 1969. Foraminifera from the middle Jurassic-Cretaceous successions of Kopet-Dagh region (NE-Iran). National Iranian Oil Company, Exploration and Production, Geological Laboratory Publication 3, Tehran (Ph.D. thesis, London University). 298 p.

Khalifa, M.A., 2005. Lithofacies, diagenesis and cyclicity of the Lower Member of the Khuff Formation (Late Permian), Al Qasim Province, Saudi Arabia. Journal of Asian Earth Sciences, 25: 719–734.

Khalifa, M.A., Abou El Ghar, M.S., & El Belasy, M., 2003. Lithofacies, sequence stratigraphy and depositional history of the Abu Ghusun and Um Mahara formations (Oligo-Miocene), Ras Banas, Red Sea. The Third International Conference on the Geology of Africa, Assiut University IB, pp. 801-824.

Knauth, L.P., 1979. A model for the origin of chert in limestone. Geology, 7: 274-277.

Lasemi, Y., 1995. Platform carbonate of Upper Jurassic Mozduran Formation in the Kope-Dagh Basin, NE Iran, facies, Paleoenvironments and sequences. Sedimentary Geology, 99: 151-164.

Mahboubi, A., Moussavi-Harami, R., Carpenter, S.J., Aghaei, A., & Collins, L.B., 2010. Petrographical and geochemical evidences for paragenetic sequence interpretation of diagenesis in mixed siliciclastic-carbonate sediments: Mozduran Formation (Upper Jurassic), south of Agh-Darband, NE Iran. Carbonates and Evaporites, 25: 231-246.

Mazullo, S.J., 1992. Geochemical and Neomorphic alternation of dolomite: a review. Carbonates and Evaporites, 7: 21-37.

Meister, P., Bernasconi, S.M., Vasconcelos, C., & McKenzie, J.A., 2008. Sea level changes control diagenetic dolomite formation in hemipelagic sediments of the Peru Margin. Marine Geology, 252: 166-173.

Pettijohn, F.J., Potter, P.E., & Siever, R., 1987. Sand and sandstone. Springer-Verlag, New York, 553p.

Railsback, L.B., & Hood, E.C., 2001. A survey of multi-stage diagenesis and dolomitization of Jurassic limestones along a regional shelf-to-basin transect in the Ziz Valley, Central High Atlas Mountains, Morocco. Sedimentary Geology, 139: 285-317.

Rao, C.P., & Amini, Z.Z., 1995. Faunal relationship to grain-size, mineralogy and geochemistry in recent temperate shelf carbonate, western Tasmania, Australia. Carbonates and Evaporites, 10: 114-123.

Rao, C.P., 1991. Geochemical differences between subtropical (Ordovician), cool-temperate (recent and Pleistocene) and subpolar carbonates, Tasmania, Australia. Carbonates and Evaporites, 6: 83-106.

Reuning, L., Reijmer, J.J.G., & Betzler, C., 2002. Sedimentation cycles and their diagenesis on the slope of a Miocene carbonate ramp (Bahamas, ODP Leg 166). Marine Geology, 185: 121-142.

Scholle, P.A., & Ulmer-Scholle, D.S., 2003. A Color Guide to the Petrography of Carbonate Rocks: Grains, textures, porosity, diagenesis. American Association of Petroleum Geologists publishing, 470p.

Sibley, D.F., & Gregg, J.M., 1987. Classification of dolomitic rock textures. Journal of Sedimentary Petrology, 57: 957-965.

Taylor, K.G., & Macquaker, J.H.S., 2000. Early diagenetic pyrite morphology in a mudstone-dominated succession: the Lower Jurassic Clevland Ironstone Formation, eastern England. Sedimentary Geology, 131: 77-86.

Warren, J., 2000. Dolomite: occurrences, evolution and economical important association. Earth Science Review, 52: 1-87.

Wilkinson, B.H., Owen, R.M., & Caroll, A.R., 1985. Submarine hydrothermal weathering, global eustasy and carbonate polymorphism in Phanerozoic marine oolites. Sedimentary petrology, 55: 932-947.

Wilson, M.E.J., & Evans, M.J., 2002. Sedimentology and diagenesis of Tertiary carbonates on the Mangkalihat Peninsula, Borneo: implications for subsurface reservoir quality. Marine and Petroleum Geology, 19: 873–900.

Yassini, I., 1970. Etude Paleontologique du sodage QT-2, National Iranian oil company. Final Paleontological Report, 212: 1-25.

Yoo, C.M., & Lee, Y., 1998. Origin and modification of early dolomites in cyclic shallow platform carbonates, Yeongheung Formation (Middle Ordovician), Korea. Sedimentary Geology, 118: 141–157.

Zenger, D.H., & Dunham, J.B., 1988. Dolomitization of Siluro-Devonian limestones in a deep core (5,350 m), Southeastern New Mexico. In: Shukla, V., & Baker, P.A., (eds.), Sedimentology and Geochemistry of Dolostones. Special Publication of Society Economical and Paleontological Mineralogist, 43: 161-174.