Analysis on geochemistry of oil shales of the Sargelu formation in central Zagros

Document Type : Research Paper


1 Department of Geology, Behbahan Branch, Islamic Azad University, Behbahan, Iran

2 Department of Geology, Ahvaz Branch, Islamic Azad University, Ahvaz , Iran



To investigate the geochemical features of oil shales located in the vicinity of Zardkuh Bakhtiyari (Central Zagros) a section was selected where the sediments have cropped out. The precise location is at the Asal Keshan (AK) in the west of Chaharmahal and Bakhtiyari Province (CMBP). The sediments belong to the Jurassic Sargelu Formation and are composed of black to dark brown shales. The lower boundary is continuous and interfingering with the Neyriz Formation although with the upper formation where lies the Fahliyan Formation the boundary is discontinuous and unconformable. The oil shales in the area have formed at deep sea and in reduction conditions. Notwithstanding, they have never been able to develop oil due to a lack of continuous deposition and high temperature, which the latter is greatly required for oil maturing and development. The sole method to transform kerogen embedded in these shales to oil is Rock-Eval Pyrolysis. Some 10 samples taken from the shales were analyzed by the Rock-Eval Pyrolysis. The result was 9 variables by which diagrams of Tmax, TOC, kerogen type and hydrocarbon generation were constructed. The kerogen is predominantly of II variety. Hydrocarbon generation is restricted to crude oil of good to great oil-generating potential. the data obtained from XRF and ICP geochemical analyses showed that the number of heavy metal indices (NI, Pb, Rb, Sr, V, W, Zr, Zn) and trace elements (Ba, Ce, Co, Cr, Cu, Th, Nb, Ni, Rb, Sr, Mo, U), as well as the percentage of metallic and non-metallic oxides of Sio2, Al2o3, Na2o, Mgo, K2o, Tio2, Mno, Cao, P2o5, Fe203 inside the oil shales, were high. Therefore, the above shales have a dual economic value, which with the increasing reduction of oil and gas energy resources, and minerals can be of special importance in the future in terms of energy and minerals.


[1] A. Aboulkas and K. Elharfi, Study of the kinetics and mechanisms of thermal decomposition of Moroccan Tarfaya oil shale and its kerogen, Oil Shale 25 (2008), no. 4, 426–443.
[2] B. Asgari Pirbalouti and M. Moayeripor, Geochemical study of oil shales Sargelo Formation in Kuh-e Kaino section (northern Masjed Soleiman), Iran, Open J. Geo. 7 (2017), 83–92.
[3] F. Behar, V. Beaumont, and H.D.B. Penteado, Rock-Eval 6 technology: performances and developments, Oil Gas Sc. Technol.-Rev. 56 (2001), no. 2, 111–134.
[4] M. Fereidoni, M. Lotfi, N. Rashidnejad Omran, and M. Rashidi, Evaluate geochemical and trace elements of Qalikuh oil shale (southwest Aligudarz) using elemental analysis and RockEval pyrolysis, Sci. Quart. J. Geosci. 25 (2016), no. 98, 171–180.
[5] X. Fu, J. Wang, Y. Zeng, J. Cheng, and F. Tan, Origin and mode of occurrence of trace elements in marine oil shale from the Shengli River Area, Northern Tibet, China, Oil Shale 28 (2011), no. 4, 487.
[6] A.C. Hutton, Petrographic classification of oil shales, Int. J. Coal Geol. 8 (1987), no. 3, 203–231.
[7] M.J. Kotorba, D. Wieclaw, P. Kosakowski, J. Zacharski and A. Kowalski, Evaluation of source rock and petroleum potential of Middle Jurassic strata in the south-eastern part of Poland, Prezeglad Geo. 51 (2003), 1031–1040.
[8] E. Lafargue, F. Maraquis, and D. Pillot, Rock-Eval applications in hydrocarbon exploration, production, and soil contamination studies, Revue Inst. Francais Petrole 53 (1998), 421–437.
[9] Y. Ma and S. Li, The mechanism and kinetics of oil shale pyrolysis in the presence of water, Carbon Resources Conver. 1 (2018), 160–165.
[10] A. Ots, Estonian oil shale properties and utilization in power plants, Energetika 53 (2007), no. 2, 8–18.
[11] K.E. Peters, Guidelines for evaluating petroleum source rock using programmed pyrolysis, American Assoc. Petrol. Geo. Bull. 70 (1986), 318–329.
[12] K.E. Peters and M.R. Cassa, Applied source-rock geochemistry, In: L.B. Magoon and W.G. Dow (Eds.), The petroleum system. From source to trap, American Association of Petroleum Geologists, Tulsa, 1994.
[13] A. Pourshaban Liaoli, M. Yazdi, M.H. Adabi, and M. Daryabandeh, Factors affecting trace elements enrichment and its interaction with organic materials in Qalikouh oil shale, Lorestan, western Iran, Appl. Sediment. J. 9 (2022), no. 18, 76–96.
[14] J. Stocklin, Structural history and tectonics of Iran; A review, AAPG Bull. 52 (1968), 1229–1258.
[15] S.R. Taylor and S.H. McLennan, The Continental Crust: Its Composition and Evolution, Blackwell, Oxford, 1985.
[16] K.E. Urov and A.I. Sumberg, Characteristics of Oil Shales and Shale-Like Rocks of Known Deposits and Outcrops, Estonian Acad. Pub., 1999.
[17] C.L. Wilkerson, Trace metal composition of Green River retorted shale oil, Fuel 61 (1982), 63–70.
[18] M. Zahedi, J. Vaezipur, and M. Rahmati Ilkhchi, Geological Map of Shahrekurd, scale 1–250000 (one sheet), Geological Survey of Iran, 1993.

Articles in Press, Corrected Proof
Available Online from 04 May 2024
  • Receive Date: 26 January 2022
  • Accept Date: 27 April 2022