Advanced Applied Geology

Advanced Applied Geology

Structural analysis of a blind thrust sheet and its impact on the fluvial system: a case study in north of the Dezful Embayment (Zagros Belt, SW Iran).

Authors
Seyed Morteza Mousavi 1
Fariba Zahmati 2
Iraj Abdollahie Fard 3
Mohammad Seraj 4
1 Associate professor,Department of Geology, University of Birjand
2 Student ,Department of Geology, University of Birjand, Iran
3 Exploration Directorate of NIOC.Tehran,Iran.
4 National Iranian South oil Company (NISOC), Ahvaz, Iran.
10.22055/aag.2025.48260.2481
Abstract
Abstract
The studied area is considered as a part of Zagros foreland basin system, where detrital sediments during Miocene to the present have been accumulated within it. In this basin, fault-related folds with intricate geometries in foreland systems are complex structural traps.
Results show that a meandering fluvial system was dominant in the north of Dezful Embayment during Miocene. Increasing intensity of tectonic activity caused thrusting along the Balarud Fault Zone (BFZ) since Late Miocene, and it led to increasing surface slope. Therefore, a braided fluvial system has been dominated in the area with deposition of the coarse- to very coarse-grained . Also, the major river directions had been changed to present-day north-south by the young Zagros tectonic activities (Late Alpine). Then, the north of Dezful Embayment became a large depocenter for the syn-orogenic fluvial deposits. This huge trough played an important role in the petroleum system evolution of the area. This thrust fault is clearly detectable in wells and seismic data, showing repeated units. There are not enough evidences to propose this fault as a sub-order of the Balarud Fault Zone. Depth maps and maximum curvature attributes of the fault surface reveal NE-SW lineaments, indicating possible fault slip direction. Thickness maps of hanging and footwall blocks confirm a dominant reverse fault component with minimal strike-slip displacement. The thrust sheet's curvilinear geometry suggests folding during the latest stage of the Zagros Orogeny,
Keywords
Keywords: foreland basin system
fluvial depositional system
Dezful Embayment
fan and intra-fan facies
displacement detection
Subjects
Alavi, M., 1994. Tectonics of the zagros orogenic belt of iran: new data and interpretations. Tectonophysics 229(3-4), 211–238. https:// doi:10.1016/0040-1951(94)90030-2.
Allen, M.B., Talebian, M., 2011. Structural variation along the Zagros and the nature of the Dezful Embayment. Geological Magazine 148(5-6), pp.911-924. https://. doi:10.1017/s0016756811000318
Berberian, M., King, G.C.P., 1981. Towards a paleogeography and tectonic evolution of Iran. Canadian Journal of Earth Sciences 18(2), 210–265. https://doi:10.1139/e81-019.
Burbank, D.W., 1992. Causes of recent Himalayan uplift deduced from deposited patterns in the Ganges Basin. Nature 357, 680–682. https://doi.org/10.1038/357680a0.
Decelles, P.G., Hertel, F., 1989. Petrology of fluvial sands from the Amazonian foreland basin. Peru and Bolivia. Geological Society of America Bulletin 101(12), pp.1552-1562. https://doi.org/10.1130/0016-7606(1989)101<1552:POFSFT>2.3.CO;2.
Decelles, P.G., Giles, K.A. 1996. Foreland basin systems. Basin research 8(2), pp.105-123. https://doi.org/10.1046/j.1365-2117.1996.01491.x.
Derikvand, B., Alavi, S.A., Abdollahie Fard, I., Hajialibeigi, H., 2018. Folding style of the Dezful Embayment of Zagros Belt: Signatures of detachment horizons, deep-rooted faulting and syn-deformation deposition. Mar. Pet. Geol 91, 501–518. https://doi.org/10.1016/j.marpetgeo.2018.01.030.
Dickinson, W.R., Suczek, C.A., 1979. Plate tectonics and sandstone compositions. Aapg Bulletin 63(12), pp.2164-2182. https://doi.org/10.1306/2F9188FB-16CE-11D7-8645000102C1865D.
Emami, H., Vergés, J., Nalpas, T., Gillespie, P., Sharp, I., Karpuz, R., Blanc, E.P., Goodarzi, M.G.H., 2010. Structure of the Mountain Front Flexure along the Anaran anticline in the Pusht-e Kuh Arc (NW agros, Iran): Insights from sand box models. Geol. Soc. Spec. Publ 330, 155–178. https://doi.org/10.1144/SP330.9.
Fakhari, M.D., Axen, G.J., Horton, B.K., Hassanzadeh, J., Amini, A., 2008. Revised age of proximal deposits in the Zagros foreland basin and implications for Cenozoic evolution of the High Zagros. Tectonophysics 451(1-4), 170-185. https://doi.org/10.1016/j.tecto.2007.11.064
Falcon, N.L., 1969. Problems of the relationship between surface structure and deep displacements illustrated by the Zagros. Range, 9-21. https:// doi: 10.1144/GSL.SP.1969.003.01.02.
Gérard, B., Rouby, D., Huismans, RS., Robin, C., Fillon, C., Braun, J., 2023. Impact of inherited foreland relief on retro-foreland basin architecture. Journal of Geophysical Research: Solid Earth 128. https://doi.org/10.1029/2022JB024967.
Lin, M.L., Chung, C.F., Jeng, F.S., 2006. Deformation of overburden soil induced by thrust fault slip. Eng. Geol. 88, 70–89. https://doi.org/10.1016/j.enggeo.2006.08.004
Motiei, H., 1993. Stratigraphy of Zagros, Treatise on the geology of Iran. Geological Survey of Iran, Tehran [in Persian].
Navabpour, P., Angelier, J., Barrier, E., 2010. Mesozoic extensional brittle tectonics of the Arabian passive margin, inverted in the Zagros collision (Iran, interior Fars). Geol. Soc. Spec. Publ. 330, 65–96. https://doi.org/10.1144/SP330.5.
Nissen, E., Tatar, M., Jackson, J.A., Allen, M.B., 2011. New views on earthquake faulting in the Zagros fold-and-thrust belt of Iran. Geophys. J. Int. 186, 928–944. https://doi.org/10.1111/j.1365-246X.2011.05119.x
Pirouz, M., Avouac, J.P., Hassanzadeh, J., Kirschvink, J.L., Bahroudi, A., 2017. Early Neogene foreland of the Zagros, implications for the initial closure of the Neo-Tethys and kinematics of crustal shortening. Earth and Planetary Science Letters 477, 168–182. https://doi.org/10.1016/j.epsl.2017.07.046.
Pirouz, M., 2018. Post-collisional deposits in the Zagros foreland basin: Implications for diachronous underthrusting 107, 1603-1621. https://doi.org/10.1007/s00531-017-1561-y.
Razavi Pash, R.R., Sarkarinejad, K., Sherkati, S., Motamedi, H., 2021. Analogue model of the Bala Rud Fault, Zagros-an oblique basement ramp in a fold‑and‑thrust belt. Int. J. Earth Sci. https://doi.org/10.1007/s00531-21-01987-0.
 Schwab, F.L., Allen, P.A., Homewood, P., 1986. Sedimentary signatures of foreland basin assemblages: real or counterfeit., Foreland basins 8, 395-410. https://doi.org/10.1002/9781444303810.ch21.
Sepehr, M., Cosgrove, J.W., 2004. Structural framework of the Zagros Fold-Thrust Belt, Iran. Mar. Pet. Geol. 21, 829–843. https://doi.org/10.1016/j.marpetgeo.2003.07.006.
Sherkati, S., Letouzey, J., Frizon De Lamotte, D., 2006. The Central Zagros fold-thrust belt (Iran): new insights from seismic data, field observation, and sandbox modeling. Tectonics 25, TC4007. https://doi.org/10.1029/2004TC001766.
Vergés, J., Casini, G., Ruh, J., Cosgrove, J., Sherkati, S., Najafi, M., Casciello, E., Saura, E., Abdollahie Fard, I., Piryaei, A., Sepehr, M., Frizon de Lamotte, D., Letouzey, J., Goodarzi, H., Soleimany, B., Jahani, S., 2024. Structural Style and Timing of NW-SE Trending Zagros Folds in SW Iran: Interaction with North-South Trending Arabian Folds and Implications for Petroleum Geology, Journal of Petroleum Geology 47(1), 1-70. https://doi.org/10.1111/jpg.12850.
Yaghoubi, A., Dusseault, M.B., Leonenko, Y., 2023. Stress Variation around the Balarud Lineament in the Zagros Fold and Thrust Belt and its Implication for Reservoir Geomechanics. 57th US Rock Mech. Symp. https://doi.org/10.56952/ARMA-2023-0270
Yaghoubi, A., Mahbaz, S., Dusseault, M.B., Leonenko, Y., 2021. Seismicity and the state of stress in the dezful embayment, Zagros fold and thrust belt. Geoscience 11, 1–22. https://doi.org/10.3390/geosciences11060254.
Advanced Applied Geology
Volume 15, Issue 2
Summer 2025
Pages 68-83