Kuh-e-namak salt diapir in Iran | Salt diapirs are typically developed in e.g. deformed epicontinental basins with basal salt layer in the sedimentary sequence (e.g. Zagros basin, Iran). The salt diapirs are often associated with extensive oil traps and their shapes and evolution is being extensively studied by research groups of oil-companies. We are rather interested in the microscale processes of salt deformation responsible for its longtime viscous flow.
The selected salt diapir in southern Iran (Kuh-e-Namak) probably represents the most well exposed salt dome, which is still active. It pierces the crest of a WNW-ESE trending “whale-back” anticline, where the anticline is cross-cut by a NNW-SSE trending deep seated Kazerun fault (Talbot, 1979). The Hormuz salt (precambrian to cambrian in age) rises from the basal layer through a 5 km thick phanerozoic sedimentary sequence and flows down on both flanks of the anticline. The lateral salt motion on Kuh-e-Namak was measured to be on the order of metres per year (Talbot and Jarvis, 1984), however it must be much slower according to more recent and accurate measurements done on diapirs on islands in Persian gulf (Bruthans et al., 2006). It is interesting that salt domes resemble in shape some volcanic domes, but their times of emplacement differ by several orders (10 000 - 1 000 000 yrs for salt, only few months for volcanic domes). The previsously horizontally layered salt sequence has been mobilized in permian due to extensional deformation controlled by deep-seated Kazerun fault (opening of the Tethys ocean). From eocene to recent the whole Zagros basin is subjected to N-S compression given by the convergence of Arabian and Iranian plates, which produces fold and thrust belts forming the Zagros mountains (Bahroudi, 2003; McQuarrie, 2004).
The salt rocks occuring on the surface shows complex fold patterns and layer alternations which have formed due to superpositon of at least 3 fold generations (Talbot, 1979; Talbot and Jacskon, 1987). In our work, we are mainly interested in the microphysical processes that are responsible for the viscous flow of salt at atmospheric conditions. Our approach comprises structural, microstructural and AMS analysis.
The Kuh-e-Namak salt dome is being investigated in close cooperation with the following geoscientific institutions: IPSG (Institute of petrology and structural geology, Prague), EOST (Ecole et Observatoire des Sciences de la Terre, Strasbourg), CGS (Czech geological Survey, Prague).
Schematic tectonic evolution of Kuh-e-Namak salt diapir (Zagros mountains, Southern Iran):
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Research team:
| Prokop Závada
| | | | | | | | | | | | Co-workers: | Karel Schulmann (EOST)
| | | | | | | | | | | | | | | | Ondrej Lexa (IPSG)
| | | | | | | | | | | | | | | | Jakub Haloda (CGS)
| | | | | | | | | | | | | | | | Patricie Týcová (CGS)
| | | | | | | | | | | | | | | | František Hrouda (IPSG, Agico, Int.)
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Abbreviations used:
IPSG (PřF UK) – Institute of petrology and structural geology; PřF UK – Faculty of Natural Sciences Charles University in Prague; EOST - Ecole et Observatoire des Sciences de la Terre, Strasbourg; CGS – Czech geological survey References cited:
Bahroudi, A. (2003). The Effect of Mechanical Characteristics of Basal Decollement and Basement Structures on Deformation of Zagros Basin, PhD Thesis, Uppsala University.
Bruthans J., Filippi M., Geršl M., Zare M., Melková J., Pazdur A., Bosák P., (2006). Holocene marine terraces on two salt diapirs in Persian Gulf (Iran): age, depositional history and uplift rates.- J. Quatern. Sci.. 21, 8: 843-857
McQuarrie, N. (2004). Crustal scale geometry of the Zagros fold–thrust belt, Iran. J. Struct. Geol.,26(3),519-535.
Talbot, C.J., (1979). Fold trains in a glacier of salt in southern Iran. J. Struct. Geol.. 1, 159-181.
Talbot, C.J., Jarvis, R.J., (1984). Age, budget and dynamics of an active salt extrusion in Iran. J. Struct. Geol., 6, 521-530.
Talbot, S.J., and Jackson, M.P.A., 1987. Internal kinematics of salt diapirs. Bull. Amer. Assoc. Petrol. Geol., 9, 1068-1093.
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