Viscosity estimates of salt in the Hormuz and Namakdan salt diapirs, Persian Gulf

Abstract

The parabolic surface profiles of the Hormuz and Namakdan salt diapirs in the Persian Gulf suggest that they have been extruding with Newtonian viscous rheologies for the last 104 years. We derive velocity profiles for these diapirs, neglecting gravitational spreading and erosion/dissolution while assuming incompressible Newtonian rheology of the salt. Fitting known rates of extrusion at specific points in its elliptical cross-section, the dynamic viscosity of the salt of the Hormuz diapir is found to range between 1018 and 1021 Pa s. Approximating its sub-circular cross-section to a perfect circle, the range of viscosity of the salt of the Namakdan diapir is obtained as 1017–1021 Pa s. These calculated viscosities fall within the range for naturally flowing salts elsewhere and for other salt diapirs but are broader than those for salts with Newtonian rheology deforming at room temperatures. The salts of the Hormuz and Namakdan diapirs are expected to exhibit a broader range of grain size, which matches the limited existing data.

Implications of channel flow analogue models for extrusion of the Higher Himalayan Shear Zone with special reference to the out-of-sequence thrusting

“…Neither the present models nor any other published (analogue) models can take into account this change (e.g. Ramberg 1981;Koyi 1991;Koyi 1997;Talbot and Aftabi 2004;Mukherjee 2010c;Mukherjee et al 2010;Mukherjee and Mulchrone 2011). The second important constraint worth mentioning is that since controlled removal of the extruded PDMS was impractical, the extruding PDMS was allowed to gravity spread without any erosion.…”

“…We assume the acceleration due to gravity during the time of deformation of the prototype HHSZ to be the same as at present as usual in all modelling of tectonics on Earth-analogue or numerical (e.g. Ramberg 1981;Koyi 1991;Koyi 1997;Beaumont et al 2001;Talbot and Aftabi 2004;Mukherjee et al 2010;Mukherjee and Mulchrone 2011).…”

Structural model of the Balkassar area, Potwar Plateau, Pakistan

“…A similar Jurassic salt mobilization phenomenon occurs in the Infracambrian-Cambrian Ara Formation of the Huqf Group on the Arabian Plate (Murris 1980). Furthermore, similar mobilization of the Harmos and Namakdan salt diapirs is observed in the Persian Gulf (Mukherjee et al 2010). A likewise deep erosion, faulting, tilting of strata are observed in the Indian basins that marks post-Early Norian hiatus (Mukhopadhyay et al 2010;Iqbal et al 2014b).…”

Stratigraphy of Oligocene–Miocene salt deposits in the SE Persian Gulf

“…Mukherjee et al (2010) pointed out the estimated range of viscosities calculated for the salts of the Hormuz diapirs is broader than that for Newtonian salts and higher than that for the average value of salt. The estimated range of diapirs viscosities can be useful for tectonic modelling (Mukherjee et al 2010). The diameters of salt diapirs usually vary between about 1 and 15 km (Kent 1958).…”