Dead or alive salt diapirs!

Category Tectonic & Seismotectonic
Group GSI.IR
Location 23th symposium on geosciences
Holding Date 05 May 2008

Abstract:
      The complexity of deformation arises from the very different mechanical properties of salt and sediments in salt Tectonics. Salt acts as a geologic lubricant: it is weak and ductile and behaves like a viscous fluid (in deeper parts) and semi viscous in surface. For this reason, the commonest structures within the salt are flow folds (with or without fracture), which deform the original evaporate layering into complex refolded folds. The rock deforms readily because it undergoes dynamic recrystallization, which continuously removes the effects of strain from the fabric, but not from the layering. The viscosity of salt is reduced by traces of water (less than 0.01%) and also by small grain size. In contrast to salt, the surrounding sub salt and suprasalt sediments deform as strong, brittle rocks. Large-scale folds are also visible, but in the shallow parts of sedimentary basins, these are formed by a multitude of tiny brittle displacements at mesoscopic and microscopic scales.
   The record of salt tectonics and fold and fracture network revolution such as interpretation of seismic profiles, Aerial photographs of different ages, isopach maps, and so on. A focus on Kuh-e-namak (Qum) showed that the two salt horizons may act on the hydrocarbons in the Qum area which as a famous area of blow up of the oil in 1956. The million or hundreds of joints in the salt are related to the tectonic forces in the regional scales (Talbot&Aftabi, 2004).These joints also seen in the bed rock of several salt domes like Qum Kuh-Dashti, Gachin and Pohl.
   Potash lenses founded at Pohl, Larak and Hormuz Island are folded and jointed as salt matrix. With changes in the rates (rise-erosion) the amount of potash lenses changes in dead or alive domes.
   The Mangarak fault zones was a lineament built into the Pan African basement and that reactivation of this lineament controlled the deposition of the cover sequence since Infra-Cambrian times and is even now acting as an active transfer strike slip fault in the Zagros.These lines decorated by a series of salt domes in the location of pull apart or pushed up structures. Some of the salt structures in the Zagros area inverted from push to pull and opposite in different times .The processes of change in the rate of compression from the Arabia recorded by erosion and sand deposits in the decorated salt domes in the Persian Gulf and suggest change of the tectonic system from compression to extension and opposite in a compressional zone or fold and thrust belt. Also field studies and analogue models suggest intrusion of older salt into youngest (in source) during the inversions. No one knows about the push up or pull apart in the regions with two horizons(or three) of salt like Central Iran and changes of these two systems together .The possibility of two salt horizons in the mother salt is considered very important for the migration of hydrocarbons and other fluids thought the structures in the Zagros.
   These dead and alive salt domes and their related anticlines in the Zagros are related to the twins of pull apart in opposite dead or alive of the salt structures decorated them. The rate of extrusion and erosion change the external shape of a diaper from alive real fountain to dead droplets. Other Pseudo-fountains and Pseudo-droplets are related to the collars.

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