How Observations of the Salt Plugs in the Iranian Fars Province and Analog Modeling Reveals Salt Tectonic Evolution: Application to the Understanding of Middle East Settings and to Kinematic Restoration

Abstract

The Fars province in Iran and its adjacent offshore part exhibit a wide variety of salt plugs. More than 40 can be observed on the field today. The aim of the presentation is to show the different types of diapirs. Though the salt was deposited during the Precambrian Hormuz episode, geological evidence both from field work and from seismic interpretation shows that the movements have started as early as Paleozoic, then climaxed the Late Cretaceous and then Cenozoic evolution of the Iranian/Arabian plate collisions. After a brief outline of salt diapirism in the Fars province, we will illustrate the buried salt domes in the offshore region, where the Zagros shortening is not yet active. The patterns there illustrate what might have been the state of the Fars province prior to the collision, with a mini basin pattern of salt domes evenly spaced where salt thickness is not varying rapidly. Then we will illustrate the relationships between salt plugs, folding and faulting with several regional cross sections radially crossing the Fars domain. Analogue modeling with silica/silicon settings under X ray scanner have been set up to try to replicate the geological evolution that has been observed. These analogue experiments show the role the thickness of detachment layer, pre-existing salt diapir and salt ridge on localization of folds, rotation of fold axes and creation of tear faults. In some experiments, different sizes of salt diapirs were set up, then shortening occurred. The influence of sediment thickness on top of the salt and of varying rate of shortening can also be estimated. This allowed to discuss the scaling of the experiments to correctly represent the geological world in such experiments. Geological field observations and analog modeling provide thus clues to validate backward kinematic restorations, and to confidently extrapolate such methods to other settings where salt tectonic is active.

AAPG Datapages/Search and Discovery Article #90362 ©2019 AAPG Middle East Region, Geosciences Technology Workshop, 2nd Edition Structural Styles of the Middle East, Muscat, Oman, December 9-11, 2019