Mechanical Modeling of Diapirism in the Zagros Simply Folded Zone

Mehrdad Madani Kivi*, Gernold Zulauf, and Carlo Dietl
Johann Wolfgang Goethe, Frankfurt University, Germany
*[email protected]

The objectives of this presentation are to discuss: (1) the cause for the distribution of the latest Proterozoic-Early Cambrian Hormuz Salt Series in the Zagros Province, (2) the timing of salt diapirism, (3) the influence of compressional strain on the early flow of salt, and (4) the location of the salt diapirs relative to structural elements. The current tectonic activity in the Zagros fold-thrust belt is the consequence of continental convergence between the Arabian and Eurasian plates since the Late Cretaceous. The Zagros fold-thrust belt is a key region for studying the early processes that occur in convergence zones. The tectonic evolution of the Zagros fold-thrust belt is complicated by the occurrence of a Phanerozoic sedimentary cover, which is partially decoupled from its underlying basement, above a mechanically weak layer of Hormuz salt and anhydrite. Additionally, a Proterozoic sedimentary section (known in Oman) most probably occurs below the Hormuz basal detachment in some parts of the Zagros Province. Following the deposition of the Hormuz Series, a long period of remarkable tectonic calm lasted from the Paleozoic to middle Cretaceous times. We used analogue modeling to study: (1) the mechanisms of salt diapirism, and (2) the role of pure constriction strain on the overburden and extrusive salt. Based on the study of ETM satellite images and geological observations, we carried-out analogue sand-box experiments using several non-linear viscous plasticines that were imaged using Computed Tomography scans to distinguish the salt structures. Our results suggest a considerable influence of the strain rate on the geometry of the deformed folding and overburden. We will show how salt flows from the deformation of the overburden, before diapirs are exposed in the core of the anticlines and along faults. Understanding the formation and development of the Hormuz diapirs is a very important issue, both for reservoir prediction and hydrocarbon trapping in the Zagros Province.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain