The Emergent Hormuz Salt Plugs of Southern Iran

The extrusive salt plugs in the “gently folded zone”of the Zagros mountain belt are almost exclusively composed of Hormuz evaporites carrying exotic blocks, originating at depth of 3–5 km below surface, dated as mainly late Precambrian. In recent years, there have been considerable advances in the understanding of the history of emplacement, on the stratigraphy of the very large exotic blocks of bedded Infra‐Cambrian sediments, on the stratigraphy of the very large exotic blocks of bedded Infra‐ Cambrian sediments on the entrained volcanic and intrusive igneous rocks and on the mineral occurrences. The charactreistic and controversial feature are described, with the minearl occurrences. The characteristic and controversial fetures are described, with emphasis on the newer information and on the relationships of the plugs to normal folds, thrusts and transverrse fracture zones. The absences at surface of the many cubic kms of country rock displaced from the neck of each plug has hitheto presented an unsoloved probelm; prevoious explanation fail to fit availabel facts. It is now postulated that in most cases initial extrusion took place at higher stratigraphic levels, and that the original vent material has been eroded along with the sediments lost following uplift of the mountain belt. The concept that pre‐orogenic plug movement was not exceptinal but normal, so that the plugs penetrated an essentially flat‐lying sedimentary blanket, resolves also the contrast between their regular distribution in the southeastern Zagros and their random reltion to the Pliocene fold trends, as well as the tendency for inflexions of fold axes to be located where they encounter the weak points provided by the salt intrusions.