PETROGRAPHY, MINERALOGY AND GEOCHEMISTRY STUDY OF SANAM MOUNTAIN SOUTHERN IRAQ

Abstract

Jabal Sanam) Hump Mountain) forms a prominent isolated geomorphic and geologic feature in Iraq. The rocks constituting the Sanam Structure belong to the Infracambrian, possibly an equivalent of the Hormuz Salt Series of the Arabian Gulf region; the rocks of Jabal Sanam consists of four unites are from top to bottom brecciated limestone, gypsum and dolostone which indicated may be subjected to multiple redeposition also affected by dynamic metamorphism with a noticeable amount of ironstone could be categorized in to two major groups: Precambrian iron formations these rocks could be divided in to two subgroups: Algoma type it represents the oldest Precambrian type of iron formation stones which ranges in age from (1800-2600 M.Y.) ago, and Superior type: this type assemblage is commonly associated with clastic sediments in shields and miogeosyncline zones like quartz claystones. Phanerozoic ironstone This ironstone found as oolitic hematite beds having about 8m thickness was replaced partially or completely by hematite. Therefore, it could be suggested that these Iron rich sediments firstly deposited in shallow lagoonal environment side by side with evaporite and carbonates rocks forming Hormuz salt series during Precambrian period. Later, these ironstones and the some basement rocks were influenced by faulting, deformation and hydrothermal solutions through the processes of evolution of Jabal Sanam salt structure where it could be also suggested that topographic relief drove circulation of surface derived waters through the fault system at that time. Thus, the actions of thermal ground solutions transported Fe-ions, then re-precipitated it later within the different forms of rocks in Jabal Sanam as veins or thin beds or inter sediments materials through many stages of geological history like many cases of salt domes rocks globally.