Writers : BabakiA & Aftabi.A. J
Refference : Geosciences Scientific Quarterly Journal,No.:61,P.:40
Publishing Year : 1385

Abstract :
The Gole Gohar iron deposit is located at about 55 km southwest of Sirjan and in the eastern edge of the Sanandaj Sirjan structural zone of Iran. The host rocks of the ore deposit include metamorphosed sedimentary-volcanic rocks of the greenschist facies, probably of Upper Proterozoic-Lower Paleozoic age. The most important host rock units include shale, sandstone, gabbroic-basaltic and diabasic sills, diamictite and cherty carbonatic sequences that have been changed to thick carbonate successions in the upper units. The structure of iron ore comprises macro, meso and microbanding of magnetite associated with shale, sandstone and cherty carbonates. The presence of diamictites and phenoclasts in magnetite banding and host rocks indicates an iron ore association similar to the Rapitan banded iron ore. Magnetite banding, granular, banded and massive textures all represent deposition of iron as hydromagnetite. The presence of organic matter (graphite) and microlayers of pyrite indicates variation due to reducing-oxidizing conditions controlled by oxygen fugacity at the time of formation of the iron ore. The sills of basic rocks in the region are of tholeiitic basalt characteristics that represent the process of inactive oceanic rifts at the time of ore formation. The presence of diamictites and dropstones represents glacio-marine deposition associated with volcanic-exhalative activity. The recharge of seawater into rifting basin reacts with basic intrusives, old metamorphic iron bearing rocks and old banded iron ores, causes leaching and discharging of iron and silica, producing exhalative hydrothermal fluids. The upflow discharge of hydrothermal solutions into the seawater and sedimentary basin, followed by reaction with cold glacial water, causes hydromagnetite deposition within sediments and diamictites. The presence of massive magnetite texture, abundant tourmaline and low content of manganese indicates proximal ore mineralization in the central part of the volcanic sedimentary activities formed at about 100-250°C.
Subject List : Mineralization