Geochemistry and Fuid-Inclusion Microthermometry of the Farsesh Barite Deposit, Iran
Journal Title: Geologos - Year 2014, Vol 20, Issue 3
Abstract
The Permian carbonate-hosted Farsesh barite deposit is located southeast of the City of Aligudarz in the province of Lorestan, Iran. Structurally, this deposit lies in the Zagros metallogenic belt and the Sanandaj-Sirjan Zone. Barite mineralisations occur as open-space filling veins, and as massive and replacement ores along fractures, faults and shear zones of the Permian carbonate host rocks. In order to determine the structure, in addition to petrographic and fluid-inclusions studies, an ICP-MS analysis was carried out in order to measure the major as well as the trace and rare earth elements. The Farsesh Barite deposit has a simple mineralogy, of which barite is the main mineral, followed by calcite, dolomite, quartz, and opaque minerals such as Fe-oxides. Replacement of barite by calcite is common and is more frequent than space-filling mineralisation. Sulphide minerals are minor and mainly consist of chalcopyrite and pyrite, which are altered by weathering to covellite, malachite and azurite. Petrographic analysis and micro-thermometry were carried out on the two-phase liquid/vapour inclusions in ellipsoidal or irregularly shaped minerals ranging in size from 5-10 m. The measurements were conducted on fluid inclusions during the heating and subsequent homogenisation in the liquid phase. The low homogenisation temperatures (200-125 0C) and low to moderate salinity (4.2-20 eq wt% NaCl) indicate that the barite had precipitated from hydrothermal basin water with low to moderate salinity. It appears from the major and trace elements that geochemical features such as Ba and Sr enrichment in the barite samples was accompanied by depletion of Pb, Zn, Hg, Cu and Sb. The geochemistry of the rRare earth elements,such as low ΣREE concentrations, LREE-enriched chondrite-normalised REE patterns, the negative Ce and positive Eu anomalies, the low Ce/La ratio and the positive La and Gd anomalies, suggest that the Farsesh barite was deposited from hydrothermally influenced sea water. The Farsesh deposit contains low-temperature hydrothermal barite. The scatter plots of the barite (close to sea water) in different areas on the CeN/SmN versus CeN/YbN diagram support the possibility that the barite was formed from seawater-bearing hydrothermal fluids.
Authors and Affiliations
Houshang Pourkaseb, Nazanin Zaheri, Abbas Chrachi, Alireza Zarasvandi, Hashem Bagheri
Keywords
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- EP ID EP166236
- DOI 10.2478/logos-2014-0015
- Views 178
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