Mineralogy, geochemistry and genesis of Temelieh Manganese ore Deposit (NorthWest of Selseleh, Lorestan Province)

Temelieh area is located about 20 Km northwest of Selseleh (Lorestan Province). Geologically, the area is a small part of the Harsin radiolarite complex. Petrography consists of radiolarite, peridotite, gabbro, plate dikes, basalt and andesite, limestone, and marble. Manganese mineralization occurs as vein-veinlet and is mainly formed in faults, joints, and fractures that crosscut in radiolarites. Based on mineralogical studies, the manganese paragenesis is composed of pyrolusite, psilomelane, todorokite, cryptomelane, lepidocrocite, and manganese oxide-hydroxide (housmanite, hydrohousmanite, Manganite). The essential waste minerals are calcite and quartz. Based on geochemical data from major and trace elements, using different distinguishing charts and elemental ratios, there is a good relation between the manganese-rich region and the hydrothermal deposits. On the other hand, calculation of element designated ratios like Mn/Fe )mean 0.92), Ti/Al (mean 0.01), Co/Ni (mean 0.97), Co/Zn (mean 0.28), U/Th (mean 0.73), La/Ce (mean 0.32), LREE/HREE (mean 8.64) and ΣREE (mean 56.53) indicate Temelieh manganese ore is hydrothermal. Comparison of the REE normalized pattern of Temlieh manganese ore with other manganese deposits in the world indicates the hydrothermal origin of this deposit. REE distribution pattern indicates Ce positive anomaly with mean 24.5 and Eu negative anomaly with mean 0.54 that is compatible with hydrothermal manganese deposit. Accordingly, ore-forming fluids could be originated from meteoritic or magmatic water circulating through volcanic rocks, dissolve manganese and other metals and, while rising from suitable areas, deposits them in along the fault planes and fractures.