Abstract
Manganese mineralization associated with phyllites in and around Joda, Odisha belongs to the Iron Ore Group of Noamundi basin and is a part of Jamda-Koira belt of East Indian Shield. The present study area comprises low to medium grade tectonites containing economic resources of both iron and manganese. Present study is concentrated on Manganese mineralization. Field study and petro-mineralogical observations reveal syngenetic character of manganese ores comprising lowT higher oxides viz. pyrolusite, cryptomelane, manganite as major Mn-minerals along with highT lower oxides viz. jacobsite, bixbyite, braunite and hausmannite as minor Mn-minerals. The Mn-ore bodies and associated phyllites have undergone multiple phases of deformation and metamorphism followed by hydrothermal and supergene processes. Four deformational phases have been deciphered during field study. Geochemical analyses of ores and phyllitic host rocks show high values of Al2O3, TiO2, Ba, Co, Ni, Cr, Cu, Sc, V, As, Zn but depletion of Sr, Yb, Sm, Nb. Geochemical data infer ores to be a recycling product originally derived from a mafic crustal source of tholeiitic character. Age data obtained from Sm-Nd ratio of two rock samples are 3.46 Ga and 2.79 Ga. Present work provides a critical assessment on the multiphase mineralization of manganese ores.
Highlights
The present study area, in and around Joda, comprises the Precambrian Iron Ore Group (IOG) of the Noamundi Basin, Odisha, a part of the Mesoarchean greenstone belt (3.5-3.0 Ga) viz. Jamda-Koira belt of the East Indian Shield (EIS)
In addition to megascopic and petrographic analyses, the major, trace and rare earth element geochemistry of the manganese ore and associated phyllitic host rocks of the present area confirm the chemistry of the samples as well as the composition of the source material indicative towards a parent magma of basic affinity
The manganese ore bearing Banded Iron Formation (BIF) deposits in a greenstone belt with evidence of volcaniclastic association postulate that BIF hosted manganese-iron ores in and around Joda are akin to Algoma character rather than Lake Superior type
Summary
The present study area, in and around Joda, comprises the Precambrian Iron Ore Group (IOG) of the Noamundi Basin, Odisha, a part of the Mesoarchean greenstone belt (3.5-3.0 Ga) viz. Jamda-Koira belt of the East Indian Shield (EIS). Low to medium grade tectonites containing economic resources of both iron and manganese are themajor rock types of the regional Noamundi synclinorium. Manganese ores, in this area (lat: 21°46’ - 22°10’N; long: 85°06’ - 85°35’ E) are hosted mainly by tuffaceous phyllites of the IOG (3.3-3.1 Ga, Saha et al.1988) in the eastern limb of the Noamundi synclinorium, whereas iron ores are associated with mainly quartzites and phyllites in some places. Manganese mineralization in the Joda-Noamundi sector reveals recycling of manganese through different phases of tectonic deformation and metamorphism followed by later hydrothermal and supergene processes
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