Manganese Mineralization in Manganiferous Quartzite in the Boringpadar-Amath Area, Eastern Ghats Mobile Belt, Odisha, India: Implication for Climatic Changes

Abstract

The chapter brings to light an array of manganese mineralization with promising values, hosted in manganese ore and manganiferous quartzite and predicts the responsible climatic environment for the formation of manganese based on field observations, ore petrographic studies and geochemical inputs. Two bands of manganese ore and four bands of manganiferous quartzite are mapped to the southeast of Boringpadar and northeast of the Amath area belonging to the Eastern Ghats Mobile Belt, India. The manganese ores are represented by bluish-black to brownish-black, massive to foliated, metallic luster, nodular and botryoidal forms which are mainly bedded and fragmental types. The ore bodies are strata bound occurring in between calc-silicate granulite and garnetiferous quartzite which defines a characteristic stratigraphic horizon. Manganiferous quartzite is hard, white to black, highly jointed, fractured and brecciated which occurs at the contact of khondalite. Braunite, bixbyite, jacobsite, manganite, pyrolusite and todorokite are primary minerals that are associated with host rocks like quartzite and these minerals occur as inclusions and anhedral in shape. Secondary minerals are formed by the process of colloidal influx or metasomatism psilomelane-cryptomelane, pyrolusite and goethite are secondary minerals which occur in higher quantities. A relatively high temperature metamorphic jacobsite-bixbyite-braunite assemblage, low temperature hydrothermal pyrolusite-psilomelane-cryptomelane assemblage and supergene pyrolusite-manganite assemblage are recorded which were formed by recycling of manganese in different stages of mineralization. Replacement and relict textures are common between braunite-manganite-pyrolusite, jacobsite-braunite-pyrolusite and pyrolusite-psilomelane-cryptomelane-goethite. A geophysical investigation has also been carried out in the area to know the subsurface continuity of manganese mineralization. In Boringpadar, the apparent resistivity values vary from 10 to 240 ohm-m which displays low resistivity, and the apparent chargeability contour map shows high anomaly, indicative of a mineralized zone. In Amath, the apparent resistivity value varies from 20 to 140 ohm-m and the apparent chargeability contour map shows a high anomaly. The pseudo-depth sections were prepared over geophysical traverses to examine the subsurface distribution of apparent chargeability and apparent resistivity indicating mineralization prospects. This mineralized body starts almost from the surface and the contours of this anomaly zone open downward which is suggestive of the depth persistence of the causative source below 35 m. The analytical results of bedrock samples show high values of Mn, Fe, SiO₂, Al₂O₃, P, S and CaO. The values of Mn and Fe(T) ranged from 0.05 to 28.18 wt. % and 1.87–56.31 wt. %, respectively. In pitting/trenching samples, the Mn value ranges from 0.05 to 27.77 wt. % and the Fe(T) value ranges from 2.11 to 46.85 wt. %. The highest values of Mn come from manganese ore of the Amath area and maximum values of Fe(T) were recorded from manganese ore of the Boringpadar area. The above-mentioned data indicate that the manganese ores and manganiferous quartzite might be formed in the freshwater environment.