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Geochemistry and Genesis of Manganese Ore Deposits, Andhra Pradesh, India

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Geochemistry and Genesis of Manganese Ore Deposits, Andhra Pradesh, India International Journal of Engineering Trends and Technology ( IJETT ) - Volume 66 Number 3 - December 2018 Geochemistry and Genesis of Manganese Ore Deposits, Andhra Pradesh, India T.Suryanarayana1,2 Professor& Geology&Wollo University 1Department of Geology, College of Science and Technology, Andhra University, Vizag 530013, India. 2Department of Geology, College of Natural Science, Wollo University, Dessie Campus, Ethiopia. Abstract after Kodur village iscomposed of quartz, feldapar, Manganese deposits of Vizianagaram district, manganese pyroxenes,Spandite garnet and apatite. Andhra Pradesh occur as conformable bands in the Fermor (1909)Ascribed theOrigin of the manganese Khondalite Group of rocks of Eastern Ghats complex. ores of this region to the alterationof these manganese The dominant manganese ore minerals include rich rocks. Later workers in this area, Krishna Rao cryptomelane, psilomelane, pyrolusite, hausmannite, (1954,1960), Raghava Rao and srirama Rao(1955), bixbyite and wad etc., Quartz, orthoclase, garnet, Mahadevan and Krishna Rao (1956) agreed on kaolinite, hematite and mica are the associated gangue theEssentially hybrid nature of the kodurites due to minerals. Presence of high silica and dominance of theAssimilation of manganeferous sediments by CaO over MgO, K₂ O over Na₂ O, Ni over CO, Zn and graniticIntrusions. They also attributed the origin of Cu over Pb are the elemental characteristics of the theseManganese deposits to the metamorphism of the deposit. Discrete apatite grains are identified in quartz originallyBedded manganeferous sediments. and orthoclase. Continental weathering appears to be As these oredeposits are academically andeconomically the source for manganese and iron. After deposition important, it is proposed here to carrying out detailed and diagenesis, the manganese rich sediments were studies on manganese ores of metamorphosed under granulite facies (max.700˚C and Garbham,Sadanandapuram and Kondakinguva areas min. 6 kb pressure) conditions and subsequent ofVizianagaram district in respect to of these ores. deformation and supergene enrichment produced the Geological Settings: present deposit. The manganese ores are generally of The general geology of the area has been describedin low grade with high phosphorus content. detail by most of the previous workers (Fermor, 1909,PrabakaraRao 1950 and Krishna Rao 1954) and Keywords - Manganese, Kodurite, Eastern Ghats, only a brief and relevant reference is given here.The Phosphorous, Geochemistry, Genesis. manganese ore deposits of the study area are associated with Meta sedimentary rocks of the khondalite series of I. INTRODUCTION Precambrian Eastern Ghats group of rocks. The members of khondalite series are garnet and sillimanite Andhra Pradesh contributes about 9% of the total para gneisses andschist’s, garnetiferous quartzitesand Production of manganese ore in the country. intercalated calc- silicate gneisses and marbles. There ManganeseDeposits in and around Kodur in are several mines and pits scattered mainly in the two Vizianagaram district,Andhra Pradesh, are among the neighboring villages, Koduru and Garbham, which lie oldest working mines inIndia. The manganese ore at a distance of 5 and 20 kilometers respectively from deposits of this area are thus adistinct type according to Garividi railway station on Madras- Kolkata railway Fermor and the mother rock ofthese manganese ore route. (Fig: 1 a & 1 b). deposits is what he termed“Kodurite”. Kodurite, named ISSN: 2231 – 5381 http://www.ijettjournal.org Page 170 International Journal of Engineering Trends and Technology ( IJETT ) - Volume 66 Number 3 - December 2018 The manganese ores in and around Garividi, Koduru forming hillocks in the N –W and S- W parts of the area and Sadanandapuram area are called Kodurites. The and the calc- granulitesoccupy central part of the area. rock types associated with Kodurites are namely The bedded manganese ore occurs conformably khondalites, quartzites, granite gneisses and patches of underlying the calc- granulites. A number of quarries calc- granulites.The khondalites are very prominent and are worked for manganese at places like Garividi, are cut by minor pegmatite bodies at places. Quartzites Sadanandapuram and Koduru areas in the Kodurite belt are also abundantly present in these kodurites and (Fig: 2&3). ISSN: 2231 – 5381 http://www.ijettjournal.org Page 171 International Journal of Engineering Trends and Technology ( IJETT ) - Volume 66 Number 3 - December 2018 Garbham area is characterized by the rock types manganese ore occurrences have been reported in mainly of quartzites, granite gneisses, Khondalites and Kondakinguva area near Salur (NageswaraRao 2014). patches of calc- granulites. The manganese ore In all these areas, ore occurs at shallow depths (2-3 generally occurs in the bedded from and can be treated Mts)and continued up to the maximum of 20 Mts(Fig: 4 along with the calc- granulite bands. Recently a & 4 b). Careful observation of the manganese quarries and the unconformable relationbetween the ore and the wall adjoining areas in the manganese belts reveals that the rock was observed where the supergene ore migrated ore deposit is associated with rock units namely along the foliation and joint planes of the paragneisses garnetiferousquartzites and calc- granulites. The former and now present in an apparent discordant relation. The dominated in the Garbham area and the later in the dimentions of each ore band are several hundreds of Koduru area. However, the manganese ore has a meters length and approximately 5 meters width. The definite stratigraphic position in the sequence of manganese beds are of varying continous of thicknesses deposition of khondalite suite of rocks. It can be stated ranging from less than a meter to four or five meters that calc- granulite association with manganese ore is and contain primary mineral assemblages and their observable in all the places, even as minor, thin bands. supergene alteration products. Krishna Rao (1960) The ore bands have a trend of NW-SE to E-W. considered the manganeses bearing sediment to be the According to Mahadevan and Krishna Rao (1956) the oldest member in the PrecambrainKhondalite series. manganese ores at Koduru are part and parcel of the Calc- silicate rocks occur in immediate contact with Khondalite suite of metamorphosed sedimentary rock, manganese beds in the Kodur group deposits, where the ore bands and lodes being conformable with asquartzites, and in places with K-Ba feldspars and members of khondalite series. The primary manganese garnets, occur as wall rocks at Garbham. The Calc- ores are certainly conformable with respect to the silicate rocks consist of quartz, K- feldspar, enclosing rocks of the khondalite series. The primary calcite,scapolite and diopside. layering of the ores was also conspicuous. The only ISSN: 2231 – 5381 http://www.ijettjournal.org Page 172 International Journal of Engineering Trends and Technology ( IJETT ) - Volume 66 Number 3 - December 2018 II. MINERALOGY OF THE ORES Brauniteis identified in a few samples in minor quantity and is replaced by cryptomelane. It is euhedral to Mineralogy of the manganese ores have been studied subhedral and present in the Garbham and from a suite of samples systematically collected from Sadanandapuram areas. The jacobsites, which are the mines at Garbham, Sadanandapuram and present both as individual free grains andalso in Kondakinguva areas. Manganese minerals intergrowth with pyrolusite. Cryptomelane forms identification was based on ore microscopic study and colloform bands with or without pyrolusite. It replace supported by XRD in a few cases. The present study Jacobsite as well as silicate gangue minerals. Pyrolusite revealed the presence of braunite, Jacobsite, pyrolusite, occurs as veins cross cutting the colloform bands. cryptomelane, as also graphite, hematite and traces of Pyrolusite replaces many manganese minerals (Fig:5& pyrite. The gangue minerals are quartz, orthoclase, 6). garnet, kaolinite with minor amounts of biotite and muscovite. ISSN: 2231 – 5381 http://www.ijettjournal.org Page 173 International Journal of Engineering Trends and Technology ( IJETT ) - Volume 66 Number 3 - December 2018 Jacobsite is granular, subhedral to tabular and isolated Garbham to Sadanandapuram and to Kondakinguva grains enclosed by secondry minerals in places. Islands areas. Replacement of these silicate minerals along ofsilicate minerals are found in Jacobsite. Hausmannite grain boundaries and in intergranular spaces by is found as exsolutionlamelle in Jacobsite and is manganese ore minerals are very commom (Fig: 7). essentially a primary mineral formed under high grade Kaolinite patches formed by alteration of orthoclase are metamorphism. distinct at a number of places in the manganese ore. Quartz, orthoclase, garnet , Kaolinite and minor Garnet occurs as subhedral to anhedral grains along amounts of biotite, muscovite from the silicate gangue with quartz and orthoclase. minerals. The silicates quantity increases from III. PARAGENESIS Based on textural relationships of various minerals, a paragenitic table (Table 1) mainly for oxides is given below. Table 1: Paragenetic Table for oxide minerals ←-----------Time---------→ Primary Secondary Bixbyite ----- Braunite ----- Hausmannite ----- Jacobsite ----- Vredenbrgite ----- Psilomelane ----- ----- ----- Goethite ----- ----- ----- ISSN: 2231 – 5381 http://www.ijettjournal.org Page 174 International Journal of Engineering Trends and Technology ( IJETT ) - Volume
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