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Abstract
The Magnetite-Quartzites of Tirthamalai form a part of the large iron ore belt which occurs in the Precambrian high grade granulite terrain of Tamilnadu. In the present study an attempt is madeto understand the ferride group of elements and their significance in the origin of Banded Magnetite-Quartzite (BMQ) of the study area. They are associated with pyroxene granulites and hornblende biotite-gneisses. About 20 magnetite-quartzite samples were collected and analyzed for the ferride group of elements (FGE) like Mn, Ni, Ti, Co, Cr, and V. The results of geochemical analyses show FGE very much lesser in the magnetite -Quartzite than in pyroxene granulites.The proportions of Mn and Ti are enriched compared to other elements. The FGE depleted concentrations in the magnetite-quartzite of the study area indicate that thesource materials might have been derived from weathering of landmasses and not from any volcanic sources. Also, the FGE studies clearly show their similarities with other well-known metasedimentary iron ores. The results, strongly suggested that the magnetite-quartzite and associated pyroxene granulites of Tirthamalai region are of different modes of origin, namely meta-sedimentary and meta-volcanic respectively.
Keywords: Banded Magnetite-quartzite, Ferride Group Elements (FGE) and Tirthamalai region, India
1. Introduction
Worldwide, the iron ore deposits are closely associated with schist belts, gneisses and granulite terrain of Archean age. FGE plays a vital role in the origin of Banded Magnetite- Quartzite (BMQ) in Tirthamalai area, Dharmapuri District of Tamil Nadu, India. The iron formations of Tamil Nadu state occur as bands, enclaves, veins in the districts of Salem, Dharmapuri and Tiruchirappalli (King and Foote, 1864; Holland, 1893; Dubey and Karunakaran, 1943; Krishnan and Aiyengar 1944; Ramanathan, 1956; Saravanan, 1969; and Radhakrishna et al., 1986; Rajendran, 1996; Rajendran and Chandrasekaran, 2000; Rajendran et al., 2007, Thirunavukkarasu, 2009). These are banded magnetitequartzite differentiated on the basis of presence of magnetite and quartz and having an iron content of 3540% (low-grade iron ores; Radhakrishna et al., 1986). The Iron ore deposits are in the age group of Precambrian iron formations occurring as narrow, highly deformed and metamorphosed belts within the Archaean granulite terrain (Prasad et al., 1982). These rocks are older than 3,000 Ma (Radhakrishna et al., 1983).The BMQ deposits of Thirthamalai in Dharmapuri district have shown that these iron formations consist of...