STUDIES ON THE STRUCTORE, PETROLOGY AND CHROMITE DEPOSITS OF PAUNl - BHIWAPUR AREA, MAHARASHTRA

Abstract

The present work includes a scientific study of the structure, petrology and the chromlte deposits of the Pauni-Bhivapur area comprised largely of the Pre-Cambrian rocks of the Sakoli series. Interrelations of different rock units of the area, covering over 160 sq.kra. and their stratigraphic sequence have been established on the basis of detailed geological and structural mapping. The lithology and general disposi tion of the various formations have been worked out. A brief discussion on the regional stratigraohy of the Sakoli rocks has boen included with a view to facilitate correlation. Field data of different structural elements were used for the geometrical analysis of fold systems, with the help of selective and synoptic fl and J3> diagrams. This, in turn, has made it possible to infer the tectonic history of the area. Qualitative and quantitative petromineralogic studies of different rock units consisting of igneous,metamorohic and sedimentary types have been carried out and their petrography is discussed in detail. The data obtained from the mechanical analyses of sandstones of the younger sedimentaries as well as of their heavy mineral content have been used for the study of environmental conditions of deoosition. The genetic aspects of the various rock tyVes, particularly the amphibolites, the granites and pegmatites and the iron ores have been deciphered from their field relations, mineral paragenesis and their grade of metamorphism. A brief review of the various ideas on the genesis of granites is presented. The distribution, shape and size of the Pauni ultrabasics have been studied. The petrographic studies of various mineral assemblages (ii) / comprising the ultrabasics havebeen carried out. The different stages of hydrothermal changes suffered by these rocks have been discussed. A review on genesis of different types of ultrabasics is also given followed by a discussion on the origin of the Pauni ultrabasics. The localisation of the chromite deposits, their structure,shape, size and types have been studied. An examination of several thin and polished sections, has revealed their texture, optical characters, and mineral associations. The major and trace-elements of 13 purified chromite samoles of the area were determined by chemical and spectrographs analyses respectively. The interrelationship of various elements in the chromites and their variations have been established. A review of the chemistry of chromite is given in some detail. The genesis of the Pauni chromites has been discerned from their field features and megas copic and microscopic characters. Mining methods applied for the exploitation of the chromite deposits have been examined. Various methods of prospecting and exploration for chromite deposits in general and their suitability in the present area have also been discussed. Further, a brief dis cussion on the beneficiation^production, reserves, grade, utilization and future orospects of the chromite deposits is given . Conclusions based on t'->e above studies have been summarised in the last chapter.