Abstract
In this paper, we described the petrographical characters of the Mn-bearing rock types outcropping in the Kalakhuta, Ghatia, Gararia, Itala, Wagaicha, Tambesara and Talwara villages of Banswara district. The Mn associated rocks in the study area are phyllite, schist, quartzite and limestone. The mineral assemblage in phyllite formed under greenschist facies metamorphism. Petrographic studies of various phyllite samples also reveal that porphyroblasts of biotite sat in the fine-grained micaceous matrix (Biotite, muscovite, chlorite) along with quartz, opaque and ore minerals. Petrographic studies of schist reveal its formation under prograde metamorphism. Mineral assemblages observed in schist are typical of greenschist to lower amphibolite facies. The various schist samples at places show clusters made up of perfect rhombshaped garnets which suggest the increase in the grade of metamorphism. The quartzites are disposed conformably with the phyllites, and are at times brecciated and re-cemented by secondary chert and manganese. These Mn-bearing quartzites are with sutured/serrated and straight grain boundaries. The quartzite samples are fully composed of quartz showing undulose extinction with subordinate feldspar, micas and carbonatic materials. The petrographic characteristics explain that mostly limestones are the dolomitic composition but some ferruginous varieties are also noticed at places. The purer variety of limestone consists of calcite, dolomite and some magnetite but tremolite, quartz and some minute flakes of biotite also occur in impure variety.
Highlights
Banswara district is situated in the southern-most part of Rajasthan
We described the petrographical characters of the Mn-bearing rock types outcropping in the Kalakhuta, Ghatia, Gararia, Itala, Wagaicha, Tambesara and Talwara villages of Banswara district
The various schist samples at places show clusters made up of perfect rhombshaped garnets which suggest the increase in the grade of metamorphism
Summary
Banswara district is situated in the southern-most part of Rajasthan. The area is very much renowned by its Bhukia gold deposits. No systematic approach to study the Mn-bearing rocks of Banswara manganese ores belt has been made in an attempt. In this communication we are describing the first detailed petrographic and X-ray diffraction studies of rocks associated with Banswara manganese ores belt, with an aim to understand petrofacies of the study area. The petrographic study is a vital tool for providing detailed and relevant information over mineralogy, metamorphism, alteration and paragenetic history of rocks to understand its origin. These details may be helpful for future studies in the study area to resolve palaeoclimate, geo-tectonic setting and depositional environment
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