**3. Geology of the study area**

The study area is under laid by the rock formations ranging from Archaean to Permo-carboniferous age (**Table 1**). The rock formations include quartz-mica-schist, banded-biotite-hornblende-gneiss/granite, and coarse-grained sandstone (**Figure 2**). Major part of the study area is occupied by quartz-mica-schist. The second dominant rocks in the study area are biotite-hornblende granitic/gneisses with migmatite and pegmatite patches, which are observed from the northern part of the study area. A small portion in the eastern and southern parts is covered by coarse-grained sandstones [11]. A very small area in the eastern part is occupied by gabbro. Mineralogically, quartz-mica-schist is composed principally of quartz and mica, and generally of muscovite and biotite. The modal composition of quartz-mica schist shows 25% of muscovite, 15% biotite, 30% orthoclase, 20% quartz, and 10% plagioclase and chlorite, together with some opaque minerals [12]. The biotite-hornblende granitic/gneisses appear in their light and dark color banded texture. The light color band is composed of quartz and plagioclase feldspar, while the dark color is composed of biotite, hornblende, and opaque's. The modal composition of biotite-hornblende granitic/gneisses have 34.25% of quartz, >3.75% k-feldspar, 20.35% of plagioclase, 35% of biotite,


#### **Table 1.**

*Geological succession of the study area [10].*

**Figure 2.** *Geological Map of Study area.*

5.2% hornblende, 0.5% chlorite,0.15% of sphene, 0.15% of zircon, 0.3% of epidote and 0.10% fluorite and 0.4% opaques [13]. Since the coarse-grained sandstones of Gondwana age are considered to be the weathered product of Eastern Dharwar Craton, it is essentially composed of quartz and little proportion of feldspars, together with accessories of biotite, hornblende, apatite, epidote, fluorite, sphene, zircon, etc. The volume percentage of the different minerals depends on the cementing material and environment of deposition. The muscovite and biotite micas, fluorite minerals contribute to the higher F levels in this study.
