The geological , mineralogical and petrological studies of holenarsipura schistbelt, southern india

The geological , mineralogical and petrological studies of holenarsipura schistbelt, southern india

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  YUVARAJA COLLEGE (An AutonomousConstituent college) Department of Earth Science and Resource Management Project report on THE GEOLOGICAL , MINERALOGICAL AND PETROLOGICAL STUDIES OF HOLENARSIPURA SCHISTBELT, SOUTHERN INDIA.
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  A Project reportsubmitted by PRAMODA G YB120112 (Final year B.Sc student (CBEr)), Yuvaraja’s college, Mysuru Under guidance of Dr. M. P. Dharmesh Lecturer, Dept of Earth Science and Resource Management Yuvaraja’s college, Mysuru
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  GEOLOGICAL FILED WORK Geologyis a field science. Without sustained filed work, no theoretical aspect of geology can be taught and no geological and mineral exploration or research can be carried out. Fieldwork is an important part of Geology as it provides many of the data on which our knowledge of the Earth and its evolution along with that of life through time.
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  GEOLOGICAL HISTORY OFKARNATAKA The geological history of Karnataka is confined two oldest eras that is Archean and Proterozoic. Major part of state consists of Archean rocks. A substantial part of north Karnataka is covered by Decan trap, representing of phenomenal outburst of volcanic activity at the dawn of Cenozoic era. The oldest rocks dated so far in Karnataka are a group of grey gneisses giving and age ranging from 3400 – 3000 million years. Since these gneisses contain enclaves of deformed and metamorphosed amphibolitic and granulitic grade rocks, the existence of an older group of sediments and associated igneous intrusive
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  GEOLOGY FIELD CARRIEDAROUND YENNEHOLERANGA-BETTA The Holenarasipur greenstone belt of southern India is well known for a variety of mineral deposits such as chromite, asbestos, magnesite, corundum, Kyanite, Staurolite,Beryl, feldspar, muscovite, quartz, graphite and iron ore, so it is called as “Natural mineralogical museum of Karnataka” and it is also known as “Veritable geological museum’, “Petrological paradise” it is titled so because this region is known for ‘nine metamorphic minerals.
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  GEOLOGY The contact betweenthe Bababudan and the Sargur Groups of rocks can be seen in the Holenarasipur belt. The northern part of the belt, lying to the north of the Hemavathi River, is classified as Bababudan Group while the southern N-S striking limb, lying to the south of the River, is classified as part of the Sargur Group. The southern N-S striking 20 km long limb of the belt is made up of an association of ultramafic-mafic and meta-sedimentary rocks.
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  • The rocksstrikes N-S and dips 45°-70° east. Holenarasipura schist belt is Trident in shape. • The belt extends maximum length of 65KM from Doddagudda to Yedegondahalli with a wide range of 0.5KM to 3KM and belt covers an area of 250Sq.Km in which Yenneholerangana Betta is a small hillock which is named after the God Rangaswamy. •The southern terrain is high grade metamorphic terrain, northern part is metamorphosed.
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  Amphibolite Sample •The Amphibolitesoccurs as linear bands occupying the hill top and most part of the hill. The dip and strike of the amphibolites are measure with the help of clinometer whose dip east 31 W strike is N6E-S84W. •Minerlogically it is made up of green hornblende and grey plagioclase minerals aligned parallel to the plane of schistosity. •These amphibolites belong to Sargur group and these forms a part of intrusive ultramafic complexes
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  CHLORITE SCHIST: •It isa low grade metamorphic rock. It exhibits well developed schistose texture, the grains are aligned parallel to the schistose. It is a green colour with distinct cleavage and low hardness. •It occurs in the form of linear and thin linear lenses occupying the lower flanks of Yenneholerangana Betta. This linear and parallel bands show variable dips, their trend in NNE-SSE and are soft meta-sedimentary rocks. They have been subjected to low grade green schist metamorphism. Along with Chlorine, Granetiferrous chlorite-schist are seen and collected small grain of Garnet are seen whose size is0.2cm and less that
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  GARNET •In the studyarea the garnet clearly shows Cubic or Dodecahedron shape and cleavage is perfect. •Luster is vitreous in nature. •Some of the weathering rocks have been observed in the study area. CALCITE Calcite is a common formed of sedimentary rocks, limestone in particular, much of which is formed from the shells of dead marine organisms. Approximately 10% of sedimentary rock is limestone. Calcite is the primary mineral in metamorphic marble.
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  ASBESTOS Asbestos is oneof the important economical mineral along with carbonates which are derived form the Serpentine bodies in the form of Calcite. It has Rhombohedral cleavage which is distinct in the crystals and exhibits low hardness i.e. it can be easily scratched by pen knife and it exhibits sub-vitreous luster. The asbestos are derived from the alteration of amphibolites these is low grade products which exhibits fibrous habit & fibers are long fine flexible and easily separable color variation from white to wooden brown the fibrous asbestos are found in between serpentine and trimolite actinolite schists these formed due to the metamorphism of ultra- amafic rocks.
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  STAUROLITE A special propertyof Staurolite is that often occurs twinned in a characteristic cross-shape called penetration similar to quartz, with the twinning displaying optical continuity. It can be identified in metamorphic rocks by its swish cheese appearance and often mantled porphoryblastic character to prism of 3-4cm long it exhibits dark brown to black color well developed crystals. Staurolite occurs in the form of anhedral crystals ranging from small crystals of Staurolites were collected.
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  KYANITE • Kyanite-Staurolite-Biotite- Muscovite schistare described as metaphillites. These metaphillites are easily weathered so they occupy low mound of undulated area. • These are exposed to surface in channel cutting area of NNE at Yenneholerangana Betta in filed it is seen that extensive invention of quartz veins in an important feature of this schist which helps to the concentration of bladed. •It exhibits varying hardness and cleavages. They are distinct and it exhibits vitreous to pearly luster. The samples were collected near channel cutting.
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  Talc-calcite rock isformed from Serpentine with subordinated Treolite, Actinolite, Anthophyllite, chlorite and Calcite. Along with this is a specimen is collected near the dyke such as formation is seen around the dyke such formations is seen around the dyke for several meters. It might have formed due to the hydrothermal alteration of feldspar to Mica.
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  VISIT TO ULTR-MAFICAND MAFIC REGION Ultra-mafic occupy a linear zone along the western margin of the schist belt. It occurs as numerous bands closely altering with chlorite schist, around Yenneholerangana Betta, particularly on northern flanks and towards east of the Yenneholleranaga Betta in Hemavathi canal sections. Some weathered Serpentines were seen in the valley region towards the east Yenneholleranaga Betta. It occurs as broadly lenticular bodies standing out as bold mass in the hills and as a resistant out crops in plain regions.
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  GRADE OF METAMORPHISM LOWGRADE MEDIUM GRADE HIGH GRADE   QUARTZ      FELDSPARS   MUSCOVITE         HORNBLENDE     PYROXENE CHLORITE       BIOTITE       GARNET   STAROLITE       KAYANITE     SILLIMANITE
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  The group memberswith mentor Dr. M P Dharmesh
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  Presented by Prmoda G Dept.Earth Science and Resource Management Yuvaraja’s College, Mysuru