Vidyashankar, H. V. and Govindaiah, S. (2009) Ore petrology of the V-Ti magnetite (lodestone) layers of the Kurihundi area of Sargur schist belt, Dharwar craton. Journal of the Geological Society of India, 74 (1). pp. 58-68. ISSN 0016-7622
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The V-Ti magnetite layers (lodestone) occur within the layered gabbro-anorthosites-ultramafic rocks emplaced into the migmatitic gneisses close to the high grade Archeaen Sargur supracrustal rocks in the Kurihundi area. The ore petrographic studies of the lodestone reveal the presence of primary Ti-magnetite, ilmenite, ulvospinel, pleonaste, hematite and pyrite, chalcopyrite, pyrrhotite and secondary Ti-maghemite, martite and goethite as well as secondary covellite. These layers contain Ti-magnetite (60%) and ilmenite (30%) with silicates (< 5%) exhibiting granular mosaic texture with well-defined triple junctions and are classified as adcumulus rocks. The grain-boundary relationships in the ores indicate considerable postcumulus growth and readjustment due to combined effects of sintering and adcumulus growth. Intergrowth textures (ulvospinel, ilmenite and pleonaste in Ti-magnetite and hematite in ilmenite) reflects exsolution features crystallized from solid-solutions compositions under different conditions of oxygen fugacities. Larger bodies of pleonaste and ilmenite in Ti-magnetite become lensoid or rounded in outline and these morphological modifications took place during the regional upper amphibolite to lower granulite facies metamorphism at 2.6 Ga ago. The lodestone contains high TiO(2) (20 to 22.59 wt%), with V(2)O(5) (0.85 to 1.15%) and Fe(2)O(3) (t) (72.03 to 74.25%). Ti-magnetite shows alteration to Ti-maghemite, martite and goethite due to low temperature oxidation and hydration during weathering.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | V-Ti magnetite; Sargur schist belt; Microintergrowths; Amphibolite-granulite facies metamorphism; Kurihundi; Dharwar craton; Karnataka |
| Subjects: | F Earth Science > Geology |
| Divisions: | Department of > Earth Science |
| Depositing User: | Users 19 not found. |
| Date Deposited: | 23 Aug 2019 06:10 |
| Last Modified: | 23 Aug 2019 06:10 |
| URI: | http://eprints.uni-mysore.ac.in/id/eprint/6950 |
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