Tamil Nadu
Geological field work was carried out in eight different areas of Tamil Nadu, namely Ariyalur, Kadavur, Chalk hills, Kanjamalai, Yercaud, Samalpatti-Sevatur-Koratti, Elagiri hills and Rasimalai. The various rock types and fossil assemblages of the area, including the related economic mineral deposits and structural features associated with the outcrops was studied.
Ariyalur - Cretaceous rocks that dominate these regions are largely exposed in the north-western part of the Cauvery basin. The importance of these Cretaceous deposits lies in the development of their diverse lithofacies, abundance and variety of fossils and a wide geographical distribution in the region. The entire sequence is a shallow marine sequence. The main highlights of the study included the visit to the Terani clay mines and Sattanur Fossil Park, and studying the sedimentary rocks like Uttatur potato, Karai shales, and badland topography with (gypsum and phosphatic nodules; belemnite fossils).
Kadavur - Kadavur lies in Karur district of Tamil Nadu, where more than 90 percent of the district is underlain by hard rock of Archean age. The main locations visited were part of a gabbro-anorthosite igneous complex intruding into migmatitic gneisses exposed in a plain terrain, and surrounded by hills consisting of quartzite. Anorthosite and gabbroic rocks intrude into an anticline composed of quartz schist and quartzite in Kadavur. It intrudes the Precambrian migmatitic gneisses and metasediments and is surrounded by sillimanite bearing quartz rich metasediments and calc-granulites.
Chalk hills - Chalk hills, Salem, Tamil Nadu, host the major magnesite deposit in South India. Vein type magnesite mineralisation is confined to fractures in the dunite and peridotite and is restricted to extensively serpentinised and weathered portions of the ultramafics. These host rock - mineralisation was studied from TANMAG mines.
Kanjamalai - Is a structural hill in Salem district. It is well known on account of magnetite iron ore deposits located at a distance of 8 km west of Salem town. Kanjamalai is a part of the Salem Block which is a part of the Southern Granulite Terrain. Kanjamalai constitutes a mixed terrain comprised of charnockites, mafic granulites and BIF, surrounded by amphibolites, hornblende biotite schist, granite gneisses and migmatites.The Banded Iron Formations are deposited during the Pre-Cambrian ages. Significant structural features like the S, Z, and W/M type of banding in the BIFs are the highlights of this region.
Yercaud - Yercaud is a hill station in Salem District, in Tamil Nadu, India. In this region, the metamorphic rocks are capped by laterites. The main rock types of the region include charnockite, khondalites, and bauxites.
Samalpatti-Sevattur - The Samalpatti carbonatite complex is situated in Dharmapuri, Tamilnadu. The complex comprises of carbonatite occurrences at Pallasulakkarai, Garikalpalli, Onnakarai, Olapatti, Jogipatti, Tipampatti and Sinampatti. This carbonatites are tectonically emplaced along fault/fracture of Neoproterozoic Koratti Fault Zone and predominantly calcio-carbonatite to ferro-carbonatite. At the Sevattur vermiculite mine, the carbonatite intrusion into the pyroxenite was witnessed. In the contact zone between the two vermiculte is present.
Elagiri - The Elagiri complex represents one of the important silica-oversaturated syenite plutons of the Southern Granulite Terrane of the Indian shield. The country rocks are foliated bearing evidences of multiple folding and deformation. The constituent litho-members of the Elagiri complex (syenites, gabbro and later intrusives marked by lamprophyre and carbonatite) show preservation of igneous layering
Rasimalai - Rasimalai is a region distinctively studied for the radioactivity because of the presence of the various radioactive minerals in the syenite. The Rasimalai syenite occurs as an intrusive pluton into the gneisses.