Alkaline rocks occur in all tectonic environments, including the ocean basins. Alkaline rocks are generally considered to have more alkalis than can be accommodated by feldspars alone. The excess alkalis then appear in feldspathoids, sodic pyroxenes/amphiboles or other alkali-rich phases. Alkaline rocks generally occurs in three principal settings :- Some important igneous Alkaline rocks are […]
The structure of the Dharwar Craton is interpreted in terms of a foreland in the west and an accretionary complex in the east. The older sequence that shows a relatively higher degree of metamorphism and intrusive contact with the granitic and gneisses has been named as Sargur Group. The granitic gneisses that show intrusive contact
The Cretaceous rocks consists of thick succession of marine sequences that ranges in age from Aptian to Maastrichtian. The marine sequences represents at least four phases of marine transgression that were interrupted by brief periods of withdrawal of marine conditions. The marine transgression leads to the deposition of four groups as Dalmiapurum, Uttatur, Trichinopoly and
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Mesozoic rocks of kutch were deposited in rift basins that developed during the Late Triassic (Rhaetian). The basin was filled with syn-rift Middle Jurassic to Early Cretaceous sediments and post-rift Late Paleocene to Pliocene and Quarternary sediments. The Mesozoic marine sediments show characters of siliclastic ramp, carbonate ramp, storm dominated shallow shelf carbonates, and fine
The fossiliferous Lower Paleozoic rocks either rests conformably over the un-fossiliferous sequence named as Dogra Slate or unconformably over the crystalline rocks comprising Salkhala Group. The succession begins with Hapatnar Group of Late Cambriam to Silurian age which is overlain successive formations of Middle and Upper Paleozoic. Stratigraphy of the area :- Stratigraphic Unit Lithology
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Precambrian basement of central India is made up of two cratonic domains, the Aravalli-Bundelkhand craton in the North and Bastar craton in the South. They are separated by a ENE-WSW trending Narmada-Son lineament. This zone has been named as Central India Tectonic Zone. CITZ contains fragments of both, the northern and the southern cratonic domains.
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The Vindhyan Supergroup is named after the scarped plateau mountains in the north of the Narmada Valley. Vindhyan basin is canceled under the Deccan Traps of the Malwa Plateau and the Quaternary sediments. The basin evolved as a vast intra-cratonic basin formed in response to intraplate stresses. The Vindhyan Basin was formed as a result
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The Neogene rocks are exposed in the Siwalik Hills and other foot hill comprising the Outer Himalaya. Siwalik group is a thick succession of medium to coarse sandstone, conglomerate and clay. Base is not exposed.
The Eastern Ghats Mobile Belt (EGMB) comprises densely forested hilly tract along the eastern coast of the Indian Peninsula. It extends from Brahmni river in north of Cuttack in Orissa to Ongole in Andhra Pradesh. It comprises gneiss, charnokites and khondalites of largely Neoarchean to Mesoproterozoic ages. These rocks were subjected to multiple events of
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