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Kumar, Vinod
- Quench-Textured Alkali Olivine Basalts from Jungel-Valley, Mirzapur District, Uttar Pradesh, India
Authors
1 Geological Survey of India, Petrology Division Aliganj Extension, Lucknow 226020, IN
2 Department of Geology, Government Science College, Jabalpur, 482001 M.P., IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 35, No 2 (1990), Pagination: 173-182Abstract
Alkali olivine basalts of Jungel metavolcanic suite in Bijawar greenstone belt of Central India display various morphologies of quench crystals indicative of rapid cooling or supercooling. There is resemblance between crystal growths of the present area and those described from submarine basalts and experimentally produced crystals under disequilibrium conditions. Stratigraphy, structural and petrographic characters of these rocks demonstrate that they represent an ancient oceanic crust.Keywords
Petrology, Genesis, Quench-Texture, Basalt, Jungel-Valley, Bijawar Greenstone Belt, Mirzapur, Uttar Pradesh.- Volcanological Aspects of Jungel Metavolcanic Suite, Bijawar Greenstone Belt, Central India: Suspect Ancient Island-Arc Volcanism
Authors
1 Petrology Division, Geological Survey of India, Aliganj Extension, Lucknow-226 020, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 39, No 4 (1992), Pagination: 338-347Abstract
Spectacular array of volcanic structures shown by Jungel metavolcanics include pillow structures, pahoehoe flows and toes, groove lava and shark tooth projections. Some of these features are indicative of small volume phreato-magmatic eruptions under shallow water conditions. The style of igneous activity is inferred to be moderately explosive, fragmental and spasmodic, supported by substantial. amount of volatiles. Based on volcanological, geochemical and tectonic evidences it is suggested that the present volcanic rocks were erupted in island-arc environment and that the southern margin of the Bundelkhand protocontinent formed a zone of subduction.Keywords
Bijawar Greenstone Belt, Volcanogenic, Island-Arc Volcanism.- Petrography and Geochemistry of Jungel Metavolcanics, Bijawar Greenstone Belt, Central India : A Picritic Basalt Low K-Andesite Association
Authors
1 Petrology Division, Geological Survey of India, Aliganj Extension, Lucknow-226 020, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 41, No 1 (1993), Pagination: 9-19Abstract
Jungel valley is known to have dominant magmatic rocks of basaltic affinity evolved on ancient oceanic crust. It consists of alkali picritic basalt (APB) - alkali olivine basalt (AOB) - low potassic andedsite (LKA) association besides those earlier reported lava flows, tuffs, agglomerates and lamprophyres. These rocks were emplaced along numerous fractures in the earth's crust caused by N-S compressional forces at the time of Satpura orogeny in a rifted back are tectonic setting.
Chemically the APB and AOBs are characterized by high MgO, mg values, CaO, TiO2 and P2O5 contents and depleted in SiO2, Al2O3 and K2O The APB is considered to be parental/primitive magma formed by varying degree of melting of garnet peridotite from the mantle. This source, however, was heterogeneous in respect of K, P and Rb contents similar to Sunda-Banda arc. The geochemical evolution of these rocks is shown to have analogy with some modem island arcs eg. Dunedian and Sunda-Banda arcs. Major elements, SiO2, Al2O3, Na2O, K2O, TiO2 and FeO1 show increase with increasing differentiation from APB to LKA while CaO and MgO have inverse relationship.
The basalts are enriched in both transitional and incompatible elements, whereas, andesite is depleted in these. Cu has followed silicate phase, while Pb and Zn have remained in residual liquids as in Dunedian arc rocks.
Keywords
Bijawar Greenstone Belt, Jungel Metavolcanics, Picritic Basalt, Andesite.- Petrography, Geochemistry and Petrogenesis of Alkali Lamprophyres of Jungel Suite, Central India
Authors
1 Operation U.P., Geological Survey of India. Aliganj Extension, Lucknow - 226 020, IN