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Ignimbrite flows from Rajula, Saurashtra, India

Published online by Cambridge University Press:  01 May 2009

T. Krishnamacharlu
Affiliation:
Centre of Advanced Study in GeologyUniversity of SagarSagar 470-003, M.P., India

Summary

The paper records the occurrence of ignimbrite flows at Rajula, Amreli district of Saurashtra. Three different flows of ignimbrite representing a single genetic unit have been recognized. They consist of devitrified glass shards, pumice, salic and mafic minerals and unevenly distributed basic fragments. The shards and pumice are elongated along the flow direction of the rock giving eutaxitic foliation, while the basic fragments are drawn out in the direction of flow. The low content of soda in these ignimbrites is probably due to its loss during the hydration and devitrification of the glass.

Type
Articles
Copyright
Copyright © Cambridge University Press 1974

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References

Aramaki, S. & Lipman, P. 1965. Possible leaching of Na2O during hydration of volcanic glasses. Proc. Jap. Acad. 41, 467–70.CrossRefGoogle Scholar
Chatterjee, S. C. 1961. Petrology of the lavas of Pavagad hill, Gujarat. J. geol. Soc. Ind. 2, 6177.Google Scholar
Cook, E. F. 1963. Ignimbrites of the Great Basin, USA. Bull. Volcan. 25, 8996.CrossRefGoogle Scholar
Lipman, P. W. 1965. Chemical comparison of glassy and crystalline volcanic rocks. Bull. U.S. Geol. Surv. 1201-D, D1D24.Google Scholar
Lofgren, G. 1970. Experimental devitrification rate of rhyolite glass. Bull. geol. Soc. Am. 81, 553–60.CrossRefGoogle Scholar
Noble, D. C. 1965. Groundwater leaching of sodium from quickly cooled volcanic rocks (Abstract). Am. Miner. 50, 289.Google Scholar
Noble, D. C. 1967. Sodium, potassium, and ferrous iron contents of some secondarily hydrated natural silicic glasses. Am. Miner. 52, 280–6.Google Scholar
Orville, P. M. 1963. Alkali ion exchange between vapor and feldspar phase. Am. J. Sci. 261, 201–37.CrossRefGoogle Scholar
Ray, P. S. 1960. Ignimbrite in the Kilchrist vent, Skye. Geol. Mag. 97, 229–38.CrossRefGoogle Scholar
Ross, C. S. & Smith, R. L. 1961. Ash-flow tuffs: their origin geologic relations and identification. Prof. Pap. U.S. geol. Surv. 366, 181.Google Scholar
Schmincke, H. & Swanson, D. A. 1967. Laminar viscous flowage structures in ash-flow tuffs from Gran Canaria, Canary Islands. J. Geol. 75, 641–64.CrossRefGoogle Scholar
Scott, R. B. 1966. Origin of chemical variations within ignimbrite cooling units. Am. J. Sci. 264, 273–88.CrossRefGoogle Scholar
Scott, R. B. 1971. Alkali-exchange during devitrification and hydration of glasses in ignimbrite cooling units. J. Geol. 79, 100–10.CrossRefGoogle Scholar
Smith, R. L. 1960(a). Zones and zonal variations in welded ash flows. Prof. Pap. U.S. geol. Surv. 354-F, 149–59.Google Scholar
Smith, R. L. 1960(b). Ash flows. Bull. geol. Soc. Am. 71, 795842.CrossRefGoogle Scholar
Subba Rao, S. 1971. Petrogenesis of the acid igneous rocks of the Deccan Traps. Bull. volcan. 35, 983–97.Google Scholar
Talati, D. J. 1970. On the presence of explosive volcanic activity in some Deccan Trap areas. Mineral Wlth 6, 1315.Google Scholar
Wager, L. R. & Bailey, E. B. 1953. Basic magma chilled against acid magma. Nature, Lond. 172, 68–9.CrossRefGoogle Scholar
Wakhaloo, S. N. 1967. On the nature of volcanic eruption and of differentiation of the Girnar igneous complex, Junagarh, Kathiawar peninsula, India. Symp. Upper Mantle Project, Hyderabad, 430–9.Google Scholar
Walker, G. P. L. 1962. Tertiary welded tuffs in Eastern Iceland. Q. Jl geol. Soc. Lond. 118, 275–93.CrossRefGoogle Scholar