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Deccan volcanism in Rajasthan: Ar-40-Ar-39 geochronology and geochemistry of the Tavidar volcanic suite

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Title Deccan volcanism in Rajasthan: Ar-40-Ar-39 geochronology and geochemistry of the Tavidar volcanic suite
 
Creator SEN, A
PANDE, K
HEGNER, E
SHARMA, KK
DAYAL, AM
SHETH, HC
MISTRY, H
 
Subject Volcanism
Deccan Traps
Tavidar
Rajasthan
India
AGE SPECTRUM TECHNIQUE
A-TYPE GRANITES
IGNEOUS COMPLEX
RB-SR
CHEMICAL CLASSIFICATION
SOUTHWEST RAJASTHAN
NORTHWESTERN INDIA
CONTINENTAL-CRUST
ARAVALLI CRATON
THERMAL EVENT
 
Description The Tavidar volcanic suite in western Rajasthan, India, comprises a group of lava flows (and subordinate pyroclastic deposits) of highly diverse compositions ranging from basalt through trachyte to rhyolite. We have dated five samples of the Tavidar volcanic rocks by the Ar-40-Ar-39 incremental heating technique. One trachyte and two rhyolite samples yield very good plateau. isochron and inverse isochron ages of 67-65 Ma, typical of the Deccan Traps large igneous province. A subalkalic basalt and a basaltic trachyandesite yield saddle-shaped argon release spectra and show evidence for excess argon. Importantly, all five samples have very similar Nd-Sr isotopic ratios, and constitute a broadly cogenetic magmatic suite with the rhyolites possibly derived by closed-system fractional crystallization of trachytic magmas. The Tavidar rocks' isotopic data overlap, or are very close to, those of the Mahabaleshwar and Panhala Formation basalts in the Western Ghats type section 700-800 km to the southeast. We therefore infer that the Tavidar rocks, having initial Nd values of +3.2 to +0.7, have incorporated only small amounts of lower continental crust. The Tavidar volcanic suite attests to the great areal extent of the Deccan Traps, and reaffirms the great compositional diversity evident in the northwestern Deccan Traps. (C) 2012 Elsevier Ltd. All rights reserved.
 
Publisher PERGAMON-ELSEVIER SCIENCE LTD
 
Date 2014-10-15T08:46:37Z
2014-10-15T08:46:37Z
2012
 
Type Article
 
Identifier JOURNAL OF ASIAN EARTH SCIENCES, 59127-140
http://dx.doi.org/10.1016/j.jseaes.2012.07.021
http://dspace.library.iitb.ac.in/jspui/handle/100/14719
 
Language en