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Geochemistry of the Palitana flood basalt sequence and the Eastern Saurashtra dykes, Deccan Traps: clues to petrogenesis, dyke-flow relationships, and regional lava stratigraphy

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Title Geochemistry of the Palitana flood basalt sequence and the Eastern Saurashtra dykes, Deccan Traps: clues to petrogenesis, dyke-flow relationships, and regional lava stratigraphy
 
Creator SHETH, HC
ZELLMER, GF
KSHIRSAGAR, PV
CUCCINIELLO, C
 
Subject Volcanism
Deccan Traps
Flood basalt
India
Saurashtra
Palitana
MANTLE SOURCES
VOLCANIC PROVINCE
CONTINENTAL-CRUST
IGNEOUS COMPLEX
PICRITE BASALTS
TRACE-ELEMENT
WESTERN INDIA
MOUNT GIRNAR
PB-ISOTOPE
GUJARAT
 
Description Recent studies of large mafic dyke swarms in the Deccan Traps flood basalt province, India, indicate that some of the correlative lava flows reached several hundred kilometers in length. Here we present field, petrographic, mineral chemical, and whole-rock geochemical (including Sr-Nd isotopic) data on the Palitana lava sequence and nearby dykes in the Saurashtra region of the northwestern Deccan Traps. These rocks are moderately evolved, many with low-Ti-Nb characteristics. We infer that most dykes are notably (and systematically) less contaminated by ancient continental crust than the Palitana flows, but four dykes are equally or significantly more contaminated, with some of the most extreme Sr-Nd isotopic compositions seen in the entire Deccan Traps (initial epsilon(Nd) is as low as -18.0). A Bhimashankar-type and a Poladpur-type dyke are present several hundred kilometers from the type section of these magma types in the Western Ghats escarpment. We find no geochemical correlations between the Palitana sequence and three subsurface sequences in NE Saurashtra containing abundant picritic rocks, surface lavas previously studied from Saurashtra, or the Western Ghats sequence. Intriguingly, the Eastern Saurashtra dykes cannot have been feeders to any of these lava sequences. Feeder dykes of these sequences may be located in southwestern or central Saurashtra, or in the Dhule-NandurbarDediapada areas across the Gulf of Cambay, 200-300 km east of Palitana. Our results indicate polycentric flood basalt eruptions not only on the scale of the Deccan Traps province, but also within the Saurashtra region itself.
 
Publisher SPRINGER
 
Date 2014-10-15T08:24:41Z
2014-10-15T08:24:41Z
2013
 
Type Article
 
Identifier BULLETIN OF VOLCANOLOGY, 75(4)
http://dx.doi.org/10.1007/s00445-013-0701-x
http://dspace.library.iitb.ac.in/jspui/handle/100/14676
 
Language en