Complex shallow mantle beneath the Dharwar craton inferred from Rayleigh wave inversion Geophysical Journal International

Borah, Kajaljyoti and Rai, S. S. and Priestley, Keith F. and Gaur, V. K. (2014) Complex shallow mantle beneath the Dharwar craton inferred from Rayleigh wave inversion Geophysical Journal International. Geophysical journal international, 198 (2). pp. 1055-1070. ISSN Online ISSN 1365-246X Print ISSN 0956-540X DOI 10.1093/gji/ggu185

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Official URL: http://gji.oxfordjournals.org/content/198/2/1055.a...

Abstract

The 3-D shear velocity structure beneath South India's Dharwar Craton determined from fundamental mode Rayleigh waves phase velocities reveals the existence of anomalously high velocity materials in the depth range of 50–100 km. Tomographic analysis of seismograms recorded on a network of 35 broad-band seismographs shows the uppermost mantle shear wave speeds to be as high as 4.9 km s–1 in the northwestern Dharwar Craton, decreasing both towards the south and the east. Below ∼100 km, the shear wave speed beneath the Dharwar Craton is close to the global average shear wave speed at these depths. Limitations of usable Rayleigh phase periods, however, have restricted the analysis to depths of 120 km, precluding the delineation of the lithosphere–asthenosphere boundary in this region. However, pressure–temperature analysis of xenoliths in the region suggests a lithospheric thickness of at least ∼185 km during the mid-Proterozoic period. The investigations were motivated by a search for seismic indicators in the shallow mantle beneath the distinctly different parts of the Dharwar Craton otherwise distinguished by their lithologies, ages and crustal structure. Since the ages of cratonic crust and of the associated mantle lithosphere around the globe have been found to be broadly similar and their compositions bimodal in time, any distinguishing features of the various parts of the Dharwar shallow mantle could thus shed light on the craton formation process responsible for stabilizing the craton during the Meso- and Neo-Archean.

Item Type: Article
Additional Information: This article has been accepted for publication in Geophysical Journal International ©: 2014 © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved.
Uncontrolled Keywords: 2014AREP; IA67;
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
08 - Green Open Access
Journal or Publication Title: Geophysical journal international
Volume: 198
Page Range: pp. 1055-1070
Identification Number: 10.1093/gji/ggu185
Depositing User: Sarah Humbert
Date Deposited: 28 Apr 2014 10:13
Last Modified: 27 Oct 2014 17:04
URI: http://eprints.esc.cam.ac.uk/id/eprint/3031

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