Heterogeneous lithosphere and the underlying mantle of the Indian subcontinent

Kosarev, G. L.; Oreshin, Sergey; Vinnik, Lev; Киселев, С. В.; Dattatrayam, R. S.; Suresh, G.; Baidya, P. R.

doi:10.1016/j.tecto.2013.02.023

Cited by 46 publications

(10 citation statements)

References 41 publications

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“…The vertical passage time for seismic P waves to the 410 km discontinuity is close to that predicted by the ak135 reference model beneath the key cratonic segments of the Indian shield: (Kumar and Mohan, 2005;Ramesh et al, 2005;Rai et al, 2009b;Kiselev et al, 2008;Oreshin et al, 2011;Kosarev et al, 2013;Kumar et al, 2013a). This 'normal' behaviour is rather different from that for other shield regions around the globe, where thick, fast, lithospheric roots have resulted in an elevated 410 discontinuity (Kumar et al, 2013a).…”

Section: Km Discontinuitysupporting

confidence: 70%

“…This 'normal' behaviour is rather different from that for other shield regions around the globe, where thick, fast, lithospheric roots have resulted in an elevated 410 discontinuity (Kumar et al, 2013a). Consistently early passage times, sometimes even close to ∼2 s early, are seen for the 410 km discontinuity from the stations located in the Himalayan mountain belts and its foothills: (Oreshin et al, 2008(Oreshin et al, , 2011Kumar et al, 2013a;Kosarev et al, 2013). The continuity of early arrivals is also maintained for most parts of Ti- (Kumar et al, 2013a).…”

Section: Km Discontinuitymentioning

confidence: 68%

“…Such a scenario is present beneath India, where APM related asthenospheric anisotropy, with SH leading SV is reported using direct S and SKS/SKKS phases (Kumar and Singh, 2008;Saikia et al, 2010). Reports of the Lehmann discontinuity beneath India and Tibet are meagre, (Sharma and Ramesh, 2013;Kiselev et al, 2008;Kosarev et al, 2013;Heit et al, 2010;Oreshin et al, 2011;Wittlinger et al, 2004), but suggest a deeper boundary (> 200 km) than that commonly inferred from S-to-p receiver functions. Beneath the stable parts of Indian shield, the Lehmann discontinuity may define the lithosphere boundary (Gung et al, 2003), revealed in body wave tomographic images.…”

Section: Lithospheric Discontinuities and Transitionsmentioning

confidence: 83%

“…(Singh and Kumar, 2009) have not found any frequency dependence in northeast India close to Himalayan mountain belts, which appears to rule out possibility of water within the mantle transition zone in this area. A low velocity layer atop the 410 discon-tinuity is also reported at few places beneath India (Oreshin et al, 2011;Kosarev et al, 2013;Kumar et al, 2013a), but it remains to be seen how widespread is such a feature, and what the full implications are for water in the transition zone.…”

Section: Km Discontinuitymentioning

confidence: 98%

“…Early vertical passage times compared with the ak135 reference model (Kennett et al, 1995), sometimes even close to ∼ 2 s early are seen for the 660 km discontinuity for regions of Western Tibet, Central India and few parts of Himalaya and Tibet. The early arrivals of 660 near Himalayan collision belt may relate to present day subduction or the the preserved keel of Indian shield (Kosarev et al, 2013), as they are well correlated with the elevation of the 410 discontinuity. Apart from early arrivals or 410 and 660 in the Himalaya, a thick transition zone in the northern part of Indian-subcontinent reflects resting ground for Tethyan slabs within the transition zone itself (Singh and Kumar, 2009).…”

Section: Km Discontinuitymentioning

confidence: 99%

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A review of crust and upper mantle structure beneath the Indian subcontinent

Singh

Kennett

2015

Tectonophysics

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This review presents an account of the variations in crustal and upper mantle structure beneath the Indian subcontinent and its environs, with emphasis on passive seismic results supplemented by results using controlled seismic sources. Receiver function results from more than 600 seismic stations, and over 10,000 km of deep seismic profiles have been exploited to produce maps of average crustal velocities and thickness across the region. The crustal thickness varies from 29 km at the southern tip of India to 88 km under the Himalayan collision zone, and the patterns of variation show significant deviations from the predictions of global models. The average crustal shear velocity (Vs) is low in the Himalaya-Tibet collision zone compared to Indian shield. Major crustal features are: (a) the Eastern Dharwar Craton has a thinner and simpler crustal structure crust than the Western Dharwar Craton, (b) Himalayan crustal thickness picks clearly follow a trend with elevation, (c) The rift zones of the Godavari graben and Narmada-Son lineament show deeper depths of crust than their surroundings, and (d) most of the Indian cratonic fragments, Bundelkhand, Bhandara and Singhbhum, show thick crust in comparison to the Eastern Dharwar Craton. Heat flow and crustal thickness estimates do not show any positive correlations for India. Estimates of the thickness of the lithosphere show large inconsistencies among various techniques not only in terms of thickness but also in the nature of the transition to the asthenosphere (gradual or sharp). The lithosphere beneath India show signs of attrition and preservation in different regions, with a highly heterogeneous nature, and does not appear to have been thinned on broader scale during India's rapid motion north towards 1 Asia. The mantle transition zone beneath India is predominantly normal with some clear variations in the Himalayan region (early arrivals) and Southwest Deccan Volcanic Province and Southern Granulite Terrain (delayed arrivals). No clear patterns on influence on the mantle transition zone discontinuities can be associated with lithospheric thickness. Over 1000 anisotropic splitting parameters from SKS/SKKS phases and 231 using direct S waves are available from various studies. The shear-wave splitting results clearly show the dominance of absolute-plate-motion related strain of a highly anisotropic Indian lithospheric mantle with delay times between the split S phases close to 1 s. There are still many parts of India where there is, at best, limited information on the character of the crust and the mantle beneath. It is to be hoped that further installations of permanent and temporary stations will fill these gaps and improve understanding of the geodynamic environment of the Indian subcontinent.

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