Complex shallow mantle beneath the Dharwar Craton inferred from Rayleigh wave inversion

Borah, Kajaljyoti; S., S.; Gaur, V. K.

doi:10.1093/gji/ggu185

Cited by 27 publications

(16 citation statements)

References 41 publications

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“…Significant differences are observed in the crustal and upper mantle structure of these two blocks. The WDC crust is 10–15 km thicker, with a predominantly mafic composition as suggested from surface wave dispersion [ Borah et al ., ] and receiver function studies [ Gupta , ; Kiselev et al ., ]. Beneath the WDC, we observe a thick (~50 km) slow velocity layer (Figure : H5‐H6 and V1‐V2 and Figure : X3‐X4) at around 50–100 km depth and a thick lithosphere with the presence of ~2% faster velocity down to ~160 km.…”

Section: Lithospheric Model For Different Blocksmentioning

confidence: 99%

Imaging the lithospheric structure beneath the Indian continent

et al. 2016

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We present a high‐resolution 3‐D lithospheric model of the Indian plate region down to 300 km depth, obtained by inverting a new massive database of surface wave observations, using classical tomographic methods. Data are collected from more than 550 seismic broadband stations spanning the Indian subcontinent and surrounding regions. The Rayleigh wave dispersion measurements along ~14,000 paths are made in a broad frequency range (16–250 s). Our regionalized surface wave (group and phase) dispersion data are inverted at depth in two steps: first an isotropic inversion and next an anisotropic inversion of the phase velocity including the SV wave velocity and azimuthal anisotropy, based on the perturbation theory. We are able to recover most of the known geological structures in the region, such as the slow velocities associated with the thick crust in the Himalaya and Tibetan plateau and the fast velocities associated with the Indian Precambrian shield. Our estimates of the depth to the Lithosphere‐Asthenosphere boundary (LAB) derived from seismic velocity Vsv reductions at depth reveal large variations (120–250 km) beneath the different cratonic blocks. The lithospheric thickness is ~120 km in the eastern Dharwar, ~160 km in the western Dharwar, ~140–200 km in Bastar, and ~160–200 km in the Singhbhum Craton. The thickest (200–250 km) cratonic roots are present beneath central India. A low velocity layer associated with the midlithospheric discontinuity is present when the root of the lithosphere is deep.

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Section: Lithospheric Model For Different Blocksmentioning

confidence: 99%

Imaging the lithospheric structure beneath the Indian continent

et al. 2016

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“…However, determining continental residual topography is less straightforward since the density and thickness of heterogeneous crust and lithospheric mantle are relatively poorly known. An appropriate starting point is a database of crustal thickness measurements assembled from a combination of seismic refraction experiments and receiver function analyses [ Kaila , ; Kaila et al ., ; Saul et al ., ; Ravi Kumar et al ., ; Sarkar et al ., ; Gupta et al ., ; Reddy , ; Tiwari et al ., ; Jagadeesh and Rai , ; Mitra et al ., ; Julià et al ., ; Acton et al ., ; Behera , ; Kayal et al ., ; Mandal , ; Borah et al ., ; Praveen Kumar and Mohan , ; Singh et al ., ] (Figure 5; Supporting Information S1; Data Set S1). Bulk P wave velocities are 6.23–6.89 km s −1 which yield average crustal densities of 2.76–2.9 Mg m −3 , according to empirical velocity‐density relationships [ Brocher , ; Maceira and Ammon , ].…”

Section: Regional Frameworkmentioning

confidence: 99%

“…Geochemistry, Geophysics, Geosystems 10.100210. /2016GC006545 2001Sarkar et al, 2003;Gupta et al, 2003;Reddy, 2005;Tiwari et al, 2006;Jagadeesh and Rai, 2008;Mitra et al, 2008;Juli a et al, 2009;Acton et al, 2011;Behera, 2011;Kayal et al, 2011;Mandal, 2012;Borah et al, 2014;Praveen Kumar and Mohan, 2014;Singh et al, 2015] (Figure 5; Supporting Information S1; Data Set S1). Bulk P wave velocities are 6.23-6.89 km s 21 which yield average crustal densities of 2.76-2.9 Mg m 23 , according to empirical velocity-density relationships [Brocher, 2005;Maceira and Ammon, 2009].…”

Section: Crustal and Lithospheric Isostasymentioning

confidence: 99%

“…[Priestley and McKenzie, 2013] (Supporting Information Data Set S1). Stars 5 crustal thicknesses calculated by joint inversion of receiver functions and surface wave dispersion curves [e.g., Rai, 2003;Juli a et al, 2009;Rai et al, 2009;Acton et al, 2010Acton et al, , 2011Vijay Kumar et al, 2012;Mandal, 2012;Borah et al, 2014]; squares 5 crustal thicknesses from inverse modeling of receiver functions [e.g., Mitra et al, 2008;Kayal et al, 2011;Singh et al, 2012;Praveen Kumar and Mohan, 2014]; dots 5 crustal thicknesses calculated by either forward modeling or H-k stacks of receiver functions [e.g., Saul et al, 2000;Ravi Kumar et al, 2001;Gupta et al, 2003;Rai et al, 2005;Pathak et al, 2006;Tiwari et al, 2006;Jagadeesh and Rai, 2008;Rai et al, 2013]. (b) Crustal thickness plotted as function of elevation for different lithospheric thicknesses.…”

Section: Flexural Analysismentioning

confidence: 99%

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Cenozoic epeirogeny of the Indian peninsula

Richards

Hoggard

White

2016

Geochem Geophys Geosyst

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Peninsular India is a cratonic region with asymmetric relief manifest by eastward tilting from the 1.5 km high Western Ghats escarpment toward the floodplains of eastward‐draining rivers. Oceanic residual depth measurements on either side of India show that this west‐east asymmetry is broader scale, occurring over distances of > 2000 km. Admittance analysis of free‐air gravity and topography shows that the elastic thickness is 10 ± 3 km, suggesting that regional uplift is not solely caused by flexural loading. To investigate how Indian physiography is generated, we have jointly inverted 530 river profiles to determine rock uplift rate as a function of space and time. Key erosional parameters are calibrated using independent geologic constraints (e.g., emergent marine deposits, elevated paleosurfaces, uplifted lignite deposits). Our results suggest that regional tilt grew at rates of up to 0.1 mm a−1 between 25 Ma and the present day. Neogene uplift initiated in the south and propagated northward along the western margin. This calculated history is corroborated by low‐temperature thermochronologic observations, by sedimentary flux of clastic deposits into the Krishna‐Godavari delta, and by sequence stratigraphic architecture along adjacent rifted margins. Onset of regional uplift predates intensification of the Indian monsoon at 8 Ma, suggesting that rock uplift rather than climatic change is responsible for modern‐day relief. A positive correlation between residual depth measurements and shear wave velocities beneath the lithosphere suggests that regional uplift is generated and maintained by temperature anomalies of ±100 °C within a 200 ± 25 km thick asthenospheric channel.

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“…Bodin et al (2014) inferred an ~200-km-thick lithosphere beneath the eastern Dharwar craton and a midlithospheric low-velocity region at a depth of ~100 km. An improved surface-wave tomography image of the Dharwar craton reveals a layered lithosphere with a high shear-wave velocity (Vs ~4.7-4.9 km/s) in the depth range of 40-100 km, followed by a normal mantle velocity of 4.5 km/s (Borah et al, 2014). Presence of an extremely high-velocity shallow layer is argued as indicative of mineralogy/ lithology (e.g., dunite that contains olivine and has high seismic anisotropy).…”

Section: Introductionmentioning

confidence: 99%

Upper-mantle anisotropy beneath the south Indian Shield: Influenced by ancient and recent Earth processes

Kumar

Prakasam

et al. 2015

Lithosphere

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We obtained shear-wave splitting parameters from core-refracted phases like SKS, SKKS, and PKS at 75 digital broadband seismic stations almost uniformly spread over the south Indian Shield representing varied geological terrains, including the western Dharwar craton, the eastern Dharwar craton, the Southern granulite terrain, and the continental margins along the west and east coasts. A majority of the stations over the Dharwar craton show delay times of 1-1.6 s, indicative of a 150-200-km-thick anisotropic layer correlating with the lithospheric root, while segments like the Pan-African Southern granulite terrain have delay times of 0.5-0.7 s, suggesting an internally deformed and thin anisotropic layer, possibly due to recent plate-tectonic and geodynamic processes. The average direction of anisotropy is generally ~N30°E, correlating with the present-day plate motion, with local deviations where the direction of anisotropy correlates with the orientation of the regional shear zones. Stations close to the continental margin show large time delays (up to 2 s) with the fast axis parallel to the rift axis. Further, we infer a layered anisotropic lithosphere in the south Indian Shield as revealed in 90° periodicity of the two anisotropy parameters (fast direction and delay time). The upper lithosphere represents the depleted Archean mantle, while the lower lithosphere could be transformed to more fertile mantle due to subsequent deformation. This study suggests that the observed anisotropy over the south Indian Shield is the result of complex interplay between the architecture of an Archean craton and its subsequent deformation in different geological domains due to deep Earth processes.

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Complex shallow mantle beneath the Dharwar Craton inferred from Rayleigh wave inversion

Cited by 27 publications

References 41 publications

Imaging the lithospheric structure beneath the Indian continent

Imaging the lithospheric structure beneath the Indian continent

Cenozoic epeirogeny of the Indian peninsula

Upper-mantle anisotropy beneath the south Indian Shield: Influenced by ancient and recent Earth processes

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