Structural fabric of the Southern Indian shield as defined by gravity trends

Kumar, Niraj; Singh, Arun; Singh, Bijendra

doi:10.1016/j.jseaes.2008.08.009

Cited by 16 publications

(11 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It would now be imperative to search for imprints of major tectonic event that made the upper mantle comparatively weak. Recently, a similar upper mantle density beneath the Southern Granulite Terrain is hypothesized as a highly remobilised lithosphere due to crustal delamination (Singh et al, 2006, in press;Niraj Kumar et al, 2009a,b, 2010. Chemical stratification of the Indian lithospheric mantle with the upper lithosphere (up to 80 km) comprising of the spinel peridotite (of lower density) and the lower lithosphere with that of garnet peridotite composition (of higher density) may be the other distinct possibility (Jagadeesh and Rai, 2008).…”

Section: Discussionmentioning

confidence: 99%

Crustal density structure across the Central Indian Shear Zone from gravity data

Rao

Kumar

Singh

et al. 2011

Journal of Asian Earth Sciences

Self Cite

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Crustal density structure across the Central Indian Shear Zone from gravity data

Rao

Kumar

Singh

et al. 2011

Journal of Asian Earth Sciences

Self Cite

View full text Add to dashboard Cite

“…The structural/tectonic [ Chardon et al ., ] and horizontal Bouguer gravity gradient map of the region [ Kumar et al ., ], along with the induction vectors, were used to resolve the 90° ambiguity in strike determination (Figure ). The tectonic features (shear zones) in the area show N‐S to NW‐SE orientations, and most of these are well reflected in the horizontal Bouguer gravity gradient map (Figure ).…”

Section: Present Mt Studymentioning

confidence: 99%

“…[]) and horizontal Bouguer gravity gradient (data after Kumar et al . []) trends in the western Dharwar craton. Inset shows the representative real induction vectors (Parkinson convention) for the 100–1000 s period band.…”

Section: Present Mt Studymentioning

confidence: 99%

The electrical resistivity structure of lithosphere across the Dharwar craton nucleus and Coorg block of South Indian shield: Evidence of collision and modified and preserved lithosphere

et al. 2015

View full text Add to dashboard Cite

Magnetotelluric-derived two-dimensional lithospheric resistivity structure of the western Dharwar craton (WDC) and adjoining Coorg block indicates isolated low-resistivity zones in the crust and three striking upper mantle conductive features within the highly resistive Archean lithosphere. The crustal conductors in the WDC show good spatial correlation with the exposed supracrustal rocks conformable with the relic schist belt channels having conductive mineral grains. Conductive zones within the Coorg crust might be related to the relatively young (933 Ma) metamorphic processes in the area and/or possible fluids derived from the Cretaceous passage of Reunion plume in the proximity of Coorg area. A near-vertical conductive structure extending from the lower crust into the upper mantle coincides with the transition zone between Coorg and WDC. This is interpreted as the suture zone between the two tectonic blocks and provides evidence for the individuality of the two Archean terrains. An anomalous upper mantle conductive zone found beneath the craton nucleus may indicate a modified cratonic lithosphere. This could have been derived due to the collision between Coorg and WDC and possibly survived by the subsequent multiple episodes of melt and fluid infiltration processes experienced in the region. Thick (~190 km) and preserved lithosphere is mapped at the eastern segment of WDC. Resistive lithosphere of~125 km thickness is imaged for the Coorg block.

show abstract

“…Based on gravity data collected at 7,862 stations and merged with an almost equal amount of the available data, a gravity anomaly map (Figs. 3a, 4a) of the region was prepared (GMSI, 2006;NIRAJ KUMAR et al, 2009). The geodetic survey team provided the position location and elevation of about 1,100 gravity stations along the Kuppam-Kanyakumari seismic line.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Crustal Structure and Geodynamic Evolution of the Southern Granulite Terrain, India, from Isostatic Considerations

Kumar

Singh

2010

Pure Appl. Geophys.

Self Cite

View full text Add to dashboard Cite

The Southern Granulite Terrain of India, formed through an ancient continental collision and uplift of the earth's surface, was accompanied by thickening of the crust. Once the active tectonism ceased, the buoyancy of these deep crustal roots must have supported the Nilgiri and Palani-Cardamom hills. Here, the gravity field has been utilized to provide new constraints on how the force of buoyancy maintains the state of isostasy in the Southern Granulite Terrain. Isostatic calculations show that the seismically derived crustal thickness of 43-44 km in the Southern Granulite Terrain is on average 7-8 km more than that required to isostatically balance the present-day topography. This difference cannot be solely explained applying a constant shift in the mean sea level crustal thickness of 32 km. The isostatic analysis thus indicates that the current topography of the Southern Granulite Terrain is overcompensated, and about 1.0 km of the topographic load must have been eroded from this region without any isostatic readjustment. The observed gravity anomaly, an order of magnitude lower than that expected (-125 mGal), however, shows that there is no such overcompensation. Thermal perturbations up to Pan-African, present-day high mantle heat flow and low Te together negate the possible resistance of the lithosphere to rebound in response to erosional unloading. To isostatically compensate the crustal root, compatible to seismic Moho, a band of high density (2,930 kg m -3 ) in the lower crust and low density (3,210 kg m -3 ) in the lithospheric mantle below the Southern Granulite Terrain is needed. A relatively denser crust due to two distinct episodes of metamorphic phase transitions at 2.5 Ga and 550 Ma and highly mobilized upper mantle during Pan-African thermal perturbation reduced significantly the root buoyancy that kept the crust pulled downward in response to the eroded topography.

show abstract

Structural fabric of the Southern Indian shield as defined by gravity trends

Cited by 16 publications

References 45 publications

Crustal density structure across the Central Indian Shear Zone from gravity data

Crustal density structure across the Central Indian Shear Zone from gravity data

The electrical resistivity structure of lithosphere across the Dharwar craton nucleus and Coorg block of South Indian shield: Evidence of collision and modified and preserved lithosphere

Insights into the Crustal Structure and Geodynamic Evolution of the Southern Granulite Terrain, India, from Isostatic Considerations

Contact Info

Product

Resources

About