Heterogeneity in crustal structure across the Southern Granulite Terrain (SGT): Inferences from an analysis of gravity and magnetic fields in the Periyar plateau and adjoining areas

Ajayakumar, P.; Kurian, P. John; Rajendran, Suresh; Radhakrishna, M.; Nambiar, C.G.; Mahadevan, Telliyavaram Mahadevan Ponnambalam

doi:10.1016/j.gr.2005.11.011

Cited by 8 publications

(3 citation statements)

References 13 publications

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“…Gravity studies in 2000s have derived inputs from other studies like DSS to model the observed gravity anomalies within the PCSZ region (Singh et al, 2003) or used velocity-density relations for densities (Mishra et al, 2006;. For other gravity studies (Radhakrishna et al, 2003;Ajayakumar et al, 2006) support from DSS and/or MT were not available. Models derived from seismic refraction studies added more ambiguities to our understanding in PCSZ region and moreover the reflection studies across the PCSZ are markedly "noisy".…”

Section: Discussionmentioning

confidence: 99%

“…The gravity studies south of PCSZ in the region west of Kodaikanal show that the upper layer is characterized by exhumed lower crustal rocks (2.76 gm/cm 3 ) and is almost homogeneous. Another study identified a denser lower crust (2.85 gm/cm 3 ) with Moho depth ranging from 36 to 41 km (Ajayakumar et al, 2006). Excluding the earlier model by Singh et al (2003), all the other models (Radhakrishna et al, 2003;Ajayakumar et al, 2006;Mishra et al, 2006; show that the density of mid-lower crustal layers is more than about 2.75 gm/cm 3 for PCSZ and adjoining areas, suggesting relatively high density material beneath this zone.…”

Section: Gravity Studiesmentioning

confidence: 90%

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The Cambrian collisional suture of Gondwana in southern India: A geophysical appraisal

Naganjaneyulu

Santosh

2010

Journal of Geodynamics

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Section: Discussionmentioning

confidence: 99%

Section: Gravity Studiesmentioning

confidence: 90%

The Cambrian collisional suture of Gondwana in southern India: A geophysical appraisal

Naganjaneyulu

Santosh

2010

Journal of Geodynamics

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“…As this geo-transect runs across the NE trending Dharmapuri paleo-rift and the E-W trending Palghat-Cauvery shear zone (Mahadevan 2003), the low density mid-crustal layer and the thickened crust had resulted from the emplacement of large volumes of granitic rocks and alkaline plutons indicating intense crust-mantle interactions (Singh et al 2003). Further, comparison of crustal structure in different parts of the SGT indicated that the seismic data and the derived crustal layering might not be representative of the SGT crust (Ajayakumar et al 2006). On the other hand, the DSS profiles across the Cuddapah basin (Kaila and Bhatia 1981;Kaila and Tewari 1985) revealed four layered velocity structure for the eastern Indian shield crust with Moho mapped at a depth of 35-39 km in the Cuddapah basin.…”

Section: Constrained Potential Field Modellingmentioning

confidence: 92%

Crustal structure and rift tectonics across the Cauvery–Palar basin, Eastern Continental Margin of India based on seismic and potential field modelling

et al. 2016

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The Cauvery-Palar basin is a major peri-cratonic rift basin located along the Eastern Continental Margin of India (ECMI) that had formed during the rift-drift events associated with the breakup of eastern Gondwanaland (mainly India-Sri Lanka-East Antarctica). In the present study, we carry out an integrated analysis of the potential field data across the basin to understand the crustal structure and the associated rift tectonics. The composite-magnetic anomaly map of the basin clearly shows the onshore-tooffshore structural continuity, and presence of several high-low trends related to either intrusive rocks or the faults. The Curie depth estimated from the spectral analysis of offshore magnetic anomaly data gave rise to 23 km in the offshore Cauvery-Palar basin. The 2D gravity and magnetic crustal models indicate several crustal blocks separated by major structures or faults, and the rift-related volcanic intrusive rocks that characterize the basin. The crustal models further reveal that the crust below southeast Indian shield margin is ∼36 km thick and thins down to as much as 13-16 km in the Ocean Continent Transition (OCT) region and increases to around 19-21 km towards deep oceanic areas of the basin. The faulted Moho geometry with maximum stretching in the Cauvery basin indicates shearing or low angle rifting at the time of breakup between India-Sri Lanka and the East Antarctica. However, the additional stretching observed in the Cauvery basin region could be ascribed to the subsequent rifting of Sri Lanka from India. The abnormal thinning of crust at the OCT is interpreted as the probable zone of emplaced Proto-Oceanic Crust (POC) rocks during the breakup. The derived crustal structure along with other geophysical data further reiterates sheared nature of the southern part of the ECMI.

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Some Insights into the Lithospheric Electrical Structure in the Western Ghat Region from Magnetotelluric Studies

Patro

Raju

Sarma

2018

Journal of the Geological Society of India

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Magnetotelluric (MT) studies along a few traverses, some cutting across the Western Ghats, during the last few years have provided basic insights into the shallow as well as the deeper electrical structure in the regions near and east of the Western Ghat belt. The MT models broadly show a two layered lithospheric electrical structure with an upper high resistive layer (several thousands of Ωm) and a lower moderately conductive layer (a few tens to a few hundred Ωm). The depth of the interface between the two layers is found to vary from about 120-160 km in the south in the SGT to around 80 km in the north in the northern DVP. Another impressive feature that could be noticed in these electrical models is the presence of well-defined major near vertical crustal conductive feature associated with the region of Western Ghat belt, presumably associated with the tectonic evolution of the Western Ghats. Further, these models also brought out several other well-defined conductors that might be linked to structural features like faults, shear zones, etc., in the region. These conductors pierce through the crustal column and some of these, particularly those oriented in NW-SE direction, i.e., oriented transversely with respect to the ambient compressive stress direction of the Indian shield, assume significance in understanding the seismicity of the region.

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Heterogeneity in crustal structure across the Southern Granulite Terrain (SGT): Inferences from an analysis of gravity and magnetic fields in the Periyar plateau and adjoining areas

Cited by 8 publications

References 13 publications

The Cambrian collisional suture of Gondwana in southern India: A geophysical appraisal

The Cambrian collisional suture of Gondwana in southern India: A geophysical appraisal

Crustal structure and rift tectonics across the Cauvery–Palar basin, Eastern Continental Margin of India based on seismic and potential field modelling

Some Insights into the Lithospheric Electrical Structure in the Western Ghat Region from Magnetotelluric Studies

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