Precambrian Tectonics and Crustal Evolution in South India

Drury, S. A.; Harris, Nigel; Holt, R. W.; Reeves-Smith, G. J.; Wightman, R. T.

doi:10.1086/628831

Cited by 452 publications

(241 citation statements)

References 37 publications

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“…They are flat E-W trending linear bodies showing sub-parallelism to the trend of main shear (Satyanarayanan et al 2011).The movement in the BSZ is thus in the nature of obliqueslip with the dip-slip component dominant. Folding and flattening of enclaves in the host-rock reflects increased viscosity of all intrusive phases during NE-SW shortening (Drury et al 1984). BSZ straight margins also suggest a rigid host, which is emphasized further by still later narrow conjugate offsets.…”

Section: F)mentioning

confidence: 93%

Metamorphism and deformation of mafic and felsic rocks in Bhavani Shear Zone, Tamilnadu, India

Prian

Singh²,

Kumar³

et al. 2014

International Journal of Advanced Geosciences

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In southern India, Nilgiri block (NB) is separated from Western Dharwar Craton (WDC) and Palghat Cauvery Shear Zone (PCSZ) by Moyar and Bhavani shear zone (MSZ and BSZ) respectively. The Archaean high grade Bhavani shear is composed predominantly of meta-gabbro, meta-anorthosite and garnetiferrous gabbro, along with pyroxenite and amphibolites. The mafic rocks associated with hornblende gabbro and pyroxenite, retain magmatic structures and show evidence of major change in grain size and shapes granofelses of igneous relicts. The BSZ and MSZ are steeply-dipping thrusts, the Moyar shear in predominantly dip-slip transport. Gabbro majorly consists, assemblage of almandine-pyrope garnet and augite clinopyroxene as phenocryst with coexisting porphyroblasts texture. Geological structure relations combined with petrographical analysis from Moyar Bhavani shear zone (MBSZ) suggest that the gabbroic metamorphism was related to formation of the shear zone. Intermingled gabbroic rocks escaped metamorphism because they remained magmatic to lower temperatures, and experienced shorter and lower temperature sub-solidus cooling intervals. The felsic rocks underwent relatively high temperature solid-state deformation, as indicated by gabbro replacing K-felspar and subgrain patterns in quartz. The felsic rocks were deformed in the solid state because of their high proportion of relatively weak minerals (quartz and biotite), whereas, the mafic rocks mostly escaped sub-solidus deformation, except in local high-strain zone of their high proportion of relatively (hornblende and plagioclase) strong minerals.

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Section: F)mentioning

confidence: 93%

Metamorphism and deformation of mafic and felsic rocks in Bhavani Shear Zone, Tamilnadu, India

Prian

Singh²,

Kumar³

et al. 2014

International Journal of Advanced Geosciences

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“…The SGT is composed of a variety of granulite blocks that underwent extreme crustal metamorphism during late NeoproterozoicCambrian time and is dissected by major transcrustal shear zones (Drury and Holt, 1980;Drury et al, 1984 and so on). The ACSZ, which appears as a prominent lineament in aeromagnetic and satellite images, trends NW -SE with a width of ~ 15 km and a lateral extension of ~ 120 km (Drury et al, 1984;Guru Rajesh and Chetty, 2006). ACSZ has figured prominently as a deep -rooted shear zone of intercontinental scale in many Gondwana reconstruction models (e.g., Windley et al, 1994 and references therein).…”

Section: Geological Setting and Petrographymentioning

confidence: 99%

“…ACSZ has figured prominently as a deep -rooted shear zone of intercontinental scale in many Gondwana reconstruction models (e.g., Windley et al, 1994 and references therein). It is bounded to the north by the massif charnockites and intercalated high to ultrahigh temperature grade metasediments of the Madurai block (MB), and to the south by high temperature granulite facies supracrustals of the Trivandrum block (TB) (Drury et al, 1984;Bart lett et al, 1998;Shimpo et al, 2006). Rocks in ACSZ are dominated by intensely deformed garnetiferous biotite gneiss, quartzofeldspathic gneiss, cordierite -orthopyroxene gneiss, and charnockite (e.g., Santosh, 1987;Nandakumar and Harley, 2000;Cenki et al, 2004;Ishii et al, 2006).…”

Section: Geological Setting and Petrographymentioning

confidence: 99%

Origin of graphite in glimmerite and spinellite in Achankovil Shear Zone, southern India

Rajesh

Arai

Satish-Kumar

2009

Journal of Mineralogical and Petrological Sciences

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We report occurrence and origin of graphite in glimmerite and spinellite from an unusual ultramafic complex in Achankovil Shear Zone (ACSZ) in southern India. Raman analyses of primary graphite flakes in close association with spinel and phlogopite confirm the highly crystalline nature. The carbon isotope composition ranges from -7‰ to -9.8‰ typical of mantle -derived graphite. A genetic model is proposed in which carbon was derived from a reduced juvenile mantle source linked to the genesis of volatile rich ultramafic rocks in ACSZ.

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“…1. (a) Locations of the on-land and seafloor magnetometer sites superimposed on geology and regional tectonic elements of south India and surrounding sea (after GSI (1993), Drury et al (1984) and Curray and Munasinghe (1991)). Sediment isopachs (km) in Bay of Bengal are given by dotted line (Curray et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

Integrated modeling of EM response functions from Peninsular India and Bay of Bengal

Arora

Rao

2014

Earth Planet Sp

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Existing sets of magnetovariational data from the large numbers of sites distributed across the peninsular India and those in the Bay of Bengal are reanalysed to obtain inter-site vertical and horizontal field transfer functions. Maps of induction arrows relocate the earlier reported conductive zones beneath the Palk-Strait and a regional scale anomaly in the offshore region, immediately southwest of the southern tip of Indian Peninsula, named South India Offshore Conductivity Anomaly (SIOCA). Period dependence of the induction arrows suggests that with increasing period SIOCA tends to control the induction pattern over the entire peninsula. Presentation of the horizontal transfer functions in the form of ellipses of anomalous currents helps to characterize the period and spatial behaviour of horizontal fields at seafloor sites. Integrated thin sheet modeling of the on-land and seafloor induction features suggest that the greater part of the anomalous behaviour of the horizontal fields at seafloor sites can be attributed to the shielding effects due to seawater. The weak anisotropic behaviour of the horizontal fields at selected sites can be explained in terms of the concentration of the induced currents in the sediment filled troughs on either side of the 85• E Ridge. Several lines of geophysical evidence favour the hypothesis that SIOCA, low velocity zone, low magnetization anomaly, all centered near the southern tip of the India, are the relics of the interaction of Marion Plume outburst with Indian lithosphere.

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Precambrian Tectonics and Crustal Evolution in South India

Cited by 452 publications

References 37 publications

Metamorphism and deformation of mafic and felsic rocks in Bhavani Shear Zone, Tamilnadu, India

Metamorphism and deformation of mafic and felsic rocks in Bhavani Shear Zone, Tamilnadu, India

Origin of graphite in glimmerite and spinellite in Achankovil Shear Zone, southern India

Integrated modeling of EM response functions from Peninsular India and Bay of Bengal

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