The Cauvery Shear Zone, Southern Granulite Terrain, India: A crustal-scale flower structure

Chetty, T.R.K.; Rao, Y. J. Bhaskar

doi:10.1016/j.gr.2005.11.017

Cited by 126 publications

(65 citation statements)

References 16 publications

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“…The PCSZ is an E-W trending network of transpressional shears that mark the boundary between the Late Neoproterozoic to Early Cambrian Madurai Block to the south and the Archaean Dharwar Craton to the north (Chetty and Bhaskar Rao, 2006;Santosh et al, 2006aSantosh et al, , 2009aCollins et al, 2007b, Clark et al, 2009a. Sapphirine-, corundum-and gedrite-bearing Mg-Al-rich rocks occur in various localities within the Suture Zone surrounding the Karur and Namakkal districts of Tamil Nadu State.…”

Section: Palghat-cauvery Suture Zonementioning

confidence: 99%

Sapphirine + quartz assemblage from the Southern Granulite Terrane, India: diagnostic evidence for ultrahigh‐temperature metamorphism within the Gondwana collisional orogen

Tsunogae

Santosh

2011

Geological Journal

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A synthesis of the petrological characters of granulite facies rocks that contain equilibrium sapphirine þ quartz assemblage from three localities (Rajapalaiyam, Ganguvarpatti and Panangad) in the Southern Granulite Terrane (SGT), India, provides unequivocal evidence for extreme crustal metamorphism associated with the collisional assembly of the Gondwana supercontinent during the Late Neoproterozoic to Early Cambrian. The reaction microstructures associated with sapphirine þ quartz vary among the samples, probably suggesting different tectonic conditions during the metamorphic evolution. Sapphirine and quartz in pelitic granulites from Rajapalaiyam in the Madurai Block occur as an intergrowth in poikiloblastic garnet, whereas the two minerals show host-inclusion relationship (quartz inclusion in coarse-grained sapphirine) in a Mg-Al-rich rock from Ganguvarpatti in the same block. The sapphirine-quartz association and related microstructures from the two localities are consistent with isobaric cooling from sapphirine þ quartz to orthopyroxene þ sillimanite þ quartz fields, possibly along a counterclockwise P-T path. In contrast, sapphirine þ quartz occurs as coronas around Mg-rich (X Mg $ 0.58) staurolite within poikiloblastic garnet in an Mg-Al-rich rock from Panangad in the Palghat-Cauvery Suture Zone (PCSZ). The texture suggests decompression from the stability field of Mg-rich staurolite (P > 15 kbar) at T > 1000 8C possibly along a clockwise P-T trajectory. Such contrasting P-T paths are consistent with a recent tectonic model of the SGT, according to which the metamorphism in the Madurai Block is related to heat (and fluid) input from the mantle, whereas that in the PCSZ is related to the subduction-collision tectonics between the Madurai Block and the Dharwar Craton, where high-pressure and ultrahigh-temperature (UHT) metamorphic rocks were extruded along the subduction channel.

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Section: Palghat-cauvery Suture Zonementioning

confidence: 99%

Sapphirine + quartz assemblage from the Southern Granulite Terrane, India: diagnostic evidence for ultrahigh‐temperature metamorphism within the Gondwana collisional orogen

Tsunogae

Santosh

2011

Geological Journal

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“…North-south direction is found to be the predominant orientation of very short and short lineaments in addition to NE-SW direction of the later. Moderate-sized lineaments are oriented predominantly geologic time as reported by Anderson (1951), Drury and Holt (1980), Bartlett, Dougherty, Harris, Hawkesworth, and Santosh (1998), Ramasamy et al (1999), Chetty et al (2003), Bhaskar Rao et al (2003, Chetty and Bhaskar Rao (2006) and Tirukumaran (2013). The predominant orientation of the lineaments of the study almost corroborates with the results of several regional studies on lineaments (Balaji, 2010;Rakshit & Prabhakar Rao, 1989;Subramanian & Mani, 1979;Tirukumaran, 2013) and with the orientation of a number of prominent geological This data can serve as a valuable input in evolving strategies towards developmental and management planning of this natural resource-rich hill which is facing threats from anthropogenic activities.…”

Section: Resultsmentioning

confidence: 67%

“…The study area forms part of the geologically well-known southern Granulitic Terrain of Tamil Nadu state which has experienced multiple episodes of crustal deformation (Chetty & Bhaskar Rao, 2006;Chetty, Vijay, Narayana, & Giridhar, 2003;Drury & Holt, 1980;Ramasamy et al, 1999) because of which the rocks are highly deformed and metamorphosed to granulite facies. Geochronological and isotope studies have shown crustal growth of the terrain during the period 3400 Ma.…”

Section: Geology Of the Study Areamentioning

confidence: 99%

Mapping and analysis of tectonic lineaments of Pachamalai hills, Tamil Nadu, India using geospatial technology

Prabhakaran

Raj

2018

Geology, Ecology, and Landscapes

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In the present study an updated tectonic lineament database for Pachamalai hill, a resourcerich hill of central Tamil Nadu state of India has been generated and analysed. Digital Elevation Model generated from CARTOSAT-1 satellite data have been the data source. Lineaments extracted from eight different azimuth angles were compiled together towards the generation of the lineament database, which has been subsequently analysed for their number, length, density and spatial distribution using ArcGIS software. In addition, their orientations were analysed using Rockworks software. Of the 561 lineaments of the study area, about 90% are very short and short lineaments. The total length of the lineaments is 680 sq. km and their density ranges from 0 to 3.4 km/sq. km. The diversely oriented lineaments of the hill reflect the multiple deformation events that have affected the region through geologic time. In about 30% of the hill, the lineament density is high to very high which implies higher degree of deformation, fracturing, shearing and permeability of rocks besides higher soil erodibility and groundwater yield. These high to very high density areas render themselves unsuitable for the construction of dams and reservoirs as the possibility of water leakages into the subsurface, slope and dam failures and rate of sedimentation would be higher. Further, the analysis of the lineaments clearly underlines the need to extract lineaments from different azimuth angles instead of the widely adopted practice of mapping lineaments from single azimuth angle.

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“…It has traditionally been described as a vestigial facet of the Dharwar craton, however, owing its present height to intermittent movements taking place since the Late Mesozoic through Quaternary (RADHAKRISHNA, 1993;VALDIA, 1998). Several orogenic models having different burial and subsequent uplift to deep crustal rocks have been attempted for uplifted high-grade Archaean rocks of the SGT (RADHAKRISHNA, 1969;DRURY et al, 1984;THAKUR and NAGARAJAN, 1992;SRINAGESH and RAI, 1996;CHETTY and BHASKAR RAO, 2006;SANTOSH et al, 2009). On the one hand, these models of the SGT evoke long-lived crustal roots that have remained undisturbed, being imprints of Precambrian tectonism (SRINAGESH and RAI, 1996;GUPTA et al, 2003) and, on the other hand, repeated remobilization in response to seven episodes of thermo-tectonic perturbations at *2.5 Ga, *2.0 Ga, *1.6 Ga, *1.0 Ga, *800 Ma, 600 Ma and *550 Ma, and two distinct episodes of metamorphism at *2.5 Ga and *550 Ma (e.g., RADHAKRISHNA, 1993;VALDIA, 1998;GHOSH et al, 2004).…”

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.

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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.

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The Cauvery Shear Zone, Southern Granulite Terrain, India: A crustal-scale flower structure

Cited by 126 publications

References 16 publications

Sapphirine + quartz assemblage from the Southern Granulite Terrane, India: diagnostic evidence for ultrahigh‐temperature metamorphism within the Gondwana collisional orogen

Sapphirine + quartz assemblage from the Southern Granulite Terrane, India: diagnostic evidence for ultrahigh‐temperature metamorphism within the Gondwana collisional orogen

Mapping and analysis of tectonic lineaments of Pachamalai hills, Tamil Nadu, India using geospatial technology

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

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