Late Precambrian alkaline plutons in southwest India: Geochronologic and rare-earth element constraints on Pan-African magmatism

Santosh, M.; Iyer, Brijesh; Vasconcellos, M. B. A.; Enzweiler, Jacinta

doi:10.1016/0024-4937(89)90016-9

Cited by 66 publications

(28 citation statements)

References 29 publications

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“…Several ages of crystallization or emplacement falling between ∼850 to 730 Ma are reported from the Madurai Block (Santosh et al 1989;Ghosh et al 2004;Pandey et al 2005;Teale et al 2011;Plavsa et al 2012;Brandt et al 2014;George et al 2015). The garnet-bearing granite-charncokite association as reported by George et al (2015) from the Mottamalai hills (Rajapalayam) is similar to what has been studied near Pudukkottai during the present study.…”

Section: Previous Geochronological Studies and Link Between Magmatismsupporting

confidence: 90%

Rb–Sr and Sm–Nd study of granite–charnockite association in the Pudukkottai region and the link between metamorphism and magmatism in the Madurai Block

2016

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Pudukkottai region in the northeastern part of the Madurai Block exposes the garnetiferous pink granite that intruded the biotite gneiss. Charnockite patches are associated with both the rock types. Rb-Sr biotite and Sm-Nd whole-rock isochron ages indicate a regional uplift and cooling at ∼550 Ma. The initial Nd isotope ratios (ε t Nd = −20 to −22) and Nd depleted-mantle model ages (T DM = 2.25 to 2.79 Ga) indicate a common crustal source for the pink-granite and associated charnockite, while the biotite gneiss and the charnockite within it represent an older crustal source (ε t Nd = −29 and T DM = >3.2 Ga). The Rb-Sr whole-rock data and initial Sr-Nd isotope ratios also help demonstrate the partial but systematic equilibration of Sr isotope and Rb/Sr ratios during metamorphic mineral-reactions resulting in an 'apparent whole-rock isochron'. The available geochronological results from the Madurai Block indicate four major periods of magmatism and metamorphism: Neoarchaean-Paleoproterozoic, Mesoproterozoic, mid-Neoproterozoic and late-Neoproterozoic. We suggest that the high-grade and ultrahigh-temperature metamorphism was preceded by magmatism which 'prepared' the residual crust to sustain the high P -T conditions. There also appears to be cyclicity in the tectono-magmatic events and an evolutionary model for the Madurai Block should account for the cyclicity in the preserved records.

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Section: Previous Geochronological Studies and Link Between Magmatismsupporting

confidence: 90%

Rb–Sr and Sm–Nd study of granite–charnockite association in the Pudukkottai region and the link between metamorphism and magmatism in the Madurai Block

2016

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“…1), con sidered as late Proterozoic strike-slip shear systems (Drury et al, 1984). The fact that several of these lineaments have controlled the emplace ment of mafic and ultramafic bodies, including anorthosites, gabbros, dolerites, dunites and in some cases even carbonatites during different timespans in the geologic history (Deans and Powell, 1968) lends support to the notion that these lineaments are indeed deep-seated faults de veloped during the pre-rift tectonics of the In dian continent within the Gondwana ensemble (Santosh et al, 1989). The proximity of the alkali granites and syenites of present study to the edges or junctions of these megafaults of con tinental scale suggests a taphrogenic (rift-con trolled) magmatic regime.…”

mentioning

confidence: 88%

“…Uniform enrichment of high field strength elements (HFSE) in all the plutons, and light rare earth elements (LREE) in some, regardless of the relative modal abun dance of accessory phases like monazite, zircon, titanite and apatite would indicate a primary magmatic character (cf. Santosh et al, 1989). In the general classification scheme of granites to I and S-types, anorogenic alkali granites have been further classified as A-type (Loiselle and Wones, 1979).…”

mentioning

confidence: 99%

Reconnaissance oxygen and sulfur isotopic mapping of Pan-African alkali granites and syenites in the southern Indian Shield.

Santosh

Masuda

1991

Geochem. J.

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“…Geochemical studies have been carried out on the granites of the KKB by several workers (Santosh and Nair 1983;Santosh 1989;Santosh et al 1989;Rajesh 2004;Braun 2006). Braun (2006) has studied the granites within the Achankovil lineament zone, and lecogranites as well as granitic gneisses of the KKB.…”

Section: Radioelement Abundances and Heat Productionmentioning

confidence: 99%

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

Ray

Roy

Srinivasan

2007

Int J Earth Sci (Geol Rundsch)

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In situ radioelemental (K, U and Th) analysis and heat production estimates have been made at 59 sites in the Kerala Khondalite Block (KKB) of the Southern Granulite Province (SGP) of India. Together with the in situ analyses on granulites and gneisses previously reported from 28 sites, and heat production estimated from the published geochemical analyses on granites and syenites of the KKB, the new data set allows good characterization of heat production for the major granulite facies rocks and granitoids of the KKB. Garnet biotite gneisses are characterized by high levels of Th and U, with mean values of 60 and 3 ppm, respectively. Khondalites, leptynites and charnockites have slightly lower levels of Th (23, 20 and 22 ppm, respectively) and U (2.9, 2.4 and 0.9 ppm, respectively). The mean K, U, Th abundances for the granites, leucogranites and granitic gneisses ranges from 3.9 to 4.3%, 2.6 to 4.3 ppm, 22 to 50 ppm respectively, and for the syenites 4.8%, 2 ppm and 5.7 ppm. Mean radiogenic heat production values for garnet-biotite gneiss, khondalite, leptynite and charnockite are 5.5, 2.7, 2.4 and 2.2 lW m -3 , respectively. For the granites, leucogranites, granitic gneisses and syenites it is 2.6, 3.4, 4.6 and 1.4 lW m -3 , respectively. Heat production of granulite facies rocks, which are the most abundant rocks in KKB, correlate well with Th, but less with U, suggesting that variation is caused by Th and U bearing accessory minerals such as monazite and zircon. The high heat production of the KKB granulites are in contrast to the low heat production of the Late Archaean granulites of the Northern Block (NB) of the SGP which are highly depleted in radioelements and also the granulites of Madurai Block (MB) that have higher radioelemental abundances than in the granulites of the NB. The high heat production of the KKB granulites could be due to the nature of protoliths and/or metasomatism associated with Neoproteroic-to-Pan African alkaline magmatic activity represented by alkali granite and syenite-carbonatite emplacements and emplacement of pegmatites.

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Late Precambrian alkaline plutons in southwest India: Geochronologic and rare-earth element constraints on Pan-African magmatism

Cited by 66 publications

References 29 publications

Rb–Sr and Sm–Nd study of granite–charnockite association in the Pudukkottai region and the link between metamorphism and magmatism in the Madurai Block

Rb–Sr and Sm–Nd study of granite–charnockite association in the Pudukkottai region and the link between metamorphism and magmatism in the Madurai Block

Reconnaissance oxygen and sulfur isotopic mapping of Pan-African alkali granites and syenites in the southern Indian Shield.

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

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