Metamorphic P-T Conditions of the Kerala (South India) Khondalite Belt, a Granulite Facies Supracrustal Terrain

Chacko, Thomas; Kumar, G. R. Ravindra; Newton, Robert C.

doi:10.1086/629134

Cited by 161 publications

(61 citation statements)

References 31 publications

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“…Chacko et al, 1987) and cordierite bearing metapelites (e.g. Santosh, 1987) also identified P T paths characterized by isothermal decompression.…”

Section: Discussionmentioning

confidence: 98%

“…The southern part of the high grade metamorphic terrain of South India comprises a vast supracrustal belt termed as the Kerala Khondalite Belt (KKB Chacko et al, 1987; also termed as Trivandrum Granulite Block or TGB Santosh, 1996) (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…The TGB has been the focus of various geological, petrological, isotopic and geochronological investigations for nearly two decades (e.g., Srikantappa et al, 1985;Chacko et al, 1987;Santosh, 1987, Santosh et al, 1990Jackson and Santosh, 1992;Raith and Srikantappa, 1993;Harley and Santosh, 1995;Braun et al, 1996;Nandakumar and Harley, 2000;Cenki et al, 2002;Fonarev et al, 2003). Among these, some studies have also proposed the possible high temperature history of the terrane (e.g., Braun et al, 1996;Chacko et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

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Spinel+Quartz association from the Kerala khondalites, southern India: evidence for ultrahigh-temperature metamorphism

Morimoto

Santosh

Tsunogae

et al. 2004

Journal of Mineralogical and Petrological Sciences

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Granulite facies metapelites (khondalites) from Chittikara are characterized by the assemblage Grt + Sil + Bt + Crd + Spl + Kfs + Pl + Qtz ± graphite. The rocks show a series of mineral reactions such as: (1) Bt + Sil + Qtz = Grt + Crd ± Kfs, (2) Grt + Sil + Qtz = Crd, (3) Grt + Crd + Sil = Spl + Qtz , (4) Spl + Qtz = Crd, and (5) Grt + Sil = Spl + Crd. Spinel and quartz occur in direct grain contact and their stability considerations in appropriate reaction grids indicate > 950°C at 8 kbar. This, together with the ca. 1000°C temperatures derived from mesoperthites suggests ultrahigh temperature metamorphism in the khondalite belt. Electron microprobe data on the various minerals have been used to compute pressure temperature estimates from mineral phase equilibria thermobaromtery. Temperature estimates from spinel cordierite thermometry are around 900°C, while garnet cordierite thermometer yields an upper estimate of 818°C. Estimates based on garnet sillimanite plagioclase quartz barometer indicate pressures up to 8 kbar. Evaluation of the microstructures and reactions in the khondalites using available reaction grids for pelitic rocks provide evidence for peak metamorphism at high or ultrahigh temperatures followed by steep decompression from around 8 kbar down to 4 kbar. The P T path attests to a rapid exhumation history probably associated with the extensional collapse following collision of continental blocks during the assembly of Gondwana in the late Pan African.

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“…Chacko et al, 1987) and cordierite bearing metapelites (e.g. Santosh, 1987) also identified P T paths characterized by isothermal decompression.…”

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spinel+Quartz association from the Kerala khondalites, southern India: evidence for ultrahigh-temperature metamorphism

Morimoto

Santosh

Tsunogae

et al. 2004

Journal of Mineralogical and Petrological Sciences

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“…The Trivandrum Granulite Block (TGB) in the southern part of this terrane consists dominantly of garnet -sillimanite -bearing pelitic granulite (khondalite), quartzo -feldspathic garnet -biotite gneiss (leptynite), charnockite, and subordinate bands and lenses of pyroxene granulite and calc -silicate rocks. Previous petrological studies suggest that the block has been subjected to ultrahigh -temperature (UHT) peak metamorphism at ~ 950 °C and ~ 8 kbar (Chacko et al, 1996;Nandakumar and Harley, 2000;Satish -Kumar et al, 2002;Morimoto et al, 2004) followed by isothermal decompression along a clockwise P -T trajectory (Chacko et al, 1987). Such P -T conditions were, however, mostly derived from the western part of the TGB (wTGB) in Kerala state, and detailed petrologic and geotheromobarometric studies on granulites from the eastern part of the TGB (eTGB) are scarce.…”

Section: Introductionmentioning

confidence: 99%

Metamorphic P-T path of the eastern Trivandrum Granulite Block, southern India: implications for regional correlation of lower crustal fragments

Tadokoro

Tsunogae

Santosh

2008

Journal of Mineralogical and Petrological Sciences

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We report here the metamorphic P -T path for granulite -facies metapelites from the eastern part of the Trivandrum Granulite Block (TGB), southern India, and compare with the paths from the western part of the block as well as from other granulite blocks and shear zones in this region for understanding of exhumation history of the southern granulite terrane. The peak temperature condition of the eastern part (900 -1000 °C) is almost consistent with that from the western part, suggesting regional ultrahigh -temperature (UHT) metamorphism throughout the TGB. However, there is a slight difference in peak pressure conditions between the eastern part (12 kbar) and the western part (10 kbar) estimated from different Zn content within spinel in equilibrium with quartz. Such P ~ 12 kbar high -pressure event is consistent with that obtained from granulite -facies rocks further north in the Palghat -Cauvery Shear Zone system (PCSZ) and Madurai Granulite Block (MGB). The results therefore suggest that the TGB, MGB, and PCSZ underwent similar prograde high -pressure metamorphism followed by peak UHT event along a clockwise P -T trajectory, related to the collisional orogeny during the assembly of the Gondwana Supercontinent.

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“…These plutons are emplaced at the north ern (CR) and southern (PU) margin of a wide granulite facies supracrustal belt known as the Kerala Khondalite Belt (KKB; Chacko et al, 1987). The aluminous metapelites in this region are characterized by 8180 values of ca.…”

Section: Resultsmentioning

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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Metamorphic P-T Conditions of the Kerala (South India) Khondalite Belt, a Granulite Facies Supracrustal Terrain

Cited by 161 publications

References 31 publications

Spinel+Quartz association from the Kerala khondalites, southern India: evidence for ultrahigh-temperature metamorphism

Spinel+Quartz association from the Kerala khondalites, southern India: evidence for ultrahigh-temperature metamorphism

Metamorphic P-T path of the eastern Trivandrum Granulite Block, southern India: implications for regional correlation of lower crustal fragments

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

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