High-temperature metamorphic imprint on calc-silicate granulites of Rayagada, Eastern Ghats, India

Implication for the isobaric cooling path

Rajib Shaw, M. Arima

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Calc-silicate granulites from Rayagada, north-central sector of Eastern Ghats granulite belt show a wide range of mineral assemblages and chemical compositions, which can be grouped as Gr. I (grossular-rich garnet-wollastonite-scapolite-calcite-clinopyroxene), Gr. II (andradite-rich garnet-scapolite-calcite-clinopyroxene), and Gr. III (scapolite-calcite-clinopyroxeneplagioclase) assemblages. Petrographic features suggest the following several reactions in the CaO-Al2O3 - SiO2-vapor system: Mei + 4Wo + Cal = 3Grs + Qtz + 2CO2, Mei + 3Wo + 2Cal = 3Grs + CO2, Mei = 3An + Cal, Wo + CO2 = Cal + Qtz, Mei + 5Wo = 3Grs + 2Qtz + CO2, An + Wo = Grs + Qtz, Mei + 5Cal + 3Qtz = 3Grs + 6CO2, and the following reactions in the CaO-FeO-MgO-Al2O3-SiO2-vapor system: Cpxss + Scp + Wo = Grtss + Qtz + CO2, 4Hd + 2Cal + O2 = 2Adr + 2Qtz + 2CO2, Cpxss + Scp = Grtss + Cal + Qtz. These reactions have been used to estimate peak T-XCO2 condition for these granulites. A maximum temperature of ∼920°C has been calculated at an estimated pressure of 9 kbar. A T-XCO2 diagram shows an isobaric cooling from ∼920°C to ∼815°C. A range of XCO2 (0.50 at 920°C to 0.25 at 815°C) has been observed for Gr. I calc-silicate granulites based on the reaction sequences including coronal garnet-forming reactions. This sequence is suggestive of internal fluid buffering rather than external fluid influx and the differences in XCO2 conditions has been thought to be due to local buffering of fluid phases. Group II and Gr. III calc-silicate granulites, on the other hand, exhibit relatively lower temperature conditions.

Original languageEnglish
Pages (from-to)169-180
Number of pages12
JournalContributions to Mineralogy and Petrology
Volume126
Issue number1-2
Publication statusPublished - 1997
Externally publishedYes

Fingerprint

scapolite
Silicates
Calcium Carbonate
Garnets
India
silicates
garnet
calcite
silicate
Cooling
buffering
cooling
clinopyroxene
Fluids
fluid
garnets
Vapors
andradite
wollastonite
grossular

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

@article{21e7ae6a24df42bb9d16023e219efdf5,
title = "High-temperature metamorphic imprint on calc-silicate granulites of Rayagada, Eastern Ghats, India: Implication for the isobaric cooling path",
abstract = "Calc-silicate granulites from Rayagada, north-central sector of Eastern Ghats granulite belt show a wide range of mineral assemblages and chemical compositions, which can be grouped as Gr. I (grossular-rich garnet-wollastonite-scapolite-calcite-clinopyroxene), Gr. II (andradite-rich garnet-scapolite-calcite-clinopyroxene), and Gr. III (scapolite-calcite-clinopyroxeneplagioclase) assemblages. Petrographic features suggest the following several reactions in the CaO-Al2O3 - SiO2-vapor system: Mei + 4Wo + Cal = 3Grs + Qtz + 2CO2, Mei + 3Wo + 2Cal = 3Grs + CO2, Mei = 3An + Cal, Wo + CO2 = Cal + Qtz, Mei + 5Wo = 3Grs + 2Qtz + CO2, An + Wo = Grs + Qtz, Mei + 5Cal + 3Qtz = 3Grs + 6CO2, and the following reactions in the CaO-FeO-MgO-Al2O3-SiO2-vapor system: Cpxss + Scp + Wo = Grtss + Qtz + CO2, 4Hd + 2Cal + O2 = 2Adr + 2Qtz + 2CO2, Cpxss + Scp = Grtss + Cal + Qtz. These reactions have been used to estimate peak T-XCO2 condition for these granulites. A maximum temperature of ∼920°C has been calculated at an estimated pressure of 9 kbar. A T-XCO2 diagram shows an isobaric cooling from ∼920°C to ∼815°C. A range of XCO2 (0.50 at 920°C to 0.25 at 815°C) has been observed for Gr. I calc-silicate granulites based on the reaction sequences including coronal garnet-forming reactions. This sequence is suggestive of internal fluid buffering rather than external fluid influx and the differences in XCO2 conditions has been thought to be due to local buffering of fluid phases. Group II and Gr. III calc-silicate granulites, on the other hand, exhibit relatively lower temperature conditions.",
author = "Rajib Shaw and M. Arima",
year = "1997",
language = "English",
volume = "126",
pages = "169--180",
journal = "Contributions to Mineralogy and Petrology",
issn = "0010-7999",
publisher = "Springer Verlag",
number = "1-2",

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T1 - High-temperature metamorphic imprint on calc-silicate granulites of Rayagada, Eastern Ghats, India

T2 - Implication for the isobaric cooling path

AU - Shaw, Rajib

AU - Arima, M.

PY - 1997

Y1 - 1997

N2 - Calc-silicate granulites from Rayagada, north-central sector of Eastern Ghats granulite belt show a wide range of mineral assemblages and chemical compositions, which can be grouped as Gr. I (grossular-rich garnet-wollastonite-scapolite-calcite-clinopyroxene), Gr. II (andradite-rich garnet-scapolite-calcite-clinopyroxene), and Gr. III (scapolite-calcite-clinopyroxeneplagioclase) assemblages. Petrographic features suggest the following several reactions in the CaO-Al2O3 - SiO2-vapor system: Mei + 4Wo + Cal = 3Grs + Qtz + 2CO2, Mei + 3Wo + 2Cal = 3Grs + CO2, Mei = 3An + Cal, Wo + CO2 = Cal + Qtz, Mei + 5Wo = 3Grs + 2Qtz + CO2, An + Wo = Grs + Qtz, Mei + 5Cal + 3Qtz = 3Grs + 6CO2, and the following reactions in the CaO-FeO-MgO-Al2O3-SiO2-vapor system: Cpxss + Scp + Wo = Grtss + Qtz + CO2, 4Hd + 2Cal + O2 = 2Adr + 2Qtz + 2CO2, Cpxss + Scp = Grtss + Cal + Qtz. These reactions have been used to estimate peak T-XCO2 condition for these granulites. A maximum temperature of ∼920°C has been calculated at an estimated pressure of 9 kbar. A T-XCO2 diagram shows an isobaric cooling from ∼920°C to ∼815°C. A range of XCO2 (0.50 at 920°C to 0.25 at 815°C) has been observed for Gr. I calc-silicate granulites based on the reaction sequences including coronal garnet-forming reactions. This sequence is suggestive of internal fluid buffering rather than external fluid influx and the differences in XCO2 conditions has been thought to be due to local buffering of fluid phases. Group II and Gr. III calc-silicate granulites, on the other hand, exhibit relatively lower temperature conditions.

AB - Calc-silicate granulites from Rayagada, north-central sector of Eastern Ghats granulite belt show a wide range of mineral assemblages and chemical compositions, which can be grouped as Gr. I (grossular-rich garnet-wollastonite-scapolite-calcite-clinopyroxene), Gr. II (andradite-rich garnet-scapolite-calcite-clinopyroxene), and Gr. III (scapolite-calcite-clinopyroxeneplagioclase) assemblages. Petrographic features suggest the following several reactions in the CaO-Al2O3 - SiO2-vapor system: Mei + 4Wo + Cal = 3Grs + Qtz + 2CO2, Mei + 3Wo + 2Cal = 3Grs + CO2, Mei = 3An + Cal, Wo + CO2 = Cal + Qtz, Mei + 5Wo = 3Grs + 2Qtz + CO2, An + Wo = Grs + Qtz, Mei + 5Cal + 3Qtz = 3Grs + 6CO2, and the following reactions in the CaO-FeO-MgO-Al2O3-SiO2-vapor system: Cpxss + Scp + Wo = Grtss + Qtz + CO2, 4Hd + 2Cal + O2 = 2Adr + 2Qtz + 2CO2, Cpxss + Scp = Grtss + Cal + Qtz. These reactions have been used to estimate peak T-XCO2 condition for these granulites. A maximum temperature of ∼920°C has been calculated at an estimated pressure of 9 kbar. A T-XCO2 diagram shows an isobaric cooling from ∼920°C to ∼815°C. A range of XCO2 (0.50 at 920°C to 0.25 at 815°C) has been observed for Gr. I calc-silicate granulites based on the reaction sequences including coronal garnet-forming reactions. This sequence is suggestive of internal fluid buffering rather than external fluid influx and the differences in XCO2 conditions has been thought to be due to local buffering of fluid phases. Group II and Gr. III calc-silicate granulites, on the other hand, exhibit relatively lower temperature conditions.

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