Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India
Incipient charnockites have been widely used as evidence for the infiltration of CO2-rich fluids driving dehydration of the lower crust. Rocks exposed at Kakkod quarry in the Trivandrum Block of southern India allow for a thorough investigation of the metamorphic evolution by preserving not only ort...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
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Wiley - Blackwell
2016
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| Online Access: | http://purl.org/au-research/grants/arc/DP150102773 http://hdl.handle.net/20.500.11937/47078 |
| _version_ | 1848757735585218560 |
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| author | Blereau, E. Clark, Christopher Taylor, Richard Johnson, Tim Fitzsimons, Ian Santosh, M. |
| author_facet | Blereau, E. Clark, Christopher Taylor, Richard Johnson, Tim Fitzsimons, Ian Santosh, M. |
| author_sort | Blereau, E. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Incipient charnockites have been widely used as evidence for the infiltration of CO2-rich fluids driving dehydration of the lower crust. Rocks exposed at Kakkod quarry in the Trivandrum Block of southern India allow for a thorough investigation of the metamorphic evolution by preserving not only orthopyroxene-bearing charnockite patches in a host garnet-biotite felsic gneiss, but also layers of garnet-sillimanite metapelite gneiss. Thermodynamic phase equilibria modelling of all three bulk compositions indicates consistent peak-metamorphic conditions of 830-925 °C and 6-9 kbar with retrograde evolution involving suprasolidus decompression at high temperature. These models suggest that orthopyroxene was most likely stabilized close to the metamorphic peak as a result of small compositional heterogeneities in the host garnet-biotite gneiss. There is insufficient evidence to determine whether the heterogeneities were inherited from the protolith or introduced during syn-metamorphic fluid flow. U-Pb geochronology of monazite and zircon from all three rock types constrains the peak of metamorphism and orthopyroxene growth to have occurred between the onset of high-grade metamorphism at c. 590 Ma and the onset of melt crystallization at c. 540 Ma. The majority of metamorphic zircon growth occurred during protracted melt crystallization between c. 540 and 510 Ma. Melt crystallization was followed by the influx of aqueous, alkali-rich fluids likely derived from melts crystallizing at depth. This late fluid flow led to retrogression of orthopyroxene, the observed outcrop pattern and to the textural and isotopic modification of monazite grains at c. 525-490 Ma. |
| first_indexed | 2025-11-14T09:32:49Z |
| format | Journal Article |
| id | curtin-20.500.11937-47078 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:32:49Z |
| publishDate | 2016 |
| publisher | Wiley - Blackwell |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-470782022-10-12T07:19:50Z Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India Blereau, E. Clark, Christopher Taylor, Richard Johnson, Tim Fitzsimons, Ian Santosh, M. Incipient charnockites have been widely used as evidence for the infiltration of CO2-rich fluids driving dehydration of the lower crust. Rocks exposed at Kakkod quarry in the Trivandrum Block of southern India allow for a thorough investigation of the metamorphic evolution by preserving not only orthopyroxene-bearing charnockite patches in a host garnet-biotite felsic gneiss, but also layers of garnet-sillimanite metapelite gneiss. Thermodynamic phase equilibria modelling of all three bulk compositions indicates consistent peak-metamorphic conditions of 830-925 °C and 6-9 kbar with retrograde evolution involving suprasolidus decompression at high temperature. These models suggest that orthopyroxene was most likely stabilized close to the metamorphic peak as a result of small compositional heterogeneities in the host garnet-biotite gneiss. There is insufficient evidence to determine whether the heterogeneities were inherited from the protolith or introduced during syn-metamorphic fluid flow. U-Pb geochronology of monazite and zircon from all three rock types constrains the peak of metamorphism and orthopyroxene growth to have occurred between the onset of high-grade metamorphism at c. 590 Ma and the onset of melt crystallization at c. 540 Ma. The majority of metamorphic zircon growth occurred during protracted melt crystallization between c. 540 and 510 Ma. Melt crystallization was followed by the influx of aqueous, alkali-rich fluids likely derived from melts crystallizing at depth. This late fluid flow led to retrogression of orthopyroxene, the observed outcrop pattern and to the textural and isotopic modification of monazite grains at c. 525-490 Ma. 2016 Journal Article http://hdl.handle.net/20.500.11937/47078 10.1111/jmg.12192 http://purl.org/au-research/grants/arc/DP150102773 Wiley - Blackwell fulltext |
| spellingShingle | Blereau, E. Clark, Christopher Taylor, Richard Johnson, Tim Fitzsimons, Ian Santosh, M. Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India |
| title | Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India |
| title_full | Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India |
| title_fullStr | Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India |
| title_full_unstemmed | Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India |
| title_short | Constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the Trivandrum Block, southern India |
| title_sort | constraints on the timing and conditions of high-grade metamorphism, charnockite formation and fluid-rock interaction in the trivandrum block, southern india |
| url | http://purl.org/au-research/grants/arc/DP150102773 http://hdl.handle.net/20.500.11937/47078 |