Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India
Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure–temperature–time (P–T–t) evolution of the Nagercoil Block at the southernmost tip of peninsular India. An inferred peak metamorphic assemblage of garnet, K-feldspar, sillimanite, plagi...
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Elsevier
2015-05-01
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| Series: | Geoscience Frontiers |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987114001601 |
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| author | Tim E. Johnson Chris Clark Richard J.M. Taylor M. Santosh Alan S. Collins |
| author_facet | Tim E. Johnson Chris Clark Richard J.M. Taylor M. Santosh Alan S. Collins |
| author_sort | Tim E. Johnson |
| collection | DOAJ |
| description | Data from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure–temperature–time (P–T–t) evolution of the Nagercoil Block at the southernmost tip of peninsular India. An inferred peak metamorphic assemblage of garnet, K-feldspar, sillimanite, plagioclase, magnetite, ilmenite, spinel and melt is consistent with peak metamorphic pressures of 6–8 kbar and temperatures in excess of 900 °C. Subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 °C. SHRIMP U–Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palaeoproterozoic crystallisation ages. New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation, and the minimum age of the metamorphic peak, to around 560 Ma. The data suggest two stages of monazite growth. The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite. Relatively REE-depleted rims, which have a pronounced negative europium anomaly, grew during melt crystallisation along the retrograde path at around 535 Ma. Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer, supporting a long-lived high-grade metamorphic history. The metamorphic conditions, timing and duration of the implied clockwise P–T–t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent. |
| first_indexed | 2024-03-12T10:42:22Z |
| format | Article |
| id | doaj.art-1ece39830cd1414ba13a8b64f3b2a713 |
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| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T10:42:22Z |
| publishDate | 2015-05-01 |
| publisher | Elsevier |
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| series | Geoscience Frontiers |
| spelling | doaj.art-1ece39830cd1414ba13a8b64f3b2a7132023-09-02T07:58:42ZengElsevierGeoscience Frontiers1674-98712015-05-016337338710.1016/j.gsf.2014.12.003Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern IndiaTim E. Johnson0Chris Clark1Richard J.M. Taylor2M. Santosh3Alan S. Collins4Department of Applied Geology, The Institute for Geoscience Research (TIGeR), Curtin University, GPO Box U1987, Perth, WA 6845, AustraliaDepartment of Applied Geology, The Institute for Geoscience Research (TIGeR), Curtin University, GPO Box U1987, Perth, WA 6845, AustraliaDepartment of Applied Geology, The Institute for Geoscience Research (TIGeR), Curtin University, GPO Box U1987, Perth, WA 6845, AustraliaSchool of the Earth Sciences and Resources, China University of Geosciences (Beijing), 29 Xueyuan Road, Beijing 100083, ChinaTectonics, Resources and Exploration (TRaX), Department of Earth Sciences, University of Adelaide, SA 5005, AustraliaData from a migmatised metapelite raft enclosed within charnockite provide quantitative constraints on the pressure–temperature–time (P–T–t) evolution of the Nagercoil Block at the southernmost tip of peninsular India. An inferred peak metamorphic assemblage of garnet, K-feldspar, sillimanite, plagioclase, magnetite, ilmenite, spinel and melt is consistent with peak metamorphic pressures of 6–8 kbar and temperatures in excess of 900 °C. Subsequent growth of cordierite and biotite record high-temperature retrograde decompression to around 5 kbar and 800 °C. SHRIMP U–Pb dating of magmatic zircon cores suggests that the sedimentary protoliths were in part derived from felsic igneous rocks with Palaeoproterozoic crystallisation ages. New growth of metamorphic zircon on the rims of detrital grains constrains the onset of melt crystallisation, and the minimum age of the metamorphic peak, to around 560 Ma. The data suggest two stages of monazite growth. The first generation of REE-enriched monazite grew during partial melting along the prograde path at around 570 Ma via the incongruent breakdown of apatite. Relatively REE-depleted rims, which have a pronounced negative europium anomaly, grew during melt crystallisation along the retrograde path at around 535 Ma. Our data show the rocks remained at suprasolidus temperatures for at least 35 million years and probably much longer, supporting a long-lived high-grade metamorphic history. The metamorphic conditions, timing and duration of the implied clockwise P–T–t path are similar to that previously established for other regions in peninsular India during the Ediacaran to Cambrian assembly of that part of the Gondwanan supercontinent.http://www.sciencedirect.com/science/article/pii/S1674987114001601MonaziteMigmatiteZirconGeochronologyPhase equilibria modellingGondwana |
| spellingShingle | Tim E. Johnson Chris Clark Richard J.M. Taylor M. Santosh Alan S. Collins Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India Geoscience Frontiers Monazite Migmatite Zircon Geochronology Phase equilibria modelling Gondwana |
| title | Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India |
| title_full | Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India |
| title_fullStr | Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India |
| title_full_unstemmed | Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India |
| title_short | Prograde and retrograde growth of monazite in migmatites: An example from the Nagercoil Block, southern India |
| title_sort | prograde and retrograde growth of monazite in migmatites an example from the nagercoil block southern india |
| topic | Monazite Migmatite Zircon Geochronology Phase equilibria modelling Gondwana |
| url | http://www.sciencedirect.com/science/article/pii/S1674987114001601 |
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