Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India
International audience Migmatitic cordierite gneisses within the Achankovil Zone (AZ) of southern Pan-African India record melt-producing and subsequent melt-consuming mineral reactions. Early mineral assemblages Bt-Sil-Qtz and Bt-Sil-Spl, deduced from inclusion textures in garnet prophyroblasts, br...
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ftccsdartic:oai:HAL:hal-04404304v1 2024-02-27T08:35:22+00:00 Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India Cenki, B. Kriegsman, L. Braun, I. Géosciences Montpellier Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Université de Montpellier (UM) National Museum of Natural History - Leiden Universität Bonn = University of Bonn 2002-07-29 https://hal.science/hal-04404304 https://doi.org/10.1046/J.1525-1314.2002.00388.X en eng HAL CCSD Wiley-Blackwell info:eu-repo/semantics/altIdentifier/doi/10.1046/J.1525-1314.2002.00388.X hal-04404304 https://hal.science/hal-04404304 doi:10.1046/J.1525-1314.2002.00388.X ISSN: 0263-4929 EISSN: 1525-1314 Journal of Metamorphic Geology https://hal.science/hal-04404304 Journal of Metamorphic Geology, 2002, 20 (6), pp.543-561. ⟨10.1046/J.1525-1314.2002.00388.X⟩ anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/article Journal articles 2002 ftccsdartic https://doi.org/10.1046/J.1525-1314.2002.00388.X 2024-01-28T00:04:40Z International audience Migmatitic cordierite gneisses within the Achankovil Zone (AZ) of southern Pan-African India record melt-producing and subsequent melt-consuming mineral reactions. Early mineral assemblages Bt-Sil-Qtz and Bt-Sil-Spl, deduced from inclusion textures in garnet prophyroblasts, break down via successive dehydration melting reactions to high-T phase assemblages (e.g. Grt-Crd-Liq, Opx-Liq, Spl-Crd-Liq). Later back reactions between the restite and the in situ crystallizing melt resulted in thin cordierite coronas separating garnet from the leucosome, and partial resorption of garnet to Opx-Crd or Crd-Bt-Qtz symplectites. Leucosomes generally display a moderate (low-strain gneisses) to strong (highstrain gneisses) depletion of alkali feldspar attributed to mineral-melt back reactions partly controlled by the degree of melt segregation. Using a KFMASH partial petrogenetic grid that includes a melt phase, and qualitative pseudosections for microdomains of high and low Al ⁄ Si ratios, the successive phase assemblages and reaction textures are interpreted in terms of a clockwise P-T path culminating at about 6-7 kbar and 900-950 °C. This P-T path is consistent with, but more detailed than published results, which suggests that taking a melt phase into account is not only a valid, but also a useful approach. Comparing P-T data and lithological and isotopic data for the AZ with adjacent East Gondwana fragments, suggests the presence of a coherent metasedimentary unit exposed from southern Madagascar via South India (AZ) and Sri Lanka (Wanni Complex) to the Lu¨tzow-Holm Bay in Eastern Antarctica. Article in Journal/Newspaper Antarc* Antarctica Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Journal of Metamorphic Geology 20 6 543 561 |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Cenki, B. Kriegsman, L. Braun, I. Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India |
topic_facet |
anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India anatectic migmatites cordierite gneisses dehydration melting Gondwana KFMASH petrogenetic grid South India [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Migmatitic cordierite gneisses within the Achankovil Zone (AZ) of southern Pan-African India record melt-producing and subsequent melt-consuming mineral reactions. Early mineral assemblages Bt-Sil-Qtz and Bt-Sil-Spl, deduced from inclusion textures in garnet prophyroblasts, break down via successive dehydration melting reactions to high-T phase assemblages (e.g. Grt-Crd-Liq, Opx-Liq, Spl-Crd-Liq). Later back reactions between the restite and the in situ crystallizing melt resulted in thin cordierite coronas separating garnet from the leucosome, and partial resorption of garnet to Opx-Crd or Crd-Bt-Qtz symplectites. Leucosomes generally display a moderate (low-strain gneisses) to strong (highstrain gneisses) depletion of alkali feldspar attributed to mineral-melt back reactions partly controlled by the degree of melt segregation. Using a KFMASH partial petrogenetic grid that includes a melt phase, and qualitative pseudosections for microdomains of high and low Al ⁄ Si ratios, the successive phase assemblages and reaction textures are interpreted in terms of a clockwise P-T path culminating at about 6-7 kbar and 900-950 °C. This P-T path is consistent with, but more detailed than published results, which suggests that taking a melt phase into account is not only a valid, but also a useful approach. Comparing P-T data and lithological and isotopic data for the AZ with adjacent East Gondwana fragments, suggests the presence of a coherent metasedimentary unit exposed from southern Madagascar via South India (AZ) and Sri Lanka (Wanni Complex) to the Lu¨tzow-Holm Bay in Eastern Antarctica. |
author2 |
Géosciences Montpellier Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA)-Université de Montpellier (UM) National Museum of Natural History - Leiden Universität Bonn = University of Bonn |
format |
Article in Journal/Newspaper |
author |
Cenki, B. Kriegsman, L. Braun, I. |
author_facet |
Cenki, B. Kriegsman, L. Braun, I. |
author_sort |
Cenki, B. |
title |
Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India |
title_short |
Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India |
title_full |
Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India |
title_fullStr |
Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India |
title_full_unstemmed |
Melt-producing and melt-consuming reactions in the Achankovil cordierite gneisses, South India |
title_sort |
melt-producing and melt-consuming reactions in the achankovil cordierite gneisses, south india |
publisher |
HAL CCSD |
publishDate |
2002 |
url |
https://hal.science/hal-04404304 https://doi.org/10.1046/J.1525-1314.2002.00388.X |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
ISSN: 0263-4929 EISSN: 1525-1314 Journal of Metamorphic Geology https://hal.science/hal-04404304 Journal of Metamorphic Geology, 2002, 20 (6), pp.543-561. ⟨10.1046/J.1525-1314.2002.00388.X⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1046/J.1525-1314.2002.00388.X hal-04404304 https://hal.science/hal-04404304 doi:10.1046/J.1525-1314.2002.00388.X |
op_doi |
https://doi.org/10.1046/J.1525-1314.2002.00388.X |
container_title |
Journal of Metamorphic Geology |
container_volume |
20 |
container_issue |
6 |
container_start_page |
543 |
op_container_end_page |
561 |
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1792041897681747968 |