Melt‐producing and melt‐consuming reactions in the Achankovil cordierite gneisses, South India
Abstract 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 s...
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crwiley:10.1046/j.1525-1314.2002.00388.x 2024-09-15T17:45:58+00:00 Melt‐producing and melt‐consuming reactions in the Achankovil cordierite gneisses, South India Cenki, B. Kriegsman, L. M. Braun, I. 2002 http://dx.doi.org/10.1046/j.1525-1314.2002.00388.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1525-1314.2002.00388.x https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1525-1314.2002.00388.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Metamorphic Geology volume 20, issue 6, page 543-561 ISSN 0263-4929 1525-1314 journal-article 2002 crwiley https://doi.org/10.1046/j.1525-1314.2002.00388.x 2024-08-13T04:15:55Z Abstract 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 (high‐strain 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 Lützow–Holm Bay in Eastern Antarctica. Article in Journal/Newspaper Antarc* Antarctica Wiley Online Library Journal of Metamorphic Geology 20 6 543 561 |
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English |
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Abstract 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 (high‐strain 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 Lützow–Holm Bay in Eastern Antarctica. |
format |
Article in Journal/Newspaper |
author |
Cenki, B. Kriegsman, L. M. Braun, I. |
spellingShingle |
Cenki, B. Kriegsman, L. M. Braun, I. Melt‐producing and melt‐consuming reactions in the Achankovil cordierite gneisses, South India |
author_facet |
Cenki, B. Kriegsman, L. M. 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 |
Wiley |
publishDate |
2002 |
url |
http://dx.doi.org/10.1046/j.1525-1314.2002.00388.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1525-1314.2002.00388.x https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1525-1314.2002.00388.x |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Journal of Metamorphic Geology volume 20, issue 6, page 543-561 ISSN 0263-4929 1525-1314 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1046/j.1525-1314.2002.00388.x |
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Journal of Metamorphic Geology |
container_volume |
20 |
container_issue |
6 |
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543 |
op_container_end_page |
561 |
_version_ |
1810493903061647360 |