P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique
Pan-African high-pressure granulites occur as boudins and layers in the Lurio Belt in north-eastern Mozambique, eastern Africa. Mafic granulites contain the mineral assemblage garnet + clinopyroxene + plagioclase + quartz ± magnesiohastingsite. Garnet porphyroblasts are zoned with increasing almandi...
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ftunibolognairis:oai:cris.unibo.it:11585/567061 2024-09-15T17:45:12+00:00 P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique Engvik, Ane K Tveten, E. Bingen, B. Erambert, M. Feito, P. De Azavedo, S. VIOLA, GIULIO Engvik, Ane K Tveten, E. Bingen, B. Viola, Giulio Erambert, M. Feito, P. De Azavedo, S. 2007 STAMPA http://hdl.handle.net/11585/567061 https://doi.org/10.1111/j.1525-1314.2007.00736.x eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000250943000001 volume:25 issue:9 firstpage:935 lastpage:952 numberofpages:18 journal:JOURNAL OF METAMORPHIC GEOLOGY http://hdl.handle.net/11585/567061 doi:10.1111/j.1525-1314.2007.00736.x info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-36248963663 Corona texture High-pressure granulite Isothermal decompression Lurio Belt Pan-African Geology info:eu-repo/semantics/article 2007 ftunibolognairis https://doi.org/10.1111/j.1525-1314.2007.00736.x 2024-07-08T14:06:46Z Pan-African high-pressure granulites occur as boudins and layers in the Lurio Belt in north-eastern Mozambique, eastern Africa. Mafic granulites contain the mineral assemblage garnet + clinopyroxene + plagioclase + quartz ± magnesiohastingsite. Garnet porphyroblasts are zoned with increasing almandine and spessartine contents and decreasing grossular and pyrope contents from core (Alm46Prp32 Grs21Sps2) to rim (Alm52Prp26 Grs19Sps3). This pattern is interpreted as a retrograde diffusion zoning with the preserved core chemistry representing the peak metamorphic composition. Mineral reaction textures occur in the form of monomineralic and composite plagioclase ± orthopyroxene ± amphibole ± biotite ± magnetite coronas around garnet porphyroblasts. Thermobarometry indicates peak metamorphic conditions of up to 1.57 ± 0.14 GPa and 949 ± 92 °C (stage I), corresponding to crustal depths of ∼55 km. Zircon yielded an U-Pb age of 557 ± 16 Ma, inferred to date crystallization of zircon during peak or immediately post-peak metamorphism. Formation of plagioclase + orthopyroxene-bearing coronas surrounding garnet indicates a near-isothermal decompression of the high-pressure granulites to lower pressure granulite facies conditions (stage II). Development of plagioclase + amphibole-coronas enclosing the same garnet porphyroblasts shows subsequent cooling into amphibolite facies conditions (stage III). Symplectitic textures of the corona assemblages indicate rapid decompression. The high-pressure granulite facies metamorphism of the Lurio Belt, followed by near-isothermal decompression and subsequent cooling, is in accordance with a long-lived tectonic history accompanied by high magmatic activity in the Lurio Belt during the late Neoproterozoic-early Palaeozoic East-African-Antarctic orogeny. © 2007 Blackwell Publishing Ltd. Article in Journal/Newspaper Antarc* Antarctic IRIS Università degli Studi di Bologna (CRIS - Current Research Information System) Journal of Metamorphic Geology 25 9 935 952 |
institution |
Open Polar |
collection |
IRIS Università degli Studi di Bologna (CRIS - Current Research Information System) |
op_collection_id |
ftunibolognairis |
language |
English |
topic |
Corona texture High-pressure granulite Isothermal decompression Lurio Belt Pan-African Geology |
spellingShingle |
Corona texture High-pressure granulite Isothermal decompression Lurio Belt Pan-African Geology Engvik, Ane K Tveten, E. Bingen, B. Erambert, M. Feito, P. De Azavedo, S. VIOLA, GIULIO P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique |
topic_facet |
Corona texture High-pressure granulite Isothermal decompression Lurio Belt Pan-African Geology |
description |
Pan-African high-pressure granulites occur as boudins and layers in the Lurio Belt in north-eastern Mozambique, eastern Africa. Mafic granulites contain the mineral assemblage garnet + clinopyroxene + plagioclase + quartz ± magnesiohastingsite. Garnet porphyroblasts are zoned with increasing almandine and spessartine contents and decreasing grossular and pyrope contents from core (Alm46Prp32 Grs21Sps2) to rim (Alm52Prp26 Grs19Sps3). This pattern is interpreted as a retrograde diffusion zoning with the preserved core chemistry representing the peak metamorphic composition. Mineral reaction textures occur in the form of monomineralic and composite plagioclase ± orthopyroxene ± amphibole ± biotite ± magnetite coronas around garnet porphyroblasts. Thermobarometry indicates peak metamorphic conditions of up to 1.57 ± 0.14 GPa and 949 ± 92 °C (stage I), corresponding to crustal depths of ∼55 km. Zircon yielded an U-Pb age of 557 ± 16 Ma, inferred to date crystallization of zircon during peak or immediately post-peak metamorphism. Formation of plagioclase + orthopyroxene-bearing coronas surrounding garnet indicates a near-isothermal decompression of the high-pressure granulites to lower pressure granulite facies conditions (stage II). Development of plagioclase + amphibole-coronas enclosing the same garnet porphyroblasts shows subsequent cooling into amphibolite facies conditions (stage III). Symplectitic textures of the corona assemblages indicate rapid decompression. The high-pressure granulite facies metamorphism of the Lurio Belt, followed by near-isothermal decompression and subsequent cooling, is in accordance with a long-lived tectonic history accompanied by high magmatic activity in the Lurio Belt during the late Neoproterozoic-early Palaeozoic East-African-Antarctic orogeny. © 2007 Blackwell Publishing Ltd. |
author2 |
Engvik, Ane K Tveten, E. Bingen, B. Viola, Giulio Erambert, M. Feito, P. De Azavedo, S. |
format |
Article in Journal/Newspaper |
author |
Engvik, Ane K Tveten, E. Bingen, B. Erambert, M. Feito, P. De Azavedo, S. VIOLA, GIULIO |
author_facet |
Engvik, Ane K Tveten, E. Bingen, B. Erambert, M. Feito, P. De Azavedo, S. VIOLA, GIULIO |
author_sort |
Engvik, Ane K |
title |
P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique |
title_short |
P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique |
title_full |
P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique |
title_fullStr |
P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique |
title_full_unstemmed |
P-T-t evolution and textural evidence for decompression of Pan-African high-pressure granulites, Lurio Belt, north-eastern Mozambique |
title_sort |
p-t-t evolution and textural evidence for decompression of pan-african high-pressure granulites, lurio belt, north-eastern mozambique |
publishDate |
2007 |
url |
http://hdl.handle.net/11585/567061 https://doi.org/10.1111/j.1525-1314.2007.00736.x |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000250943000001 volume:25 issue:9 firstpage:935 lastpage:952 numberofpages:18 journal:JOURNAL OF METAMORPHIC GEOLOGY http://hdl.handle.net/11585/567061 doi:10.1111/j.1525-1314.2007.00736.x info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-36248963663 |
op_doi |
https://doi.org/10.1111/j.1525-1314.2007.00736.x |
container_title |
Journal of Metamorphic Geology |
container_volume |
25 |
container_issue |
9 |
container_start_page |
935 |
op_container_end_page |
952 |
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1810492926184128512 |