Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina)
A detailed petrological study of mafic and ultramafic xenoliths from Cerro del Fraile (Southern Patagonia, Argentina) was developed to highlight (1) the mineralogical and geochemical composition of the lithospheric mantle beneath the area, (2) the nature of the metasomatizing agents that infiltrate...
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Online Access: | http://hdl.handle.net/11392/1779899 https://doi.org/10.1093/petrology/egt010 |
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ftunivferrarair:oai:iris.unife.it:11392/1779899 2024-02-11T09:55:44+01:00 Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) FACCINI, Barbara BONADIMAN, Costanza COLTORTI, Massimo SIENA, Franca Grègoire M. Faccini, Barbara Bonadiman, Costanza Coltorti, Massimo Grègoire, M. Siena, Franca 2013 STAMPA http://hdl.handle.net/11392/1779899 https://doi.org/10.1093/petrology/egt010 eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000319478600006 volume:54 issue:6 firstpage:1211 lastpage:1258 numberofpages:48 journal:JOURNAL OF PETROLOGY http://hdl.handle.net/11392/1779899 doi:10.1093/petrology/egt010 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-84884750326 subduction mantle xenoliths slab-melt metasomatism info:eu-repo/semantics/article 2013 ftunivferrarair https://doi.org/10.1093/petrology/egt010 2024-01-24T17:35:44Z A detailed petrological study of mafic and ultramafic xenoliths from Cerro del Fraile (Southern Patagonia, Argentina) was developed to highlight (1) the mineralogical and geochemical composition of the lithospheric mantle beneath the area, (2) the nature of the metasomatizing agents that infiltrate the mantle wedge above the Antarctic plate, (3) the processes that allow the mantle to be refertilized, and (4) the nature of the material dragged down in the subduction zone and recycled within the South Patagonian sub-arc mantle. Major and trace element analyses of clinopyroxene and orthopyroxene in peridotitic and pyroxenitic rocks suggest that a proto-adakite, deriving from the melting of the subducting Antarctic plate, was responsible for the metasomatic features of the peridotitic rocks and the crystallization of the pyroxenites. A few composite xenoliths bridge the two processesçperidotite enrichment and pyroxenite crystallizationçindicating that the variously depleted mantle reacts with the incoming melt to generate a newly fertile mantle domain.This reaction occurs under reducing conditions [log fO2 (QFM) ^1·21 to ^0·34], unusual for mantle wedge settings. Heavy rare earth elements and Al2O3 and MgO contents in pyroxenes indicate a partial melting degree varying from 10 to 25%.The peculiar enrichment in Zr (^Hf),Th and U of the pyroxenes indicates the melting of oceanic sediments, which include manganese nodules and, possibly, organic matter, in agreement with the estimated low oxygen fugacity conditions. Some geochemical analogies have been found between the calculated metasomatic melts and the Austral Volcanic Zone adakites. In this case, the amount of sediment involved in the genesis of the infiltrating melts is larger than that previously proposed for the genesis of the erupted Patagonian adakites. Chemical^physical conditions favouring the upward percolation through the mantle wedge of these SiO2-rich and viscous melts are also discussed. Article in Journal/Newspaper Antarc* Antarctic Università degli Studi di Ferrara: CINECA IRIS Antarctic Argentina Austral Patagonia The Antarctic Journal of Petrology 54 6 1211 1258 |
institution |
Open Polar |
collection |
Università degli Studi di Ferrara: CINECA IRIS |
op_collection_id |
ftunivferrarair |
language |
English |
topic |
subduction mantle xenoliths slab-melt metasomatism |
spellingShingle |
subduction mantle xenoliths slab-melt metasomatism FACCINI, Barbara BONADIMAN, Costanza COLTORTI, Massimo SIENA, Franca Grègoire M. Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) |
topic_facet |
subduction mantle xenoliths slab-melt metasomatism |
description |
A detailed petrological study of mafic and ultramafic xenoliths from Cerro del Fraile (Southern Patagonia, Argentina) was developed to highlight (1) the mineralogical and geochemical composition of the lithospheric mantle beneath the area, (2) the nature of the metasomatizing agents that infiltrate the mantle wedge above the Antarctic plate, (3) the processes that allow the mantle to be refertilized, and (4) the nature of the material dragged down in the subduction zone and recycled within the South Patagonian sub-arc mantle. Major and trace element analyses of clinopyroxene and orthopyroxene in peridotitic and pyroxenitic rocks suggest that a proto-adakite, deriving from the melting of the subducting Antarctic plate, was responsible for the metasomatic features of the peridotitic rocks and the crystallization of the pyroxenites. A few composite xenoliths bridge the two processesçperidotite enrichment and pyroxenite crystallizationçindicating that the variously depleted mantle reacts with the incoming melt to generate a newly fertile mantle domain.This reaction occurs under reducing conditions [log fO2 (QFM) ^1·21 to ^0·34], unusual for mantle wedge settings. Heavy rare earth elements and Al2O3 and MgO contents in pyroxenes indicate a partial melting degree varying from 10 to 25%.The peculiar enrichment in Zr (^Hf),Th and U of the pyroxenes indicates the melting of oceanic sediments, which include manganese nodules and, possibly, organic matter, in agreement with the estimated low oxygen fugacity conditions. Some geochemical analogies have been found between the calculated metasomatic melts and the Austral Volcanic Zone adakites. In this case, the amount of sediment involved in the genesis of the infiltrating melts is larger than that previously proposed for the genesis of the erupted Patagonian adakites. Chemical^physical conditions favouring the upward percolation through the mantle wedge of these SiO2-rich and viscous melts are also discussed. |
author2 |
Faccini, Barbara Bonadiman, Costanza Coltorti, Massimo Grègoire, M. Siena, Franca |
format |
Article in Journal/Newspaper |
author |
FACCINI, Barbara BONADIMAN, Costanza COLTORTI, Massimo SIENA, Franca Grègoire M. |
author_facet |
FACCINI, Barbara BONADIMAN, Costanza COLTORTI, Massimo SIENA, Franca Grègoire M. |
author_sort |
FACCINI, Barbara |
title |
Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) |
title_short |
Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) |
title_full |
Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) |
title_fullStr |
Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) |
title_full_unstemmed |
Oceanic Material Recycled within the Sub-Patagonian Lithospheric Mantle (Cerro del Fraile, Argentina) |
title_sort |
oceanic material recycled within the sub-patagonian lithospheric mantle (cerro del fraile, argentina) |
publishDate |
2013 |
url |
http://hdl.handle.net/11392/1779899 https://doi.org/10.1093/petrology/egt010 |
geographic |
Antarctic Argentina Austral Patagonia The Antarctic |
geographic_facet |
Antarctic Argentina Austral Patagonia The Antarctic |
genre |
Antarc* Antarctic |
genre_facet |
Antarc* Antarctic |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000319478600006 volume:54 issue:6 firstpage:1211 lastpage:1258 numberofpages:48 journal:JOURNAL OF PETROLOGY http://hdl.handle.net/11392/1779899 doi:10.1093/petrology/egt010 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-84884750326 |
op_doi |
https://doi.org/10.1093/petrology/egt010 |
container_title |
Journal of Petrology |
container_volume |
54 |
container_issue |
6 |
container_start_page |
1211 |
op_container_end_page |
1258 |
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1790598562179973120 |