Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina
Neogene plateau lavas in Patagonia, southern Argentina, east of the volcanic gap between the Southern and Austral Volcanic Zones at 46·5° and 49·5°S are linked with asthenospheric slab window processes associated with the collision of a Chile Ridge segment with the Chile Trench at 12 Ma. The strong...
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Montclair State University Digital Commons
2001
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ftmontclairstuni:oai:digitalcommons.montclair.edu:earth-environ-studies-facpubs-1398 2023-07-23T04:15:20+02:00 Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina Gorring, Matthew Kay, Suzanne M. 2001-01-01T08:00:00Z https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/399 https://doi.org/10.1093/petrology/42.6.1067 unknown Montclair State University Digital Commons https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/399 doi:10.1093/petrology/42.6.1067 Department of Earth and Environmental Studies Faculty Scholarship and Creative Works Back-arc processes Mantle chemistry Plateau basalt petrogenesis Slab window magmatism Southern patagonia text 2001 ftmontclairstuni https://doi.org/10.1093/petrology/42.6.1067 2023-07-03T21:48:28Z Neogene plateau lavas in Patagonia, southern Argentina, east of the volcanic gap between the Southern and Austral Volcanic Zones at 46·5° and 49·5°S are linked with asthenospheric slab window processes associated with the collision of a Chile Ridge segment with the Chile Trench at 12 Ma. The strong ocean-island basalt (OIB)-like geochemical signatures (La/Ta <20;; Ba/La <20; 87Sr/86Sr = 0·7035-0·7046; 143Nd/144Nd = 0·51290-0·51261; 206Pb/204Pb = 18·3-18·8; 207Pb204Pb = 15·57-15·65; 208Pb/204Pb = 38·4-38·7) of these Patagonian slab window lavas contrast with the mid-ocean ridge basalt (MORB)-like, depleted mantle signatures of slab window lavas elsewhere in the cordillera, (e.g. Antarctic Peninsula; Baja California). The Patagonian lavas can be divided into a voluminous ∼ 12-5 Ma, tholeeitic main-plateau sequence (48-55% SiO2; 4-5% Na2O 〈 K2O) and a less voluminous ∼ 7-2 Ma alkaline post-plateau sequence (43-49% SiO2; 5-8% Na2O 〈 K2O). Moderately high FeOT(9-11%), and low heavy rare earth element (HREE), γ, and Sc concentrations in all lavas are consistent with melt generation just below the garnet-spinel transition at a depth of ∼ 70 km. The main-plateau lavas from the western back-arc can be modeled by ∼ 10-15% partial melting of an OIB-like asthenospheric mantle source with additions form slab fluid-melt components coupled with crustal contamination (AFC). A three-stage petrogenetic model is envisaged: (1) decompression melting and source region contamination of an OIB-like subslab asthenospheric source by slab melts of the trailing edge of the subducted Nazca Plate; (2) minor contamination of slab window melts with arc components 'stored' in the supraslab mantle wedge and/or basal continental lithosphere; (3) further modification by addition of crustal components during magma ascent. The main-plateau lavas from the eastern back-arc can be modeled by ∼ 7% partial melting of the same asthenospheric source as the influence of arc components diminishes and the intensity of mantle upwelling into the slab ... Text Antarc* Antarctic Antarctic Peninsula Ocean Island Montclair State University Digital Commons Antarctic Antarctic Peninsula Baja Austral Patagonia Argentina Chile Trench ENVELOPE(-75.760,-75.760,-53.123,-53.123) Journal of Petrology 42 6 1067 1094 |
institution |
Open Polar |
collection |
Montclair State University Digital Commons |
op_collection_id |
ftmontclairstuni |
language |
unknown |
topic |
Back-arc processes Mantle chemistry Plateau basalt petrogenesis Slab window magmatism Southern patagonia |
spellingShingle |
Back-arc processes Mantle chemistry Plateau basalt petrogenesis Slab window magmatism Southern patagonia Gorring, Matthew Kay, Suzanne M. Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina |
topic_facet |
Back-arc processes Mantle chemistry Plateau basalt petrogenesis Slab window magmatism Southern patagonia |
description |
Neogene plateau lavas in Patagonia, southern Argentina, east of the volcanic gap between the Southern and Austral Volcanic Zones at 46·5° and 49·5°S are linked with asthenospheric slab window processes associated with the collision of a Chile Ridge segment with the Chile Trench at 12 Ma. The strong ocean-island basalt (OIB)-like geochemical signatures (La/Ta <20;; Ba/La <20; 87Sr/86Sr = 0·7035-0·7046; 143Nd/144Nd = 0·51290-0·51261; 206Pb/204Pb = 18·3-18·8; 207Pb204Pb = 15·57-15·65; 208Pb/204Pb = 38·4-38·7) of these Patagonian slab window lavas contrast with the mid-ocean ridge basalt (MORB)-like, depleted mantle signatures of slab window lavas elsewhere in the cordillera, (e.g. Antarctic Peninsula; Baja California). The Patagonian lavas can be divided into a voluminous ∼ 12-5 Ma, tholeeitic main-plateau sequence (48-55% SiO2; 4-5% Na2O 〈 K2O) and a less voluminous ∼ 7-2 Ma alkaline post-plateau sequence (43-49% SiO2; 5-8% Na2O 〈 K2O). Moderately high FeOT(9-11%), and low heavy rare earth element (HREE), γ, and Sc concentrations in all lavas are consistent with melt generation just below the garnet-spinel transition at a depth of ∼ 70 km. The main-plateau lavas from the western back-arc can be modeled by ∼ 10-15% partial melting of an OIB-like asthenospheric mantle source with additions form slab fluid-melt components coupled with crustal contamination (AFC). A three-stage petrogenetic model is envisaged: (1) decompression melting and source region contamination of an OIB-like subslab asthenospheric source by slab melts of the trailing edge of the subducted Nazca Plate; (2) minor contamination of slab window melts with arc components 'stored' in the supraslab mantle wedge and/or basal continental lithosphere; (3) further modification by addition of crustal components during magma ascent. The main-plateau lavas from the eastern back-arc can be modeled by ∼ 7% partial melting of the same asthenospheric source as the influence of arc components diminishes and the intensity of mantle upwelling into the slab ... |
format |
Text |
author |
Gorring, Matthew Kay, Suzanne M. |
author_facet |
Gorring, Matthew Kay, Suzanne M. |
author_sort |
Gorring, Matthew |
title |
Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina |
title_short |
Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina |
title_full |
Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina |
title_fullStr |
Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina |
title_full_unstemmed |
Mantle Processes and Sources of Neogene Slab Window Magmas from Southern Patagonia, Argentina |
title_sort |
mantle processes and sources of neogene slab window magmas from southern patagonia, argentina |
publisher |
Montclair State University Digital Commons |
publishDate |
2001 |
url |
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/399 https://doi.org/10.1093/petrology/42.6.1067 |
long_lat |
ENVELOPE(-75.760,-75.760,-53.123,-53.123) |
geographic |
Antarctic Antarctic Peninsula Baja Austral Patagonia Argentina Chile Trench |
geographic_facet |
Antarctic Antarctic Peninsula Baja Austral Patagonia Argentina Chile Trench |
genre |
Antarc* Antarctic Antarctic Peninsula Ocean Island |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Ocean Island |
op_source |
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works |
op_relation |
https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/399 doi:10.1093/petrology/42.6.1067 |
op_doi |
https://doi.org/10.1093/petrology/42.6.1067 |
container_title |
Journal of Petrology |
container_volume |
42 |
container_issue |
6 |
container_start_page |
1067 |
op_container_end_page |
1094 |
_version_ |
1772189346801123328 |