The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc
The collision of a divergent ocean ridge may evolve into two end cases: in the continuity of ocean-floor subduction, or in the detachment of the subducted plate. The northern Patagonia active plate margin has the unique situation that in Cenozoic time it has been subjected to two divergent ridge col...
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ftdoajarticles:oai:doaj.org/article:cd38278b01f84095b413ee9474c28afa 2023-10-09T21:47:03+02:00 The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc Eugenio Aragón Lucio Pinotti Fernando D′Eramo Antonio Castro Osvaldo Rabbia Jorge Coniglio Manuel Demartis Irene Hernando Claudia E. Cavarozzi Yolanda E. Aguilera 2013-07-01T00:00:00Z https://doi.org/10.1016/j.gsf.2012.12.004 https://doaj.org/article/cd38278b01f84095b413ee9474c28afa EN eng Elsevier http://www.sciencedirect.com/science/article/pii/S1674987112001533 https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2012.12.004 https://doaj.org/article/cd38278b01f84095b413ee9474c28afa Geoscience Frontiers, Vol 4, Iss 4, Pp 377-388 (2013) Andes Active ridge collision Subduction-transform transition Slab window volcanism Synextensional calc-alkaline Bimodal volcanism Geology QE1-996.5 article 2013 ftdoajarticles https://doi.org/10.1016/j.gsf.2012.12.004 2023-09-10T00:49:42Z The collision of a divergent ocean ridge may evolve into two end cases: in the continuity of ocean-floor subduction, or in the detachment of the subducted plate. The northern Patagonia active plate margin has the unique situation that in Cenozoic time it has been subjected to two divergent ridge collisions, each one representing one of the end members. The Neogene Antarctica-Nazca divergent ridge collision evolved as a continuous ocean-floor subduction system, promoting a magmatic hiatus at the arc axis, the obduction of part of the ridge ocean-floor in the fore-arc, and basaltic volcanism in the back-arc. In contrast, the Paleogene Farallon-Aluk divergent ridge collision evolved into a transform margin, with the detachment and sinking of the Aluk plate and the development of a large slab window. As in the previous case, this collision promoted a magmatic hiatus at the arc axis, but the tectono-magmatic scenario changed to postorogenic synextensional volcanism that spread to the former fore-arc (basalt, andesite, rhyolite) and former back-arc (bimodal ignimbrite flare-up, basalt). Geochemistry of this slab window synextensional volcanism shows more MORB-like basalts towards the former fore-arc, and MORB-OIB-like basalts towards the former back-arc. Instead, an isolated undeformable crustal block in the former back-arc, with an “epeirogenic” response to the slab window and extensional regime, was covered by OIB-type basalts after uplift. Major elements show that slab window basalts reach TiO2 values up to 3 wt%, as compared with the top value of 1.5 wt% of arc magmas. Besides, the MgO with respect to (FeOt + Al2O3) ratio helps to distinguish slab window magma changes from the former fore-arc to the former back-arc and also with respect to the “epeirogenic” block. Higher contents of HFS elements such as Nb and Ta also help to distinguish this slab window from arc magmas and also, to distinguish slab window magma changes from the former fore-arc to the former back-arc and “epeirogenic” block settings. The isotope ... Article in Journal/Newspaper Antarc* Antarctica Directory of Open Access Journals: DOAJ Articles Patagonia Geoscience Frontiers 4 4 377 388 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Andes Active ridge collision Subduction-transform transition Slab window volcanism Synextensional calc-alkaline Bimodal volcanism Geology QE1-996.5 |
spellingShingle |
Andes Active ridge collision Subduction-transform transition Slab window volcanism Synextensional calc-alkaline Bimodal volcanism Geology QE1-996.5 Eugenio Aragón Lucio Pinotti Fernando D′Eramo Antonio Castro Osvaldo Rabbia Jorge Coniglio Manuel Demartis Irene Hernando Claudia E. Cavarozzi Yolanda E. Aguilera The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc |
topic_facet |
Andes Active ridge collision Subduction-transform transition Slab window volcanism Synextensional calc-alkaline Bimodal volcanism Geology QE1-996.5 |
description |
The collision of a divergent ocean ridge may evolve into two end cases: in the continuity of ocean-floor subduction, or in the detachment of the subducted plate. The northern Patagonia active plate margin has the unique situation that in Cenozoic time it has been subjected to two divergent ridge collisions, each one representing one of the end members. The Neogene Antarctica-Nazca divergent ridge collision evolved as a continuous ocean-floor subduction system, promoting a magmatic hiatus at the arc axis, the obduction of part of the ridge ocean-floor in the fore-arc, and basaltic volcanism in the back-arc. In contrast, the Paleogene Farallon-Aluk divergent ridge collision evolved into a transform margin, with the detachment and sinking of the Aluk plate and the development of a large slab window. As in the previous case, this collision promoted a magmatic hiatus at the arc axis, but the tectono-magmatic scenario changed to postorogenic synextensional volcanism that spread to the former fore-arc (basalt, andesite, rhyolite) and former back-arc (bimodal ignimbrite flare-up, basalt). Geochemistry of this slab window synextensional volcanism shows more MORB-like basalts towards the former fore-arc, and MORB-OIB-like basalts towards the former back-arc. Instead, an isolated undeformable crustal block in the former back-arc, with an “epeirogenic” response to the slab window and extensional regime, was covered by OIB-type basalts after uplift. Major elements show that slab window basalts reach TiO2 values up to 3 wt%, as compared with the top value of 1.5 wt% of arc magmas. Besides, the MgO with respect to (FeOt + Al2O3) ratio helps to distinguish slab window magma changes from the former fore-arc to the former back-arc and also with respect to the “epeirogenic” block. Higher contents of HFS elements such as Nb and Ta also help to distinguish this slab window from arc magmas and also, to distinguish slab window magma changes from the former fore-arc to the former back-arc and “epeirogenic” block settings. The isotope ... |
format |
Article in Journal/Newspaper |
author |
Eugenio Aragón Lucio Pinotti Fernando D′Eramo Antonio Castro Osvaldo Rabbia Jorge Coniglio Manuel Demartis Irene Hernando Claudia E. Cavarozzi Yolanda E. Aguilera |
author_facet |
Eugenio Aragón Lucio Pinotti Fernando D′Eramo Antonio Castro Osvaldo Rabbia Jorge Coniglio Manuel Demartis Irene Hernando Claudia E. Cavarozzi Yolanda E. Aguilera |
author_sort |
Eugenio Aragón |
title |
The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc |
title_short |
The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc |
title_full |
The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc |
title_fullStr |
The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc |
title_full_unstemmed |
The Farallon-Aluk ridge collision with South America: Implications for the geochemical changes of slab window magmas from fore- to back-arc |
title_sort |
farallon-aluk ridge collision with south america: implications for the geochemical changes of slab window magmas from fore- to back-arc |
publisher |
Elsevier |
publishDate |
2013 |
url |
https://doi.org/10.1016/j.gsf.2012.12.004 https://doaj.org/article/cd38278b01f84095b413ee9474c28afa |
geographic |
Patagonia |
geographic_facet |
Patagonia |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Geoscience Frontiers, Vol 4, Iss 4, Pp 377-388 (2013) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S1674987112001533 https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2012.12.004 https://doaj.org/article/cd38278b01f84095b413ee9474c28afa |
op_doi |
https://doi.org/10.1016/j.gsf.2012.12.004 |
container_title |
Geoscience Frontiers |
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4 |
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4 |
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377 |
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388 |
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1779309747508346880 |