Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record
Martin Vaz Archipelago is located at the parallel 20°S, 1200 km away from the Brazilian coastline and is composed of Plio-Pleistocenic alkaline rocks that represent the last volcanic event of the Vitória-Trindade Ridge. The Archipelago is divided into three main units: Pico das Gaivotas Unit (i) is...
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ftria:oai:ria.ua.pt:10773/37242 2023-06-11T04:16:42+02:00 Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record Leite de Oliveira, André Costa dos Santos, Anderson Nogueira, Camila Cardoso Maia, Thaís Mothé Geraldes, Mauro César 2021-01 http://hdl.handle.net/10773/37242 https://doi.org/10.1016/j.jsames.2020.102951 eng eng Elsevier 557146/2009–7 26/2009 88881.177228/2018–01 APQ1 2019 n 210.179/2019 0895-9811 http://hdl.handle.net/10773/37242 doi:10.1016/j.jsames.2020.102951 1873-0647 102951 openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ Martin vaz archipelago Magma chamber replenishment Magma mixing Metasomatism Green core clinopyroxenes Pyroxene thermobarometry article 2021 ftria https://doi.org/10.1016/j.jsames.2020.102951 2023-04-26T00:07:50Z Martin Vaz Archipelago is located at the parallel 20°S, 1200 km away from the Brazilian coastline and is composed of Plio-Pleistocenic alkaline rocks that represent the last volcanic event of the Vitória-Trindade Ridge. The Archipelago is divided into three main units: Pico das Gaivotas Unit (i) is made up of nosean-phonolite and phono-tephrite domes and tephri-phonolite dykes with clinopyroxene, nosean and potassic feldspar phenocrysts, and scarce kaersutite anhedral phenocrysts; the Bandeira Unit (ii), in turn, comprises melanephelinitic and basanitic lava flows with olivine and clinopyroxene (diopside) phenocrysts; and lastly, the Basal Unit (iii) is composed of pyroclastic deposits with tuffs, lapilli-tuffs and lapillite. The clinopyroxene phenocrysts from Pico das Gaivotas and Bandeira Units have anhedral green cores with sieved and poikilitic textures and show reaction rims composed of opaque minerals, indicating disequilibrium and compositional changes in the liquid. This study provides mineral chemistry data indicating that clinopyroxene rims are more primitive (Mg# 57.46–84.12) and enriched in Al–Ti–Fe3+-Ca compared to the Fe-rich green-cores, probably related with a more primitive Ca-rich magma input in the magmatic chamber after the green-core crystallization from a different liquid. Olivine crystals from Bandeira Unit show resorption features and no compositional affinity with the analyzed liquid, indicating that these crystals have a xenocrystic origin from mantle peridotitic source. Clinopyroxene geothermobarometry data suggest different pressure and temperature conditions for cores and rims during crystallization, reflecting a polybaric evolutionary history. Pico das Gaivotas Unit clinopyroxene phenocrysts suggest a particularly higher-pressure environment, and a complex evolutionary history. published Article in Journal/Newspaper South Atlantic Ocean Repositório Institucional da Universidade de Aveiro (RIA) Journal of South American Earth Sciences 105 102951 |
institution |
Open Polar |
collection |
Repositório Institucional da Universidade de Aveiro (RIA) |
op_collection_id |
ftria |
language |
English |
topic |
Martin vaz archipelago Magma chamber replenishment Magma mixing Metasomatism Green core clinopyroxenes Pyroxene thermobarometry |
spellingShingle |
Martin vaz archipelago Magma chamber replenishment Magma mixing Metasomatism Green core clinopyroxenes Pyroxene thermobarometry Leite de Oliveira, André Costa dos Santos, Anderson Nogueira, Camila Cardoso Maia, Thaís Mothé Geraldes, Mauro César Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record |
topic_facet |
Martin vaz archipelago Magma chamber replenishment Magma mixing Metasomatism Green core clinopyroxenes Pyroxene thermobarometry |
description |
Martin Vaz Archipelago is located at the parallel 20°S, 1200 km away from the Brazilian coastline and is composed of Plio-Pleistocenic alkaline rocks that represent the last volcanic event of the Vitória-Trindade Ridge. The Archipelago is divided into three main units: Pico das Gaivotas Unit (i) is made up of nosean-phonolite and phono-tephrite domes and tephri-phonolite dykes with clinopyroxene, nosean and potassic feldspar phenocrysts, and scarce kaersutite anhedral phenocrysts; the Bandeira Unit (ii), in turn, comprises melanephelinitic and basanitic lava flows with olivine and clinopyroxene (diopside) phenocrysts; and lastly, the Basal Unit (iii) is composed of pyroclastic deposits with tuffs, lapilli-tuffs and lapillite. The clinopyroxene phenocrysts from Pico das Gaivotas and Bandeira Units have anhedral green cores with sieved and poikilitic textures and show reaction rims composed of opaque minerals, indicating disequilibrium and compositional changes in the liquid. This study provides mineral chemistry data indicating that clinopyroxene rims are more primitive (Mg# 57.46–84.12) and enriched in Al–Ti–Fe3+-Ca compared to the Fe-rich green-cores, probably related with a more primitive Ca-rich magma input in the magmatic chamber after the green-core crystallization from a different liquid. Olivine crystals from Bandeira Unit show resorption features and no compositional affinity with the analyzed liquid, indicating that these crystals have a xenocrystic origin from mantle peridotitic source. Clinopyroxene geothermobarometry data suggest different pressure and temperature conditions for cores and rims during crystallization, reflecting a polybaric evolutionary history. Pico das Gaivotas Unit clinopyroxene phenocrysts suggest a particularly higher-pressure environment, and a complex evolutionary history. published |
format |
Article in Journal/Newspaper |
author |
Leite de Oliveira, André Costa dos Santos, Anderson Nogueira, Camila Cardoso Maia, Thaís Mothé Geraldes, Mauro César |
author_facet |
Leite de Oliveira, André Costa dos Santos, Anderson Nogueira, Camila Cardoso Maia, Thaís Mothé Geraldes, Mauro César |
author_sort |
Leite de Oliveira, André |
title |
Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record |
title_short |
Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record |
title_full |
Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record |
title_fullStr |
Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record |
title_full_unstemmed |
Green core clinopyroxenes from Martin Vaz Archipelago Plio-Pleistocenic alkaline rocks, South Atlantic Ocean, Brazil: a magma mixing and polybaric crystallization record |
title_sort |
green core clinopyroxenes from martin vaz archipelago plio-pleistocenic alkaline rocks, south atlantic ocean, brazil: a magma mixing and polybaric crystallization record |
publisher |
Elsevier |
publishDate |
2021 |
url |
http://hdl.handle.net/10773/37242 https://doi.org/10.1016/j.jsames.2020.102951 |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_relation |
557146/2009–7 26/2009 88881.177228/2018–01 APQ1 2019 n 210.179/2019 0895-9811 http://hdl.handle.net/10773/37242 doi:10.1016/j.jsames.2020.102951 1873-0647 102951 |
op_rights |
openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ |
op_doi |
https://doi.org/10.1016/j.jsames.2020.102951 |
container_title |
Journal of South American Earth Sciences |
container_volume |
105 |
container_start_page |
102951 |
_version_ |
1768375214116175872 |