Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica
Abstract The Pleiades Volcanic Field is made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. Erupted products vary from hawaiite to trachyte,...
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2024-07-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1029/2024GC011509 |
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| author | Samuele Agostini Noemi Leone John L. Smellie Sergio Rocchi |
| author_facet | Samuele Agostini Noemi Leone John L. Smellie Sergio Rocchi |
| author_sort | Samuele Agostini |
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| description | Abstract The Pleiades Volcanic Field is made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. Erupted products vary from hawaiite to trachyte, defining a complete mild Na‐alkaline differentiation trend. Mafic samples are characterized by multi‐elemental patterns typical of OIB magmas, moderately low 87Sr/86Sr (0.7037) and high 143Nd/144Nd (0.51284), with a clear within‐plate affinity, indicating a subcontinental lithospheric source. With increasing SiO2, 87Sr/86Sr ratios increase up to 0.7052 and 143Nd/144Nd decrease to 0.51277, supporting the hypothesis of open‐system evolution, with significant crustal assimilation during fractional crystallization. The erupted volume of most evolved products (∼7 km3), according to fractionation models, suggests that primitive magmas should have been more than 10 times larger, indicating the occurrence of a large magma plumbing system, unexpected for a volcanic field of monogenetic scoria cones. The occurrence of a complete fractionation trend with large magma chambers and large assimilation rate is unusual, if not unique, among the alkali basaltic volcanic fields and it is matched by a climax of activity during the last glacial maximum (30 ka), as indicated by new 40Ar‐39Ar ages (30 ± 3 ka and 25 ± 2 ka) for samples from the two most prominent edifices. Therefore, we hypothesize a role of a thick ice cap in suppressing eruptions and ultimately leading to prolonged magma residence time in the subsurface, favoring significant fractionation coupled with unusual high rates of crustal assimilation. |
| format | Article |
| id | doaj-art-efaeed2abe6f43988ba400c084a5578e |
| institution | Kabale University |
| issn | 1525-2027 |
| language | English |
| publishDate | 2024-07-01 |
| publisher | Wiley |
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| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj-art-efaeed2abe6f43988ba400c084a5578e2025-08-20T03:49:32ZengWileyGeochemistry, Geophysics, Geosystems1525-20272024-07-01257n/an/a10.1029/2024GC011509Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, AntarcticaSamuele Agostini0Noemi Leone1John L. Smellie2Sergio Rocchi3Istituto di Geoscienze e Georisorse Consiglio Nazionale delle Ricerche Pisa ItalyDipartimento di Scienze della Terra Università di Pisa Pisa ItalyDepartment of Geology University of Leicester Leicester UKDipartimento di Scienze della Terra Università di Pisa Pisa ItalyAbstract The Pleiades Volcanic Field is made up of some 20 monogenetic, partly overlapping scoria and spatter cones, erupted in the last 900 ka, cropping out from the ice close to the head of the Mariner Glacier in northern Victoria Land, Antarctica. Erupted products vary from hawaiite to trachyte, defining a complete mild Na‐alkaline differentiation trend. Mafic samples are characterized by multi‐elemental patterns typical of OIB magmas, moderately low 87Sr/86Sr (0.7037) and high 143Nd/144Nd (0.51284), with a clear within‐plate affinity, indicating a subcontinental lithospheric source. With increasing SiO2, 87Sr/86Sr ratios increase up to 0.7052 and 143Nd/144Nd decrease to 0.51277, supporting the hypothesis of open‐system evolution, with significant crustal assimilation during fractional crystallization. The erupted volume of most evolved products (∼7 km3), according to fractionation models, suggests that primitive magmas should have been more than 10 times larger, indicating the occurrence of a large magma plumbing system, unexpected for a volcanic field of monogenetic scoria cones. The occurrence of a complete fractionation trend with large magma chambers and large assimilation rate is unusual, if not unique, among the alkali basaltic volcanic fields and it is matched by a climax of activity during the last glacial maximum (30 ka), as indicated by new 40Ar‐39Ar ages (30 ± 3 ka and 25 ± 2 ka) for samples from the two most prominent edifices. Therefore, we hypothesize a role of a thick ice cap in suppressing eruptions and ultimately leading to prolonged magma residence time in the subsurface, favoring significant fractionation coupled with unusual high rates of crustal assimilation.https://doi.org/10.1029/2024GC011509Pleiades volcanic fieldAntarcticapetrologygeochemistryvolcanologyclimate change |
| spellingShingle | Samuele Agostini Noemi Leone John L. Smellie Sergio Rocchi Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica Geochemistry, Geophysics, Geosystems Pleiades volcanic field Antarctica petrology geochemistry volcanology climate change |
| title | Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica |
| title_full | Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica |
| title_fullStr | Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica |
| title_full_unstemmed | Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica |
| title_short | Magma Differentiation, Contamination/Mixing and Eruption Modulated by Glacial Load—The Volcanic Complex of The Pleiades, Antarctica |
| title_sort | magma differentiation contamination mixing and eruption modulated by glacial load the volcanic complex of the pleiades antarctica |
| topic | Pleiades volcanic field Antarctica petrology geochemistry volcanology climate change |
| url | https://doi.org/10.1029/2024GC011509 |
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