Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province
Abstract Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 m (West-Muren) crosscut continental flood basalts in the Antarctic extension of the ~ 180 Ma Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. The dikes exhibit unusual geochemical profi...
Published in: | Contributions to Mineralogy and Petrology |
---|---|
Main Authors: | , , , , |
Other Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Springer Science and Business Media LLC
2021
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1007/s00410-021-01777-6 https://link.springer.com/content/pdf/10.1007/s00410-021-01777-6.pdf https://link.springer.com/article/10.1007/s00410-021-01777-6/fulltext.html |
id |
crspringernat:10.1007/s00410-021-01777-6 |
---|---|
record_format |
openpolar |
spelling |
crspringernat:10.1007/s00410-021-01777-6 2023-05-15T14:10:53+02:00 Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province Heinonen, Jussi S. Luttinen, Arto V. Spera, Frank J. Vuori, Saku K. Bohrson, Wendy A. Luonnontieteiden ja Tekniikan Tutkimuksen Toimikunta University of Helsinki including Helsinki University Central Hospital 2021 http://dx.doi.org/10.1007/s00410-021-01777-6 https://link.springer.com/content/pdf/10.1007/s00410-021-01777-6.pdf https://link.springer.com/article/10.1007/s00410-021-01777-6/fulltext.html en eng Springer Science and Business Media LLC https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 CC-BY Contributions to Mineralogy and Petrology volume 176, issue 4 ISSN 0010-7999 1432-0967 Geochemistry and Petrology Geophysics journal-article 2021 crspringernat https://doi.org/10.1007/s00410-021-01777-6 2022-01-04T10:24:44Z Abstract Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 m (West-Muren) crosscut continental flood basalts in the Antarctic extension of the ~ 180 Ma Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. The dikes exhibit unusual geochemical profiles; most significantly, initial (at 180 Ma) ε Nd values increase from the dike interiors towards the hornfelsed wallrock basalts (from − 15.3 to − 7.8 in East-Muren and more gradually from − 9.0 to − 5.5 in West-Muren). In this study, we utilize models of partial melting and energy-constrained assimilation‒fractional crystallization in deciphering the magmatic evolution of the dikes and their contact aureoles. The modeling indicates that both gabbroic dikes acquired the distinctly negative ε Nd values recorded by their central parts by varying degrees of assimilation of Archean crust at depth. This first phase of deep contamination was followed by a second event at or close to the emplacement level and is related to the interaction of the magmas with the wallrock basalts. These basalts belong to a distinct Karoo LIP magma type having initial ε Nd from − 2.1 to + 2.5, which provides a stark contrast to the ε Nd composition of the dike parental magmas (− 15.3 for East-Muren, − 9.0 for West-Muren) previously contaminated by Archean crust. For East-Muren, the distal hornfelses represent partially melted wallrock basalts and the proximal contact zones represent hybrids of such residues with differentiated melts from the intrusion; the magmas that were contaminated by the partial melts of the wallrock basalts were likely transported away from the currently exposed parts of the conduit before the magma–wallrock contact was sealed and further assimilation prevented. In contrast, for West-Muren, the assimilation of the wallrock basalt partial melts is recorded by the gradually increasing ε Nd of the presently exposed gabbroic rocks towards the roof contact with the basalts. Our study shows that primitive LIP magmas release enough sensible and latent heat to partially melt and potentially assimilate wallrocks in multiple stages. This type of multi-stage assimilation is difficult to detect in general, especially if the associated wallrocks show broad compositional similarity with the intruding magmas. Notably, trace element and isotopic heterogeneity in LIP magmas can be homogenized by such processes (basaltic cannibalism). If similar processes work at larger scales, they may affect the geochemical evolution of the crust and influence the generation of, for example, massif-type anorthosites and “ghost plagioclase” geochemical signature. Article in Journal/Newspaper Antarc* Antarctic Dronning Maud Land Springer Nature (via Crossref) Antarctic Dronning Maud Land Muren ENVELOPE(-15.000,-15.000,-73.733,-73.733) The Antarctic Vestfjella ENVELOPE(-14.000,-14.000,-73.167,-73.167) Contributions to Mineralogy and Petrology 176 4 |
institution |
Open Polar |
collection |
Springer Nature (via Crossref) |
op_collection_id |
crspringernat |
language |
English |
topic |
Geochemistry and Petrology Geophysics |
spellingShingle |
Geochemistry and Petrology Geophysics Heinonen, Jussi S. Luttinen, Arto V. Spera, Frank J. Vuori, Saku K. Bohrson, Wendy A. Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province |
topic_facet |
Geochemistry and Petrology Geophysics |
description |
Abstract Two subvertical gabbroic dikes with widths of ~ 350 m (East-Muren) and ≥ 500 m (West-Muren) crosscut continental flood basalts in the Antarctic extension of the ~ 180 Ma Karoo large igneous province (LIP) in Vestfjella, western Dronning Maud Land. The dikes exhibit unusual geochemical profiles; most significantly, initial (at 180 Ma) ε Nd values increase from the dike interiors towards the hornfelsed wallrock basalts (from − 15.3 to − 7.8 in East-Muren and more gradually from − 9.0 to − 5.5 in West-Muren). In this study, we utilize models of partial melting and energy-constrained assimilation‒fractional crystallization in deciphering the magmatic evolution of the dikes and their contact aureoles. The modeling indicates that both gabbroic dikes acquired the distinctly negative ε Nd values recorded by their central parts by varying degrees of assimilation of Archean crust at depth. This first phase of deep contamination was followed by a second event at or close to the emplacement level and is related to the interaction of the magmas with the wallrock basalts. These basalts belong to a distinct Karoo LIP magma type having initial ε Nd from − 2.1 to + 2.5, which provides a stark contrast to the ε Nd composition of the dike parental magmas (− 15.3 for East-Muren, − 9.0 for West-Muren) previously contaminated by Archean crust. For East-Muren, the distal hornfelses represent partially melted wallrock basalts and the proximal contact zones represent hybrids of such residues with differentiated melts from the intrusion; the magmas that were contaminated by the partial melts of the wallrock basalts were likely transported away from the currently exposed parts of the conduit before the magma–wallrock contact was sealed and further assimilation prevented. In contrast, for West-Muren, the assimilation of the wallrock basalt partial melts is recorded by the gradually increasing ε Nd of the presently exposed gabbroic rocks towards the roof contact with the basalts. Our study shows that primitive LIP magmas release enough sensible and latent heat to partially melt and potentially assimilate wallrocks in multiple stages. This type of multi-stage assimilation is difficult to detect in general, especially if the associated wallrocks show broad compositional similarity with the intruding magmas. Notably, trace element and isotopic heterogeneity in LIP magmas can be homogenized by such processes (basaltic cannibalism). If similar processes work at larger scales, they may affect the geochemical evolution of the crust and influence the generation of, for example, massif-type anorthosites and “ghost plagioclase” geochemical signature. |
author2 |
Luonnontieteiden ja Tekniikan Tutkimuksen Toimikunta University of Helsinki including Helsinki University Central Hospital |
format |
Article in Journal/Newspaper |
author |
Heinonen, Jussi S. Luttinen, Arto V. Spera, Frank J. Vuori, Saku K. Bohrson, Wendy A. |
author_facet |
Heinonen, Jussi S. Luttinen, Arto V. Spera, Frank J. Vuori, Saku K. Bohrson, Wendy A. |
author_sort |
Heinonen, Jussi S. |
title |
Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province |
title_short |
Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province |
title_full |
Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province |
title_fullStr |
Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province |
title_full_unstemmed |
Serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the Antarctic extension of the Karoo large igneous province |
title_sort |
serial interaction of primitive magmas with felsic and mafic crust recorded by gabbroic dikes from the antarctic extension of the karoo large igneous province |
publisher |
Springer Science and Business Media LLC |
publishDate |
2021 |
url |
http://dx.doi.org/10.1007/s00410-021-01777-6 https://link.springer.com/content/pdf/10.1007/s00410-021-01777-6.pdf https://link.springer.com/article/10.1007/s00410-021-01777-6/fulltext.html |
long_lat |
ENVELOPE(-15.000,-15.000,-73.733,-73.733) ENVELOPE(-14.000,-14.000,-73.167,-73.167) |
geographic |
Antarctic Dronning Maud Land Muren The Antarctic Vestfjella |
geographic_facet |
Antarctic Dronning Maud Land Muren The Antarctic Vestfjella |
genre |
Antarc* Antarctic Dronning Maud Land |
genre_facet |
Antarc* Antarctic Dronning Maud Land |
op_source |
Contributions to Mineralogy and Petrology volume 176, issue 4 ISSN 0010-7999 1432-0967 |
op_rights |
https://creativecommons.org/licenses/by/4.0 https://creativecommons.org/licenses/by/4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1007/s00410-021-01777-6 |
container_title |
Contributions to Mineralogy and Petrology |
container_volume |
176 |
container_issue |
4 |
_version_ |
1766283004195373056 |