Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland
Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent re...
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/319753 2024-06-23T07:54:29+00:00 Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland Massiivi-tyypin anortosiittien jäännössulien tasapainoinen kiteytyminen: tapaustutkimus 1.64 miljardia vuotta vanhasta Ahvenisto-kompleksista Kaakkois-Suomessa Fred, Riikka Heinonen, Aku Heinonen, Jussi S. Petrology and Geochemistry Department of Geosciences and Geography Doctoral Programme in Geosciences 2020-10-01T13:17:01Z 23 application/pdf http://hdl.handle.net/10138/319753 eng eng Springer 10.1007/s00410-020-01726-9 SUOMEN AKATEMIA Fred , R , Heinonen , A & Heinonen , J S 2020 , ' Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland ' , Contributions to Mineralogy and Petrology , vol. 175 , no. 9 , 86 . https://doi.org/10.1007/s00410-020-01726-9 ORCID: /0000-0002-4549-9082/work/81360208 ORCID: /0000-0001-6650-4146/work/81360525 ORCID: /0000-0001-8998-4357/work/160774815 http://hdl.handle.net/10138/319753 685a32a4-8c69-442e-a118-9862cf9fd69d 000566960400002 cc_by info:eu-repo/semantics/openAccess openAccess Geosciences Massif-type anorthosites Monzodiorites Mineral-melt equilibrium Crystallization modeling RAPAKIVI GRANITE BATHOLITH UPPER-MANTLE STRUCTURE PROTEROZOIC ANORTHOSITE ADIRONDACK MOUNTAINS LARAMIE ANORTHOSITE LOFOTEN ISLANDS TRACE-ELEMENTS AMCG COMPLEX RICH ROCKS OXIDE-RICH Article publishedVersion 2020 ftunivhelsihelda 2024-06-04T14:34:43Z Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex, SE Finland, monzodioritic rocks occur as minor dike-like lenses closely associated with anorthositic rocks. We report new field, petrographic, and geochemical (XRF, ICP-MS, EMPA) data complemented with crystallization modeling (rhyolite-MELTS, MAGFRAC) for the monzodioritic rocks, apatite–oxide–gabbronorite, and olivine-bearing anorthositic rocks of the Ahvenisto complex. The presented evidence suggest that the monzodioritic rocks closely represent melt compositions while the apatite–oxide–gabbronorite and olivine-bearing anorthositic rocks are cumulates. The monzodioritic rocks seem to form a liquid line of descent (LLD) from primitive olivine monzodiorites to more evolved monzodiorites. Petrological modeling suggests that the interpreted LLD closely corresponds to a residual melt trend left after fractional crystallization (FC) and formation of the cumulate anorthositic rocks and minor apatite–oxide–gabbronorite in shallow magma chambers. Consequent equilibrium crystallization (EC) of separate monzodioritic residual magma batches can produce the observed mineral assemblages and the low Mg numbers measured from olivine (Fo25–45) and pyroxenes (En48–63, Mg#cpx 60–69). The monzodioritic rocks and apatite–oxide–gabbronorites show similar petrological and geochemical characteristics to corresponding rock types in other AMCG suites, and the model described in this study could be applicable to them as well. Peer reviewed Article in Journal/Newspaper Lofoten HELDA – University of Helsinki Open Repository Lofoten Contributions to Mineralogy and Petrology 175 9 |
institution |
Open Polar |
collection |
HELDA – University of Helsinki Open Repository |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
Geosciences Massif-type anorthosites Monzodiorites Mineral-melt equilibrium Crystallization modeling RAPAKIVI GRANITE BATHOLITH UPPER-MANTLE STRUCTURE PROTEROZOIC ANORTHOSITE ADIRONDACK MOUNTAINS LARAMIE ANORTHOSITE LOFOTEN ISLANDS TRACE-ELEMENTS AMCG COMPLEX RICH ROCKS OXIDE-RICH |
spellingShingle |
Geosciences Massif-type anorthosites Monzodiorites Mineral-melt equilibrium Crystallization modeling RAPAKIVI GRANITE BATHOLITH UPPER-MANTLE STRUCTURE PROTEROZOIC ANORTHOSITE ADIRONDACK MOUNTAINS LARAMIE ANORTHOSITE LOFOTEN ISLANDS TRACE-ELEMENTS AMCG COMPLEX RICH ROCKS OXIDE-RICH Fred, Riikka Heinonen, Aku Heinonen, Jussi S. Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland |
topic_facet |
Geosciences Massif-type anorthosites Monzodiorites Mineral-melt equilibrium Crystallization modeling RAPAKIVI GRANITE BATHOLITH UPPER-MANTLE STRUCTURE PROTEROZOIC ANORTHOSITE ADIRONDACK MOUNTAINS LARAMIE ANORTHOSITE LOFOTEN ISLANDS TRACE-ELEMENTS AMCG COMPLEX RICH ROCKS OXIDE-RICH |
description |
Fe–Ti–P-rich mafic to intermediate rocks (monzodiorites and oxide–apatite–gabbronorites, OAGNs) are found as small intrusions in most AMCG (anorthosite–magnerite–charnokite–granite) suites. The origin of the monzodioritic rocks is still debated, but in many studies, they are presumed to represent residual liquid compositions after fractionation of anorthositic cumulates. In the 1.64 Ga Ahvenisto complex, SE Finland, monzodioritic rocks occur as minor dike-like lenses closely associated with anorthositic rocks. We report new field, petrographic, and geochemical (XRF, ICP-MS, EMPA) data complemented with crystallization modeling (rhyolite-MELTS, MAGFRAC) for the monzodioritic rocks, apatite–oxide–gabbronorite, and olivine-bearing anorthositic rocks of the Ahvenisto complex. The presented evidence suggest that the monzodioritic rocks closely represent melt compositions while the apatite–oxide–gabbronorite and olivine-bearing anorthositic rocks are cumulates. The monzodioritic rocks seem to form a liquid line of descent (LLD) from primitive olivine monzodiorites to more evolved monzodiorites. Petrological modeling suggests that the interpreted LLD closely corresponds to a residual melt trend left after fractional crystallization (FC) and formation of the cumulate anorthositic rocks and minor apatite–oxide–gabbronorite in shallow magma chambers. Consequent equilibrium crystallization (EC) of separate monzodioritic residual magma batches can produce the observed mineral assemblages and the low Mg numbers measured from olivine (Fo25–45) and pyroxenes (En48–63, Mg#cpx 60–69). The monzodioritic rocks and apatite–oxide–gabbronorites show similar petrological and geochemical characteristics to corresponding rock types in other AMCG suites, and the model described in this study could be applicable to them as well. Peer reviewed |
author2 |
Petrology and Geochemistry Department of Geosciences and Geography Doctoral Programme in Geosciences |
format |
Article in Journal/Newspaper |
author |
Fred, Riikka Heinonen, Aku Heinonen, Jussi S. |
author_facet |
Fred, Riikka Heinonen, Aku Heinonen, Jussi S. |
author_sort |
Fred, Riikka |
title |
Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland |
title_short |
Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland |
title_full |
Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland |
title_fullStr |
Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland |
title_full_unstemmed |
Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland |
title_sort |
equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 ga ahvenisto complex, southeastern finland |
publisher |
Springer |
publishDate |
2020 |
url |
http://hdl.handle.net/10138/319753 |
geographic |
Lofoten |
geographic_facet |
Lofoten |
genre |
Lofoten |
genre_facet |
Lofoten |
op_relation |
10.1007/s00410-020-01726-9 SUOMEN AKATEMIA Fred , R , Heinonen , A & Heinonen , J S 2020 , ' Equilibrium crystallization of massif-type anorthosite residual melts: a case study from the 1.64 Ga Ahvenisto complex, Southeastern Finland ' , Contributions to Mineralogy and Petrology , vol. 175 , no. 9 , 86 . https://doi.org/10.1007/s00410-020-01726-9 ORCID: /0000-0002-4549-9082/work/81360208 ORCID: /0000-0001-6650-4146/work/81360525 ORCID: /0000-0001-8998-4357/work/160774815 http://hdl.handle.net/10138/319753 685a32a4-8c69-442e-a118-9862cf9fd69d 000566960400002 |
op_rights |
cc_by info:eu-repo/semantics/openAccess openAccess |
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