Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry
The mafic and ultramafic rocks in the Raisduoddar-Halti area constitute a shallow horizontal allochthonous plate in the highest tectono-stratigraphic position of the Finnish Caledonides. They are located close to the boundary of the lower part of the Vaddas Nappe in the Upper Allochthon and the Kala...
Published in: | Bulletin of the Geological Society of Finland |
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Geological Society of Finland
1991
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ftdoajarticles:oai:doaj.org/article:3738cfe3952346d2b9129059e629fd53 2023-05-15T16:06:13+02:00 Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry P. Sipilä 1991-06-01T00:00:00Z https://doi.org/10.17741/bgsf/63.1.002 https://doaj.org/article/3738cfe3952346d2b9129059e629fd53 EN eng Geological Society of Finland http://www.geologinenseura.fi/bulletin/Volume63/sgs_bt_063_1_pages_015_024.pdf https://doaj.org/toc/0367-5211 https://doaj.org/toc/1799-4632 doi:10.17741/bgsf/63.1.002 0367-5211 1799-4632 https://doaj.org/article/3738cfe3952346d2b9129059e629fd53 Bulletin of the Geological Society of Finland, Vol 63, Iss 1, Pp 15-24 (1991) gabbros sills cumulates chemical composition electron probe data caledonides Paleozoic Ridnitsohkka Enontekiö Finland Geology QE1-996.5 article 1991 ftdoajarticles https://doi.org/10.17741/bgsf/63.1.002 2022-12-30T21:42:56Z The mafic and ultramafic rocks in the Raisduoddar-Halti area constitute a shallow horizontal allochthonous plate in the highest tectono-stratigraphic position of the Finnish Caledonides. They are located close to the boundary of the lower part of the Vaddas Nappe in the Upper Allochthon and the Kalak Nappe Complex in the Middle Allochthon. The mafic and ultramafic rocks in the area are Ridnitsohkka gabbro sills in the east and dunite-troctolite-olivine gabbro cumulates at Raisduoddar- Halti. They are syngenetic and belong to the same nappe. The lower contact with the Nabar schists of the Kalak Nappe Complex on the cumulate side is distinctly tectonic and may continue as a tectonic contact in the sill area, too. The gabbro sills, which are tholeiitic in chemical composition, are enriched in LREE and show a small positive Eu anomaly. Close to the cumulate the gabbro sills contain olivine. The cumulate massif crystallized mainly as a closed system, as shown by the linear change in the composition of the rocks and minerals. The cumulates are intruded by coarse grained gabbro pegmatoids. The same pegmatoid magma gave rise to the metasomatic olivine gabbro with augite porphyroblasts between the cumulate massif and the sill area. Before last nappe movements the rocks of the cumulate massif were partly amphibolitized across the lithologic contacts and magmatic layering. As suggested by the total lithologic composition and the mineral composition, the magmatism in the area contains evidence of at least two major magmatic events. First, tholeiitic gabbro sills intruded the acid schists. Then, the magma type having become more primitive the Raisduoddar-Halti cumulates fractionated. A new U-Pb age of 434 ± 4 Ma on baddeleyite from Ridnitsohkka gabbro sills shows that the mafic and ultramafic rocks in the area can be correlated with the synorogenic Scandian mafic intrusive rocks in the Scandinavian Caledonides. Article in Journal/Newspaper Enontekiö Directory of Open Access Journals: DOAJ Articles Enontekiö ENVELOPE(23.632,23.632,68.386,68.386) Kalak ENVELOPE(27.055,27.055,70.611,70.611) Halti ENVELOPE(21.284,21.284,69.302,69.302) Bulletin of the Geological Society of Finland 63 1 15 24 |
institution |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
gabbros sills cumulates chemical composition electron probe data caledonides Paleozoic Ridnitsohkka Enontekiö Finland Geology QE1-996.5 |
spellingShingle |
gabbros sills cumulates chemical composition electron probe data caledonides Paleozoic Ridnitsohkka Enontekiö Finland Geology QE1-996.5 P. Sipilä Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry |
topic_facet |
gabbros sills cumulates chemical composition electron probe data caledonides Paleozoic Ridnitsohkka Enontekiö Finland Geology QE1-996.5 |
description |
The mafic and ultramafic rocks in the Raisduoddar-Halti area constitute a shallow horizontal allochthonous plate in the highest tectono-stratigraphic position of the Finnish Caledonides. They are located close to the boundary of the lower part of the Vaddas Nappe in the Upper Allochthon and the Kalak Nappe Complex in the Middle Allochthon. The mafic and ultramafic rocks in the area are Ridnitsohkka gabbro sills in the east and dunite-troctolite-olivine gabbro cumulates at Raisduoddar- Halti. They are syngenetic and belong to the same nappe. The lower contact with the Nabar schists of the Kalak Nappe Complex on the cumulate side is distinctly tectonic and may continue as a tectonic contact in the sill area, too. The gabbro sills, which are tholeiitic in chemical composition, are enriched in LREE and show a small positive Eu anomaly. Close to the cumulate the gabbro sills contain olivine. The cumulate massif crystallized mainly as a closed system, as shown by the linear change in the composition of the rocks and minerals. The cumulates are intruded by coarse grained gabbro pegmatoids. The same pegmatoid magma gave rise to the metasomatic olivine gabbro with augite porphyroblasts between the cumulate massif and the sill area. Before last nappe movements the rocks of the cumulate massif were partly amphibolitized across the lithologic contacts and magmatic layering. As suggested by the total lithologic composition and the mineral composition, the magmatism in the area contains evidence of at least two major magmatic events. First, tholeiitic gabbro sills intruded the acid schists. Then, the magma type having become more primitive the Raisduoddar-Halti cumulates fractionated. A new U-Pb age of 434 ± 4 Ma on baddeleyite from Ridnitsohkka gabbro sills shows that the mafic and ultramafic rocks in the area can be correlated with the synorogenic Scandian mafic intrusive rocks in the Scandinavian Caledonides. |
format |
Article in Journal/Newspaper |
author |
P. Sipilä |
author_facet |
P. Sipilä |
author_sort |
P. Sipilä |
title |
Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry |
title_short |
Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry |
title_full |
Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry |
title_fullStr |
Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry |
title_full_unstemmed |
Mafic and ultramafic igneous rocks of the Raisduoddar-Halti area in the Finnish-Norwegian Caledonides. Petrography, mineralogy and geochemistry |
title_sort |
mafic and ultramafic igneous rocks of the raisduoddar-halti area in the finnish-norwegian caledonides. petrography, mineralogy and geochemistry |
publisher |
Geological Society of Finland |
publishDate |
1991 |
url |
https://doi.org/10.17741/bgsf/63.1.002 https://doaj.org/article/3738cfe3952346d2b9129059e629fd53 |
long_lat |
ENVELOPE(23.632,23.632,68.386,68.386) ENVELOPE(27.055,27.055,70.611,70.611) ENVELOPE(21.284,21.284,69.302,69.302) |
geographic |
Enontekiö Kalak Halti |
geographic_facet |
Enontekiö Kalak Halti |
genre |
Enontekiö |
genre_facet |
Enontekiö |
op_source |
Bulletin of the Geological Society of Finland, Vol 63, Iss 1, Pp 15-24 (1991) |
op_relation |
http://www.geologinenseura.fi/bulletin/Volume63/sgs_bt_063_1_pages_015_024.pdf https://doaj.org/toc/0367-5211 https://doaj.org/toc/1799-4632 doi:10.17741/bgsf/63.1.002 0367-5211 1799-4632 https://doaj.org/article/3738cfe3952346d2b9129059e629fd53 |
op_doi |
https://doi.org/10.17741/bgsf/63.1.002 |
container_title |
Bulletin of the Geological Society of Finland |
container_volume |
63 |
container_issue |
1 |
container_start_page |
15 |
op_container_end_page |
24 |
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1766402122390175744 |