Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador
The early middle Archaean Maggo gneisses of the southern Nain Province, Labrador, form the southwest portion of the once contiguous North Atlantic (Nutak) Craton (NAC). The gneisses and their late middle Archaean metamorphosed and migmatized equivalents are typical of grey gneiss terranes exposed wo...
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crcansciencepubl:10.1139/e91-005 2023-12-17T10:33:32+01:00 Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador Finn, Gregory C. 1991 http://dx.doi.org/10.1139/e91-005 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-005 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 28, issue 1, page 44-57 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1991 crcansciencepubl https://doi.org/10.1139/e91-005 2023-11-19T13:38:30Z The early middle Archaean Maggo gneisses of the southern Nain Province, Labrador, form the southwest portion of the once contiguous North Atlantic (Nutak) Craton (NAC). The gneisses and their late middle Archaean metamorphosed and migmatized equivalents are typical of grey gneiss terranes exposed worldwide. Geochemically the gneisses exhibit a continuous range of composition from 53.7 to 78.4 wt.% SiO 2 and straddle the boundary between low- and high-Al trondhjemites. Major-element distributions are comparable to those of other Archaean-aged NAC gneisses (Amîtsoq, Uivak, and Nûk gneisses), however, the Na 2 O and K 2 O contents are scattered. The gneisses are depleted in K, Rb, and Ba, are enriched in Sr, and have high-field-strength-element distributions similar to those for NAC gneisses.Rare-earth-element (REE) patterns of Maggo gneisses can be subdivided, on the basis of the nature of the Eu anomaly, into two groups of samples: (i) with negative Eu anomalies and higher Σ REE contents and (ii) with positive to normal Eu anomalies and lower Σ REE contents. The subdivision reflects differentiation processes in the parent magma of the Maggo gneisses. REE patterns are similar to those reported for NAC grey gneiss complexes. On the basis of the (La/Yb) N and (Yb) N values, the Maggo gneisses parent magma is interpreted as being derived by partial-melting processes from preexisting, high-grade (granulite to amphibolite facies) sialic continental crust equivalent to the early Archaean lithologies preserved elsewhere in the NAC. Article in Journal/Newspaper Nain North Atlantic Canadian Science Publishing (via Crossref) Nain ENVELOPE(-61.695,-61.695,56.542,56.542) Amîtsoq ENVELOPE(-51.472,-51.472,64.080,64.080) Nutak ENVELOPE(-61.865,-61.865,57.467,57.467) Canadian Journal of Earth Sciences 28 1 44 57 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Finn, Gregory C. Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador |
topic_facet |
General Earth and Planetary Sciences |
description |
The early middle Archaean Maggo gneisses of the southern Nain Province, Labrador, form the southwest portion of the once contiguous North Atlantic (Nutak) Craton (NAC). The gneisses and their late middle Archaean metamorphosed and migmatized equivalents are typical of grey gneiss terranes exposed worldwide. Geochemically the gneisses exhibit a continuous range of composition from 53.7 to 78.4 wt.% SiO 2 and straddle the boundary between low- and high-Al trondhjemites. Major-element distributions are comparable to those of other Archaean-aged NAC gneisses (Amîtsoq, Uivak, and Nûk gneisses), however, the Na 2 O and K 2 O contents are scattered. The gneisses are depleted in K, Rb, and Ba, are enriched in Sr, and have high-field-strength-element distributions similar to those for NAC gneisses.Rare-earth-element (REE) patterns of Maggo gneisses can be subdivided, on the basis of the nature of the Eu anomaly, into two groups of samples: (i) with negative Eu anomalies and higher Σ REE contents and (ii) with positive to normal Eu anomalies and lower Σ REE contents. The subdivision reflects differentiation processes in the parent magma of the Maggo gneisses. REE patterns are similar to those reported for NAC grey gneiss complexes. On the basis of the (La/Yb) N and (Yb) N values, the Maggo gneisses parent magma is interpreted as being derived by partial-melting processes from preexisting, high-grade (granulite to amphibolite facies) sialic continental crust equivalent to the early Archaean lithologies preserved elsewhere in the NAC. |
format |
Article in Journal/Newspaper |
author |
Finn, Gregory C. |
author_facet |
Finn, Gregory C. |
author_sort |
Finn, Gregory C. |
title |
Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador |
title_short |
Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador |
title_full |
Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador |
title_fullStr |
Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador |
title_full_unstemmed |
Major-, trace-, and rare-earth-element geochemistry of the Archaean Maggo gneisses, southern Nain Province, Labrador |
title_sort |
major-, trace-, and rare-earth-element geochemistry of the archaean maggo gneisses, southern nain province, labrador |
publisher |
Canadian Science Publishing |
publishDate |
1991 |
url |
http://dx.doi.org/10.1139/e91-005 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-005 |
long_lat |
ENVELOPE(-61.695,-61.695,56.542,56.542) ENVELOPE(-51.472,-51.472,64.080,64.080) ENVELOPE(-61.865,-61.865,57.467,57.467) |
geographic |
Nain Amîtsoq Nutak |
geographic_facet |
Nain Amîtsoq Nutak |
genre |
Nain North Atlantic |
genre_facet |
Nain North Atlantic |
op_source |
Canadian Journal of Earth Sciences volume 28, issue 1, page 44-57 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e91-005 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
28 |
container_issue |
1 |
container_start_page |
44 |
op_container_end_page |
57 |
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1785587632739188736 |