The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R.
Sm-Nd, Pb-Pb and U-Pb isotopic results are presented for samples from the Pilgujärvi Suite of the Pechenga Series. Whole rock samples and clinopyroxenes of ferropicritic volcanics yield a Sm-Nd isochron age of 1990 ± 66 Ma with εNd + 1.6 ± 0.4. This age is also supported by the Pb-Pb data on ferropi...
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| Format: | Article |
| Language: | English |
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Geological Society of Finland
1990-12-01
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| Series: | Bulletin of the Geological Society of Finland |
| Subjects: | |
| Online Access: | http://www.geologinenseura.fi/bulletin/Volume62/sgs_bt_062_2_pages_123_133.pdf |
| _version_ | 1818057630541676544 |
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| author | E. Hanski H. Huhma V.F. Smolkin M. Vaasjoki |
| author_facet | E. Hanski H. Huhma V.F. Smolkin M. Vaasjoki |
| author_sort | E. Hanski |
| collection | DOAJ |
| description | Sm-Nd, Pb-Pb and U-Pb isotopic results are presented for samples from the Pilgujärvi Suite of the Pechenga Series. Whole rock samples and clinopyroxenes of ferropicritic volcanics yield a Sm-Nd isochron age of 1990 ± 66 Ma with εNd + 1.6 ± 0.4. This age is also supported by the Pb-Pb data on ferropicrites, although the Pb isotopic system was partly disturbed by secondary processes. One 90% concordant U-Pb zircon analysis from a felsic metasediment indicates a minimum age of 1970 Ma for the deposition. Our isotopic results along with previous geochemical data support the view that the ferropicritic volcanics and the Ni-bearing gabbro- wehrlite intrusions are coeval and have similar source characteristics. The calculated εNd (1990 Ma) value of + 1.6 suggests that the Pechenga ferropicrites previously had had a long-term depleted mantle source that experiended an enrichment event about 200 Ma before the melt extraction occurred. Comparison with the previously presented Sm-Nd data from northern Finland, Sweden and Norway reveals differences in initial Nd isotopic ratios, which suggests a prolonged geochemical heterogeneity in the early Proterozoic subcontinental mantle below the Baltic Shield. |
| first_indexed | 2024-12-10T12:47:47Z |
| format | Article |
| id | doaj.art-38cde9edf0f04e1a9ba525780b3655a8 |
| institution | Directory Open Access Journal |
| issn | 0367-5211 1799-4632 |
| language | English |
| last_indexed | 2024-12-10T12:47:47Z |
| publishDate | 1990-12-01 |
| publisher | Geological Society of Finland |
| record_format | Article |
| series | Bulletin of the Geological Society of Finland |
| spelling | doaj.art-38cde9edf0f04e1a9ba525780b3655a82022-12-22T01:48:21ZengGeological Society of FinlandBulletin of the Geological Society of Finland0367-52111799-46321990-12-0162212313310.17741/bgsf/62.2.003The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R.E. HanskiH. HuhmaV.F. SmolkinM. VaasjokiSm-Nd, Pb-Pb and U-Pb isotopic results are presented for samples from the Pilgujärvi Suite of the Pechenga Series. Whole rock samples and clinopyroxenes of ferropicritic volcanics yield a Sm-Nd isochron age of 1990 ± 66 Ma with εNd + 1.6 ± 0.4. This age is also supported by the Pb-Pb data on ferropicrites, although the Pb isotopic system was partly disturbed by secondary processes. One 90% concordant U-Pb zircon analysis from a felsic metasediment indicates a minimum age of 1970 Ma for the deposition. Our isotopic results along with previous geochemical data support the view that the ferropicritic volcanics and the Ni-bearing gabbro- wehrlite intrusions are coeval and have similar source characteristics. The calculated εNd (1990 Ma) value of + 1.6 suggests that the Pechenga ferropicrites previously had had a long-term depleted mantle source that experiended an enrichment event about 200 Ma before the melt extraction occurred. Comparison with the previously presented Sm-Nd data from northern Finland, Sweden and Norway reveals differences in initial Nd isotopic ratios, which suggests a prolonged geochemical heterogeneity in the early Proterozoic subcontinental mantle below the Baltic Shield.http://www.geologinenseura.fi/bulletin/Volume62/sgs_bt_062_2_pages_123_133.pdfmetavolcanic rockspicriteintrusionsabsolute ageSm/NdU/PbPb/PbProterozoicPechengaKola PeninsulaUSSR |
| spellingShingle | E. Hanski H. Huhma V.F. Smolkin M. Vaasjoki The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R. Bulletin of the Geological Society of Finland metavolcanic rocks picrite intrusions absolute age Sm/Nd U/Pb Pb/Pb Proterozoic Pechenga Kola Peninsula USSR |
| title | The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R. |
| title_full | The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R. |
| title_fullStr | The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R. |
| title_full_unstemmed | The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R. |
| title_short | The age of the ferropicritic volcanics and comagmatic Ni-bearing intrusions at Pechenga, Kola Peninsula, U.S.S.R. |
| title_sort | age of the ferropicritic volcanics and comagmatic ni bearing intrusions at pechenga kola peninsula u s s r |
| topic | metavolcanic rocks picrite intrusions absolute age Sm/Nd U/Pb Pb/Pb Proterozoic Pechenga Kola Peninsula USSR |
| url | http://www.geologinenseura.fi/bulletin/Volume62/sgs_bt_062_2_pages_123_133.pdf |
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