Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen
Recent remapping and new age determinations has shed light on the understanding of Precambrian rocks northwest of Hornsund, southwest Spitsbergen. The Skålfjellet Subgroup has been regarded as the eastern equivalent of the Vimsodden Subgroup, and both of these occur within the Precambrian Eimfjellet...
Published in: | Polar Research |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Norwegian Polar Institute
1996
|
Subjects: | |
Online Access: | https://polarresearch.net/index.php/polar/article/view/1928 https://doi.org/10.3402/polar.v15i2.6645 |
id |
ftjpolarres:oai:journals.openacademia.net:article/1928 |
---|---|
record_format |
openpolar |
spelling |
ftjpolarres:oai:journals.openacademia.net:article/1928 2023-05-15T16:34:57+02:00 Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen Balašov, Yu. A. Peucat, J. J. Teben'kov, A. M. Ohta, Y. Larionov, A. N. Sirotkin, A. N. Bjornerud, M. 1996-01-12 application/pdf https://polarresearch.net/index.php/polar/article/view/1928 https://doi.org/10.3402/polar.v15i2.6645 eng eng Norwegian Polar Institute https://polarresearch.net/index.php/polar/article/view/1928/5177 https://polarresearch.net/index.php/polar/article/view/1928 doi:10.3402/polar.v15i2.6645 Copyright (c) 2018 Polar Research Polar Research; Vol. 15 No. 2 (1996); 167-181 1751-8369 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 1996 ftjpolarres https://doi.org/10.3402/polar.v15i2.6645 2021-11-11T19:11:42Z Recent remapping and new age determinations has shed light on the understanding of Precambrian rocks northwest of Hornsund, southwest Spitsbergen. The Skålfjellet Subgroup has been regarded as the eastern equivalent of the Vimsodden Subgroup, and both of these occur within the Precambrian Eimfjellet Group of southwest Spitsbergen. Although the Eimfjellet Group is considered to be older than the oldest unconformity in the area, the age of the rocks has not been known. The granitic-gabbroic rocks in the Skålfjellet Subgroup have been considered to be the products of granitisation for many years, but recent observations show that they are exotic blocks incorporated into the basic eruptive rocks which are the main constituents of the subgroup. These plutonic rocks have a wide range of compositions, from syenite via granite to gabbroic cumulates, which suggests the existence of a well-differentiated plutonic body at depth. U-Pb zircon and Pb evaporation datings yielded magmatic ages of ca. 1,100 to 1,200 Ma, and a conformable age has been obtained by Rb-Sr whole rock dating. Detrital zircons from the micaceous schists of the Isbjørnhamna Group, which underlies the Skålfjellet Subgroup, show a poorly defined discordia with an upper intercept age of ca. 2,200 Ma and a lower intercept age of ca. 360 Ma. These dating results define the magmatic age of the granitic-gabbroic rocks as late Mesoproterozoic, early Grenvillian. This age is in broad agreement with that of the metavolcanic rock clasts of the Pyttholmen meta-pyroclastic-conglomeratic unit at Vimsodden, which is considered to be the westernmost occurrence of the Skålfjellet Subgroup. A Rb-Sr whole rock age determination of the shaly phyllites from the Deilegga Group was performed in order to place constraints on the age of younger Precambrian event; however, no good isochron was obtained. Article in Journal/Newspaper Hornsund Isbjørnhamna Polar Research Spitsbergen Polar Research (E-Journal) Hornsund ENVELOPE(15.865,15.865,76.979,76.979) Isbjørnhamna ENVELOPE(15.603,15.603,77.002,77.002) Eimfjellet ENVELOPE(15.404,15.404,77.049,77.049) Deilegga ENVELOPE(15.518,15.518,77.066,77.066) Vimsodden ENVELOPE(15.041,15.041,77.109,77.109) Pyttholmen ENVELOPE(15.052,15.052,77.099,77.099) Skålfjellet ENVELOPE(15.473,15.473,77.044,77.044) Polar Research 15 2 167 181 |
institution |
Open Polar |
collection |
Polar Research (E-Journal) |
op_collection_id |
ftjpolarres |
language |
English |
description |
Recent remapping and new age determinations has shed light on the understanding of Precambrian rocks northwest of Hornsund, southwest Spitsbergen. The Skålfjellet Subgroup has been regarded as the eastern equivalent of the Vimsodden Subgroup, and both of these occur within the Precambrian Eimfjellet Group of southwest Spitsbergen. Although the Eimfjellet Group is considered to be older than the oldest unconformity in the area, the age of the rocks has not been known. The granitic-gabbroic rocks in the Skålfjellet Subgroup have been considered to be the products of granitisation for many years, but recent observations show that they are exotic blocks incorporated into the basic eruptive rocks which are the main constituents of the subgroup. These plutonic rocks have a wide range of compositions, from syenite via granite to gabbroic cumulates, which suggests the existence of a well-differentiated plutonic body at depth. U-Pb zircon and Pb evaporation datings yielded magmatic ages of ca. 1,100 to 1,200 Ma, and a conformable age has been obtained by Rb-Sr whole rock dating. Detrital zircons from the micaceous schists of the Isbjørnhamna Group, which underlies the Skålfjellet Subgroup, show a poorly defined discordia with an upper intercept age of ca. 2,200 Ma and a lower intercept age of ca. 360 Ma. These dating results define the magmatic age of the granitic-gabbroic rocks as late Mesoproterozoic, early Grenvillian. This age is in broad agreement with that of the metavolcanic rock clasts of the Pyttholmen meta-pyroclastic-conglomeratic unit at Vimsodden, which is considered to be the westernmost occurrence of the Skålfjellet Subgroup. A Rb-Sr whole rock age determination of the shaly phyllites from the Deilegga Group was performed in order to place constraints on the age of younger Precambrian event; however, no good isochron was obtained. |
format |
Article in Journal/Newspaper |
author |
Balašov, Yu. A. Peucat, J. J. Teben'kov, A. M. Ohta, Y. Larionov, A. N. Sirotkin, A. N. Bjornerud, M. |
spellingShingle |
Balašov, Yu. A. Peucat, J. J. Teben'kov, A. M. Ohta, Y. Larionov, A. N. Sirotkin, A. N. Bjornerud, M. Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen |
author_facet |
Balašov, Yu. A. Peucat, J. J. Teben'kov, A. M. Ohta, Y. Larionov, A. N. Sirotkin, A. N. Bjornerud, M. |
author_sort |
Balašov, Yu. A. |
title |
Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen |
title_short |
Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen |
title_full |
Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen |
title_fullStr |
Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen |
title_full_unstemmed |
Rb-Sr whole rock and U-Pb zircon datings of the granitic-gabbroic rocks from the Skålfjellet Subgroup, southwest Spitsbergen |
title_sort |
rb-sr whole rock and u-pb zircon datings of the granitic-gabbroic rocks from the skålfjellet subgroup, southwest spitsbergen |
publisher |
Norwegian Polar Institute |
publishDate |
1996 |
url |
https://polarresearch.net/index.php/polar/article/view/1928 https://doi.org/10.3402/polar.v15i2.6645 |
long_lat |
ENVELOPE(15.865,15.865,76.979,76.979) ENVELOPE(15.603,15.603,77.002,77.002) ENVELOPE(15.404,15.404,77.049,77.049) ENVELOPE(15.518,15.518,77.066,77.066) ENVELOPE(15.041,15.041,77.109,77.109) ENVELOPE(15.052,15.052,77.099,77.099) ENVELOPE(15.473,15.473,77.044,77.044) |
geographic |
Hornsund Isbjørnhamna Eimfjellet Deilegga Vimsodden Pyttholmen Skålfjellet |
geographic_facet |
Hornsund Isbjørnhamna Eimfjellet Deilegga Vimsodden Pyttholmen Skålfjellet |
genre |
Hornsund Isbjørnhamna Polar Research Spitsbergen |
genre_facet |
Hornsund Isbjørnhamna Polar Research Spitsbergen |
op_source |
Polar Research; Vol. 15 No. 2 (1996); 167-181 1751-8369 |
op_relation |
https://polarresearch.net/index.php/polar/article/view/1928/5177 https://polarresearch.net/index.php/polar/article/view/1928 doi:10.3402/polar.v15i2.6645 |
op_rights |
Copyright (c) 2018 Polar Research |
op_doi |
https://doi.org/10.3402/polar.v15i2.6645 |
container_title |
Polar Research |
container_volume |
15 |
container_issue |
2 |
container_start_page |
167 |
op_container_end_page |
181 |
_version_ |
1766025057746812928 |