New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen
Abstract Palaeomagnetic-petrographic-structural analyses of Proterozoic–Lower Palaeozoic metamorphosed carbonates from 12 locations within Oscar II Land (Western Spitsbergen) have been carried out to determine their usefulness in palaeogeographic reconstructions for Caledonian time. Structural analy...
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Walter de Gruyter GmbH
2014
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Online Access: | http://dx.doi.org/10.2478/popore-2014-0031 https://www.degruyter.com/view/j/popore.2014.35.issue-4/popore-2014-0031/popore-2014-0031.pdf |
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crdegruytopen:10.2478/popore-2014-0031 2023-05-15T17:54:07+02:00 New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen Michalski, Krzysztof Nejbert, Krzysztof Domańska−Siuda, Justyna Manby, Geoffrey 2014 http://dx.doi.org/10.2478/popore-2014-0031 https://www.degruyter.com/view/j/popore.2014.35.issue-4/popore-2014-0031/popore-2014-0031.pdf unknown Walter de Gruyter GmbH Polish Polar Research volume 35, issue 4 ISSN 2081-8262 journal-article 2014 crdegruytopen https://doi.org/10.2478/popore-2014-0031 2017-08-15T20:50:19Z Abstract Palaeomagnetic-petrographic-structural analyses of Proterozoic–Lower Palaeozoic metamorphosed carbonates from 12 locations within Oscar II Land (Western Spitsbergen) have been carried out to determine their usefulness in palaeogeographic reconstructions for Caledonian time. Structural analyses confirm that metacarbonates record several stages of deformation: D1, D2 ductile phases related to Caledonian metamorphism and a D3 brittle phase related to Late Cretaceous–Paleogene evolution of the West Spitsbergen Fold Belt. The latter is represented by thrust faults, localized folds with strain slip cleavages and late extensional collapse. Petrographic investigations reveal that Caledonian greenschist facies metamorphism was characterized by the high activity of H2O-CO2-rich fluids which promoted extensive recrystallization and within-rock spatial reorganization of sampled metacarbonates. Microscopic, SEM and microprobe analyses exclude the existence of any primary pre-metamorphic ferromagnetic minerals (primary-related to sedimentation and or early diagenesis) and point to metamorphic 4C superstructure (Fe7S8) pyrrhotite as the main ferromagnetic carrier in investigated rocks. This is confirmed by the three-component isothermal remanent magnetization (IRM) procedures and the results of thermal demagnetizations. In 12 sites a total number of 72 independently oriented palaeomagnetic samples were collected from which 181 specimens were drilled and thermally demagnetized. Sampled metacarbonates are weakly magnetized (NRM <0.2mA/m). The statistically significant palaeomagnetic results were achieved only from 1 of 12 investigated sites. In one site situated in the Western overturned limb of the Holmesletfjellet Syncline intermediate unblocking temperatures – “pyrrhotite related” component WTSJ5M superimposed on the S1 Caledonian schistosity was recognized (D = 100.7°, I = -21.4° α95% = 5.5°, k = 58.23). Coincidence of WTSJ5M with Silurian–Devonian sector of the Baltica reference path after unfolding of the syncline by the angle of 130° suggests synfolding origin of this direction. Further, this suggests that Holmesletfjellet Syncline originated as an open fold and has been transformed into an overturned syncline during the Late Caledonian shortening or in the Late Cretaceous–Palaeogene time. Article in Journal/Newspaper Oscar II Land Polar Research Spitsbergen Sciendo (de Gruyter - via CrossRef) Oscar II ENVELOPE(-62.500,-62.500,-65.750,-65.750) Oscar II Land ENVELOPE(13.299,13.299,78.441,78.441) Polish Polar Research 35 4 |
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Open Polar |
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Sciendo (de Gruyter - via CrossRef) |
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Abstract Palaeomagnetic-petrographic-structural analyses of Proterozoic–Lower Palaeozoic metamorphosed carbonates from 12 locations within Oscar II Land (Western Spitsbergen) have been carried out to determine their usefulness in palaeogeographic reconstructions for Caledonian time. Structural analyses confirm that metacarbonates record several stages of deformation: D1, D2 ductile phases related to Caledonian metamorphism and a D3 brittle phase related to Late Cretaceous–Paleogene evolution of the West Spitsbergen Fold Belt. The latter is represented by thrust faults, localized folds with strain slip cleavages and late extensional collapse. Petrographic investigations reveal that Caledonian greenschist facies metamorphism was characterized by the high activity of H2O-CO2-rich fluids which promoted extensive recrystallization and within-rock spatial reorganization of sampled metacarbonates. Microscopic, SEM and microprobe analyses exclude the existence of any primary pre-metamorphic ferromagnetic minerals (primary-related to sedimentation and or early diagenesis) and point to metamorphic 4C superstructure (Fe7S8) pyrrhotite as the main ferromagnetic carrier in investigated rocks. This is confirmed by the three-component isothermal remanent magnetization (IRM) procedures and the results of thermal demagnetizations. In 12 sites a total number of 72 independently oriented palaeomagnetic samples were collected from which 181 specimens were drilled and thermally demagnetized. Sampled metacarbonates are weakly magnetized (NRM <0.2mA/m). The statistically significant palaeomagnetic results were achieved only from 1 of 12 investigated sites. In one site situated in the Western overturned limb of the Holmesletfjellet Syncline intermediate unblocking temperatures – “pyrrhotite related” component WTSJ5M superimposed on the S1 Caledonian schistosity was recognized (D = 100.7°, I = -21.4° α95% = 5.5°, k = 58.23). Coincidence of WTSJ5M with Silurian–Devonian sector of the Baltica reference path after unfolding of the syncline by the angle of 130° suggests synfolding origin of this direction. Further, this suggests that Holmesletfjellet Syncline originated as an open fold and has been transformed into an overturned syncline during the Late Caledonian shortening or in the Late Cretaceous–Palaeogene time. |
format |
Article in Journal/Newspaper |
author |
Michalski, Krzysztof Nejbert, Krzysztof Domańska−Siuda, Justyna Manby, Geoffrey |
spellingShingle |
Michalski, Krzysztof Nejbert, Krzysztof Domańska−Siuda, Justyna Manby, Geoffrey New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen |
author_facet |
Michalski, Krzysztof Nejbert, Krzysztof Domańska−Siuda, Justyna Manby, Geoffrey |
author_sort |
Michalski, Krzysztof |
title |
New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen |
title_short |
New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen |
title_full |
New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen |
title_fullStr |
New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen |
title_full_unstemmed |
New palaeomagnetic data from metamorphosed carbonates of Western Oscar II Land, Western Spitsbergen |
title_sort |
new palaeomagnetic data from metamorphosed carbonates of western oscar ii land, western spitsbergen |
publisher |
Walter de Gruyter GmbH |
publishDate |
2014 |
url |
http://dx.doi.org/10.2478/popore-2014-0031 https://www.degruyter.com/view/j/popore.2014.35.issue-4/popore-2014-0031/popore-2014-0031.pdf |
long_lat |
ENVELOPE(-62.500,-62.500,-65.750,-65.750) ENVELOPE(13.299,13.299,78.441,78.441) |
geographic |
Oscar II Oscar II Land |
geographic_facet |
Oscar II Oscar II Land |
genre |
Oscar II Land Polar Research Spitsbergen |
genre_facet |
Oscar II Land Polar Research Spitsbergen |
op_source |
Polish Polar Research volume 35, issue 4 ISSN 2081-8262 |
op_doi |
https://doi.org/10.2478/popore-2014-0031 |
container_title |
Polish Polar Research |
container_volume |
35 |
container_issue |
4 |
_version_ |
1766161838613987328 |