Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica)
Palaeomagnetic investigations and Rb-Sr dating were carried out on samples from two plutons from the Granite Harbour Intrusives of the Transantarctic Mountains inland of Terra Nova Bay. The Rb-Sr whole rock-biotite ages from Teall Nunatak (475±4, 483±4 Ma), a quartz-diorite pluton cropping out to th...
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fthighwire:oai:open-archive.highwire.org:gji:135/3/1019 2023-05-15T14:03:03+02:00 Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) Lanza, Roberto Tonarini, Sonia 1998-12-01 00:00:00.0 text/html http://gji.oxfordjournals.org/cgi/content/short/135/3/1019 https://doi.org/10.1046/j.1365-246X.1998.00692.x en eng Oxford University Press http://gji.oxfordjournals.org/cgi/content/short/135/3/1019 http://dx.doi.org/10.1046/j.1365-246X.1998.00692.x Copyright (C) 1998, Oxford University Press Articles TEXT 1998 fthighwire https://doi.org/10.1046/j.1365-246X.1998.00692.x 2015-02-28T22:00:50Z Palaeomagnetic investigations and Rb-Sr dating were carried out on samples from two plutons from the Granite Harbour Intrusives of the Transantarctic Mountains inland of Terra Nova Bay. The Rb-Sr whole rock-biotite ages from Teall Nunatak (475±4, 483±4 Ma), a quartz-diorite pluton cropping out to the south of Priestley Glacier, are older than that from the Mount Keinath monzogranite (450±4 Ma), which is located to the north of the glacier. These results are consistent with the literature data, which suggest that during the last phases of the Ross Orogeny the cooling rate of the basement was significantly lower to the north than to the south of Priestley Glacier. The Teall Nunatak quartz-diorite is characterized by a stable magnetization, whose blocking-temperature spectrum ranges from 530 to 570°C. At one site, the stable magnetization is screened by a large secondary component of opposite polarity, removed by thermal demagnetization below 300°C. The characteristic directions after thermal demagnetization yielded a southern pole located at lat. 11°S, long. 21°E. The magnetization of Mount Keinath monzogranite consists of several components with overlapping stability spectra. A characteristic direction was isolated at one site only, obtained by demagnetizing the specimens in the temperature range from 380 to 460°C. Comparison with the other East Antarctica poles shows that those from Victoria Land are very well grouped and give a reliable early Ordovician palaeopole (lat. 5°S, long. 23°E, with K =196 and A 95 =3.7°), whereas the poles from Wilkes, Enderby and Dronning Maud Land are dispersed. We tentatively advance the hypothesis that the dispersion reflects different magnetization ages due to the slow cooling of these regions during the last stages of the Ross Orogeny. Text Antarc* Antarctica Dronning Maud Land East Antarctica Priestley Glacier Victoria Land HighWire Press (Stanford University) East Antarctica Dronning Maud Land Victoria Land Terra Nova Bay Transantarctic Mountains Priestley ENVELOPE(161.883,161.883,-75.183,-75.183) Granite Harbour ENVELOPE(162.733,162.733,-76.883,-76.883) Priestley Glacier ENVELOPE(163.367,163.367,-74.333,-74.333) Keinath ENVELOPE(163.950,163.950,-74.533,-74.533) Mount Keinath ENVELOPE(163.950,163.950,-74.533,-74.533) Teall Nunatak ENVELOPE(162.550,162.550,-74.500,-74.500) Geophysical Journal International 135 3 1019 1027 |
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HighWire Press (Stanford University) |
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English |
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Articles |
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Articles Lanza, Roberto Tonarini, Sonia Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) |
topic_facet |
Articles |
description |
Palaeomagnetic investigations and Rb-Sr dating were carried out on samples from two plutons from the Granite Harbour Intrusives of the Transantarctic Mountains inland of Terra Nova Bay. The Rb-Sr whole rock-biotite ages from Teall Nunatak (475±4, 483±4 Ma), a quartz-diorite pluton cropping out to the south of Priestley Glacier, are older than that from the Mount Keinath monzogranite (450±4 Ma), which is located to the north of the glacier. These results are consistent with the literature data, which suggest that during the last phases of the Ross Orogeny the cooling rate of the basement was significantly lower to the north than to the south of Priestley Glacier. The Teall Nunatak quartz-diorite is characterized by a stable magnetization, whose blocking-temperature spectrum ranges from 530 to 570°C. At one site, the stable magnetization is screened by a large secondary component of opposite polarity, removed by thermal demagnetization below 300°C. The characteristic directions after thermal demagnetization yielded a southern pole located at lat. 11°S, long. 21°E. The magnetization of Mount Keinath monzogranite consists of several components with overlapping stability spectra. A characteristic direction was isolated at one site only, obtained by demagnetizing the specimens in the temperature range from 380 to 460°C. Comparison with the other East Antarctica poles shows that those from Victoria Land are very well grouped and give a reliable early Ordovician palaeopole (lat. 5°S, long. 23°E, with K =196 and A 95 =3.7°), whereas the poles from Wilkes, Enderby and Dronning Maud Land are dispersed. We tentatively advance the hypothesis that the dispersion reflects different magnetization ages due to the slow cooling of these regions during the last stages of the Ross Orogeny. |
format |
Text |
author |
Lanza, Roberto Tonarini, Sonia |
author_facet |
Lanza, Roberto Tonarini, Sonia |
author_sort |
Lanza, Roberto |
title |
Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) |
title_short |
Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) |
title_full |
Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) |
title_fullStr |
Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) |
title_full_unstemmed |
Palaeomagnetic and geochronological results from the Cambro-Ordovician Granite Harbour Intrusives inland of Terra Nova Bay (Victoria Land, Antarctica) |
title_sort |
palaeomagnetic and geochronological results from the cambro-ordovician granite harbour intrusives inland of terra nova bay (victoria land, antarctica) |
publisher |
Oxford University Press |
publishDate |
1998 |
url |
http://gji.oxfordjournals.org/cgi/content/short/135/3/1019 https://doi.org/10.1046/j.1365-246X.1998.00692.x |
long_lat |
ENVELOPE(161.883,161.883,-75.183,-75.183) ENVELOPE(162.733,162.733,-76.883,-76.883) ENVELOPE(163.367,163.367,-74.333,-74.333) ENVELOPE(163.950,163.950,-74.533,-74.533) ENVELOPE(163.950,163.950,-74.533,-74.533) ENVELOPE(162.550,162.550,-74.500,-74.500) |
geographic |
East Antarctica Dronning Maud Land Victoria Land Terra Nova Bay Transantarctic Mountains Priestley Granite Harbour Priestley Glacier Keinath Mount Keinath Teall Nunatak |
geographic_facet |
East Antarctica Dronning Maud Land Victoria Land Terra Nova Bay Transantarctic Mountains Priestley Granite Harbour Priestley Glacier Keinath Mount Keinath Teall Nunatak |
genre |
Antarc* Antarctica Dronning Maud Land East Antarctica Priestley Glacier Victoria Land |
genre_facet |
Antarc* Antarctica Dronning Maud Land East Antarctica Priestley Glacier Victoria Land |
op_relation |
http://gji.oxfordjournals.org/cgi/content/short/135/3/1019 http://dx.doi.org/10.1046/j.1365-246X.1998.00692.x |
op_rights |
Copyright (C) 1998, Oxford University Press |
op_doi |
https://doi.org/10.1046/j.1365-246X.1998.00692.x |
container_title |
Geophysical Journal International |
container_volume |
135 |
container_issue |
3 |
container_start_page |
1019 |
op_container_end_page |
1027 |
_version_ |
1766273532682043392 |