U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula
New geological mapping combined with U–Pb ion microprobe zircon geochronology on the isolated but locally extensive exposures of crystalline basement inliers of eastern Graham Land has greatly improved our understanding of the region’s early crustal evolution and has allowed a more thorough evaluati...
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ftnerc:oai:nora.nerc.ac.uk:18760 2023-05-15T13:45:12+02:00 U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula Riley, T. R. Flowerdew, M. J. Whitehouse, M. J. 2012 http://nora.nerc.ac.uk/id/eprint/18760/ http://jgs.geoscienceworld.org/content/169/4/381.abstract unknown Riley, T. R. orcid:0000-0002-3333-5021 Flowerdew, M. J.; Whitehouse, M. J. 2012 U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula. Journal of the Geological Society, 169 (4). 381-393. https://doi.org/10.1144/0016-76492011-142 <https://doi.org/10.1144/0016-76492011-142> Earth Sciences Publication - Article PeerReviewed 2012 ftnerc https://doi.org/10.1144/0016-76492011-142 2023-02-04T19:31:55Z New geological mapping combined with U–Pb ion microprobe zircon geochronology on the isolated but locally extensive exposures of crystalline basement inliers of eastern Graham Land has greatly improved our understanding of the region’s early crustal evolution and has allowed a more thorough evaluation of Patagonia–Antarctic Peninsula connections prior to Gondwana break-up. At Eden Glacier, diorite gneisses yield Early Ordovician protolith ages of 487 ± 3 and 485 ± 3 Ma and represent the oldest in situ rocks recorded on the Antarctic Peninsula, and indicate a significant spatial extension of Famatinian-age magmatism of Patagonia. Zircon overgrowths in the Early Ordovician protoliths and granitic leucosomes developed within them record two phases of Permian metamorphism at c. 275 and c. 257 Ma, coincident in part with diorite plutonism of the area at 272 ± 2 Ma. At Adie Inlet, granitic leucosomes from paragneiss have been dated at 276 ± 3 Ma, and these are in turn cut by 257 ± 3 Ma xenolith-rich diorite gneiss. The diorite intruded during a second phase of deformation, which folded the paragneiss leucosomes into tight folds. This whole assembly is cut by intensely brecciated megacrystic granodiorite, which yielded a 259 ± 3 Ma age. South of Cabinet Inlet a very different sequence of events is evident, with Triassic magmatism at c. 236 Ma extensive along the Joerg Peninsula. Migmatitic leucosomes are dated at c. 224 Ma and magmatism and deformation events apparently continued to c. 209 Ma at Cape Casey. Our data indicate that the Devonian and Carboniferous magmatism at Target Hill, considered to represent the ‘classic’ basement complex of the Antarctic Peninsula, is not representative regionally. The Target Hill crustal block contains a major break along Cabinet Inlet; to the north, Ordovician and Permian protoliths were variably migmatized during two episodes of Permian deformation and metamorphism, whereas to the south, Triassic protoliths and Triassic metamorphism are encountered. Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Graham Land Natural Environment Research Council: NERC Open Research Archive Antarctic The Antarctic Antarctic Peninsula Patagonia Graham Land ENVELOPE(-63.500,-63.500,-66.000,-66.000) Joerg ENVELOPE(-65.169,-65.169,-68.181,-68.181) Cabinet Inlet ENVELOPE(-63.500,-63.500,-66.250,-66.250) Adie ENVELOPE(-62.333,-62.333,-66.417,-66.417) Joerg peninsula ENVELOPE(-65.169,-65.169,-68.181,-68.181) Adie Inlet ENVELOPE(-62.315,-62.315,-66.338,-66.338) Cape Casey ENVELOPE(-64.254,-64.254,-64.730,-64.730) Target Hill ENVELOPE(-62.991,-62.991,-66.004,-66.004) Eden Glacier ENVELOPE(-63.250,-63.250,-66.200,-66.200) Journal of the Geological Society 169 4 381 393 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Riley, T. R. Flowerdew, M. J. Whitehouse, M. J. U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
topic_facet |
Earth Sciences |
description |
New geological mapping combined with U–Pb ion microprobe zircon geochronology on the isolated but locally extensive exposures of crystalline basement inliers of eastern Graham Land has greatly improved our understanding of the region’s early crustal evolution and has allowed a more thorough evaluation of Patagonia–Antarctic Peninsula connections prior to Gondwana break-up. At Eden Glacier, diorite gneisses yield Early Ordovician protolith ages of 487 ± 3 and 485 ± 3 Ma and represent the oldest in situ rocks recorded on the Antarctic Peninsula, and indicate a significant spatial extension of Famatinian-age magmatism of Patagonia. Zircon overgrowths in the Early Ordovician protoliths and granitic leucosomes developed within them record two phases of Permian metamorphism at c. 275 and c. 257 Ma, coincident in part with diorite plutonism of the area at 272 ± 2 Ma. At Adie Inlet, granitic leucosomes from paragneiss have been dated at 276 ± 3 Ma, and these are in turn cut by 257 ± 3 Ma xenolith-rich diorite gneiss. The diorite intruded during a second phase of deformation, which folded the paragneiss leucosomes into tight folds. This whole assembly is cut by intensely brecciated megacrystic granodiorite, which yielded a 259 ± 3 Ma age. South of Cabinet Inlet a very different sequence of events is evident, with Triassic magmatism at c. 236 Ma extensive along the Joerg Peninsula. Migmatitic leucosomes are dated at c. 224 Ma and magmatism and deformation events apparently continued to c. 209 Ma at Cape Casey. Our data indicate that the Devonian and Carboniferous magmatism at Target Hill, considered to represent the ‘classic’ basement complex of the Antarctic Peninsula, is not representative regionally. The Target Hill crustal block contains a major break along Cabinet Inlet; to the north, Ordovician and Permian protoliths were variably migmatized during two episodes of Permian deformation and metamorphism, whereas to the south, Triassic protoliths and Triassic metamorphism are encountered. |
format |
Article in Journal/Newspaper |
author |
Riley, T. R. Flowerdew, M. J. Whitehouse, M. J. |
author_facet |
Riley, T. R. Flowerdew, M. J. Whitehouse, M. J. |
author_sort |
Riley, T. R. |
title |
U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
title_short |
U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
title_full |
U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
title_fullStr |
U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
title_full_unstemmed |
U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
title_sort |
u–pb ion-microprobe zircon geochronology from the basement inliers of eastern graham land, antarctic peninsula |
publishDate |
2012 |
url |
http://nora.nerc.ac.uk/id/eprint/18760/ http://jgs.geoscienceworld.org/content/169/4/381.abstract |
long_lat |
ENVELOPE(-63.500,-63.500,-66.000,-66.000) ENVELOPE(-65.169,-65.169,-68.181,-68.181) ENVELOPE(-63.500,-63.500,-66.250,-66.250) ENVELOPE(-62.333,-62.333,-66.417,-66.417) ENVELOPE(-65.169,-65.169,-68.181,-68.181) ENVELOPE(-62.315,-62.315,-66.338,-66.338) ENVELOPE(-64.254,-64.254,-64.730,-64.730) ENVELOPE(-62.991,-62.991,-66.004,-66.004) ENVELOPE(-63.250,-63.250,-66.200,-66.200) |
geographic |
Antarctic The Antarctic Antarctic Peninsula Patagonia Graham Land Joerg Cabinet Inlet Adie Joerg peninsula Adie Inlet Cape Casey Target Hill Eden Glacier |
geographic_facet |
Antarctic The Antarctic Antarctic Peninsula Patagonia Graham Land Joerg Cabinet Inlet Adie Joerg peninsula Adie Inlet Cape Casey Target Hill Eden Glacier |
genre |
Antarc* Antarctic Antarctic Peninsula Graham Land |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Graham Land |
op_relation |
Riley, T. R. orcid:0000-0002-3333-5021 Flowerdew, M. J.; Whitehouse, M. J. 2012 U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula. Journal of the Geological Society, 169 (4). 381-393. https://doi.org/10.1144/0016-76492011-142 <https://doi.org/10.1144/0016-76492011-142> |
op_doi |
https://doi.org/10.1144/0016-76492011-142 |
container_title |
Journal of the Geological Society |
container_volume |
169 |
container_issue |
4 |
container_start_page |
381 |
op_container_end_page |
393 |
_version_ |
1766216764501262336 |