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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ftgeosoclonfig:oai:figshare.com:article/3453059 2023-05-15T13:33:01+02:00 U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula T. R. Riley M. J. Flowerdew M. J. Whitehouse 2016-06-21T11:06:22Z https://doi.org/10.6084/m9.figshare.3453059.v1 https://figshare.com/articles/U_Pb_ion-microprobe_zircon_geochronology_from_the_basement_inliers_of_eastern_Graham_Land_Antarctic_Peninsula/3453059 unknown doi:10.6084/m9.figshare.3453059.v1 https://figshare.com/articles/U_Pb_ion-microprobe_zircon_geochronology_from_the_basement_inliers_of_eastern_Graham_Land_Antarctic_Peninsula/3453059 CC BY 4.0 CC-BY Geology Ordovician protolith ages Antarctic Peninsula Graham Land magmatism Target Hill crustal block basement inliers Ma brecciated megacrystic granodiorite Cabinet Inlet Antarctic Peninsula New granitic leucosomes Dataset 2016 ftgeosoclonfig https://doi.org/10.6084/m9.figshare.3453059.v1 2020-02-21T07:24:31Z 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. Dataset Antarc* Antarctic Antarctic Peninsula Graham Land Geological Society of London: Figshare Adie ENVELOPE(-62.333,-62.333,-66.417,-66.417) Adie Inlet ENVELOPE(-62.315,-62.315,-66.338,-66.338) Antarctic Antarctic Peninsula Cabinet Inlet ENVELOPE(-63.500,-63.500,-66.250,-66.250) Cape Casey ENVELOPE(-64.254,-64.254,-64.730,-64.730) Eden Glacier ENVELOPE(-63.250,-63.250,-66.200,-66.200) Graham Land ENVELOPE(-63.500,-63.500,-66.000,-66.000) Joerg ENVELOPE(-65.169,-65.169,-68.181,-68.181) Joerg peninsula ENVELOPE(-65.169,-65.169,-68.181,-68.181) Patagonia Target Hill ENVELOPE(-62.991,-62.991,-66.004,-66.004) The Antarctic |
institution |
Open Polar |
collection |
Geological Society of London: Figshare |
op_collection_id |
ftgeosoclonfig |
language |
unknown |
topic |
Geology Ordovician protolith ages Antarctic Peninsula Graham Land magmatism Target Hill crustal block basement inliers Ma brecciated megacrystic granodiorite Cabinet Inlet Antarctic Peninsula New granitic leucosomes |
spellingShingle |
Geology Ordovician protolith ages Antarctic Peninsula Graham Land magmatism Target Hill crustal block basement inliers Ma brecciated megacrystic granodiorite Cabinet Inlet Antarctic Peninsula New granitic leucosomes T. R. Riley M. J. Flowerdew M. J. Whitehouse U–Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula |
topic_facet |
Geology Ordovician protolith ages Antarctic Peninsula Graham Land magmatism Target Hill crustal block basement inliers Ma brecciated megacrystic granodiorite Cabinet Inlet Antarctic Peninsula New granitic leucosomes |
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 |
Dataset |
author |
T. R. Riley M. J. Flowerdew M. J. Whitehouse |
author_facet |
T. R. Riley M. J. Flowerdew M. J. Whitehouse |
author_sort |
T. R. Riley |
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 |
2016 |
url |
https://doi.org/10.6084/m9.figshare.3453059.v1 https://figshare.com/articles/U_Pb_ion-microprobe_zircon_geochronology_from_the_basement_inliers_of_eastern_Graham_Land_Antarctic_Peninsula/3453059 |
long_lat |
ENVELOPE(-62.333,-62.333,-66.417,-66.417) ENVELOPE(-62.315,-62.315,-66.338,-66.338) ENVELOPE(-63.500,-63.500,-66.250,-66.250) ENVELOPE(-64.254,-64.254,-64.730,-64.730) ENVELOPE(-63.250,-63.250,-66.200,-66.200) ENVELOPE(-63.500,-63.500,-66.000,-66.000) ENVELOPE(-65.169,-65.169,-68.181,-68.181) ENVELOPE(-65.169,-65.169,-68.181,-68.181) ENVELOPE(-62.991,-62.991,-66.004,-66.004) |
geographic |
Adie Adie Inlet Antarctic Antarctic Peninsula Cabinet Inlet Cape Casey Eden Glacier Graham Land Joerg Joerg peninsula Patagonia Target Hill The Antarctic |
geographic_facet |
Adie Adie Inlet Antarctic Antarctic Peninsula Cabinet Inlet Cape Casey Eden Glacier Graham Land Joerg Joerg peninsula Patagonia Target Hill The Antarctic |
genre |
Antarc* Antarctic Antarctic Peninsula Graham Land |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Graham Land |
op_relation |
doi:10.6084/m9.figshare.3453059.v1 https://figshare.com/articles/U_Pb_ion-microprobe_zircon_geochronology_from_the_basement_inliers_of_eastern_Graham_Land_Antarctic_Peninsula/3453059 |
op_rights |
CC BY 4.0 |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.6084/m9.figshare.3453059.v1 |
_version_ |
1766037764483055616 |