Structural setting of the neo archean terrains in the Commonwealth Bay area (143°-145°E), Terre Adélie Craton, East Antarctica.

International audience Lithological and structural maps from the East Commonwealth Bay Unit (ECB; Terre Adélie and Georges V land, Antarctica) are presented with a summary of the main structural and metamorphic data obtained in the area. The ECB unit is structured during the Late Archean – Lower Pro...

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Bibliographic Details
Published in:Gondwana Research
Main Authors: Ménot, René-Pierre, Pecher, Arnaud, Rolland, Yan, Peucat, J.J., Pelletier, A., Duclaux, G., Guillot, Stéphane
Other Authors: Laboratoire Magmas et Volcans (LMV), Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS)
Format: Article in Journal/Newspaper
Language:English
Published: HAL CCSD 2005
Subjects:
Online Access:https://hal.science/hal-00103170
https://hal.science/hal-00103170/document
https://hal.science/hal-00103170/file/Menot_et_al._2005.pdf
https://doi.org/10.1016/S1342-937X(05)70258-6
Description
Summary:International audience Lithological and structural maps from the East Commonwealth Bay Unit (ECB; Terre Adélie and Georges V land, Antarctica) are presented with a summary of the main structural and metamorphic data obtained in the area. The ECB unit is structured during the Late Archean – Lower Proterozoic (at 2.4-2.5 Ga), with (i) granulite metamorphism at 9 - 6 kbar and 850 ± 50 °C of lower-mid crust and amphibolite metamorphism (P ≤ 5 kbar, T ≤ 750°C) of the upper crustal levels. (ii) The lower crustal granulites are uplifted, and suffered local partial melting and then retrogression into the amphibolite facies at 550 ± 50°C – 5 kbar. Granulites are extruded in the core of a crustal-scale anticlinal fold, granulites being retrogressed only on the rims of the anticline. Crustal-scale folding, along with other structural features results from intense NE-SW shortening, that prevailed during the Late Archean orogenic cycle. Strike-slip and extensive motions are only minor in that process. (iii), Top-to-the-East thrusting and nappe piling has (at least locally) occurred under lower amphibolite to greenschist facies conditions. Finally, it seems that (iv) the Paleoproterozoic 1.7 Ga structural imprint may have only affected the rims of the Archean units. The tectonic context observed in the 1.7 Ga Cape Hunter phyllites features mainly E-W shortening component and vertical extrusion. The Eastern (Mertz) and Western (Port Martin) parts of the Archean block were reactivated by localized dextral shearing.