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

• 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), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet Saint-Étienne (UJM)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-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)-Centre National de la Recherche Scientifique (CNRS)-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 (. - 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, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE 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: Antarctica; Archean; Paleoproterozoic; Granulites; extrusion; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; [SDE.MCG.CG]Environmental Sciences/Global Changes/domain_sde.mcg.cg; East Antarctica; Terre Adélie; Terre-Adélie; Commonwealth Bay; Port Martin; Port-Martin; Cape Hunter; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-00103170; https://hal.archives-ouvertes.fr/hal-00103170/document; https://hal.archives-ouvertes.fr/hal-00103170/file/Menot_et_al._2005.pdf; https://doi.org/10.1016/S1342-937X(05)70258-6

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.