Paleoproterozoic tectonics around 1.69 Ga in Adélie Land (East Antarctica)

• Published in: Precambrian Research
• Main Authors: Gapais, Denis, Pelletier, Anne, Ménot, René-Pierre, Peucat, Jean-Jacques
• Other Authors: Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre Armoricain de Recherches en Environnement-Centre National de la Recherche Scientifique (CNRS), 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Tectonics; Structural analysis; Paleoproterozoic; Antarctica; Terre Adélie; [SDU.STU.TE]Sciences of the Universe [physics]/Earth Sciences/Tectonics; East Antarctica; Terre-Adélie; Antarc*; antartic*
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-00279839; https://doi.org/10.1016/j.precamres.2007.10.011

International audience This paper describes the deformation that occurred in the Paleoproterozoic terrains of the Terre Adélie Craton (East Antartica) at ca. 1.69 Ga. The structural pattern is marked by sub-vertical deformation zones, trending N340­360°, that rework sub-horizontal fabrics. Both types of structures developed under similar partial melting conditions (thermal and pressure peaks around 700­750 °C and 500­600 MPa, respectively) and are in part coeval. Vertical zones show kinematic indicators of dextral transpression. Strike-slip components appear to increase in intensity from W to E, toward the contact between Paleoproterozoic terrains and Archaean blocks located to the East. Flat-lying foliations bear stretching lineations, which strike N340­360°, at low-angle to the transpressional shear zones and to the boundaries between major units. Structural and metamorphic signatures are consistent with a model in which hot and weak continental domains converge toward a stiffer craton. Horizontal shortening was accommodated along vertical transpressional zones. Thickening combined with significant magmatic input might have triggered gravity-driven horizontal crustal flow at high angle to the convergence direction.