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| Lamarque, Gaelle; Bascou, Jerome; Menot, Rene-pierre; Paquette, Jean-louis; Couzinie, Simon; Rolland, Yann; Cottin, Jean-yves. |
| This study presents the first geochronological results on basement rocks from the Penguin-Bage-Webb (PBW) domain located east of the Neoarchean-Paleoproterozoic Terre Adélie craton, Antarctica. Investigated samples are paragneiss xenoliths hosted within early Paleozoic granitoids, which were emplaced during the Ross orogeny. Zircon UPb dating yielded ages ranging from the Archean to the Cambrian, with a dominant Ediacaran (550–635 Ma) population and maximum depositional ages around 570–575 Ma. U–Th–Pb analyses of monazite suggest that the metamorphic event that formed the gneiss samples occured at ca. 515 Ma, shortly prior to incorporation within the granitic magmas. The studied samples likely represent relics of the pre-Gondawana Pacific margin, which was... |
| Tipo: Text |
Palavras-chave: Gondwana margin; Ross orogeny; George V Land; Antarctica-Australia connection; Zircon and monazite U-Pb dating. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00457/56903/58865.pdf |
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| Basile, Christophe; Girault, Igor; Paquette, Jean-louis; Agranier, Arnaud; Loncke, Lies; Heuret, Arnauld; Poetisi, Ewald. |
| We report the discovery of 173.4 Ma hotspot-related magmatic rocks in the basement of the Demerara Plateau, offshore French Guiana and Suriname. According to plate reconstructions, a single hotspot may be responsible for the magmatic formation of (1) both the Demerara Plateau (between 180 and 170 Ma) and the Guinea Plateau (circa 165 Ma) during the end of the Jurassic rifting of the Central Atlantic; (2) both Sierra Leone and Ceara Rises (mainly from 76 to 68 Ma) during the upper Cretaceous oceanic spreading of the Equatorial Atlantic ocean; (3) the Bathymetrists seamount chain since the upper Cretaceous. The present-day location of the inferred Sierra Leone hotspot should be 100 km west of the Knipovich Seamount. |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00628/74034/73363.pdf |
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| Le Gall, Bernard; Authemayou, Christine; Ehrhold, Axel; Paquette, Jean-louis; Bussien, Denise; Chazot, Gilles; Aouizerat, Arthur; Pastol, Yves. |
| An exceptional structural picture of the immerged Variscan basement, offshore the Leon metamorphic domain, is supplied by high-resolution LiDAR and echosounder data recorded in the Molene archipelago, western Brittany (France). Various types of fabrics are identified and, from in situ rock sample analyses further combined with field structural data, are interpreted on a lineament trajectory map as the trace of magmatic and tectonic structures. Our onshore/offshore study leads us to propose a two-phase kinematic model that emphasizes the role of a strike-slip duplex in an EW-trending relay zone linking the North Armorican and Pierres Noires ductile shear zones (NASZ, PNSZ). Dextral shearing occurred within a transtensional setting, synchronously with... |
| Tipo: Text |
Palavras-chave: Armorican massif; Leon metamorphic domain; Offshore structural mapping; LiDAR records; Dextral ductile shearing; U/Pb zircon/monazite dating. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00194/30490/28895.pdf |
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