Consulta: creatorFacets:"Paquette, Jean-louis"
Registros recuperados: 4
Data/hora: 26/07/2024 22:45:36

Bimodal zircon ages from Natash volcanics (southeast Egypt) and the link between eruption mechanisms and Late Cretaceous tectonics
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Abu El-rus, Mohamed Ali; Paquette, Jean-louis; Chazot, Gilles; Vannucci, Riccardo.
Trachyte plugs from the Natash volcanic field have been precisely dated using in situ U-Pb geochronology on zircon grains at similar to 93Ma. Available zircon ages thus suggest that the overall volcanic history at Natash was probably shorter than previously estimated based on Rb-Sr and K-Ar ages, which are more sensitive to element mobility. Basaltic flows and trachyte plugs were produced by a largely synchronous, Upper Cretaceous volcanic activity that occurred in the Natash area at the onset of the extensional fracturing that preceded and accompanied the doming of the Afro-Arabian Shield. Extraction and eruption of volumetrically dominant basalts from deeper lithospheric levels were ruled by major NW-SE strike-slip faults, whereas both major and...
Tipo: Text
Palavras-chave: Eastern Desert Egypt; Cretaceous volcanism; Natash volcanics; Trachyte plugs; U-Pb zircon ages.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00637/74936/75943.pdf

Ediacaran to lower Cambrian basement in eastern George V Land (Antarctica): Evidence from U Pb dating of gneiss xenoliths and implications for the South Australia- East Antarctica connection
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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

LiDAR offshore structural mapping and U/Pb zircon/monazite dating of Variscan strain in the Leon metamorphic domain, NW Brittany
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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

The Jurassic magmatism of the Demerara Plateau (offshore French Guiana) as a remnant of the Sierra Leone hotspot during the Atlantic rifting
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: 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
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00628/74034/73363.pdf