Yann Rolland, Matthias Bernet, Peter van der Beek, Cécile Gautheron, Guillaume Duclaux, Jérôme Bascou, Mélanie Balvay, Laura Héraudet, Christian Sue, René-Pierre Ménot. (2019). Late Paleozoic Ice Age glaciers shaped East Antarctica landscape (Vol. 506).
Abstract: The erosion history of Antarctica is fundamental to our understanding of interlinks between climate and glacier dynamics. However, because of the vast polar ice sheet covering more than 99% of Antarctica land mass, the continental surface response to glacial erosion remains largely unknown. Over the last decade the subglacial topography of Antarctica has been imaged by airborne radar surveys. These studies revealed high and complex sub-glacial relief in the core of the East Antarctic shield, interpreted as resulting from rifting episodes and low long-term erosion rates, or repeated large-scale glacial retreats and advances. In East Antarctica, thermochronology studies have revealed a spatially localized Cenozoic erosion starting after 34 Ma, with a maximum denudation of 2 km in the Lambert Trough. Low pre-glacial erosion rates before 34 Ma have been inferred since the Permian period, following a phase of significant (>2 km) erosion during the Late Paleozoic between 350 and 250 Ma. However, the exact extent, magnitude and significance of this Late-Paleozoic erosion phase remain elusive. Here we show that homogeneous exhumation occurred at the scale of the Terre Adélie margin of East Antarctica in response to major glacial erosion during the Late Paleozoic Ice Age (LPIA). Our data require homogeneous exhumation and >4 km erosion between 340 and 300 Ma, along a 600-km profile along the Terre Adélie–George V Land coast. The data are inconsistent with either exhumation during Permian rifting, or with significant (>1.5 km) Cenozoic glacial erosion, which requires LPIA glaciers to have been temperate, promoting glacial sliding, erosion and sediment transfer, even at high latitudes, unlike in the present situation.
Keywords: Antarctica erosion exhumation glaciation LPIA thermochronology
Programme: 1003
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Gaëlle Lamarque, Jérôme Bascou, René-Pierre Ménot, Jean-Louis Paquette, Simon Couzinié, Yann Rolland, Jean-Yves Cottin. (2018). 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 (Vol. 318-319). Bachelor's thesis, , .
Abstract: 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 subsequently deformed and metamorphosed during the early Paleozoic Ross orogeny. The obtained zircon UPb date distributions present similarities with those of the Kanmantoo and Nargoon sediments in Southern Australia and provide new constrains for the correlations between East Antarctica and South Australia before the opening of the Southern Ocean.
Keywords: Antarctica-Australia connection George V Land; Gondwana margin; Ross orogeny; Zircon and monazite UPb dating
Programme: 1003
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Encelyn Voisine, Yann Rolland, Matthias Bernet, Julien Carcaillet, Guillaume Duclaux, Jérôme Bascou, Christian Sue, Mélanie Balvay, René-Pierre Ménot. (2020). Antarctic erosion history reconstructed by Terre Adélie moraine geochronology.
Abstract: We report apatite fission-track and 10Be terrestrial cosmogenic nuclide (TCN) dating of 14 moraine boulders originating from inland Terre Adélie, East Antarctica. These data show cooling of the Proterozoic Terre Adélie craton at < ~120°C between 350 and 300 Ma, suggesting > 4 km temperate glacial erosion during the Late Palaeozoic Ice Age, followed by nearly null Mesozoic erosion and low glacial erosion (< 2 km) in the Cenozoic. Based on glacial flux maps, the origin of the boulders may be located ~400 km upstream. Preliminary TCN (10Be) datings of moraine boulders cluster within the last 30 ka. Cosmogenic ages from the Lacroix Nunatak suggest a main deglaciation after the Younger Dryas at c. 10 ka, while those of Cap Prud'homme mostly cluster at 0.6 ka, in agreement with an exhumation of boulders during the Little Ice Age.
Keywords: cosmogenic nuclide dating deglaciation exhumation fission-track dating Late Palaeozoic Ice Age subglacial incision
Programme: 1003
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Lamarque G. (2015). Structures et déformations associées au fonctionnement d'une zone de cisaillement majeure : étude multi-échelle de la bordure Est du craton Néoarchéen-Paléoprotérozoïque de Terre Adélie (Mertz shear zone, Antarctique de l'Est) (Vol. Soutenue le 26-11-2015). Ph.D. thesis, , .
Abstract: L'étude du fonctionnement et de la structure des grandes zones de cisaillement, ainsi que de leur évolution dans l'espace et dans le temps est primordiale car elles accommodent la majeure partie de la déformation dans la croûte intermédiaire, la croûte inférieure et également dans le manteau supérieur. La zone de cisaillement du Mertz (MSZ ; longitude 145°Est, Antarctique) s’est révélée être un objet clé pour étudier la localisation de la déformation. La MSZ se situe sur la bordure Est du craton néoarchéen-paléoprotérozoïque de Terre Adélie (TAC) et le sépare d'un domaine granitique Paléozoïque à l'Est. Les études précédentes suggèrent que cette structure décrochante représente la continuité de la zone de cisaillement de Kalinjala (KSZ, Sud de l'Australie) avant l'ouverture de l'océan Austral. Les roches à l'affleurement indiquent que cette structure a été formée dans la croûte intermédiaire en contexte transpressif dextre à 1.7 Ga. La structure de la MSZ a été étudiée depuis l'échelle du terrain jusqu'à l'échelle du micromètre. L'analyse des structures de terrain indique que la déformation paléoprotérozoïque est principalement accommodée par des zones de cisaillement localisées qui sont extrêmement anastomosées au niveau de la MSZ et qui deviennent plus éparses au sein du TAC. Les microstructures et les orientations préférentielles de réseau (OPR) des minéraux (quartz, feldspaths, biotite, amphibole et orthopyroxène) de la MSZ montrent des caractéristiques communes interprétables en terme de conditions, de cinématique et de régime de la déformation qui se distinguent de celles observées dans les boudins tectonique du TAC. Ces derniers montrent, quant à eux, des microstructures et OPR qui révèlent une variété de mécanismes de déformation développés lors de leur formation à 2.5 Ga.L'étude sismologique (fonctions récepteurs et anisotropie des ondes SKS) permet d'apporter de nouvelles données pour la cartographie des structures profondes de la MSZ, du TAC et du domine paléozoïque. Les résultats des fonctions récepteurs indiquent que la croûte est épaisse d'environ 40 à 44 km sous le TAC, 36 km à l'aplomb de la MSZ et 28 km dans le domaine paléozoïque à l'Est. L'analyse de l'anisotropie des ondes SKS suggère que la structuration du manteau sous le craton (ϕ≈N90°E, δt=0,8-1,6s) est différente de celle sous le domaine paléozoïque (ϕ≈N60°E, δt=0,6s). Ainsi, la MSZ constitue la frontière entre ces deux lithosphères ayant des épaisseurs crustales et une structuration du manteau différentes. Enfin, l'étude géochronologique (U-Pb sur zircons et monazites) révèle que le socle du domaine à l'Est de la MSZ présente des âges et une histoire géodynamique différents du TAC. Les âges hérités archéens et paléoprotérozoïques sont similaires à ceux des terrains situés à l'Est de la KSZ au Sud de l'Australie, confirmant ainsi la connexion entre les zones de cisaillement du Mertz et de Kalinjala. De plus, les âges paléozoïques des zircons hérités et métamorphiques et la position géographique des affleurements à l'ouest de la chaîne Transantarctique suggèrent que les échantillons étudiés sont issus d'une marge passive anté-Gondwana formée au sein d'un bassin arrière arc ouvert dans la croûte continentale juste avant la collision de Ross à ≈514-505 Ma.Ainsi, cette étude permet de préciser l'évolution géodynamique à l'Est de la MSZ, et d'apporter de nouveaux éléments pour la connexion avec les terrains du Sud de l'Australie. Par ailleurs, cette thèse souligne l'importance de l'héritage tectonique dans le développement des zones de cisaillement avec, dans le cas de la MSZ, la présence de structures héritées archéennes, ainsi que des processus de localisation de la déformation au sein des lithosphères cratoniques au moins depuis le Paléoprotérozoïque
Programme: 1003
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Sue, C., Bascou. (2016). Analyse quantitative de la déformation cassante en terre Adélie : résultats préliminaires.
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Bascou, J., Henry, B., Ménot, R.p., Funaki, M., Mourier, T. (2017). Apport de l’ASM dans l’étude des terrains de la Terre Adélie (Est Antarctique).
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Gaëlle Lamarque, Guilhem Barruol, Fabrice R. Fontaine, Jérôme Bascou, René-Pierre Ménot. (2015). Crustal and mantle structure beneath the Terre Adélie Craton, East Antarctica: insights from receiver function and seismic anisotropy measurements (Vol. 200).
Abstract: The Terre Adélie and George V Land (East Antarctica) represent key areas for understanding tectonic relationships between terranes forming the Neoarchean-Palaeoproterozoic Terre Adélie Craton (TAC) and the neighbouring lithospheric blocks, together with the nature of its boundary. This region that represents the eastern border of the TAC is limited on its eastern side by the Mertz shear zone (MSZ) separating more recent Palaeozoic units from the craton. The MSZ, that recorded dextral strike-slip movement at 1.7 and 1.5 Ga, is likely correlated with the Kalinjala or Coorong shear zone in South Australia, east of the Gawler Craton and may therefore represent a frozen lithospheric-scale structure. In order to investigate the lithospheric structure of the TAC and the MSZ, we deployed from 2009 October to 2011 October four temporary seismic stations, which sampled the various lithospheric units of the TAC and of the neighbouring Palaeozoic block, together with the MSZ. We used receiver function method to deduce Moho depths and seismic anisotropy technique to infer the upper mantle deformation. Results from receiver functions analysis reveal Moho at 40–44 km depth beneath the TAC, at 36 km under the MSZ and at 28 km beneath the eastern Palaeozoic domain. The MSZ therefore delimits two crustal blocks of different thicknesses with a vertical offset of the Moho of 12 km. Seismic anisotropy deduced from SKS splitting at stations on the TAC shows fast polarisation directions (Φ) trending E–W, that is, parallel to the continental margin, and delay times (δt) ranging from 0.8 to 1.6 s. These results are similar to the splitting parameters observed at the permanent GEOSCOPE Dumont D'Urville station (DRV: Φ 95°N, δt 1.1 s) located in the Palaeoproterozoic domain of TAC. On the MSZ, the small number of good quality measurements limits the investigation of the deep signature of the shear zone. However, the station in the Palaeozoic domain shows Φ trending N60°E, which is significantly different to the Φ trending measurements from stations on the TAC, suggesting that the MSZ may also represent a major frontier between the Neoarchean-Palaeoproterozoic and Palaeozoic terranes.
Programme: 1003
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Ménot, R.P. (2021). The Geology of East Antarctica (between ∼85° E and ∼145° E), in Geology of the Antarctic Continent.
Abstract: This chapter treats the Antarctic region facing West and South Australia, approximately from 85° E to 145° E (Fig. 1-1), i.e. the easternmost province of the “East Antarctic Shield” (see chapters 1.2/1.2.1). Therefore, the following major areas will be described: from West to East, Kaiser-Wilhelm-II.-Land, Queen Mary Land, Wilkes Land, Terre Adélie and western George V Land. Eastern George V Land and northern Victoria Land are excluded from this review as they can be regarded as the foreland of the Transantarctic Mountains geological domain (chapters 4 and 5).
Programme: 1003
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Charly Massa, Bianca B. Perren, Émilie Gauthier, Vincent Bichet, Christophe Petit, Hervé Richard. (2012). A multiproxy evaluation of Holocene environmental change from Lake Igaliku, South Greenland (Vol. 48).
Abstract: This is the first integrated multiproxy study to investigate climate, catchment evolution and lake ecology in South Greenland. A 4-m-long sedimentary sequence from Lake Igaliku (61º 00′ N, 45º 26′ W, 15 m asl) documents major environmental and climatic changes in south Greenland during the last 10 ka. The chronology is based on a 210Pb and 137Cs profile and 28 radiocarbon dates. The paleoenvironmental history is interpreted on the basis of magnetic susceptibility, grain size, total organic carbon, total nitrogen and sulphur, sedimentation rates, pollen, and diatom assemblages. The basal radiocarbon date at ca. 10 cal ka BP provides a minimum age for the deglaciation of the basin, which is followed by ~500 years of high sedimentation rates in a glacio-marine environment. After the glacio-isostatic emergence of the basin ca. 9.5 cal ka BP, limnological and terrestrial proxies suggests early warmth, which may have been interrupted by a cold, dry and windy period between 8.6 and 8.1 cal ka BP. A dry and windy event ~5.3–4.8 cal ka BP preceded the Neoglacial transition at Lake Igaliku, which is characterized by a shift toward moister and perhaps cooler conditions ~4.8 cal ka BP, causing major changes in terrestrial and aquatic ecological conditions. Significant cooling is documented after ~3 cal ka BP. Since ~1 cal ka BP the climatic-driven changes were overprinted by the human influence of Norse and recent agriculture.
Programme: 1004
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Roy Jean-Claude. (2009). La Saga des Vieux Grès Rouges du Spitzberg (archipel du Svalbard, Arctique) – Une histoire géologique et naturelle. Postface de Jean Dercourt, secrétaire perpétuel de l'Académie des Sciences. (Vol. Tome 1). Bachelor's thesis, , .
Abstract: d'après le mémoire de thèse de doctorat de J.-C. Roy, UPMC 28 septembre 2007, complété et augmenté.
Programme: 1005
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