IPEV Home

French Polar Institute Literature Database

Home |  Show All |  Simple Search |  Advanced Search
Quick Search:
151–160 of 244 records found matching your query (RSS | history):
Select All    Deselect All [1–10] << 11 12 13 14 15 16 17 18 19 20 >> [21–25]
List View
 | 
Citations
 | 
Details
   print
  Records Links
Author Albertin, S., Savarino, J., Bekki, S., T. Roberts, T., Barret, B., Mao, J., Simpson, W., Law, K. openurl 
  Title Isotopic constraints on the sources and fate of atmospheric nitrate in Fairbanks, Alaska: preliminary results of the pre-ALPACA campaign Type Communication
  Year 2021 Publication Paces meeting, may 2021 Abbreviated Journal  
  Volume Issue Pages  
  Keywords  
  Abstract  
  Programme (up) 1215  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8513  
Permanent link to this record
 
 
Author Alexis Burr openurl 
  Title Etude de la fermeture des pores lors de la densification du névé polaire // Investigation of pore closure during polar firn densification Type Thesis
  Year 2021 Publication Université de bretagne occidentale Abbreviated Journal  
  Volume Thesis started in October 2021 Issue Pages  
  Keywords 540 Anisotropie Anisotropy Densification Discrete simulations Fermeture des pores Firn Névé Névés Pore closure Simulations discrètes Tomographie X Viscoplasticité X-Ray tomography  
  Abstract .La densification du névé en glace est un processus essentiel à comprendre pour interpréter les enregistrements climatiques. Une bonne connaissance des mécanismes permet une datation précise de l'air capturé dans la glace lors de la fermeture des pores. Celle-ci est plus vieille que l'air capturé à cause du transport des gaz dans la colonne de névé plus rapide que la densification de celui-ci. Cette différence d'âge entre la glace et le gaz est généralement appelé le Δage. La densification de la neige consiste en un processus complexe de réarrangement de grains, de frittage et de déformation viscoplastique. Bien que le comportement viscoplastique du cristal de glace soit fortement anisotrope, les modèles de densification actuels ne tiennent pas compte de cette anisotropie. De plus, le caractère granulaire du névé affecte aussi sa densification. La relation entre la fermeture des pores et les mécanismes microstructuraux sous-jacents est encore méconnue. Le but de cette thèse est d'incorporer l'aspect granulaire ainsi que l'anisotropie du cristal de glace dans une approche de modélisation innovante de la densification. Des expériences sur l'indentation viscoplastique de cylindres monocristallins de glace ont été réalisées pour proposer une loi de contact basée sur la théorie de l'indentation, et prenant en compte la déformation préférentielle du cristal de glace sur les plans basaux. Cette loi de contact a été implémentée dans un code utilisant la méthode des éléments discrets pour prédire la densification du névé.La micro-tomographie aux rayons X a été utilisée pour caractériser ex situ le névé polaire en trois dimensions à différentes étapes de la densification (ρ= 0.55-0.88 g/cm3), i.e. pour différentes profondeurs (~23 à 130m). Une étude fine de la fermeture des pores et de différentes caractéristiques morphologiques et physiques a été réalisée pour les sites polaires Dome C et Lock In. Des essais mécaniques ont aussi été réalisés in situ sur du névé extrait de Dome C dans le but de modéliser la densification du névé. Les observations microstructurales des expériences ex situ et in situ révèlent d'importantes différences dues aux vitesses relativement importantes utilisées lors des essais mécaniques. Ces vitesses rapides permettent de découpler la contribution des cinétiques de diffusion de la contribution viscoplastique de la déformation. Les effets de ces contributions sur la morphologie des pores et leurs fermetures sont discutés. Pour caractériser la fermeture des pores, cette thèse propose un indice de connectivité définit par le ratio entre le volume du plus gros pore sur la porosité totale. En effet, cet indice est plus approprié lors de l'utilisation de la tomographie aux rayons X que le ratio de pores fermés pour prédire la densité au close-off.  
  Programme (up) 1216  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8347  
Permanent link to this record
 
 
Author Grégoire Mureau openurl 
  Title Étude des impacts des événements extrêmes sur le massif dunaire de la plage de Sanvík (Islande) Type Master 1
  Year 2021 Publication Université de bretagne occidentale Abbreviated Journal  
  Volume https://www-iuem.univ-brest.fr/pops/attachments/26 Issue Pages 62 p.  
  Keywords  
  Abstract  
  Programme (up) 1216  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8383  
Permanent link to this record
 
 
Author Gómez Coutouly, Yan Axel openurl 
  Title Un peuplement antérieur à 20 000 ans en Amérique ? Le caractère anthropique des sites de Pedra Furada (Brésil) en question Type Journal
  Year 2021 Publication Bulletin de la société préhistorique française Abbreviated Journal  
  Volume 118 Issue 2 Pages 245-275  
  Keywords  
  Abstract  
  Programme (up) 1217  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8690  
Permanent link to this record
 
 
Author Yan Axel Gomez Coutouly file  openurl
  Title Un peuplement antérieur à 20 000 ans en Amérique ? Type Book Chapter
  Year 2021 Publication « Et pourtant elle tourne ! » blocages épistémologiques en archéologie. Colloque organisé par Laure Fontana et Sophie A. de Beaune, (Projets collectifs ArScAn), 18-19 novembre 2021, Campus de Nanterre Université, France Abbreviated Journal  
  Volume Issue Pages  
  Keywords  
  Abstract  
  Programme (up) 1217  
  Campaign  
  Address  
  Corporate Author Thesis Bachelor's thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8692  
Permanent link to this record
 
 
Author Ryo Okuwaki, Stephen P. Hicks, Timothy J. Craig, Wenyuan Fan, Saskia Goes, Tim J. Wright, Yuji Yagi doi  openurl
  Title Illuminating a Contorted Slab With a Complex Intraslab Rupture Evolution During the 2021 Mw 7.3 East Cape, New Zealand Earthquake Type Journal
  Year 2021 Publication Geophysical Research Letters Abbreviated Journal  
  Volume 48 Issue 24 Pages e2021GL095117  
  Keywords earthquake rupture finite-fault inversion Hikurangi intraslab earthquakes slab geometry source imaging  
  Abstract The state-of-stress within subducting oceanic plates controls rupture processes of deep intraslab earthquakes. However, little is known about how the large-scale plate geometry and the stress regime relate to the physical nature of the deep intraslab earthquakes. Here we find, by using globally and locally observed seismic records, that the moment magnitude 7.3 2021 East Cape, New Zealand earthquake was driven by a combination of shallow trench-normal extension and unexpectedly, deep trench-parallel compression. We find multiple rupture episodes comprising a mixture of reverse, strike-slip, and normal faulting. Reverse faulting due to the trench-parallel compression is unexpected given the apparent subduction direction, so we require a differential buoyancy-driven stress rotation, which contorts the slab near the edge of the Hikurangi plateau. Our finding highlights that buoyant features in subducting plates may cause diverse rupture behavior of intraslab earthquakes due to the resulting heterogeneous stress state within slabs.  
  Programme (up) 133  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1944-8007 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 8313  
Permanent link to this record
 
 
Author Afsaneh Mohammadzaheri, Karin Sigloch, Kasra Hosseini, Mitchell G. Mihalynuk doi  openurl
  Title Subducted Lithosphere Under South America From Multifrequency P Wave Tomography Type Journal
  Year 2021 Publication Journal of Geophysical Research: Solid Earth Abbreviated Journal  
  Volume 126 Issue 6 Pages e2020JB020704  
  Keywords Andes intra-arc intra-oceanic subduction seismic tomography South America structure of the mantel  
  Abstract We analyze mantle structure under South America in the DETOX-P1 seismic tomography model, a global-scale, multifrequency inversion of teleseismic P waves. DETOX-P1 inverts the most extensive data set of broadband, waveform-based traveltime measurements to date, complemented by analyst-picked traveltimes from the ISC-EHB catalog. The mantle under South America is sampled by ∼665,000 cross-correlation traveltimes measured on 529 South American broadband stations and on 5,389 stations elsewhere. By their locations, depths, and geometries, we distinguish four high-velocity provinces under South America, interpreted as subducted lithosphere (“slabs”). The deepest (∼1,800–1,200 km depth) and shallowest (<600 km) slab provinces are observed beneath the Andean Cordillera near the continent’s northwest coast. At intermediate depths (1,200–900 km, 900–600 km), two slab provinces are observed farther east, under Brazil, Bolivia and Venezuela, with links to the Caribbean. We interpret the slabs relative to South America’s paleo-position over time, exploring the hypothesis that slabs sank essentially vertically after widening by viscous deformation in the mantle transition zone. The shallowest slab province carries the geometric imprint of the continental margin and represents ocean-beneath-continent subduction during Cenozoic times. The deepest, farthest west slab complex formed under intra-oceanic trenches during late Jurassic and Cretaceous times, far west of South America’s paleo-position adjoined to Africa. The two intermediate slab complexes record the Cretaceous transition from westward intra-oceanic subduction to eastward subduction beneath South America. This geophysical inference matches geologic records of the transition from Jura-Cretaceous, extensional “intra-arc” basins to basin inversion and onset of the modern Andean arc ∼85 Ma.  
  Programme (up) 133  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-9356 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7991  
Permanent link to this record
 
 
Author L A Ermert, K Sager, T Nissen-Meyer, A Fichtner doi  openurl
  Title Multifrequency inversion of global ambient seismic sources Type Journal
  Year 2021 Publication Geophysical Journal International Abbreviated Journal  
  Volume 225 Issue 3 Pages 1616-1623  
  Keywords  
  Abstract We develop and apply a method to constrain the space- and frequency-dependent location of ambient noise sources. This is based on ambient noise cross-correlation inversion using numerical wavefield simulations, which honour 3-D crustal and mantle structure, ocean loading and finite-frequency effects. In the frequency range from 3 to 20 mHz, our results constrain the global source distribution of the Earth’s hum, averaged over the Southern Hemisphere winter season of 9 yr. During Southern Hemisphere winter, the dominant sources are largely confined to the Southern Hemisphere, the most prominent exception being the Izu-Bonin-Mariana arc, which is the most active source region between 12 and 20 mHz. Generally, strong hum sources seem to be associated with either coastlines or bathymetric highs. In contrast, deep ocean basins are devoid of hum sources. While being based on the relatively small number of STS-1 broad-band stations that have been recording continuously from 2004 to 2013, our results demonstrate the practical feasibility of a frequency-dependent noise source inversion that accounts for the complexities of 3-D wave propagation. It may thereby improve full-waveform ambient noise inversions and our understanding of the physics of noise generation.  
  Programme (up) 133  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0956-540X ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7992  
Permanent link to this record
 
 
Author Jun Xie, Risheng Chu, Sidao Ni doi  openurl
  Title Evaluating Global Tomography Models With Antipodal Ambient Noise Cross-Correlation Functions Type Journal
  Year 2021 Publication Journal of Geophysical Research: Solid Earth Abbreviated Journal  
  Volume 126 Issue 3 Pages e2020JB020444  
  Keywords ambient noise cross-correlation functions antipodal surface waves mantle heterogeneity tomography model evaluation  
  Abstract It is essential to evaluate global tomography models, which provide important information for understanding Earth's structure and dynamics. Long-period surface waves propagating between antipodal stations are good candidates for this purpose since they depend on global-scale velocity variations in the upper mantle. In this study, we extract minor-arc and major-arc Rayleigh waves from ambient noise cross correlations between GEOSCOPE station AIS and ∼1,800 USArray stations near the antipode of AIS. We identify two Rayleigh-wave-focusing regions and simulate the observed maximum amplitude pattern at the antipodal region using synthetic surface waves based on three global tomography models. Our simulations suggest that seismic heterogeneity of the tomography models need to be inflated by a factor of 2–3 in oceanic regions to explain the observed focusing pattern of surface waves near the antipodal region.  
  Programme (up) 133  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2169-9356 ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7993  
Permanent link to this record
 
 
Author A. Baranov, R. Tenzer, A. Morelli doi  openurl
  Title Updated Antarctic crustal model Type Journal
  Year 2021 Publication Gondwana Research Abbreviated Journal  
  Volume 89 Issue Pages 1-18  
  Keywords Antarctica Crustal structure Gondwana Sediments  
  Abstract We use seismic data together with a subglacial bedrock relief from the BEDMAP2 database to obtain a new three-layer model of the consolidated (crystalline) crust of Antarctica that locally improves the global seismic crustal model CRUST1.0. We collect suitable data for constructing crustal layers, analyse them and build maps of the crustal layer thickness and seismic velocities. We use the subglacial relief according to a tectonic configuration and then interpolate data using a statistical kriging method. The P-wave velocity information from old seismic profiles have been supplemented with the new shear-wave velocity models. We adjust the thickness of crustal layers by multiplying a total crustal thickness by a percentage ratio of each individual layer at each point. Our results reveal large variations in seismic velocities between different crustal blocks forming Antarctica. The most pronounced differences exist between East and West Antarctica. In East Antarctica, a high P-wave velocity (vP > 7 km/s) layer in the lower crust is absent. The P-wave velocity in the lower crust changes from 6.1 km/s beneath the Lambert Rift to 6.9 km/s beneath the Wilkes Basin. In West Antarctica, a thick mafic lower crust is characterized by large P-wave velocities, ranging from 7.0 km/s under the Ross Sea to 7.3 km/s under the Byrd Basin. In contrast, velocities in the lower crust beneath the Transantarctic and Ellsworth-Whitmore Mountains are ~6.8 km/s. The P-wave velocities in the upper crust in East Antarctica are within the range 5.5–6.4 km/s. The upper crust of West Antarctica is characterized by the P-wave velocities of 5.6–6.3 km/s. The P-wave velocities in the middle crust vary within 5.9–6.6 km/s in East Antarctica and within 6.3–6.5 km/s in West Antarctica. A low-velocity layer (5.8–5.9 km/s) is detected at depth of ~20–25 km beneath the Princes Elizabeth Land.  
  Programme (up) 133  
  Campaign  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1342-937X ISBN Medium  
  Area Expedition Conference  
  Notes Approved yes  
  Call Number Serial 7994  
Permanent link to this record
Select All    Deselect All [1–10] << 11 12 13 14 15 16 17 18 19 20 >> [21–25]
List View
 | 
Citations
 | 
Details
   print
toggle visibility Cite Options
Home Show Record  |  Help