Search results for "glaciology"
showing 10 items of 26 documents
Improvement of snow physical parameters retrieval using SAR data in the Arctic (Svalbard)
2018
International audience; Arctic snow cover dynamics offer a changing face in terms of temporal duration andwater equivalent, due to recent climate change conditions (Callaghan et al., 2011; Lemke & Jacobi,2012). Indeed, the Arctic is now experiencing some of the most rapid and severe climate change onearth. In this context, innovative and improved methods are helpful to enhance management of thesnow-pack resource for climate research, hydrology and human activities. The characteristics of Arcticsnow are different from “temperate” snow (i.e. the Alps), in terms of thickness, internal structure, thermalconductivity, and metamorphism. Ground observation often indicates wind slab at the snow sur…
Porewater pressure control on subglacial soft sediment remobilization and tunnel valley formation: A case study from the Alnif tunnel valley (Morocco)
2014
25 pages; International audience; In the eastern part of the Moroccan Anti-Atlas Mountains, the Alnif area exposes a buried Ordovician glacial tunnel valley (5 km wide, 180 m deep) cut into preglacial marine sediments. The preglacial sedimentary sequence, deposited in a marine environment, is characterized by a typical "layer-cake" configuration of permeable (sand) and impermeable (clays and early-cemented sandstones) layers. At the base of the tunnel valley, a discontinuous and fan-shaped glacial conglomeratic unit 10 to 15 m thick occurs, erosively deposited over preglacial marine sediments. The conglomeratic unit is composed of preglacial intraclasts embedded within a sandy matrix. Both …
STRUCTURATION EXTENSIVE ET TRANSTENSIVE AU DEVONO-DINANTIEN DU BASSIN DE TIM MERSOÏ (BORDURE OCCIDENTALE DE L'AÏR, NORD NIGER).
2007
International audience; L'étude tectono-sédimentaire préliminaire du bassin de Tim Mersoï confirme le contrôle exercé par les accidents majeurs N-S d'In Azaoua-Arlit, N30°E de Madaouéla et N70°E de Tin Adrar sur la géométrie du remplissage sédimentaire. Pour la période dévono-dinantienne, deux phases majeures de structuration ont été mises en évidence : une phase extensive, multi-épisode (du Dévonien au Viséen supérieur) et une phase transtensive débutant au Viséen terminal. Ces deux phases tectoniques majeures sont responsables de l'ouverture polyphasée du bassin. Pendant la phase extensive, la direction d'allongement qui était globalement N90°E au Dévonien, devient successivement N70°E pu…
Does porewater or meltwater control tunnel valley genesis? Case studies from the Hirnantian of Morocco.
2015
18 pages; International audience; Several Ordovician tunnel valleys are exposed in the Moroccan Anti-Atlas Mountains, including the Alnif and the Foum Larjamme tunnel valleys, located 150 km away from each other. Sedimentological and deformational analyses of these two glacial troughs reveal that differing processes lead to their formations.The Alnif tunnel valley contains numerous deformation structures within sediments both below and above the main glacial erosion contact surface. Ball-structures and clastic dykes occur within preglacial sediments down to 35 m below glacial incisions while overlying glacial sediments contain fluted surfaces, clastic dykes, dewatering structures, folds and…
Étude du paléoclimat ordovicien (440 millions d'années) à travers l'enregistrement de la dynamique des glaciers au Niger.
2008
6 pages; National audience
At the bedside of a small Spitsberg glacier
2019
Quantification of sediment transport into Kongsfjorden due to the glacier melt dynamics of Austre Lovenbreen using terrestrial laser scanning
2018
International audience; Climate warming causes a decrease of glaciers in Svalbard. This results in sig-nificant changes of the geomorphology of areas in glacier catchments where iceand permafrost is melting. In particular the snout of the glacier melts drasticallyand the water outflow of the glacier changes sometimes its direction. Sedimentand bed load transport forms new river beds in the moraine, and the sedimentsinvolved are transported downstream into the fjords. In recent years terrestriallaser scanning technology has developed significantly, so it is possible to mea-sure the surface of a whole glacier catchment such as the Austre Lovenbreen inhigh resolution just in a few days or even…
Sedimentary Dynamics in Glacial and Proglacial Domains, Combe d’Ain, Jura (France), during the Last Glacial Maximum
2006
International audience
Snow studies in the Austre Lovén glacier basin, Kongsfjorden, Svalbard
2015
International audience
10 years of mass balance over a small Arctic basin. The example of Austre Lovénbreen (Svalbard)
2018
International audience