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Conference: 1st International Conference on Mapping and Spatial Analysis of Socio-Economic and Environmental Indicators for the Local and Regional Sustainable Development (SEE GEOMATICS)Location: Tataouine, TUNISIADate: MAR 25-26, 2015; International audience; For mapping the three-dimensional shape of the submarine bars, studying their dynamics and assessing the spatiotemporal evolution of sedimentary balances, the coastal prism of Korba (emerged and submerged beach) has benefitted from topo-bathymetric monitoring. This monitoring was carried out on an annual basis between July 2006 and July 2009. Numerical Terrain Models (N.T.M.) and transverse profiles were then analyzed. The main results show, firstly, that the shoreface of Korba is characterized by a homogeneous evolution across all profiles of its two-bar system. Moreover, the extent of changes in the sand volume of the beach suggests that the evolution takes place without significant sedimentary loss and that the beach is in a dynamic equilibrium. Accretion of the bars and migration towards the shore are found in periods of small waves (between July 2006 and July 2007). However, following a period of minor agitations, a filling of the outer trough is observed. It is proceeded by the migration of the outer bar towards the coast (between July 2007 and July 2009). These results confirm the traditional model of self-organization of a barred beach. These data and results, then, allow us to establish conceptual models and simulations of the evolution of the microtidal, barred beach of Korba.

Introduction The modern Afro-Asian porcupines, the African cane-, mole- and dassie-rats, as well as the South American guinea pigs, chinchillas, capybaras, pacas, agoutis, etc., make up the natural group of the hystricognathous rodents (infra-order Hystricognathi Tullberg, 1899). The phylogenetic relationships between the hystricognaths from South America (caviomorphs (Caviomorpha Wood, 1955)) and Africa (phiomorphs (Phiomorpha sensu Lavocat, 1967; Thryonomyoidea sensu Wood, 1955)) are today well-supported by a body of anatomical (e.g. Wood, 1974; Lavocat, 1976; Bugge, 1985; George, 1985; Meng, 1990; Luckett and Hartenberger, 1993; Martin, 1994) and molecular (e.g. Nedbal et al ., 1996; Huchon and Douzery, 2001; Huchon et al ., 2002, 2007; Poux et al ., 2006; Montgelard et al ., 2008; Blanga-Kanfi et al ., 2009; Churakov et al ., 2010) evidence, and also by endoparasite studies (e.g. Hugot, 1999). In contrast, the phylogenetic and geographic origins of hystricognaths have been the subject of considerable controversy over the past several decades (e.g. Wood and Patterson, 1959; Hoffstetter, 1972; Wood, 1972, 1973, 1974, 1985; Lavocat, 1973, 1974, 1976; Hussain et al ., 1978; Flynn et al ., 1986; Jaeger, 19; Huchon and Douzery, 2001, 2002; Marivaux et al ., 2002, 2004; Jaeger et al ., 2010a), and critical issues about their historical biogeography, notably their arrival in South America, are still a matter of on-going debate (e.g. Poux et al ., 2006; Bandoni de Oliveira et al ., 2009; Sallam et al ., 2009, 2011; Coster et al ., 2010; Antoine et al ., 2012). Although hystricognaths are absent from the earliest Tertiary fossil record at a global scale, their earliest known fossil occurrences date back to the late middle Eocene from both Africa and South America. This either suggests that hystricognaths have rapidly achieved a widespread distribution throughout the Old and New Worlds just after their emergence, or points out the existence of a significant Eocene gap in their fossil record. During the late Eocene and early Oligocene, the group exhibited a high diversity and morphological disparity on both landmasses, thereby suggesting a considerable amount of undocumented diversity in their early evolutionary history.

The superconducting gravimeter (SG) uses magnetic levitation as a stable gravity spring and is the default relative instrument for observatory gravity. SGs have high precision (~ 0.01 μGal), exceptional calibration stability (~ 0.01%), low drift (few μGal per year), and record at periods from 1 s to years. The newest iGrav SG is transportable in a small SUV, requires no liquid helium, has integrated electronics, and is easy to set up. We review instrument design, reduction and data processing, and many applications: seismic modes; tides and nutations; large- and small-scale atmospheric, oceanic, and hydrologic loading; volcanology; coseismic signals; and time-variable gravity exploration.

Publisher Summary This chapter reviews that the knowledge of the extent of quaternary glaciers in the Himalayan mountains of Nepal, based on the accumulated evidence, still remains very fragmentary. However, Nepal occupies a significant central position in the Himalayan mountain chain, with 8 peaks over 8000 m high and with extensive regions over 6500 m a.s.1. Access to the country is quite variable. It discusses that several areas of the highest massifs provides the highest mountain climbing and walking stations in the world and are well served by a dense network of footpaths and resting places. However, to gain access to some valleys north of the high chain requires several days walk and special expensive permits to enter. This explains the reason certain regions are effectively terra incognita from the perspective of quaternary glaciations. The chapter also provides an overview on a model that shows the different possible glaciation scenarios that are controlled by the topography and the position of study sites in the Himalaya chain. It also includes the limits used for the reconstruction of past glaciations. It discusses that isolated massifs, separated from the highest massifs and the processes imposed by the proximity to steep rock walls were occupied through the quaternary by small ice caps. These places hold the most important evidence for understanding qaternary glacial fluctuations. However, they have received little attention, because they are far from the major communication routes and too close to the Tibetan border.

International audience; The study area mainly includes the continental shelves of two European states (France and Spain), three North African countries (Algeria, Morocco and Tunisia), and Gibraltar and Monaco. Overall, the total shelf area in the western Mediterranean down to the 150 m isobath is 208,000 km2 within a total basin area of 1,343,620 km2. There is a major difference in the degree of available information from EU member states and North African countries.

International audience; Three-dimensional modelling tools are used with structural and palaeomagnetic analysis to constrain the tectonic history of part of the Dauphiné zone (external Western Alps). Four compressive events are identified, three of them being older than the latest Oligocene. Deformation D1 consists of W–SW directed folds in the Mesozoic cover of the study area. This event, better recorded in the central and southern Pelvoux massif, could be of Eocene age or older. Deformation D2 induced N-NW-oriented basement thrusting and affected the whole southern Dauphiné basement massifs south of the study area. The main compressional event in the study area (D3) was WNW oriented and occurred before 24 Ma under a thick tectonic load probably of Penninic nappes. The D2-D3 shift corresponds to a rapid transition from northward propagation of the Alpine collision directly driven by Africa-Europe convergence, to the onset of westward escape into the Western Alpine arc. This Oligocene change in the collisional regime is recorded in the whole Alpine realm, and led to the activation of the Insubric line. The last event (D4) is late Miocene in age and coeval with the final uplift of the Grandes Rousses and Belledonne external massifs. It produced strike-slip faulting and local rotations that significantly deformed earlier Alpine folds and thrusts, Tethyan fault blocks and Hercynian structures. 3D modelling of an initially horizontal surface, the interface between basement and Mesozoic cover, highlights large-scale basement involved asymmetric folding that is also detected using structural analysis. Both, Jurassic block faulting and basement fold-and-thrust shortening were strongly dependent on the orientation of Tethyan extension and Alpine shortening relative to the late Hercynian fabric. The latter's reactivation in response to oblique Jurassic extension produced an en-échelon syn-rift fault pattern, best developed in the western, strongly foliated basement units. Its Alpine reactivation occurred with maximum efficiency during the early stages of lateral escape, with tectonic transport in the overlying units being sub-perpendicular to it.

International audience; During the Paleocene–Eocene, the Earth experienced the warmest conditions of the Cenozoic and reduced equator-to-pole temperature gradients. Compared to low- and mid-latitude sites, Paleogene environmental changes are less documented in Arctic regions, although such high latitude areas constitute a critical domain to constrain global climate changes. Floral and faunal assemblages indicative of exceptionally warm and humid conditions during the late Paleocene–early Eocene have been reported in several localities around the Arctic Ocean. Additional studies are required to ascertain the effects of Paleocene–Eocene global environmental changes on western Arctic regions. Here we present multiproxy data from early Eocene deltaic plain sediments of the Mackenzie Delta (Canada). This environment is characterized by littoral forest, including swamp, showing that the mangrove Avicennia grew in Arctic Canada near 75°N under air temperatures averaging 21–22 °C annually and 10–14 °C in winter and with precipitation of 1200–1400 mm/yr. Kaolinite contents are high (up to 75% of clay assemblages), as under a modern subtropical climate. The Avicennia pollens recently found in the New Siberian Islands and in Arctic Canada imply that warm and wet conditions were widespread along the Arctic coast during the early Eocene. It also suggests a marine connection between the Arctic Basin and the mid-latitude oceans. We propose that an oceanic current must have connected the Arctic Basin to the Atlantic and/or Pacific and that an internal current developed in the Arctic Basin since the early Eocene.

International audience; On the basis of immobile trace elements and Nd isotope signatures, the Barrandian meta-basalts may be ascribed to two major groups, extracted from contrasting mantle sources: A depleted group, with strong light rare earth element depletion, elevated Zr/Nb ratios (>30), and highly radiogenic Nd isotopes (Nd600 from +7.8 to + 9.3). Multi-element patterns normalized to normal mid-ocean ridge basalt all show negative anomalies of Nb, and to a lesser degree, Zr and Ti. Eight samples may define a 605 ± 39-Ma whole-rock isochron with Ndi of +8.8 ± 0.2. An enriched group, comprising both mildly enriched (Zr/Nb 12–18) and strongly enriched (Zr/Nb 4–7) samples, with Nd600 ranging from +8.2 to +3.8. The depleted group is interpreted to reflect generation from depleted mantle sources fluxed by subduction-related components, probably in an intraoceanic back-arc basin. In contrast, the younger enriched group is typical of the within-plate style of mantle enrichment and documents the extinction of the subduction-related component. The switch from suprasubduction zone to within-plate magmatism suggests that new mantle material flowed into the former arc and back-arc system sources. This flow might have occurred simply as a result of ocean-ward migration of the subduction zone. Alternatively, the subduction fluxing might have stopped as a result of impingement of a spreading ridge with the intraoceanic trench, leading to mutual annihilation, a switch to a transform plate boundary, and opening of a slab window that allowed the inflow of new mantle and the generation of late-stage, within-plate enriched basalts. In terms of modern analogues, the Neoproterozoic of the Barrandian and other Cadomian regions of western Europe resemble arc and back-arc systems from the western Pacific region, where large intraoceanic subduction systems fringe major continental masses with a complex mosaic of microplates and magmatic arcs, including intervening basins floored either by oceanic crust or attenuated continental crust.

International audience

Of the features that characterize large shield volcanoes on Mars, flank terraces remain the most enigmatic. Several competing mechanisms have been proposed for these laterally expansive, topographically subtle landforms. Here we test the hypothesis that horizontal contraction of a volcano in response to the down-flexing of its underlying basement leads to flank terracing. We performed a series of analogue models consisting of a conical sand–plaster load emplaced on a basement comprising a layer of brittle sand–plaster atop a reservoir of viscoelastic silicone. Our experiments consistently produced a suite of structures that included a zone of concentric extension distal to the conical load, a flexural trough adjacent to the load base and convexities (terraces) on the cone’s flanks. The effects of variations in the thickness of the brittle basal layer, as well as in the volume, slope and planform eccentricity of the cone, were also investigated. For a given cone geometry, we find that terrace formation is enhanced as the brittle basement thickness decreases, but that a sufficiently thick brittle layer can enhance the basement’s resistance to loading such that terracing of the cone is reduced or even inhibited altogether. For a given brittle basement thickness, terracing is reduced with decreasing cone slope and/or volume. Our experimental results compare well morphologically to observations of terraced edifices on Mars, and so provide a framework with which to understand the developmental history of large shield volcanoes on the Red Planet.