Éditeur(s) : HAL CCSD
Résumé : International audience
L’Open hardware constitue la dernière extension du mouvement dit du « Libre » en propriété intellectuelle. Si l’Open hardware procède également du numérique, son objet est constitué d’un « matériel libre », soit une série d’objets physiques dont la production, la distribution et le partage sont déclarés libres par un modèle de licence similaire à celui des logiciels. La création collaborative irrigue désormais des créations purement matérielles,plus précisément corporelles.
Les écosystèmes numériques et la démocratisation informationnelle : Intelligence collective, Développement durable, Interculturalité, Transfert de connaissances
Schoelcher, France

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01265772
https://hal.univ-antilles.fr/hal-01265772
https://hal.univ-antilles.fr/hal-01265772/document
https://hal.univ-antilles.fr/hal-01265772/file/Philippe%20MOURON.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
EISSN: 1873-7803

hal-00530976
https://hal.archives-ouvertes.fr/hal-00530976
DOI : 10.1016/j.cageo.2010.01.001

Éditeur(s) : HAL CCSD
Résumé : Session "Posters"
National audience
Nous présentons une méthode permettant la mesure complète de la pose de la tête lors de captures vidéo monoculaires. Ce procédé utilise un modèle de visage et de texture précis. Le modèle facial, construit à partir d'une distribution de scans 3D haute résolution de visages, permet de générer des densités adaptées aux résolutions effectives. L'étape d'initialisation de la position du modèle est cruciale car elle conditionne le suivi ultérieur de la pose. Nous proposons ainsi d'utiliser une métrique composite construite sur des textures extraites de trois bases de données différentes. L'algorithme est alors capable de suivre le visage dans de vastes plages de poses avec une grande précision. Nous proposons des séquences vidéo de test dotées de vérité-terrain de pose précise et indépendante (précision de 0.1 degrés RMS)
Actes de la conférence RFIA 2012
Lyon, France

hal-00656565
https://hal.archives-ouvertes.fr/hal-00656565
https://hal.archives-ouvertes.fr/hal-00656565/document
https://hal.archives-ouvertes.fr/hal-00656565/file/rfia2012_submission_118.pdf

Éditeur(s) : HAL CCSD
Résumé : In an earlier paper, we developed an efficient incremental unknowns (IU) preconditioner for solving the two-dimensional (2D) Helmholtz problem in both high and low frequency (wavenumber) regimes. The multilevel preconditioning scheme involves separation of each grid into a coarser grid of the following level and a complementary grid on which the IUs are defined by interpolation. This approach is efficient as long as the mesh size of the coarsest grid is sufficiently small compared to the wavelength. In order to overcome this restriction, the authors introduced recently a modified IU method combining the conventional interpolation with the Helmholtz equation based interpolation (EBI). The EBI coefficients are derived numerically using a sufficiently large set of analytic solutions of the Helmholtz equation on a special hierarchy of stencils. The modified IUs using Helmholtz EBI are shown to provide improved preconditioning on the coarse scales where the conventional interpolation can not be employed. This study deals with the extension of this idea for solving the three-dimensional (3D) Helmholtz equation.
https://hal.univ-antilles.fr/hal-00763930

Droits : info:eu-repo/semantics/OpenAccess
hal-00763930
https://hal.univ-antilles.fr/hal-00763930
https://hal.univ-antilles.fr/hal-00763930/document
https://hal.univ-antilles.fr/hal-00763930/file/eci3D_3d.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
Aegean extension is a process driven by slab rollback that, since 45 Ma, shows a twostage evolution. From Middle Eocene to Middle Miocene it is accommodated by localized deformation leading to i) the exhumation of high-pressure metamorphic rocks from mantle to crustal depths, ii) the exhumation of high-temperature rocks in core complexes and iii) the deposition of Paleogene sedimentary basins. Since Middle Miocene, extension is distributed over the whole Aegean domain giving a widespread development of onshore and offshore Neogene sedimentary basins. We reconstructed this two-stage evolution in 3D at Aegean scale by using available ages of metamorphic and sedimentary processes, geometry and kinematics of ductile deformation, paleomagnetic data and available tomographic models. The restorationmodel shows that the rate of trench retreat was around 0.6 cm/y during the first 30 My and then accelerated up to 3.2 cm/y during the last 15 My. The sharp transition observed in the mode of extension, localized versus distributed, which occurred in Middle Miocene correlates with the acceleration of trench retreat and is more likely a consequence of the Hellenic slab tearing documented by mantle tomography. The development of large dextral NE-SW strike-slip faults during the second stage of Aegean extension, since Middle Miocene, is illustrated by the 450 Km-long fault, recently put in evidence, offshore from Myrthes to Ikaria and onshore from Izmir to Balikeshir, in western Anatolia. Therefore, the interaction between the Hellenic trench retreat and the westward displacement of Anatolia started in Middle Miocene,almost 10 Ma before the propagation of the North Anatolian Fault in the North Aegean. This raises a fundamental issue concerning the dynamic relationship between slab tearing and Anatolia displacement
ISSN: 0438-9557

insu-01574659
https://hal-insu.archives-ouvertes.fr/insu-01574659
https://hal-insu.archives-ouvertes.fr/insu-01574659/document
https://hal-insu.archives-ouvertes.fr/insu-01574659/file/EFFECTS_OF_SLAB_ROLLBACK_ACCELERATION_ON_AEGEAN_EX.pdf
DOI : 10.12681/bgsg.11697

Éditeur(s) : HAL CCSD Elsevier
Résumé : The Gulf of Aigues-Mortes (NW Mediterranean Sea) is a midshelf zone whose scale is an intermediate between the nearshore scale (0–10 m depth) and the coastal scale (including the whole continental shelf). Its hydrodynamics is investigated for the first time. ADCP, CTD and thermosalinograph data were collected during three short cruises (HYGAM; March 6–7, 20–21, April 5–6, 2005). They were scheduled approximately every 15 days to sample the gulf circulation under different weather conditions. Moreover, the cruise data were used to validate the Symphonie model, a 3D primitive equations circulation model. The circulation features displayed by in situ data were well reproduced by Symphonie. A downscaling modelling approach was implemented, the largest scale being obtained by the replay of the MFSTEP regional model of the North-Western Mediterranean Sea. The analysis, closely coupling in situ measurements and model results, provides information that would not have been obtained using data separately. The great variability of the oceanic circulation at this scale is well evidenced. Winds are the main forces, not only locally but also at a larger scale. North winds generate coherent structures interacting with the general Mediterranean circulation. The explanation of the induced currents is then not straightforward, some of them being, for example, northward. South and southeast winds reinforce the sloping surface, the latter allowing the geostrophic equilibrium with longshore currents. This study, focused on the end of winter 2004–2005, also enhances the heat fluxes from offshore to nearshore, as well as the initiation of shelf dense waters. The knowledge of the midshelf oceanic circulation is then applied to run a numerical experiment which describes both the dispersion of a fictive contaminant from a point S (at the centre of the GAM), and evaluates the risk of contamination of the beaches along the GAM shores.
ISSN: 0278-4343

hal-00196620
https://hal.archives-ouvertes.fr/hal-00196620
DOI : 10.1016/j.csr.2007.06.006

Éditeur(s) : HAL CCSD National Research Council Canada
Résumé : International audience
Back-arc extension in the Aegean, which was driven by slab rollback since 45 Ma, is described here for the first time in two stages. From Middle Eocene to Middle Miocene, deformation was localized leading to i) the exhumation of high-pressure metamorphic rocks to crustal depths, ii) the exhumation of high-temperature metamorphic rocks in core complexes and iii) the deposition of sedimentary basins. Since Middle Miocene, extension distributed over the whole Aegean domain controlled the deposition of onshore and offshore Neogene sedimentary basins. We reconstructed this two-stage evolution in 3D and four steps at Aegean scale by using available ages of metamorphic and sedimentary processes, geometry and kinematics of ductile deformation, paleomagnetic data and available tomographic models. The restoration model shows that the rate of trench retreat was around 0.6 cm/y during the first 30 My and then accelerated up to 3.2 cm/y during the last 15 My. The sharp transition observed in the mode of extension, localized versus distributed, in Middle Miocene correlates with the acceleration of trench retreat and is likely a consequence of the Hellenic slab tearing documented by mantle tomography. The development of large dextral NE-SW strike-slip faults, since Middle Miocene, is illustrated by the 450 Km-long fault zone, offshore from Myrthes to Ikaria and onshore from Izmir to Balikeshir, in western Anatolia. Therefore, the interaction between the Hellenic trench retreat and the westward displacement of Anatolia started in Middle Miocene, almost 10 Ma before the propagation of the North Anatolian Fault in the North Aegean.
ISSN: 0008-4077

insu-01271296
https://hal-insu.archives-ouvertes.fr/insu-01271296
https://hal-insu.archives-ouvertes.fr/insu-01271296/document
https://hal-insu.archives-ouvertes.fr/insu-01271296/file/Brun%20etal%20CJES%202016.pdf
DOI : 10.1139/cjes-2015-0203

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Wallace (1951) and Bott (1959) were the first to introduce the idea that the slip on each fault surface has the same direction and sense as the maximum shear stress resolved on that surface. However, this simplified hypothesis is questionable since fault mechanical interactions may induce slip reorientations. Earlier numerical geomechanical models confirmed that the slickenlines (slip vectors) are not necessarily parallel to the maximum resolved shear stress but are consistent with local stress perturbations. This leads us to ask as to what extent the Wallace and Bott simplifications are reliable as a basis hypothesis for stress inversion from fault slip data. Here, a geomechanical multi-parametric study using a 3D boundary element method, covering (i) fault geometries such as intersected faults or corrugated fault surfaces, (ii) the full range of Andersonian state of stress, (iii) fault friction, (iv) fault fluid pressure, (v) half space effect and (vi), rock properties, is performed in order to understand the effect of each parameter on the misfit angle between geomechanical slip vectors and the resolved shear stresses. It is shown that significant misfit angles can be found under specific configurations invalidating the Wallace and Bott assumptions, even though fault friction tends to minimize the misfit. We therefore conclude that in such cases, stress inversions based on fault slip data should be interpreted with care.
ISSN: 0040-1951

hal-01218418
https://hal.archives-ouvertes.fr/hal-01218418
DOI : 10.1016/j.tecto.2015.06.030

Éditeur(s) : HAL CCSD Elsevier
Résumé : The seismic characteristics of focused fluid-related features such as pockmarks and carbonate build-ups on the Nigerian continental slope have been investigated using complementary seismic data sets (reprocessed 3D exploration data and 2D Very High Resolution hull-mounted and near-bottom seismic data) coupled with the results of previous studies (sedimentological, geotechnical and geochemical analyses).The results show different types of fluid-related features within the hemipelagic phase of long duration (∼1 Myr) Turbidite/Hemipelagic cycles. They are the product of the disturbance of the hosting sediments following two main distinct processes: (1) no or low sediment deposition caused by fluid escape associated with seafloor settlement (benthic fauna, carbonate precipitation, gas hydrate formation) and (2) post-depositional erosion, caused either by fluid release (dewatering from underlying features such as channels and upward migration from a deep source) or by collapse (destabilisation of gas hydrates). The temporal evolution reveals a decrease in fluid flow during the hemipelagic deposition as witnessed by the decrease in methanogenic activity and by gas hydrate destabilisation. The spatial distribution of fluid-related features seems to be controlled by the type of fault (small fault or structural lineament).
ISSN: 0264-8172

hal-01685513
https://hal.archives-ouvertes.fr/hal-01685513
DOI : 10.1016/j.marpetgeo.2017.10.004

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
From 15 to 17 June 2011, a dedicated workshop was held on the subject of in vitro models for mammalian spermatogenesis and their applications in toxicological hazard and risk assessment. The workshop was sponsored by the Dutch ASAT initiative (Assuring Safety without Animal Testing), which aims at promoting innovative approaches toward toxicological hazard and risk assessment on the basis of human and in vitro data, and replacement of animal studies. Participants addressed the state of the art regarding human and animal evidence for compound mediated testicular toxicity, reviewed existing alternative assay models, and brainstormed about future approaches, specifically considering tissue engineering. The workshop recognized the specific complexity of testicular function exemplified by dedicated cell types with distinct functionalities, as well as different cell compartments in terms of microenvironment and extracellular matrix components. This complexity hampers quick results in the realm of alternative models. Nevertheless, progress has been achieved in recent years, and innovative approaches in tissue engineering may open new avenues for mimicking testicular function in vitro. Although feasible, significant investment is deemed essential to be able to bring new ideas into practice in the laboratory. For the advancement of in vitro testicular toxicity testing, one of the most sensitive end points in regulatory reproductive toxicity testing, such an investment is highly desirable.
ISSN: 0890-6238

hal-00876979
https://hal.archives-ouvertes.fr/hal-00876979
DOI : 10.1016/j.reprotox.2013.04.004
PUBMED : 23612449

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Second harmonic generation (SHG) microscopy is a powerful tool for studying submicron architecture of muscles tissues. Using this technique, we show that the canonical single frequency sarcomeric SHG intensity pattern (SHG-IP) of premetamorphic xenopus tadpole tail muscles is converted to double frequency (2f) sarcomeric SHG-IP in metamorphic climax stages due to massive physiological muscle proteolysis. This conversion was found to rise from 7% in premetamorphic muscles to about 97% in fragmented muscular apoptotic bodies. Moreover a 66% conversion was also found in non-fragmented metamorphic tail muscles. Also, a strong correlation between predominant 2f sarcomeric SHG-IPs and myofibrillar misalignment is established with electron microscopy. Experimental and theoretical results demonstrate the higher sensitivity and the supra resolution power of SHG microscopy over TPEF to reveal 3D myofibrillar misalignment. From this study, we suggest that 2f sarcomeric SHG-IP could be used as signature of triad defect and disruption of excitation–contraction coupling. As the mechanism of muscle proteolysis is similar to that found in mdx mouse muscles, we further suggest that xenopus tadpole tail resorption at climax stages could be used as an alternative or complementary model of Duchene muscular dystrophy.
ISSN: 1047-8477

hal-01134174
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134174
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134174/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01134174/file/Recher%20et%20al_JSB-2015_hal.pdf
DOI : 10.1016/j.jsb.2015.03.003

Éditeur(s) : HAL CCSD Linnean Society of London
Résumé : International audience
The circumscription of Salicaceae has recently been enlarged to include a majority of the species formerly placed in the polyphyletic tropical family Flacourtiaceae. Several studies have reported a peculiar and infrequently formed multilayered structure of tension wood in four of the tropical genera. Tension wood is a tissue produced by trees to restore their vertical orientation, and most studies have focused on trees developing tension wood by means of cellulose-rich, gelatinous fibres, as is known in Populus L. and Salix L. (Salicaceae s.s.). This study aims to determine if the multilayered structure of tension wood is an anatomical characteristic common in other Salicaceae, and if so, how its distribution correlates to phylogenetic relationships. Therefore, we studied the tension wood of 14 genera of Salicaceae as well as two genera of Achariaceae, one genus of Goupiaceae, and one genus of Lacistemataceae, families closely related to Salicaceae or formerly placed in Flacourtiaceae. Opposite wood and tension wood were compared with light microscopy and 3D Laser Scanning Confocal Microscopy. The results indicate that a multilayered structure of tension wood is common in the family except in Salix, Populus, and one of their closest relatives, Idesia polycarpa Maxim. We suggest that tension wood may be a useful anatomical character in understanding phylogenetic relationships in Salicaceae. Further investigation is still needed on the tension wood of several other putatively close relatives of Salix and Populus, in particular Bennettiodendron Merr., Macrohasseltia L.O.Williams and Itoa Hemsl.
ISSN: 0024-4074

hal-01392845
https://hal.archives-ouvertes.fr/hal-01392845
https://hal.archives-ouvertes.fr/hal-01392845/document
https://hal.archives-ouvertes.fr/hal-01392845/file/GhislainEtAl2016_MultylayerTWSalicaceae_Bot_Jsur the_Lin_Soc_HALssfig.pdf
DOI : 10.1111/boj.12471

Éditeur(s) : HAL CCSD
Résumé : International audience
o abstract
Coastal Engineering Proceedings

hal-01426586
https://hal.archives-ouvertes.fr/hal-01426586

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Among persisting questions on bone calcification, a major one is the link between protein expression and mineral deposition. A cell culture system is here proposed opening new integrative studies on biomineralization, improving our knowledge on the role played by non-collagenous proteins in bone. This experimental in vitro model consisted in human primary osteoblasts cultured for 60 days at the surface of a 3D collagen scaffold mimicking an osteoid matrix. Various techniques were used to analyze the results at the cellular and molecular level (adhesion and viability tests, histology and electron microscopy, RT-and qPCR) and to characterize the mineral phase (histological staining, EDX, ATG, SAED and RMN). On long term cultures human bone cells seeded on the osteoid-like matrix displayed a clear osteoblast phenotype as revealed by the osteoblast-like morphology, expression of specific protein such as alkaline phosphatase and expression of eight genes classically considered as osteoblast markers, including BGLAP, COL1A1, and BMP2. Von Kossa and alizarine red allowed us to identify divalent calcium ions at the surface of the matrix, EDX revealed the correct Ca/P ratio, and SAED showed the apatite crystal diffraction pattern. In addition RMN led to the conclusion that contaminant phases were absent and that the hydration state of the mineral was similar to fresh bone. A temporal correlation was established between quantified gene expression of DMP1 and IBSP, and the presence of hydroxyapatite, confirming the contribution of these proteins to the mineralization process. In parallel a difference was observed in the expression pattern of SPP1 and BGLAP, which questioned their attributed role in the literature. The present model opens new experimental possibilities to study spatio-temporal relations between bone cells, dense collagen scaffolds, NCPs and hydroxyapatite mineral deposition. It also emphasizes the importance of high collagen density environment in bone cell physiology.
ISSN: 1932-6203

hal-01142641
http://hal.upmc.fr/hal-01142641
http://hal.upmc.fr/hal-01142641/document
http://hal.upmc.fr/hal-01142641/file/Silvent_2013_Collagen.pdf
DOI : 10.1371/journal.pone.0057344

Éditeur(s) : HAL CCSD
Résumé : International audience
Aegean extension is a process driven by slab rollback that since 45 Ma shows a two-stage evolution. From 45 to13 Ma it is accommodated by localized deformation leading to i) the exhumation of high-pressure metamorphicrocks from mantle to crustal depths, ii) the exhumation of high-temperature rocks in core complexes and iii) thedeposition of Paleogene sedimentary basins. Since 13 Ma, extension is distributed over the whole Aegean domaingiving a widespread development of onshore and offshore Neogene sedimentary basins. The 3D reconstruction atAegean scale of this two-stage evolution shows that the rate of trench retreat was around 0.6 cm/y during the first30 My and then accelerated up to 3.2 cm/y during the last 13 My. Using available tomographic evidence, timingof metamorphic and sedimentary processes, paleomagnetic data and geometry and kinematics of deformation, wepropose that the sharp transition in trench retreat and deformation mode, localized vs distributed, at 13 Ma wascontrolled to slab tearing. Moreover, the development of dextral NE-SW strike-slip faults and related pull-apartbasins in the North Aegean domain, from the Cyclades to the Rhodope, strongly suggests that this sharp transitionalso corresponds to the onset of Anatolia westward escape.
Geophysical Research Abstracts
Vienne, Austria

insu-01137631
https://hal-insu.archives-ouvertes.fr/insu-01137631

Éditeur(s) : HAL CCSD
Résumé : Gravitropism is a major process in vertical growth as it allows the positioning of plant in the gravity field and thus, for trees, it takes part in the light foraging strategies. Without any gravitropism, trees would adopt a weeping habit or fall on the ground due to the increasing with growth supported weight, especially at the advance regeneration stage (sapling stage) in the understorey, where tree are very slender and poorly stiff. Most of the gravitropic studies are made by physiologists in order to understand the process and thus are associated to complex laboratory methods (genetic engineering, anatomical studies, accurate 2D ou 3D measurements of form changes with time). In order to study the ecological relevance and the specific diversity of gravitropic performances in natural forests, we developed a framework that uses different kinds of datas. Synchronical analysis has been done i) at the population level in large sample of trees and ii) at the tree level from destructive measurement of the dissymmetry maturation strains known to be the main motor of the posture control reaction of trees. In both cases, biomechanical models allows to estimate some aspects of the dynamic gravitropic process. Diachronical analysis has been done in natural conditions on permanent plots, or in a more traditional way, by observing in greenhouse experiments the righting movements of plants artificially tilted. In the first case, the problem is the high variability of natural disturbances and the slowness of growth and movements in the dark understorey. The second choice allows a measurement of a capacity (i.e. the ability of the species to react in quite extreme conditions of verticality disturbance but good for growth light and nutrient conditions) that is more easy to analyse, but is maybe not so relevant for estimating the ecological strategy (some species could have developed a high efficience of gravitropic reaction in natural conditions by avoiding the mechanical disturbance or adapting the reaction to slow growth and changing environments in natural conditions). All approaches use the same basic biomechanical modelling, i) to analyse simultaneously the reaction and the disturbance (due to the weight increase) during growth, or ii) to combine different parameters (geometry, growth, weight, maturation strains) involved in shape changes and posture control. They give a classification of the species according to their gravitropic performances. Results on 15 species are discussed, with relation to shade-tolerance or avoidance.
6th Plant Biomechanics Conference
Cayenne, France

hal-00565956
https://hal.archives-ouvertes.fr/hal-00565956

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Giant Gjallar Vent (GGV), located in the Vøring Basin off mid-Norway, is one of the largest (~ 5 × 3 km) vent systems in the North Atlantic. The vent represents a reactivated former hydrothermal system that formed at about 56 Ma. It is fed by two pipes of 440 m and 480 m diameter that extend from the Lower Eocene section up to the Base Pleistocene Unconformity (BPU). Previous studies based on 3D seismic data differ in their interpretations of the present activity of the GGV, describing the system as buried and as reactivated in the Upper Pliocene. We present a new interpretation of the GGV's reactivation, using high-resolution 2D seismic and Parasound data. Despite the absence of geochemical and hydroacoustic indications for fluid escape into the water column, the GGV appears to be active because of various seismic anomalies which we interpret to indicate the presence of free gas in the subsurface. The anomalies are confined to the Kai Formation beneath the BPU and the overlying Naust Formation, which are interpreted to act as a seal to upward fluid migration. The seal is breached by focused fluid migration at one location where an up to 100 m wide chimney-like anomaly extends from the BPU up to the seafloor. We propose that further overpressure build-up in response to sediment loading and continued gas ascent beneath the BPU will eventually lead to large-scale seal bypass, starting a new phase of venting at the GGV.
ISSN: 0025-3227

hal-01054142
https://hal.archives-ouvertes.fr/hal-01054142
DOI : 10.1016/j.margeo.2014.03.006

Éditeur(s) : HAL CCSD
Résumé : International audience
The carbon capture and storage is considered as one of the solutions of reducing the effects of global warming. It consists in injecting large quantities of CO 2 in supercritical form directly into deeply located geological formations. One of the methods involves sequestration in the carbonate sedimentary rocks (sandstones and limestones) which are considered as a promising solution. The morphology of the pore network and solid skeleton defines important macroscopic prop-erties of the rock (permeability, stiffness). Modelling at micro scale of random heterogeneous materials (porous media) should be based on morphological and statistical characterisation 1,2 of the investigated microstructure. The work is focused on a reconstruction method by grains deposit 3 , for various range of pa-rameters, to obtain equivalent model of natural rock samples (oolitic limestone and fontainebleau sandstone). Generated samples satisfy morphological and statistical informations 4 which were obtained by 3D image analysis of X-ray tomography of the natural rock samples. For validation of the modelling numerical computations of mechanical and transfer properties are also provided.
14th European Mechanics of Materials Conference - EMMC14
Gothembourg, Sweden

hal-01103163
https://hal.archives-ouvertes.fr/hal-01103163

Éditeur(s) : HAL CCSD Taylor & Francis: STM, Behavioural Science and Public Health Titles
Résumé : International audience
The dislocation microstructures in a single crystal of olivine deformed experimentally in uniaxial compression at 1090 °C and under a confining pressure of 300 MPa, have been investigated by transmission electron tomography in order to better understand deformation mechanisms at the microscale relevant for lithospheric mantle deformations. Investigation by electron tomography reveals microstructures, which are more complex than previously described, composed of and dislocations commonly exhibiting 3D configurations. Numerous mechanisms such as climb, cross-slip, double cross-slip as well as interactions like junction formations and collinear annihilations are the source of this complexity. The diversity observed advocates for microscale deformation of olivine significantly less simple than classic dislocation creep reported in metals or ice close to melting temperature. Deciphering mechanism of hardening in olivine at temperatures where ionic diffusion is slow and is then expected to play very little role is crucial to better understand and thus model deformation at larger scale and at temperatures (900–1100 °C) highly relevant for the lithospheric mantle.
ISSN: 1478-6443

hal-01667146
https://hal.archives-ouvertes.fr/hal-01667146
DOI : 10.1080/14786435.2017.1367858

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : International audience
A NE-SW magnetotelluric 110 km-long profile including 18 sites was acquired across the western Rif Cordillera along the Eurasian-African plate boundary, allowing to constrain its poorly known deep structure. It extends from the Internal Zones, close to the Alboran coast, crossing the External Zones and up to the Gharb foreland basin. The periods recorded range from 0.001 s to 1000 s. The combination of magnetotelluric data with available geological data provides new insight regarding the relationship between deep and shallow crustal structures of the Rif Cordillera. Analyses of structural dimensionality suggest a preferential NW-SE direction, and a 2D joint inversion was performed. A 3D inversion extending the 2D model along the strike confirmed the reliability of this approach. The magnetotelluric model shows a heterogeneous upper crust in agreement with the geological structures observed at surface. The Internal Zones correspond to resistive (metamorphic rocks) and conductive (peridotites) bodies, while the External Zones and the foreland basin are characterized by large conductive bodies of variable thickness. A crustal detachment level separating shallow geological units from a probable variscan basement was inferred. At depth, the most relevant feature consists of large resistive bodies with a shallow irregular top, located below the frontal part of the Rif. The outcrops of exotic metapelitic, granitic and gneissic blocks in the frontal part of the Cordillera suggest that these large resistive bodies may correspond to a gneissic or granitic basement surrounded by metapelitic rocks. Late contractive thrust and diapiric processes were responsible for their uplift and shallow emplacement. The Rif constitutes an active southwestward vergent orogenic wedge, oblique to the present-day NW-SE convergent Eurasian-African plate boundary.
ISSN: 1525-2027

hal-00670999
https://hal.archives-ouvertes.fr/hal-00670999
DOI : 10.1029/2011GC003783