Éditeur(s) : HAL CCSD
Résumé : This work addresses a study of geodynamics in Armenia, a country located in the central part of the zone of continental collision between the Arabian and Eurasian lithosphere plates. The work includes two main parts: study of recent deformations of the lithosphere by means of GPS and detailed paleoseismological and morphometric investigations in the zone of the Artanish-Tskhouk segment of the PSSF. We analyze and compare rates of deformation determined by the GPS data and the rates estimated by the paleoseismological and morphometric studies. The Armenian-French network of GPS observations was installed in Armenia in 1998. Three observation sessions were conducted in 1998, 2000 and 2003. Based on the evidence obtained, a detailed study of the velocity field was conducted to analyze lithosphere deformation in Central and Northern Armenia. Slip rates were estimated for the principal active faults in Armenia. Several field works, including paleoseismological, archaeo-seismological, archaeological, geodetic and morphological studies, had been implemented in the zone of the Artanish-Tskhouk segment of the PSSF in 2003-2005. The fault was mapped in detail; rates of main horizontal and vertical slip along the fault were estimated and re-estimated. Four (4) paleo- and archeo-earthquakes were studied and dated. Eventually, the obtained data allowed us to re-estimate slip rates, maximum possible magnitudes and recurrence intervals of strong earthquakes on the Artanish-Tskhouk segment of the PSSF. A technique enabling estimation of horizontal and vertical displacements along strike-slip faults during paleo-earthquakes by the evidence obtained from paleo-seismological trenching was developed.
Les travaux présentés dans ce mémoire sont consacrés à l'étude de la géodynamique du territoire de l'Arménie qui est situé dans la partie centrale de la zone de collision continentale entre les plaques Arabique et Eurasienne. Le mémoire comprend deux parties principales: 1/ l'étude des déformations actuelles par la géodésie GPS; 2/ l'étude paléosismologique et morphométrique détaillée de la zone du segment d'Artanish-Tskhuk de la faille de Pambak-Sevan-Syunik (PSSF). On présente l'analyse et la comparaison des vitesses de déformations estimées par les données de GPS et par les données paléosismologiques et morphométriques. Le réseau d'observations GPS Arméno - Français a été installé en Arménie en septembre 1998. Trois campagnes de mesure du réseau ont été réalisées en 1998, 2000 et 2003. L'analyse détaillée du champ de vitesse à partir des données GPS a permis d'étudier et de quantifier les déformations actuelles de l'Arménie centrale et septentrionale. On a pu estimer les vitesses des déplacements des failles actives principales du territoire de l'Arménie. Un ensemble de travaux sur le terrain comprenant des recherches paléosismologiques, archéosismologiques, archéologiques, géodésiques, et morphologiques a été réalisé entre 2003 et 2005 dans la zone du segment d'Artanish-Tskhuk de la faille de PSSF. La cartographie détaillée de la faille a été réalisée et l'on a estimé et/ou re-estimés les déplacements horizontaux et verticaux le long de la faille. Quatre paléo- et archéoséismes ont été étudiés et datés. À partir des données obtenues, pour le segment d'Artanish-Tskhuk de la faille de PSSF, on a réévalué les vitesses de déplacements, la magnitude maximale possible, et l'intervalle récurrence des séismes forts. Une méthode d'évaluation des déplacements horizontaux et verticaux a été proposée à partir des logs de tranchées sur les failles de décrochements associées à des paléoséismes.
https://tel.archives-ouvertes.fr/tel-00551535

Droits : info:eu-repo/semantics/OpenAccess
tel-00551535
https://tel.archives-ouvertes.fr/tel-00551535
https://tel.archives-ouvertes.fr/tel-00551535/document
https://tel.archives-ouvertes.fr/tel-00551535/file/thesedavtyan2.pdf

Éditeur(s) : Springer
Résumé : The French Atlantic coast contains large highly productive intertidal mudflats that are colonised by juveniles of numerous flatfish species, including the common sole (Solea solea, L.). These ecosystems are also heavily exploited by the shellfish farming industry. Intensive bivalve culture is associated with substantial biodeposition (1-6 t-dw ha(-1) day(-1)), which directly or indirectly contributes to increase exopolysaccharide (EPS) concentrations at the interface between water column and seabed. EPS are long-chain molecules organised into colloids, which influence rheological properties of water, particularly viscosity. Increased water viscosity had consequences for ventilatory activity of juvenile flatfish, whereby the minimal pressure required to ventilate the medium increases directly with EPS concentration. Moreover, the critical EPS concentration ([EPS](crit)) at which water was no longer able to flow through the branchial basket ranged from almost nil to over 30 mg l(-1), depending on species and size. [EPS](crit) was lower in small individuals and individuals from species with high metabolic rates (turbot and plaice). These differences may depend upon gill and bucco-branchial cavity morphometrics. The ventilatory workload of sole increased with viscosity to a maximum at 2 mg EPS l(-1). Viscosity might, therefore, be a limiting factor for flatfish post larvae, which colonise the intertidal mudflats, depending upon their size and species. EPS concentrations in the field can reach 15 mg l(-1). A selective effect is conceivable but remains to be estimated in the field.
Marine Biology (0025-3162) (Springer), 2007-09 , Vol. 152 , N. 4 , P. 803-814

Droits : 2007 Springer
http://archimer.ifremer.fr/doc/2007/publication-2801.pdf
DOI:10.1007/s00227-007-0731-z
http://archimer.ifremer.fr/doc/00000/2801/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The nucleation and growth processes of spherulitic alkali feldspar have been investigated in this study through X-ray microtomography and electron backscatter diffraction (EBSD) data. Here we present the first data on Shape Preferred Orientation (SPO) and Crystal Preferred Orientation (CPO) of alkali feldspar within spherulites. The analysis of synchrotron X-ray microtomography and EBSD datasets allowed us to study the morphometric characteristics of spherulites in trachytic melts in quantitative fashion, highlighting the three-dimensional shape, preferred orientation, branching of lamellae and crystal twinning, providing insights about the nucleation mechanism involved in the crystallization of the spherulites. The nucleation starts with a heterogeneous nucleus (pre-existing crystal or bubble) and subsequently it evolves forming “bow tie” morphologies, reaching radially spherulitic shapes in few hours. Since each lamella within spherulite is also twinned, these synthetic spherulites cannot be considered as single nuclei but crystal aggregates originated by heterogeneous nucleation. A twin boundary may have a lower energy than general crystal–crystal boundaries and many of the twinned grains show evidence of strong local bending which, combined with twin plane, creates local sites for heterogeneous nucleation.This study shows that the growth rates of the lamellae (10− 6–10− 7 cm/s) in spherulites are either similar or slightly higher than that for single crystals by up to one order of magnitude. Furthermore, the highest volumetric growth rates (10− 11–10− 12 cm3/s) show that the alkali feldspar within spherulites can grow fast reaching a volumetric size of ~ 10 μm3 in 1 s.
ISSN: 0024-4937

hal-01172356
https://hal.archives-ouvertes.fr/hal-01172356
DOI : 10.1016/j.lithos.2014.12.003

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The growth of relief in active tectonic areas is mainly controlled by the interactions between tectonics and surface processes (erosion and sedimentation). The study of long-lived morphologic markers formed by these interactions can help in quantifying the competing effects of tectonics, erosion and sedimentation. In regions experiencing active extension, river-long profiles and faceted spurs (triangular facets) can help in un- derstanding the development of mountainous topography along normal fault scarps. In this study, we devel- oped analogue experiments that simulate the morphologic evolution of a mountain range bounded by a normal fault. This paper focuses on the effect of the fault slip rate on the morphologic evolution of the foot- wall by performing three analogue experiments with different fault slip rates under a constant rainfall rate. A morphometric analysis of the modelled catchments allows comparing with a natural case (Tunka half- graben, Siberia). After a certain amount of fault slip, the modelled footwall topographies of our models reaches a dynamic equilibrium (i.e., erosion balances tectonic uplift relative to the base level) close to the fault, whereas the topography farther from the fault is still being dissected due to regressive erosion. We show that the rates of vertical erosion in the area where dynamic equilibrium is reached and the rate of re- gressive erosion are linearly correlated with the fault throw rate. Facet morphology seems to depend on the fault slip rate except for the fastest experiment where faceted spurs are degraded due to mass wasting. A stream-power law is computed for the area wherein rivers reach a topographic equilibrium. We show that the erosional capacity of the system depends on the fault slip rate. Finally, our results demonstrate the pos- sibility of preserving convex river-long profiles on the long-term under steady external (tectonic uplift and rainfall) conditions.
ISSN: 0040-1951

hal-00646966
https://hal.archives-ouvertes.fr/hal-00646966
https://hal.archives-ouvertes.fr/hal-00646966/document
https://hal.archives-ouvertes.fr/hal-00646966/file/preprint_Strak_2011.pdf
DOI : 10.1016/j.tecto.2011.10.005

Éditeur(s) : HAL CCSD PeerJ
Résumé : International audience
The study of vertebrate ontogenies has the potential to inform us of shared developmental patterns and processes among organisms. However, fossilised ontogenies of early vertebrates are extremely rare during the Palaeozoic Era. A growth series of the Late Devonian ''acanthodian'' Triazeugacanthus affinis, from the Miguasha Fossil-Fish Lagerstätte, is identified as one of the best known early vertebrate fossilised ontogenies given the exceptional preservation, the large size range, and the abundance of specimens. Morphological, morphometric, histological and chemical data are gathered on a growth series of Triazeugacanthus ranging from 4 to 52 mm in total length. The developmental trajectory of this Devonian ''acanthodian'' is characteristic of fishes showing a direct development with alternating steps and thresholds. Larvae show no squamation but a progressive appearance of cartilaginous neurocranial and vertebral elements, and appendicular elements, whereas juveniles progress in terms of ossification and squamation. The presence of cartilaginous and bony tissues, discriminated on histological and chemical signatures, shows a progressive mineralisation of neurocranial and vertebral elements. Comparison among different body proportions for larvae, juveniles and adults suggest allometric growth in juveniles. Because of the phylogenetic position of ''acanthodians'', Triazeugacanthus ontogeny informs us about deep time developmental conditions in gnathostomes.
ISSN: 2167-8359

Droits : http://creativecommons.org/licenses/by/
hal-01633978
http://hal.upmc.fr/hal-01633978
http://hal.upmc.fr/hal-01633978/document
http://hal.upmc.fr/hal-01633978/file/peerj-3969.pdf
DOI : 10.7717/peerj.3969

Éditeur(s) : Elsevier
Résumé : Sea cruises were conducted for 57 days over 16 months to characterise pelagic fish aggregations around 2 moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). Echosounder surveys run in a star pattern were used in conjunction with obliquely beamed sonar observations. An echo-integration-by-shoal algorithm was implemented to isolate pelagic fish shoals from sound scattering layers and to compute mean morphometric, positional and density parameters. Tree regressions were used to select and classify pelagic fish Target Strengths (TS), with reference to their spatial and temporal characteristics. The main type of pelagic fish aggregation was a large sub-surface aggregation. It was observed during all daytime periods within a radius of 400 m of the FAD. A smaller type of aggregation was observed closer to the surface and to the FAD in 65% of daytime periods. Large scattered fish were observed in 16% of daytime periods. At night, a medium-sized aggregation was detected in the sub-surface in 75% of night-time periods. The sizes of the fish inside the aggregations (determined from TS values) were lower in the small near-surface aggregation than in the large sub-surface aggregation. Mean packing densities of sub-surface medium fish and near-surface small fish aggregations (determined from TS and shoal acoustic density) were respectively 0.2 fish per m3 and 1.3 fish per m3. The acoustic methodology and results are discussed with reference to the characteristics and performance of the echosounder and to the spatial structure of pelagic fish aggregations around moored FADs in Martinique.
Fisheries Research (0165-7836) (Elsevier), 2006-06 , Vol. 82 , N. 1-3 , P. 162-175

Droits : Elsevier 2006
http://archimer.ifremer.fr/doc/2006/publication-1734.pdf
DOI:10.1016/j.fishres.2006.06.025
http://archimer.ifremer.fr/doc/00000/1734/

Éditeur(s) : HAL CCSD
Résumé : The evolution of mountain belt piedmont is controlled by interactions between tectonics, erosion and sedimentation. To study coupling between these processes, we analyze morphometric data collected in the eastern Tian Shan piedmont (NW China) and develop a new analogue modelling technique. The modeling approach uses an experimental set-up and analog material specifically designed to study simultaneously tectonic structures (faults, folds), detailed morphology (drainage basins, channels, alluvial fans, etc.) and stratified sedimentation. Measurement techniques based on laser interferometry and image correlation are also developed to quantify the topographic and kinematic evolution of models.
Our experiments allow a new approach for the study of piedmont morphotectonic evolution. Our results indicate that tectonics mainly controls this evolution. The propagation of deformation and the formation of relief both significantly influence the development of drainage networks, the evolution of drainage basins and the formation of morphotectonic markers. Particularly, a study of alluvial fans and watershed metrics suggests that there is a dynamical equilibrium between uplift, erosion and morphology. In addition, our results show that terrace nucleation is controlled by thrust activity and hydrography adjustments. Folding of terraces responds to a homothetic deformation pattern.
This new methodology brings promising perspectives in the fields of geomorphology, seismotectonics and sedimentology.
L'évolution d'un piémont de chaîne de montagnes est contrôlée par les interactions entre la tectonique, l'érosion et la sédimentation. Pour étudier ces processus, nous avons analysé des données morphométriques issues des piémonts orientaux du Tian Shan (NW Chine) et développé un nouveau type de modélisation analogique. Cette approche utilise un dispositif et un matériau expérimental spécialement conçus pour modéliser simultanément des structures tectoniques (failles, plis), une morphologie détaillée (bassins versants, rivières, cônes alluviaux, etc.) et une sédimentation stratifiée. Des techniques de mesure optique ont été également mises en oeuvre afin de quantifier l'évolution topographique et cinématique des modèles.
Les expériences réalisées offrent une opportunité inédite d'étudier l'évolution morphotectonique d'un piémont. Nos résultats montrent que la tectonique exerce un contrôle de premier ordre sur cette évolution. La propagation de la déformation et la formation des reliefs influencent en effet significativement le développement du réseau de drainage, l'évolution des bassins versants et la formation des marqueurs morphotectoniques. En particulier, l'analyse de la morphométrie des cônes alluviaux et de leurs bassins versants suggère qu'un équilibre dynamique s'installe entre la surrection, l'érosion et la morphologie. Nos résultats montrent également que l'apparition des terrasses est guidée par l'activité des chevauchements et les adaptations de l'hydrographie. Leur modèle de plissement répond à une déformation homothétique.
Cette nouvelle approche ouvre des perspectives d'étude prometteuses en géomorphologie, sismotectonique et stratigraphie.
https://tel.archives-ouvertes.fr/tel-00339145

tel-00339145
https://tel.archives-ouvertes.fr/tel-00339145
https://tel.archives-ouvertes.fr/tel-00339145v2/document
https://tel.archives-ouvertes.fr/tel-00339145/file/These_Graveleau08.pdf

Éditeur(s) : HAL CCSD Kasetsart University
Résumé : http://www.ceropath.org/references/rodent_protocols_book
Technical book
"Protocols for field and laboratory rodent studies" present the best practices for the studies of rodents and rodent-borne pathogens and parasites from the field to the laboratory. It aims at covering the different steps of rodent studies: 1) Trapping, 2) Dissection and preparation of tissue samples for pathogens screening, 3) Identification of species, 4) Isolation of helminths, 5) Preparing rodent specimens for collections. This book gathers accurate recommendations and techniques, based on those generally accepted in the literature and adapted from the experience of the different authors during rodent surveys and laboratory work. Its presentation is designed to work in the fields with a clear and colorful organization of each chapter, with: inserts providing definitions and recommendations, protocols detailed step by step, and an emphasis on illustrations with several photographs. This book is a publication generated by the CERoPath project (Community Ecology of Rodents and their Pathogens in a changing environment, www.ceropath.org) funded by the French Ministry of Research from 2008 to 2011.
http://hal.ird.fr/ird-00714514

ird-00714514
http://hal.ird.fr/ird-00714514
http://hal.ird.fr/ird-00714514/document
IRD : fdi:010056183

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
The only symbiotic Mediterranean gorgonian, Eunicella singularis, has faced several mortality events connected to abnormal high temperatures. Since thermotolerance data remain scarce, heat-induced necrosis was monitored in aquarium by morphometric analysis. Gorgonian tips were sampled at two sites: Medes (Spain) and Riou (France) Islands, and at two depths: 15 m and-35 m. Although coming from contrasting thermal regimes, seawater above 28 degrees C led to rapid and complete tissue necrosis for all four populations. However, at 27 degrees C, the time length leading to 50% tissue necrosis allowed us to classify samples within three classes of thermal sensitivity. Irrespectively of the depth, Medes specimens were either very sensitive or resistant, while Riou fragments presented a medium sensitivity. Microsatellite analysis revealed that host and symbiont were genetically differentiated between sites, but not between depths. Finally, these genetic differentiations were not directly correlated to a specific thermal sensitivity whose molecular bases remain to be discovered.
ISSN: 1631-0691

hal-01546168
https://hal.archives-ouvertes.fr/hal-01546168
DOI : 10.1016/j.crvi.2013.06.008