Éditeur(s) : HAL CCSD
Résumé : Carbon and Oxygen isotope profiles from a well-dated carbonate section spanning the Sinemurian time on the Caussenard High (southeast France) are compared to sedimentological data and the results from sequence stratigraphy analysis, in order to discuss the origin of isotopic variations in a shallow-marine carbonate succession. The sedimentological study has enabled the identification of four types of depositional environments (peritidal, lagoonal, sand shoal, outer-shelf) that formed meter-scale cycles. The latter are arranged in two third-order cycles whose boundaries correspond to distinct δ13C and δ18O negative peaks (at the end of the Hettangian time and during Middle Sinemurian). The origin of the isotopic signals is discussed and several hypothesis are envisaged: sea water ageing, early meteoric diagenesis. Isotopic curves observed here seems to be related to early meteoric diagenesis linked to variations of third-order sea-level cycles rather than environmental factors (temperature, salinity).
Swiss Journal of Geosciences

hal-00406603
https://hal.archives-ouvertes.fr/hal-00406603
DOI : 10.1007/s00015-007-1206-4

Éditeur(s) : Pêche thonière et dispositifs de concentration de poissons, Caribbean-Martinique, 15-19 Oct 1999
Résumé : Yellowfin tuna (Thunnus albacares) is a main target for the fisheries at Fish Aggregating Devices (FADs) off the south of Okinawa island. Catch and weight composition of the tuna were monitored at a fisheries cooperative market from 1989 to 1998. Some distinct weight groups (considered to represent cohorts) appeared in the catch and the weight of these groups increased monthly - presumably as individual tuna grew. Although small, light weight fish were caught year-round, the 2 kg weight group that was recruited in May grew to about 15 kg by May of the next year. There was a significant seasonal cycle in the monthly catches. The catch of heavier weight groups decreased in winter indicating the tuna moved out of this FAD area. At one of huge FADs (Nirai), fifteen nautical miles southeast of Okinawa island (depth about 1.300 m), a current meter (Aanderaa RCM-7) recorded current and water temperature from June 1995 to March 1996. The current meter was attached to the FAD at 4 m depth. When typhoons attacked Okinawa, the water temperature drastically dropped. Typically, average current speed was 29 cm/s and eastward current was most frequent. Being affected by tide, the current was averaged over twenty-five hours. Current speed was correlated with the yellowfin catch in 120 daily sets at the FAD; the weaker the current speed, the greater the catch. Although not significant, the catch was greater with northeastward current than with southwestward current.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00042/15300/12662.pdf
http://archimer.ifremer.fr/doc/00042/15300/

Éditeur(s) : HAL CCSD Geological Society of America
Résumé : International audience
We present a regional model of plate geometry and kinematics of Southeast Asia since the Late Cretaceous, embedded in a global plate model. The model involves subduction polarity reversals and sheds new light on the origin of the subduction polarity reversal currently observed in Taiwan. We show that this subduction zone reversal is inherited from subduction of the proto–South China Sea plate and owes its current location to triple junction migration and slab rollback. This analysis sheds new light on the plate tectonic context of the Taiwan orogeny and questions the hypothesis that northern Taiwan can be considered an older, more mature equivalent of southern Taiwan.
ISSN: 0091-7613

hal-01397683
https://hal.archives-ouvertes.fr/hal-01397683
DOI : 10.1130/G37821.1

Éditeur(s) : Gauthier-Villars
Résumé : Pegasus current measurements carried out along a section located off French Guiana are presented; the section was repeated five times from September 1989 to June 1991 during the NOE (region Nord-Ouest equatoriale)/STACS (Sub Tropical Atlantic Climate Studies) cruises on board the NOAA (National Oceanographic and Atmospheric Administration) research vessels. The data (vertical and horizontal distributions) show, as suggested by earliest observations, the presence of different currents. At the surface, and in winter, the North Brazil Current (NBC) flows northwestward (positive), is strong (120 cm/s), confined in the first 250 m, coastally trapped (within 250 km) and fed by offshore waters; in summer the NBC strengthens (the velocity increases to 150 cm/s), vertically extends (down to 800 m) and veers offshore; the mean NBC mass flux computed from all the sections available is 34 +/- 9 Sv with absolute maximum and minimum respectively in September 1989 (81 +/- 4 Sv) and February 1990 (13 +/- 1 Sv). Subsurface, a southeastward (negative) undercurrent (herein after named Western Boundary UnderCurrent) is present in winter-spring and located in the layer 250-800 m with similar velocities in February 1990 (- 33 cm/s) and June 1991 (- 29 cm/s) but with largest vertical and horizontal extensions in the latter case; in summer (September 1989 and September 1990) this undercurrent is absent; the mean mTBUC mass flux is - 9 +/- 3 Sv; the maximum is observed in June 1991 (- 19 +/- 2 Sv) and the minimum in February 1990 (- 3 +/- 0.4 Sv) and January 1991 (- 5 +/- I Sv). Deeper, the equatorward Deep Western Boundary Current is trapped against the continental shelf (within 100 km of the shelf break), extends downward from 1 200 to 3 000 m depth with the velocity core centred in the 1 700-2 000 m layer, is maximum (- 50 cm/s) in spring-summer and minimum (- 23 cm/s) in winter; the absolute velocity (- 92 cm/s) has been recorded at 2 000 m depth in September 1989 suggesting a strong variability at this level; the mean equatorward DWBC mass flux is - 30 +/- 14 Sv with absolute maximum and minimum respectively in September 1989 (- 59 +/- 6 Sv) and September 1990 (- 7 +/- 1 Sv). The Integrated Mass, Temperature and Salt Fluxes (IMF, ITF and ISF) with the cumulated errors, computed across the whole section and down to 3 000 m depth for the September 1990, January 1991 and June 1991 cruises, are all positive in September 1990 (respectively 1.9 +/- 19 Sv, 3.1 +/- 30.1 PW and 74 +/- 1 845 Tt/s) but all negative both in January 1991 (- 13.3 +/- 17.0 Sv, - 15.6 +/- 26.5 PW and - 478 +/- 1594 Tt/s) and June 1991 (- 3.8 +/- 10.1 Sv, - 4.0 +/- 16.3 PW, - 130 +/- 989 Tt/s) showing a strong variability between the summer and winter periods. The mean IMF, ITF and ISF values (respectively - 5.1 +/- 46.4 Sv, - 5.2 +/- 73 PW and - 178 +/- 4428 Tt/s) are high and negative, indicating the large influence of the DWBC and the associated North Atlantic Deep Water (upper part) off French Guiana at 5 degrees N.
Oceanologica Acta (0399-1784) (Gauthier-Villars), 1994 , Vol. 17 , N. 2 , P. 143-157

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00098/20881/18495.pdf
http://archimer.ifremer.fr/doc/00098/20881/

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
The nucleation, propagation, and associated folding of ramp-flat-ramp normal faults were analyzed from field examples developed in a brittle/ductile multilayer sequence of the Huércal-Overa Basin (SE Spain). Gently dipping sandy silt layers, which display a low cohesive strength (C0 = 7 kPa, μ = 34°), favor the development of extensional detachments. A tectonic origin instead of a possible gravitational origin is supported by the perpendicularity between the paleoslope direction of the fluvial-deltaic environment inferred from imbricated pebbles, and the senses of movement deduced from fault slicken-lines. The link between high-angle normal faults (HANFs) --formed at different levels in the layered sequence-- with horizontal fault segments comes to develop ramp-flat-ramp normal faults with associated roll-over in the hanging wall. Observed extensional duplexes are formed by parallel detachments connected through synthetic Riedel faults. These Riedel faults would produce the back-rotation of the individual blocks (horses), i.e., extensional folding of the originally subhorizontal layers. There is no correlation between the analyzed ramp-flat-ramp normal faults, accommodating south-southeastward extension during Serravallian-lower Tortonian, and either the regional Alpujarride/Nevado-Filabride west-directed extensional shear zone or the top-to-the-north detachments within Alpujarride units, which are clearly sealed by Serravallian-lower Tortonian sediments. Therefore, the studied normal faults are restricted to the brittle/ductile multilayer fluvio/deltaic sequence and accommodate moderate late extension instead of belonging to a large crustal extensional system connected with a regional detachment at depth. Therefore, the basin formed in a moderate crustal thickness context where small and medium-scale extensional systems were subordinate structures. These natural examples support the development of low-angle normal faults at very shallow crustal levels in multilayer sequences with suitable rheological conditions.
ISSN: 0278-7407

hal-00750352
https://hal.archives-ouvertes.fr/hal-00750352
DOI : 10.1029/2012TC003130

Éditeur(s) : The American Association of Petroleum Geologlists
Résumé : The west African continental margin between Abidjan (Ivory Coast) and Walvis Boy (Southwcst Africa) was surveyed in 1971 by the R/V Jean Charcot. Fiftyeight seismic-reflection (flexotir source), bathymetric (3.5 and 12 kc), gravimetric, and magnetic profiles were obtained. The seaward limit of an evaporitic zone outlined during the survey is at the boundary between continental slope and continental rise. Variation of depth of this limit as a function of latitude shows the presence of a large offset at 11°S which seems to be related to an east-east-southeast line of magnetic seamounts cutting into the continental slope. The Annobon-Cameroun volcanic axis separates the salt zones of the Nigerian basin and Congo-Angola basin. The northern limit of Salt deposition in the Congo-Angola basin is marked near 1°N by a strong southwest-northeast magnetic trend. On the south it extends to necr 14°s. The Walvis Ridge, located farther south, does not seem to have an effect on evaporite deposition. [NOT CONTROLLED OCR]
The American Association of Petroleum Geologlists Bulletin (The American Association of Petroleum Geologlists), 1973 , Vol. 57 , N. 9 , P. 1658-1671

Droits : The American Association of Petroleum Geologlists
http://archimer.ifremer.fr/doc/1973/publication-5123.pdf
http://archimer.ifremer.fr/doc/00000/5123/

Éditeur(s) : HAL CCSD Société géologique de France
Résumé : New radiolarian assemblages of Late Jurassic age were extracted from seven chert localities of the basement comp ex of La Desirade Island (Guadeloupe), the oldest geological unit of the Lesser Antilles arc and the eastern Caribbean region. These fauna range in age from Kimmeridgian or early Tithonian to early or early late Tithonian, showing that La Desirade cherts are not all coeval, contrary to what was established by previous studies. Furthermore, the close spatial association of cherts and volcanic elements composed of basaltic flows and volcaniclastics suggests a mixed setting of hydrothermal siliceous deposits and biogenous sedimentation consistent with an arc-related oceanic setting rather than an ophiolite-type oceanic crust. As the Youngest age is obtained to the northwest of the basement complex where as older data are found to the southeast, it also Suggests that La Desirade basement complex may have undergone some structural stacking consistent with an accretion-type geodynamic getting. Our biochronological data provide a preliminury try tectonic model of an eastward subduction zone for Lesser Antilles arc basement emplacement during the Mesozois.
EISSN: 1777-5817

hal-00445252
https://hal.archives-ouvertes.fr/hal-00445252
DOI : 10.2113/gssgfbull.180.5.399

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
This paper presents a paleo-hydrological study conducted on sediment flood deposits at two sites located in the Gardon Gorges, Southeast France. The first study site is a valley‑side terrace (referred to as site GE, located 10m above the channel bed) and the second is located in a cave (referred to as site GG, perched 15m above the bed level). Paleo‑flood events were identified by carefully analyzing each slackwater flood deposits. The flood units were then dated using a variety of dating techniques, namely 137Cs, 210Pbex, 14C geochemical analysis of mining‑contaminated slackwater flood sediments, archeological objects and the historic flood record. Hydraulic modeling was also carried out in order to verify the coherence between the stratigraphic records of flood deposits at the sites and the historic flood levels known along the river Gardon. It is demonstrated that all the major flood events of the 20th century can be identified at terrace GE. This type of geomorphological unit can therefore be used as a sound basis for a paleo-hydrological analysis of the Gardon Gorges. Furthermore, the analysis of the stratigraphic record at site GG demonstrates that the site can be used to trace the largest flood events that have occurred within the past 600 years. The study reveals that the frequency of extreme flood events increased during the Little Ice Age
Une étude paléo-hydrologique a été entreprise dans les Gorges du Gardon, où deux coupes sédimentaires ont été étudiées. La première provient d'une terrasse (coupe GE située à 10 m de hauteur au dessus de la rivière) et l'autre, d'une cavité (coupe GG localisée à 15 m au-dessus de la rivière). L'identification et la mise en évidence des différents paléo-événements de crue ont été établies grâce à l'inspection minutieuse de chaque dépôt sédimentaire et d'une étude géochronologique fine (137Cs, 210Pbex, 14C, métaux traces, objets archéologiques, historiques des crues). Nous avons souhaité évaluer la capacité des terrasses fluviatiles du Gardon à enregistrer des paléo-événements en comparant les coupes sédimentaires aux données historiques des hauteurs d'eau et aux résultats d'un modèle hydraulique 1D. Nous montrons que la terrasse GE enregistre la quasi-totalité des évènements du 20ème siècle et qu'à priori, ce type d'objet géomorphologique peut être utilisé pour toute étude paléo-hydrologique sur le Gardon. De plus, l'étude de la coupe GG (cavité perchée à 15 m) permet de reconstituer les évènements intenses au cours des 600 dernières années. Nous montrons une augmentation des crues extrêmes dans le Haut-Languedoc au cours du "Petit âge glaciaire".
ISSN: 0018-6368

hal-01108400
https://hal.archives-ouvertes.fr/hal-01108400
https://hal.archives-ouvertes.fr/hal-01108400/document
https://hal.archives-ouvertes.fr/hal-01108400/file/ly2014-pub00041935.pdf
DOI : 10.1051/lhb/2014037

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
This paper presents a synthesis of a multidisciplinary study carried out along the Nîmes Roman aqueduct, located in the southeast part of France. The study was motivated by archaeologists attempting to explain the partial destructions of only one aerial bridge of the aqueduct (Pont de la Lône). Given its close proximity to the Nîmes seismically active fault, a possible seismic origin for the destructions was invoked. Seismologists and structural engineers thus carried out a variety of field and numerical investigations to test the seismic hypothesis. Supporting field evidence was found first along the aerial bridge section of the aqueduct: broken stalactites, arch warping, cracks and destruction of the bridge just above a breast wall shortly after its construction. Secondly, the underground part of the canal was analysed: irregularity in the thickness of calcite deposits of the canal walls, presence of numerous cracks, horizontal shift of the otherwise linear structure of the canal and presence of calcite twins in the deposits, found only where the canal crosses the Nîmes fault system. Numerical modelling and experimental results show that (1) only the Pont de la Lône would have suffered serious damage under seismic solicitation (assuming an M6 earthquake at 10 km distance). The second aerial bridge, the three levels arches Pont du Gard, an historical monument still standing today, would have suffered less damage, due to its very different fundamental frequency of around 0.4 Hz, far from the amplified seismic near-field spectrum; (2) the numerical models also show that a fall of the canal wall would require a higher magnitude event (M > 6); (3) the presence of calcite twinning requires a differential static stress of 4 MPa or greater, which can only be achieved very close to the fault rupture of a M > 6 earthquake; (4) finally, local surface rupturing of such a fault would also corroborate the hypothesis that the observed offset of the canal may be partly seismically induced. Although other possible origins for each individual evidence may not be excluded, the observed spatiotemporal concentration of architectural/geological anomalies together with the numerical results allow us to support a possible co-seismic origin for these disorders, indirectly attesting to the potential seismic activity (M > 6) of the nearby Nîmes fault. Furthermore, following the conclusions of archaeological studies, the disorders occurred between 250 and 350 year AD, thus providing timing for this possible seismic event, an essential parameter in seismic hazard analysis. These results validate the archaeo-seismological approach as a tool that may help improve the knowledge of major infrequent earthquakes in areas of moderate seismic activity.
ISSN: 0921-030X

hal-00379064
https://hal.archives-ouvertes.fr/hal-00379064
DOI : 10.1007/s11069-008-9276-9

Éditeur(s) : Elsevier
Résumé : Previous studies conducted on the continental shelf in the Southeast Bay of Biscay influenced by Gironde waters (one of the two largest rivers on the French Atlantic coast) showed the occurrence of late winter phytoplankton blooms and phosphorus limitation of algal growth thereafter. In this context, the importance of dissolved organic phosphorus (DOP) for both algae and bacteria was investigated in 1998 and 1999 in terms of stocks and fluxes. Within the mixed layer, although phosphate decreased until exhaustion from winter to spring, DOP remained high and phosphate monoesters made up between I I to 65% of this pool. Total alkaline phosphatase activity (APA, V-max) rose gradually from winter (2-8 nM h(-1)) to late spring (100-400 nM h-1), which was mainly due to an increase in specific phytoplankton (from 0.02 to 3.0 nmol mu gC(-1) h(-1)) and bacterial APA (from 0.04 to 4.0 nmol mu gC(-1) h(-1)), a strategy to compensate for the lack of phosphate. At each season, both communities had equal competitive abilities to exploit DOP but, taking into account biomass, the phytoplankton community activity always dominated (57-63% of total APA) that of bacterial community (9-11%). The dissolved APA represented a significant contribution. In situ regulation of phytoplanktonic APA by phosphate (induction or inversely repression of enzyme synthesis) was confirmed by simultaneously conducted phosphate-enrichment bioassays. Such changes recorded at a time scale of a few days could partly explain the seasonal response of phytoplankton communities to phosphate depletion.
Journal of Experimental Marine Biology and Ecology (0022-0981) (Elsevier), 2005-05 , Vol. 318 , N. 2 , P. 213-225

Droits : 2005 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2005/publication-608.pdf
DOI:10.1016/j.jembe.2004.12.017
http://archimer.ifremer.fr/doc/00000/608/

Éditeur(s) : HAL CCSD
Résumé : The Deep Basin of the Gulf of Mexico (DBGM) extends over eastern Mexico, the southeastern part of the United States, west of the Atlantic Ocean. This study, based on the interpretation and integration of seismic profiles, exploration wells and outcrop studies, focus on the deep part of the Gulf of Mexico, where bathymetry varies from 200 to 3750 m, thus comprising both the continental slope and the abyssal plain. The first part of this thesis focus on the description of the sedimentary infill of the western part of the Gulf of Mexico, in the Veracruz State, and to its geodynamic controls. The geodynamic evolution of the Deep Basin of the Gulf of Mexico (DBGM) begins during the Triassic-Jurassic with the break-up and the opening of a continental rift, in the southern part of the North American lithospheric plate. This opening induced a relative movement of the Yucatan Block towards the southeast. This intra-continental rifting episode was followed by a stage of post-rift thermal subsidence in the basins of the continental margin in the west, coeval with oceanic accretion in the DBGM. The thermal subsidence of the margin was subsequently modified by the Laramian orogeny, which impacted strongly the overall architecture of the margin as well as its litho-stratigraphic evolution, inducing the deposition of siliciclastic deposits in various morphotectonic provinces: i.e., near the tectonic front of the Sierra Madre Oriental (SMO), within the adjacent Chicontepec foreland basin, over the Tuxpan Platform (Golden Lane), across the continental slope and up to the deep abyssal plain, these two last morphotectonic provinces belonging to the DBGM. During the Early Paleogene, the effects of the thermal subsidence of the passive margin were stressed by the tectonic load of the Laramian orogen (i.e., the Sierra Madre Oriental, SMO), thus allowing the development of a foreland basin flexural. In this geodynamic framework, the main sedimentary transfers developed from the tectonic front "SMO" in the west, towards the DBGM in the east, the main source for clastic sediments being linked to the erosion of the "SMO" mountains. During the Paleocene and the Early Eocene, the architecture of the silici-clastic syn-tectonic sediments deposited in submarine fans was characterized by sliding, turbidites with A and B Bouma facies, as well as levees and channels. After the stop of the flexural subsidence, the thermal subsidence of the passive margin resumed during the Late Eocene, the Oligocene and the Neogene, allowing the development of a new sedimentary prism, prograding eastwards toward the DBGM. This sedimentary infill was again made up of levees-channels, sand bars and delta systems. During the Neogene, an extensional system with listric faults and roll-over features developed across the slope of the DBGM, due to an active detachment developing within overpressured Eocene-Oligocene clays. This gravitational gliding of Neogene series accounted also for the development of compressional features at the toe of the slope. Approximately 60% of the Miocene siliciclastic sediments have been trapped in growth strata and slope basins associated with this complex gravitational system, ranging from river-delta features towards gravity slides associated with slump facies. The second part of this thesis aims at a quantification of these various processes, including the construction of balanced cross sections, forward Thrustpack kinematic modelling coupling the development of a basal detachment, lithospheric flexure, erosion and sedimentation, as well as subsequent stratigraphic modelling with the Dionisos software, the later aiming at predicting the sand versus clay ratios in Neogene siliciclastic deposits of the DBGM and its surroundings.
Le bassin profond du Golfe du Mexique (BPMG) est localisé à l'est du Mexique, au sud-est des États-Unis et à l'ouest de l'Océan Atlantique. Cette étude de la partie profonde du Golfe du Mexique est basée sur l'intégration de données de sismique, de forages pétroliers et d'études de terrain; elle comprend toute la pente continentale et la plaine abyssale, avec une bathymétrie qui varie de 200 à 3750 m. La première partie de cette thèse est consacrée à la description du remplissage sédimentaire de la bordure occidentale du Golfe du Mexique, dans le secteur de Veracruz, en liaison avec son évolution géodynamique. L'évolution géodynamique du BPMG commence au Trias-Jurassique avec la rupture et la propagation d'un rift continental, dans le secteur sud de la plaque nord américaine. Cette ouverture et le déplacement relatif vers le sud-est du bloc crustal du Yucatan sont à l'origine du BPGM. Cette géodynamique de rift continental est suivie d'une étape post-rift accompagnée de l'océanisation du bassin. Les bassins de la marge passive ont poursuivi leur évolution sous l'effet de la subsidence thermique à l'ouest du Golfe du Mexique, tandis que de la croûte océanique se formait dans le BPGM. Cette subsidence thermique de la marge a ensuite été perturbée par l'orogénèse Laramienne, qui a remodelé l'architecture stratigraphique silico-clastique des dépôts du Tertiaire entre les éléments morphotectoniques suivants: lefront tectonique de la Sierra Madre Orientale (SMO), le bassin d'avant-pays Chicontepec, la Plateforme de Tuxpan-Faja de Oro, la pente continentale et la plaine abyssale, ces deux dernières provinces morphotectoniques appartenant au BPGM. Pendant le Paléogèneinférieur, les effets de la subsidence thermique de la marge passive ont été accentués par la charge tectonique de l'orogénèse laramienne (SMO), permettant ainsi le développement d'un bassin flexural d'avant-pays. Au cours de cette étape, les principaux transferts sédimentaires se sont effectués du front tectonique "SMO" vers le BPGM. La source principale de sédiments clastiques est liée à l'érosion de la chaîne de montagnes "SMO". Pendant le Paléocène et l'Éocène inférieur, l'architecture des premiers sédiments silico-clastiques syn-tectoniques déposés dans des éventails sous-marins sont caractérisés par des figures de glissement, des faciès turbiditiques A et B de Bouma, des chenaux-levées. Après l'arrêt de la subsidence flexurale, la subsidence thermique de la marge passive s'est poursuivie pendant l'Éocène supérieur, l'Oligocène et le Néogène, permettant le développement d'un nouveau prisme sédimentaire progradant. Les remplissages sédimentaires sont encore constitués de chenaux et de levées, avec des barres de sable associées à des systèmes deltaïques sur la plateforme. Pendant le Néogène, un système de failles listriques s'est développé sur la pente du BPGM, au-dessus d'une surface de décollement située, dans la région d'étude, dans les argiles de l'Éocène-Oligocène. Ce système de failles de croissance a piégé plus de 60% des sédiments silico-clastiques du Miocène. Ce remplissage sédimentaire évolue latéralement de faciès fluviaux deltaïques vers des faciès de pente affectés de glissements gravitaires et associés à des turbidites. La deuxième partie de cette thèse est consacrée à une approche quantitative basée sur des modélisations structurales (coupes équilibrées et modélisations cinématiques directes avec Thrustpack, couplant décollement gravitaire, flexure lithosphérique, érosion et sédimentation), puis sédimentaires (prise en compte des transferts de matériel clastique depuis la partie émergée de la chaîne jusqu'au bassin profond, à l'aide du logiciel Dionisos, afin de mieux comprendre les processus de piégeage des sédiments grossiers dans les structures de croissance et les bassins perchés de la marge.
https://tel.archives-ouvertes.fr/tel-00435120

tel-00435120
https://tel.archives-ouvertes.fr/tel-00435120
https://tel.archives-ouvertes.fr/tel-00435120/document
https://tel.archives-ouvertes.fr/tel-00435120/file/thesealzaga.pdf

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : The environment is impacted by natural and anthropogenic disturbances that occur at different spatial and temporal scales, and that lead to major changes and even disequilibria when exceeding the resiliency capacities of the ecosystem. With an annual mean flow of 1700 m(3) s(-1), the Rhone River is the largest of the western Mediterranean basin. Its annual solid discharges vary between 2 and 20 Mt, with flood events responsible for more than 70% of these amounts. In the marine coastal area, close to the mouth, both flocculation and aggregation lead to the formation of fine-grained deposits, i.e. the prodelta. This area is characterized by sediment accumulation rates up to 20-50 cm yr(-1) and high accumulations of particle reactive contaminants such as various man-made radionuclides released into the river by nuclear facilities or arising form prior atmospheric nuclear tests (1954-1980) and the Chernobyl accident (April 1986). This prodelta, however, cannot be considered as a permanent repository for particle reactive pollutants since it is subjected to reworking processes. Sediment dynamics had to be linked to the influences of hydrodynamic and atmospheric events such as high flow rates or storms close to the Rhone River mouth. An experiment was carried out during the winter 2006 based on the deployment of two ADCPs and six altimeters at the Grand Rhone mouth for several months. This type of installation has never been used before in this area because of the hard meteorological conditions and the strong fishing activities. However, results showed pluricentimetric rises of the sedimentary level just after river flood events and decreases during storms, generated by southeast winds. Radiotracers and grain size depth profiles helped to characterise the studied events and to establish inventories of sediments and radionuclides. A cruise (CARMEX) was carried out during this same period to collect water samples, suspended particles and sediment cores. The results enabled us to link both river flow and wind characteristics to events recorded on the sea floor, i.e. resuspension, accumulation, consolidation, etc. Deposits of 11 cm of sediments were estimated during flood periods and bottom shear stresses up to 5 N m(-2) were calculated during sediment erosion phases. (C) 2010 Elsevier Ltd. All rights reserved.
Continental Shelf Research (0278-4343) (Pergamon-elsevier Science Ltd), 2010-05 , Vol. 30 , N. 9 , P. 1095-1107

Droits : 2010 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00006/11695/8479.pdf
DOI:10.1016/j.csr.2010.02.015
http://archimer.ifremer.fr/doc/00006/11695/

Éditeur(s) : La recherche face aux pêches artisanales
Résumé : Each of nine people agreed to write a summary regarding changes in research on small-scale fishing in a large region of the world. These summaries that will be presented to you focus respectively on changes in research in Southeast Asia, in the South Pacific along the western coast of Latin America, in West Africa, in the Mediterranean, in Northwest Europe, and in North America. In order to help you reconstruct their actions in the halieutic context of the regions about which they are talking, Serge Garcia will first present us with a panorama of small-scale fishing. By asking them to do this study, we wished to be able to place the symposium's study within an overall framework and in an historical perspective. The objective was to relativise the conclusions that could be drawn from analyses of local situations, or, on the contrary, to allow them to be generalised by using bases of comparison. The summaries are far from being able to offer a planetary geographical coverage, just as they do not really include the evolution of all disciplines. The means available to the organisers did not allow for going up to that point. We must at this point thank the authors who agreed to do this complex work of summarisation, because they succeeded in showing the richness of such a step, which the participants will be able to appreciate in their reports. In this analysis of geographical syntheses, we would like to draw a few comparisons able to fuel the symposium's debates. We will examine how small-scale fishing became a subject of research, and the difficulty of defining it. Then we will see how the various disciplines became mutually involved, then specialised, depending upon the stages through which the research passed on this subject. The role of institutions and the weight of the contextual environment will be examined. Finally, we will propose a few possible directions for the debates on various themes of the symposium. Some outside contributions to the summaries also focus on the evolution of the research and we have taken that into account in this presentation. Limited to one country (Yahaya Jahara) or to one province (Maneschy and Furtado), they are useful complements to the summaries.
(OCR non controlé) Neuf personnes ont accepté de rédiger chacune une synthèse concernant l'évolution des recherches sur les pêches artisanales dans une grande région du monde. Les synthèses qui vont vous être présentées portent respectivement sur l'évolution des recherches en Asie du Sud-Est, dans le Pacifique-sud sur la façade occidentale de l'Amérique Latine, en ,Afrique de l'Ouest, en Méditerranée, en Europe du Nord- Ouest, en Amérique du Nord. Pour vous permettre de resituer leurs interventions dans le contexte halieutique des régions dont ils nous parlent, Serge Garcia nous présentera en premier lieu un panorama des pêches artisanales. En leur demandant ce travail, nous avons souhaité pouvoir replacer les travaux du symposium dans un cadre global et dans une perspective historique. L'objectif était de relativiser les conclusions qui pourraient être tirées d'analyses de situations locales, ou, au contraire, de permettre leur généralisation en disposant de bases de comparaison. Les synthèses sont loin d'offrir une couverture géographique planétaire, tout comme elles n'intègrent pas vraiment l'évolution de toutes les disciplines. Les moyens à la disposition des organisateurs ne permettaient pas d'aller jusque là. Il nous faut remercier ici les auteurs qui ont consenti à faire ce travail complexe de synthèse, car ils ont réussi à démontrer la richesse d'une telle démarche, ainsi que les participants pourront l'apprécier à travers leurs exposés. Dans cette analyse des synthèses géographiques, nous voudrions tenter quelques comparaisons de nature à alimenter les débats du symposium. Nous examinerons comment est née la pêche artisanale en tant qu'objet de recherche, et la difficulté de la définir. Puis nous verrons, en fonction des étapes par lesquelles sont passées les recherches sur ce sujet, comment les différentes disciplines se sont mutuellement impliquées, puis se sont spécialisées. Le rôle des institutions et le poids des contextes seront examinés. Enfin nous proposerons quelques orientations possibles pour les débats sur les différents thèmes du symposium. Certaines contributions extérieures aux synthèses portent aussi sur l'évolution des recherches et nous en avons tenu compte dans cette présentation. Limitées à un pays (Yahaya Jahara) ou à une province (Maneschy et Furtado), elles complètent utilement les synthèses.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/1990/acte-2464.pdf
http://archimer.ifremer.fr/doc/00000/2464/

Éditeur(s) : HAL CCSD Elsevier
Résumé : Iron content of the bulk marine sediment from the Chilean continental margin has been used to infer millenial-scale climate changes in southeast Pacific [Lamy, F., Klump, J., Hebbeln, D., Wefer, G., 2000. Rapid climate change in northern Chile over the last 80 ka recorded in a marine sediment core. Terra Nova 12: 8–13]. Changes of iron contents have been related to a varying contribution of Andean (Fe-rich) versus Coastal Range (Fe-poor) source rocks ultimately controlled by continental rainfall changes. However, variations observed could also be produced by changes in the proportions of two components in the sediment — a detrital component with low and constant Fe content and an authigenic phase (Fe oxide, pyrite, apatite, etc.) with high Fe content. A sequential extraction has been used to partition the total iron content in the sediment of core GeoB 7101 at the continental margin of Chile. The extraction steps included five fractions: exchangeable, bound to carbonates, bound to Fe–Mn oxides, bound to organic matter, and residual. Iron appeared to be mainly present in the residual fraction, i.e. in the detrital component. Our study indicates that total Fe or Fe/Al may be used to infer millenial-scales climate changes in the southeastern Pacific.
ISSN: 0025-3227

hal-00407253
https://hal.archives-ouvertes.fr/hal-00407253
DOI : 10.1016/j.margeo.2007.03.006

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 SpringerOpen
Résumé : The Karakorum Fault zone (KFZ) plays an important role in understanding the formation, evolvement and deformation of the Tibetan Plateau. The high-T dextral shearing metamorphic rocks, e.g., mylonites or mylonitized gneisses-granites, locally crop out along the southeastern part of the KFZ in the Ayila Ri'gyü Range area. The SHRIMP U-Pb dating of the syn-kinematic crystallized zircons indicates that the initial age of the KFZ is ∼27 Ma, ∼10 Ma older than previous results. The extensive high-T dextral shearing along the KFZ started at least at 27–20 Ma, accompanied by the syn-kinematic emplacement of leuco-granites. Deformation and concomitant fluid circulation during shearing most likely occurred as early as at 25–13 Ma. The KFZ probably grew from southeast to northwest along the fault as a result of continuous convergence between the India plate and Eurasia plate.
ISSN: 1001-6538

hal-00406402
https://hal.archives-ouvertes.fr/hal-00406402
DOI : 10.1007/s11434-007-0164-6

Éditeur(s) : HAL CCSD
Résumé : In 1996 the European Commission Humanitarian Office (ECHO) launched a regional approach for disaster preparedness, focusing in its first phase on Central America, Caribbean and Southeast Asia (including Bangladesh). The first step in this process was the preparation of a «diagnostic study» that involved a situation review of the countries in these regions with regard to their vulnerabilities, disaster preparedness capacities and national plans or policies for disaster management.The Centre for Research on the Epidemiology of Disasters of the Université Catholique de Louvain (UCL) served as ECHO’s principal technical support with the collaboration of other institutions in Europe and the regions.The present «diagnostic report», covering Central America and the Caribbean, has been carried out by the Centre International pour la Formation et les Echanges en Géosciences (CIFEG) under the supervision of Professor Robert D’Ercole (Université de Savoie, Chambéry).Mr. Thierry Lesales (Université des Antilles et de la Guyane) participated closely in the drafting of this report and was actively involved in the field missions with Mr D’Ercole where they met and interviewed numerous national officials, non-governmental organisations and regional and international bodies. Further assistance was provided by Claudine Misson (CRED) for the interviews and information collected in the Dominican Republic. The report also draws from an earlier mission undertaken by Dr. Philippe Masure (BRGM, France), Christian Bugnion (CRED) and Alexandra Angulo (CRED) who undertook some of the preparatory work for the diagnostic study.This report presents an analysis of the disaster preparedness situation in Central America and the Caribbean and provides some preliminary recommendations regarding priorities and future programme direction. As such it remains primarily a descriptive study. It is expected to form the basis for the formulation of the ECHO Disaster Preparedness Action Plan.
En 1996, la Oficina Humanitaria de la Comunidad Europea (ECHO) lanzó la iniciativa de un enfoque regional en materia de preparación a los desastres, concentrándose inicialmente en las regiones de América Central, Caribe y Asia del Sureste (incluyendo a Bangladesh). La primera fase de este proceso fue la preparación de un « diagnóstico» que implicaba un examen de la situación de los países de cada una de estas regiones en relación a la vulnerabilidad, la capacidad de preparación a los desastres y las políticas y planes nacionales en materia de gestión de desastres.El Centre for Research on the Epidemiology of Disasters (CRED), de la Université Catholique de Louvain (UCL), ha sido el principal apoyo técnico de ECHO para esta iniciativa, con la colaboración y asistencia de otras instituciones en Europa y en las regiones arriba mencionadasEl presente informe que cubre América Central y el Caribe, fue realizado por el International Centre for Training and Exchanges in Geosciences (CIFEG), bajo la dirección del Profesor Robert D'Ercole (Université de Savoie).Thierry Lesales (Université des Antilles et de la Guyane) participó de cerca a la realización de este documento y estuvo activamente implicado junto al Profesor D'Ercole en las misiones que se realizaron en varios países. En el curso de estas misiones, se entrevistaron con numerosos representantes de gobiernos nacionales, de ONGs y de organizaciones regionales e internacionales Se contó igualmente con la asistencia de Claudine Misson (CRED), quien realizó la misión en República Dominicana. El informe se basa igualmente en una misión anterior llevada a cabo por Philippe Masure (BRGM, France), Alexandra Angulo (CRED) y Christian Bugnion (CRED), la cual realizó parte del trabajo preparatorio para el diagnóstico.El informe presenta un análisis de la situación en América Central y el Caribe y provee recomendaciones preliminares para las prioridades y dirección del futuro programa. En el marco de la segunda fase, está destinado a servir de base para la formulación del Plan de Acción de Preparación a los Desastres de ECHO.
Depuis 1994, ECHO (Office Humanitaire de la Commission Européenne, devenu le service de la Commission européenne à l’aide humanitaire et à la protection civile) a financé, à l'échelle mondiale, de nombreuses opérations pour la prévention et la préparation aux catastrophes (catastrophes naturelles principalement) Ces financements ont répondu aux demandes d'ONG et d'organisations internationales qui ont-elles-mêmes mis en oeuvre les projets correspondants. Les évaluations de ces opérations ont donné des appréciations positives. Cependant, ECHO souhaite s'impliquer davantage dans la prévention et la préparation aux catastrophes et mieux cibler ses actions pour une plus grande cohérence d'ensemble.Au cours de la réunion du 16 juillet 1996, le Comité d'Aide Humanitaire a approuvé la nouvelle approche régionale proposée par ECHO pour son programme de prévention, d'atténuation et de préparation aux catastrophes, le DIPECHO (Dlsaster Preparedness ECHO), pour la période 1996—1998. Ce programme doit s'appliquer dans un cadre régional en concentrant d'abord ses financements sur des plans d'action dans les Caraïbes, en Amérique Centrale, en Asie du Sud-Est et au Bangladesh. Par ailleurs, au lieu de répondre exclusivement aux demandes de financements spécifiques d'ONG, d'organisations internationales et de gouvernements, ECHO souhaite préparer des plans d'action et déterminer les partenaires les plus appropriés pour une mise en oeuvre dirigée par ECHO même. En outre, le DIPECHO a pour objet de rendre plus efficace l'action de l'ensemble de l'Union Européenne, par une étroite coordination de son action avec celles de la Commission et des Etats Membres. Il est enfin prévu de faire précéder la préparation des plans d'action par une phase de diagnostic au cours de laquelle seront identifiés, pour chaque région, les risques, les structures et politiques de prévention existantes aux niveaux communautaire, national et régional, ainsi que les appuis extérieurs en cours et à venir. L'objectif est non seulement de déterminer les lacunes, mais également d'évaluer la cohérence et l'efficacité des systèmes de réponse dans leur ensemble......Dans ce contexte, une première mission exploratoire a été réalisée du 30 septembre au 12 octobre 1996 dans les Caraïbes et l'Amérique Centrale (quatre pays visités) et a débouché sur un premier rapport (A. Angulo, Ch. Bugnion, Ph. Masure, "Rapport de mission exploratoire dans les Caraïbes ct en Amérique Centrale pour DIPECHO").Ce rapport apporte de nombreuses informations et en particulier:(1) il définit le cadre conceptuel, insistant, à juste titre, sur le fait que la prévention et la préparation doivent être distinguées de l'aide d'urgence et qu'elles font partie d'un processus continu au même titre que le développement ;(2) il présente les principales organisations régionales et internationales, et leurs activités dans le domaine de la prévention et de la préparation;(3) il met en évidence les grands types de besoins et fournit les premières orientations pour le programme DIPECHO......Le présent rapport, constituant le diagnostic proprement dit, fait suite à une deuxième série de missions effectuées dans la même région. Il vise à compléter les apports de la mission exploratoire, notamment par:(a) une analyse des catastrophes et de leurs conséquences:(b) une évaluation comparée des risques dans la région;(c) une analyse détaillée des réalisations et des besoins en matière de réduction des risques et des conséquences des catastrophes naturelles ;(d) un examen des conditions actuelles pour un programme DIPECHO cohérent, réalisable et efficace, avec, en particulier, la prise en compte de l’organisation actuelle de la prévention et de la préparation dans la région et un état des appuis extérieurs ;- des propositions de lignes d'actions prioritaires pour le DIPECHO......Le diagnostic s'est appuyé sur une importante documentation : travaux scientifiques, études et rapports recueillis auprès du CRED-Université Catholique de Louvain, du CIFEG, du DHA, de l’IDNDR, de divers organismes sur le terrain (notamment le centre de documentation de San José au Costa Rica), et d'universités européennes (Université de Savoie. Chambéry, Université de Lausanne). Mais ce sont avant tout les nombreux entretiens menés lors des missions (près de 200) qui ont donné corps au diagnostic.Treize pays Ont été visités entre le 22/01 et le 07/03/1997 :- République Dominicaine (C Misson);- Costa Rica, Guatemala, Nicaragua et Cuba (R. D'Ercole) ;- Antigua, Barbade, Haïti, Jamaïque, Ste-Lucie, St-Maarten, St-Vincent et le Guyana (Th. Lesales).Leur choix a été déterminé en concertation avec ECHO, le CRED-UCL et le CIFEG. Ils ne recouvrent pas l'ensemble des pays qu'il aurait été théoriquement possible de visiter. Cependant, le choix de pays-clés, les contacts établis avec de nombreux organismes de portée régionale et la documentation consultée, ont permis de bâtir un diagnostic d'ensemble......L'étude comporte trois parties.La 1e partie constitue une analyse des catastrophes en termes de bilan et de risque. Il s'agit, à l'aide de cartes, notamment, de montrer les effets des catastrophes naturelles en Amérique Centrale et dans les Caraïbes, de présenter la répartition et la fréquence des aléas naturels et de procéder à une analyse de critères de vulnérabilité. L'objectif est, enfin, de déterminer des niveaux de risque, à l'échelle de la région, compte tenu des dangers naturels et des critères de vulnérabilité.La 2° partie est l'étude des actions entreprises dans la région, ces dernières années, afin de réduire les risques et les conséquences des catastrophes. Cette étude permet de dégager des lacunes et des besoins. Les différentes composantes entrant dans le processus de réduction des catastrophes sont retenues : recherche scientifique et technique, prévention stricto sensu, préparation, information / formation. L'accent est également placé sur les modes actuels d'application des politiques de réduction des risques : de l'approche sectorielle à l'approche intégrée.La 3e partie traite des conditions actuelles pour la mise en oeuvre d'un programme DIPECHO cohérent et efficace. Quatre aspects fondamentaux sont analysés: les particularités régionales et nationales (l'hétérogénéité et ses conséquences); les faiblesses et qualités institutionnelles aux différents échelons géographiques: les caractéristiques des organismes susceptibles de contribuer à la mise en oeuvre du DIPECHO; le rôle actuel et en perspective de la Communauté Européenne et des Etats Membres.Chaque partie comporte une conclusion partielle La conclusion générale reprend les idées force des conclusions intermédiaires ct débouche sur des lignes d'actions prioritaires recommandées pour le DIPECHO......L'étude confiée au CIFEG par le CRED-UCL et ECHO a été coordonnée par Robert D'Ercole (Département de Géographie, Université de Savoie, Chambéry, France). Elle a bénéficié de la collaboration de Thierry Lesales (Département de Géographie, Université des Antilles et de la Guyane, Martinique, France) et de Patrick Pigeon (Département de Géographie, Université de Savoie, Chambéry, France). Ont également contribué à la réalisation de celle étude: Claudine Misson (CRED-UCL, Belgique), Jean-Claude Napias (CIFEG, directeur), Jacques Giri (CIFEG, président), Sylvie Orlyk (CIFEG, secrétariat).
https://hal.archives-ouvertes.fr/hal-01196496

hal-01196496
https://hal.archives-ouvertes.fr/hal-01196496
https://hal.archives-ouvertes.fr/hal-01196496/document
https://hal.archives-ouvertes.fr/hal-01196496/file/D%27Ercole%20et%20al%201997%20Diagnostic%20DIPECHO%20Caraibes%20compressed.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Karukéra spur is an easternmost submerged rise of the Lesser Antilles fore-arc in the Guadeloupe archipelago, culminating about 4000 m above the fore-arc basin 150 km west of the deformation front. The analysis of 3500 km 2D high-resolution multichannel seismic reflection and multibeam bathymetric data, and the study of 14 core samples, allow for the first time to reconstruct its sedimentary anatomy and tectonic evolution. Seven seismic units (US1 to US7) are evidenced, organised into four major depositional sequences separated by erosional surfaces. Units US1 to US4 thicken to the south-southeast on the spur. The sedimentary deposits rest upon a deeply eroded metamorphic basement of the Caribbean Plate as in La Désirade Island. Sequence 1 (units US1 and US2) remains unknown in its lower part because it does not outcrop. Its upper part comprises early Miocene shallow water carbonates. Sequence S2 (Unit US3) only comprises an upper Miocene transgressive systems tract deposited into basinal environment. It is bounded by major erosional surfaces SB2 and SB3. Sequence 3 (US4 to US6) is Zanclean to Pleistocene. It is dominantly composed of shallow water, reefal deposits. Sequence 4 corresponds to recent deposits. The Karukéra spur experienced three main extensional episodes with alternations between uplift and subsidence periods. Uplifts are responsible for emersions and erosions. Subsidence severely drowned shallow water deposits. The first extensional episode led to the formation of horsts and grabens in the basement, prior to early Miocene deposits. The second extensional episode occurred during upper Miocene, in accordance with data in surrounding islands. The third tectonic episode developed since Calabrian. Noticeable is the constant reactivation of N130°–N150°, N150°–N180° and N40° trending faults since early Miocene and the neoformation of E–W trending faults since Calabrian. Our results suggest that at the latitude of Guadeloupean archipelago the Lesser Antilles subduction zone is an erosional margin because of the successive sweepings of the Santa Lucia then Tiburon Ridges.
ISSN: 0025-3227

hal-01172231
https://hal.archives-ouvertes.fr/hal-01172231
DOI : 10.1016/j.margeo.2015.02.007

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Mediterranean geodynamic system is an exceptional natural laboratory to study the complexities of back-arc extension during subduction rollback. Corsica is a key locality that recorded the Alpine subduction-collision history followed by 30 Ma of the Apennines slab rollback, responsible for the successive opening, from West to East, of the Liguro-Provençal basin and the Tyrrhenian Sea. The overall strain pattern of the Alpine metamorphic units of Alpine Corsica is studied through a synthesis of i) available geological maps, ii) geochronological data and iii) newly acquired structural data relative to successive events of ductile and brittle extension, Three main stages of extension are recorded: 1/ Syn-metamorphic Oligocene extension accommodated by N140° trending ductile shear zones, that correspond to the reactivation of a major Alpine thrust; 2/ Burdigalian ramp-flat extension with N60°-70° trending fault zones that controlled the deposition of onshore piggy-back basins (e.g. St Florent basin), and 3/ Serravalian N-S trending fault zones. From a geodynamical point of view, these successive extensional deformations in Alpine Corsica can be correlated to the history of the Apennines slab rollback. The two first stages are related to a southeastward rollback of the Appennines slab that successively triggered: 1/ Continental rifting in Oligocene leading to the opening of the Liguro-Provençal basin and 2/ Burdigalian extension with N60°-70° trending fault zone, oblique to the Alpine thrust that, after a counterclockwise rotation of the Corso-Sardinian block, became unable to accommodate extension. Finally, the third stage that gave NS-trending fault zones developed in Serravalian, at the onset of Tyrrhenian rifting, related to an eastward rollback of the Apennines slab, as a response of slab tearing in Sicily.
ISSN: 0040-1951

insu-01424859
https://hal-insu.archives-ouvertes.fr/insu-01424859
https://hal-insu.archives-ouvertes.fr/insu-01424859/document
https://hal-insu.archives-ouvertes.fr/insu-01424859/file/gueydan-tectonoph-2017.pdf
DOI : 10.1016/j.tecto.2016.12.028

Éditeur(s) : HAL CCSD
Résumé : International audience
Background: Comparative analysis, which aims at investigating ecological and evolutionary patterns among species, may help at targeting reservoirs of zoonotic diseases particularly in countries presenting high biodiversity. Here, we developed a simple method to target rodent reservoirs using published studies screening microparasite infections. Methods: We compiled surveys of microparasites investigated in rodents trapped in Thailand. The data comprise a total of 17,358 rodents from 18 species that have been investigated for a total of 10 microparasites (viruses, bacteria and protozoans). We used residual variation of microparasite richness controlled for both rodent sample size and pathogens' screening effort to identify major rodent reservoirs and potential risky habitats. Results: Microparasite species richness was positively related to rodent sample size and pathogens' screening effort. The investigation of the residual variations of microparasite species richness showed that several rodent species harboured more pathogens than expected by the regression model. Similarly, higher pathogen richness than expected was observed in rodents living in non-flooded lands, forests and paddy fields. Conclusion: Our results suggest to target some rodent species that are not commonly investigated for pathogen screening or surveillance such as R. andamanensis or B. savilei, and that non-flooded lands and forests should be more taken into caution, whereas much surveys focused on paddy rice fields and households.
Infection Ecology and Epidemiology

ird-00714369
http://hal.ird.fr/ird-00714369
http://hal.ird.fr/ird-00714369v2/document
DOI : 10.3402/iee.v2iO.18637
IRD : fdi:010055557