Éditeur(s) : AMC : Association Mélanges Caraïbes
Extrait de : "Albert Camus, Aimé Césaire : poétiques de la révolte" : colloque, du 13 au 15 novembre 2013. Université des Antilles et de la Guyane
Description : Marie Rose Abomo-Maurin s'interroge sur la façon dont les deux dramaturges rendent compte du sort et de la révolte des personnages et ce qui détermine chez eux le tragique. Pour répondre à cette problématique, elle s'intéresse d'abord à la construction des personnages principaux. Dans un second temps, elle se penche sur les caractéristiques de l'écriture de la tragédie et de la révolte. Elle s'arrête pour finir sur la mise en évidence du combat de l'absurde, compressible de la consécration de la tragédie moderne.
Siècle(s) traité(s) : 21
Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V14015
V14015

Éditeur(s) : Gauthier-villars
Résumé : The new bathymetric, magnetic and mainly seismic data acquired during the Zoesis cruise, reveal the presence of compressional features in the ''Fairway Ridge-Fairway Basin-Lord Howe Rise (northern part)'' area, west of New Caledonia. The compressive strain is especially responsible for the formation of the Fairway Ridge. The compression is emphasized by a regional unconformity that could be dated late Eocene, according to DSDP data in the area, and therefore synchronous with the late Eocene obduction of the New Caledonia ophiolites. The westward extension of the late Eocene compressive strain in the New Caledonia area is more developed than previously thought.
De nouvelles données bathymétriques, magnétiques et principalement de sismique réflexion, recueillies durant la campagne Zoesis, révèlent l'existence de figures compressives à l'ouest de la Nouvelle-Calédonie, a travers l'ensemble <( ride de Fairway - bassin de Fairway - partie nord de la ride de Lord Howe D. La tectonique compressive, en particulier responsable de la formation de la ride de Fairway, est soulignée par une discordance régionale qui, compte tenu des données de forages DSDP sur la région, serait d'âge Eocene supérieur et donc synchrone du charriage de la nappe ophiolitique sur le bâti Calédon&. Les effets de I'épisode compressif fini-éocène qui affecte la Nouvelle-Calédonie sont ressentis bien plus à l'Ouest que précédemment supposé.
Comptes Rendus de l'Academie des Sciences Serie II (1251-8069) (Gauthier-villars), 1994-11 , Vol. 319 , N. 9 , P. 1063-1069

Droits : Académie des Sciences
http://archimer.ifremer.fr/doc/00183/29457/27888.pdf
http://archimer.ifremer.fr/doc/00183/29457/

Éditeur(s) : Taylor & Francis Ltd
Résumé : A new benthic phototrophic dinoflagellate is described from sediments of a tropical marine cove at Martinique Island and its micromorphology is studied by means of light and electron microscopy. The cell contains small golden-brown chloroplasts and the oval nucleus is posterior. It is laterally compressed, almost circular in shape when viewed laterally. It consists of a small epitheca tilted toward the right lateral side and a larger hypotheca. In the left view, the cingulum is more anterior and the epitheca is reduced. The cingulum is displaced and left-handed. This organism is peculiar in having no apical pore and its thecal plate arrangement is 2 ' 1a 7 '' 5c 3s 5 ''' 1 ''''. The plates are smooth with small groups of pores scattered on their surface. An area with 60-80 densely arranged pores is found near the centre of the 2 ''' plate, on the left lateral side. Morphologically, these features are different from all other laterally compressed benthic genera. In addition, molecular genetic sequences of SSU and partial LSU form a distinct and well-supported clade among dinoflagellates and support the erection of a new genus. However, molecular phylogenies inferred from ribosomal genes failed to confirm any clear relationship with other benthic taxa and affinity with other laterally compressed dinoflagellates has not been demonstrated. Hence, the taxonomic affinity of Madanidinium loirii with a defined order and family is unclear at the moment.
European Journal Of Phycology (0967-0262) (Taylor & Francis Ltd), 2014-04 , Vol. 49 , N. 2 , P. 165-178

Droits : 2014 British Phycological Society
http://archimer.ifremer.fr/doc/00195/30622/29458.pdf
DOI:10.1080/09670262.2014.898797
http://archimer.ifremer.fr/doc/00195/30622/

Résumé : Planta herbácea erguida de hasta 1.7 m de alto, glabra y glauca. Hojas alternas, oblongas a obovadas de hasta 35 cm, tripinnadas con los últimos segmentos filiformes; vainas peciolares de 1-3 cm de longitud. Inflorescencias con umbelas terminales y laterales; flores numerosas de pétalos amarillos. Fruto ovado-elíptico, glabro, de hasta 4 mm de longitud, compreso dorsalmente, costillas estrechamente aladas, las 2 laterales más amplias. Con frecuencia esta especie es confundida con Foeniculum vulgare, el cual tiene una vaina peciolar más larga y todas las costillas del fruto son iguales.
Plante herbacée, à tige dressée, pouvant atteindre 1,7 m de haut. Feuilles oblongues à ovées, tripennées de 20-40 sur 10-20 cm, les derniers segments sont filiformes. Ombelles de 15 cm de diamètre, nombreuses fleurs, pétales jaunes. Fruit ovalo-elliptique de 4 mm sur 2 mm. Cette espèce est fréquemment confondue avec Foeniculum vulgare, laquelle a une gousse pétiolaire plus large et toutes les côtes de fruit égales.
Erect herb, up to 1.7 m high, glabrous and glaucous.  Leaves alternate, oblong to obovate, up to 35 cm long, tri-pinnate, with filiform final segments; petiolar sheaths, 1-3 cm long; inflorescences with terminal and lateral umbels; numerous flowers bearing yellow petals; fruit ovate-elliptic and glabrous, up to 4 mm long, dorsally compressed, with tightly winged ribs, the two side ribs being broader. This species is frequently confused with Foeniculum vulgare, in spite of the fact that the latter has a longer petiolar sheath and all of its fruit ribs are all the same size.
Originaria del Mediterráneo, cultivada ampliamente en el nuevo mundo.
Originaire du bassin méditerranéen, amplement cultivée en Amérique.
Native to the Mediterranean, widely cultivated in the New World. 

http://www.tramil.net/fototeca/plant105

Éditeur(s) : HAL CCSD Société Géologique de France
Résumé : International audience
The seaward extension of onshore formations and structures were previously almost unknown in Provence. The interpretation of 2D high-resolution marine seismic profiles together with the integration of sea-bottom rock samples provides new insights into the stratigraphic, structural and paleogeographic framework of pre-Messinian Salinity Crisis (MSC) deposits of the Provence continental shelf. Seven post-Jurassic seismic units have been identified on seismic profiles, mapped throughout the offshore Provence area and correlated with the onshore series. The studied marine surface and sub-surface database provided new insights into the mid and late Cretaceous paleogeography and structural framework as well as into the syn-and post-rift deformation in Provence. Thick (up to 2000 m) Aptian-Albian series whose deposition is controlled by E-W-trending faults are evidenced offshore. The occurrence and location of the Upper Cretaceous South-Provence basin is confirmed by the thick (up to 1500 m) basinal series downlaping the Aptian-Albian unit. This basin was fed in terrigenous sediments by a southern massif (" Massif Méridional ") whose present-day relict is the Paleozoic basement and its sedimentary cover from the Sicié imbricate. In the bay of Marseille, thick syn-rift (Rupelian to Aquitanian) deposition occurred (>1000 m). During the rifting phase, syn-sedimentary deformations consist of dominant N040 to N060 sub-vertical faults with a normal component and N050 drag-synclines and anticlines. The syn-rift and early post-rift units (Rupelian to early Burdigalian) are deformed and form a set of E-W-trending en echelon folds that may result from sinistral strike-slip reactivation of N040 to N060 normal faults during a N-S com-pressive phase of early-to-mid Burdigalian age (18-20 Ma). Finally, minor fault reactivation and local folding affect post-rift deposits within a N160-trending corridor localized south of La Couronne, and could result from a later, post-Burdigalian and pre-Pliocene compressive phase.
Cadre tectonostratigraphique des formations anté-pliocènes du plateau continental de Provence (golfe du Lion oriental, SE France) Mots-clés. – Géologie marine, Tectonostratigraphie, Stratigraphie sismique, Paléogéographie crétacée, Rifting oligo-miocène, Compression post-rift Résumé. – Le prolongement en mer des formations et des structures provençales était jusqu'alors largement inconnu.L'interprétation de profils de sismique-réflexion marine 2D et l'intégration de dragages et carottages du fond-marin ont permis d'apporter des éléments nouveaux concernant le cadre stratigraphique, structural et paléogéographique des dé-pôts anté-Messiniens du plateau continental de Provence. Sept unités sismiques post-jurassiques ont été identifiées sur les profils sismiques, cartographiées à travers le plateau continental et corrélées avec les séries affleurant à terre. Une épaisse unité apto-albienne (jusqu'à 2000 m) dont le dépôt est contrôlé par des failles E-W a été mise en évidence en mer. L'existence d'un bassin subsident au Crétacé supérieur sur le plateau continental de Provence a été confirmée par le développement d'une épaisse série de bassin (jusqu'à 1500 m) reposant en downlap sur l'Apto-Albien. Le socle mé-tamorphique de l'écaille de Sicié et sa couverture sédimentaire peut être considéré comme une relique allochtone du « Massif Méridional » ayant alimenté le Bassin sud-provençal en éléments terrigènes au Crétacé supérieur. Dans la rade de Marseille, une épaisse unité syn-rift (Rupélien à Aquitanien) a été mise en évidence (>1000 m), structurée en une série de synformes en échelon d'axe E-W et affectée par des failles d'orientation dominante N040 à N060. Sur le flanc sud des synformes, la formation de plis d'axe N050 est associée à une déformation syn-sédimentaire. La formation des synformes en échelon d'axe E-W résulterait d'une réactivation en décrochement des failles N040 à N060 pendant une phase de compression N-S dont l'âge est compris entre le Burdigalien inférieur et moyen (18-20 Ma). Enfin, les dépôts post-rift sont affectés par des déformations mineures (réactivation de failles et plis associés), le long d'un couloir d'orientation N160 à l'ouest de la baie de Marseille, attribuables à une phase de compression post-burdigalienne et anté-pliocène.
ISSN: 0037-9409

hal-01463727
https://hal-amu.archives-ouvertes.fr/hal-01463727
https://hal-amu.archives-ouvertes.fr/hal-01463727/document
https://hal-amu.archives-ouvertes.fr/hal-01463727/file/Fournier_et_al_Provence_2016.pdf
DOI : 10.2113/gssgfbull.187.4-5.187

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : International audience
1] Recent statistical analysis by Lallemand et al. (2008) of subduction zone parameters revealed that the back-arc deformation mode depends on the combination between the subducting (nu(sub)) and upper (nu(up)) plate velocities. No significant strain is recorded in the arc area if plate kinematics verifies nu(up) = 0.5 vsub - 2.3 (cm/a) in the HS3 reference frame. Arc spreading ( shortening) occurs if nu(up) is greater ( lower) than the preceding relationship. We test this statistical law with numerical models of subduction, by applying constant plate velocities far away from the subduction zone. The subducting lithosphere is free to deform at all depths. We quantify the force applied on the two converging plates to sustain constant surface velocities. The simulated rheology combined viscous (non-Newtonian) and brittle behaviors, and depends on water content. The influence of subduction rate vs is first studied for a fixed upper plate. After 950 km of convergence ( steady state slab pull), the transition from extensional to compressive stresses in the upper plate occurs for vs similar to 1.4 cm/a. The effect of upper plate velocity is then tested at constant subduction rate. Upper plate retreat ( advance) with respect to the trench increases extension ( compression) in the arc lithosphere and increases ( decreases) the subducting plate dip. Our modeling confirms the statistical kinematic relationship between vsub and nu(up) that describes the transition from extensional to compressive stresses in the arc lithosphere, even if the modeled law is shifted toward higher rates of upper plate retreat, using our set of physical parameters ( e. g., 100 km thick subducting oceanic plate) and short- term simulations. Our results make valid the choice of the HS3 reference frame for assessing plate velocity influence on arc tectonic regime. The subduction model suggests that friction along the interplate contact and the mantle Stokes reaction could be the two main forces competing against slab pull for upper mantle subductions. Besides, our simulations show that the arc deformation mode is strongly time dependent.
ISSN: 1525-2027

hal-00412328
https://hal.archives-ouvertes.fr/hal-00412328
https://hal.archives-ouvertes.fr/hal-00412328/document
https://hal.archives-ouvertes.fr/hal-00412328/file/arcayG32008.pdf
DOI : 10.1029/2007GC001875

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We use first first-principle methods and the Peierls-Nabarro model to evaluate the resistance to glide, characterized by the Peierls stress, of glide systems for end-member MgSiO3 Perovskite at mantle pressures. [010](100) is the easiest glide system in Mg-Perovskite at all pressures. Peierls stresses increase systematically with pressure for all systems except [001](010), indicating the importance of lattice friction at lower mantle pressures. The ratio of the maximum Peierls stress for each system relative to the [010](100) value defines their critical resolved shear stress (CRSS). These CRSS are used in a visco-plastic self-consistent homogenization model to predict the evolution of crystal preferred orientations (CPO) during deformation of polycrystalline Mg-Perovskite. In axial compression, [100] tends to align with the compression direction, in agreement with in situ observations in axial compression experiments. In simple shear, [010] concentrates near the shear direction and (100), although more dispersed, tends to align near the shear plane, consistent with the dominant activity of the easier [010](100) system. The calculated seismic anisotropy for a 100% Mg-Perovskite aggregate using the CPO in simple shear and the elastic constants Of MgSiO3 perovskite at lower mantle pressures and temperatures is weak (>3% for P-waves with and >2% for S-waves) and decreases with increasing temperature and pressure. P-waves show the fastest propagation parallel to the lineation and S-waves fast polarization is in the foliation at 38 GPa and normal to the lineation at 88 GPa. This weak anisotropy is consistent with global seismological observations of a nearly isotropic lower mantle. There are however two regions where strain-induced Mg-Perovskite CPO could contribute to anisotropy; a) low temperature regions in the uppermost lower mantle, where the predicted S-wave polarization anisotropy may attain 1.6% with a fast polarization parallel to the foliation, b) in high high-temperature domains in the D '' layer, where Mg-Perovskite may be the major stable phase, leading to polarization of fast S-waves normal to the lineation for propagation directions at high angle to the lineation and an apparent isotropy for all other propagation directions.
ISSN: 0012-821X

hal-00411460
https://hal.archives-ouvertes.fr/hal-00411460
DOI : 10.1016/j.epsl.2008.03.058

Résumé : Hierba erecta o postrada, anual o de corta vida. Hojas opuestas, simples de casi 7 cm de largo elípticas a lanceoladas, mucronadas en el ápice. Inflorescencias terminales a veces axilares; cabezuelas pequeñas, 3-9 mm transversalmente, radiadas, brácteas involucrales 8-9, imbricadas; flores blancas. Aquenio dorsiventralmente compreso y exactamente angulado, ligeramente alado.
Herbe dressée ou rampante, annuelle ou à vie courte. Feuilles opposées, simples, de presque 7 cm de longueur, elliptiques à lancéolées, effilées à la pointe. Inflorescences terminales parfois axillaires; petits capitules de 3-9 mm, transversalement disposés en rayons, bractées involucrées 8-9, imbriquées; fleurs blanches. Akène dont la surface supérieure et inférieure est compressée, formant des angles très nets, légèrement ailé.
Annual herb ranging from erect to creeping habit.  Leaves opposite, rough on both surfaces, sessile, elliptic-lanceolate, 8 cm x 2 cm, margin serrulate. Inflorescences axillary on long stalks; flower-heads 1 cm across, florets white; achenes black, wrinkled, without pappus appendages.
Aparentemente nativa del nuevo mundo, actualmente se distribuye ampliamente en los campos de cultivo de ambos hemisferios.  
Apparemment originaire du Nouveau Monde, actuellement largement répartie dans les champs de culture des deux hémisphères

http://www.tramil.net/fototeca/plant161

Résumé : Herbácea perenne, con ramas rastreras o ascendentes, con raíces en los nudos. Hojas opuestas, sésiles, elípticas a obovadas de 2 a 12 cm, obtusas a agudas en el ápice, más o menos cuneadas en la base, serrado-dentadas, a menudo lobuladas. Cabezuelas solitarias en pedúnculos axilares o terminales; involucros campanulados; capítulos radiados, amarillos, en número de 10 aproximadamente. Aquenio obovoide, tuberculado.
Herbacée pérenne, à branches rampantes ou ascendantes, avec des racines au niveau des noeuds. Feuilles opposées, sessiles, elliptiques à obovées de 2 à 12 cm, obtuses à aiguës à la pointe, plus ou moins cunéiformes à la base, aux bords découpés en dents-de-scie, souvent lobées. Capitules solitaires en pédoncules axillaires ou terminaux; involucrés en forme de clochette; capitules radiés, jaunes, approximativement au nombre de 10. Akène ovoïde, tuberculé.
Perennial herb, with trailing or ascending branches rooting at thenodes.  Leaves opposite, sessile, elliptical to obovate, 2-12 cm x 1-6 cm, apex acute,cuneate at the base, marginsserrate-dentate often lobed; inflorescence a capitulum on axillary or terminal peduncles; ray florets bright yellow; achenes 5mm long, oblong to obovoid, compressed.
Originaria de América, ampliamente distribuida en las regiones tropicales y subtropicales del mundo.
Originaire d’;Amérique, largement répandue dans les régions tropicales et subtropicales du monde.
Native to America, widely distributed in trop

http://www.tramil.net/fototeca/plant360

Résumé : Herbácea de hasta 2 m de altura, finamente estrigulosa. Hojas alternas, pinnadas, arregladas espiralmente; folíolos en 3 a 6 pares, ovados a lanceolados, agudos a acuminados; pecíolo con glándula en la base, sésil, globosa o cónica; estípulas linear-lanceoladas a triangular, acuminadas, caducas. Racimos axilares con flores amarillas; sépalos oblongos, obtusos; pétalos ovados o elípticos. Vaina linear, obtusa, mucronata, erecta, más o menos arqueada, con numerosas semillas ovoides.
Herbacée pouvant atteindre 2 m de haut, en forme de mince quenouille. Feuilles alternes, pennées, disposées en spirales; folioles formant 3 à 6 paires, ovés à lanceolés, aigus à acuminés; pétiole avec une glande à la base, sessile, arrondie ou conique; stipules linéaire-lanceolées à triangulaires, acuminées, caduques. Grappes axillaires avec fleurs jaunes; sépales oblongs, obtus; pétales ovés ou elliptiques. Gousse linéaire, obtuse, mucronée, dressée, plus ou moins arquée, avec de nombreuses graines ovoïdes.
Erect shrubby herb, up to 2 m high.  Leaves alternate, pinnately compound with 4-5 pairs of ovate to lanceolate leaflets, 10 cm long with a narrow red margin;  inflorescence, axillary racemes, few-flowered, sepals pinkish, petals yellow 10-14 mm long, subtended by bracts 10-15 mm long; pod linear, 5-12 cm x 6-8 mm, compressed, slightly curved; seeds broadly ovoid, punctate, dark olive colour, ca. 4 mm long.
Pantropical y subtropical.
Pantropicale et subtropicale.
Pantropical and subtropical.

http://www.tramil.net/fototeca/plant318

Résumé : Planta herbácea, arrosetada, de hasta 20 cm de longitud, a menudo formando grupos. Hojas, alternas, sésiles, densamente imbricadas, linear-lanceoladas, acuminadas, verdes en ambas superficies o purpúreas en el envés. Pedúnculos, a menudo ramificados arriba; brácteas cimbiformes, ovadas, opuestas, glabras y agudas; inflorescencia incluida en la bráctea; sépalos ovado-lanceolados; pétalos ovados, blancos. Cápsula ovoidea.
Plante herbacée, feuilles basilaires disposées en couronnes serrées, pouvant atteindre 20 cm de longueur, souvent en groupes. Feuilles alternes, sessiles, densément imbriquées, linéaires-lancéolées, acuminées, vertes sur les deux faces ou avec le dessous pourpre. Pédoncules à la partie supérieure souvent ramifiée; bractées naviculaires, ovées, opposées, glabres et aiguës; inflorescence incluse sur la bractée; sépales ovo-lancéolés; pétales ovés, blancs. Capsule ovoïde.
Herb 40-70 cm high, forming large colonies, stems thick and covered with withered leaves. Leaves alternate, sessile, densely imbricate, linear-lanceolate, 20-35 x 3-5 cm, dark green above, purple beneath and along the margins; inflorescence axillary,  umbelliform cyme enclosed by compressed spathe-like bracts, 3-4.5 cm broad and 2-3 high, petals white 5-8 mm long; capsule 3-angled 4.5 mm long.
México, Guatemala, Belice y las Antillas.
Mexique, Guatemala, Belize et Antilles.
Mexico, Guatemala, Belice and the Antilles.

http://www.tramil.net/fototeca/plant351

Résumé : Arbusto o arbolito de hasta 12 m, ramas armadas con espinas rectas. Hojas pecioladas, compuestas, glabras; 1 a 3 pares de pinas; con folíolos de 12 a 20 pares por pinna, sésiles, linear-oblongos. Flores verde-amarillentas, sésiles, en espigas cilíndricas, densas, de 5 a 10 cm de longitud, pedunculadas. Vaina comprimida, falcada, coriácea indehiscente; semillas aplanadas, ovales de color café.
Arbuste ou petit arbre pouvant atteindre 12 m, branches armées d&rsquo;épines droites. Feuilles pétiolées glabres, bipennées ou tripennées, dont chaque élément porte 12 à 20 paires de folioles, sessiles, linéaires-oblongues.Fleurs vert-jaunâtres, sessiles, en épis cylindriques, denses, de 5 à 10 cm de longueur, pédonculées. Gousse comprimée, en forme de lame de faucille, coriace indéhiscente; graines plates, ovales, couleur café.
Shrub or small tree, up to 12 m high with spreading branches armed with straight spines 0.6-2.5 cm.  Leaves, petiolate 1-4 cm, bipinnate with glands between pairs of pinnae, pinnae 1 pair rarely 2, leaflets 12-20 pairs linear-oblong, 7-16 x 1.5-3.2 mm, apex obtuse or short abrupt point; inflorescence axillary in spikelike racemes, 5-10 cm long; flowers densely packed with pale yellow corolla 2.5 mm long; pod compressed, 7-20 cm x 1-1.6 cm, slightly curved, pale yellow; seeds brown 6 mm embedded in white sweet pulp.
Nativa de América tropical.
Originaire d’;Amérique tropicale.
Native to tropical America.

http://www.tramil.net/fototeca/plant259

Résumé : Hierba anual de hasta 2 m de altura. Tallo áspero o rugoso. Hojas anchamente ovadas o suborbiculares de 3 a 5 lóbulos, con la base más o menos cordada, de 8 a 18 cm de largo y dentadas. Cabezuelas masculinas en el ápice de las ramas y en las axilas de las hojas; cabezuelas femeninas una o pocas en la base de las inflorescencias, con brácteas ganchudas. Fruto capsular, ovoide y espinoso; espinas rectas y ganchudas en el ápice.
Herbe annuelle pouvant atteindre 2 m de haut. Tige âpre ou rugueuse. Feuilles largement ovées ou suborbiculaires de 3 à 5 lobes, à base plus ou moins cordée, de 8 à 18 cm de long, dentées. Capitules mâles à la pointe des branches et à l&rsquo;axe des feuilles; capitules femelles au nombre de 1 (ou un peu plus) à la base des inflorescences, avec bractées en forme de crochets. Fruit à capsule, ovoïde et épineux; épines droites et crochues à la pointe.
Annual monoecious herb 70 cm high. Leaves alternate, 7-12 cm long including petiole, base cordate or reniform, apex acute, 3-5 lobed and dentate, blades, scabrous, with appressed golden glandular hairs, triangular- orbicular 7-12 x 6-12 cm;  inflorescence racemose; male heads globose, numerous florets, female head burrlike with hooked bracts, 2 flowers; Achene, 0.9-1.5cm linear, compressed, beaked, smooth.
Cosmopolita.
Cosmopolite.
Cosmopolitan.

http://www.tramil.net/fototeca/plant361

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Using first principle simulations we calculated the elasticity of chlorite. At a density ρ~ 2.60 g cm−3, the elastic constant tensor reveals significant elastic anisotropy: VP ~27%, VS1 ~56%, and VS2 ~43%. The shear anisotropy is exceptionally large for chlorite and enhances upon compression. Upon compression, the shear elastic constant component C44 and C55 decreases, whereas C66 shear component stiffens. The softening in C44 and C55 is reflected in shear modulus, G, and the shear wave velocity, VS. Our results on elastic anisotropy at conditions relevant to the mantle wedge indicates that a 10-20 km layer of hydrated peridotite with serpentine and chlorite could account for the observed shear polarization anisotropy and associated large delay times of 1-2 s observed in some subduction zone settings. In addition, chlorite could also explain the low VP/VS ratios that have been observed in recent high-resolution seismological studies.
ISSN: 0094-8276

hal-01053707
https://hal.archives-ouvertes.fr/hal-01053707
https://hal.archives-ouvertes.fr/hal-01053707/document
https://hal.archives-ouvertes.fr/hal-01053707/file/Mookherjee_et_al-2014-Geophysical_Research_Letters.pdf
DOI : 10.1002/2014GL059334

Éditeur(s) : Amer Geophysical Union
Résumé : The Algerian margin has originated from the opening of the Algerian basin about 25-30 Ma ago. The central margin provides evidence for large-scale normal faults of Oligo-Miocene age, whereas transcurrent tectonics characterizes the western margin. A set of NW-SE oriented dextral transform faults was active during basin opening and divided the 600 km long central margin into segments of similar to 120-150 km. The upper Miocene, Plio-Quaternary, and present-day tectonic setting is, however, compressional and supports the occurrence of a margin inversion, a process still poorly documented worldwide. We show that the central Algerian margin represents a rare example of inverted margin, where the process of subduction inception is particularly well expressed and helps understand how extensional and transtensive structures are involved in margin shortening. Using multibeam bathymetry and multichannel seismic reflection sections from the MAR-ADJA 2003 and 2005 cruises, we evidence Pliocene-Pleistocene shortening with contrasting styles along the margin between west (Khayr Al Din bank) and east (Boumerdes-Dellys margin) of Algiers. Pre-Miocene structures such as basement highs and transform faults appear to control changes of the deformation pattern along this part of the margin, resulting in different widths, geometries, and relative positions of folds and faults. Plio-Quaternary and active blind thrust faults do not reuse Oligo-Miocene normal and transform faults during inversion, but instead grow within the continental margin (as testified for instance by the 21 May 2003 M-w 6.8 Boumerdes-Zemmouri earthquake), at the foot of the continental slope and at the northern sides of basement highs interpreted as stretched continental blocks of the rifted margin. The inherited structures of the margin appear, therefore, to determine this deformation pattern and ultimately the earthquake and tsunami sizes offshore. The complex geometry of the fault system along the Algerian margin suggests a process of initiation of subduction in its central and eastern parts.
Tectonics (0278-7407) (Amer Geophysical Union), 2010-03 , Vol. 29 , N. TC2008 , P. 1-22

Droits : 2010 American Geophysical Union
http://archimer.ifremer.fr/doc/00008/11883/9286.pdf
http://archimer.ifremer.fr/doc/00008/11883/9287.pdf
DOI:10.1029/2009TC002547
http://archimer.ifremer.fr/doc/00008/11883/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We investigated the response of the crystal structure, lattice parameters, and unit-cell volume of hydrous layered silicate phlogopite at conditions relevant to subduction zone settings. We have used first principles simulation based on density functional theory to calculate the equation of state and full elastic constant tensor. Based on the generalized gradient approximation, the full single crystal elastic constant tensor with monoclinic symmetry shows significant anisotropy with the compressional elastic constants: c11 = 181 GPa, c22 = 185 GPa, c33 = 62 GPa, the shear elastic constants c44 = 14 GPa, c55 = 20 GPa, c66 = 68 Ga, and c46 = −6 GPa; the off diagonal elastic constants c12 = 48 GPa, c13 = 12 GPa, c23 = 12 GPa, c15 = −16 GPa, c25 = −5 GPa and c35 = −1 GPa at zero pressure. The elastic anisotropy of phlogopite is larger than most of the layered hydrous phases relevant in the subduction zone conditions. The shear anisotropy, AVS for phlogopite is ∼77% at zero pressure condition and although it decreases upon compression it remains relatively high compared to other hydrous phases relevant in the subduction zone settings. We also note that the shear elastic constants for phlogopite are relatively low. Phlogopite also has a high isotropic bulk VP/VS ratio ∼2.0. However, the VP/VS ratio also exhibits significant anisotropy with values as low as 1.49. Thus, phlogopite bearing metasomatized mantle could readily explain unusual VP/VS ratio as observed from seismological studies from the mantle wedge regions of the subduction zone.
ISSN: 0031-9201

hal-01115670
https://hal.archives-ouvertes.fr/hal-01115670
DOI : 10.1016/j.pepi.2014.05.004

Éditeur(s) : Elsevier Sci Ltd
Résumé : Several marine geophysical data and piston-coring surveys acquired during the last decade allow one to better understand the close dynamic interactions between the sand-rich Orinoco turbidite system and the compressional structures of the Barbados prism. These interactions have been active since Eocene time as illustrated by the study of outcrops onshore Barbados Island. Because of strong morphologic and tectonic control in the east-Caribbean active margin, the present-day Orinoco turbiditic pattern system does not exhibit a classic fan geometry. The sea-floor geometry between the slope of the front of the Barbados prism and the slope of the South-American margin induces the convergence of the turbidite channels toward the abyssal plain, at the front of the accretionary prism. Also, whereas in most passive margins the turbidite systems are organized upstream to downstream as canyon, channel-levee and lobes, here, due to the tectonic control, the sedimentary system is organized upstream to downstream as channel-levee, canyons and channelized lobes. Indeed, at the edge of the Orinoco platform, the system has multiple sources with several distributaries and downstream the channel courses are complex with frequent convergences or divergences that are emphasized by the effects of the undulating seafloor tectonic morphologies associated with active thrust tectonics and mud volcanism. On top of the accretionary prism, turbidite sediments are filling transported piggy-back basins whose timing of sedimentation vs. deformation is complex. While erosion processes are almost absent on the highly subsiding Orinoco platform and in the upper part of the turbidite system, they develop mostly between 2000 and 4000 m of water depth, above the compressional structures of the Barbados prism (canyons up to 3 km wide and 300 m deep). In the abyssal plain, the main turbiditic channel develops toward the east and connects with the Vidal mid-Atlantic channel. The sediments transported in this channel are filling several elongated basins linked with fracture zones (notably the Barracuda Basin), and finally end their course in the Puerto-Rico trench, the deepest morphologic depression of the region. Piston-cores have demonstrated that turbidite sediments above the accretionary prism and in the abyssal plain are mostly coarse sandy deposits covered by recent pelagic planktonic-rich sediments, which corresponds to slower sand deposition during the post-glacial sea level rise. Numerical stratigraphic modelling suggests that during the last glacial event, the main depocentres were located above the tectonic prism and in the abyssal plain, at the front of the prism and that, during the Holocene eustatic rise, a large accommodation space formed on the shelf confining sedimentation mostly on the Orinoco deltaic platform and producing a starvation downstream in the turbidite system.
Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2015-06 , Vol. 64 , P. 76-103

Droits : 2015 Elsevier Ltd. All rights reserved.
http://archimer.ifremer.fr/doc/00252/36373/34913.pdf
DOI:10.1016/j.marpetgeo.2014.12.015
http://archimer.ifremer.fr/doc/00252/36373/

Éditeur(s) : HAL CCSD MAIK Nauka/Interperiodica
Résumé : International audience
The paper is concerned with the kinematics of the major faults, their pattern, and the time of occurrence of compression and extension deformations in the southeast of the Eastern Sayan. The geometry of the mountain ranges and the kinematics of the major faults exhibit northeast-oriented compression responsible for the current processes of relief formation, which corresponds to the direction of the vector of deformations associated with the Indo-Asian collision. The results obtained thus far may be indicative of the remote influence of collision on the orogenic activity and transpressional deformations in the Eastern Sayan since the end of the Miocene. Morphotectonic analysis has shown that the areas of Quaternary extension- related deformations in the Eastern Sayan are not a response to active rifting in the Baikal Rift Zone. The position and geometry of the subsided blocks and magma ruptures point to the fact that they form locally as extension structural elements near the strike-slip faults. The strike-slip and thrust faults are widespread and play the leading role in the development of the southeastern part of the Eastern Sayan.
ISSN: 0016-8521

insu-00667345
https://hal-insu.archives-ouvertes.fr/insu-00667345
DOI : 10.1134/S001685211101002X

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Talc is a hydrous magnesium rich layered silicate that is widely disseminated in the Earth from the seafloor to over 100 km depth, in ultra-high pressure metamorphism of oceanic crust. In this paper we determine the single crystal elastic constants at pressures from 0 to 12 GPa of talc triclinic (C 1¯) and monoclinic (C2/c) polytypes using ab initio methods. We find that talc has an extraordinarily high elastic anisotropy at zero pressure that reduces with increasing pressure. The exceptional anisotropy is complemented by a negative Poisson's ratio for many directions in crystal space. Calculations show that talc is not only one of very few common minerals to exhibit auxetic behaviour, but the magnitude of this effect may be the largest reported so far for a mineral. The compression (Vp) and shear (Vs) wave velocity anisotropy is 80% and 85% for the triclinic polytype. At pressures where talc is known be stable in the Earth (up to 5 GPa) the Vp and Vs anisotropy is reduced to about 40% for both velocities, which is still a very high value. Vp is slow parallel to the c-axis and fast perpendicular to it. This remains unchanged with increasing pressure and is observed in both polytypes. The shear wave splitting (difference between fast and slow S-wave velocities) at low pressure has high values in the plane normal to the c-axis, with a maximum near the alow asterisk-axis in the triclinic and the b-axis in the monoclinic polytype. The c-axis is the direction of minimum splitting. The pattern of shear wave splitting does not change significantly with pressure. The volume fraction of talc varies between 11 and 41% for hydrated mantle rocks, but the lack of data on the crystallographic preferred orientation (CPO) precludes a detailed analysis of the impact of talc on seismic anisotropy in subduction zones. However, it is highly likely that CPO can easily develop in zones of deformation due to the platy habit of talc crystals. For random aggregates of talc, the isotropic Vp, Vs and Vp/Vs ratio have significantly lower values than those of antigorite and may explain low-velocity regions in the mantle wedge. Vp/Vs ratios are more complex in anisotropic media because there are fast and slow S-waves, resulting in Vp/Vs1 and Vp/Vs2 ratios for every propagation direction, making interpretation difficult in deformed polycrystalline talc with a CPO. Talc on the subduction plate boundary can strongly influence guided wave velocity as CPO would develop in this region of intense shearing. The very low coefficient of friction (< 0.1) of talc above 100 °C could also explain silent earthquakes at shallow depths (ca 30 km) along the subduction plate boundaries, frequently responsible for tsunami.
ISSN: 0012-821X

hal-00411481
https://hal.archives-ouvertes.fr/hal-00411481
DOI : 10.1016/j.epsl.2008.07.047

Éditeur(s) : HAL CCSD Geological Society of London
Résumé : International audience
In Eastern China, the North China Block (NCB) has experienced a complex tectonic evolution during Late Palaeozoic to Mesozoic times. The unconformable sedimentary cover, which ranges in age from Neoproterozoic to Permian, underwent two tectonic episodes in Early Triassic and Cretaceous times. An early north–south compressional phase, D1, characterized by north-verging recumbent folds with east–west-trending axes and top-to-the-north ductile shear zones can be observed in a gabbroic pluton and the Neoproterozoic sedimentary host rocks. The available radiometric ages allow us to interpret this event as an Early Triassic back-thrusting related to the final stage of the collision between the North China and South China Blocks. During the LateMesozoic, an extensional event characterized by (1) half-grabens filled by continental terrigeneous red beds and lava flows, (2) low-angle detachment faults, (3) synkinematic granitic plutons, and (4) metamorphic core complexes is widespread in the Eastern Liaoning Peninsula. This extensional D2 event can be subdivided into a ductile deformation and a brittle deformation, corresponding to different expressions of crustal deformation. In every area studied in the Eastern Liaoning Peninsula, the ductile D2 deformation is characterized by a NW–SE-trending stretching lineation with a top-to-the-NWsense of shear.Mica and amphibole fromthe metamorphic country rocks, granodioritic or monzogranitic plutons and their mylonitized margins yield 40Ar/39Ar ages ranging from 130 to 120 Ma. These dates support fast cooling and exhumation rates coeval with the extensional tectonics. The brittle D2 deformation is responsible for the formation of high-angle normal faults marked by low-temperature cataclasites bounding half-grabens. During the Mesozoic, the tectonic regime of Eastern China experienced a significant inversion from compression to extension. The Eastern Liaoning Peninsula massif provides an example of this geodynamic transition.
ISSN: 2041-4927

hal-00134055
https://hal-insu.archives-ouvertes.fr/hal-00134055
DOI : 10.1144/SP280.7