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At mid-oceanic ridges, mantle temperature and magma supply influence the structure of the neo-volcanic zone. Due to the large Romanche offset, a strong “cold edge” effect is present at its eastern intersection with the Mid-Atlantic Ridge. This effect decreases with the distance from the transform fault, making this region an ideal area to study the impact of the thermal gradient on the architecture of the neo-volcanic zone. We analyzed seafloor videos and photos from submersible dives, as well as bathymetry and backscatter data collected during the SMARTIES cruise (2019), from the Ridge-Transform Intersection (RTI) to approximately 80 km to the south of it. We produced maps at local and regional scales and quantified the morphology of volcanoes (height, diameter, height/diameter ratio, volume and surface). Visual observations have showed that the seafloor is mainly made up of pillows or elongated pillows and rare massive lava flows. Within 30 km of the RTI, the neo-volcanic area is characterized by clusters of volcanoes, affected by faults trending N120-130° E, oblique to the extension and to the transform fault orientation, and by faults trending E-W. At 30 km to 50 km from the RTI, the Central segment displays a robust volcanic ridge oriented N150°E built by a pilling of volcanoes and narrow ridges. Its eastern and southern parts are old and characterized by oblique faults and narrow ridges (N130-140°E), while the northwest portion is more recent, faults and ridges are almost normal to the extension. The southernmost segment, located at 80 km from the RTI, is orthogonal to the spreading direction and asymmetric, bounded at the west by a detachment fault. Recent volcanic edifices were observed from the center of the segment to the base of the detachment. Our observations suggest that the neo-volcanic area is fed by more and more magma from north to south. This increase in magma supply is marked by a more structured volcanic axis, volcanoes that are more voluminous and a change in the orientation of the segments and faults. Changes in the orientation of faults and off-axis abyssal hills also reveal variations in the magmatic supply over time.

We studied the east intersection between the Romanche transform fault (TF) and the Mid-Atlantic ridge using bathymetry and gravity anomalies, to investigate the temporal evolution of the ultra-cold ridge-transform intersection. Our results reveal a complex ridge axis, with evidence of a significant decrease in the along-axis melt supply towards the RTI but also since ~10 Ma.Over a 100 km distance south of the RTI, the ridge axis is formed by three spreading segments offset by large non-transform discontinuities. Large detachment faults mark the present-day spreading style at the RTI, while magma supply increases away from the Romanche intersection. Axial and near-axis fault patterns reveal a marked obliquity, especially in the north and center of the study area.In lithosphere older than 10 Ma, the ridge axis appears to form a single spreading segment between the Romanche and Chain TFs, perpendicular to the spreading direction, with relatively regular abyssal hills. From around 10 to 3 Ma, oceanic core complexes (OCCs) developed in the northern part of the ridge axis south of the Romanche TF. The complexity of the ridge axis appears to have increased in the last 3 Ma, with ridge obliquity accompanying axial instabilities and ridge jumps. At least three eastward ridge relocations were identified immediately south of the Romanche TF, rupturing a series of OCCs located in the African plate, east of the ridge axis. This pattern could reflect a progressive decrease in the melt supply, in particular since 3-5 Ma. This may be related to a significant reduction of the ridge spreading rate as seen from kinematic models which allowed the cooling effect of the large offset Romanche TF to dominate the spreading processes in the area.

Oceanic Transform Faults (OTFs) are major plate boundaries that regularly offset the axis of Mid-Oceanic Ridges and are able to generate Mw 7 earthquakes. Yet, very little is known on the evolution of fault slip mechanics at depth, mainly due to rare exposures of deep sections at the seafloor. The Atobá Ridge is one of the rare structures where the roots of an active transform fault are exposed and accessible. This transpressive ridge is part of the northern transform fault of the St. Paul transform system in the Equatorial Atlantic (Maia et al., 2016). There, ultramafic mylonites are tectonically exhumed along the inner thrust faults of a positive flower structure.Here we study the deformation mechanisms in ultramafic mylonites and ultramylonites sampled at the Atobá ridge. We show that all samples experienced ductile deformation at 750-900°C in the spinel stability field, resulting in a pervasive grain size reduction. We propose fluid-assisted dissolution-precipitation creep as the main deformation mechanism, leading to dissolution of orthopyroxene and formation of lens-shaped olivine and interstitial minor phases’ neoblasts (pyroxenes, spinel, and amphibole). Orthopyroxene neoblasts formed by this mechanism mimic the Crystallographic Preferred Orientation of the olivine neoblasts. Fluid-assisted dissolution-precipitation creep allows deformation of stiff minerals at significant lower stresses and temperatures than dislocation creep, possibly leading to an intense strain localization. This mechanism, previously reported in ophiolites and orogenic contexts (Hidas et al., 2016; Prigent et al., 2018), is described for the first time in the oceanic transform environment. Similar microstructures have been observed in mylonites from other OTFs, suggesting that this mechanism could be more widespread and could even represent one of the main deformation law in the lower oceanic lithosphere, with important implications on the mechanics and structures of (oceanic) transform faults and long-lived detachments.This work is supported by PRIN2017KY5ZX8.REFERENCESMaia, M., Sichel, S., Briais, A., Brunelli, D., Ligi, M., Ferreira, N., Campos, T., Mougel, B., Brehme, I., Hémond, C. and Motoki, A., 2016. Extreme mantle uplift and exhumation along a transpressive transform fault. Nature Geoscience, 9(8), pp.619-623.Hidas, K., Tommasi, A., Garrido, C. J., Padrón-Navarta, J. A., Mainprice, D., Vauchez, A., Barou, F., & Marchesi, C. (2016). Fluid-assisted strain localization in the shallow subcontinental lithospheric mantle. Lithos, 262(October), 636–650. https://doi.org/10.1016/j.lithos.2016.07.038Prigent, C., Guillot, S., Agard, P., & Ildefonse, B. (2018). Fluid-assisted deformation and strain localization in the cooling mantle wedge of a young subduction zone (Semail ophiolite). Journal of Geophysical Research: Solid Earth, 123. https://doi.org/10.1029/ 2018JB015492

The George V and Tasman Transform Fault Systems (TFS) are major, right-stepping offsets of the South-East Indian Ridge between 140°E and 148°E. The George V TFS (~140°E) has an offset of about 300 km, and the Tasman TFS (~148°E) an offset of about 600 km. These TFS have multiple shear zones with intra-transform ridge segments (ITRS), mostly unmapped yet. We present the results of the analysis of geophysical and petrological data collected during the STORM cruise (South Tasmania Ocean Ridge and Mantle), completed with global data sets including satellite-derived gravity and bathymetry, and earthquake distribution. The swath bathymetry data cover some parts of the shear zones and only a few of ITRSs. They reveal a complex interaction between tectonic processes at the plate boundary and near-axis volcanic activity along and across the transform faults. In both the George V and Tasman TFS the western ITRS are shallower than the eastern ones, and they appear to receive a lot more magma supply. These western ITRS display off-axis volcanism observed on swath bathymetry or suspected from free-air gravity anomaly highs. In both TFS also, the western shear zone consists of two segments separated by a tectonic massif which we interpret to represent a push-up resulting from transpression along the transform. The mechanism involved in generating the transpression is a lengthening of the western ITRS to the west due to its high magma supply, leading to an overlap between the ITRS and the ridge segment immediately to the west of the TFS, that is in a mechanism similar to the processes currently uplifting the mylonitic massif along the St. Paul TF in the Equatorial Atlantic. The bathymetric and backscatter maps of the western George V TFS also reveal a series of recent off-axis oblique volcanic ridges. Rocks dredged on one of these ridges consist of picrites (i.e. basalts rich in olivine phenocrysts). These observations suggest that both TFS are not magma starved like many mid-ocean ridge transforms, but are the locus of significant primitive melt supply. Such an unexpected production of high-Mg melt might be related to the presence of a mantle thermal anomaly beneath the easternmost SEIR, the result of regional extension following clockwise rotations of the spreading direction, and/or to a western flow of mantle across the TFS. Some of the ITRS actually appeared after changes in the Australia-Antarctic plate motion.

Accretionary processes at mid-ocean ridge segments with low magma input have seldom been investigated over the long term. The evolution of such magma-starved segments over time is still largely unknown. We present a study on the structure and evolution of the southernmost intra-transform ridge segment of the St. Paul Transform Fault System in the Equatorial Mid-Atlantic Ridge, based on new bathymetry, gravity, and rock sampling data. We show that this area evolves differently from previously described tectonics along ridge segments of similar spreading rate. On the flanks of the axial ridge segment, we observe a succession of structures exhumed by detachment faulting, evolving from east-facing, long-lived, corrugated oceanic core complexes (∼6 Ma ago), to short-lived detachment faults exposing lower crust and mantle rocks and facing alternatively east and west in the more recent part of the segment. The oldest detachment faults have been repeatedly split and partially transferred to the opposite flank through the formation of new detachments into the footwall. The terminations of three old, east-facing detachments are observed on the east flank of the segment. The westward relocations of the plate boundary appear to compensate for the asymmetry of accretion through detachment faulting, overall creating the same amount of lithosphere on both flanks of the ridge. We interpret the observed changes in the time of the accretionary processes to reflect a decrease of the melt supply over the last ∼6 Myr. Key Points The southern intra-transform ridge segment in the St. Paul transform fault system, over the last ∼6 Myr is dominated by detachment faulting Several detachments have been split and partly transferred to the opposite ridge flank through ridge axis relocation The change in the accretionary processes, from Oceanic Core Complexes to mantle exhumation, suggests a decrease in the time of the melt supply Plain Language Summary The generation of new seafloor at mid-ocean ridges where cold underlying mantle delivers low magma supply has not been investigated over the long term. Here we present the analysis of new bathymetry, gravity, and rock sampling data over such a ridge segment located within the St. Paul Transform Fault system in the Equatorial Mid-Atlantic Ridge, which allowed us to bring constraints on its structure and evolution over the last ∼6 Myr. We show that this area evolves differently from previously described ridge segments of similar spreading rate. We observe the remnants of very large normal faults called detachment faults, which have been active for very long times, forming domes called oceanic core complexes. The fault surfaces have been dissected by further extensional deformation, until the plate motion became accommodated along a new detachment fault formed west of the previous plate boundary. The emergence lines of the detachment faults are observed on the eastern flank of the ridge segment. We also observe a change in time of the structures, from typical oceanic core complexes to shorter ridges formed by the exhumation of mantle rocks. We interpret these changes to possibly reflect a decrease in the melt supply in the last 6 Myr.

O transtorno do espectro autista (TEA) é uma forma de desenvolvimento ao longo da vida definida por critérios diagnósticos que incluem déficits de comunicação social e interação social e padrões restritos e repetitivos de comportamento, interesses ou atividades (APA, 2013). No Brasil estima-se que mais de dois milhões de pessoas tem Transtornos do Espectro Autista (TEA) (Paiva Junior, 2013). Sabe-se que tais transtornos se manifestam de forma individualizada e comprometem a comunicação e a socialização do indivíduo que os manifestam, o que torna desafiador o processo de sua inclusão social. Este projeto visa propor metodologia específica para o design gráfico de ferramentas voltadas ao ensino de crianças autistas. Pretende-se desenvolver conjuntos de atividades e disponibilizá-las nas versões física e digital. Dessa forma, será possível avaliar a resposta da criança autista quanto aos estímulos físicos e cognitivos, além dos aspectos relativos à aprendizagem.

Seismic rays traveling just below the Moho provide insights into the thermal and compositional properties of the upper mantle and can be detected as Pn phases from regional earthquakes. Such phases are routinely identified in the continents, but in the oceans, detection of Pn phases is limited by a lack of long-term instrument deployments. We present estimates of upper-mantle velocity in the equatorial Atlantic Ocean from Pn arrivals beneath, and flanking, the Mid-Atlantic Ridge and across several transform faults. We analyzed waveforms from 50 earthquakes with magnitude Mw>3.5, recorded over 12 months in 2012–2013 by five autonomous hydrophones and a broadband seismograph located on the St. Peter and St. Paul archipelago. The resulting catalog of 152 ray paths allows us to resolve spatial variations in upper-mantle velocities, which are consistent with estimates from nearby wide-angle seismic experiments. We find relatively high velocities near the St. Paul transform system (∼8.4 km s−1), compared with lower ridge-parallel velocities (∼7.7 km s−1). Hence, this method is able to resolve ridge-transform scale velocity variations. Ray paths in the lithosphere younger than 10 Ma have mean velocities of 7.9±0.5 km s−1, which is slightly lower than those sampled in the lithosphere older than 20 Ma (8.1 km±0.3 s−1). There is no apparent systematic relationship between velocity and ray azimuth, which could be due to a thickened lithosphere or complex mantle upwelling, although uncertainties in our velocity estimates may obscure such patterns. We also do not find any correlation between Pn velocity and shear-wave speeds from the global SL2013sv model at depths

The current known distribution of Omura’s whale includes the tropical and warm temperate waters of the western Pacific, Indian, and Atlantic Oceans. Evidence of their presence in the Atlantic Ocean is based on beach cast specimens found on the coasts of Mauritania (North Atlantic) and Northeastern Brazil (South Atlantic). The present study characterizes the occurrence of this species in the São Pedro and São Paulo Archipelago (SPSPA), on the mid-Atlantic ridge between South America and Africa, based on autonomous recording systems. Acoustic signals were similar, but not identical, to B. omurai vocalizations recorded off the coast of Madagascar. Although these signals were recorded for only 11 months, there are peaks in vocal activity between May and June in the vicinities of SPSPA, suggesting either a shift in distribution within the Atlantic equatorial waters or seasonality in the species’ vocal behavior in this region. The first acoustic records of Omura’s whales in the Equatorial Atlantic suggest that these animals may also use deep-water habitats, in addition to the shallow-water habitat use observed in other regions., A atual distribuição conhecida da baleia-de-Omura (Balaenoptera omurai) inclui as águas tropicais e temperadas quentes dos oceanos Pacífico ocidental, Índico e Atlântico. A evidência de sua presença no oceano Atlântico baseia-se em espécimes encalhados encontrados em praias da Mauritânia (Atlântico Norte) e do Nordeste do Brasil (Atlântico Sul). O presente estudo caracteriza a ocorrência dessa espécie no Arquipélago de São Pedro e São Paulo (ASPSP), localizado sobre a Dorsal Mesoatlântica entre a América do Sul e a África, com base em sistemas de monitoramento acústico passivo. Os sinais acústicos detectados foram similares, mas não idênticos, às vocalizações de B. omurai gravadas na costa de Madagascar. Embora esses sinais tenham sido registrados por apenas 11 meses, há picos na atividade vocal entre maio e junho nas proximidades do ASPSP, sugerindo uma mudança na distribuição da espécie nas águas equatoriais do Atlântico ou uma sazonalidade no comportamento vocal nessa região. Os primeiros registros acústicos das baleias-de-Omura no Atlântico Equatorial sugerem que esses animais também podem utilizar habitats de águas profundas, além de habitats de águas rasas como observado em outras regiões.

Deep microseismicity occurs in high-temperature ductile mantle mylonite shear zones resulting from semibrittle fracturing., Oceanic transform faults, a key element of plate tectonics, represent the first-order discontinuities along mid-ocean ridges, host large earthquakes, and induce extreme thermal gradients in lithosphere. However, the thermal structure along transform faults and its effects on earthquake generation are poorly understood. Here we report the presence of a 10- to 15-kilometer-thick in-depth band of microseismicity in 10 to 34 kilometer depth range associated with a high-temperature (700° to 900°C) mantle below the brittle lithosphere along the Romanche mega transform fault in the equatorial Atlantic Ocean. The occurrence of the shallow 2016 moment magnitude 7.1 supershear rupture earthquake and these deep microearthquakes indicate that although large earthquakes occur in the upper brittle lithosphere, a substantial amount of deformation is accommodated in the semibrittle mylonitic mantle that resides at depths below the 600°C isotherm. We also observe a rapid westward deepening of this band of seismicity indicating a strong lateral heterogeneity.

209 microearthquakes along the eastern Romanche transform fault were located using 17 deployedOBSsin 2019. Please find the details when the paper is published on Science Advances.

A strong edge effect is predicted at the intersections between long-offset transforms and mid ocean ridge segments. The Equatorial Atlantic hosts several megatransforms, where the connections of potentially low mantle temperatures due to the large lithospheric age contrast with melt production are poorly understood. The SMARTIES cruise focused on the Romanche transform that offsets the Mid Atlantic Ridge (MAR) laterally by 900 km with an age offset of 55 Ma. The eastern Ridge-Transform Intersection (RTI) markedly shows the effects of the lateral cooling of the ridge segment. To better understand the thermal regime at these complex domains, we acquired surface geophysical data and bathymetry of the area, and geological observations and sampling during 25 HOV Nautile dives. The integrated study of rock characteristics and of geophysical surveys allows tackling the connections between magmatism and tectonics. A network of 19 OBS was also deployed to study the seismic activity during the cruise in collaboration with the ILAB project.There is a striking change in deformation patterns along the ridge axis moving away from the transform southwards. The bathymetry is extremely complex, with several structural directions, partly resulting from transtension. A low melt supply is focused at the ridge axis resulting in a long oblique axial domain, that forms a relay zone between the roughly north-south ridge axis in the south and the area close to the transform fault, while the transform fault domain is highly complex. Trends oblique to both the main spreading axis direction and the transform fault direction are widespread. A clear Principal Transform Displacement Zone (PTDZ) can be followed as a long, near continuous alignment, on the seafloor of the wide Romanche valley. However, the valley morphology suggests a migration of the PTDZ and intense deformation within the transform domain. The RTI is complex and the position of the spreading axis clearly evolved with time, through at least two and possibly three eastward ridge jumps.Six Nautile dives explored the northern wall of the Romanche, the damaged zone of the transform fault, and the exceptionally deep nodal basin. The north wall exposes a very thick basalt unit covered with a thick layer of sediments. Eight dives explored the southern flank of the Romanche identifying fragments of old Oceanic Core Complexes (OCCs) formed by highly deformed peridotites, and a large OCC located at the RTI that exposes mylonitized peridotites and is dissected by several normal faults. The magmatic zones of the axial domain (nine dives) are formed by volcanic ridges affected by important tectonic activity. The dives show pillow and tube volcanic flows with intersecting faults. An oblique elongated faulted and sedimented ridge (2 dives) parallel to the oblique relay zone was shown to be of peridotitic nature Recent faults have been observed, as well as traces of high-T hydrothermal activity consistent with black-smoker type venting, recently overprinted by low temperature diffuse venting related to active faulting.

International audience; The Amsterdam-St. Paul (ASP) Plateau formed by interaction between the South East Indian Ridge (SEIR) and the ASP mantle plume during the last 10 Myr. The combined bathymetry and gravity-derived crustal thickness anomalies along the present and paleoaxes of the SEIR atop the plateau indicate: (1) a thicker crust and shallower water depth along the southern part of segment I2 during much of the last 10 Myr; (2) an earlier decrease (~1.4 Ma) in crustal thickness along the southern part of I2 compared to the northern part (~0.9 Ma) during the most recent period of reduced magmatism; (3) a topographic transition at ~0.7 Ma and during the last 0.1 Myr; and (4) an approximately uniform crustal thickness (8 km) along the entire I2 segment today. These observations require spatial and temporal variations in magma production during construction of the ASP Plateau over the last 3 Myr. We propose that during periods of weaker plume magma flux, spatial variations in upper mantle temperature and composition are small, and lead to small variations in crustal thickness along-axis. In contrast, during periods of stronger plume magma flux, spatial contrasts in upper mantle temperature and composition (fertility) are large, leading to significant variations in crustal thickness. Along-axis variations of 3 He/ 4 He, Δ8/4Pb, K/Ti, and Na 8 in "zero-age" basalts indicate that there is a gradient in the underlying mantle material, from a "common" mantle plume component (Δ8/4Pb~60) stronger in the north to a DUPAL component (Δ8/4Pb~110) dominating in the south. keywords: oceanic plateaus, plume-ridge interaction, Amsterdam St. Paul Plateau, South East Indian Ridge, geophysical and geochemical evidence key points:-Crustal architecture of the Amsterdam St. Paul Plateau records high and low plume flux stages during mantle plume-spreading ridge interaction-Plume magma flux decreased earlier in the south than in the north along a single spreading segment.-Along-axis differences in crustal thickness and Pb and He isotopes suggest both shallow mantle and plume heterogeneities.

Geophysical exploration in unconventional geothermal reservoir is challenging because of the lack of structures with specific geophysical signature such as a clay cap above volcanic geothermal reservoirs. The combination of several geophysical methods such as magnetotelluric (MT), gravity and seismic methods provides complementary insight into the geothermal reservoir. We present a joint inversion approach of ambient noise surface wave and gravity constrained by the 3D distribution of electrical resistivity. The method is applied to analyze the potential of unconventional deep geothermal resources in the French Massif Central (FMC). We coupled the resistivity, density and shear wave velocity with a linear correlation. We characterized the common properties in relation to the geological domains down to about 10–15 km. We validated the proposed approach on a synthetic model derived from models obtained from each independent geophysical method. The joint inversion limited the non-uniqueness of the gravity and the ambient noise tomography inversion and allow to recover the features of the synthetic models. We applied the method to real field data acquired in the Sioule Valley, Massif Central, France. The joint features observed in the geophysical models suggest a deep heat source associated with a possible shallow (∼6–8 km) brittle–ductile transition. A large fault zone, the Pongibaud Fault zone, seems to become listric and connect the surface to this transition zone to possibly constitute a permeable path for water circulation.

International audience

Tristan da Cunha is assumed to be the youngest subaerial expression of the Walvis Ridge hot spot. Based on new hydroacoustic data, we propose that the most recent hot spot volcanic activity occurs west of the island. We surveyed relatively young intraplate volcanic fields and scattered, probably monogenetic, submarine volcanoes with multibeam echosounders and sub-bottom profilers. Structural and zonal GIS analysis of bathymetric and backscatter results, based on habitat mapping algorithms to discriminate seafloor features, revealed numerous previously-unknown volcanic structures. South of Tristan da Cunha, we discovered two large seamounts. One of them, Isolde Seamount, is most likely the source of a 2004 submarine eruption known from a pumice stranding event and seismological analysis. An oceanic core complex, identified at the intersection of the Tristan da Cunha Transform and Fracture Zone System with the Mid-Atlantic Ridge, might indicate reduced magma supply and, therefore, weak plume-ridge interaction at present times., Here, the authors combine bathymetry and sediment echosound data to present a submarine, volcanic map of the Tristan de la Cunha region. They find that the youngest volcanic expression of the Tristan de la Cunha mantle plume is currently located to the (south-) west of the island.

Oceanic transform faults are fundamental features of the spreading processes and record changes in both the local-field and the far-field stresses, due to either local factors or plate motion changes. The study of the morphologic evidences of deformation they undergo due to these changes is key to understand the thermal and the mechanical structure of the oceanic lithosphere. Different features result from transform deformation. The large transverse ridges observed at several transforms form as a flexural response to extension at the transform or the fracture zone. The thermal heating of the lithosphere as well as the serpentinization of mantle rocks play a minor role in this uplift. Median ridges are also tectonic features formed due to compressive or extensional stresses inside the transform domain and serpentinization does not appear to play a major role in their uplift. At fast spreading ridges, extension inside the transform domain often results in the formation of “leaky transforms.” These morphologies are rare at slow spreading ridges, because the colder lithosphere does not favor the inception of intra-transform segments. However, large offset transforms, under severe changes in plate motions, may develop this geometry. Several factors will control the response of transform faults to changes in plate motion. A major one is the length of the offset, but the magnitude of the change in plate motion is also important. Minor changes will be easily accommodated by both small and large offset transforms, often through small deformations inside the transform valley. Conversely, larger changes may have small impact on small offset transforms but result in strong deformation at larger ones. Large offset transforms are slower to respond to kinematic changes than small offset ones. Mega-transforms may readjust even more slowly, thus forming a multifault complex boundary. At even larger offsets, the transform is no longer able to adjust to severe changes and will be abandoned. Local stresses such as mantle flow and thermal contraction of the lithosphere may induce significant topography at transform faults through small bends of the principal transform displacement zone (PTDZ) inside the transform domain, thus resulting in localized transpression and transtension.

This article presents the results of quantitative and qualitative study which used extracted data from the official website of the Federal University of Alagoas (UFAL). Its objective is to investigate the teaching of intellectual property and entrepreneurship in the curricula of “stricto sensu” graduate syllabus of UFAL. Also investigates the number of certified and updated research groups in the Research Group Directory (DGP) maintained by the National Council for Scientific and Technological Development (CNPq) related to the subject and linked to UFAL. Considering the literature and the data found, this paper concludes for the need of new studies to investigate why few graduate syllabus offer disciplines related to the teaching of intellectual property and entrepreneuship in UFAL. Este artigo apresenta os resultados de pesquisa quantitativa-qualitativa realizada no sítio eletrônico da Universidade Federal de Alagoas (UFAL). Objetiva a análise das ementas das disciplinas veiculadas nos projetos dos programas de pós-graduação stricto sensu da UFAL, acerca do ensino da temática da propriedade intelectual e do empreendedorismo. Investiga também a quantidade de grupos de pesquisa certificados e atualizados junto ao Diretório de Grupos de Pesquisa do Conselho Nacional de Desenvolvimento Científico e Tecnológico (DGP/CNPq), relacionados com os referidos temas e vinculados à UFAL. Considerando o levantamento da literatura e os dados obtidos, conclui-se pela necessidade de mais estudos sobre as causas que ensejam a pequena quantidade de cursos de pós-graduação stricto sensu que ofertam disciplinas relacionadas com o ensino da propriedade intelectual e do empreendedorismo na UFAL.

International audience

O presente estudo teve como objetivo produzir um video educativo para sensibilizar os profissionais que compoem equipes de enfermagem quanto ao uso de equipamentos de protecao individual. Para tal, foram realizadas oficinas com profissionais que trabalham em uma unidade de emergencia em um hospital domunicipio do Rio de Janeiro para identificar os EPIs nao utilizados e os motivos dessa decisao. As falas dos profissionais foram gravadas em audio, transcritas e analisadas para compor o roteiro do video. O motivo mais significativo elencado pelo nao uso dos EPIs foi o desconforto que causam aos profissionais da equipede enfermagem. Os enfermeiros avaliaram positivamente o video quanto a qualidade da imagem, som e mensagem proposta. Espera-se que este material educativo seja utilizado em oficinas de educacao permanente, permitindo uma reflexao quanto aos riscos a que os profissionais de enfermagem estao expostos no setor de emergencia hospitalar.

This study investigates the magnetic and gravity signatures and associated seismic character of hyper-extended, exhumed and embryonic oceanic domains along the conjugate Iberia–Newfoundland rifted margins. As these margins have been drilled down to basement along their distal parts, it is possible to explore and test different geophysical techniques and interpretations. The aims of this work are twofold: (1) to investigate the location and nature of the two main marginal boundaries—the necking zone and the J Anomaly, which define the limits of major domains; and (2) to map the lateral variations of gravity and magnetic signatures and their detailed correlation with seismic data, from the proximal margin until the first unequivocal oceanic magnetic anomaly (e.g. C34 Anomaly). The results point out that the J Anomaly corresponds to a first-order tectono-magmatic boundary, with a basement formed by polyphase magmatism. It marks the boundary between the exhumed mantle domain, with little magmatic additions, from a domain oceanwards that reveals comparable trends, frequencies and a general magnetic pattern at both sides of the Atlantic, suggesting a coeval evolution. We propose that the domain between the J and the C34 Anomalies was formed by an embryonic spreading system, with intermittent budgets of magma, similar to those observed at very slow spreading systems. The J Anomaly may thus correspond to the location of lithospheric breakup though its origin and the nature of the domain oceanwards remains to be constrained.

Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults(1-4), and, along transforms, by transtension due to changes in ridge/transform geometry(5,6). Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic(7,8). Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since similar to 10 million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform fault creating restraining stepovers. An anticlockwise change in plate motion at similar to 11 million years ago(5) initially favoured extension in the left-stepping transform, triggering the formation of a transverse ridge, later uplifted through transpression, forming the St Peter and St Paul islets. Enhanced melt supply at the ridge axis due to the nearby Sierra Leone thermo chemical anomaly(9) is responsible for the robust response of the northern Mid-Atlantic Ridge segment to the kinematic change. The long-lived process at the origin of the compressive stresses is directly linked to the nature of the underlying mantle and not to a change in the far-field stress regime.

This paper presents geophysical and geochemical evidence for the possible existence of cold, subducted lithosphere beneath the Saint Paul Fracture Zone of the Equatorial Atlantic Ocean. The ocean floor along the fracture zone is characterized by a high percentage of abyssal peridotites. The abyssal peridotites were emplaced by tectonic uplift of the oceanic lithosphere. The top of the ridge is exposed at Saint Peter and Saint Paul islets. The Os isotopic composition of these abyssal peridotites indicate the presence of old depleted mantle material in this region with Re-depletion model ages (T RD) from 0.32 to 1.1Ga. Melt inclusions in plagioclase phenocrysts of the MORB close to this location have boninitic composition, suggesting that some basalts originated from low-degree mantle melting. The global tomography models show fast seismic velocities in the upper and lower mantle of the Equatorial Atlantic Ocean, consistent with the presence of cold subducted lithosphere. The range of Re-depletion model ages are consistent with paleo-reconstructions of plate motion, suggesting that the fossil subducted slab was formed during the closure of both the Iapetus and the Rheic oceans. O presente trabalho mostra evidências geofísicas e geoquímicas para a possível existência de fragmentos frios do manto originados da placa subductada abaixo da Zona de Fratura de São Paulo no Oceano Atlântico Equatorial. A planície abissal desta área é caracterizada por uma abundância de rochas peridotíticas, com presença de poucas rochas basálticas originadas de baixo grau de fusão parcial. Arquipélago de São Pedro e São Paulo se localiza no topo de uma elevação morfológica com mais de 4000m de altura, constituída por peridotitos abissais, posicionados por um soerguimento tectônico da litosfera oceânica. A razão isotópica de Os dos peridotitos da Zona de Fratura de São Paulo indica a presença de materiais originados de antigo manto depletado nesta região com as idades modelo de 0.32 a 1.1Ga. As inclusões de magma trapeadas nos fenocristais de plagioclásio nos basalto da cadeia meso-oceânica pouco mais ao sul apresentam composição boninítica, típicas de zona de arco. Os modelos da tomografia mundial do manto demonstram alta velocidade sísmica tanto no manto superior quanto no inferior do Oceano Atlântico Equatorial, o que corrobora a interpretação da presença de placa subductada de baixa temperatura. As idades do modelo de depleção de Re dos peridotitos são consistentes com a reconstituição de movimento das placas, sugerindo que os fragmentos de placa fóssil subductada são provenientes do fechamento tanto do Oceano Iapetus como o do Oceano Rheic.

International audience; In order to understand the subsurface stratigraphy and structure of the northwest end of the Turkana Basin, Northern Kenya Rift, we used 2-D joint inversion of magnetotelluric (MT) and gravity data acquired along 3 profiles perpendicular to the main Murua Rith-Lapur Rift Border Fault. The regional geology is characterized by a basement of Precambrian age overlain by a ≤500-m thick sandstone formation named the Lapur Sandstone of upper Cretaceous-lower Eocene in age, covered by thick rhyolitic and basaltic lavas of late Eocene-middle Miocene age, known as the “Turkana Volcanics”. Final interpretation of the resistivity and density models, until 5 km depth, obtained by the joint inversion approach confirms the previous general knowledge about the half-graben geometry of the northern part of the Turkana Basin. The main Murua Rith-Lapur Rift Border Fault is well identified by both gravity and MT. At least, two other important secondary faults without surface expression are also identified. A new small half-graben basin, named the Kachoda Basin, parallel to the main Turkana Basin and filled by 1.5 km of sediments, has been also characterized. This study also highlights strong thickness variations of the three main geological units that could be expected in the subsurface of the Turkana Basin. For example, the sedimentary Nachukui and Kibish Formations reach up to >3 km in thickness at the eastern end of the north and central profiles. Lateral variations of the topography of the Precambrian basement are also evidenced. Conceptual geological models, which result from the combination of the obtained density and resistivity models as well as from geological and reflection seismic data, are proposed. In such an area of intensive and promising oil exploration, these models are essential in terms of identification of reservoirs, source rocks and trapping mechanisms.

The magnetic study of Saint Paul fracture zone is part of the COLMEIA Project (Complex Mantle Exhumation and Intra-transform Accretion), and deals with the magnetic data collected during the oceanographic cruise on January-February of 2013. Firstly, the data was processed and the initial analysis was done, getting an observed magnetic anomalies grid. The second focus was the calculation of simple theoretical models able to simulate an homogeneous crust with constant spreading, and topography and two magnetization possibilities: a constant value or a function of age. Therefore, the processed models represent a simple dynamic. The residuals, i.e., the differences between the observed and theoretical signal, show variations in composition, topography and polarity. Differences between models will be presented and discussed. The interpretation of the residual anomalies, compared with other geophysical and geological data, will be able to partially model the geodynamical processes in the region, specifically in the area of St. Paul’s fracture and the St. Peter and St. Paul’s Archipelago. The interpretation had already started and this work aims to present the first ideas from the magnetic analysis of COLMEIA cruise.

The COLMEIA Project is an international collaboration between France and Brazil involving several universities and research institutes. One of the objectives of this project is to study the tectonic evolution and to understand the processes that result in the exhumation of the ultramafic body which composes the Sao Pedro e Sao Paulo archipelago, as wellasthe magmatism and tectonics of this part of the Mid-Atlantic Ridge, especially for the recent geologic time. The work is essential to understand the evolution of the Equatorial Atlantic Ocean. A fundamental part of thestudy targets the detailed analysis of sites that indicate recent off-axis deformation, since these faults could work as pathways for hydrothermal fluids, which is important to understand hydrothermalism in sediment environments. This paper presents the preliminary results of the analysis of the seismic data acquired during the COLMEIA cruise. The first step was to process the seismic lines in the north part of the area covered during the cruise, where the St. Peter peridotite ridge is located. The software used, Sispeed v5.5, was developed by the IFREMER and available for use at the laboratory. The seismic configuration on the COLMEIA cruise used 24 hydrophones and 2airguns. The value of 1500 m/s was assigned for the velocity of the sound wave on the water and sediments. After processing, interpretation was performed using a specific software called Kingdom 8.5. During the first part of the interpretation, the focus was to identify the most important seismic horizons, such as the basement and major seismic horizons inside the sediment infill. The seismic profiles showed a strongly rugged bathymetry. One can easily note that the area is full of geological depressions, representing fracture zones, forming small, elongated basins. These features, that during millions of years gathered sediments, most of them hemipelagic and volcanogenic, allow to infer the age of each sector of the study area and shows some deformation at their upper part. Some difficulties were faced, due to the strongly rugged bathymetry in the area, during the interpretation of the seismic profiles. Thus, some seismic attributes were used to find where is the true ocean floor. One method used was the envelope, since this seismic attribute represents the instantaneous energy of the signal and its magnitude is proportional to the reflection coefficient.

A integração de dados geológicos e geofísicos permitiu um melhor entendimento da inter-relação entre estruturas oceânicas e continentais. Fenômenos tectônicos e magmáticos do Meso-Cenozóico do Sudeste Brasileiro podem ter sido condicionados pelo prolongamento das zonas de fratura oceânicas em direção à margem continental. O foco deste trabalho é a evolução da Zona de Fratura de Vitória-Trindade (ZFVT). A Zona de Fratura de Vitória-Trindade (ZFVT), localizada na latitude de 18º40' na Cordilheira Mesoatlântica (CMA), foi mapeada utilizando-se sísmica de reflexão, gravimetria e isócronas magnéticas. A ZFVT na CMA corresponde a um deslocamento axial em torno de 6 km, configurando uma descontinuidade de segunda ordem. O segmento assísmico da ZFVT é definido por uma depressão gravimétrica de direção E-W. Sua extensão para oeste corresponde à Cadeia Vitória-Trindade, representada por altos topográficos individualizados, que limitam desníveis crustais de mais de 400 m e províncias sedimentares de características e espessuras distintas. Esta região cortada pela intrusão de diques (alguns aflorando na superfície) e sills, indica instabilidade tectônica com a movimentação de falhas e ocorrência de estruturas transpressivas (estruturas em flor), elevando toda a coluna sedimentar incluindo o assoalho oceânico. Estas observações sugerem reativações recentes da crosta oceânica com esforços alternantes, ora compressivos ora distensivos, associados a vulcanismos e falhamentos normais. Evidências geológicas e geofísicas, além do mapeamento do alinhamento de epicentros de terremotos, sugerem que o prolongamento da ZFVT está relacionado ao Alto de Vitória e ao tectonismo e magmatismo na porção emersa, representado pelo Lineamento Sismo-Magmático Alcalino Trindade-Paxoréu / Alto do Paranaíba. Propõe-se que a ZFVT atuou e continua atuando como conduto para o magmatismo da Pluma Mantélica de Trindade. The integration of geological and geophysical data allowed a better understanding of the inter-relation between the oceanic and continental structure. Tectonic and magmatic phenomena of the Meso-Cenozoic were probably related to the prolongation of oceanic fracture zones into the Brazilian Southeast continental margin. This work will focus on the behaviour of the Vitória-Trindade Fracture Zone (VTFZ). The Vitória-Trindade Fracture Zone (VTFZ), located at 18º40S in the Mid-Atlantic Ridge (MAR), was defined by seismic, gravity and magnetic isochrones. At the MAR axis the VTFZ corresponds to a second-order discontinuity, with a 6 km axial offset. Away from the ridge axis, potential field data shows a gravimetric depression in E-W direction, which represents the asseismic portion of the VTFZ. Towards the Brazilian Continental Margin there is a series of topographic highs defining the Vitória-Trindade Chain, which is divided into distinct sedimentary thickness and tectonic domains. This area is cut by sills and dikes, indicating tectonic instability, remobilization of faults and strike-slip tectonics which has uplifted the entire sedimentary column, including the oceanic bottom. All of these observations suggest recent oceanic crust reactivation with alternations of compressive and extensional stress associated with volcanism and normal faulting. Geological and geophysical studies, in addition to mapping the earthquakes epicenters, suggest that the continuation of the VTFZ that occurs onland is related to the Vitória High and to tectonic and volcanic activities, which are expressed by the Trindade-Paxoréu /Alto do Paranaíba Alkalic Magmatic and Seismic Lineaments. We propose that the VTFZ acts as a pathway for the magma generated by the Trindade Mantle Plume.

International audience; The interaction between the Foundation hotspot and the Pacific-Antarctic Ridge (South Pacific) is one of the two known cases where a ridge is approaching a hotspot. This ridge-hotspot relative movement results in a change in the morphology of the volcanoes along the chain as the age of the lithosphere at the time of edifice formation progressively diminishes. Four hundred kilometers west of the Pacific-Antarctic Ridge axis, volcanism is distributed along two sub-parallel lines of volcanoes, separated by distances diminishing from~100 km at the west to~50 km near the axis of the ridge. The magnetic anomalies mapped on this part of the chain show a pattern clearly dominated by the magnetic signature of the seamounts. The anomalies were forward modeled using a remanent magnetization of normal or reversed polarity within the volcano topography. The resulting pattern of normal and reversed magnetization is consistent with the intervals of the geomagnetic polarity time scale for the last 5 Ma, the age of the oldest studied volcano. These magnetic anomalies therefore represent an independent means of dating the volcanic edifices. The ages deduced from the modeling are consistent with the hypothesis of volcanoes built by a hotspot on the fast moving Pacific plate and are in good agreement with the published radiometric dates, although these dates tend to correspond to the late constructional stages of the edifices. The differences between magnetic and radiometric ages suggest that the average time span to build a volcano of the Foundation chain is about 1 million years, in agreement with other intraplate edifices. The difference between the magnetic ages of the seamounts and of the underlying crust, both deduced from the magnetic anomaly analysis, show that the ridge has approached the hotspot at a rate of 40 km/Ma.

A geophysical survey in the eastern Gulf of Aden, between the Alula–Fartak (52°E) and the Socotra (55°E) transform faults, was carried out during the Encens–Sheba cruise. The conjugate margins of the Gulf are steep, narrow and asymmetric. Asymmetry of the rifting process is highlighted by the conjugate margins (horst and graben in the north and deep basin in the south). Two transfer fault zones separate the margins into three segments, whereas the present-day Sheba Ridge is divided into two segments by a transform discontinuity. Therefore segmentation of the Sheba Ridge and that of the conjugate margins did coincide during the early stages of oceanic spreading. Extensive magma production is evidenced in the central part of the western segment. Anomaly 5d was identified in the northern and southern parts of the oceanic basin, thus confirming that seafloor spreading in this part of Gulf of Aden started at least 17.6 Ma ago.

Located in the South Pacific, between latitudes 33°S and 38°S and longitudes 120°W and 125°W, the extinct Selkirk microplate was first described as originating from lithosphere transferred from the Nazca plate to the Pacific plate [Earth Planet. Sci. Lett. 113 (1992) 293]. Multibeam bathymetry data, backscatter imagery and magnetic data obtained in 1997 during the Foundation Hotline cruise permit a more complete and detailed characterisation of the evolution of this paleomicroplate. The western boundary of the paleomicroplate is a fossil-spreading axis composed by two segments presenting two southward propagations and fan-shaped opening. The eastern boundary of the paleomicroplate is formed by a northward-propagating rift. In the present-day, only the western part of the fan-shaped sequence is present in the Pacific plate. According to satellite altimetry data, the northern boundary is a complex compressive domain formed by N110 ridges and troughs. The southern boundary is located along the Mocha fracture zone. Our magnetic interpretation suggests that this microplate has been active between chron 6C (24 Ma) and chron 6Ar (anomaly 6A, reverse period; 20.8 Ma). The last stage of the Selkirk microplate evolution is marked by a compression in the southern boundary and a sinistral shearing along an associated N45 structure located in the microplate. These observations imply the transfer of the eastern southern boundary of the microplate, previously located along the Mocha fracture zone, to these complex structures. The observed structures imply a change of the microplate rotation axis for this last stage, leading to the locking of the microplate and the transfer of all the spreading to the eastern boundary.

In NE Botswana, the Karoo dykes include a major N110° dyke swarm known as the Okavango giant dyke swarm (ODS/N110°) and a second smaller set of N70° dykes belonging to the Sabi-Limpopo dyke swarm (SLDS/N70°). New 40Ar/39Ar plagioclase dating of Karoo dolerites of the giant ODS/N110° and the SLDS/N70° in NE Botswana yield plateau ages between 179.6±1.2 and 178.4±1.1 Ma. Our data are concordant with previous 40Ar/39Ar ages for Northern Karoo dykes and lava flows exposed in western Zimbabwe. The data are tightly clustered, indicating a short-lived (179–181 Ma) flood basalt magmatism in this region. The new radiometric dates allow the definition of a diachronous Jurassic flood basalt activity in southern Africa. A significant south to north younging at the scale of the Karoo igneous province correlates with a chemical zonation from low-Ti (south) to high-Ti (north) mafic rocks. Structural measurements on the ODS/N110° and SLDS/N70° Karoo dykes of NE Botswana suggest that: (1) most of the host fractures are inherited Precambrian structures; (2) dyke emplacement occurred under unidirectional tensional stresses; (3) significant syn- and post-volcanic extensional tectonics are lacking. Combined with regional geology, these geochronological and structural data do not confirm unambiguously the triple-junction hypothesis usually put forward to support a mantle plume model for the evolution of the Karoo igneous province, prior to Gondwana breakup.

SUMMARY The youngest volcanoes of the Foundation volcanic chain were built on a plate less than 5 Myr near the Pacific‐Antarctic ridge (PAR) axis. The progressive approach of the spreading ridge to the hotspot during the last 10 Myr resulted in the building of the edifices upon a progressively younger plate. Estimates of the effective elastic thickness, Te, using two independent methods show that the elastic thickness of the plate diminishes towards the spreading ridge, from 5‐3 km to 2‐0 km. The spatial variation of Te correlates with a significant change in both the morphology and the volume of the volcanoes, suggesting an important control of the elastic thickness on the volcanic processes. The reduction in Te also explains conveniently the reduction in the distance between the North and the South Systems, the double volcanic line that characterizes the young part of the Foundation chain, in the direction of young loading ages. The South System formed at the top of a flexural bulge created by the emplacement of the North System, the main volcanic line. The low Te estimate for the South System and the shape of the Bouguer anomalies confirm this model. The effective elastic thicknesses obtained in this study are well matched by isotherms between 200 ◦ C and 300 ◦ C and support the hypothesis of a weak plate. Three mechanisms possibly acted to lower the plate rigidity: Re-heating of a ‘normal’ plate by the hotspot (North System); local fracturing (South System) and the creation of a thin lithosphere at the PAR axis by the coupling of a hotspot and the ridge-related melting zones (near-ridge volcanoes).

International audience; Multiple geological processes affect the distribution of hydrothermal venting along a mid-ocean ridge. Deciphering the role of a specific process is often frustrated by simultaneous changes in other influences. Here we take advantage of the almost constant spreading rate (65–71 mm/yr) along 2500 km of the Southeast Indian Ridge (SEIR) between 77 E and 99 E to examine the spatial density of hydrothermal venting relative to regional and segment-scale changes in the apparent magmatic budget. We use 227 vertical profiles of light backscatter and (on 41 profiles) oxidation-reduction potential along 27 first and second-order ridge segments on and adjacent to the Amsterdam-St. Paul (ASP) Plateau to map p h , the fraction of casts detecting a plume. At the regional scale, venting on the five segments cross-ing the magma-thickened hot spot plateau is almost entirely suppressed (p h 5 0.02). Conversely, the com-bined p h (0.34) from all other segments follows the global trend of p h versus spreading rate. Off the ASP Plateau, multisegment trends in p h track trends in the regional axial depth, high where regional depth increases and low where it decreases. At the individual segment scale, a robust correlation between p h and cross-axis inflation for first-order segments shows that different magmatic budgets among first-order segments are expressed as different levels of hydrothermal spatial density. This correlation is absent among second-order segments. Eighty-five percent of the plumes occur in eight clusters totaling 350 km. We hypothesize that these clusters are a minimum estimate of the length of axial melt lenses underlying this section of the SEIR.