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| Registros recuperados: 333 | |
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| Castaneda, Isla S.; Caley, Thibaut; Dupont, Lydie; Kim, Jung-hyun; Malaize, Bruno; Schouten, Stefan. |
| In this study we investigate Pleistocene vegetation and climate change in southern East Africa by examining plant leaf waxes in a marine sediment core that receives terrestrial runoff from the Limpopo River. The plant leaf wax records are compared to a multi-proxy sea surface temperature (SST) record and pollen assemblage data from the same site. We find that Indian Ocean SST variability, driven by high-latitude obliquity, exerted a strong control on the vegetation of southern East Africa during the past 800,000 yr. Interglacial periods were characterized by relatively wetter and warmer conditions, increased contributions of C3 vegetation, and higher SST, whereas glacial periods were marked by cooler and arid conditions, increased contributions of C4... |
| Tipo: Text |
Palavras-chave: Vegetation; Africa; N-alkane; Pollen; Subtropical Front; Mid-Brunhes. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00345/45601/45215.pdf |
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| Badji, Rabia; Charvis, Philippe; Bracene, Rabah; Galve, Audrey; Badsi, Madjid; Ribodetti, Alessandra; Benaissa, Zahia; Klingelhoefer, Frauke; Medaouri, Mourad; Beslier, Marie-odile. |
| For the first time, a deep seismic data set acquired in the frame of the Algerian-French SPIRAL program provides new insights regarding the origin of the westernmost Algerian margin and basin. We performed a tomographic inversion of traveltimes along a 100-km-long wide-angle seismic profile shot over 40 ocean bottom seismometers offshore Mostaganem (Northwestern Algeria). The resulting velocity model and multichannel seismic reflection profiles show a thin (3-4 km thick) oceanic crust. The narrow ocean-continent transition (less than 10 km wide) is bounded by vertical faults and surmounted by a narrow almost continuous basin filled with Miocene to Quaternary sediments. This fault system, as well as the faults organized in a negative-flower structure on the... |
| Tipo: Text |
Palavras-chave: Seismic tomography; Continental margins: transform; Crustal structure; Africa; Europe.. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00255/36670/35278.pdf |
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| Rodriguez, Mathieu; Maleuvre, Clement; Jollivet-castelot, Martin; D'Acremont, Elia; Rabaute, Alain; Lafosse, Manfred; Ercilla, Gemma; Vazquez, Juan-tomas; Alonso, Belen; Ammar, Abdellah; Gorini, Christian. |
| The active Eurasia-Nubia plate boundary runs across the Alboran Sea in theWestern Mediterranean Sea, where the connection between the Atlantic and Mediterranean water masses occurs. Earthquakes above magnitude M-w > 6 may favour the occurrence of landslides within contouritic drifts in the Alboran Sea. A compilation of recent multibeam data reveals for the first time the distribution of slope failures along the Xauen-Tofino banks, in the southern Alboran Sea. Here, we provide a detailed mapping and description of the morphology of eight Holocene landslides, including volume estimations of the failed mass and the related mass transport deposits (MTDs). The most voluminous landslide mobilized similar to 0.5 km(3) of sediment at the initial stage of slope... |
| Tipo: Text |
Palavras-chave: Tsunamis; Submarine landslides; Submarine tectonics and volcanism; Africa. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00474/58560/61118.pdf |
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| Adimah, N I; Padhy, S. |
| The unusual complex lithospheric structure of Madagascar is a product of a number of important geological events, including: the Pan-African Orogeny, episodes of Late Cenozoic intraplate volcanism and several phases of deformation and metamorphism. Despite this rich history, its detailed crustal structure remains largely underexplored. Here, we take advantage of the recently obtained data set of the RHUM-RUM (Réunion Hotspot and Upper Mantle–Réunions Unterer Mantel) seismological experiment, in addition to previously available data sets to generate the first Rayleigh wave group velocity maps across the entire island at periods between 5 and 30 s using the ambient noise tomography technique. Prior to preliminary data preparation, data from Ocean Bottom... |
| Tipo: Text |
Palavras-chave: Seismic tomography; Africa; Crustal structure; Surface waves and free oscillations; Seismic noise.. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00600/71184/69539.pdf |
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| Plasman, M.; Tiberi, C.; Ebinger, C.; Gautier, S; Albaric, J.; Peyrat, S.; Deverchere, Jacques; Le Gall, B.; Tarits, Pascal; Roecker, S.; Wambura, F.; Muzuka, A.; Mulibo, G.; Mtelela, K.; Msabi, M.; Kianji, G.; Hautot, S.; Perrot, J.; Gama, R.. |
| Rifting in a cratonic lithosphere is strongly controlled by several interacting processes including crust/mantle rheology, magmatism, inherited structure and stress regime. In order to better understand how these physical parameters interact, a 2 yr long seismological experiment has been carried out in the North Tanzanian Divergence (NTD), at the southern tip of the eastern magmatic branch of the East African rift, where the southward-propagating continental rift is at its earliest stage. We analyse teleseismic data from 38 broad-band stations ca. 25 km spaced and present here results from their receiver function (RF) analysis. The crustal thickness and Vp/Vs ratio are retrieved over a ca. 200 x 200 km(2) area encompassing the South Kenya magmatic rift,... |
| Tipo: Text |
Palavras-chave: Time-series analysis; Continental tectonics: extensional; Africa; Crustal imaging. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75026/75673.pdf |
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| Demets, C.; Merkouriev, S.; Sauter, D.. |
| We present the first estimates of Southwest Indian Ridge (SWIR) plate motions at high temporal resolution during the Quaternary and Neogene based on nearly 5000 crossings of 21 magnetic reversals out to C6no (19.72 Ma) and the digitized traces of 17 fracture zones and transform faults. Our reconstructions of this slow-spreading mid-ocean ridge reveal several unexpected results with notable implications for regional and global plate reconstructions since 20 Ma. Extrapolations of seafloor opening distances to zero-age seafloor based on reconstructions of reversals C1n (0.78 Ma) through C3n.4 (5.2 Ma) reveal evidence for surprisingly large outward displacement of 5 ± 1 km west of 32°E, where motion between the Nubia and Antarctic plates occurs, but 2 ± 1 km... |
| Tipo: Text |
Palavras-chave: Plate motions; Africa; Antarctica. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00296/40684/39674.pdf |
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| Tsang-hin-sun, Eve; Evain, Mikael; Julia, J; Lamarque, G; Schnurle, Philippe. |
| This study investigates the seismic structure and anisotropy in the crust beneath Madagascar and south-eastern Africa, using receiver functions. The understanding of seismic anisotropy is essential for imaging past and present deformation in the lithosphere-asthenosphere system. In the upper mantle, seismic anisotropy mainly results from the orientation of olivine, which deforms under tectonic (fossil anisotropy) or flow processes (in the asthenosphere). In the crust, the crystallographic alignment of amphiboles, feldspars(plagioclase) or micas or the alignment of heterogeneities such as fractures, add to a complex geometry, which results in challenges to understanding the Earth's shallow structure. The decomposition of receiver functions into back-azimuth... |
| Tipo: Text |
Palavras-chave: Crustal seismic anisotropy; Inherited structural heterogeneities; Crustal stress; Receiver function harmonics; Madagascar; Africa; EARS. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00686/79843/82668.pdf |
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| Bouyahiaoui, B.; Sage, F.; Abtout, A.; Klingelhoefer, Frauke; Yelles-chaouche, K.; Schnuerle, P.; Marok, A.; Deverchere, Jacques; Arab, M.; Galve, A.; Collot, J.y.. |
| We determine the deep structure of the eastern Algerian basin and its southern margin in the Annaba region (easternmost Algeria), to better constrain the plate kinematic reconstruction in this region. This study is based on new geophysical data collected during the SPIRAL cruise in 2009, which included a wide-angle, 240-km-long, onshore–offshore seismic profile, multichannel seismic reflection lines and gravity and magnetic data, complemented by the available geophysical data for the study area. The analysis and modelling of the wide-angle seismic data including refracted and reflected arrival travel times, and integrated with the multichannel seismic reflection lines, reveal the detailed structure of an ocean-to-continent transition. In the deep basin,... |
| Tipo: Text |
Palavras-chave: Tomography; Composition of the oceanic crust; Continental margins; Divergent; Africa. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00269/38016/36103.pdf |
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| Mihoubi, A.; Schnurle, Philippe; Benaissa, Z.; Badsi, M.; Bracene, R.; Djelit, H.; Geli, Louis; Sage, F.; Agoudjil, A.; Klingelhoefer, Frauke. |
| This study presents the results of a deep seismic survey across the north Algerian margin, based on the combination of 2-D multichannel and wide-angle seismic data simultaneously recorded by 41 ocean bottom seismometers deployed along a north-south line extending 180 km off Jijel into the Algerian offshore basin, and 25 land stations deployed along a 100-km-long line, cutting through the Lesser Kabylia and the Tellian thrust-belt. The final model obtained using forward modelling of the wide-angle data and pre-stack depth migration of the seismic reflection data provides an unprecedented view of the sedimentary and crustal structure of the margin. The sedimentary layers in the Algerian basin are 3.75 km thick to the north and up to 4.5-5 km thick at the... |
| Tipo: Text |
Palavras-chave: Tomography; Continental margins: divergent; Africa. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00217/32836/32150.pdf |
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| O'Connor, David; Stacy‐dawes, Jenna; Muneza, Arthur; Fennessy, Julian; Gobush, Kathleen; Chase, Michael J.; Brown, Michael B.; Bracis, Chloe; Elkan, Paul; Zaberirou, Abdoul Razazk Moussa; Rabeil, Thomas; Rubenstein, Dan; Becker, Matthew S.; Phillips, Samantha; Stabach, Jared A.; Leimgruber, Peter; Glikman, Jenny A.; Ruppert, Kirstie; Masiaine, Symon; Mueller, Thomas. |
| Giraffe populations have declined in abundance by almost 40% over the last three decades, and the geographic ranges of the species (previously believed to be one, now defined as four species) have been significantly reduced or altered. With substantial changes in land uses, loss of habitat, declining abundance, translocations, and data gaps, the existing geographic range maps for giraffe need to be updated. We performed a review of existing giraffe range data, including aerial and ground observations of giraffe, existing geographic range maps, and available literature. The information we collected was discussed with and validated by subject‐matter experts. Our updates may serve to correct inaccuracies or omissions in the baseline map, or may reflect actual... |
| Tipo: Text |
Palavras-chave: Aerial survey; Africa; Decline; Endangered; Geographic range; Giraffe; Spatial ecology. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00509/62106/66281.pdf |
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| Baldé,Mamadou C; Chippaux,Jean-Philippe; Boiro,Mamadou Y; Stock,Roberto P; Massougbodji,Achille. |
| Background In Guinea Elapids are responsible for 20% of envenomations. The associated case fatality rate (CFR) ranged 15-27%, irrespective of treatment. Results We studied 77 neurotoxic envenomations divided in 3 groups: a set of patients that received only traditional or symptomatic treatments, and two other groups that received either 2 or 4 initial vials of Antivipmyn® Africa renewed as necessary. CFR was 27.3%, 15.4% and 17.6%, respectively. Although antivenom treatment was likely to reduce CFR, it didn’t seem to have an obvious clinical benefit for the patients, suggesting a low treatment efficacy. Mean delay to treatment or clinical stages were not significantly different between the patients who recovered and the patients who died, or between... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Elapid; Neurotoxins; Treatment; Antivenom; Guinea; Africa. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1678-91992013000100304 |
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| Registros recuperados: 333 | |
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