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| Registros recuperados: 14 | |
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| Patriat, Martin; Klingelhoefer, Frauke; Aslanian, Daniel; Contrucci, Isabelle; Gutscher, Marc-andré; Talandier, Jacques; Avedik, Felix; Francheteau, Jean; Weigel, Wilfried. |
| [1] In French Polynesia, the young (< 5Ma) Society Islands appear to result from intraplate volcanism, while the old (>50 Ma) Tuamotu plateau was likely created at or near the ridge axis. The structure of the crust between those two archipelagoes is constrained by a 300 km long refraction seismic profile. Crustal and upper mantle arrivals recorded by 6 OBHs and 3 land stations were used to provide a 2D model of the crust. Results of our study, combined with that of Grevemeyer et al. [2001] show a slight flexure below the Tahiti apron, while a deep crustal root (21 km) underlies the Tuamotu plateau. These structures reflect the different modes of load emplacement and compensation mechanisms between these two volcanic edifices, consistent with an... |
| Tipo: Text |
Palavras-chave: Volcanic Islands; Flexure; Hotspot; Refraction methods; French Polynesia. |
| Ano: 2002 |
URL: http://archimer.ifremer.fr/doc/2002/publication-621.pdf |
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| Bonneville, Alain; Dosso, Laure; Hildenbrand, Anthony. |
| We are presenting a new set of K/Ar ages and geochemical analyses obtained on deep-sea samples dredged in 1999 on several seamounts of the Cook-Austral volcanic chains in the Pacific Ocean. The new geochemical results, together with published data on island samples, allow us to reveal a time evolution of the mantle source composition as well as an increase in geochemical variability of the superplume responsible for the regional South Pacific Superswell. Three identified volcanic stages of 58-40, 33-20 and 20-0 Ma are identified with signatures of mantle reservoir composition varying from close to C to N-MORB-types and C/HFMU-type, respectively. Using a geodynamic reconstruction for the most recent volcanic period, from 20 Ma to present, three hotspot... |
| Tipo: Text |
Palavras-chave: Hotspot; Cook Austral; Seamount ages; Geochemical sources; South Pacific Superswell; Mantle plume. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1559.pdf |
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| Charvis, P; Recq, M; Operto, S; Brefort, D. |
| Seismic refraction profiles were carried out in 1983 and 1987 throughout the Kerguelen Isles (southern Indian Ocean, Terres Australes and Antarctiques Francaises, TAAF) and thereafter at sea on the Kerguelen-Heard Plateau during the MD66/KeOBS cruise in 1991. These profiles substantiate the existence of oceanic-type crust beneath the Kerguelen-Heard Plateau stretching from 46 degrees S to 55 degrees S, including the archipelago. Seismic velocities within both structures are in the range of those encountered in 'standard' oceanic crust. However, the Kerguelen Isles and the Kerguelen-Heard Plateau differ strikingly in their velocity-depth structure. Unlike the Kerguelen Isles, the thickening of the crust below the Kerguelen-Heard Plateau is caused by a 17 km... |
| Tipo: Text |
Palavras-chave: Hotspot; Kerguelen; Lower crust; Oceanic islands; Oceanic plateau; Underplating. |
| Ano: 1995 |
URL: https://archimer.ifremer.fr/doc/00297/40791/39809.pdf |
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| Tada, Noriko; Tarits, Pascal; Baba, Kiyoshi; Utada, Hisashi; Kasaya, Takafumi; Suetsugu, Daisuke. |
| We have conducted a seafloor magnetotelluric survey that images, for the first time, three-dimensional electrical conductivity structure in the upper mantle beneath the Society hotspot. A striking feature in our model is a high-conductivity anomaly a few hundred kilometers in diameter, which is continuous from the lowest part of the upper mantle to a depth of approximately 50km below sea level. Using theoretical and experimental results from mineral physics, we interpret the high-conductivity anomaly as evidence of the melt fraction up to 2.2vol.%, which is robust regardless of assumed temperature, and the existence of carbonated silicate melt beneath the hotspot. Our results suggest that the Society hotspot is a pathway for ascending volatiles from the... |
| Tipo: Text |
Palavras-chave: Hotspot; Marine magnetotellurics; Three-dimensional inversion; Volatiles; Partial melt. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00638/75054/75611.pdf |
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| Hekinian, Roger; Cheminee, J; Dubois, J; Stoffers, P; Scott, S; Guivel, C; Garbe Schonberg, D; Devey, C; Bourdon, B; Lackschewitz, K; Mcmmurtry, G; Le Drezen, Eliane. |
| Multibeam bathymetry and bottom imaging (Simrad EM12D) studies on an area of about 9500 km(2) were conducted over the Pitcairn hotspot near 25degrees10'S, 129degrees 20'W In addition, 15 dives with the Nautile submersible enabled us to obtain ground-true observations and to sample volcanic structures on the ancient ocean crust of the Farallon Plate at 3500-4300 in depths. More than 100 submarine volcanoes overprint the ancient crust and are divided according to their size into large ( > 2000 in in height), intermediate (500-2000 in high) and small ( < 500 in high) edifices. The interpretation of seafloor backscatter imagery accompanied by submersible observations and sampling enabled us to infer that the total volume of submarine lava erupted during... |
| Tipo: Text |
Palavras-chave: Petrology; Volcanic sequences; Morphology; Volcanism; Hotspot. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-784.pdf |
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| ARROYO,MARY T. K; MARTICORENA,CLODOMIRO; MATTHEI,OSCAR; MUÑOZ,MÉLICA; PLISCOFF,PATRICIO. |
| Santuario de la Naturaleza Yerba Loca (SN Yerba Loca), Metropolitan Region (MR), 33º S, Chile is analyzed for its conservation value and efficiency in protecting native vascular plants in a regional context. The reserve's flora of 500 species and subtaxa was evaluated for species richness, endemism, range size and marginally distributed taxa, using species-area analysis, and tendencies in the floras of the MR (1.434 species and subtaxa) and MR-Fifth regions (1,841 species and subtaxa) to set the regional pattern. The reserve (0.7 % of MR land area and 0.3 % MR-Fifth land area) contains 34 % of the MR and 27% of the MR-Fifth floras, and around 16-17 % of the mediterranean-climate area (regions IV-VIII) flora of central Chile. Veech's Relative Richness Index... |
| Tipo: Journal article |
Palavras-chave: Conservation efficiency; Endemism; Hotspot; Protected area; Mediterranean flora; Species richness. |
| Ano: 2002 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2002000400012 |
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| Gasper,André Luís de; Eisenlohr,Pedro V.; Salino,Alexandre. |
| ABSTRACT Estimating species richness with herbarium data and new collections allows us to understand the distribution of diversity. We investigated the accuracy of lycophyte and fern sampling along a vegetation gradient in the subtropical Atlantic Forest in southern Brazil. We compiled lycophyte and fern collection metadata and estimated species richness and assessed sampling accuracy for sixty 50 x 50 km units using ACE, Chao 1, Chao 2, Jackknife 1 and Jackknife 2 estimators. We compiled data for 12,779 fern specimens of 441 species, 67 of which were sampled in only one unit (singletons) and 35 in two units (duplicates). Of the 60 units examined, only 11 had observed values that were above 70% of their estimated values, and 14 had observed levels between... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Botanical collections; Estimators; Hotspot; Pteridophyte; Southern Brazil; Species richness estimates. |
| Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062016000200166 |
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| Ostroski,Piera; Saiter,Felipe Zamborlini; Amorim,André Márcio; Fiaschi,Pedro. |
| Abstract: The forest along the coast of Bahia state, in northeastern Brazil, has been acknowledged as an area of endemism for several groups of organisms. The first study concerning endemic angiosperm species in this region, through which 395 taxa were registered, was conducted 15 years ago. However, this number is probably underrated. In this article, we present an updated checklist of angiosperm taxa in Bahia Coastal Forests (BCF) based on geographic distribution data available from the Brazilian Plant List (Flora do Brasil 2020). The records were checked in herbaria, recent taxonomic literature, and, when necessary, reviewed by experts. The final checklist consists of 547 taxa endemic to BCF, distributed in 69 families, with seven endemic genera:... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Atlantic Forest; Checklist; Conservation; Endemism; Hotspot. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032018000400205 |
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| Almeida-Gomes,Mauricio; Siqueira,Carla Costa; Borges-Júnior,Vitor Nelson Teixeira; Vrcibradic,Davor; Ardenghi Fusinatto,Luciana; Frederico Duarte Rocha,Carlos. |
| Species inventories are useful tools to improve conservation strategies, especially in highly threatened biomes such as the Brazilian Atlantic Forest. Here we present a species list of amphibians and reptiles for the Reserva Ecológica de Guapiaçu (REGUA), a forest reserve located in the central portion of Rio de Janeiro state, Brazil. The list results from an extensive sampling effort that lasted ten years. A total of 73 amphibian (of which ten are endemic to the state) and 37 reptile species was recorded from the area. Five amphibian species are presently categorized by the IUCN as “data-deficient”, two as “near threatened” and one as “endangered”, whereas one reptile species is categorized as “vulnerable”. Our results showed that REGUA harbors about... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amphibians; Atlantic Forest; Conservation; Hotspot; Reptiles. |
| Ano: 2014 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032014000300201 |
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| Registros recuperados: 14 | |
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