Hot spot volcanic tracks and their implications for south American plate motion, Campos basin (Rio de Janeiro state), Brazil

The offshore area northern off Rio de Janeiro State (fig. 1a) is a big oil production region known as Campos basin. In some locations oil is being exploited in water depths of A00 meters, among the largest in the world and new promising fields shall be exploited above 1000 meters. The design and operation of structures and other oceanic systems for such depths is being a big challenge for ocean engineers and the knowledge of environmental conditions is of paramount importance. Wave data is still scarce in the area mainly that concerned with directional spectra.

Download Full-text

QUÍMICA MINERAL E IDADES U-Pb DE MONAZITAS DE PLACERS MARINHOSDA REGIÃO NORTE FLUMINENSE

Revista Geonomos ◽

10.18285/geonomos.v2i20.244 ◽

2012 ◽

Author(s):

Elizabeth Kerpe Oliveira ◽

Bernhard Bühn ◽

José Marques Correia Neves ◽

Alexandre de Oliveira Chaves ◽

Mário Luiz de Sá Carneiro Chaves

Keyword(s):

Rio De Janeiro ◽

Regional Metamorphism ◽

Mineral Chemistry ◽

Campos Basin ◽

Icp Ms ◽

Placer Deposits ◽

Homogeneous Composition ◽

Janeiro State ◽

Geological Context

Este trabalho abrange o estudo de química mineral e geocronologia U-Pb de grãos de monazita, composicionalmentehomogêneos, provenientes de várias jazidas explotadas pelas Indústrias Nucleares do Brasil (INB) em placers marinhos da região de Buena,litoral norte fluminense. A área está localizada na região da Bacia de Campos e, geologicamente, pertence à Província TectônicaMantiqueira, que representa um sistema orogênico neoproterozóico desenvolvido na borda sudeste do Cráton São Francisco. As idades UPbobtidas por LA-ICP-MS abrangem um intervalo entre 486 Ma e 579 Ma, sendo que as idades mais jovens são de grãos de monazitas ricosem cério. Por outro lado, as idades mais antigas correspondem a grãos de monazitas com tendência à composição cheralítica, nos quaisocorre um enriquecimento principalmente em CaO e ThO2. A comparação dessas idades com informações geológicas regionais permiteinferir as suítes G2 (granitos granada-biotita gnaisse foliado) e G3 (leucogranitos, não deformados, encaixados em G2) como rochas-fonteda população de monazita mais antiga, suítes estas relacionadas com o arco sin-colisional desenvolvido simultaneamente aometamorfismo e à deformação regional Neoproterozóica. Já a população de monazita mais jovem pode ser proveniente de corposgraníticos das suítes G4 (plútons magmáticos zonados) e G5 (ballons magmáticos), representantes das fases pós-colisionais.Palavras-chave: Monazita, quimica mineral, idades U-Pb, LA-ICP-MS. ABSTRACTMINERAL CHEMISTRY AND U-Pb AGES OF MONAZITE FROM MARINE PLACERS OF THE NORTHERN RIO DE JANEIRO STATE - Thisresearch focusses on mineral chemistry and U-Pb geochronology of monazite grains of homogeneous composition, originating from severalmarine-placer deposits exploited by Indústrias Nucleares do Brasil (INB), in Buena, northern Rio de Janeiro State. Buena is located close tothe Campos Basin and related to the geological context of the Mantiqueira Tectonic Province, which represents a neoproterozoic orogenicsystem developed in the southern edge of the São Francisco Craton. Uranium-Pb ages by LA-ICP-MS fall between 486 Ma and 579 Ma.Younger ages are related to Ce-rich monazite. Older ages correspond to monazite with cheralitic signature, chiefly enriched in CaO andThO2. These ages are interpreted in the geological context of the Mantiqueira Tectonic Province as rock sources for older monazites, whichare correlated to syn-collisional arc simultaneously developed together the neoproterozoic regional metamorphism and deformation. Theyounger monazites came from granitic plutons of G4 and G5 suites, related to post-collisional phases.Keywords: Monazite, mineral chemistry, U-Pb ages, LA-ICP-MS.

Download Full-text

Two new Hyalonema species (Hyalonematidae: Amphidiscosida) from eastern and south-eastern Brazil, and further Hexactinellida (Porifera) collected from seamounts off south-eastern Brazil by the RV ‘Marion Dufresne’ MD55 expedition

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315409000253 ◽

2009 ◽

Vol 89 (6) ◽

pp. 1243-1250 ◽

Cited By ~ 8

Author(s):

Konstantin R. Tabachnick ◽

Larisa L. Menshenina ◽

Daniela A. Lopes ◽

Eduardo Hajdu

Keyword(s):

New Species ◽

Atlantic Ocean ◽

Rio De Janeiro ◽

Western Atlantic ◽

South Eastern ◽

First Finding ◽

Campos Basin ◽

Eastern Brazil ◽

Janeiro State ◽

Hexactinellid Sponges

Descriptions of hexactinellid sponges collected by the RV ‘Marion Dufresne’ MD55 expedition on the Vitória–Trindade seamounts chain (off Espírito Santo State, south-eastern Brazil) in 1987 and stored in the MNHN (Muséum National d'Histoire Naturelle in Paris) are presented. Hyalonema (Cyliconema) conqueror sp. nov. (the first finding of this subgenus in the Atlantic Ocean) and H. (Prionema) dufresnei sp. nov. (the second record of this subgenus for the Atlantic Ocean) are described as new species. The holotype of H. (C.) conqueror sp. nov. was collected with a ROV at Campos Basin (off Rio de Janeiro State, south-eastern Brazil), while the paratypes originated from Vitória–Trindade seamounts chain and off Bahía State (eastern Brazil). Other hexactinellids reported here, Farrea sp., Sarostegia aff. oculata, Aphrocallistes aff. beatrix, Dactylocalyx aff. subglobosus and Euplectella suberea were known before to be widely distributed in the Atlantic Ocean. The total number of hexactinellid sponges known from Brazil has risen to 15 and from the south-western Atlantic to 23.

Download Full-text

Evolution of the Walvis Ridge-Rio Grande Rise Hot Spot System: Implications for African and South American Plate motions over plumes

Journal of Geophysical Research Atmospheres ◽

10.1029/jb095ib11p17475 ◽

1990 ◽

Vol 95 (B11) ◽

pp. 17475 ◽

Cited By ~ 253

Author(s):

John M. O'Connor ◽

Robert A. Duncan

Keyword(s):

Hot Spot ◽

Rio Grande ◽

South American ◽

South American Plate ◽

Plate Motions ◽

Walvis Ridge

Download Full-text

Breeding review of Gray-hooded Gull Chroicocephalus cirrocephalus in Brazil with contributions on nests and egg biometry

Papéis Avulsos de Zoologia ◽

10.11606/1807-0205/2020.60.60 ◽

2020 ◽

Vol 60 ◽

pp. e20206060

Author(s):

Rodolfo Teixeira Frias ◽

Lucas Rocha Melo Porto ◽

Luciano Gomes Fischer ◽

Patrícia Luciano Mancini

Keyword(s):

Literature Review ◽

Rio De Janeiro ◽

Rio Grande ◽

South American ◽

Northern Coast ◽

Rio Grande Do Sul ◽

Online Databases ◽

Almost All ◽

First Time ◽

Janeiro State

The Gray-hooded Gull (Chroicocephalus cirrocephalus) is a seabird distributed in almost all South American countries. However, breeding information on the species in Brazil is scarce. In this study, literature review and search in online databases (WikiAves and eBird) were carried out to gather breeding information on the species in the country and nests of the Gray-hooded Gull were recorded on the northern coast of the Rio de Janeiro state. Literature review indicated breeding records in Rio Grande do Sul, Rio de Janeiro and Rio Grande do Norte states. On WikiAves, 19 records of the species with nests, eggs, chicks and breeding colonies were reported between 2009 and 2020, in Macau, Rio Grande do Norte and one adult hatching at Rio Grande do Sul. In August 2019, two nests were recorded at Ubatuba lagoon (22°09′S and 41°18′W) in the Restinga de Jurubatiba National Park, in the Quissamã municipality in Rio de Janeiro. The nests were described and monitored during five weeks. Each nest contained two eggs and was built with the grass Paspalum vaginatum. Over time, the eggs were degraded and disappeared from the nests, without signs of hatching and possible predation. This study compiles for the first time all the breeding information on the species in Brazil and contributes with data about the nests and egg biometry.

Download Full-text

Brazilian Equatorial Margin: evidences of magmatic intrusion and alteration of host rock from well data

10.5194/egusphere-egu2020-20540 ◽

2020 ◽

Author(s):

Andre Aquino da Silva ◽

Yoe Alain Reyes Perez ◽

Helenice Vital

Keyword(s):

Host Rock ◽

Plate Motion ◽

South American ◽

South American Plate ◽

Magmatic Intrusion ◽

Magmatic Rocks ◽

Fernando De Noronha ◽

Volcanic Islands ◽

Well Data ◽

Rock Alteration

<p>The mechanisms of magmatic intrusion is very complex and are commonly associated to pristine unconformities (weak spots) on the crust that ease its emplacement on the form of sills or dikes. When occurring on the Oceanic crust these weak spots may led to the formation of volcanic islands (such as Fernando de Noronha, on the Brazilian Equatorial Margin-BEM), submarine highs. Alignment of such features are related to Plate motion and the set of volcanos of Fernando de Noronha Ridge are considered a consequence of the westward motion of the South American Plate. Occurrence of magmatic rocks were found on a set of offshore wells at different depths and away of submarine highs. These magmatic emplacement suggests be related to a deep plume-fed mechanism which is the source of all sills found on the wells, as well as the volcanic highs occurring of the BEM. The lateral extents of the sills is greatly influenced by the presence of faults when preceding the intrusion, during which also occurred incorporation of parts of the host rock as xenoliths. On the well logs it is possible to observe changes on sonic slowness for the same lithotype when close to the sills, which indicates rock alteration due to the magmatic intrusion.</p>

Download Full-text