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Geological mineral exploration tools in the Arctic near Loki's Castle, 74 degre...
Barriga, Fernando; Fonseca, Rita; Dias, Ágata; Cruz, Inês; Carvalho, Carlos; Relvas, Jorge; Pederson, RolfDiscovery of the Loki’s Castle hydrothermal vent field (2008) was a great surprise, given its size and vigour of hydrothermal discharge. Several characteristics, including the fauna, separate it from either Atlantic or Pacific-type hydrothermal sites. Concerning size and grades, data are insufficient, but it appears so far that Loki’s Castle is a very large system, about 200 m in diameter. The metal contents (i...
Trollveggen Vent Field: Mineralogy and geochemistry of chimneys and deposits, a...
Dias, Ágata; Cruz, Inês; Fonseca, Rita; Barriga, Fernando; Pederson, RolfThe Jan Mayen vent fields were discovered in the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. They comprise two main active areas: (1) Soria Moria and (2) Gallionella Garden & Trollveggen. The Trollveggen vent field is located at depths of 700-750 m. Venting takes place mainly through white smoker chimneys with fluid temperatures reaching up to 260-270°C. Here we...
Loki’s Castle Arctic Vents and Host Sediments: Mineralogy and Geochemistry.
Cruz, Inês; Dias, Ágata; Carvalho, Carlos; Barriga, Fernando; Relvas, Jorge; Fonseca, Rita; Pederson, RolfLoki’s Castle hydrothermal field is located in the Arctic Ocean, in the bend between the South Knipovich Ridge and the Mohns Ridge, at ≈74ºN. The results presented here are from samples collected with the ROV Bathysaurus XL and consist of chimney fragments and seafloor sediments from the vicinities. The studies consist of a petrographic description, X- ray diffraction analysis, chemical analyses under the elect...
Mineralogy and Geochemistry in the Arctic crust near Loki's Castle, 74 degrees ...
Barriga, Fernando; Fonseca, Rita; Dias, Ágata; Cruz, Inês; Carvalho, Carlos; Relvas, Jorge; Pederson, RolfThe Loki’s Castle hydrothermal vent field is composed of several active, over 10 m tall chimneys, producing up to 320ºC fluid. The main sulfides in chimneys are sphalerite, pyrite and pyrrhothite, with generally lesser chalcopyrite. Alteration products collected adjacent to chimneys contain much anhydrite, gypsum and talc. Quartz, anhydrite, gypsum and barite are also present, and locally abundant. Rhythmically...
Custo amortizado e imparidade
Silva, Eduardo Sá e; Cruz, InêsInstrumentos Financeiros: Custo Amortizado e Imparidade (nova proposta) • A aplicação actual do custo amortizado e da imparidade aos instrumentos financeiros detidos pela Banca • Substituição da IAS39 (Norma Internacional de Contabilidade 39: reconhecimento e mensuração) pela IFRS 9 Instrumentos Financeiros • Lista de quadros • Resumo da IAS39 (retirado do site do IASB), em inglês • Material de apoio. ; Esta o...
Multi-stage evolution of a sub-aerial volcanic ridge over the last 1.3 Myr: S. ...
Hildenbrand, Anthony; Madureira, Pedro; Marques, Fernando; Cruz, Inês; Henry, Bernard; Silva, PedroNew K/Ar dating and geochemical analyses have been carried out on the WNW-ESE elongated oceanic island of S. Jorge (central Azores) to reconstruct the volcanic evolution of a linear ridge developed close to the triple junction between the American, the Eurasian and the Nubian lithospheric plates. We show that S. Jorge sub-aerial edification encompasses the last 1.3 Myr, a time interval far much longer than prev...
Multi-stage evolution of a sub-aerial volcanic ridge over the last 1.3 Myr: S. ...
Hildenbrand, Anthony; Madureira, Pedro; Marques, Fernando; Cruz, Inês; Henry, Bernard; Silva, PedroNew K/Ar dating and geochemical analyses have been carried out on the WNW–ESE elongated oceanic island of S. Jorge to reconstruct the volcanic evolution of a linear ridge developed close to the Azores triple junction. We show that S. Jorge sub-aerial construction encompasses the last 1.3 Myr, a time interval far much longer than previously reported. The early development of the ridge involved a sub-aerial build...
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