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Álvaro Oliveira

Bio: Álvaro Oliveira is an academic researcher. The author has contributed to research in topics: Sedimentary rock & Downwelling. The author has an hindex of 8, co-authored 19 publications receiving 670 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a program of observations carried out on the northern Portuguese shelf and slope, between July 1996 and June 1999, was used to characterise the main physical processes of the winter regime.

147 citations

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TL;DR: In this article, the distributions of clay mineral in the top layer of the sedimentary cover are shown to be related to their continental sources, but also reflect the influences of winter storms and longshore currents in determining the pathways of sediment transport.

138 citations

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TL;DR: In this article, the authors describe the mechanisms controlling the deposition of the fine-grained sediment depositions and the processes that result in resuspension processes on the Galicia-Minho Shelf.

103 citations

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TL;DR: In this paper, Dias et al. collected 31 box-core samples from the mud-patches of the Galician and North-Portuguese shelf and measured the particulate organic carbon (Corg) content.

90 citations

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TL;DR: In this paper, the authors examined the impact of the dynamic processes in the lower water column, particularly on the Douro Mud Patch (DMP), on the offshore export of fine sediments.

90 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, a comparative exploration of the biogeographical characteristics of different sub-regions comprising the Canary Current upwelling ecosystem (CanC) is presented, and it is shown that variability in coastline configuration, shelf width, coastal upwell, nutrient fertilization, productivity, or retentive vs. dispersive physical mechanisms may help explain subregional differences in fish distributions and abundances in the CanC.

308 citations

Journal ArticleDOI
TL;DR: In this paper, the mesoscale physical processes recognized in the Western Iberia Ecosystem, complementing earlier reviews dedicated to larger scales, have been investigated, and the authors support the idea that these processes, superimposed on larger scale variability, are the major factor controlling the ecosystem functioning in the region.

286 citations

Journal ArticleDOI
01 Apr 2005
TL;DR: An overview of the winter circulation and upper ocean structure offshore of Western Iberia is presented in this article, where the focus is on winter slope currents, fronts and mesoscale eddies, as well as the connection of these local features to the large-scale circulation of the region.
Abstract: An overview of the winter circulation and upper ocean structure offshore of Western Iberia is presented. The focus is on winter slope currents, fronts and mesoscale eddies, as well as on the connection of these local features to the large-scale circulation of the region. Satellite sea surface temperature; sea surface elevation data from altimetry; cross-shore and meridional hydrological surveys and current meter observations, mainly obtained during winter periods, are used to illustrate features of the winter upper ocean structure and of the generation and evolution of the Iberia Poleward Current. A schematic/hypothetical model of winter upper ocean circulation on the scale of the Western Iberian Basin is given which attempts to systematize and resolve certain ambiguities in the existing circulation schemes and in the concepts and terminology used to describe observed features in the area.

278 citations

Journal ArticleDOI
TL;DR: In this article, a comparison between modern terrestrial and marine pollen signals in and off western Iberia shows that marine pollen assemblages give an integrated image of the regional vegetation colonising the adjacent continent.

241 citations

Journal ArticleDOI
01 Mar 2015
TL;DR: In this article, the provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico (~1089-1785m water depth) were studied for mineralogy, major, trace and rare earth element geochemistry.
Abstract: The aim of this work is to constrain the provenance and depositional history of continental slope sediments in the Southwestern Gulf of Mexico (~1089–1785 m water depth). To achieve this, 10 piston sediment cores (~5–5.5 m long) were studied for mineralogy, major, trace and rare earth element geochemistry. Samples were analyzed at three core sections, i.e. upper (0–1 cm), middle (30–31 cm) and lower (~300–391 cm). The textural study reveals that the core sediments are characterized by silt and clay fractions. Radiocarbon dating of sediments for the cores at different levels indicated a maximum of ~28,000 year BP. Sediments were classified as shale. The chemical index of alteration (CIA) values for the upper, middle, and lower sections revealed moderate weathering in the source region. The index of chemical maturity (ICV) and SiO 2 /Al 2 O 3 ratio indicated low compositional maturity for the core sediments. A statistically significant correlation observed between total rare earth elements (∑REE) versus Al 2 O 3 and Zr indicated that REE are mainly housed in detrital minerals. The North American Shale Composite (NASC) normalized REE patterns, trace element concentrations such as Cr, Ni and V, and the comparison of REE concentrations in sediments and source rocks indicated that the study area received sediments from rocks intermediate between felsic and mafic composition. The enrichment factor (EF) results indicated that the Cd and Zn contents of the upper section sediments were influenced by an anthropogenic source. The trace element ratios and authigenic U content of the core sediments indicated the existence of an oxic depositional environment.

198 citations