8 research outputs found
Discontinuity characterization and instability situations of an ornamental limestone quarry in Valinho de Fátima
Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)Apresenta-se o estudo das descontinuidades e das potenciais situações de instabilidade de uma
pedreira de calcário ornamental que se localiza nas imediações de Valinho de Fátima (freguesia de
Fátima). Definiram-se trĂŞs famĂlias principais de descontinuidades, bem como as suas principais
caracterĂsticas: orientação, espaçamento, persistĂŞncia, abertura, material de preenchimento, rugosidade,
presença da água, Ăndice de diaclasamento volumĂ©trico e ângulo de atrito. AtravĂ©s da análise cinemática,
em que utilizou o método de Markland, identificaram-se situações de instabilidade de rotura em cunha.This article presents the study of discontinuities and potential slope instability of an
ornamental limestone quarry located in Valinho de Fátima. Three joints sets were defined, as well as its
characteristics such as: orientation, spacing, persistence, aperture, filling, roughness, percolation,
volumetric joint count and friction angle. A kinematic analysis, based on Markland’s method was carried
out, which allowed the identification of wedge failures occurrences
Discontinuity characterization and instability situations of an ornamental limestone quarry in Valinho de Fátima
Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)Apresenta-se o estudo das descontinuidades e das potenciais situações de instabilidade de uma
pedreira de calcário ornamental que se localiza nas imediações de Valinho de Fátima (freguesia de
Fátima). Definiram-se trĂŞs famĂlias principais de descontinuidades, bem como as suas principais
caracterĂsticas: orientação, espaçamento, persistĂŞncia, abertura, material de preenchimento, rugosidade,
presença da água, Ăndice de diaclasamento volumĂ©trico e ângulo de atrito. AtravĂ©s da análise cinemática,
em que utilizou o método de Markland, identificaram-se situações de instabilidade de rotura em cunha.This article presents the study of discontinuities and potential slope instability of an
ornamental limestone quarry located in Valinho de Fátima. Three joints sets were defined, as well as its
characteristics such as: orientation, spacing, persistence, aperture, filling, roughness, percolation,
volumetric joint count and friction angle. A kinematic analysis, based on Markland’s method was carried
out, which allowed the identification of wedge failures occurrences
Antimony quartz and antimony-gold quartz veins from northern Portugal
Antimony- and Pb-Sb-quartz veins from the Bragança district, Portugal, are mainly hosted by Silurian phyllites. Antimony-Au-quartz veins from the Dúrico-Beirã region are mainly hosted by a Cambrian schist-metagraywacke complex, as well as Ordovician phyllites and quartzites. The deposits were mostly exploited in the late 19th Century. Mineralogical characteristics and chemical compositions of individual ore minerals are similar in the two areas. First and second generations of arsenopyrite precipitated at 390 and 300 °C, respectively. Berthierite and stibnite are the most abundant Sb-bearing minerals and precipitated between 225 and 128 °C, native antimony at < 200 °C. Drastic fluid cooling is the main cause of mineral precipitation. The Pb isotope compositions of stibnite suggest a homogeneous crustal source of lead, from the metasedimentary sequences, for Sb, Pb-Sb and Sb-Au deposits in both areas, which is consistent with the findings for comparable mineralizations elsewhere in Europe. Remobilization of Pb is related to Variscan metamorphism and deformation.http://www.sciencedirect.com/science/article/B6V90-4SS1KKX-1/1/0011e7cdc8549fdf26d7f4bc628b3bb