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- Cartografia e caraterização composicional cerâmica de argilas comuns da região de Torres Vedras - BombarralPublication . Lisboa, Jose; Sardinha, Rui; Oliveira, Álvaro; Carvalho, J. F.
- Contribuição para o conhecimento das argilas da Bobonaro Scaly Clay e suas potencialidades na região de Venilale, Timor LestePublication . Lisboa, Jose; Carvalho, Jorge; Oliveira, Álvaro; Carvalho, C.; Grade, JoséEfectuou-se o levantamento geológico de uma área de afloramento da formação Bobonaro Scaly Clay (Miocénico médio) em Venilale. A mineralogia das amostras revelou argilas constituídas por ilite, caulinite, quartzo e esmectite, por ordem decrescente de teores; em percentagem acessória ocorrem feldspato potássico, plagioclase, gesso e hematite. Não existem variações significativas na composição mineralógica das amostras. A natureza essencialmente es,ectítica destas argilas, referida noutros trabalhos, não se confirmou. A possibilidade de aplicação destas argilas em cerâmica estrutural è condicionada pela adição de areia, devido ao excessivo teor de esmectites. Considerando correcções várias ao cálculo de recursos, admite-se que estes deverão rondar os 9.000.000 m3, na área cartografada.
- Typological classification of clayey raw materials for ceramics manufacture, in the Tábua region (central Portugal)Publication . Lisboa, Jose; Carvalho, Jorge; Cunha, Pedro Proença e; Oliveira, ÁlvaroMapping of clay resources in the Cenozoic deposits of the Tábua region (central Portugal) has been carried out, together with the chemical, mineralogical and technological characterization of seventeen clay samples. The study was undertaken to relate the lithostratigraphic units and the typology of raw materials with regard to the manufacture of ceramics. The sedimentary succession comprises two units with different suitability for the manufacture of ceramics: an upper unit, with clays that present technological restrictions; and a lower unit with a much greater potential. A small set of parameters has been identified which differentiate the typological units. These parameters allow a realistic estimation to be made of the ceramic properties of any clay layer sampled in the study area. It is anticipated that with minor field work and sampling, the typological column can also be used in adjacent areas.
- Argilas de Timor Leste : contribuição para o seu conhecimentoPublication . Oliveira, Álvaro; Lisboa, Jose; Carvalho, C.; Grade, José; Carvalho, Jorge
- Estudos dos depósitos lutíticos da orla ocidental: matérias-primas mineraisPublication . Oliveira, Álvaro
- Significado tectónico dos depósitos pliocénicos e plio-plistocénicos de Águeda-AnadiaPublication . Barra, António; Oliveira, Álvaro; Gomes, Alberto; Grade, José; Barbosa, Bernardo
- Patterns of rare earth and other trace elements in Paleogene and Miocene clayey sediments from the Mondego platform (Central Portugal)Publication . Lisboa, Jose; de Oliveira, Daniel Pipa Soares; Rocha, Fernando; Oliveira, Álvaro; Carvalho, JoãoIn the present study the origin of clay deposits occurring in an inland platform, in central Portugal, was investigated by their mineralogical and chemical composition. The clay deposits, exploited for ceramic industry are composed of silt-clay facies, the Monteira Member and the Arroça Member, which are assigned to the Coja Formation (Paleogene) and the Campelo Formation (Miocene), respectively. These clayey facies show almost compositional homogeneity, especially concerning texture. The mineralogical composition of the Monteira Member displays slightly higher content in smectite and interstratified clay minerals, which is supported by the chemical composition of samples analyzed. Both members present similar REE patterns, displaying an intense weathering record and little variation in the source area composition. Minor element geochemistry suggests low content in heavy minerals and transition metals. REE patterns and ratios of geochemical parameters support the dominant metasedimentary provenance, with a granite source contribution and also mature recycled sediments of continental origin. The study results’ suggest that the clays of these two members have the same source in terms of lithology and recycled sediments from the Hesperian massif. During the deposition of the Arroça Member, a major remobilization of the Monteira Member is suggested, explaining the geochemical similarity of both facies.
- Cartografia e caracterização tipológica de argilas comuns na região de Tábua (Portugal)Publication . Lisboa, Jose; Carvalho, Jorge; Oliveira, Álvaro