Early Diagenesis of Lower Pliensbachian Sediments from the Algarve Basin (Portugal): Characterisation and Relation with Tectonic Evolution

The Lower Jurassic (Lower Pliensbachian) sedimentary record of the western end of the Algarve Basin (Portugal) is made of decimetric thick layers of limestone and dolomitized limestone with chert nodules and inter-layered chert beds. Most of the observable lithologies are the product of an early diagenetic evolution and the original lithological content of the formation included limestones, marls and calciclastic limestones. In this area the sedimentation was controlled by the tectonic stretching responsible for the evolution of the Algarve Basin, as well as by short-lived events of tectonic inversion. These episodes of tectonic inversion were responsible for the some uplift with the development of unconformities, sometimes with erosional surfaces separating the different sedimentary packages. The early diagenesis affecting the Lower Pliensbachian sediments is characterized by: (i) a mechanical event controlled by the syn-sedimentary stretching, responsible for the development of calciclastic dikes and nodules alignements; (ii) the substitution of the carbonates from the most permeable calciclastic limestone layers by silica, leading to the development of the observed cherts; (iii) the dolomitization of the preserved limestones; and (iv) the infilling of joints and normal fault planes by silica-rich fluids leading to the development of quartz veins. This set of diagenetic transformations took place before the Upper Pliensbachian which lacks the evidences of their occurrence. The whole-rock geochemical data of the carbonate and siliceous sediments of the Lower Pliensbachian revealed some affinities between both lithological types namely the lack of Ce anomalies and the presence of La anomalies in the REE patterns of all samples. The similarities between the carbonate lithologies which diagenetic evolution is marked by the replacement of calcite by dolomite and the siliceous sediments derived from the replacement of calcite by quartz establish a chemical connection between the two sets of rocks. This connection can be interpreted as a testimony of a common primary precursor for both lithological groups or as a testimony of a common character of the diagenetic fluids which interacted with the original sediments. The dolomitization changed the Sr isotopic signature increasing the 87Sr/86Sr ratios from 0.7073 in the unchanged limestone to a maximum value of 0.7113 in the dolomitized samples. This strong increase together with the 13C/12C and 18O/16O values support an external origin for the dolomitizing fluids. A possible origin for the diagenesis is meteoric water coming into the basin after weathering the country rocks. The hydrologic regime in the basin certainly underwent important changes during the uplift events associated to the mentioned tectonic inversion episodes and uplift allowing for input of water from land

Early Diagenesis of Lower Pliensbachian Sediments from the Algarve Basin (Portugal): Characterisation and Relation with Tectonic Evolution

The Lower Jurassic (Lower Pliensbachian) sedimentary record of the western end of the Algarve Basin (Portugal) is made of decimetric thick layers of limestone and dolomitized limestone with chert nodules and inter-layered chert beds. Most of the observable lithologies are the product of an early diagenetic evolution and the original lithological content of the formation included limestones, marls and calciclastic limestones. In this area the sedimentation was controlled by the tectonic stretching responsible for the evolution of the Algarve Basin, as well as by short-lived events of tectonic inversion. These episodes of tectonic inversion were responsible for the some uplift with the development of unconformities, sometimes with erosional surfaces separating the different sedimentary packages. The early diagenesis affecting the Lower Pliensbachian sediments is characterized by: (i) a mechanical event controlled by the syn-sedimentary stretching, responsible for the development of calciclastic dikes and nodules alignements; (ii) the substitution of the carbonates from the most permeable calciclastic limestone layers by silica, leading to the development of the observed cherts; (iii) the dolomitization of the preserved limestones; and (iv) the infilling of joints and normal fault planes by silica-rich fluids leading to the development of quartz veins. This set of diagenetic transformations took place before the Upper Pliensbachian which lacks the evidences of their occurrence. The whole-rock geochemical data of the carbonate and siliceous sediments of the Lower Pliensbachian revealed some affinities between both lithological types namely the lack of Ce anomalies and the presence of La anomalies in the REE patterns of all samples. The similarities between the carbonate lithologies which diagenetic evolution is marked by the replacement of calcite by dolomite and the siliceous sediments derived from the replacement of calcite by quartz establish a chemical connection between the two sets of rocks. This connection can be interpreted as a testimony of a common primary precursor for both lithological groups or as a testimony of a common character of the diagenetic fluids which interacted with the original sediments. The dolomitization changed the Sr isotopic signature increasing the 87Sr/86Sr ratios from 0.7073 in the unchanged limestone to a maximum value of 0.7113 in the dolomitized samples. This strong increase together with the 13C/12C and 18O/16O values support an external origin for the dolomitizing fluids. A possible origin for the diagenesis is meteoric water coming into the basin after weathering the country rocks. The hydrologic regime in the basin certainly underwent important changes during the uplift events associated to the mentioned tectonic inversion episodes and uplift allowing for input of water from land

Polémica suscitada pelos diferentes intervenientes no projecto de norma ‘Agricultura’

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Marco Martins: gosto de trabalhar o orçamento para decidir onde gasto o dinheiro

O projecto “Principais tendências no cinema português contemporâneo” nasceu no Departamento de Cinema da ESTC, com o objectivo de desenvolver investigação especializada a partir de um núcleo formado por alunos da Licenciatura em Cinema e do Mestrado em Desenvolvimento de Projecto Cinematográfico, a que se juntaram professores-investigadores membros do CIAC e convidados. O que agora se divulga corresponde a dois anos e meio de trabalho desenvolvido pela equipa de investigação, entre Abril de 2009 e Novembro de 2011. Dada a forma que ele foi adquirindo, preferimos renomeá-lo, para efeitos de divulgação, “Novas & velhas tendências no cinema português contemporâneo”.QUAIS SÃO, hoje, as principais características do desenvolvimento de projectos para cinema em Portugal? O que pensam realizadores cinematográficos, produtores, distribuidores e exibidores sobre o cinema português? Que conclusões tirar das suas opiniões, relatos de experiências e análises da situação contemporânea? Que novas tendências surgiram no cinema português, nos primeiros anos do séc. XXI?Fundação para a Ciência e Tecnologia, Centro de Investigação em Artes e Comunicação, Instituto do Cinema e do Audiovisual, Ministério da Cultura, Escola Superior de Teatro e Cinema

Maus tratos e rendimento académico num meio sócio-económico desfavorecido

O reconhecimento de que a ocorrência de maus tratos da infância não é rara e que o seu impacto é significativo quer durante a própria infância, quer ao longo da vida, tem estimulado um conjunto de investigações que procura avaliar os factores de risco para esta problemática e os efeitos que tem nas suas vítimas. Neste artigo é apresentado um estudo sobre a relação entre maus tratos e aproveitamento escolar, realizado num meio socio-económico desfavorecido. Os resultados indicam que a prevalência de maltrato é elevada e que as crianças que relatam cuidados menos adequados são aquelas que têm pior rendimento escolar

Recursos Educativos na Internet

A Internet é, hoje em dia, uma realidade inquestionável que tem vindo a provocar mudanças rápidas e significativas em quase todos os sectores da nossa sociedade. De facto, a possibilidade de aceder e trocar informação de uma forma rápida e global tem vindo a provocar mudanças significativas na forma como vivemos e como trabalhamos

Within the dialog between anthropology and museums

This article presents the work conducted at the Reference Center for Brazilian Football (São Paulo), focusing on methodological aspects of information gathering and the transfer of data to a computerized database. By using an ethnographic method to discover archives and register memories and references related to football practices, the project allows reflecting on the limits and potential of ethnography for the museological work of preservation and promotion of archives

Career planning, behaviour and academic performance in basic education

Career planning stimulates personal competence and coping with career and future. We analyse the simultaneous relationship between career planning and academic behaviour and performance. Participants were 446 students from the 5th year (231, 52.2% boys), aged nine to 13 years old (M = 10.23, SD = 0.49). A demographic questionnaire and the planning subscale of the Childhood Career Development Scale were used. Results evidenced two different career profiles: the constructive, with higher planning and positive outcomes in academic behaviour and performance; the vulnerable, with lower planning, behavioural problems, more learning difficulties, and school retention. Keywords: career development, childhood, career planning, academic performance.O planeamento de carreira estimula sentimentos de competência pessoal que habilitam a lidar com a carreira e o futuro. Analisa-se a relação simultânea entre planeamento da carreira e comportamento e desempenho académico. Participaram 442 alunos do 5º ano (231, 52.2% rapazes), com idades entre nove e 13 anos (M = 10.23, DP = 0.49). Utilizou-se um questionário de identificação e a subescala planeamento da Childhood Career Development Scale. Os resultados evidenciam dois perfis de carreira: o construtivo, com mais planeamento, comportamento e resultados académicos positivos; o vulnerável, com o planeamento mais baixo, problemas comportamentais, mais dificuldades na aprendizagem e retenções. Palabras chave: desenvolvimento de carreira, infância, planeamento da carreira, desempenho académico.O planeamento de carreira estimula sentimentos de competência pessoal que habilitam a lidar com a carreira e o futuro. Analisa-se a relação simultânea entre planeamento da carreira e comportamento e desempenho académico. Participaram 442 alunos do 5º ano (231, 52.2% rapazes), com idades entre nove e 13 anos (M = 10.23, DP = 0.49). Utilizou-se um questionário de identificação e a subescala planeamento da Childhood Career Development Scale. Os resultados evidenciam dois perfis de carreira: o construtivo, com mais planeamento, comportamento e resultados académicos positivos; o vulnerável, com o planeamento mais baixo, problemas comportamentais, mais dificuldades na aprendizagem e retenções. Palabras chave: desenvolvimento de carreira, infância, planeamento da carreira, desempenho académico.info:eu-repo/semantics/publishedVersio