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Contribuiçao para o conhecimento geologio de Coimbra

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... Etapa I.1 -Sequências A e B Os depósitos basais de enchimento da Bacia Lusitânica constituem os designados -Grês de Silves‖, do Triásico Superior (Palain, 1976;Soares et al., 1985). São depósitos siliciclásticos de leque aluvial mediano a distal, com uma espessura total próxima de 400 metros, definindo duas sequências correspondentes ao início da configuração da bacia no Carniano (Fm Conraria) e sua re-activação no Noriano (Fm Castelo Viegas). ...
... Para o topo, aumenta a abundância de intercalações dolomíticas, passando a sedimentação predominantemente carbonática com espessura da ordem da centena de metros (Fm Coimbra, Sinemuriano) (Soares et al., 1985). Para o topo, encontram-se alguns níveis margosos com potencial gerador (Água de Madeiros) e localmente a sedimentação é calcária. ...
... Os depósitos do Triásico superior da Bacia Lusitânica, predominantemente siliciclásticos, estão organizados em três sequências maiores, bem evidentes na região de Coimbra (Palain, 1976;Soares et al., 1985;Pimentel, 2005;Pena dos Reis & Pimentel, 2006). ...
... Na figura 3 apresentam-se as correlações no interior do Grupo dos "Grés de Silves" ou Grupo de Silves (Soares & al., 1985;Rocha & al., 1987Rocha & al., , 1996 (= Grès de Silves, Choffat, 1887;Palain, 1976; = "Grés de Silves", Rocha, 1976;Rocha in Ribeiro & al., 1979;, tomando como referência o perfil de Conraria-Castelo Viegas-Pereiros, junto a Coimbra, na margem sul do Mondego (Choffat, 1894(Choffat, , 1903Palain, 1976), tratado normalmente como tipo da unidade a Soares et al., 1993e Rocha et al., 1996 Fig. 3 -Organização litostratigráfica do Grupo de Silves (Rocha et al., 1996). ...
... al., 2003) (= Camadas de Coimbra, Choffat, 1880Mouterde et al., 1972;Soares et al., 1993;= Faciès de Coimbra, Choffat, 1903) têm, no perfil combinado entre Pereiros e Lamas, dois corpos fundamentais (Choffat, 1903): na base, dolomitos e argilitos (70 a 80 m), no topo calcários dolomíticos e calcários (= Complexo com bancos mais espessos ≥110m). Soares et al. (1985) e/ou avermelhados (≥ 50 m). Para o tecto e sobre descontinuidade marcada pela ocorrência de arcose arenítica grosseira a muito grosseira esbranquiçada (0,10 m), desenvolve-se uma barra de calcários a calcários dolomíticos, amarelados a acastanhados, localmente fossilíferos. ...
... dos Calcários e Margas de Quiaios, Rocha et al., 1996) com, no Toarciano de Peniche, interposições de bancadas arcósicoareníticas (turbiditos polarizados de blocos em soerguimento a ocidente: Guéry, 1984;Wright & Wilson, 1984;Montenat et al., 1988;Duarte, 1995;Soares & Duarte, 1995;Rocha et al., 1996). A organização geral da unidade liga-se à evolução de rampa, no contexto do modelo de J. Rey (1994), com reajustes locais de blocos diferenciados Soares & Duarte, 1995), em especial para as zonas internas, mais marginais ( Soares et al., 1993), unidade da base do Grupo de Quiaios, apresenta duas características fundamentais; por um lado, a presença mais frequente de níveis margosos negros, ricos de finos fragmentos carbonosos e fósseis piritizados (na orla litoral ocorrem níveis de "xistos cartão"), por outro, a presença, ainda que variável, de margas grumosas Soares et al., 1985Soares et al., , 1993= Calcários margosos de Lemede, Soares et al., 1993;= Membro dos Calcários de Lemede, Rocha et al., 1996) Soares et al., 1985Soares et al., , 1993= Margocalcários de S. Gião, Soares et al., 1993; = Membro dos Calcários margosos de S. Gião, Rocha et al., 1996) corresponde a conjunto margocalcário, por vezes rítmico e com expressão volumétrica variável. O limite inferior coincide com a base da zona de Polymorphum, enquanto o superior, materializado na transição para um mais franco predomínio calcário, coloca-se no topo da zona de Speciosum. ...
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A Bacia Lusitaniana1 é uma bacia sedimentar que se desenvolveu na Margem Ocidental Ibérica (MOI2) durante parte do Mesozóico, e a sua dinâmica enquadra-se no contexto da fragmentação da Pangeia, mais especificamente da abertura do Atlântico Norte. Caracteriza-se como uma bacia distensiva, pertencente a uma margem continental do tipo atlântico de rift não vulcânica. Ocupa mais de 20 000 km2 na parte central da MOI, alongando-se por cerca de 200 km segundo direcção aproximada NNW-SSE e por mais de 100 km na direcção perpendicular; cerca de 2/3 aflora na área continental emersa e a restante área, encontra-se imersa, na plataforma continental (fig. 1). Trata-se da única bacia das margens do Atlântico Norte com extensa exposição superficial, pelo que tem atraído nas últimas décadas um número considerável de geólogos, especialistas de variados domínios, para a realização de trabalhos de investigação integrados em equipas nacionais e internacionais, muitos delas ligadas à indústria do petróleo. Ao longo das várias décadas de prospecção foram efectuadas cerca de 50 sondagens profundas e mais de 37 000 km de perfis sísmicos de reflexão 2D.
... de Dagorda das áreas mais centrais da Bacia. Na fig. 3 apresentam-se as correlações no interior do Grupo dos «Grés de Silves» ou Grupo de Silves (Soares et al., 1985(Soares et al., , 2010Rocha et al., 1987Rocha et al., , 1996 (= Grès de Silves, Choffat, 1887;Palain, 1976; = «Grés de Silves», Rocha, 1976;Rocha in Ribeiro et al., 1979;Soares et al., 1993), tomando como referência o perfil de Conraria-Castelo Viegas-Pereiros, junto a Coimbra, na margem sul do Mondego (Choffat, 1894(Choffat, , 1903Palain, 1976;Soares et al., 2010), tratado normalmente como tipo da unidade a norte do Tejo. ...
... No perfil tipo, a Form. de Conraria (Soares et al. in Rocha et al., 1996;Gomes, 1996;Azerêdo et al., 2003;Soares et al., 2007Soares et al., , 2010 (= Cam. de Conraria, Carvalho, 1950;Soares et al., 1985; Rocha et al., 1996;= sequências A1+A2, Palain, 1976;= Cam. de Conraria+Grés com Voltzia ribeiroi, Rocha et al., 1990) é formada, na parte inferior (=A1 in Palain, 1976) (40 m), por arcoses e subarcoses, muito grosseiras, conglomeráticas, subcompactadas a compactadas (por cimentação férrica), com estruturas oblíquas e cor vermelho tijolo, compondo canais métricos, raramente decamétricos. A unidade superior (= Grès com Voltzia ribeiroi; =A2 in Palain, 1976) corresponde a areno-pelitos e pelitos laminados, de cor vermelho violáceo e/ou cinzento, por vezes com finas estruturas oblíquas de baixo ângulo ou com estruturas onduladas (tipo flaser), bioturbadas e ricas de fragmentos carbonosos que alternam com estratos centimétricos ou decimétricos de arcosarenitos finos, micáceos e dolomitos e/ou dolomitos arenosos amarelados. ...
... A Form. de Castelo Viegas (= Cam. de Castelo Viegas, Carvalho, 1950;Soares et al., 1985;Rocha et al., 1990;= Form. de Castelo Viegas, Azerêdo et al., 2003;Soares et al., 2007) foi recentemente subdividida (Soares et al., 2010) em duas unidades, a saber, na base a Form. ...
... de Pereiros, apesar da sua grande variabilidade litológica que inclui sedimentos siliciclásticos, constitui a primeira unidade com sedimentação carbonatada do bordo oriental (e.g. Palain, 1976;Soares et al., 1985Soares et al., , 2012Azerêdo et al., 2003). A fm. de Coimbra, segundo Soares et al. (1993), é constituída por fácies dolomíticas e calcárias (ver também Soares et al., 1985;Azerêdo et al., 2003;Dimuccio, 2014;Duarte et al., 2014) (Fig. 1). ...
... Palain, 1976;Soares et al., 1985Soares et al., , 2012Azerêdo et al., 2003). A fm. de Coimbra, segundo Soares et al. (1993), é constituída por fácies dolomíticas e calcárias (ver também Soares et al., 1985;Azerêdo et al., 2003;Dimuccio, 2014;Duarte et al., 2014) (Fig. 1). ...
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This study shows preliminary data from natural gamma-ray spectrometry measurements (total counts, K, Th and U contents) carried out in outcrops of the Jurassic basal units in the Lusitanian Basin (Portugal), namely in the Pereiros and Coimbra formations. The study was developed in the northern sector of the basin, involving reference stratigraphic sections in the Castelo Viegas, Lamas, Vila Seca, Penela and Cabanas-Brenha regions. Preliminary results clearly demonstrate differentiation of the spectral range between the two units. The Pereiros formation, due its mixed and complex sedimentary and lithological character (sandstones to dolostones), shows largest variability of the spectrometric data, with average of the total counts being higher in sandstones (369 cps) and decreasing in lutites (to 328 cps) and dolostones (288 cps in the sandy dolostones and 147 cps in micritic dolostones) and maximum contents of K (6.2 %), U (8.6 ppm) and Th (25.6 ppm). Dolostones and dolomitic limestones of Coimbra formation present a decreasing vertical trend in the total counts of gamma-ray spectrometry, showing, for the same parameter, in the eastern part of the basin, an average value of 126 cps and 96 cps in the western region.
... A muddy evaporitic Hettangian/lower Sinemurian complex, detrital at the base (Pereiros and Dagorda formations; Soares et al. 2007), overlies Triassic siliciclastics. The evaporitic complex is capped by Coimbra Group carbonates (the studied succession), ranging in age from the early Sinemurian to the early Pliensbachian and recorded in two distinct subunits: the Coimbra Formation (= Coimbra beds sensu Soares et al. 1985, 2007), essentially dolomitic; and the overlying S. Miguel Formation (= S. Miguel beds sensu Soares et al. 1985, 2007), essentially dolomitic limestone and limestone. ...
... A muddy evaporitic Hettangian/lower Sinemurian complex, detrital at the base (Pereiros and Dagorda formations; Soares et al. 2007), overlies Triassic siliciclastics. The evaporitic complex is capped by Coimbra Group carbonates (the studied succession), ranging in age from the early Sinemurian to the early Pliensbachian and recorded in two distinct subunits: the Coimbra Formation (= Coimbra beds sensu Soares et al. 1985, 2007), essentially dolomitic; and the overlying S. Miguel Formation (= S. Miguel beds sensu Soares et al. 1985, 2007), essentially dolomitic limestone and limestone. ...
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An evolutionary geological/geomorphological model is proposed to explain the spatio–temporal distribution of palaeokarst affecting a Lower Jurassic shallow-marine carbonate succession (Coimbra Group; Sinemurian), cropping out in the Coimbra–Penela region (western central Portugal), in a specific morphostructural setting (dolomitic hills). Field and laboratory data allowed a detailed facies/microfacies characterization and diagenetic interpretation to be made, with special regard to the evolution of porosity. High facies/microfacies heterogeneity and contrasts in porosity, providing efficient hydraulic circulation by the development of meso- and macropermeability, significantly influenced and controlled the earliest karst-forming processes (i.e., inception), as well as the subsequent degree of karstification during the mesogenetic and telogenetic stages of the Coimbra Group.
... Our primary interest were the formations that could have been susceptible of being used as masonry, ashlars and as sculpture material. The Coimbra Beds s.l. are of Lias age (Sinemurian-lower Carixian) and are constituted of two units: the Coimbra Beds s.s. and the S. Miguel Beds [8]. The former are mainly dolostones and calcitic dolostones of primary origin while the younger unit, the S. Miguel Beds, include limestones to dolostones, marly limestones and marls. ...
... form the main part of the rock mass. Marls and Marly Limestones of Eiras (Carixian-upper Domerian) and Marls and Marly Limestones of Pedrulha (Toarcian-medium Aalenian) are other carbonate rocks occurring near Coimbra [8]. This two units are excessively argillaceous to have been used in the construction of the monument. ...
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Sumário: Sé Velha is the Old Cathedral of Coimbra and is located at mid hill-side between the University, at the summit, and down town of Coimbra. Since de beginning of its construction, in the XII century, carbonate rocks were used as original construction material, in several reconstruction works and as replacement of decayed stones. Initially local dolostones were used to built the Cathedral and the cloister and some dolostones of an earlier destroyed church were probably also used. Later on, in the XVI century, Ançã limestone was used in the construction of "Porta Especiosa" that at present shows severe destruction. In several places of the monument, the dolostone also shows severe weathering, including the in situ rock that constitutes the wall of two chapels in the cloister. A study of the original location of quarry rock sources was tried. The mapping of rock materials in the north wall was done. Some physical properties and the chemical composition of main rock types were studied.
... Both have similar depositional sequences (Palain, 1976) with the best studied being the Lusitanian Basin where most of the previous and recent work has focused (Figs. 8, 9). The two main sequences are the Gres de Silves Fm and the Dagorda Fm (Azerêdo et al., 2003;Palain, 1976;Soares et al., 1985Soares et al., , 2012Uphoff, 2005). Within these Formations, Palain (1976) defined three main units termed A, B, and C, sub-divided into A1, A2, B1, B2, C1 and C2. ...
... For Palain (1976), A1, A2, B1 were considered part of the Silves Fm and the top of B1, B2, C1 and C2 were part of the Dagorda Fm. Recent studies have attempted to update the work of Palain and divided the lithostratigraphy using similar boundaries between formations but renamed A, B, and C into the Conraria Fm (A1, A2), Castelo Viegas Fm (B1), and Pereiros Fm for B2, C1 and C2 (Rocha et al., 1990;Soares et al., 1985). The latest synthesis on the Triassic of Portugal (Azerêdo et al., 2003) further revised the stratigraphy considering the Dagorda Fm as a lateral/distal equivalent to most of the Castelo Viegas Fm and the Pereiros Fm. ...
Article
The extension-driven break-up of the Pangean Supercontinent in the present-day Central and North Atlantic domains commenced during Permo-Triassic times. Permian rift processes in this region are generally attributed to crustal collapse during the latter part of the Hercynian/Variscan orogeny, but the Triassic rifting style is more complex and the presence of a single over-riding first-order control is equivocal. Basement terrane structures and boundaries provide pre-existing zones of weakness that had significant influences on the location, timing, orientation and extent of Triassic rifting. The 201 Ma Central Atlantic Magmatic Province (CAMP), a Large Igneous Province (LIP), increased lithospheric heat flow at the end of rifting, produced uplift and doming, and also contributed to deformation and subsequent continental breakup.
... Os depósitos basais de preenchimento da Bacia Lusitânica constituem os designados Grês de Silves do Triássico Superior (Palain, 1976;Soares et al., 1985). São depósitos siliciclásticos de leque aluvial mediano a distal, com uma espessura total próxima de 400m, definindo duas sequências granodecrescentes correspondentes ao início da configuração da bacia no Carniano (Formação Conraria) e sua reactivação no Noriano (Formação Castelo Viegas). ...
... Para o topo, aumenta a abundância de intercalações dolomíticas, passando a sedimentação predominantemente carbonática com espessura da ordem de centena de metros (Formação Coimbra, Sinemuriano) (Soares et al., 1985). Nos níveis superiores, encontram-se alguns níveis margosos com potencial gerador (Formação Água de Madeiros) e, localmente, a sedimentação é calcária. ...
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The analysis of the sedimentary infill of the Lusitanian Basin allows the reconstruction of its Mesozoic evolution within a Western-European geodynamic context. That evolution may be summarized in successive tectonosedimentary steps, during which the infills record the response of the depositional systems to time and space differentiated subsidences and uplifts. The genesis of the Lusitanian Basin may be integrated in the Late Paleozoic evolution of Western Europe, with a strong influence of the Carboniferous to Permian orogenic phases of collision and ductile deformation and Permian brittle fracture. Those sutures and fractures would condition the origin and configuration of the Lusitanian Basin since the Late Triassic, in the global context of the Pangaea break-up and intra-continental troughs in Western Europe and East America. In Western Iberia, strong subsidence concentrated in asymmetric NNE-SSWtrending grabens, rapidly filled by alluvial-fan siliciclastic deposits passing to sabkha evaporite clays and salts, under arid climatic conditions. At the end of the Triassic, the basin became filled-up, due to a shallow marine tethyan ingression, with expansive onlap associated to paleogeographic coalescence of the initial troughs. The beginning of the Jurassic was marked by increased subsidence and accommodation space, not compensated by sedimentation, due to the scarcity of inputs from the surrounding areas, already largely eroded. This situation promoted a generalized marine ingression and deposition of deep-sea carbonates, rich in organic matter. A large subsiding ramp had developed by then, deepening towards W and NW and connecting itself to the tethyan European seas. Throughout the Early and Middle Jurassic, the subsidence was been attenuated, with some tectonic instability, suggesting the activity of NNE-SSW- trending basement structures, especially on the western border of the basin. A prograding and shallowing-up carbonate fill-up marks the end of this mainly marine and carbonate evolutionary step. The Callovian is marked by strong shallowing and even emersion with paleo-karstification at the borders of the basin. This event is present in all Iberia and also in the North-Atlantic American basins, possibly related to the alignment of the Central Atlantic ocean-spreading with the Western Iberian facade and the Lusitanian Basin rifting. This geodynamic re-organization promoted a regional unconformity and the re-orientation of the subsiding trough towards NNE-SSW. The initial post-unconformity deposits are mainly transitional and rich in organic matter. Intense subsidence started again in Oxfordian, with depocenter areas located to the SSW, strongly controlled by basement structures. Maximum subsidence and accommodation space, associated to the rift climax, were attained in the Lower Kimmeridgian. Uplift and intra-basinal block rotation promoted karstification and erosion of Oxfordian carbonates in the rift-shoulders. This instability may have been contemporary to important diapiric vertical movements, considering an over 1.000m thick overburden of the Triassic salt, by then. Towards the end of the Jurassic, sedimentation gradually compensated subsidence and siliciclastic turbidites prograded into the basin, passing to coastal and fluvio-deltaic deposits in Tithonian times. During the Early Cretaceous, subsidence was low and sedimentation was mainly fluvial and coastal, with alternating and mixed siliciclastics and carbonates, associated to local and global eustatic cycles. Some strong coarse-grained prograding siliciclastics mark basinal ruptures, related to the oceanspreading events at the Iberian Atlantic facade, to the SW of the Lusitanian Basin, in Berriasian (with transitional magmatic intrusions underlining this event) and Barremian times. The opening of the North Atlantic west of Iberia at Late Aptian times, introduced a strong geological record in the basin, with important uplifts (up to 2km in the northern sectors), intense erosion and coarse post-breakup conglomerates being carried towards SW. The Late Cretaceous is marked by a Cenomanian transgression, covering the basin with reefal carbonates, representing the end of the basin’s subsidence and infill. Since the Turonian, emersion became predominant in the southern sectors and thin sediments in the northern sectors register the beginning of the tectonic inversion history of the basin. Piercing of the thick Mesozoic cover by diapiric bodies and by alkaline volcanics was also attained by then. The tectonic inversion of the basin would continue and even accentuate during the Tertiary, associated to the alpine collisions. The Lusitanian Basin presents a complex evolution which should not be assigned strictly to the opening of a passive Atlantic margin. Paleozoic inheritance was crucial on the structural evolution of the basin, defi ning sub-basins and depocenter axes, magmatic events and diapiric movements. Mesozoic geodynamic location of the basin between European, African and North-American plates, as well as between the Tethys and the Atlantic oceans, also contributed to this complexity. The understanding of this mosaic, involving rapidly changing paleogeographies and tectono-sedimentary relationships, is crucial to deal with the petroleum system elements, recognized and active in the basin, and to predict its articulation in space and time.
... Os depósitos basais de preenchimento da Bacia Lusitânica constituem os designados Grês de Silves do Triássico Superior (Palain, 1976;Soares et al., 1985). São depósitos siliciclásticos de leque aluvial mediano a distal, com uma espessura total próxima de 400m, definindo duas sequências granodecrescentes correspondentes ao início da configuração da bacia no Carniano (Formação Conraria) e sua reactivação no Noriano (Formação Castelo Viegas). ...
... Para o topo, aumenta a abundância de intercalações dolomíticas, passando a sedimentação predominantemente carbonática com espessura da ordem de centena de metros (Formação Coimbra, Sinemuriano) (Soares et al., 1985). Nos níveis superiores, encontram-se alguns níveis margosos com potencial gerador (Formação Água de Madeiros) e, localmente, a sedimentação é calcária. ...
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This paper presents an interpretative synthesis of the stratigraphic analysis and geodynamic evolution of the Lusitanian Basin (Portugal) based on research works developed by the Atlantis Project team. After some methodological considerations, the West European and North Atlantic regional geodynamic framework is presented. The stratigraphic analysis has been divided into several successive steps, describing for each one its sedimentary infill, its paleogeography and its meaning in the basin's evolution. Some considerations on the basin's magmatism and diapirism are also presented. The final part deals with the analysis of the subsidence related to the basin's evolution, as well as to its uplift events. The conclusions present the main lines of the tectono-sedimentary evolution of the basin within its regional geodynamic framework. (Expanded abstract available at the end of the paper).
... A formação das Camadas de Coimbra apresenta uma idade do Jurássico Inferior e segundo Soares et al. (1985) é constituída por bancadas dolomíticas, de tonalidades acastanhadas, de caraterísticas homogéneas e/ou possuem um entrecruzado de ângulo reduzido. As Camadas de Coimbra são estrato-decrescentes e a sua espessura, na área da cidade, é de 60 ± 20 m. ...
... Os elementos mais grosseiros são constituídos por seixos de quartzo e quartzito (Soares et al., 2005). A presença de pequenos afloramentos de areias vermelhas está associada a atividade tectónica do Maciço marginal de Coimbra (Soares, 1990 Soares et al., 1985). ...
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Resumo – No presente trabalho efetua-se o estudo geológico e geotécnico relacionado com a construção do Lar integrado da Associação de Paralisia Cerebral de Coimbra (Portugal). Analisam-se, igualmente, as questões relacionadas com a edificação de uma estrutura de suporte que impeça as possíveis situações de instabilidade da plataforma de aterro a construir sobre a vertente. Neste estudo realizou-se um reconhecimento geológico e procedeu-se à recolha e análise de amostras de solos existentes, com vista à sua classificação do ponto de vista geológico e geotécnico. Com base nesta classificação foi possível obter uma previsão do comportamento geotécnico dos solos. O material rochoso foi igualmente estudado, tendo sido amostrado no decurso das campanhas de prospeção. Neste contexto, foram selecionadas amostras, posteriormente submetidas a ensaios laboratoriais. De modo a caracterizar o maciço rochoso carbonatado utilizou-se a classificação geomecânica do Rock Mass Rating (RMR). Analisaram-se várias soluções de contenção de terras, tendo em conta aspetos físicos, geológicos e geotécnicos locais. Procedeu-se ao acompanhamento das várias fases da sua implementação. Neste sentido, considera-se que a estrutura de suporte adotada é uma solução viável tendo em consideração algumas exigências relacionadas com a drenagem, cota das fundações e aplicação de tensões em alguns locais mais críticos e com acentuada carsificação. No acompanhamento das várias fases da implementação da estrutura de suporte verificou-se que algumas etapas foram suprimidas, o que pode desencadear problemas geotécnicos, a médio e a longo prazo. . Abstract – In this paper a geological and geotechnical study for the construction of a Home for the Association for Cerebral Paralysis of Coimbra (Portugal) is carried out. The study of a support structure necessary to avoid the instability of the fill platform that was constructed over the slope is also performed. A geological reconnaissance, collection and analysis of soil samples were carried out. Based on these studies, it was possible to obtain a prediction of the geotechnical behavior of the soils. The rock material was also studied, samples having been collected during the prospecting campaigns. Selected undisturbed samples were subsequently subjected to laboratory testing. The geomechanical Rock Mass Rating (RMR) classification was used to characterize the carbonated rock mass. Several solutions for the retaining earth structures were analyzed according to geological and geotechnical aspects. The various construction stages were observed. Taking into consideration drainage, dimensions and applied loads requirements, it was concluded that the
... A intrusão recorta as unidades do Jurássico inferior, constituintes do anticlinal diapírico de Soure. Contacta a N e NE, com a subunidade dos Calcários de São Miguel (sensu Soares et al., 1985) do Sinemuriano superior, que mostram inclinações importantes, cristalinidade elevada e impregnações betuminosas. Para W, S e E, contacta com as Areias Pliocénicas. ...
... Para W, S e E, contacta com as Areias Pliocénicas. A W e a S, o Pliocénico sobrepõe-se à unidade das Margas de Dagorda do Hetangiano, estratigraficamente subjacente à subunidade das Dolomias de Coimbra (sensu Soares et al., 1985), do Sinemuriano inferior. A E sobrepõe-se aos Calcários de São Miguel (Rocha et al., 1981; Rocha, 2003 e Romariz, 1960). ...
... Em contacto com o Grupo de Silves, e para oeste deste afloram, em faixa alongada e paralela à mancha do grupo anterior, um conjunto de formações essencialmente carbonatadas e dolomíticas, de idades do Liásico inferior, com espessura na ordem dos 180 m, a Formação de Coimbra. Segue-se um conjunto de unidades de calcários margosos e margas em bancadas com espessura variável que, da base para o topo, incluem a Formação de Vale das Fontes, Formação de Lemede e Formação de S. Gião, de idades desde o Carixiano ao Aaleniano inferior (Soares et al., 1985;Soares et al., 2007). ...
... O Paleogénico está representado na área pelas Formação de Bom Sucesso, de natureza arcosarenítica a subarcosarenítica e Formação de Antanhol, que apresenta na base fácies conglomeráticas e no topo níveis argilosos, encimados por níveis subarcosareníticos. As unidades quaternárias correspondem a depósitos terrígenos e arenoconglomeráticos e a aluviões (Soares et al., 1985). ...
... A morfologia traduz, em Coimbra, o "confronto dos metamorfitos prêcambricos do Maciço Hespérico, com as unidades gresosas e calcárias que, na Beira Litoral, exprimem a Orla Meso-Cenozóica Ocidental" (SOARES, MARQUES e ROCHA, 1985). ...
... Na margem direita, destacam-se as bancadas dolomíticas -as Camadas de Coimbra, onde se instalou o sítio da atual Coimbra. A evolução no Grupo processa-se de um polo mais dolomítico -Camadas de Coimbra, para um outro essencialmente calcário -Camadas de S. Miguel (SOARES, MARQUES e ROCHA, 1985), onde se instalou o núcleo mais povoado da margem esquerda da cidade. ...
... Este sílex de morfologia lenticular, de extensão lateral métrica ou em bancadas, está documentado numa faixa estreita nas proximidades da localidade de Sá, com uma estrutura heterogénea e de cor avermelhada (Figura 3, Tipo A1). Os pequenos nódulos de sílex dos perfis do Olival da Vila Santos (Coselhas -Coimbra, Figura 1, Tipo A2) e da Quinta do Monte Figueira (Camarzão-Coimbra), atribuídos por Soares de Carvalho às Camadas de Coimbra (Soares et al. 1985), devem ser estratigraficamente equivalentes dos níveis silicificados da região de Sá. Nas duas regiões, o sílex apresenta-se muito fracturado devido à tectónica. ...
... Os afloramentos atribuíveis ao Cretácico superior, localizados entre Mealhada e Condeixa-a -Nova, foram objecto de um estudo petrográfico e paleontológico que não revelou a existência de sílex em nenhum dos perfis estudados (Soares 1966, 1980, Soares et al. 1985, Callapez 1992, embora sejam conhecidos, desde há muito (Soares e Reis 1984), os níveis silicificados que ocorrem por cima do limite com a Formação de Taveiro, representativa do Campaniano-Maastrichtiano, inseridos na Formação de Bom Sucesso (Soares et al. 2007). ...
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Abstract: Geological studies developed in Portugal since the late of nineteenth century have allowed defining the main sedimentary units of the West Portuguese Meso-Cenozoic Border and their related depositional palaeoenvironments. However, despite the use of some flint layers known from this succession as stratigraphic markers and the occurrence of several forms of vein silica in paragensis with Gold and Uranium mineralisations from the Iberian Hercinian Massif, these rocks have never been systematically inventoried and studied. The study of lithic raw material sources during Prehistory has only been developed recently. These studies still lack a complete reference of the available sources and the establishment of a general characterization methodology. The mineralogical, chemical and physical evolution of flint from the original formation to its discard at the archaeological site must be taken in account, in order to evaluate the frequency of siliceous rocks collected in secondary position from detrital siliciclastic units. This paper presents the main sources of knappable siliceous rocks from Central and Northeast Portugal and three case studies addressing past foragers geographical and social issues. Resumo: Os estudos geológicos desenvolvidos em Portugal desde o último quartel do século XIX permitiram definir as principais unidades sedimentares da Orla Meso-Cenozóica Ocidental Portu-guesa e os paleoambientes deposicionais a elas associados. Todavia, apesar de alguns níveis de sílex desta sucessão serem utilizados como referência estratigráfica e de várias formas de sílica de filão estarem associadas a paragéneses com mineralizações de Urânio e Ouro do Maciço Hespéri-co, estas rochas nunca foram objecto de um inventário e estudo sistemáticos. A determinação das fontes de aprovisionamento em matérias-primas durante a Pré-história tem vindo a ser desenvol-vida apenas nos últimos anos. Estes estudos carecem ainda de um referencial completo das fontes disponíveis e do estabelecimento de uma metodologia generalizada de caracterização. É essencial ter em consideração a evolução mineralógica, química e física do sílex, desde o afloramento até ao seu abandono num solo arqueológico, para identificar e avaliar a frequência da exploração de rochas siliciosas em posição secundária, em unidades siliciclasticas.Neste artigo apresentamos as principais fontes de rochas siliciosas utilizadas para talhe em sítios arqueológicos do Centro e Nor-deste do território português e três estudos de caso, que permitem reconstituir os espaços geográ-ficos explorados e o funcionamento das sociedades do passado.
... Também as fácies argilosas do Grupo de Silves 1 (Soares et al. 1985, Rocha et al. 1987 ) e a Formação de Dagorda 2 (Rocha et al. 1996, Azerêdo et al. 2003 foram exploradas para cerâmica de construção e olaria, como sucede na área a SW de Leiria, mas a qualidade destas argilas não satisfaz geralmente, as necessidades atuais do setor cerâmico de construção. Continuam contudo, a ser localmente exploradas para olaria. ...
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Common clays are the mineral resource supplier for the building ceramics and pottery industries. These usually consist of red ceramic products, which constitute the oldest and most important ceramic sector in terms of mineral resources amount used (building ceramics) and gen-eration of revenue. In Portugal broad areas of occurrence of common clays resources are known since long ago, but its lithostratigraphic framework, characterization and registration of the ex-ploiting areas needs updating. The study of existing information, in the form of reports, publica-tions and geographical information from the Portuguese Geological Survey (National Laboratory of Energy and Geology, LNEG on the occurrences of clay and exploitation activity, yielded the follow-ing results: definition of geological formations with higher potential for occurrence of clays for building ceramics and pottery, of which those of Cretaceous and Cenozoic age prove to be the most important in resources amount (particularly for building ceramics); geographical location of known clay occurrences or potentially clay-rich formations; compositional/ceramic features of clays, and the identification of the main ceramic mining camps. The interpretation of these results allows to relate the compositional diversity and the ceramic aptitude, and to identify new suitable areas for exploitation beyond the today or recent past areas. It is also possible to trace a general trend of the mining activity in geographical terms, from the beginning of the last century and to observe its tendency to nucleate in exploitation/processing camps. Thus, there is a contribution to the knowledge in common clay resources in the country, which constitutes a tool that can be used in land use planning for sustainable management of these resources, preventing its depletion.
... A zona urbana de Coimbra situa-se no sector mais a norte da Bacia Lusitânica (Soares e Rocha, 1984), no limite entre o Maciço Hespérico, constituído por terrenos dos períodos Pré-Câmbrico e Paleozoico e os depósitos da Orla Meso-Cenozoica Ocidental, estes últimos com 225 ± 5 milhões de anos (Soares et al., 1985). Na região a SE de Coimbra, ao longo do rio Ceira, constata-se a ocorrência de rochas metamórficas constituídas por xistos com forte deformação e recristalização. ...
... The particular requirements of the species could also be responsible for the shrinking of the populations, e.g. low competition from other plants, substantial moisture, semi-shade/shade, low altitude and possibly a link to a ferric substrate, at least in both the Coimbra area (Ferreira soares & al. 1985) and in spain in the vicinity of iron mines. ...
... Na transição dos materiais do Triássico para o Jurássico (topo das Camadas de Pereiros para as bancadas carbonatadas das Camadas de Coimbra) [1], encontram-se os pelitos, que são essencialmente constituídos por silte e argila, de cor predominantemente acinzentada. Os pelitos quando "in situ" comportam-se como uma rocha branda, evoluindo rapidamente para um solo, ou mesmo uma lama, quando descomprimidos e em presença da água. ...
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Os pelitos (siltitos e argilitos) datados do final do Triássico (Hetangiano) tendem a apresentar problemas geotécnicos graves quando sofrem alterações provocadas pelas obras de engenharia, evoluindo rapidamente de uma rocha branda para um solo, quando em presença de água. As situações mais problemáticas referem-se a taludes de escavação, ocorrendo de um modo geral instabilizações durante os primeiros períodos de chuva intensa após a execução da escavações. Para avaliar as características evolutivas destes materiais efectuaram-se ensaios no laboratório. Trata-se de um material singular com poros muito finos, que sofre rápida degradação em presença da água, com perdas de resistência e de durabilidade drásticas, mostrando uma evolução para solo, uma vez destruída a estrutura original da rocha, com velocidade bastante mais rápida do que se levava a inferir pela análise dos casos de obra. ## The mudstones (siltstone and claystone) dated from the end of the Triassic, show severe geotechnical problems when affected by engineering works, changing very rapidly from a soft rock to a soil, when in the presence of water. The more problematic situations are related to excavated slopes, which suffer instabilization after the first intense rainfalls following the execution of the excavation. To evaluate the characteristics of these materials tests were executed in the laboratory. The Triassic mudstones are an unusual material, with very fine pores, suffering rapid degradation in the presence of water, loosing strength and durability, showing an evolution to a soil more rapidly than it was anticipated by the field observations.
... Inúmeros Autores têm realçado, para o espaço de Coimbra, os factores físicos que permitem o entendimento dos processos de perigosidade, e dos factores condicionantes associados, dentre os quais destacamos A. F. Martins (1940); O. Ribeiro (1968); F. Rebelo (1985); F. Soares, Rocha & Marques (1985); A. C. Almeida et al. (1990); F. Rebelo, Cunha & Almeida (1990); A. F. Soares (1990); L. Cunha et al. (1999); A. Tavares (1999Tavares ( , 2003bTavares ( , 2004a, L. Duarte & Soares (2002), A. Tavares & Cunha (2002. ...
... In the chronological limit between Triassic and Mesozoic, in Portugal, there is a very interesting geological material, a pelite, environmentally representing a lagoon where slime and mud sediments were deposited (Soares, A., et al., 1985). The pelite, in situ, behaves as a soft rock, but, in the presence of water, it shows a very sharp transformation into a soil or even a mud. ...
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In Portugal, the Triassic lithology is characterized by a sedimentary sequence representing the erosion that the Iberian craton was subjected. The sediments were transported by rivers and brooks to a basin that was evolving to the so-called Lusitanian Basin. In the chronological limit between Triassic and Mesozoic, there is a very interesting geological material, a pelite, environmentally representing a lagoon where slime and mud sediments were deposited. Due to the diapiric tectonic, there are outcrops of this dark gray pelite between Coimbra and Torres Vedras, in a distance about 120 km long. This pelite is a very interesting material because during the raining season shows a very plastic behaviour, causing slope stability problems in urban areas and in highways. Stratigraphically above this pelite, thicker limestone sequences occur and it’s normal to observe the collapse of the limestone. In summer season, the pelite looses water and turns to be a high stiffness material, difficult to work with. These so different seasonal behaviours and their consequence on environmental geology motivated the research work on the characterization of the pelite. The pelite was characterized in terms of mineralogical, physical and technological properties, especially density and rheology. The other direction aims at establishing a correlation between the rheological characteristics of this geological material with mineralogy and engineering geology was also analysed.
... ML2302 was recovered in the lower part of the Coimbra Formation (Fig. 1D). This formation has been traditionally subdivided into two informal units, dolomite and limestone members (Azerêdo et al. 2003) or "Camadas de Coimbra" and "Calcários de S. Miguel" (Soares et al. 1985). In more recent and detailed sedimentological studies, the Coimbra Formation, in the section located between Praia Velha and Praia da Concha (Fig. 1C-F) (Praia da Concha-Farol section of Duarte et al. 2014b), has been divided into seven informal units (UA-UG) (Azerêdo et al. 2010;Duarte et al. 2014b). ...
... A área em estudo -o concelho de Coimbra -constitui um bom exem- plo para compreender a manifestação temporal e espacial de processos naturais potencialmente perigosos, particularmente os que se relacionam com as influências do clima: tempestades, ondas de calor e de frio, inun- dações, movimentos de materiais em vertentes e incêndios florestais (REBELO, 1985;SOARES et al., 1985;CUNHA et al., 1999;CUNHA & DIMUCCIO, 2002;TAVARES & CUNHA, 2004, 2008SOARES et al., 2005;DIMUCCIO et al., 2006;PAIVA, 2011). ...
... The soil from Relvinha has a chemical composition more similar to the soils from the phyllite areas, than the soil from Souselas (Table 1). This can be explained by two factors: 1) the parent material in Relvinha has an higher marl content than in Souselas; 2) in Relvinha the soil has a transported component, derived from a terrace deposit of red sands (Areias Vermelhas do Ingote, Soares & al. 1985), located at higher altitude, above up-stream Relvinha, as quartz pebbles were identified during field work in this soil. ...
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The influence of soil on plant cover was investigated in two different soil types, on limestone and on phyllite, in the Coimbra peri-urban area. Two areas were selected in each soil type. Soil was analysed for colour, pH, electrical conductivity, moisture, organic matter content, mineralogy , texture and chemical composition. Floristic composition was assessed and abundance was calculated using DAFOR methodology. Data were statistically analysed in Canoco for Windows 4.5. The two soil types have distinct texture and distinct mineralogical, physical and chemical properties. Soil on limestone had pH, electrical conductivity and moisture content higher than soil on phyllite; the latter had higher organic matter content. Soil on limestone had silt clay loam texture and the most abundant minerals were calcite and quartz. The texture of soil from phyllite is sandy loam, loam and silt loam and the most abundant minerals were quartz and mica. Also, most common oxides and trace elements are different. A total of 288 taxa in 61 families (Fabaceae, Asteraceae, and Poaceae are predominant) were identified, showing the enormous diversity of the peri-urban vegetation of Coimbra. A clear distinction was found between the vegetation of the areas of limestone and phyllite; the main environmental factors influencing the ordering of species are pH, mineralogy and anthropic impact.
... Impacts caused by leaf-cutter ants, or bioperturbation, are associated with their behavior of cultivating symbiotic fungus in subterranean chambers linked through a network of tunnels131415. In order to build these chambers, worker ants remove soil to depths up to 7 m [16] and deposit it on the soil surface, forming a mound, a characteristic heap of soil [15, 17, 18]. During ant nest excavation and expansion, the leaf litter and nearby seedlings are buried or removed, which effectively leaves the mound completely bare. ...
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Leaf-cutter ants (Atta spp.) remove leaf litter and woody debris—potential fuels—in and around their nests and foraging trails. We conducted single and three annual experimental fires to determine the effects of this leaf-cutter ant activity on the behavior of low-intensity, slow-moving fires. In a transitional forest, where the southern Amazon forest meets the Brazilian savanna, we tested whether leaf-cutter ant nests and trails (i) inhibit fire spread due to a lack of fuels, and (ii), thereby, reduce the total burned area during these experimental low-intensity fires, particularly at forest edges where leaf-cutter ant abundance was higher. Fine-medium fuel mass increased with an increase in distance from ant nest, and the mean area of bare soil was greater on nests than on the forest floor. Between 60 to 90 percent of the unburned area was within 30 m of ant nests, and burned area significantly increased with increasing distance to ant nests. In addition, the number of ant nests declined with increasing distance from the forest edge, and, with exception of the first experimental fire, burned area also increased with increasing distance from the edge. The present study provides new insight to fire ecology in Amazon environments.
... No seu percurso, através do interior do Distrito de Coimbra, atravessa sucessivamente os concelhos de Arganil, Góis, Lousã, Miranda do Corvo e Pampilhosa de Serra, confluindo com o rio Mondego quando este inicia o seu percurso através da cobertura sedimentar da Orla Meso-Cenozóica Ocidental. Neste sentido, apraz observar que a união destes dois cursos irmãos, ora mansos, ora rebeldes no pico da invernia, tem por cartão-de-visita os derrames conglomeráticos da mais antiga unidade detrítica do Mesozoico portuguêsa Formação de Conraria (SOARES et al., 1985(SOARES et al., , 2012SOARES e GOMES, 1987). (DAVEAU, 1976;SOARES et al., 1983;DAVEAU et al., 1985/86;CUNHA, 2002 (REBELO, 1985), produzem muitos exemplos notáveis de interesse geomorfológico, tonificando as paisagens com o cunho da sua imponência. ...
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Este estudo teve como objetivo principal apresentar exemplos que, sobretudo, pelo seu interesse geomorfológico, constituem locais ímpares, no vale do rio Ceira, entre Coimbra e a Lousã. Os exemplos selecionados: 1) a Paisagem da Senhora da Candosa, marcada sobretudo pela atuação do rio Ceira, em que os quartzitos do Ordovícico do Maciço Hespérico, fortemente inclinados, se apresentam rasgados em vale profundo; 2) a seção do rio Ceira, em depressão, que se avista da Senhora da Candosa, 3) o Cabril do Ceira, onde o vale se apresenta encaixado nos quartzitos do Ordovício; 4) a discordância angular entre as unidades do Paleozoico e as do Cretácico da Bacia da Lousã; e 5) o sinclinal que deforma as unidades do Paleozoico, apresentam uma localização e acessibilidade adequadas e têm sido usados na construção de recursos, no âmbito do ensino das Geociências. ________________________________________ ABSTRACT The main objective of this study was to present examples of geomorphosites in the Ceira River valley between Coimbra and Lousã, Central Portugal. Selected examples are 1) the landscape of Senhora da Candosa, especially noteworthy for the action of Ceira River, such that the Ordovician quartzites of the Hesperian Massif, on a steep incline, are torn into a deep valley; 2) the section of the Ceira River in a depression, which can be seen form Senhora da Candosa; 3) the Cabril do Ceira, where the valley in encased in Ordovician quartzites; 4) the angular unconformity between the Paleozoic and Cretaceous units in the Lousã Basin; and 5) the syncline that shapes the Paleozoic units. They present a convenient location and have been used in the building of resources for the teaching of Geosciences.
... Como consequência deste percurso complexo, o seu espaço citadino está eivado de um misto de elementos históricos e naturais, dispersos no seio de um edificado multifacetado que se desenvolveu como fruto da necessidade dos homens e do seu percurso civilizacional, numa contínua e profunda ação de antropização da paisagem. (SOARES et al., 1985(SOARES et al., , 2005(SOARES et al., , 2007; SOARES e GOMES, 1997). Juntam-se, assim, episódios muito antigos da evolução geológica do território, com outros ligados essencialmente ao ciclo atlântico e à génese da Bacia Lusitânica, no contexto da margem continental oeste da Paleomicroplaca Ibérica. ...
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A importância científica e pedagógica de algumas das paisagens urbanas da cidade de Coimbra, região centro de Portugal, deve-se à singularidade das formas do relevo locais. Os objetivos gerais deste estudo foram: 1) selecionar os critérios de identificação e avaliação de "locais de interesse geomorfológico" (LIGs, no sentido de geomorphosites); 2) revelar os LIGs selecionados; e 3) apresentar os LIGs, no âmbito das Cidades Educadoras. Estes locais foram selecionados considerando os resultados de trabalhos de campo e da bibliografia e cartografia publicadas. A seleção final inclui os sítios: 1) Penedo da Saudade; 2) Penedo da Meditação; 3) Miradouro do Vale do Inferno; 4) Colina do Polo I da Universidade de Coimbra; e 5) Vale do Rio Mondego. Nela foram considerados, como principais critérios interrelacionados, a localização, a acessibilidade, a importância histórica, turística e cultural e, sobretudo, a adequação a estratégias e atividades educacionais. Palavras-chave: Cidade educadora, Coimbra (Portugal), Educação em Geomorfologia, Locais de interesse geomorfológico. ______________________________ ABSTRACT The scientific and pedagogical importance of some of the urban landscapes of the city of Coimbra, in the central region of Portugal, is due to the uniqueness of the local forms of relief. The aims of this study were: 1) to select the criteria for the identification and evaluation of "sites of geomorphological interest (SGIs)" (geomorphosites); 2) to reveal the SGIs selected; 3) to present the SGIs in the context of Educating Cities. These sites were selected based on the results of field work and published literature and cartography. The final selection includes the sites: 1) Penedo da Saudade; 2) Penedo da Meditação; 3) Vale do Inferno Viewpoint; 4) Hill of Polo I (Hub I) of the University of Coimbra, and 5) The Valley of the Rio Mondego. Location, accessibility, historical importance, cultural and tourism and especially the adequacy for educational strategies and activities were considered as major interrelated criteria in the selection.
... Esta mesma arquitectura foi posteriormente ajustada (A. F. Soares et al., 1985) ao sentir litostratigráfico que o uso já impunha (Fig.1). Soares, et al., 2008, Quadro I, p. 17 O confronto das informações decorrentes dos estudos publicados por P. Choffat (1894Choffat ( , 1903Choffat ( , 1905, Soares de Carvalho (1946), H. da Silva (1951) e Ch. ...
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RESUMO O Grupo de Silves (Carniano?-Hetangiano), base do Mesozóico em Portugal, organiza-se, para Norte do Tejo, por megassequências no sentido de Ch. Palain. Trabalhos recentes de cartografia mostraram-nos que: (1) a base da megassequência MS1 (Formação de Conraria) tem espessura muito variável (<50m), chegando mesmo a desaparecer; (2) o Grés com Voltzia tem espessura máxima em Coimbra (90±15m) decrescendo para sul (Carniano inferior?); (3) em descontinuidade sucede a megassequência MS2 (Formação de Penela) com 116±20m e que termina, localmente, por um corpo (10-16m) de areno-pelitos castanhos com raros dolomitos (Camadas de Melhorado); (4) sobre este corpo, dominantemente vermelho e em discordância, sucede a megassequência MS3 (= Grés à nuances claires = Formação de Castelo Viegas), possivelmente Retiano-Hetangiano (60-113m) e que termina por um corpo areno-dolomítico com fósseis de ambientes marinhos (Camadas com Isocyprina e Promathildia) e que tem sido tomada como base cartográfica do Jurássico. A megassequência MS4 (=Formação de Pereiros) é essencialmente pelito-dolomítica, com espessura variável (50-110m), crescendo para Sul (Avelar) e para Norte (Sangalhos). Em descontinuidade estão os dolomitos da base da Formação de Coimbra de idade sinemuriana. Para Ocidente, no seio dos vales tifónicos, aflora a Formação de Dagorda, possível equivalente lateral de grande parte das unidades do Grupo de Silves. //// ABSTRACT Silves Group is the base of the Mesozoic (Carnian?-Hettangian) in Portugal. It organizes, North from Tejo, in megasequences in the sense of Ch. Palain. Recent cartography works show that: (1) The base of the megasequence MS1 (Conraria Formation) has a very variable width (< 50m), totally disappearing in certain places. (2) The unit Sandstones with Voltzia has a maximum width near Coimbra (90±15m) decreasing to the south (Lower Carnian?). (3) The megasequence MS2 (Penela Formation) lies with an unconformity over the previous unit and has a thickness of 116±20m. It finishes locally by a succession of (10-16m) brown sandy pelites interbedded with rare dolomites (Melhorado Beds). (4) This unit is overlain by discordant, mainly reddish beds of the megasequence MS2 (= Grès à nuances claires = Castelo Viegas Formation), possibly from Rhaetian-Hettangian age (60-113m). This megasequence ends with a sandydolomite succession with fossils from marine environments (Isocyprina and Promathildia Beds). This unit has been used as a cartographic base of the Jurassic. The megasequence MS4 (Pereiros Formation) is essentially pelite-dolomitic with a variable thickness (50-110m) that increases towards south (Avelar) and north (Sangalhos). The Sinemurian dolomites from the base of Coimbra Formation are discontinuous over these units. To the west, in the core of the typhonic valleys, the Dagorda Formation arises, as a possible lateral equivalent of the most part of the Silves Group units.
... Nesta nova fase, das tais que o pintor e o paleontólogo atravessam ao longo das suas existências, os fósseis, quando presentes, passaram a estar subordinados à Estratigrafia e ao interesse pela (re)defenição das unidades estratigráficas pós-jurássicas da região do Baixo Mondego (Soares et al., 1982(Soares et al., , 1985Soares & Pena dos Reis, 1984). É também, nestes anos de charneira, que a atenção do eternamente paleontólogo António Soares, diverge progressivamente para outros espaços e tempos, numa ânsia crescente de aprendizagens. ...
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Resumo: O Professor António Ferreira Soares dedicou mais de 50 anos da sua carreira universitária ao estudo da Paleontologia e Estratigrafia. Deixou uma obra paleontológica de vulto, repartida por vários períodos e temas: (1) Paleontologia sistemática do Cretácico e Miocénico de Angola e Moçambique (1958-1970); (2) Sistemática, biostratigrafia e paleoecologia do Cretácico superior português, com destaque para a região do Baixo Mondego (a partir de 1960, com maior ênfase nas décadas de 60 e 70); (3) Paleontologia do Miocénico e Quaternário das Ilhas Atlânticas, com destaque para Porto Santo (1972 em diante); (4) Biostratigrafia do Triásico, Liásico e Dogger da Orla Meso-Cenozóica Ocidental (a partir da década de 80); e (5) Faunas subfósseis dos depósitos plistocénicos e holocénicos (anos 90 em diante). A presente síntese dá conta deste vasto historial e percurso singulares, a figurarem por mérito próprio na história e epistemologia da Paleontologia em Portugal. Abstract: The Professor António Ferreira Soares has spent more than 50 years of his universitary career studying Palaeontology and Stratigraphy. He left an important reference work on the domains of Palaeontology, which can be divided on several periods and themes: (1) Systematic Palaeontology from the Cretaceous and Miocene of Angola and Mozambique (1958-1970); (2) Systematics, biostratigraphy and palaeoecology from the Upper Cretaceous of Portugal, with emphasis on the Baixo Mondego region (West Central Portugal) (after 1960, but with more incidence during the 60’s and 70’s); (3) Miocene and Quaternary Palaeontology from the Atlantic Is., including Porto Santo (after 1972); (4) Triassic, Liassic and Dogger biostratigraphy of the Western Portuguese Border of Iberia (Lusitanian Basin) (during and after the 80’s); and (5) Sub-fossil faunas from Pleistocene and Holocene deposits (from 90’s upwards). Next synthesis intends to be a state of the art regarding his large career and historic of researches, which will remain by merit on the history and epistemology of Palaeontology on Portugal.
... In the Upper Cretaceous post-rift series, mostly absent from Algarve and recorded in the onshore sectors of the Portuguese ranges of the West Iberian Continental Margin, there was also a considerable work developed in the Baixo Mondego region, by Soares et al. (e.g. Soares 1960, 1966, b, 1972, 1980Soares and Devriès 1967;Soares and Marques 1973;Lapa 1979;Soares et al. 1982Soares et al. , 1983Soares et al. , 1985Soares et al. , 1986Barbosa et al. 1988), together with Romariz (1960, Groot and Groot (1961), Antunes and Pais (1978), Barbosa (1981), Reis (1981) and Rocha et al. (1981), among several other relevant contributions. At the same time, Ferreira (1961), Berthou et al. (e.g. ...
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Major changes occurred in Iberia during the Late Cretaceous. First, the cessation of the previous rifting episode derived into generalized thermal subsidence in all basins, which in conjunction with warm climate and high sea-levels promoted the widest carbonate platforms ever in Iberia. Second, that post-rift interval was punctuated regionally by a series of tectonic episodes related to intraplate stresses which induced complex paleogeo-graphic patterns, and locally by intense salt tectonics. And third, the onset of Africa-Iberia-Europe convergence, which started in Santonian times, determined the first Alpine contractional episodes in Iberia, which caused major changes in all sedimentary basins. The chapter reviews all those points in an integrated approach through the basins of Iberia. In the broad frame of the break-up of Pangea, which led to the gradual opening of the western Tethys and the Atlantic, the Late Jurassic to Early Cretaceous interval was characterized by extensional and transtensional processes in Iberia that had determined a prolonged and complex rifting interval, affecting all the sedimentary basins (see Chaps. 5 and 6). That rifting period was followed, from the late Albian onwards, by a long time interval which was dominated by relative tectonic quiescence and regional thermal subsidence in the former sedimentary basins. The new conditions caused a significant “homogenization” of the tectono-sedimentary conditions relative to the former extensional behavior. Despite the dominant post-rift tectonic conditions, the evolution of the sedimentary basins was far from straightforward, as Iberia and its basins were strongly sensitive to the movements occurring in the surrounding major plates (Africa and Europe). In fact, a series of tectonic changes occurring at the plate boundaries punctuated and controlled the broad evolution of the various basins. The main change occurring during the Late Cretaceous interval was probably the one related with the onset of Europe—Iberia—Africa convergence, in the late Santonian. This geodynamic change had strong effects in the Pyrenees, causing the structuration of the first thrust sheets in that area and the development of the foreland basins, but also affected the rest of the plate with strong changes in all the post-rift sedimentary basins, which started their way towards inversion and contractive deformation. This chapter is structured in five main sections: (1) a general introduction to Iberia and its sedimentary basins in the Late Cretaceous world, with emphasis in paleogeography, climate, and geodynamics; (2) an integrative synthesis of the Late Cretaceous evolution in a north to south transect of Iberia, covering from the North Iberian Continental Margin to the South Iberian Continental Margins, and including the intracontinental Iberian Basin in between, the later determining the formation of a wide marine embayment or gulf from each of the two continental margins toward the Iberia interior; (3) a review of the evolution of the South Pyrenean basins from the end of extensional tectonics in the Late Albian to the first stages of contraction (late Santonian to Maastrichtian), and including the generation of highly subsiding basins related to salt tectonics in the post-rift pre-contractive interval; (4) a modern synthesis of the paleogeographic evolution of the West Iberian Margin based in the Portuguese onshore outcrops; and (5) a final section of integration of the evolution of the different basins and domains in the framework of the geodynamic evolution of Iberia.
... In the Upper Cretaceous post-rift series, mostly absent from Algarve and recorded in the onshore sectors of the Portuguese ranges of the West Iberian Continental Margin, there was also a considerable work developed in the Baixo Mondego region, by Soares et al. (e.g. Soares 1960, 1966, b, 1972, 1980Soares and Devriès 1967;Soares and Marques 1973;Lapa 1979;Soares et al. 1982Soares et al. , 1983Soares et al. , 1985Soares et al. , 1986Barbosa et al. 1988), together with Romariz (1960, Groot and Groot (1961), Antunes and Pais (1978), Barbosa (1981), Reis (1981) and Rocha et al. (1981), among several other relevant contributions. At the same time, Ferreira (1961), Berthou et al. (e.g. ...
Chapter
Major changes occurred in Iberia during the Late Cretaceous. First, the cessation of the previous rifting episode derived into generalized thermal subsidence in all basins, which in conjunction with warm climate and high sea-levels promoted the widest carbonate platforms ever in Iberia. Second, that post-rift interval was punctuated regionally by a series of tectonic episodes related to intraplate stresses which induced complex paleogeographic patterns, and locally by intense salt tectonics. And third, the onset of Africa-Iberia-Europe convergence, which started in Santonian times, determined the first Alpine contractional episodes in Iberia, which caused major changes in all sedimentary basins. The chapter reviews all those points in an integrated approach through the basins of Iberia.
... Castilian platforms, (Fig. 4.2 f, h; Fernández- López et al. 15461978, 1985Fernández-López 1985;Gómez 1985a, b, 19911547 Friebe 1995). 1998; Gómez andFernández-López 2004b, 2006 ...
Chapter
During the Late Triassic-Middle Jurassic interval Iberia acted as a passive margin, where extensional or transtensional faulting, linked to the propagation of the Central Atlantic and the opening of the Ligurian Tethys, generated a NW and NE trending fault system that conditioned facies and thickness distribution. These faults also favored the implantation of mantle plumes and associated volcanism, giving rise to the evolution from a magma-poor passive margin, during the latest Triassic to the Pliensbachian, to a magma-rich passive margin, which developed from the Pliensbachian to the Bajocian. Progressive extensional faulting, that propagated from east to west reached a climax during the Toarcian, probably related to the onset of sea-floor spreading in the northern part of the Central Atlantic.
... Sur le plan géologique, on peut clairement distinguer les terrains à prédominance schisteuse du Massif hespérien (Fig. 1), représentés sur les versants du Massif marginal de Coimbra (alt.max. : 535 m) à l'est, des terrains sablo-conglomératiques (consolidés et non consolidés), calco-dolomitiques et calco-marneux de la Orla meso-cenozoica ocidental de Portugal (SOARES et al., 1985(SOARES et al., , 2005(SOARES et al., , 2007SOARES & MARQUES, 2004 ;REBELO, 1985 ;CUNHA et al., 1999;TAVARES, 1999;TAVARES & CUNHA, 2004) représentés topographiquement par de douces collines de basse altitude (c. 200-300 m), à l'ouest ( Fig. 2). ...
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The general objective of this preliminary study is to define an integrated spatial modelling of natural risks for the Coimbra municipality (western-central Portugal), making it possible to establish intervention priorities for its mitigation. Indeed, this selected study area is an example of the persistence occurrence of potentially dangerous natural events, in time and space, particularly those linked to the environmental influences typical of the Mediterranean climate (extreme weather phenomena, heat and cold waves, floods, landslides and forest fires). Conventionally, risk assessment focuses on individual hazards and vulnerabilities, but the importance of addressing hazards collectively has been recognized here. Indeed, the aims is to develop a more complete understanding of natural multi-hazards by assessing and mapping either the relative danger or the suffered damage, on social, economic and environmental plan. The occurrence of dangerous natural events on a selected territory is crucial for defining the susceptibility or the probability of occurrence of unwanted and dangerous events, as well as for studying the possibility that a natural event may trigger another - cascade or domino effect. This research integrates different methodological approaches (definition of a multi-hazard index, artificial neural networks, geographic information systems and probabilistic analysis) on the same territory. Monothematic susceptibility (hazard?) maps, at the municipality level, will be produced. Through this analysis is expected to create a framework containing the main hazardous processes and most of the complex relationships and interconnections between them. In addition, this framework will also enable the precise mapping of the different degrees of multi-hazard zones, which is very important to achieve an integrated risk management model for the Coimbra municipality. From this perspective, it will be possible to plan the actions needed to reduce (or mitigate) hazard, exposure and vulnerability, and to promote the development of a resilient territorial system.
... The marls are brown-yellow to bluish and the limestones are yellow, and both show joins and normal NNE-SSW faults. Discordantly covering the marls and marly limestone occur clastic units (conglomerates and sandstones) of Pleistocene age (Soares et al., 1985). ...
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A great number of potentially toxic elements are introduced into soils by numerous anthropogenic activities, such as the foundry industry and may have negative consequences on the environment and subsequently on human health. This paper reports the characterization of soil samples collected at the facilities of an old foundry, already demolished, that operated during the last century in an industrial area in the Center of Portugal, Coimbra. The mineralogy, physicochemical parameters, and geochemistry of the soil foundry's area, were studied and compared with regional soil parameters to understand the impact of the foundry's activity on the soil. The enrichment and degree of contamination in the factory soil were also assessed, according to public guidelines. Foundry soil was found to exhibit higher average contents of Al2O3, Fe2O3(t), SiO2, TiO2, Zr, Sr, Rb, Pb, Zn, Cu, V, Nb, and Bi, than the corresponding regional baseline values. Specifically, the soil in the foundry area is polluted with Cu, Pb, and Zn. PCA analysis allowed to distinguish the natural soil from the foundry contaminated soil and the contribution of the spent sands and iron slags in the modification of the geochemistry of the regional soil. The contaminants and pollutants are not uniformly distributed as they show the higher concentrations in places of local storage, disposal, and finishing of materials used in the foundry.
... Inúmeros Autores têm realçado, para o espaço de Coimbra, os factores físicos que permitem o entendimento dos processos de perigosidade, e dos factores condicionantes associados, dentre os quais destacamos A. F. Martins (1940); O. Ribeiro (1968); F. Rebelo (1985); F. Soares, Rocha & Marques (1985); A. C. Almeida et al. (1990); F. Rebelo, Cunha & Almeida (1990); A. F. Soares (1990); L. Cunha et al. (1999); A. Tavares (1999Tavares ( , 2003bTavares ( , 2004a, L. Duarte & Soares (2002), A. Tavares & Cunha (2002. ...
... Sur le plan géologique, on peut clairement distinguer les terrains à prédominance schisteuse du Massif hespérien (Fig. 1), représentés sur les versants du Massif marginal de Coimbra (alt.max. : 535 m) à l'est, des terrains sablo-conglomératiques (consolidés et non consolidés), calco-dolomitiques et calco-marneux de la Orla meso-cenozoica ocidental de Portugal (SOARES et al., 1985(SOARES et al., , 2005(SOARES et al., , 2007SOARES & MARQUES, 2004 ;REBELO, 1985 ;CUNHA et al., 1999;TAVARES, 1999;TAVARES & CUNHA, 2004) représentés topographiquement par de douces collines de basse altitude (c. 200-300 m), à l'ouest ( Fig. 2). ...
Article
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Abstract : The general objective of this preliminary study is to define an integrated spatial modelling of natural risks for the Coimbra municipality (western-central Portugal), making it possible to establish intervention priorities for its mitigation. Indeed, this selected study area is an example of the persistence occurrence of potentially dangerous natural events, in time and space, particularly those linked to the environmental influences typical of the Mediterranean climate (extreme weather phenomena, heat and cold waves, floods, landslides and forest fires). Conventionally, risk assessment focuses on individual hazards and vulnerabilities, but the importance of addressing hazards collectively has been recognized here. Indeed, the aims is to develop a more complete understanding of natural multi-hazards by assessing and mapping either the relative danger or the suffered damage, on social, economic and environmental plan. The occurrence of dangerous natural events on a selected territory is crucial for defining the susceptibility or the probability of occurrence of unwanted and dangerous events, as well as for studying the possibility that a natural event may trigger another - cascade or domino effect. This research integrates different methodological approaches (definition of a multi-hazard index, artificial neural networks, geographic information systems and probabilistic analysis) on the same territory. Monothematic susceptibility (hazard?) maps, at the municipality level, will be produced. Through this analysis is expected to create a framework containing the main hazardous processes and most of the complex relationships and interconnections between them. In addition, this framework will also enable the precise mapping of the different degrees of multi-hazard zones, which is very important to achieve an integrated risk management model for the Coimbra municipality. From this perspective, it will be possible to plan the actions needed to reduce (or mitigate) hazard, exposure and vulnerability, and to promote the development of a resilient territorial system.
... Em termos geológicos gerais, corresponde a uma sucessão de unidades sedimentares com uma estrutura monoclinal para Oeste, aqui e além afetadas por importantes falhas. Destas unidades destacam-se, pela sua importância nos processos de carsificação (solubilidade e permeabilidade em grande), as rochas do chamado Grupo de Coimbra (Formação de Coimbra + Formação de S. Miguel;SOARES et al., 1985SOARES et al., , 2007 (SOARES et al., 2007). ...
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Resumo: Associando-nos à justa homenagem que se presta ao Professor Doutor António Ferreira Soares, pretende-se reflectir sobre o seu contributo para o conhecimento geomorfológico do espaço do Baixo Mondego. Para tal, passam-se em revista os trabalhos que desenvolveu sozinho ou em equipas por si lideradas nas áreas de Coimbra, Condeixa, no vale do Baixo Mondego e na Serra da Boa Viagem, tentando mostrar o contributo do trabalho que desenvolveu nos últimos 20 anos para o avanço registado no conhecimento geomorfológico desta área do país e do Quaternário português. Abstract: Joining with the fair homage paid to Professor António Ferreira Soares, we intend thinking over his contribution for the geomorphologic knowledge of Low Mondego. For that, papers developed by himself or by teams with his leadership and referred to Coimbra, Condeixa, Low Mondego valley and Serra da Boa Viagem, were reviewed. An effort is attempted to display the importance of the work he developed, especially during recent 20 years, for the progress of the geomorphologic knowledge of both this area and the Portuguese Quaternary.
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No Centro Litoral de Portugal continental, no espaço que estruturalmente pertence à chamada Bacia Lusitânica, as rochas carbonatadas jurássicas são responsáveis por um conjunto de pequenos Maciços Calcários, salientes na paisagem, quer pelo comportamento diferencial das litologias, quer pela atuação da tectónica alpina. Nestes maciços, os processos de evolução cársica, relacionados com a solubilidade da rocha e com a sua permeabilidade “em grande” são responsáveis por paisagens com características bem particulares, em que a tendência para a formação de bacias fechadas à superfície se adequa à proliferação de cavidades subterrâneas. Destes, o Maciço de Sicó, apesar da sua reduzida dimensão (pouco mais de 400 km2) apresenta nos seus diferentes compartimentos uma enorme variedade de formas cársicas (lapiás, dolinas, canhões fluviocársicos, grutas, abrigos sob rocha, exsurgências), muitas das quais com elevado valor em termos patrimoniais, mas também com alguns problemas de geoconservação. A especificidade morfológica do Maciço de Sicó advém sobretudo de se tratar de um carso coberto, com uma exumação incompleta em que os processos cársicos e fluviais interagiram e interagem na construção de uma paisagem em que os vales fluviocársicos, as formas superficiais fechadas, as grutas, as “buracas” e os lapiás coexistem num sistema complexo resultante de uma evolução polifásica e poligénica em que se encontram refletidos diferentes tempos e distintos ambientes.
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A formal lithostratigraphic framework is proposed for the Lower Jurassic dolomitic-limestone succession of Lusitanian Basin, cropping out in the Coimbra-Penela region (western-central Portugal). In this proximal domain of the basin, the Coimbra Formation (Early to Late Sinemurian) and the S. Miguel Formation (Late Sinemurian to Early Pliensbachian) were defined and characterized in according with the normative imposed by the International Stratigraphic Guide. In turn, the Coimbra Formation is subdivided into two members: the Vila Seca Member, at the base, and the Casa do Sal Member, at the top. The proposed units locally reach a combined total thickness of ca. 110 m. The available biostratigraphic references of ammonites and of benthic fauna, by comparison with the profiles from the distal domain (S. Pedro de Moel and Peniche), allow the interpretation of an original regional correlative framework. Keywords: Coimbra Formation, S. Miguel Formation, lithostratigraphy, Sinemurian-Early Pliensbachian, Lusitanian Basin.
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