391 resultados para NW de Portugal


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The presence of the genus Rupicapra in Portugal is shown for the first time, on some dental and skeletal remains from the upper Pleistocene (Solutrean) of Salemas cave. The fossil material may be ascribed to R. rupicapra pyrenaica.

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Twelve new species of miocene ostracoda from the Tagus basin (Portugal) are described. Paleoenvironments concerning each of these species are given.

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New radiocarbon measurements were obtained from middle and upper Paleolithic sites currendy under research by the CEPUNL, in well defined stratigraphical situations. With other dates, they yield an approximative chronological global view. Measurement dístribution in function of time does not seem to be an hazardous one. ln the actual status of our knowledge, this distribution seems to fit in some assemblages: (a) 14000 to 15000 BP, Solurrean ; (b) about 20 000 BP, Solurrean ; (e) area 25 000 BP, already Solurrean, and slightly older than 26 000 BP, still Mousterian ; (d) between 29 000 and 31 000 BP, Mousterian. The persistance of Mousterian much later than its acknowledged upper limit at about 34 000 BP (and hence the survival of its neanderthalian authors) is demonstrated. For the first time it has been possible to ascertain the upper time limit of the marine 5-8 metres raised beach (Tyrrhenian III) at Serra da Arrábida, and also the age of archaeological sires wirhout srone arrifacts, or with uncharacteristic ones. The obtained measurements allow us to correlate localities and sedimentary units with last glaciation events. There seems to have been a distinct correlation between cave and shelter human occupation and events marked by the worsening of climate.

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EEZ International, Summer 2003, p. 43-47

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In this paper, a synopsis on the already known data, and the study of further specimens either new (*) or hither to undescribed are presented. The specimens dealt with have been collected at the Condeixa travertines; in the Tagus terraces near Carregado(*) and at Foz do Enxarrique(*); in the mousterian, about 31000 BP infilling from the Figueira Brava cave(*); and at Algar de Joao Ramos(*). Some specimens are ascribed to Elephas antiquus, the best represented form. Material from Figueira Brava cave and Algar de João Ramos is ascribed to Mammuthus primigenius, a species recognized here for the first time in Portugal.

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A fragment of the lower jaw of cuon (Cuon alpinus europaeus BOURGUIGNAT, 1868) found at gruta do Escoural is studied. It is the first occurrence recorded for the Pleistocene of Portugal.

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The presence of Palaeotherium magnum in the fauna from Coja is recorded. It is well in agreement with the earlier reporting to the Montmartre level from the Ludian stage. Field data as well as compatibility with the remaining taxa and the identical fossilization of all the specimens indicate that all the vertebrate fossils come from the same horizon in the lithostratigraphic unit "Arcoses de Côja".

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The result of research conducted in trunk fragments from the Coja Arkoses Formation at Naia and Sobreda is reported. It is also reported the palynological study of the lutaceous black level surrounding the Naia trunk. Comparisons with trunks from Nave de Haver are established. Comments on palaeoecology and palaeoclimatology are presented.

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This paper represents the first detailed study of the Transversarium-Bifurcatus Zone boundary in the Algarve. The boundary studied in the Peral area is associated with a stratigraphic discontinuity, whose hiatus partially affects the Transversarium-Bifurcatus Zones. A discontinuity was also recognized in the Bifurcatus-Birnammatum Zone boundary, which can be correlated with the traces of a Type II unconformity, which separates cycles 4.3-4.4 in HAQ et al. (1987), present on the South Iberian palaeomargin. An analysis was made of the ecostratigraphic evolution in the interval between the uppermost Transversarium Zone and the lower part of the Bimammatum Zone on the basis of the faunal spectra obtained. We conclude that ammonites are the most tolerant cephalopods to the ecological stress caused by the increase of inflows and the decrease of the shelf's ecospace. Benthic fauna decreased considerably in these conditions. A relatively abundant and diversified fauna ofDichotomoceras is noteworthy among the ammonites collected, as this genus was previously little known in the Algarve.

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Vilar de Frades church is integrated in the Vilar de Frades Monastery, located in the North part of Portugal (Barcelos). The monastery, founded in 566, suffered several architectural modifications and restoration works, the most relevant was in the XVI century. The church, in granite, has one nave and six bays,holding ten chapels with vaults of crossed ribbings. Nowadays, the chapels present a severe biological colonization characterised by an intense green biofilm, which becoming apparent in other locations inside the church. In the course of a general survey concerning the conservation state of the church, an accurate campaign was planned in order to assess the main biodeterioration agents, map biological colonization and determine the environmental conditions. Laboratory analyses were accomplished with optical microscopy and spectrofluorometry. This study presents the results of this campaign. Details on conservation or preservation works that need to be implemented are also presented.

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The magnetostratigraphy of two sections in early Miocene marine deposits of the Tagus Basin is studied. Thermal demagnetization was used to isolate the primary component of magnetization for 45 samples from the Foz da Fonte section, and for 74 others from Trafaria section. The succession of the polarity zones found in these sections is tentatively correlated with the geomagnetic polarity time scale (GPTS) on the basis of the biostratigraphic data yielded by planktic Foraminifera. The planktic zones and magnetic polarities recognized in these sections can be adequately correlated with the part of the GPTS [table calibrated by BERGGRENET al. (1985)] corresponding to the Anomalies 6 and 5E (Foz da Fonte) and 5D (Trafaria). This correlations suggests ages between 19,35 and 18,14 Ma for Foz da Fonte section, and 17,90 to 16,98 Ma for Trafaria.

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A new upper Miocene locality at Asseiceira (Rio Maior), near the top of the "Calcários de Almoster e Santarém" unit (Almoster and Santarém limestones) is studied. Animal and plant fossils are described. Comparisons are drawn to other localities related to the same unit: Freiria and Azambujeira (middle and upper levels, both with large mammals). Small mammals from Asseiceira and Freiria point out to a rather old age amidst the upper Vallesian, MN 10 mammal-unit. This gives a fairly accurate datation for the "Calcários de Almoster e Santarém" and for the short time span of the corresponding sedimentation. Climate was warm and quite dry, with contrasting seasons and arid events. During upper Vallesian times, climate in Iberian Peninsula was varied but drier than in France, and specially so in the inner basins. However in Portugal and in Catalonia climate would he less different in comparison with that of the Rhône basin. Environmental evolution has been important: at Freiria and Azambujeira (middle level) there were mainly shallow lacustrine environments that received ressurgence waters from the nearby "Maciço calcário". Humid areas were closely surrounded by dense forests and these by broader and drier savanna or steppe areas. Still later, carbonate sedimentation ended. For some time there was still a river system with oxbows; humid areas probably were decreasing in favour of surrounding, rather dry environments. This study stressed the nced for revision of the geology of the region of Rio Maior and for a new geological mapping of that area. Environmental evolution has been important: at Freiria and Azambujeira (middle level) there were mainly shallow lacustrine environments that received ressurgence waters from the nearby "Maciço calcário".

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After a brief historical introduction, this paper deals with the main concerned geotectonic units: the Lower Tagus and Alvalade basins, the Western and Southern borders, and their infillings. Most of the Neogene events and record concern areas South of the Iberian Central Chain, a nearly inverse situation as that of Paleogene times. In the most important of these units, the Lower Tagus basin, there are quite thick detrital series, mostly marine in its distal part near Lisboa (albeit with several continental intercalations), and mainly continental in its inner part. Sedimentological record is almost complete since Lowermost to Upper Miocene. The richness ofdata (paleontology, isotope chronology, paleoclimate, etc.) it gives and the possibility of direct marine-continental correlations render this basin one of the more interesting ones in Western Europe. Alvalade basin is separated from the previous one by a barrier of Paleozoic rocks. Two transgressions events (Upper Tortonian and Messinian in age) are recorded. Active sedimentation may be correlated to Late Miocene tectonics events. In Algarve, chiefly marine units from Lower to Upper Miocene are well developped. The Lower unit (Lagos-Portimão Formation) is best exposed in Western Algarve, but desappears eastwards. Middle Miocene is not as well known, whereas Upper Miocene main outcrops are in Eastern Algarve. Cacela Formation is remarquable for its beautiful fossils. Sedimentation as a whole refletcts the tectonic activity and in special the evolution of the Algarve flexures. There is scant evidence of post-Lower Miocene volcanism, the latest known in Portugal. Pliocene has not been recognized there beyond doubt. Miocene sediments are much less important to the North of the Central Iberian Chain. Continental beds near Leiria that yielded the well-known "Hisp anotherium fauna" are lower Middle Miocene. Pliocene corresponds to dramatic changes in paleogeography. At Setiibal Peninsula there is some evidence of a minor Lower Pliocene transgression. Continental detrital sediments, often coarse, occupy rather large areas. In Western Portugal between the Setúbal Peninsula and Pombal there is good evidence of a marine Upper Pliocene transgression, followed up by dune sands overlain by marsh clays, diatomites, lignites and boghead levels that can be partly Pleistocene in age.

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Proceedings of the I" R.C.A.N.S. Congress, Lisboa, October 1992