Micropalaeontological record of Holocene estuarine and marine

The Corgo do Porto is a small tributary of the Mira River, outleting 3.5 km upstream of its mouth. The valley is flat-floored due to terrigenous siltation and forms an alluvial plain reclaimed for agriculture/aquaculture. These conditions were quite distinct in the recent past because of extensive marine flooding of this area during the high-rate positive eustatism that followed the Last Glacial Maximum. The Holocene sedimen- tary column registers changes imposed by several forcing factors, mainly the climate-driven sea-level rise. As part of a multidisciplinary study, the sedimentological and micropalaeontological (benthic foraminifera and calcareous nannofossils) contents of a core taken from this infill were analyzed, and five different stages were distinguished within its environmental evolution: Stage A (prior to 10,000 cal yrs BP) consists of muddy, matrix-supported sand with abundant pebbles, barren of microfossils, and free of carbonates and organic matter that represents a fluvial envi- ronment contemporaneous of a low sea level. Between 10,000 and circa 4000 cal yrs BP the sediment is made of homogeneous mud, with bio- clasts and organic matter. However, the assemblages of foraminifera and calcareous nannoplankton allowed the identification of several environmental stages, defining a cycle of increasingedecreasing marine influence inside the valley: brackish and brackish-marine sedimentation (Stage B), full-marine sedimentation (Stage C) and a return to brackish-marine sedimentation (Stage D). The final part of the core is barren of microfossils (Stage E) and it represents the modern sedimentation in the area with an accreting alluvial plain. This Holocene sedimentary se- quence reflects an evolutionary succession that closely agrees with the palaeoenvironmental model previously presented by the authors else- where for the south-western Portuguese coast, where a change in the rate of sea-level rise has been recorded at around 5500 cal yrs BP when a very effective sandy barrier formed and isolated restricted brackish to fresh-water lagoonal environments from the open sea

Calibração biostratigráfica das unidades sísmicas da Bacia offshore do Algarve: contribuição do core SWIM04-39

Efectuou-se a calibração estratigráfica das unidades sísmicas mais recentes identificadas na Bacia offshore do Algarve recorrendo à análise biostratigráfica (Nanofósseis calcários e Foraminíferos) do core de pistão SWIM04-39. Obteve-se uma idade de cerca de 4.0 Ma (Pliocénico Inferior, Zancliano) para as associações fitoplanctónica e faunística presente nas amostras do referido core. Estes dados permitiram datar o início da intensa subsidência sofrida por esta Bacia como sendo Pliocénico Inferior

Checklist of the Pleistocene marine molluscs of Praínha and Lagoínhas (Santa Maria Island, Azores).

A critical review of the reported Pleistocene species of and Lagoinhas (Santa Maria Island, Azores) is provided, new data increasing the marine molluscan fauna to 95 taxa (80 Gastropoda and 15 Bivalvia). Six of the reported taxa are considered dubious records (5 Gastropoda, 1 Bivalvia). The stratigraphic sequence of Praia Formosa is composed of two main units, about 2-4 meters above present-day sea level. In the lower unit, Patella ulyssiponensis dominates the fossil assemblage of the basal calcareous conglomerate while Myoforceps arustatus (Dillwyn, 1817) dominates the assemblage associated to a calcareous algae mat. Above a non-depositional hiatus surface, a sandy beach deposit mainly composes the upper unit. Its fossil assemblages are dominated by large amounts of Eruilin castanea (Montagu, 1803) and, in a less extent, Lucinella diwricntn (Linnaeus, 1758) and Ensis minor (Chenu, 1843). The stratigraphic sequence of Lagoinhas, located 7.4 m above present-day sea level, is also composed of two units. A basal conglomerate is fossilized by or passes laterally to a calcareous algae mat, dominated by Myoforceps aristatus and with abundant Calliostoma pecimens. As at Prainha, these lower units are covered by a highly fossiliferous sandy bach deposit, though thinner, in which Ervlie castanea is the dominant species. Some species with Caribbean or West African affinities, the "Strombus bubonius accompanying fauna" (Garcia-Talavera, 1990), were found in the lower layers. The upper layer malacofauna is mainly related to the Mediterranean faunas, similarly to what happens nowadays (Ávila, 2000)

Arouca Geopark: Geotourists are arriving!

1 página.-- IES-04 Geoparks and geotourism.The present work is being performed under the project "Identification, Characterization and Conservation of Geological Heritage: a Geoconservation strategy for Portugal" sponsored by the Portuguese Foundation of Science and Technology (PTDC/CTE-GEX/64966/2006, years 2007-2009), and is also part of the PATRIORSI project of the Spanish Ministry of Education and Science (CGL2006-07628/BTE, years 2006-2009).Peer reviewe

O mar de Olisipo

o estuário do Tejo é um dos maiores estuários da Europa ocidental cobrindo uma área de cerca de 325 km2 de extensão. A incisão do vale onde se desenvolve ocorreu durante os vários períodos glaciares do Quaternário e finalmente durante o Último Máximo Glacial, dando origem a um vale que atinge profundidades superiores a 80 m. Esta depressão morfológica é inundada por águas marinhas durante a rápida subida do nivel médio das águas do mar (N NM) do início do Holocénico, formando uma área de estuário que se estendia até Torres Novas. Após a desaceleração na taxa de subida do NNM, há ca. 7000 anos, dá-se o assoreamento da bacia e a colmatação de alguns afluentes. Iniciam-se nesta altura a formação de praias e áreas de sapal nas margens do estuário. Lisboa localiza-se na margem norte do estuário do Tejo. É uma cidade com uma história longa, que recua à Pré-história. Surge, no entanto, como cidade entre a Idade do Ferro e o Período Romano na área que hoje corresponde à zona baixa da cidade. Durante a Idade do Ferro inicia-se a ocupação das margens do Esteiro da Baixa, um vale que resulta da confluência de duas ribeiras (ribeiras de Valverde e de Arroios), mas é durante o Período Romano que ocorrem as primeiras manipulações antrópicas no Esteiro da Baixa e da frente ribeirinha de Lisboa, e que provocam uma alteração na dinâmica ambiental desta margem estuarina assim como mudanças à linha de costa estuarina. Após o Período Romano a frente ribeirinha sofre várias alterações e aterros progressivos que irão corresponder a um avanço artificial desta linha de costa. Salientam-se a construção das muralhas da frente ribeirinha no final da Idade Média, a construção do Paço da Ribeira e do Terreiro do Paço durante o século XVI e a reconstrução pombalina da Baixa de Lisboa após o sismo de 1755. O conhecimento atual relativamente à localização e tipologia dos sítios arqueológicos com achados atribuídos ao Período Romano, ao urbanismo e a sua evolução e a caracterização e cronologia de sedimentos recolhidos na margem norte do Tejo permite-nos delinear uma linha de costa estuarina (e traçado dos vales que entalham esta margem) entre Xabregas e Pedrouços para a época romana. O estudo continuado de todos estes elementos (particularmente os de carácter arqueológico e geológico) permitir-nos-á proceder a uma constante atualização deste traçado.info:eu-repo/semantics/publishedVersio

Luria lurida (Gastropoda), a new record for the Pleistocene of Santa Maria, Azores

The cypraeid gastropod Luria lurida (Linnaeus, 1758) is reported for the first time from Pleistocene deposits at the Prainha site, on the island of Santa Maria, Azores archipelago

Arouca Geopark: geotourists are arriving!

The Arouca Geopark, located in the Aveiro district (northern Portugal), originated in 2005 and was formally established in late 2007, under the auspices of Arouca's Municipal Chamber. This ongoing project will soon be submitted to the European and Global Geoparks Networks, making it the second Portuguese geopark inside these networks. During the last three years, an international multidisciplinary team has been working on the rich geodiversity of the area, promoting the inventory and characterization of 36 geological sites, together with the identification of biological and cultural heritage (archaeology, history, ethnography, gastronomy) which are necessary to fulfil the geopark requirements. The link with educational and tourist activities is also progressing, aiming the sustainable development of the region. Among the 36 geological sites subject to preliminary studies and already accessible, two of them are of special international relevance: the Canelas Slate Quarry and its on-site Museum, and the Castanheira Nodular Granite, with a place popularly known as pedras parideiras (= "the stones that give birth", or rather "rocks delivering stones"). The first is an outstanding fossil locality of Darriwilian (Middle Ordovician) age, where giant trilobites (up to 70 cm in size) and trilobite clusters (from several to thousands of specimens) occur in large slabs of shale, recovered during roofing slate quarrying. The Valerio & Figueiredo private company encourages scientific access to its quarry and has built an on-site museum to preserve and disseminate knowledge about trilobites and the Ordovician world. The Geological Interpretation Centre of Canelas, located near the quarry and open since 2006, is one of the main tourist attractions of the Arouca Geopark, having received more than 10,000 visitors in 2007. The Castanheira Granite is a small and very peculiar granite outcrop that contains a remarkable abundance of discoidal biotite nodules ranging from 1−12 cm in diameter, now protected by the Arouca municipality and visited by 15,000 persons during the last year. A popular legend attributes magical properties to these nodules in terms of female fertility, since these dark mineral lumps pop out spontaneously from a creamy-coloured matrix due to differential dilatation during the hot summers. A new interpretation centre will be established in 2008, using an old house close to the outcrop: the "House of Rocks Delivering Stones". The present work is being performed under the project "Identification, Characterization and Conservation of Geological Heritage: a Geoconservation strategy for Portugal" sponsored by the Portuguese Foundation of Science and Technology (PTDC/CTEGEX/64966/2006, years 2007-2009), and is also part of the PATRIORSI project of the Spanish Ministry of Education and Science (CGL2006- 07628/BTE, years 2006-2009)

Paleoenvironmental evolution of estuarine systems during the last 14000 years - the case of Douro Estuary (NW Portugal)

Proceedings of the 8th International Coastal Symposium, ICS 2004, Itajaí/Itapema, Santa Catarina, Brazil, 14 to 19 March 200

On the rise and fall of oceanic islands:Towards a global theory following the pioneering studies of Charles Darwin and James Dwight Dana

The careers of Charles Darwin (1809–1882) and James Dwight Dana (1813–1895) are intimately linked to circumnavigations of the globe with the British mapping expedition on the H.M.S. Beagle (1831–1836) under Captain Robert FitzRoy and the United States Exploring Expedition (1838–1842) under Lieutenant Charles Wilkes. The former expedition mainly surveyed coastal South America, but also visited many volcanic islands in the Atlantic, Pacific, and Indian oceans. The latter expedition followed a similar path through the Atlantic, but devoted more time to Pacific Ocean islands. Remembered more today for his visit to the Galapagos Islands and its subsequent impact on understanding the mechanisms of biological evolution, Darwin was motivated early on during his stopover in the Cape Verde Islands to compile studies on the geology of volcanic islands. Better known for his theory of atoll development from the subsidence of volcanic islands stimulated by his visit to the Keeling Islands and published in 1842, Darwin also wrote a related volume published in 1844 with an equally strong emphasis on island uplift. Dana was influenced by Darwin's theory of atoll development, and published his own independent observations on coral reefs and island subsidence in 1843, 1849, and 1853. The work of both geologists matured from primary observations using inductive logic during fieldwork (i.g. unconformable position of limestone on and between basalt flows as an indicator of paleo-sea level) to the advancement of broader theories regarding the behavior of the Earth's oceanic crust. Notably, Dana recognized age differences among islands in Pacific archipelagos and was strongly influenced by the orientations of those island groups. The classic Hawaiian model that features a linear string of progressively older and subsiding islands does not apply easily to many other island groups such as the Galapagos, Azores, Canary, and Cape Verde islands. Geologists and coastal geomorphologists increasingly find that the original observations on island uplift covered in Darwin's, 1844 treatment provide an alternative pathway to understanding the complexities of island histories in oceanic settings. Original work by Darwin and Dana also led to ongoing studies on the trans-oceanic migrations of marine organisms, such as barnacles, corals and non-attached coralline red algae represented by rhodoliths. This work gives added importance to oceanic islands as way stations in the dispersal of biotas over time.</p