Pedro Cunha

This paper focuses on slope dynamics in schist/slate materials in cold humid environments. It characterises the sedimentological features and controls involved in the formation of stratified slope deposits in two areas with similar topographical, lithological and climatic characteristics. In both areas, the slopes have dips >30º and the dominant rock types are schists and slates. In the case of Tierra del Fuego, the sedimentary deposits studied are modern; those in Galicia are Pleistocene in age. The slope processes operating in Tierra del Fuego, generating modern stratified slope sedimentary deposits, throw light upon the interpretation of similar ancient sediments studied in Galicia. This comparative study reveals the fundamental role played by snow and freeze-thaw cycles in the creation of stratified slope deposits. Firstly, snow cover has a direct effect on the slope, compacting sediments, keeping ground temperature stable during winter, or moving clasts as they slip down the slope or act as a slide ramp. Indirectly, as the snow melts, it creates surface runoff and mud or gravel slides. Secondly, the activity generated by numerous freeze-thaw cycles results in the vertical mobility of clasts. However, the continuous loading of sediments on the slope hinders the formation of coarse-grained pavement. Thirdly, the rock type and slope steepness play an important role in the creation of stratified slope deposits.

Oral: Anthropic interference versus littoral dynamics: Aguda (Northern Portugal) breakwater, Holocene
evolution and recent coastal erosion
Poster: S. Paio (Labruge, Vila do Conde, Northern Portugal). A protected area and its geomorphologic value

RESUMO Palavras-chave: Cenozóico; estratigrafia; sedimentologia; depósitos fluviais; análise de bacias; paleogeografia, neotectónica; Portugal. Apresenta-se uma interpretação paleogeográfica e tectono-sedimentar do norte de Portugal, tendo em conta estudos anteriores (geomorfologia, litostratigrafia, mineralogia, sedimentologia, paleontologia, etc.). O Cenozóico apresenta características distintas de acordo com o seu enquadramento morfotectónico na região oriental (Trás-os-Montes) ou próximo da costa atlântica (região ocidental, áreas do Minho e Douro Litoral). Na região oriental o registo sedimentar é considerado Neogénico, mas localmente identificou-se Paleogénico (?). Este registo mais antigo, representado por depósitos aluviais, foi preservado da completa erosão devido à sua posição no interior de fossas na zona de falha Bragança-Vilariça-Manteigas. Os episódios sedimentares seguintes (Tortoniano superior-Zancliano ?), representados por duas unidades alostratigráficas, foram interpretados como sistemas fluviais entrançados de uma rede hidrográfica endorreica, drenando para a Bacia Terciária do Douro (para leste, em Espanha); actualmente, ainda se conservam em depressões tectónicas e em vales fluviais escavados no soco. Posteriormente, a sedimentação a oriente torna-se mais escassa pois sistemas fluviais atlânticos (ex. o pre-Douro) capturaram, sucessivamente, anteriores drenagens endorreicas. O sector proximal da unidade alostratigráfica atribuída ao Placenciano está registado em Mirandela (Trás-os-Montes) mas o episódio fluvial seguinte (Gelasiano-Plistocénico inferior ?) já se documenta mais para oriente, conservado em altas plataformas e em depressões tectónicas. Na zona costeira ocidental, o registo sedimentar é atribuível ao Placenciano e ao Quaternário e está principalmente representado por terraços; localiza-se no interior dos largos vales fluviais dos rios Minho, Lima, Cávado e Ave, bem como em Alvarães e na plataforma litoral do Porto. Os episódios sedimentares terciários do norte de Portugal foram principalmente controlados pela tectónica, mas posteriormente (Placenciano-Quaternário) também pelo eustatismo.

Archaeological evidence for the earliest human presence in western Iberia is summarised and discussed.
Western Iberia is geologically characterised by magmatic and metamorphic rocks (Hesperian Massif) but also by siliciclastic and carbonate Mesozoic and Cenozoic formations. The geological context affects the distribution of Pleistocene archaeological sites, as the most of the archaeological evidence known today is located in river terrace formations or in karst deposits. Very few sites have been fully investigated; the older ones are tentatively dated as middle/late Middle Pleistocene. Recent results have been obtained using an archaeological and geomorphological approach carried out in the Portuguese region of Alto Ribatejo. Dating of the lithic assemblages found in fluvial terraces or in cave deposits indicates that the first human presence in Portugal is not older than the OIS 8–9. However, it remains difficult to explain
the long chronological gap between the archaeological evidences in western Iberia and the older sites in central and eastern Iberia, such as those in the Sierra de Atapuerca and Guadix Baxa areas.

We present the results of K-feldspar IRSL dating of the four lower terraces (T3–T6) of the Portuguese Tejo River, in the Arripiado-Chamusca area. Terrace correlation was based upon: a) analysis of aerial photographs, geomorphological mapping and field topographic survey; b) sedimentology of the deposits; and c) luminescence dating. Sediment sampled for luminescence dating gave unusually high dose rates, of between

ABSTRACT Mapping of clay resources in the Cenozoic deposits of the Tábua region (central Portugal) has been carried out, together with the chemical, mineralogical and technological characterization of seventeen clay samples. The study was undertaken to relate the lithostratigraphic units and the typology of raw materials with regard to the manufacture of ceramics. The sedimentary succession comprises two units with different suitability for the manufacture of ceramics: an upper unit, with clays that present technological restrictions; and a lower unit with a much greater potential. A small set of parameters has been identified which differentiate the typological units. These parameters allow a realistic estimation to be made of the ceramic properties of any clay layer sampled in the study area. It is anticipated that with minor field work and sampling, the typological column can also be used in adjacent areas.

RESUMEN Se presentan los primeros resultados de los proyectos de investigación dirigidos al análisis cronoestratigráfico de las terrazas del río Tajo en el entorno de Toledo. El análisis se ha centrado en niveles fluviales del Pleistoceno Medio y Superior con yacimientos paleontológicos y achelenses con valoración tecnológica general similar al conjunto lítico de Pinedo (colección Máximo Martín Aguado). En el presente trabajo se incluyen las dataciones por ISRL y AAR de los niveles de terraza de +25-30 m que contienen los yacimientos achelenses de Pinedo y Cien Fanegas. Las edades ISRL obtenidas (>280 ka y 292 ± 17 ka) indican que la terraza y los yacimientos que contienen se formaron durante los estadios isotópicos MIS 9 y MIS 8, siendo correlacionables con la Unidad Arganda II en el valle del Jarama, aunque Pinedo podría representar parcialmente a la Unidad inferior de Arganda I (MIS 11 – MIS 9). La datación AAR obtenida para la Unidad superior de Pinedo indica una edad de 226 ± 37 ka. Aunque esta edad ha de tomarse con precauciones debido a la escasa contextualización estratigráfica y los bajos niveles de dentina de las muestras analizadas, podría indicar que el depósito de la terraza estudiada se continuó hasta bien entrado el MIS 7, como también parece suceder en el Jarama (Valdocarros). En el tramo del valle analizado los procesos de sobre-sedimentación ligados a los fenómenos de subsidencia evaporítica (aguas arriba) y la existencia del nivel de base interno impuesto por el meandro encajado de Toledo (aguas abajo), favorecieron los procesos de agradación fluvial sobre los de encajamiento. El método de datación utilizado (post IR–IRSL) ha permitido obtener la edad más antigua hasta la fecha sobre sedimentos fluviales arenosos en la Cuenca del Tajo. Palabras clave: Geocronología, OSL-IRSL, AAR, terrazas fluviales, Achelense, Valle del Tajo, España Central. ABSTRACT This study presents the first geochronological data from research projects focused in the chronostratigraphy of the Tagus fluvial terraces in the environs of Toledo (Central Spain). The research is focused on Middle to Late Pleistocene fluvial terraces with palaeontological and acheulean sites of similar palaeolithic technology than those showed by the lithic assemblage of the Pinedo site (Máximo Martín Aguado Collection). This study includes first ISRL and AAR dating for the fluvial levels at +25-30 m containing the acheulean sites of Pinedo (Toledo) and Cien Fanegas (Aranjuez). The obtained ISRL dates (>280 ky and 292 ± 17 ky) indicate that this fluvial level and their inset palaeolithic sites formed during the marine isotopic stages MIS 9 y MIS 8, being possible to correlate them with the Arganda II Unit of the adjacent Jarama valley. However, data from Pinedo suggest that this acheulean site will also correspond to the lower Arganda I Unit of the Jarama valley (MIS 11 – MIS 9). In spite of the obtained AAR date (226 ± 37 ky) has to be carefully considered, due to the scarce stratigraphic data and low dentine levels of the Equus sp. analyzed samples, it will indicates that sedimentation of the studied terrace level reached the MIS 7, as may also occur in the Jarama valley (Valdocarros). The analyzed sector of the Tagus valley, continuous fluvial sedimentation was favored by the occurrence of karstic evaporitic subsidence (upstream) and the presence of an outstanding internal base-level represented by the Toledo Rocky Meander (downstream). The dating method used in this study (post-IR IRSL) let to obtain the oldest date at present from fluvial sandy deposits in the Tagus fluvial basin. Keywords: Geochronology, OSL-IRSL, AAR, fluvial terraces, Acheulean, Tagus Valley, Central Spain.

Novos dados sobre a Pré-história da zona do Cabo Espichel (Sesimbra, Setúbal), em resultado de vários anos de investigação, incluindo prospeções de natureza arqueológica, geoarqueologica e paleontológica e trabalhos de escavação pontual. Os autores incluem ainda observações sobre a fauna recolhida num concheiro e sobre estudo palinológico de cinco amostras sedimentares.

The burial age of an alluvially deposited cobble pavement at the Tapada do Montinho archaeological site (east-central Portugal) is investigated using optically stimulated luminescence (OSL) dating. Measurements on the cobbles (quartzite clasts) were carried out on intact slices and large aliquots (∼8 mm) of quartz grains (63–300 μm), both recovered from the outer 1.5-mm surface of the cobbles. The recycling ratio, recuperation and dose-recovery tests show that the single-aliquot regenerative-dose (SAR) protocol is applicable to both rock slices and quartz grains; both have similar luminescence characteristics. The variation in the natural OSL signal with depth below the cobble surface using intact slices from two different cobbles shows that both were bleached to a depth of at least ∼2 mm before deposition. A model of the variation of dose with depth fitted to data from one of the cobbles gives a burial age of ∼19 ka and also predicts the dose-depth variation at the time of deposition. Ages based on rock slices suggest that one cobble surface, and the inner parts of two other cobbles experienced a resetting event at ∼45 ka, consistent with the age control. However, the surfaces of the other cobbles all record light-exposure events in the range 26 to 14 ka, suggesting that some of the cobbles were exposed to daylight perhaps more than once in this period. Given the shallow burial depth and unexpectedly young ages of the surrounding and overlying finer-grained sediment, it is suggested that phases of light exposure following surficial erosion are probably responsible for this underestimate. Nevertheless, it is remarkable that we can identify and quantify four events (two light exposures of different durations and two sequential burial periods) in the dose record contained within a single clast, and this suggests that the luminescence dating of rock surfaces may prove, in the future, to be at least as important as sand/silt sediment dating.

Tectonic displacements affecting the culminant sedimentary unit (probable Late Pliocene to lowermost Pleistocene) of the Lower Tejo Basin are common. Using geomorphologic and stratigraphic references, these vertical displacements can reach up to 70 m. There are geomorphologic evidences that the faults have been active during the Pleistocene, displacing the terraces, whose ages are known in the lower ones (Martins, et al., 2010). However, faulted surfaces affecting terrace deposits have been very difficult to found and are often considered unreliable. This seems strange because a staircase of six terrace levels (T1 to T6, from the upper to the lower), indicating a long-term uplift during the Pleistocene, is present. Several depositional episodes related to the evolution of Tejo River were identified: the culminant sedimentary unit (P-sandstones and conglomerates) of the sedimentary basin, deposited just before the beginning of the incision stage of the drainage network; T1 terrace (conglomerates); T2 terrace (conglomerates); T3 terrace (conglomerates); T4 terrace (conglomerates and sandy at top); T5 terrace (gravels and sands); T6 terrace (gravels and a sandy-muddy at top); H-Holocene valley infill (gravel base and sandy at top). Terrace correlation was based upon: a) aerial photograph analysis, geomorphological mapping and field topographic survey; b) K-feldspar infrared stimulated luminescence (IRSL) dating of the lower terraces, as quartz optically stimulated (OSL) signal of the samples from these terraces was close to saturation in almost all samples. The IRSL dating also included a correction for anomalous fading. The ages of the two upper terraces (T1 and T2) are beyond the upper range of the dating method. The T3 terrace is much older than 300 ka (minimum age), T4 is < 340 to 150 ka, T5 is 136-75 ka, and the T6 is 60 – 30 ka. Using the age of the T4 surface, for the last 150 ka a time-averaged incision rate was quantified as ~0.35 m/ka in the more uplifted block of the valley (east of Chamusca town) and ~0.13m/ka in the west side of the valley. For the reach III (Abrantes area) the time-averaged incision rate was quantified as 0,25 m/ka. If we consider the beginning of the incision stage of the Tejo River coeval with the depositional surface of the Spanish alluvial fans (raña of Sierra Morena Central), dated as ~1.7 Ma (Escudero & Olmo, 1997), in a similar geomorphologic position as the culminant sedimentary unit of the Lower Tejo Basin, then the ages of the surfaces of the T1 terrace could be ~850 to 970 ka and the T2 ~600 to 670 ka, using an interpolation considering the luminescence ages of the younger terraces. If that is true, the incision rate seems to be faster in recent times. Long-term fluvial incision appears to have been controlled by regional uplift but the interplay of eustatic and climate controls could have played the main role in the episodes of dynamic equilibrium and aggradation.

Resumo Apresenta-se uma síntese da caracterização sedimentológica e hidrodinâmica actual dos sub-sistemas do Estuário do Mondego. Os dados foram obtidos pelo registo de parâmetros hidrodinâmicos e físico-químicos (salinidade, temperatura, velocidade e orientação das correntes, turbidez, concentração de silte/argila, pH e Eh), ao longo de perfis longitudinais, de 1994 a 1996; para além da obtenção de uma pormenorizada carta de sedimentos, o estudo sedimentológico incluiu uma abundante amostragem de sedimentos superficiais para a determinação laboratorial da granulometria, mineralogia e morfoscopia. Discute-se a circulação sedimentar na área estuarina e a influência relativa dos controles sedimentares.

In the Lusitanian Basin (western Iberian margin), the upper Aptian-lower Campanian stratigraphic record (unconformity-bounded unit UBS4) consists of non-marine siliciclastics interfingering with platform carbonates. Its lower boundary (the breakup unconformity) is a truncation over the Mesozoic (with karstification) and the Hercynian basement; onlap exists in the NE border. Biostratigraphy and palaeobiology of the marine/transitional facies and sedimentologic studies allowed detailed palaeogeographic reconstruction and assessment of the sedimentary controls balance. Within the long-term eustasy and thermal subsidence, the sequential evolution is controlled by short-term eustasy, minor tectonics (including halokinesis) and possible intraplate stress changes. The west Galicia breakup (late Aptian) generated thermal and isostatic uplift of the northeastern Hesperian Massif, inducing erosion of deeply weathered granites and metamorphic rocks. Braided fluvial systems drained south-westwards into deltaic systems connected with a carbonate platform. Long-term Albian-Cenomanian transgression allowed the widespread deposition of carbonates, initiated by tidal flat/lagoon sandy marls and limestones followed by shelf limestones with ammonites (transgression maximum) and subsequent regressive facies with rudist and coral buildups. A long-term sea-level fall resulted in progradation of the depositional systems and later fluvial incision (reaching 100m at the NE of the basin). A well developed silcrete occurs at the top of the siliciclastic record, indicating a long subtropical weathering (early Campanian ?).

Desde os primórdios da civilização humana, há cerca de 4000 anos, as cidades começaram a localizar-se nas margens de cursos de água. Esta escolha era principalmente favorecida pela facilidade de transporte ao longo rio e pela proximidade às melhores terras agrícolas, situadas nas férteis planícies de inundação. Contudo, as cidades localizadas nas margens de rios ficam ameaçadas por vários riscos geológicos. A migração dos canais de um rio pode prejudicar a utilização dos terrenos ribeirinhos e destruir pontes, principalmente quando estas estejam fundadas nas aluviões. Embora de rara ocorrência e curta duração, as situações de cheia são, frequentemente, responsáveis por significativas alterações nas características geomorfológicas do sistema sedimentar, podendo desencadear a avulsão. O transbordo, provocando o alagamento da planície de inundação, não ocorre necessáriamente todos os anos mas constitui um processo natural comum a todos os cursos de água não regularizados. A erosão causada pelas cheias pode ser pouco prejudicial numa planície de inundação não habitada, mas pode destruir construções e vias de comunicação de uma cidade ribeirinha. Em outros casos, os eventos de cheia provocam uma indesejável deposição de sedimentos, difíceis de remover. Chuvas concentradas e prolongadas são as causas naturais mais vulgares das cheias. A intervenção humana também pode contribuir para aumentar os efeitos das cheias. Os extensos pavimentos das áreas urbanizadas promovem o escoamento ao invés da infiltração. Por outro lado, as linhas de água naturais tendem a ser substituídas por condutas artificiais de reduzida secção, mais susceptíveis a entupimentos e de difícil manutenção. Também as frequentes estruturas implantadas nos canais activos e nas planícies de inundação — tais como pilares de pontes ou viadutos, muros e edifícios — podem constringir fortemente o fluxo de cheia, provocando uma rápida subida do nível de água e aumentando a velocidade da corrente, o que promove a erosão local.

Created by the break-up of Pangea, the Lusitanian Basin is located in the western margin of Iberia. It corresponds to a complex NNE graben (including several half-grabens) located between the Hercynian mainland and a set of basement horsts. The goal of this work is to present an updated lithostratigraphy of the Cretaceous sedimentary record and its 2 nd order Transgressive-Regressive cycles separated by basinwide unconformities, deposited in a post-rifting context following the Oxfordian-Kimmeridgian extensional phase. South of the Caldas da Rainha parallel a domain with a more complete Berriasian/middle Cenomanian record has its depocenter in the Lisbon peninsula. The northern sector has a Valanginian/Aptian p.p. hiatus, but a better or exclusive upper Cenomanian to Maastrichtian record. We admit that the main unconformities can be related to 2 nd order eustatic cycles and/or discrete episodes of the counterclockwise motion of Iberia, in particular the northward progress, until the Aptian, of continental break-up along the three sectors of the western Iberian margin (Galicia, Iberia and Tagus). Later, the break-up followed along the Bay of Biscay.

RESUMO Efectuou-se uma avaliação das variações batimétricas e taxas sedimentares relativas ao período de Fevereiro de 2002 a Agosto 2003 no sector portuário do estuário do Mondego, mais concretamente a entrada da barra e anteporto. Na análise foram tidas em conta as características da agitação marítima (rumo, altura e período da ondulação) e acções antrópicas (dragagens) durante o período de monitorização. Seguiu-se a metodologia descrita por Mendes (2002), que monitorizou a mesma área de Março de 2000 até Novembro de 2001. Este tipo de análise complementa a que foi feita para períodos mais alargados (e.g. Cunha & Mendes, 2000). Os dados da ondulação foram obtidos pela Capitania do Porto da Figueira da Foz, por estimativa visual a partir do farol do Cabo Mondego; os registos foram efectuados duas vezes por dia, às 9h e às 16h, tendo a média diária sido utilizada neste estudo. Os dados referentes às dragagens e cartas topo-hidrográficas na escala 1/2000 foram disponibilizados pelo Instituto Portuário e dos Transportes Marítimos – Delegação dos Portos do Centro (IPTM-DPC). As sucessivas cartas topo-hidrográficas foram analisadas com o recurso a um Sistema de Informação Geográfica (SIG), o ArcView 3.2, calculando-se taxas de assoreamento ou de erosão para a área anteriormente referida. Esta análise permitiu também uma descrição da evolução morfossedimentar e interpretar as causas dessas modificações. As cartas topo-hidrográficas foram representadas numa perspectiva tridimensional, tendo-se atribuído aos molhes portuários a cota de 4 m acima do Zero Hidrográfico. Cada uma destas representações representa um momento na evolução batimétrica de um dado sector. Utilizando o ArcView, obtiveram-se mapas de diferença batimétrica entre campanhas consecutivas e compreendendo uma dada área. Este método foi particularmente útil para identificar sectores onde ocorreu aprofundamento ou elevação topográfica para um dado intervalo temporal entre levantamentos, calculando o respectivo volume. Cada volume obtido, positivo (assoreamento) ou negativo (erosão), foi dividido pela respectiva área, para se obter a variação média em espessura. Dividindo esse valor pelo número de dias do período considerado, obteve-se o valor médio diário de variação batimétrica. As cartas de diferença batimétrica foram interpretadas tendo em conta as características da agitação marítima, bem como os volumes e locais das dragagens, referentes a cada período. Descreveu-se a evolução das variações sedimentares na zona que compreende o anteporto e entrada da barra, enquadrando com as respectivas condições de agitação marítima. Para tal aplicou-se o método anteriormente referido apenas ao polígono de 204289 m 2 utilizado por Mendes (2002), figura 1, por forma a se poder prolongar o período de monitorização de uma mesma área. Foram calculadas as taxas de variação batimétrica média diária, bem como as taxas sedimentares médias diárias (que também incluem os volumes dragados). No período monitorizado existiu uma muito fraca tendência positiva para o assoreamento ocorrer com o decréscimo da altura média, com o aumento do rumo (rotação de W para NW) e com o aumento do período da agitação marítima.

The morphology of the Portuguese mainland is characterized by erosional plateaus elevated to different heights, cut on metasedimentary rocks and granites of the Palaeo-zoic Hesperian Massif. The relief distribution (43% in area below 200 m, 30% above 400 m, and only 0.5% above 1200 m) reflects the amplitude of the vertical movements. About 95% of the areas above 400 m of altitude are located in the northern and central parts of the country. In the central region, uplift was the greatest, rising the Portuguese Central Range to a maximum elevation of nearly 2000 m. This ENE-WSW trending mountain chain is roughly aligned with the Spanish Central System. Although difficult to age precisely, the vertical movements are reasonably well characterized mainly by geomorphologic criteria and through the study of the Mesozoic and Cenozoic sedimentary record. During Cretaceous times, the western sector of the Hesperian Massif, as for much of Iberia, had a relatively low and gentle topography close to sea level. Interplate interaction at the Pyrenean and Betic collision zones, during Eocene-Oligocene and Miocene times respectively, originated intraplate com-pressive stresses which acted upon cratonic Iberia reactivating major Late-Variscan faults. By middle Eocene times, significant uplift had occurred in N Iberia and two SW-NE elongated grabens (Mondego and Lower Tagus Tertiary basins) start to open, symmetrically with the opening of the Spanish Douro and Madrid Tertiary basins. This was coeval with the tectonic inversion of the Mesozoic rifted Algarve basin, located at the SW border of Iberia. In the Miocene, compression was intensified causing inversion of the Mesozoic Lusitanian basin at the W. It also generated NE-SW trend-ing upthrust basement blocks and related fore-deep basins, as the Portuguese Central Range/Western Mountains and the correlative piedmont basins, as well as push-up blocks and pull-apart basins along strike-slip faults zones trending NNE-SSW. Gentle

RESUMO A erosão hídrica dos solos é um fenómeno resultante de factores naturais ou antrópicos, que influencia a dinâmica das paisagens e dos ecossistemas. A compreensão dos factores e processos que condicionam a erosão hídrica é crucial para o planeamento de medidas de conservação do solo. O escoamento superficial e o transporte sólido a ele associado vêm sendo estudados principalmente devido aos seus impactes na agricultura e no dimensionamento e gestão de infra-estruturas hidráulicas. Vários autores têm referido a existência de alterações no escoamento superficial gerado por frentes móveis de precipitação atmosférica, relativamente às que são observadas quando a precipitação é estática. Entre outras, existem variações nos

Several studies have demonstrated that the volume and characteristics of sediments generated by a moving rainfall are dependent on storm movement in relation to the land surface. This study aims to describe and interpret the grain-size distribution of sediments generated during experimental simulations on a soil flume subjected to downstream and upstream moving storms. Storms were generated by moving a rain simulator, at a constant speed, in the upstream and downstream directions along a soil flume. The sediments transported by overland flow were collected at the flume outlet. Sediment grain-size distribution was obtained by conventional sieving and laser diffraction, using a Coulter LS 320. The pattern of sediment grain-size evolution depends on the direction of storm movement. For downstream-moving storms a good relationship between discharge (and, consequently, stream power) and mean sediment size was found. However, as the

Santiago Island is one of the ten islands of Cape Verde Archipelago. This archipelago is located on the central Atlantic Ocean at about 10º to 16ºN, 22º to 24ºW, and belongs to a major group of Atlantic islands, the Macaronesian Islands, which includes Azores, Madeira and Canary islands. The Cape Verde islands are rooted on an uplifted domain of oceanic crust (Cape Verde Swell) and are associated to intra-plate volcanic processes, which started about 60 Ma ago and still proceed nowadays. The tectonic setting of Cape Verde Archipelago is complex and several interpretations were published. However, geographic, geologic, tectonic and geomorphological regional evidences points to the interference of: (1) MAR transformation faults, (2) important uplifting processes and (3) regional main NW-SE and NNE-SSW tectonic structures. Santiago Island is the biggest island of the Archipelago (991 km 2) and is elongated NNW-SSE. The volcanic stratigraphy includes: (1) an older Volcanic Complex associated to proto-insular and submarine volcanism and (2) a sequence of volcanic formations and complexes dominated by subaerial volcanic events. Basaltic volcanics predominate, which are represented by lava-flows, pyroclast deposits, volcanic dikes and necks. Phonolithic and trachytic rocks outcrops less extensively. There are strong evidences of important uplift events during the island geotectonic evolution.

Papel desempeñado por la tectónica, el clima y el eustatismo en la génesis de los depósitos de Raña al pie de la Cordillera Central Portuguesa (Iberia occidental) Role played by tectonism, climate and eustasy during the genesis of the Raña deposits along the piedmonts of the Portuguese Central Range (western Iberia)

Fluvial sequences results from cyclic imbalance between sediment supply to stream power. In most of the conceptual approaches sequence boundaries are traced using the sedimentary record of episodes of disequilibrium towards more energy (steepening average gradient). This can be produced by upstream uplift, increased downstream subsidence, base-level drop or climatic-driven changes in loading index (increased upstream erosion and alluvial sediment load). Strictly, a cycle implies a shift from an initial condition to an opposite extreme and back to the initial condition. In this sense, all allogenic controls-and consequently the resulting stratigraphic record-can be considered as cyclic: high-low-high, active-quiet-active, wet-dry-wet, cold-hot-cold, etc. Even if reflecting the interplay between those drivers, probably each with a different timing and intensity, the large-scale architecture can be interpreted as a shift between opposite combinations. After a disequilibrium episode a clastic wave progrades downstream trying to reach the (steeper) graded profile. However, even if allogenic controls become steady, autogenic behaviour results in downstream aggradation and upstream erosion-fluvial grade is dynamically adapting to decreasing energy, with gentler and longer profiles. Hence, little accommodation is available resulting in progradation and limited aggradation. So, whatever driver dominates, a pattern of alluvial depositional architecture emerges: i) lower progradational package (LPP), ii) aggradational to retrogradational package (ARP), iii) upper progradational package (UPP). In a sequence stratigraphic model those volumes are separated by surfaces: i) sequence boundary surface (SBS, even if sometimes cryptic, it corresponds to change from aggradation to degradation), ii) maximum progradation surface (MPS, separating LPP from ARP) and maximum retrogradation surface (MRS, separating ARP from UPP). Note that MPS and MRS are more conceptual than physical in continental settings. The existence of fluvial terraces, in particular staircase complexes, implies a context of long-term incision trend with episodes of incision in successively narrower active alluvial belts, separated by minor aggradational episodes. The 3D infill of an incised valley is a combination of upstream migration of the erosion/deposition nickpoint (between positive and negative accommodation) and transversal onlap over valley margins. This result in a physical separation between LPP, restricted to the incised valley (buried, or eroded in the long-term evolution), and a wider and probably thinner UPP partially preserved and exposed as part of the terraces staircase.

Bottom sediments in river-estuarine environments record prevalent conditions, like dynamics, sediment sources and pathways. In this work we test several textural features that can be used to estimate such environmental conditions. As the data was collected along a straight channel with homogeneous slope, conditions related to local geomorphic particularities are expected to be minimal. The main factors that determined the textural features of the deposits are the source sediments features and the dynamic conditions (primarily fluvial discharge and tidal cycle characteristics). It is demonstrated that mean sediment size, although one of the most common statistical parameter used to characterise a grain-size distribution, may not be a useful parameter in the estimation of hydrodynamic conditions. In estuarine channel sediments the grain-size distribution frequently comprises a mixture of at least two populations, deposited during the ebb and flood periods or spring and neap cycles, being the conditions of reduced hydrodynamics probably responsible for finer populations. As evaluation of the dynamics requires that a single sediment transport unit is analysed, a problem also arises from the sampling procedure. When a dredge is used it is not possible to ensure that just the uppermost sediment level is sampled and the collected sediments may comprise levels from several depositional events. The sediment mixture will be responsible for a bias in the grain-size distribution attributes. To minimize misinterpretations, the possible constituent populations of the grain-size distributions must be discriminated. This can be approximated by simple visual analysis and identification of modes and classification of the grain-size distributions. The discrimination of populations may give valuable information on the prevalent depositional conditions. Sediments in estuarine channel were found to be deposited in contrasting dynamic conditions, involving periods of higher energy than in the fluvial channels upstream. Combined grain-size and particle rounding data may be used to confirm these populations. Differences in roundness of coarser and finer fractions tend to be smaller in sediments that result from mixtures of coastal (beach, spit or dune) and fluvial derived populations. A combination of this set of data may also be used to trace sediment paths.

The Lower Tagus Valley (LTV) is located in the central-western zone of Portugal mainland and comprises the densely populated and highly developed area of Lisbon. Earthquakes that caused severe damage and many casualties have affected this region, making seismic hazard evaluation a major regional issue. Regional seismicity includes relatively distant events, as the 1755 earthquake (M 8.5), generated in the broad deformation zone of the Eurasia-Africa plate boundary. The study region also experiences a significant local seismicity, with M=6-7 historical intraplate earthquakes, as in 1344, 1531 and 1909. Since 1909, seismic activity in the study area has been low and diffuse, with only a few magnitude 3-4 earthquakes. Although the LTV has been the subject of several studies on neotectonics, major uncertainties concerning the seismogenic structures persist due to the low slip rates and the presence of a thick sedimentary cover that conceals the faults in the underlying basement. The LTV is sited in the Lower Tagus Basin, a NE-SW elongated tectonic depression comprising up to ca. 2000m of Cenozoic sediments, located at the eastern border of the Mesozoic Lusitanian Basin. It was developed since the Eocene, with a major evolving phase in the Neogene as a transpressive foredeep related to tectonic inversion of the Lusitanian Basin, due to a NW-SE Miocene compression. Regional seismicity has been poorly monitored until 1995, preventing a reliable location for most of the prior events. The low instrumental seismicity, depth and poor location of the earthquakes mask their relationship to the faults recognized at the surface. It is often assumed that a so-called Lower Tagus Valley Fault generates the regional large events. Not withstanding the existence of a macro-scale, NNE-SSW trending, wide fault zone in the basement, no evidence was found for the presence of such a continuous structure at the upper crustal levels. Instead, what gravimetric, seismic reflection, geomorphologic and surface geology data indicate is a segmented regional fault system, with NNE-SSW en echelon faults presenting Neogene vertical offsets (mostly high angle reverse), linked by WNW-ESE faults probably working as transfer zones which also accommodate significant vertical offsets. Evidence of Quaternary tectonic activity was found for some of these structures. The faults range in length from 10 to 40 km, being capable of individually generating maximum earthquakes of magnitude 6.2 to 6.9. These fall in the magnitude range estimated for the historical seismicity, suggesting that the historical earthquakes represent " maximum earthquakes ". Historical earthquakes in the LTV deviate from the Gutenberg-Richter relation for the weak instrumental seismicity, pointing to characteristic earthquake behaviour. This outcome may result from time clustering of the " characteristic " earthquakes, which reduces their recurrence time, due to the interaction between adjacent faults of the Lower Tagus fault system. Accordingly, M 6-7 " characteristic " earthquakes occur in clusters, where events are separated by recurrence times of the order of 10 2 years. As stress is released along the fault system, the next earthquake set probably occurs separated by recurrence times of the order of 10 3 years. This agrees with the few estimated low slip rates for regional active structures (0.1-0.05mm/yr).

Fault scarps and erosive edges are typical geomorphic elements of the Portuguese western margin. Onshore, it is common to identify a low slope coastal platform that increases elevation towards east until it ends by an important sharp relief, usually named Marginal Relief. These elevations follow Variscan tectonic directions, dominated by N-S and NNE-SSW trending structures, and define almost continuous curved reliefs, generally marked by a low mountain front sinuosity. The tectonic interpretation of the Porto-Águeda region, based on morphologic, tectonic and lithologic data, suggests a strong structural control, evidenced by the presence of fault scarps, elongated corridors, elevated or depressed sigmoidal areas, tilting of the coastal platform, anomalies in drainage patterns and differences of the fluvial incision. The morpho-tectonic characterization led to the identification of two main principal deformation zones (PDZ) that could explain the morphology of the coastal platform and adjacent inland reliefs: the Porto-Coimbra-Tomar shear-zone (FPCT) and the Angeja-Ossela-Santiago de Piães fault zone (FAOSP). The tectonic interaction of these two deformation zones was found to explain the regional relief and to be the cause for the transverse direction of the elevations that constitute the Marginal Relief. It was recognized that the coastal platform is vertically displaced by faults, up to 70 m, having the several compartments distinct geological and morphological evolutions. Detailed mapping of the Late Cenozoic sedimentary deposits and faults evidenced an intense tectonic deformation of some compartments of the coastal platform. We propose a tectonic model for this interaction, which includes the deflection of the recent sinistral movement, when FAOSP overcome the FPCT. The accommodation of the deformation along the crossing area of the two fault zones led to the formation of structural reliefs with sigmoid shape, push-up or pull-apart type and duplex structures that generally define tulip-like flower structures. All these tectonic structures controlled the evolution of the coastal platform and adjacent relieves, also exerting a strong control on the drainage development.

A multidisciplinary approach involving Geomorphology, Stratigraphy, Sedimentology and K-feldspar infrared stimulated luminescence (IRSL) dating resulted in the identification of several depositional episodes, represented in 6 terraces and modern valley infill, related to the evolution of the Tejo River in Portugal (the Lower Tejo Basin). The culminant unit of the sedimentary basin, ascribed to the Pliocene, was deposited just before the beginning of the incision stage of the drainage network. The T1 terrace is in close relationship with an extensive erosion surface developed ca 30m below the culminant sedimentary surface. The T2 terrace is poorly represented, while the T3 and T4 terraces constitute extensive geomorphic references. The T5 and T6 are the lower terraces, only represented in tectonic depressions with a soft substratum (Tertiary arkoses) and finally the Holocene valley infill. The two upper terraces (T1 and T2) are beyond the upper age range of the luminescence dating method. The T3 to T6 terraces range in age between ~350 and 24 ka. The ages of the terraces agree with their geomorphic positions and allow us to estimate tectonic vertical displacements which reach up to 50 m. Geomorphological evidence for local tectonic control of drainage arises from interpretation of asymmetric drainage patterns, fault scarps, tectonic lignments, fracture-controlled valleys, and vertical displacement of planation surfaces and terraces. The main faults controlling the Tejo River drainage are considered to be NNE-SSW and NW-SE to WNW-ESE, but NE-SW, N-S and NNW-SSE are also identified. These systems are considered to be late-Variscan faults later reactivated. Terrace formation seems to have been controlled by eustatic and climate changes superposed on a long-term regional uplift setting. Using the ages of the dated terraces, a time-averaged incision rate was quantified at ~0.42 m/ka in the more uplifted block of the Tejo River valley (east side of the Chamusca town) and at ~0.20-0.28 m/ka in adjacent areas. The incision rates of distinct reaches of the Tejo River can be used as proxies for rock-uplift rates. Assuming a steady long-term incision rate, the beginning of the incision stage in the Portuguese Tejo could be estimated at ca. 1 Ma and this is currently being tested using cosmogenic radionuclide dating.

Study of multichannel seismic profiles of the Algarve Margin (offshore Portugal, southwestern Iberia) has led to a better understanding of the role of the salt tectonics on the structural evolution. Clearly recorded since the late Cretaceous and triggered by the regional stress field that also reactivated deeply-rooted basement structures, salt tectonics were favoured by Triassic-Hettangian evaporites that acted as a detachment horizon under the thick (>1-2 km) sedimentary cover. The evaporitic structures are mainly associated with the dominant fault systems (Lopes et al., 2007). Their activity was responsible for the location of the salt withdrawal depocentres, development of depositional/erosional events, and the probable changes on the water flow distribution and related sedimentary processes. A mild halokinesis is recorded from late Campanian to Lutetian and from Aquitanian to lower Tortonian, but important halokinetic processes occurred during the two following tectono-sedimentary episodes: i) During Lutetian to Oligocene, coeval with a significant structural rearrangement, salt bodies were intruded mainly along N40º, N-S and E-W trending structures. Salt withdrawal from interdiapiric areas into these growing salt walls resulted in the formation of salt-withdrawal sub-basins with localised subsidence. The tectonic style in the Eastern Domain of this margin seems to result from both gravity gliding above a salt detachment layer and the inversion of a basement-rooted graben. We propose that the gravity gliding of the sedimentary cover was associated with uplift and tilting of the northern sector of the margin, enhanced by the inversion of previous distensive structures. Glide tectonics were responsible for the development of coeval and adjoining extensive (upslope) and compressive (downslope) domains. The extensional area is characterised by thinskinned tectonics marked by listric normal faults striking N60o and resulting in half-grabens. The contractional area is characterised by syn-sedimentary folds, showing anticlines and synclines, passing southwards into the thinskinned E-W to ENE-WSW thrust front, with salt injection along the thrust plane, and associated frontal sub-basins. This type of folds and associated thrust front might have formed along salt pinch-out. An emphasis is put here on the dominant role played by the basinward salt pinch-out in forming frontal contractional structures by increasing frictional resistance at the base of the sedimentary pile, thus preventing further basinward translation of the sediments.

Resumé En dépit de la grande ancienneté da la présence humaine dans la Péninsule Ibérique, témoignée para les sites de la Sierra de Atapuerca e du Bassin de Guadix Baza, dans la partie la plus occidentale de ce territoire les vestiges se trouvent toujours en contextes du Pléistocène Moyen, le plus souvent dans les terrasses fluviatiles. Jusqu'aux années 1980, l'allure archaïque de quelques assemblages lithiques, en faisant des comparaisons avec celles du Maroc, a permis de soulever l'hypothèse d'un très ancien peuplement de la façade atlantique occidentale de l'Ibérie. Néanmoins, les contextes de beaucoup de ces assemblages n'étaient pas fiables, et en plus il y a dans la vallée du Tage des contextes datés par OSL de la fin du Pléistocène Moyen avec des industries non tipifyables dans le cadre de l'acheuléen. En tout cas, une occupation plus tardive de ce territoire, suggéré par l'absence de donnés archéologiques antérieures au pléistocène moyen, peut être la conséquence d'une faible et intermittente recherche, soit dans les terrasses fluviatiles, soit dans les contextes calcaires e lagunaires, même si ceux-ci sont géographiquement limités. Dans le cas des formations fluviatiles il faut considérer l'érosion des dépôts plus anciens. Pour bien surmonter les problématiques des premières occupations de ce territoire est en cours un programme de recherches geo-archéologiques méthodiques en tous les contextes, qui doivent être datées systématiquement par des méthodes absolues. On présente les données disponibles, tout en discutant la limite des interprétations possibles.

This study presents the results of laboratory experiments designed to investigate the influence of moving rainfall storms on the dynamics of sediment transport by surface runoff. Experiments were carried out using a soil flume. The movement of rainfall was generated by moving a rain simulator at a constant speed in the upstream and downstream directions along the flume. The main objective of the study was to characterize, in laboratory conditions, the distribution of sediment grain-size transported by rainfall-induced overland flow and its temporal evolution. Grain-size distribution curves were constructed using conventional hand sieving and laser diffraction for overland flow and sediment deliveries collected at the flume outlet. The results of laboratory experiments show that storm movement, affecting the spatial and temporal distribution of rainfall, has a marked influence on the grain-size characteristics of sediments transported by overland flow.

This study aims to provide a luminescence chronology for Pleistocene alluvial units affected by active faulting. In Almeria region (SE Spain), the lithosphere shortening caused by the collision between African and the Iberian plates have been accommodated by a number of faults, which seem to have very low slip rates and long recurrence intervals between earthquakes. These faults are distributed over a wide zone in this region but most of them do not have reliable records of seismicity (fortunately, some of them show geomorphic tectonic features). Paleoseismology is a way to find a better understanding on the seismic history of such faults (and thus their seismic potential). The Alhama de Murcia fault, located in the eastern Betics, is one of these faults that have been studied recently. In the present study, focused on the Gõnar area, six trenches were excavated for paleoseismological purposes on different sites along this fault. The depositional architecture and the tectonic displacements of the lithostratigraphic units were characterized; the uppermost unit, very disturbed by agriculture, was not sampled. For optically stimulated luminescence (OSL) dating, 15 samples were collected from the sandy and silty layers of the units exposed in the trenches and, in the future, modern analogues (sandy to silty deposits of ephemeral braided streams) will be also sampled and measured. The quartz and the K-feldspar grains were extracted using conventional luminescence sample preparation techniques (sieving, HCl, H2O2, heavy liquid: 2.58 g/cm 3). The K-feldspar grains were etched in diluted HF (10%) for 40 min to remove surface coatings and any contribution from external alpha radiation. Luminescence measurements were performed on a Risø TL/OSL DA-15 reader, with luminescence detection through a standard blue filter combination (Schott BG39 and Corning 7-59). Small (2 mm) aliquots were mounted with silicone spray on stainless steel cups. The 250-180 um quartz extracts from the samples of the older units were found in saturation. So, as an alternative method, the K-feldspar fractions of the samples were measured using the post-IR IR signal (100 s at 225°C; detection in the blue-violet region) after the IR bleach at 50°C for 100 s. This signal first proposed by Thomsen et al. (2008) is known as the most stable signal so far which shows the least anomalous fading. For younger samples, whose quartz was not in saturation, the measured doses for quartz and feldspar were compared and the results were found quite similar. The K-feldspar De's, and respective ages, are in stratigraphy. So, this study indicates that IRSL dating using the post-IR IR signal from K-feldspar could be a reliable method for luminescence dating for the cases in which quartz could not be used as the dosimeter. E. Masana, J. J. Martínez-Díaz, J. L. Hernández-Enrile, P. Santanach, 2004. The Alhama de Murcia fault (SE Spain), a seismogenic fault in a diffuse plate boundary: Seismotectonic implications for the, Laboratory fading rates of various luminescence signals from feldspar-rich sediment extracts, 2008. Radiation Measurements 43, 1474–1486.

The three-day field excursion (8-10th September) will focus on the record of long-term drainage evolution of the Tejo River (English: Tagus (from Latin), Spanish: Tajo, French: Tage). The Tejo is a major European river system, draining a large part of the continental interior of Iberia to the Atlantic coast. It provides a long-term record of landscape evolution for SW Europe, controlled by tectonics, climate and eustatic variations over the last ~3.6 Ma (Pliocene-Recent).
The fieldtrip will start in Castelo Branco and end in Lisboa (~250 km), travelling along the Tejo valley. The itinerary and programme are given in Figs. 1a and b. Field sites in the upstream reaches will provide excellent opportunities to see: 1) the geomorphology of a spectacular river gorge where the Tejo River has cut through uplifted blocks of Palaeozoic basement; and 2) to examine and comment the sedimentology, stratigraphy, luminescence dating and archaeology of river terrace
landforms where the Tejo has incised into Tertiary deposits.
Collectively, upstream field locations will provide excellent opportunities to discuss climate and tectonic controls on this river system. Sites visited in the downstream region will focus on the Pleistocene, Holocene and historical evolution of the Tejo and its estuary, providing opportunities to discuss climate and human influences on river system dynamics.