Alberto Gomes

Resumo: O litoral de Vila Nova de Gaia, a sul da cidade do Porto, constitui um trecho geoarqueológico ímpar para o estudo da ocupação quaternária da fachada ocidental da Ibéria. Neste trabalho apresentam-se algumas características tecno-tipológicas das indústrias líticas do litoral de Vila Nova de Gaia e avançam-se hipóteses sobre os respetivos contextos cronoestratigráficos, litoestratigrágicos e geoarqueológicos. De acordo com observações mais ou menos pontuais realizadas durante as últimas três décadas sugere-se que: a) A indústria lítica mais antiga parece associar-se ao nível marinho I (20-30 m a.n.m.a.m.), podendo ter sido posteriormente remobilizada na sequência de processos coluvionares. A presença de bifaces e de machados de mão entre os artefactos identificados remete-a para o Acheulense; b) A ocorrência de bifaces muito boleados em depósitos coluvionares que recobrem o nível marinho II (10-20 m a.n.m.a.m.), sugere que o seu contexto primário terá sido o referido depósito marinho; c) na base do depósito do nível marinho III da Praia da Aguda ocorrem artefactos líticos enquadráveis no Acheulense (presença de bifaces e de machados de mão); d) nas coluviões sobre os níveis marinhos I e II existem artefactos muito eolizados – aparentemente posteriores às formações marinhas e anteriores à génese das coluviões – e artefactos sem qualquer alteração física – possivelmente coevos dos processos de coluvionamento. Aspetos técnicos e tipológicos observados nestes dois conjuntos artefactuais permitem avançar a hipótese de se relacionarem, respetivamente, com o último período glaciar (idade mínima) e com o Holocénico. Abstract: The carved lithic artefacts from the littoral of Vila Nova de Gaia: generic characterization, geoarchaeological contextualization, problems and perspectives The coast of Vila Nova de Gaia, south of the city of Porto, constitutes a unique geoarchaeological stretch for the study of the quaternary occupation of the western facade of Iberia. This work presents some techno-typological characteristics of the lithic industries from Vila Nova de Gaia coastline and hypotheses concerning their chronostratigraphic context are presented. According to general observations carried out during the last three decades it is suggested that: a) The earliest lithic industry seems to be associated with marine level I (20-30 a.s.l.); however, it may have been subsequently remobilized by colluvial processes. The presence of handaxes and cleavers among the artefacts connect this assemblage with the Acheulean; b) The presence of rolled handaxes in colluvial deposits overlying marine level II (10-20 m a.s.l.) suggests that their primary context may have been the mentioned marine level; c) At the bottom of the marine level III deposit from Praia da Aguda (< 10 m a.s.l) there are lithics of Acheulean age (presence of handaxes and cleavers); d) In the colluvial deposits overlying marine levels I and II there are lithic artefacts with a very high degree of aeolisation – apparently younger than the marine formations and older than the colluvial processes – and artefacts with no patina – possibly synchronous of the colluvia. Technical and typological features observed in these two sets suggest that the first one may date from the last glacial period (minimum age) and the second one from the Holocene.

(2011) – Stra tig ra phy, palynology and or ganic geo chem is try of the De vo nian-Mis sis sip pian metasedimentary Albergaria-a-Velha Unit (Porto–Tomar shear zone, W Por tu gal). Geol. Quart., 55 (2): 139–164. Warszawa. The Albergaria-a-Velha Unit is one of sev eral tectonostratigraphic out-of-se quence units of the meta mor phic belt as so ci ated with the Porto–Tomar shear zone (Ossa–Morena Zone, W Por tu gal). It is com posed of con sid er ably de formed – very low grade – meta sedi ments, namely shales, siltstones and rare fine sand stones. In this work we pres ent new sedimentological and biostratigraphical data that sug gest the Albergaria-a-Velha Unit was de pos ited from the (?)early Frasnian to the Serpukhovian in a dis tal ma rine en vi ron ment, where turbiditic and basinal sed i men ta tion pre vailed. Palynofacies anal y sis and lithological data point to a grad ual in crease of ter res trial in put, sug gest ing a prograding sys tem. De tri tal frame work data is in dic a tive of a sta ble cratonic sed i ment source area com posed of low grade meta mor phic rocks. The tim ing of the on set of the Porto–Tomar shear zone ac tiv ity and con se quently its in flu ence on the sed i men ta tion of this unit is dis cussed. Or ganic pe trol ogy and geo chem is try data in di cate that the Albergaria-a-Velha Unit is within the dry gas win dow in terms of hy dro car bon gen er a tion ranges.

One of the most common characteristics of the Portuguese littoral is the existence of a planed surface (the so-called " littoral platform "), situated at different altitudes and bordered from the inland by a straight relief, strongly contrasting with that planed surface. This one is generally covered with several outcrops of the so-called Plio-Pleistocene deposits. Till the eighties this platform has been interpretated as stable staircase of old marine levels, registering in a passive way the eustatic variations. The rigid step bordering it easterly should be a fossil cliff. However, our study has proved that many of these deposits have a continental origin. These continental deposits have fluvial or alluvial fan facies and they are lying above 40 meters. Marine deposition seems to be quite rare and it only occurs on a small western area, beneath the altitude of 40 meters, and developing into three different marine levels. There is a rigid step between the two kinds of deposits. We think that the clear geometric separation between these deposits together with this rigid step, indicates the results from tectonic activity. It seems that the sea must have touched only the western part of this surface, when neotectonic movements lowered it down. There are more evidences for neotectonic movements: a) there are faults (mainly inverse faults) affecting the higher deposits of this littoral platform; b) the same marine level seems to appear at different altitudes, developing an irregular pattern with a general trend dipping from the North to the South.

Abstract: Atlantico Beach is located between Valadares and France!os, 6 km to the south of the Douro mouth, in the
Vila Nova de Gaia municipality (Northern Portugal). It is a coastal sector where beach sands and dunes generally lay
over precambrian rocks belonging to the Ossa-Morena Zone. The construction of a block protection for the submarine
exhaust of the Wastewater Treatment Plant situated 3,7km to the North, triggered significant erosion and the partial
destruction of a restaurant at Francelos. The sequence of storms that affected the Portuguese coast in the Winter of 2014
caused generalized beach erosion along Portuguese westem coast. On December 30th, 2014, an almost continuous and
insightful deposit sequence was visible at Atlanfico beach. On January 3, 2015 it was possible to perform a drone flight.
The fine quality of the outcrop and the photographs, their geo-referencing and precise altimetry (GPS with differiential
correction) allowed detailed mapping of marine and solifluxive deposits and it is a good contribution to the study of
climate and related sea level changes in the last 125,000 years. All this reinforces the importance of using drone
technology in coastal environments.

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

The present study identifies the staircase development of shore platforms at Montedor - Viana do
Castelo, using the data obtained by the method of Communicating Vessels and GPS. It was found
that both devices provide identical results and operation time. There were identified four different
shore platforms above the actual (0,4/1,8 meters), at 2,8/3,4 - 4,5/5,5 - 6,6/7,4 and 8,5/9,2 meters.
A tectono-eustatic origin of this staircase development is proposed, by excluding the influence of
structural inheritance, such as sub-horizontal fracturing, in its genesis.

Northern Portugal is located in a tectonically complex area affected by major strike-slip zones,
namely the north-northwest-trending Porto–Coimbra–Tomar fault zone and the north-northeasttrending
Verin–Régua–Penacova sinistral strike-slip fault. Within this region, the sector between
Albergaria-a-Velha and Águeda is crucial since it is highly affected by large-scale strike-slip faults
and extensional deformation events. Late Cenozoic tectonics in northern Iberia resulted from the
collision of the Africa and Eurasia plates, especially in the eastern segment of the Azores–Gibraltar
plate boundary. The continued plate indentation originated the movement of major strike-slip faults
in the Iberian Massif. The movement on these faults, accompanying the regional stress-field during
the early Miocene, initiated the formation of incipient Cenozoic pull-apart basins.
The Albergaria-a-Velha–Águeda fault segment has been studied in an attempt to clarify the dynamic
relationship between this active fault zone and the evolving landscape. Three geomorphological
sectors were identified in the Albergaria-a-Velha region: (i) a littoral platform consisting of a polygenic
erosion surface overlain by late Cenozoic alluvial–fluvial sequences; (ii) a tectonically controlled
basin (Valongo do Vouga basin) located between hillslopes of two river valleys and normal
faults with N–S orientation, where late Cenozoic subsidence is suggested by an influx of alluvial
sandy conglomerates; and (iii) a domain of inner elevations of wide metapelitic landforms.
Reactivation of the prevailing north-northwest-striking Upper Proterozoic/Palaeozoic basement is
a regionally important control on the orientation and kinematics of late Cenozoic faults. Thus,
the opening and development of these basins was influenced by the intersection of the northnorthwest-
trending dextral faults with north-northeast-trending sinistral faults associated with
north–south shortening and east–west extension.
Keywords Basement, Iberian Massif, Porto–Coimbra–Tomar fault zone, relief, strike-slip
basins.

Resumo: O sector costeiro que vai desde o Cabedelo até á praia de Lavadores, constitui um dos elementos naturais mais interessantes do litoral de Vila Nova de Gaia. A sua riqueza revela-se na diversidade de aspectos geológicos e geomorfológicos, não só sob o ponto de vista didáctico mas também, científico. As nossas propostas relativamente a esta área alicerçam-se em três pontos: 1. realização de estudos de base de índole pluridisciplinar; 2. criação de um circuito de interpretação; 3. carta de recomendações ao poder autárquico. O risco de se perderem alguns testemunhos geológicos/geomorfológicos de inegável interesse científico justificam a urgência na preservação e valorização deste local e a necessidade de alertar as autoridades responsáveis pelo território.

Lavadores' beach stands on the South of the Douro's river mouth about 2 km from Porto. It's the only sector of litoral "high" coast at the South of Douro's. This beach stays very close to the passage through the coastline of the Porto-Tomar fault, which corresponds to the contact between the Central-Iberian and Ossa-Morena zones. Post-tectonics granite's are outcropping in this beach. The fracture net seems to control the development of the coastline, imposing a rigid orientation to the cliffs as well on certain rectlineous corridors inside between the granites' walls, which are usually abrupt. The same fracture net controls the existence of a typical block disjunction and other geomorphologic aspects of detail. We pretend to present geological and geomorphological sketches of the exposed rocks at the Lavadores beach and discuss the relationship between the geological structure (fracture net, neotectonics) and the forms due to the marine erosion.

Neste artigo analisam-se alguns perfis longitudinais de afluentes do rio Douro. Estes afluentes correm numa paisagem marcada por variações constantes de litologia, sistema de falhas (ex: falha da Vilariça) e descida do nível de base. Os tributários do rio Douro exibem um troço com forma côncava a montante e um troço rejuvenescido a jusante, separados por uma rotura de declive (knickpoint/knickzone). O troço côncavo a montante corresponde a um perfil relíquia regularizado, de idade provável Placenciano – Gelasiano, enquanto o troço rejuvenescido resulta do prosseguimento de vagas de incisão, relacionadas com o escavamento fluvial durante o Plistocénico. Usou-se a projecção do perfil relíquia para estimar a máxima incisão na desembocadura e o equivalente uplift crustal. Os diferentes valores da incisão fluvial que variam de cerca de 400 m no rio Coa a mais de 600 m no rio Paiva refletem o uplift diferencial da superfície da Meseta e dos Planaltos Centrais. As taxas de incisão, calculadas pressupondo o início do encaixe da drenagem entre 2,5 e 1,8 e Ma são consistentes com o uplift regional calculado em trabalhos anteriores nesta região.

Neste trabalho apresenta-se uma caracterização dos terraços do rio Mondego, baseada em critérios geomorfológicos e sedimentológicos, em particular os que se localizam entre Maiorca e Vila Verde.
Na área vestibular do rio Mondego, Ramos (2008); Ramos et al. (2009) distinguiram seis episódios de escavação-agradação, cujos níveis foram designados por M1 a M6 (do mais alto para o mais baixo), situados abaixo da superfície culminante do enchimento sedimentar e acima da planície aluvial actual (3m de altitude).
A maioria dos níveis inferiores correspondem a terraços sedimentares, com associações de fácies deposicionais distintas nos vários níveis.
As associações de fácies que caracterizam M1, M2 e M3 (depósitos dos níveis mais antigos) são de natureza areno-cascalhenta e lutítica associadas a processos fluviais, bem como arenosas finas de génese eólica. Contudo, as fácies são difíceis de analisar espacialmente, nomeadamente as cascalhentas, por os depósitos estarem dispersos em retalhos e porque a unidade subjacente (do Cretácico) também é conglomerática. São exemplos destes depósitos os que se observam na Serra de S. Bento (126m de altitude; 123m acima da planície aluvial); Serra de Castros (118m) e Serra de Moinhos (100m).
O registo sedimentar de M4, M5 e M6 (terraços mais recentes) é o que está melhor preservado e as associações de fácies distinguem-se claramente das dos terraços mais antigos. A sua observação pode fazer-se entre Lares e Vila Verde, a altitudes que rondam os 10-20m. Interpretam-se associações de fácies fluviais, estuarinas e de praia.

Resumo: Recentemente foram abertas duas trincheiras no segmento central (Vilariça) da falha de Manteigas-Vilariça-Bragança, uma com o objectivo de efectuar um estudo paleossismológico detalhado na Qta. do Vale Meão (Bacia da Vilariça) e outra com um objectivo essencialmente exploratório na Qta. da Canameira (Bacia da Longroiva). Os resultados preliminares evidenciaram a presença de sedimentos fluviais recentes deformados e falhados em Vale Meão, enquanto no sector da Qta. da Canameira se observou uma aparente deformação superficial, requerendo estudos complementares para a sua confirmação e caracterização. Os dados obtidos em Vale Meão confirmam a actividade paleossísmica caracterizada numa trincheira previamente aberta na vizinhança, embora a deformação agora detectada seja muito inferior à esperada. A deformação reduzida observada poderá dever-se a uma cinemática predominante em desligamento (esquerdo) e à ocorrência de deformação distribuída nos sedimentos finos afectados, que apresentam mais de 8 m de espessura.
Palabras clave: paleossismologia, falhas activas, geomorfologia tectónica, falha da Vilariça

Abstract: Two new trenches were recently opened in the central segment (Vilariça) of the Manteigas-Vilariça-Bragança fault to undertake a detailed paleoseismological study at Quinta do Vale Meão (Vilariça Basin) and an exploratory study at Quinta da Canameira (Longroiva Basin), respectively. Preliminary results show that recent sediments are deformed and faulted in Vale Meão, while at Canameira they showed apparent deformation requiring further exploration to confirm the observations. The new data obtained in Vale Meão confirmed the paleoseismic activity previously inferred from a nearby trench, though the deformation observed in this study was much lower than expected. The smaller amount of deformation that was detected at the Vale Meão trench may be due to the predominant strike-slip (left-lateral) kinematics and to strain distribution in the affected fine grained sediments, which are locally more than 8 m thick.

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 characterization and interpretation of the Pliocene and Pleistocene geomorphological and sedimentary records of Peniche - Atouguia da Baleia littoral are here presented. Several wave-cut platforms were characterized and mapped, respectively, at: 33-36 m, a vast culminant surface only locally preserved, associated with yellowish fine to very coarse pebbly sands, and also by very coarse whitish sands; 24-27 m, a very wide wave-cut platform covered by whitish bioclastic pebbly sands sometimes cemented; 20-21 m, only locally represented, with some very coarse whitish very coarse sandstones; 15-17
m, covered by fine to very coarse pebbly yellowish sands, with a fossiliferous travertine breccia at top; 10-12 m, with yellowish very coarse sandstones, with a travertine breccia at top; and 6-8 m, with a marine conglomerate and an upper coarse sandstone.
The culminant marine platform and associated marine deposits are correlated with the important marine incursion dated as 3.7 Ma and the five marine terraces that are located above the modern wave-cut platform ate correlated to the periods of highest sea-level during the Pleistocene MIS’s. In Furninha cave, the succession of aeolian fine sands intercalated with levels rich in fossils containing industries of Middle to Upper Palaeolithic should bracket the interval 80-12ka (MIS4, MIS3 and MIS2), coeval with the lowering of sea-level and cold climate conditions. The consolidated late Pleistocene aeolian pink fine sands are covered by whitish loose fine sands (MIS1).