Dinossauros e Portugal: dois casos menos conhecidos

After some remarks on the protection of sites recognized as most interesting, two less known items about dinosaurs and Portugal are dealt with. The first of theme concerns the first published account on dinosaur tracks. Jacinto Pedro Gomes, then (1884) preparing a report on the Cabo Mondego coal mines, was told of the occurrence of large footprint casts that subsequently were sent to the Museum of the Escola Politécnica in Lisbon. Gomes has shown drawings of them to B. Geinitz (Dresden), who ascribed the casts to dinosaurs. Karl Zittel (München), corroborated this viewpoint, and Louis Dollo (Brussels) reported them to Ornithopods. A posthumous note by GOMES (1915-1916) is the first scientific paper on dinosaur tracks in Portugal. However, it is not the first published report. João Bonança, a reporter, presented in his large book "HISTORIA / DA / LUZITANIA E DA IBERIA ..." (1891), a new (both irrealistic and useless) stratigraphic classification. He also replaced Zoological and Botanic Nomenclature by another one devised by him. Having seen the footprint casts at the Museum of the Escola Politécnica, he referred bird or dinosaur footprints in Cabo Mondego's Upper Jurassic, this being the first published report on such fossils as far as Portugal is concerned. The second theme is about Late Cretaceous dinosaurs from Viso, Aveiro and Taveiro. Faunas are marked by generalized nannism, and seem impoverished by previous extinctions of larger forms; their probable insular character has been acknowledged. Extinctions may well be explained by non-catastrophic causes. The general fall of temperatures may have been far more important.

Restos de Anchitherium de Lisboa, Portugal

The Anchitherium remains from several Portuguese localities placed on IVb and Vb (Lisbon area) levels are studied. They are compared with the French and Spanish remains, and particularly with those from the Madrid basin. They are identified as Anchitherium cf. A. ezquerrae from the Vb level remains, because the remains are very scarce.

Sélaciens du Miocène terminal du bassin d'Alvalade (Portugal). Essai de synthèse

A rich uppermost Miocene selachian fauna from the Alvalade Basin (represented by more than 10.000 teeth) is accounted for. It is the most modern miocene fauna of neritic habit under warm-temperate to subtropical conditions, known in the european Miocene.

Veiga Ferreira e a Paleontologia em Portugal

This communication deals with the less known research activities on Palconlology by Octávio da Veiga Ferreira, since just after he became a member of the staff of the Serviços Geológicos de Portugal. These activities lasted for about 25 years (1951-1975, eventually up to 1987). Besides much field and laboralory work, Veiga Ferreira produced (alone or in collaboration} 38 papers. These concern vertebrates, echinoids, pectens and other molluscs, and malacostraca, as well as some papers of a more general or divulgation character. Studied fossils range from Jurassic to Quaternary, and from continental Portugal to Santa Maria Island (Azores), the Madeira Archipel and Angola. Veiga Ferreira is author of much valid work. He generously helped others as well. A bibliography for his paleontological papers is provided.

Invertebrados y micropaleontología en la evolución de la Cuenca del Guadalquivir (España) y la Plataforma del Algarve (Portugal)

Based upon the depositional sequences in the Guadalquivir basin and the bio-events defined (foraminifera and nanoplancton) we present the synthesis of the paleontological results in correlation with the Neogene of Algarve (Portugal). We present the most representative outcrops for micropaleonlologic results, as well as paleoenvironmental correlations between Algarve and the Guadalquivir basin.

Assinatura tectono-sedimentar do auge da compressão bética em Portugal: a descontinuidade sedimentar Valesiano terminal-Turoliano

An Upper Miocene important sedimentary break can be accurately recognised in the Portuguese basins and is reflected by a drastic palaeogeographic change in relation to a large-scale tectonic event of probable uppermost Vallesian-Turolian (9,5 Ma; middle Tortonian) age. The characterisation of the sedimentary record of this tectonic event, as well as its relations with interpreted active faults is made for different situations: Douro (NW border), Mondego, Lower-Tagus and Sado Tertiary basins. The sedimentary record, considered upper Tortonian-Messinian ? (uppermost Vallesian-Turolian ?) is interpreted mainly as endorheic alluvial fans (internal drainage), developed along active NNE-SSW indent-linked strike-slip faults and NE-SW reverse faults. At NE Portugal, proximal fluvial systems of an endorheic hydrographic network drained eastwards to the Spanish Duero interior Basin. The main evidences of the betic compression clímax in Portugal mainland are presented; the interpreted active tectonic structures are in accordance with an intense NNW-SSE crustal shortening, but some regional differences are also documented.

Mineralogia da fracção argilosa da Formação de Vale Álvaro (Bragança, NE Portugal)

The studied materials were sampled from several conglomerate and carbonate sandstone units, overlapped for 23 meters. This formation represents a debris flow dominated alluvial fan alternating with quiet sedimentary conditions. These deposits of probably Paleogene age were placed upon mafic and ultramafic rocks that are the exclusive source of sediments. Optical and SEM identification, microanalysis and XRD studies (with decomposition procedures) of clay fractions obtained after high-speed centrifugation were performed in order to characterise the clay minerals content. The results of the analytical program allowed the establishment of the following remarks: a) Fe-rich montmorillonite dominance over paligorskite, chlorite, chlorite-smectite mixed-layers, serpentine and talc; b) smectites in the 12.4 - 15 A range, expanding to about 17 A after EG treatment; c) serpentine and talc as secondary minerals in the interior of altered clasts; d) chlorite and clorite smectite mixed-layer compositions in the borders of the clasts and in the cement. The composition of sediments results from coarse clasts eroded from mafic and ultramafic rocks and clayey material. Clasts show evidences of post-depositional weathering (coatings of chlorite and smectite). Clayey material has the contributions of i) inherired chlorite, smectite and chlorite-smectite mixed-layers; ii ) authigenic crystallisation of Fe-montmorillonite (due to availability of Fe in the crystallising solutions following previous weathering events); iii) authigenic paligorskite associated to a carbonate cement.

Evolução cenozóica da área de Longroiva-Vilariça (NE Portugal)

In the Longroiva-Vilariça area, the identification of Cenozoic lithostratigraphic units, the sedimentology and the characterization of its geometric relations with tectonic structures allowed the interpretation of the palaeogeographic main stages: 1) the greenwhitish Vilariça Arkoses (Middle Eocene to Oligocene ?) represent proximal sediments of a very low gradient drainage towards the eastern Spanish Tertiary Duero Basin; 2)Quintãs Formation (late Miocene ?) are brown-reddish coloured piedmont alluvial deposits, correlative of important vertical displacement (western tectonic block relative uplift) along the NNE-SSW indent-linked strike-slip Bragança-Vilariça-Longroiva fault zone, interpreted as a reactivated deep hercynian fracture, with left-lateral movement; 3) the red Sampaio Formation (Gelasian-early Pleistocene ?)was interpreted as downhill conglomeratic deposits related with important overtrusting along this fault zone (the definition of the present-day narrow graben configuration) and correlative of the atlantic hydrographic incision stage beginning; 4) conglomeratic terraces (middle and late Pleistocene ?); 5) alluvial plains and colluvial deposits (Holocene).

A sedimentação e a gliptogénese no registo cenozóico continental do Minho (NW Portugal)

This study identifies and describes the major Cenozoíc glyptogenesis and sedimentation episodes in the Minho region (NW Portugal). The fluvial processes of exorheic network were mainly the builders of Cenozoic landscape. This paper presents a chronological sequence of the major fluvial events based on geomorphology and sedimentary characteristics obtained in former studies and new ones. The oldest Cenozoic sedimentation (Placencian) remains on local depressions and was generated by fluvial and fluvio-lacustrine processes. Quaternary glyptogenesis begins probably with a major European cooling (Gunz?). So, the Placencian infilling was eroded and a new episode of sedimentation was accumulated in the same early paleovalley. There were three more cycles of quaternary glyptogenesis and sedimentation. The last glyptogenesis episode records the last glacial period. The post-glacial alluvion contains clasts of granites, schists, feldspats, and other alterable lithologies and minerals; on clay dimensions there are abundant illite and interstratified minerals. This composition differs from the older ones, more siliciclastic and kaolinitic. Other minor erosion episodes were identified, controlled manly by eustasy; evidences of tectonic movements were observed only in rio Minho valley.

Paleoambiental reconstruction based on mineralogical data of quaternary littoral deposits occuring at Cortegaça and Maceda beaches (Ovar, Portugal)

The main goal of the present work is the use of mineralogical data corresponding to sediment fine fractions (silt and clay) of Quaternary littoral deposits for the definition of a more detailed vertical zonography and to discriminate the most significant morphoclimatic changes concerned with sediment source areas and sediment deposition areas. The analysis of the available mineralogical data reveals a vertical evolution of the mineral composition. The following aspects deserve particular reference: 1) fine fractions (<38 nm) are composed of quartz and phyllosilicates associated to feldspars, prevailing over other minerals; however in certain sections iron hydroxides and evaporitic minerals occur in significant amounts; 2) clay fractions (<2 nm) show a general prevalence of illite associated with kaolinite and oscillations, in relative terms, of kaolinite and illite contents. Qualitative and quantitative lateral and vertical variations of clay and non clay minerals allow the discrimination of sedimentary sequences and the establishment of the ritmicity and periodicity of the morphoclimatic Quaternary episodes that occurred in the Cortegaça and Maceda beaches. To each one of the sedimentary sequences corresponds, in a first stage, a littoral environment that increasingly became more continental. Climate would be mild to cold, sometimes with humidity - aridity oscillations. Warmer and moister episodes alternated with cooler and dryer ones.

Litostratigrafia do Terciario da região Miranda do Corvo-Viseu (Bacia do Mondego, Portugal)

The lithostratigraphic units (2 groups, 5 formations and 4 members) of the Tertiary of the Miranda do Corvo-Viseu region (Central Portugal) are here described. For each unit the characterization and description (boundaries, diagnostic properties and atributes) were included. The stratigraphic, lithological, sequential and tectonic data allow correlations with other units of the same Tertiary basin located more to west and support the chronostratigraphic attribution. Sedimentologic characteristics of the deposits lead to the interpretation of the influence of tectonism, climate and eustasy during the sedimentary evolution of this Basin.

Paleoalterações e cimentações nos depósitos continentais terciários de Portugal central: importância na interpretação de processos antigos

This paper describes the palaeoweathering, cementation, clay minerals association and other closely related characteristics of central Portugal allostratigraphic Tertiary units (SLD's), that can be used for palaeoclimatic interpretation and palaeoenvironmental reconstruction. Lateral and vertical changes in palaeosols are of value for improving our understanding of the autocyclic and allocyclic controls on sediment acumulation in an alluvial basin, but they can also have stratigraphic importance. In some cases it is concluded that the geomorphological setting may have been more decisive than climatic conditions to the production of the palaeoweathering. During late Palaeogene (SLD7-8), surface and near-surface silicification were developed on tectonically stable land surfaces of minimal local relief under a semi-arid climate; groundwater flow was responsible for some eodiagenesis calcareous accumulations, with the neoformation of palygorskite. Conditions during the Miocene (SLD9-11) were favourable for the smectization of the metamorphic basement and arenization of granites. Intense rubefaction associated with basement conversion into clay (illite and kaolinite), is ascribed to internal drainage during late Messinian-Zanclean (SLD12). During Piacenzian (SLD13) intense kaolinization and hydromorphism are typical, reflecting a more humid and hot temperate climate and important Atlantic fluvial drainage. Later on (Gelasian-early Pleistocene ?; SLD14). more cold and dry conditicns are interpreted, at the beginning of the fluvial incision sage. Silica cementation is identified in the upper Eocence-Oligocene ? (SLD18; the major period of silicification), middle to upper Miocene (SLD10)and upper Tortonian-Messinian (SLD11); these occurrences are compatible with either arid or semi-arid conditions and the establishment of a flat landscape upon which a silcrete was developed.

Variação dos parâmetros paleomagnéticos em perfis dos Tufos de Condeixa (Baixo Mondego, Portugal)

Paleomagnetic parameters measured in 4 outcrops of the Tufos de Condeixa are presented. The directional signatures allow the admission of the Reversed Polarity Criptchron C1n-1 in the Condeixa-a-Velha outcrop. It was possible to discuss the magnetic properties, origin of the magnetic grains and paleoclimatic variation relationships. The downward of the initial magnetization and magnetic susceplibility values in the Condeixa-a-Velha outcrop coincide with the Cln-1 (504-493 Ka) occurrence and may represent a paleoclimatic variation. The Tufos de Condeixa were formed during the Ionian-Tarentian(?).

Significado regional dos depósitos neogénicos continentais da área de Vila de Rei (Portugal Central)

In the Vila de Rei area (Central Portugal) the continental deposits of the Lower Tagus Tertiary Basin lay upon the pediment of the Portuguese Central Chain. Three conglomerate units are recorded from the base upwards, separated by regional or basinal unconformities; Conglomerados de Rio de Moinhos (RM); Conglomerados de Serra de Almeirim (SA) and Conglomerados de Vila de Rei (VR). The first two units (RM and SA) have been sites of gold exploitation in huge open pit mines probably during Roman colonisation times. The contact of this units, on the Paleozoic basement or on the Paleogene unit Grés de Monsanto, is unconform, defining in both limits a large nondepositional and/or erosional hiatus. Those conglomerates seal the sedimentation of the Lower Tagus Tertiary Basin along its northern border. Taking into account the significance assigned to their basinal unconformity limits, the uplift of the Portuguese Central Chain, and the fact of this continental units yielded no fossils with chronostratigraphic significance, they have been considered ranging from Upper Miocene to the beginning of the Quaternary. Finally, a lithostraligraphic equivalence with the Neogenic units of the Bierzo and Duerna basins (NW of the Iberian Peninsula), where exploitations from Roman times are also evident, is presented.

High resolution stratigraphy and miocene facies correlation in Lisbon and Setúbal Peninsula (Lower Tagus basin, Portugal)

Correlation between facies associations (marine, estuarine and distal fluviatile environments) and disconformities, observed between Foz da Fonte (SW of Setúbal Peninsula) and Santa Iria da Azóia (NE of Lisbon) are presented. The precise definition of the marine-continental facies relationships improved very much the chronology of the depositional sequence boundaries. Tectonic and eustatic controls are discussed on the basis of subsidence rates variation.