Depósitos messinianos do sul de Portugal, mamíferos (incluindo Rodentia e Logomorpha) e idades K-Ar

In the southern part of Tagus basin, North of paleozoic rocks of Valverde-Senhor das Chagas (near Alcácer do Sal) horst, a marine transgression has been recognized, Upper Serravallian, and maybe Lower Tortonian in age. There are no earlier marine deposits, and no younger ones are known either. Paleozoic behaved as a barrier separating two basins, distinct at least since Middle Miocene until Upper Pleistocene. Until now, both were regarded as a single entity, the so-called «Sado basin» Southwards (Alvalade basin) there has been a single transgression. It was assummed that it was the same one as the former. Indeed it is not definitely so. Later transgression accounts for Esbarrondadoiro Formation, whose deposits have been ascribed to Tortonian or even to Middle Miocene. However they are Upper Messinian to Lower Zanclean. Esbarrondadoiro Formation is younger than Lower Member of Cacela Formation in Algarve and, with even stronger reason, than the upper-most well dated marine levels in Tagus basin. Age of Miocene units dealt with here has been based on small mammals found in marine sands.

Petits mammifères du burdigalien infèrieur (Universidade Católica, Avenida do Uruguay)

Improved bromoform concentration as developped at CEPUNL allowed better recovery of small mammals'teeth. At Universidade Católica and Avenida do Uruguay 19 taxa (and a further one with doubt) were recognized. Some are new for the level and for Tagus basin: Lagopsis cadeoti and Melissiodon dominans (1st reference for the genus); Glirudinus modestus (formerly under another name); Armantomys (1st reference for this level); Peridyromys murinus (referred before under another name); Microdyromys legidensis (1st ref. of gen. and sp. for this level); and Heteroxerus rubricati, formerly reported to other species of the same genus. Both localities share the same position viz marine levels under and above. This allows us to correlate them with NS or N6 Blow's zones. Both are distinctly younger-than glauconite in underlying beds about 21 MY old (K-Ar). Small mammals point out to MN3a Neogene subunit. Fauna is much alike Lower Burdigalian ones in Spain, France, Germany and Austria. Terrestrial, maybe steppe forms predominate. Land environment was open, with scant plant cover but not devoid of trees. Peridyromys murinus numerical importance and other data suggest a not so warm climate in correspondance to a minimum temperature event. This is corroborated by associated marine fish fauna entirely without warm water stenotherm species, and by paleobotanical/palynological data. Results are in close agreement with Central Northern Spain. The localities studied here are even more interesting as direct correlations between marine and continental stratigraphical scales are possible.

Évolution de la végétation et du climat pendant le miocène au Portugal

These work presents the quantitative and qualitative inventory and the stratigraphic distribution of fossil plants (spores, pollens, sterns, leaves and seeds) recognized the Miocene of the portuguese part of Tagus basin. For each lithostratigraphic unit, associations with ecological (paleoclimatic) meaning are defined. It was also possible to follow the evolution of the vegetation and the climate during the considered cronostratigraphic interval which includes most of the Miocene (Aquitanian to lower-middle Tortonian).

Evolução paleogeográfica e paleobiogeográfica do Caloviano-Kimeridgiano do Algarve

The littoral and the «barrocal» of the Algarve correspond in part to a meso-cenozoic sedimentary basin with a deeping south monocline structure, cut by North-South faults and by two East-West longitudinal flexures. The lithostratigraphic and chronostratigraphic study of the Jurassic formations, undertaken during the last years, allow a better knowledge of the paleogeographic and paleobiogeographic evolution of these formations and particularly of the Callovian-Kimmeridgian. Lower Callovian facies, being similar from Sagres in the West to beyond Tavira, show the uniformity of the sedimentary conditions. Since Middle Callovian, the beginning of the regressive cycle is responsible for a major unconformity between Dogger and Malm. During the Lower Oxfordian a new sedimentary cycle begins with a transgression afecting the region south of the Albufeira-São Brás de Alportel-Tavira line thus originating a gulf centered in the Loulé area which rapidly diminishes since the Lower Kimmeridgian. The faunistic affinities are always tipically tethyan although some classic boreal fauna exist, in contrast with the Northern Tagus basin (where affinities are sub-boreal during the Callovian).

Nouvelles espèces d’ostracodes du miocène du basin du Tage (Portugal)

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

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.

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.

Interpretação tectónica de um conjunto de lineamentos WNW-ESE observados em imagens landsat da margem oeste ibérica

The existence of satellite images ofthe West Iberian Margin allowed comparative study of images as a tool applied to structural geology. Interpretation of LANDSAT images of the Lusitanian Basin domain showed the existence of a not previously described WNW-ESE trending set oflineaments. These lineaments are persistent and only observable on small scale images (e.g. approx. 11200000 and 11500 000) with various radiometric characteristics. They are approximately 20 km long, trend l200±15° and cross cut any other families oflineaments. The fact that these lineaments are perpendicular to the Quaternary thrusts of the Lower Tagus Valley and also because they show no off-set across them, suggests that they resulted from intersection oflarge tensile fractures on the earth's surface. It is proposed in this work that these lineaments formed on a crustal flexure of tens ofkm long, associated with the Quaternary WNW-ESE oriented maximum compressive stress on the West Iberian Margin. The maximum compressive stress rotated anticlockwise from a NW -SE orientation to approximately WNW-ESE, from Late Miocene to Quaternary times (RIBEIRO et aI., 1996). Field inspection of the lineaments revealed zones of norm~1.J. faulting and cataclasis, which are coincident with the lineaments and affect sediments of upper Miocene up to Quaternary age. These deformation structures show localized extension perpendicular to the lineaments, i.e. perpendicular to the maximum compressive direction, after recent stress data along the West Portuguese Margin (CABRAL & RIBEIRO, 1989; RIBEIRO et at., 1996). Also, on a first approach, the geographical distribution of these lineaments correlates well with earthquake epicenters and areas of largest Quaternary Vertical Movements within the inverted Lusitanian Basin (CABRAL, 1995).

Water option contracts for reducing water supply risks: an application to the Tagus-Segura Transfer

El agua es un recurso cada vez más escaso y valioso. Por ello, los recursos hídricos disponibles deben asignarse de una forma eficiente entre los diferentes usos. El cambio climático aumentará la frecuencia y severidad de los eventos extremos, y podría incrementar la demanda de agua de los cultivos. El empleo de mecanismos flexibles de asignación de agua puede ser imprescindible para hacer frente a este aumento en la variabilidad del balance hídrico y para asegurar que los riesgos de suministro, y no solo los recursos, son compartidos de manera eficiente entre los usuarios. Los mercados de agua permiten la reasignación de los recursos hídricos, favoreciendo su transferencia desde los usos de menor a los de mayor valor. Diferentes tipos de mercados de agua se han establecido en diferentes partes del mundo, ayudando a los participantes a afrontar los problemas de escasez de agua en esas zonas. En España, los intercambios de agua están permitidos desde 1999, aunque la participación de los usuarios en el mercado ha sido limitada. Hay varios aspectos de los mercados de agua en España que deben mejorarse. Esta tesis, además de proponer una serie de cambios en el marco regulatorio, propone la introducción de contratos de opción de agua como una posible mejora. La principal ventaja de este tipo de contratos es la estabilidad legal e institucional que éstos proporcionan tanto a compradores como vendedores. Para apoyar esta propuesta, se han llevado a cabo diferentes análisis que muestran el potencial de los contratos de opción como herramienta de reducción del riesgo asociado a una oferta de agua inestable. La Cuenca del Segura (Sureste de España), la Cuenca del Tajo y el Acueducto Tajo- Segura han sido seleccionados como casos de estudio. Tres análisis distintos aplicados a dicha región se presentan en esta tesis: a) una evaluación de los contratos de opción como mecanismo para reducir los riesgos de disponibilidad de agua sufridos por los regantes en la Cuenca del Segura; b) un marco teórico para analizar las preferencias de los regantes por diferentes mecanismos de gestión del riesgo de disponibilidad de agua, su disposición a pagar por ellos y los precios aproximados de estos instrumentos (seguro de sequía y contratos de opción de agua); y c) una evaluación del papel de los contratos de opción en las decisiones de aprovisionamiento de agua de una comunidad de regantes ante una oferta de agua incierta. Los resultados muestran el potencial de reducción del riesgo de los contratos de opción para regantes en España, pero pueden ser extrapolados a otros sectores o regiones. Las principales conclusiones de esta tesis son: a) la agricultura será uno de los sectores más afectados por el cambio climático. Si los precios del agua aumentan, la rentabilidad de los cultivos puede caer hasta niveles negativos, lo que podría dar lugar al abandono de cultivos de regadío en algunas zonas de España. Las políticas de cambio climático y de agua deben estar estrechamente coordinadas para asegurar un uso de agua eficiente y la rentabilidad de la agricultura; b) aunque los mercados de agua han ayudado a algunos usuarios a afrontar problemas de disponibilidad del recurso en momentos de escasez, hay varios aspectos que deben mejorarse; c) es necesario desarrollar mercados de agua más flexibles y estables para garantizar una asignación eficiente de los recursos entre los usuarios de agua; d) los resultados muestran los beneficios derivados del establecimiento de un contrato de opción entre usuarios de agua del Tajo y del Segura para reducir el riesgo de disponibilidad de agua en la cuenca receptora; e) la disposición a pagar de los regantes por un contrato de opción de agua o un seguro de sequía hidrológica, que representa el valor que tienen estos mecanismos para aquellos usuarios de agua que se enfrentan a riesgos relacionados con la disponibilidad del recurso, es consistente con los resultados obtenidos en estudios previos y superior al precio de mercado de estos instrumentos, lo que favorece la viabilidad de estos mecanismos de gestión del riesgo ; y f) los contratos de opción podrían ayudar a optimizar las decisiones de aprovisionamiento de agua bajo incertidumbre, proporcionando más estabilidad y flexibilidad que los mercados temporales de agua. ABSTRACT Water is becoming increasingly scarce and valuable. Thus, existing water resources need to be efficiently allocated among users. Climate change is expected to increase the frequency and severity of extreme events, and it may also increase irrigated crops' water demand. The implementation of flexible allocation mechanisms could be essential to cope with this increased variability of the water balance and ensure that supply risks, and not only water resources, are also efficiently shared and managed. Water markets allow for the reallocation of water resources from low to high value uses. Different water trading mechanisms have been created in different parts of the world and have helped users to alleviate water scarcity problems in those areas. In Spain, water trading is allowed since 1999, although market activity has been limited. There are several issues in the Spanish water market that should be improved. This thesis, besides proposing several changes in the legislative framework, proposes the introduction of water option contracts as a potential improvement. The main advantage for both buyer and seller derived from an option contract is the institutional and legal stability it provides. To support this proposal, different analyses have been carried out that show the potential of option contracts as a risk reduction tool to manage water supply instability. The Segura Basin (Southeast Spain), the Tagus Basin and the Tagus-Segura inter-basin Transfer have been selected as the case study. Three different analyses applied to this region are presented in this thesis: a) an evaluation of option contracts as a mechanisms to reduce water supply availability risks in the Segura Basin; b) a theoretical framework for analyzing farmer’s preferences for different water supply risk management tools and farmers’ willingness to pay for them, together with the assessment of the prices of these mechanisms (drought insurance and water option contracts); and c) an evaluation of the role of option contracts in water procurement decisions under uncertainty. Results show the risk-reduction potential of option contracts for the agricultural sector in Spain, but these results can be extrapolated to other sectors or regions. The main conclusions of the thesis are: a) agriculture would be one of the most affected sectors by climate change. With higher water tariffs, crop’s profitability can drop to negative levels, which may result in the abandoning of the crop in many areas. Climate change and water policies must be closely coordinated to ensure efficient water use and crops’ profitability; b) although Spanish water markets have alleviated water availability problems for some users during water scarcity periods, there are several issues that should be improved; c) more flexible and stable water market mechanisms are needed to allocate water resources and water supply risks among competing users; d) results show the benefits derived from the establishment of an inter-basin option contract between water users in the Tagus and the Segura basins for reducing water supply availability risks in the recipient area; e) irrigators’ willingness to pay for option contracts or drought insurance, that represent the value that this kind of trading mechanisms has for water users facing water supply reliability problems, are consistent with results obtained in previous works and higher than the prices of this risk management tools, which shows the feasibility of these mechanisms; and f) option contracts would help to optimize water procurement decisions under uncertainty, providing more flexibility and stability than the spot market.

Hydrologic data, Mekong River Basin; a report, 1960 [-19 ]

English and French.

Strength of the Iberian intraplate lithosphere: Cenozoic deformations and seismicity

Previous studies about the strength of the lithosphere in the Iberia centre fail to resolve the depth of earthquakes because of the rheological uncertainties. Therefore, new contributions are considered (the crustal structure from a density model) and several parameters (tectonic regime, mantle rheology, strain rate) are checked in this paper to properly examine the role of lithospheric strength in the intraplate seismicity and the Cenozoic evolution. The strength distribution with depth, the integrated strength, the effective elastic thickness and the seismogenic thickness have been calculated by a finite element modelling of the lithosphere across the Central System mountain range and the bordering Duero and Madrid sedimentary basins. Only a dry mantle under strike-slip/extension and a strain rate of 10-15 s-1, or under extension and 10-16 s-1, causes a strong lithosphere. The integrated strength and the elastic thickness are lower in the mountain chain than in the basins. These anisotropies have been maintained since the Cenozoic and determine the mountain uplift and the biharmonic folding of the Iberian lithosphere during the Alpine deformations. The seismogenic thickness bounds the seismic activity in the upper–middle crust, and the decreasing crustal strength from the Duero Basin towards the Madrid Basin is related to a parallel increase in Plio–Quaternary deformations and seismicity. However, elasto–plastic modelling shows that current African–Eurasian convergence is resolved elastically or ductilely, which accounts for the low seismicity recorded in this region.

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

In the Vi la de Rei arca (Central Portugal) the continental deposits ofthe Lower Tagus Tertiary 8asin lay upon the pediment of me Portuguese Central Chain. Three ronglomerate units are recorded from me base upwards. separated by regional or basinal unconfonnities: Conglomerados de Rio de Moinhos (RM); Conglomerados de Serra de Almeirim (SA) and Conglomerados de Vila de Rei (VR). The first two units (KM and SAl have been si les of gold exploitation in huge optn pit mines probably dunng Roman colonisation times. The contact ofthis units, on thc Paleozoie basement or on the Paleogene unil Grés de Monsanto, is unconfonn, defining in both limits a large nondepositional andlor erosional hiatus. Those conglomerates seal the scdimcntation ofthe Lower Tagus Tertiary Basin along irs northem border. Taking lnto account lhe significance /lssigned to their basinal unconfonnity limits, lhe uplift ofthe Portuguese Centra! Chain. and thc facl ofthis continental units yielded no fossils with chranostratigraphic significanee, they have been eonsidered ranging fram Uppcr Miocene to lhe beginning ofthe Qualemary. Finally, a lithostratigraphic equivalence with lhe Neogenic units ofthc Bierzo and Duema basins (NW ofthe Iberian Peninsula), where exploitalions from Roman limes are also evident, is presented.

Confirmação do modelo da estrutura 3D do vale inferior do Tejo a partir de dados de ruído sísmico ambiente

Ao longo de sua história a região do Vale Inferior do Tejo VIT foi abalada por vários sismos consideravelmente destrutivas, tendo alguns deles produzido significativas deformações nas estruturas marítimas localizadas no litoral a sudoeste do território Português; outros, moderados, foram produzidos por fontes locais, como os de 1344, 1531 e 1909. Nos últimos anos, devido à melhoria dos modelos de estrutura 3D e o desenvolvimento dos métodos numéricos, foram elaborados vários estudos de síntese de movimento forte do solo para a região do Baixo Tejo utilizando o método de diferenças finitas. Para confirmar o modelo de velocidades desta bacia usámos medidas de ruído sísmico, aplicámos um método baseado na razão espectral H/V, e, a partir destas curvas, por inversão, obtivemos um modelo de velocidades para a região estudada. Os resultados revelam uma boa concordância entre o modelo obtido e os dados geofísicos e geológicos recolhidos na mesma área._ ABSTRACT: Along his history the Lower Tagus Valley (LTV) area was shaken by several earthquakes. The largest reported had their origin in the southwestern part of Iberia. Other moderate earthquakes were produced by local sources such as the 1344, 1531 and the 1909. ln the last years, due to 3D structural model improvement and development in numerical methods, several studies have successful obtained strong-ground motion synthesis for the LVT region using finite difference method. To confirm the velocity model of the LTV sedimentary basin obtained by geophysical and geological data, we use broad-band microtremor measurements and application of the horizontal to vertical (H/V) spectral ratio method. We have obtained a velocity model for the studied region by inversion of the H/V curve. The results have good agreement geological and geophysical data.

Contributions à la Paléontologie du Miocène moyen continental du Bassin du Tage. I - Quelques mollusques - Pero Filho, Póvoa de Santarém, Sítio do Mirante

Some land and freshwater mollusks (Gastropoda, Pelecypoda) from three middle Miocene localities: Pêro Filho, Póvoa de Santarém, Sítio do Mirante, all in Ribatejo province, Portugal, are summarily studied. On a systematical viewpoint it has been shown (see also Tableau): - the presence of the genus Janulus, whose species only survive now at Madeira and Canary's islands; - the presence of "Helix" cotteri that may indeed belong in the genus Megalotachea, common in western Europe since "Helvetian" to Messinian times; - Limax, Testacella, Acroloxus and Pseudamnicola are quoted for the first time in portuguese tertiary formations; Ferrisia has been identified for the first time in Iberian Peninsule; - the presence of other forms previously quoted by ANTUNES & ZBYSZEWSKI (1973), is confirmed: Bithynia, Theodoxus, Pisidium. Such faunules are compatible with a middle Miocene age. On a paleobiogeographical viewpoint, some forms suggest mediterranean affinities. Fossil associations do correspond ecologically to either palustrine or stagnant, calm and shallow water conditions (Sítio do Mirante, and essentially also Póvoa de Santarém), or to fluviatile conditions (Pêro Filho).

Contributions à la Paléontologie du Miocène moyen continental du Bassin du Tage. II - Observations sur les dents pharyngiennes de poissons cyprinidés - Póvoa de Santarém.

The study of Cyprinid fish pharyngeal teeth, collected by M. Telles Antunes in continental "Helvetian" sediments from Póvoa de Santarém, makes possible to demonstrate the occurrence of two distinct species. One remains undetermined. The other belongs to the recent genus Leuciscus CUV. Several dental types of this genus are described and figured as Leuciscus antunesi nov. sp. Palaeoclimatical and palaeoecological interpretations are proposed.