Microfacies studies of carbonate rocks from Jurassic outcrops in the north of Faro, Southern Portugal

The Middle and Upper Jurassique limestones investigated were sub-divided into nine microfacies (MF) types. The firsts four represent Bathonian sediments with shallow water characteristics typical for carbonate platforms. They are comparable with Wilson's facies zones 6 to 8. Reef and reef debris, near-shore clastic-dominated limestones are not present. These MF-types are reiterated several times without cyclicity. The vertical development of the differentiated facies units indicates a close interfingering. The microfacies data are typical of inter to shallow subtidal environments; both authigenous quartz and low faunal and floral diversity of several layers point to temporary restricted conditions. The occurrence of Dictyoconus cayeuxi LUCAS and Callovian ammonites from the above lying strata argue for a Bathonian age. The MF-types 5-9 (Oxfordian-Kimmeridgian) show completely different sedimentation conditions. Fully marine nearshore recifal limestones alternate with pelagic sediments formed at deeper shelf areas. The pelagic micritic limestones of Oxfordian age are characterized by allodapic intercalations whereas the Oxfordian/Kimmeridgian limestones with tuberolithic fabrics often show intensive silifications. Only initial patch reef growth-stages were reached during the development of the Oxfordian and Kimmeridgian shallow water limestones.

Stochastic modelling of the reservoir lithological and petrophysical attributes. A case study of the Middle East carbonate reservoir

Dissertação para obtenção do Grau de Mestre em Engenharia Geológica (Georrecursos)

Le gisement de Asseiceira, Portugal (Miocène supérieur) Données complémentaires sur Freiria de Rio Maior

A new upper Miocene locality at Asseiceira (Rio Maior), near the top of the "Calcários de Almoster e Santarém" unit (Almoster and Santarém limestones) is studied. Animal and plant fossils are described. Comparisons are drawn to other localities related to the same unit: Freiria and Azambujeira (middle and upper levels, both with large mammals). Small mammals from Asseiceira and Freiria point out to a rather old age amidst the upper Vallesian, MN 10 mammal-unit. This gives a fairly accurate datation for the "Calcários de Almoster e Santarém" and for the short time span of the corresponding sedimentation. Climate was warm and quite dry, with contrasting seasons and arid events. During upper Vallesian times, climate in Iberian Peninsula was varied but drier than in France, and specially so in the inner basins. However in Portugal and in Catalonia climate would he less different in comparison with that of the Rhône basin. Environmental evolution has been important: at Freiria and Azambujeira (middle level) there were mainly shallow lacustrine environments that received ressurgence waters from the nearby "Maciço calcário". Humid areas were closely surrounded by dense forests and these by broader and drier savanna or steppe areas. Still later, carbonate sedimentation ended. For some time there was still a river system with oxbows; humid areas probably were decreasing in favour of surrounding, rather dry environments. This study stressed the nced for revision of the geology of the region of Rio Maior and for a new geological mapping of that area. Environmental evolution has been important: at Freiria and Azambujeira (middle level) there were mainly shallow lacustrine environments that received ressurgence waters from the nearby "Maciço calcário".

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.

Orbital forcing of stratal patterns in an inner platform carbonate sucession: an example from an Upper Hauterivian series of the Lusitanian Basin, Portugal

With an example taken from a late-Hauterivian series of the Lusitanian Basin (Portugal), we will demonstrate the sedimentary record of orbital pattern variations and, consequently, climate variations in an inner platform environment with patterns and isolation changes, allows us to establish 4 major orders of periodicity related to orbital components:- The large cycles ob bed thickness variation, constituted by 31-32 beds, recording the 400 ky eccentricity cycle component;- The medium cycles, represented by byndles of 8-9 beds, related to the 100 ky eccentricity cycle component; - The small cycles, of 3-5 beds, recording the 41 ky obliquity components;- The very small cycles, of 2 beds, related to the 22 ky and 26 ky precession components. The mean duration of each bed is around 11.8 ky, a number very close to that of the precession hemi-cycle. Climatic control on qualitative production is confirmed by the close relation between the bed thickness variations, the insolation variability and the variation of micritized elements concentrations.

Evaluation of mechanical soft-abrasive blasting and chemical cleaning methods on alkyd-paint graffiti made on carbonate stones

In the context of this dissertation several studies were developed resulting in submission and publication “Evaluation of mechanical soft-abrasive blasting and chemical cleaning methods on alkyd-paint graffiti made on calcareous stones” to Journal of Cultural Heritage. (http://dx.doi.org/10.101 /j.culher.2014.10.004)

Biomimetic mineralization: encapsulation in calcium carbonate shells

Calcium carbonate biomineralization is a self-assembly process that has been studied to be applied in the biomedical field to encapsulate biomolecules. Advantages of engineering mineral capsules include improved drug loading efficiencies and protection against external environment. However, common production methods result in heterogeneous capsules and subject biomolecules to heat and vibration which cause irreversible damage. To overcome these issues, a microfluidic device was designed, manufactured and tested in terms of selectivity for water and oil to produce a W/O/W emulsion. During the development of this work there was one critical challenge: the selective functionalization in closed microfluidic channels. Wet chemical oxidation of PDMS with 1M NaOH, confirmed by FTIR, followed by adsorption of polyelectrolytes - PDADMAC/PSS - confirmed by UV-Vis and AFM results, render the surface of PDMS hydrophilic. UV-Vis spectroscopy also confirmed that this modification did not affect PDMS optical properties, making possible to monitor fluids and droplets. More important, with this approach PDMS remains hydrophilic over time. However, due to equipment constrains selectivity in microchannels was not achieved. Therefore, emulsion studies took place with conventional methods. Several systems were tried, with promising results achieved with CaCO3 in-situ precipitation, without the use of polymers or magnesium. This mineral stabilizes oil droplets in water, but not in air due to incomplete capsule formation.