Fernando Figueiredo

A multi-method high-resolution geophysical survey in the Machado de Castro museum, central Portugal

Restoration of historical buildings is a delicate operation as they are often built over more ancient and important structures. The Machado de Castro Museum, Coimbra, Central Portugal, has suffered several interventions in historical times and lies over the ancient Roman forum of Coimbra. This building went through a restoration project. These works were preceded by an extensive geophysical survey that aimed at investigating subsurface stratigraphy, including archeological remains, and the internal structure of the actual walls. Owing to the needs of the project, geophysical data interpretation required not only integration but also high resolution. The study consisted of data acquisition over perpendicular planes and different levels that required detailed survey planning and integration of data from different locations that complement images of the surveyed area. Therefore a multi-method, resistivity imaging and a 3D ground probing radar (GPR), high-resolution geophysical survey was done inside the museum. Herein, radargrams are compared with the revealed stratigraphy so that signatures are interpreted, characterized and assigned to archeological structures. Although resistivity and GPR have different resolution capabilities, their data are overlapped and compared, bearing in mind the specific characteristics of this survey. It was also possible to unravel the inner structure of the actual walls, to establish connections between walls, foundations and to find older remains with the combined use and spatial integration of the GPR and resistivity imaging data.

Structural analysis of the Serra da Boa Viagem stratigraphic series (Central Portugal): preliminary study

Los braquiopodos retzidinos son una fraccion menor de las faunas devonicas de la CordilleraCantabrica (Norte de Espana). Aparte de un par de formas raras, impublicadas, del Praguiense delDominio Palentino y del Emsiense inferior del Astur-Leones, proximas al genero Rhynchospirina, ellinaje alcanzo su maximo de diversidad en la parte superior del Emsiense, con dos especies del generoRetzia, R. adrieni y R. cf. prominula, Cooperispira subferita y, quizas, una forma impublicada dePlectospira. El grupo no es conocido en el resto del Devonico y reaparece en el Pensilvaniense con algunasformas del genero Hustedia. En este trabajo se propone un nuevo taxon de la Familia Retziidae,Argovejia n.gen., de la parte final del Emsiense superior de Asturias y Leon, constituido por su especietipo,A. talenti n.sp. y, quizas, por las formas del Emsiense superior del Macizo Armoricano (Francia)Retzia haidingeri var. armoricana y Retzia haidingeri var. dichotoma.The Ronda Depression is filled by Neogene sediments on the boundary between Subbeticreliefs, with NE-SW structural trends, and the frontal Subbetic Chaotic Complexes. The folding stylein the Subbetic Units of Western Betics is strongly controlled by the rheology of the rocks: thick andmassive beds of Jurassic limestones over Triassic marls and gypsum with plastic behaviour. Main deformationstructures in the sedimentary infill of the Ronda depression are simultaneous box folds withNNE-SSW and WNW-ESE trends that only affect its southwestern part. This distribution of folds isa consequence of the inherited fold trend that affected the basement during Early Burdigalian age.

High Resolution Geophysics Inside Machado de Castro Museum – Coimbra, Centre Portugal

Geophysics has been used inside Machado de Castro Museum buildings (Coimbra, Portugal) to guide archeological surveys and to help building restoration. The high resolution geophysical work consisted on GPR and Resistivity survey. Data was gathered on the floor of the so called Renaissance room and on the Cryptoporticus wall, that is, perpendicular to the plane of the Renaissance room floor. Restoration works in old buildings is a sensitive task as they often lay over older buildings. Therefore, high accuracy is demanded to non invasive exploration works. Hence, the geophysical survey was designed in order to obtain very high accuracy. Both the geophysical data/interpretation and the archeological findings were organized in a GIS to provide a full picture of the area under investigation. Archeological excavations confirmed the geophysical findings as well as the accuracy obtained.

UPGRADING OF DISCHARGE RATES USING GEOPHYSICAL AND STRUCTURAL ANALYSIS: SANGEMIL SPA (CENTRAL PORTUGAL)

Sangemil spa area is located 16 km south of Viseu, Central Portugal, near the Dao river. The productive wells, F1 and F2 are located in the alluvial plain of the river and have been threatened by the river floods (Fig. 1). In order to locate new production wells, out of the alluvial plain and close to the spa unit the surrounding geological structure was surveyed. The proposed structural model claimed for a geophysical survey with two profiles P1 and P2 (Fig. 1) using dipole-dipole array. Taking into account the results obtained, three new wells HDN1, HDN2 and HDN3 (Fig. 1), have been drilled (85 to 112m deep). The field measurements of conductivity, temperature, pH and yield are discussed in conjunction with the geophysical results.

Contamination plume evaluation of two ditches using frequency domain electromagnetic method

The study site is located at 6 km NW of Coimbra, central Portugal, near two ditches: North ditch and the old Mondego river bed (Fig. 1). These ditches have been receiving sewage water from Coimbra municipality, causing severe environmental problems, such as ground-water contamination. This contamination is affecting agricultural and arboretum activities, which are the main use of the surroundings areas. In this area, the upper bedrock is of Cretaceous age and consist of siliciclastic sediments, limestones and marls, overlaid by recent sediments of the Mondego river. A geophysical survey, using electromagnetic method in frequency domain, was made near the two ditches with contaminated water. The purpose of this survey is to obtain information about the location of the conductive plume induced by organic and chemical pollution. This information will be used to locate fresh water aquifers, in order to provide the suitable location sites of water wells drilling.