http://hdl.handle.net/10174/14425 2026-03-23T08:45:21Z 2026-03-23T08:45:21Z Araújo, J. Fonseca, R. Albuquerque, T. Mota Silva, N. Silva, R. http://hdl.handle.net/10174/40975 2026-02-09T17:42:03Z 2025-03-31T23:00:00Z

Title: Influence of sulphide mine tailings on drainage water quality, 60 years after its abandonment. A case study in SW Portugal Authors: Araújo, J.; Fonseca, R.; Albuquerque, T.; Mota Silva, N.; Silva, R. Abstract: The GeoMatRe project aims to find low-cost solutions for water and sediment rehabilitation using raw geomaterials, in abandoned mines of the Iberian Pyritic Belt. One of our case studies is the Caveira mine in southwestern Portugal, where large piles of mining waste, containing significant amounts of metals, record the long history of its exploitation for gold (Au) and silver (Ag). After the exhaustion of its reserves, the extraction of the remaining metals (cooper (Cu), lead (Pb) and zinc (Zn)) and sulphur (S) continued, until its abandonment during the 60s of 20th century. This work has two objectives: (i) to study the influence of mine and mine tailings drainage on water quality by analysing the dissolved and particulate material in drainage waters, and (ii) to determine whether there are differences in the contamination level of these waters according to the different weather conditions of the last two winters

2025-03-31T23:00:00Z Silva, R. Fonseca, R. Araújo, J. Silva, N. Albuquerque, T. http://hdl.handle.net/10174/40937 2026-02-09T12:41:21Z 2025-03-31T23:00:00Z

Title: Evaluation of the level of contamination in sediments from watercourses of the Caveira Mining System (Grândola) Authors: Silva, R.; Fonseca, R.; Araújo, J.; Silva, N.; Albuquerque, T. Abstract: The following work is inserted in the GeoMatRe Project, in which the conditions of the most updated physical and chemical parameters of an Acid Mine Drainage are analysed. This study shows that the mining area of Caveira, in Grândola, Portugal, which was abandoned since the 60’s, presents a critical situation of contamination, with high levels of Potentially Toxic Elements (PTE) present in the whole mining area and its surroundings. It is intended, within the scope of the project, and through geochemical analysis, to observe the conditions of contamination by PTE in native sediments from the mine tailing, which occur either in mobile phases, dissolved in the interstitial water of the sediments, or in more immobile phases. With that in mind, preparation of methodologies for geochemical studies were carried out, namely Fusion for further analysis of the element’s total forms, and Partial Digestion with Aqua Regia for quantification of the most easily extratable forms, which represent the most contaminating fraction. Ultimately, Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) was used to analyse and quantify the previously prepared samples. It is herein presented a general characterization of the mining system, through analysis and understanding of the Geo-accumulation Index (IGEO) and the Enrichment Factor (EF), tools that improve the visualization of the previously obtained data on the ICP-OES, demonstrating the content and chemical nature of the contaminating elements (As, Cu, Zn, Pb and Hg) as main PTE’s in the region, presenting values, in some cases, thousands of times higher than those stipulated by Nacional standards.

2025-03-31T23:00:00Z Tereso, V. Dias, R. Roseiro, J. Romão, J. Coke, C. Fonseca, R. Ribeiro, A. http://hdl.handle.net/10174/40865 2026-02-05T15:31:34Z 2025-01-01T00:00:00Z

Title: Ordovician – Silurian transition in the Central-Iberian Zone: Just a stratigraphic boundary or a major element in the evolution of the Iberian Variscides? Authors: Tereso, V.; Dias, R.; Roseiro, J.; Romão, J.; Coke, C.; Fonseca, R.; Ribeiro, A. Abstract: The Ordovician-Silurian boundary in the Central-Iberian Zone is often considered a normal stratigraphic transition. Nevertheless, in studies carried out in Portugal (e.g. Espinhosela, São Mamede and Buçaco areas) and Spain (e.g. Alcañices Synform) this contact is marked by the development of shear zones subparallel to the lithostratigraphic units. Ongoing structural mapping in Celorico de Basto (Marão region) shows that near Campanhó, the Ordovician (Pardelhas Formation) and the Silurian (Campanhó Formation) units are bounded by a regional shear zone with a normal kinematics (the Covelo do Monte Fault, here presented). Although their origin is debatable, the intraorogenic normal faults are common mechanisms active during Variscan times in the Central-Iberian Zone. In the case of the Ordovician- Silurian boundary, these detachments could be facilitated by shale and organic materials prone to control the development of shear zones.

2025-01-01T00:00:00Z Costa, Oscar Marinho Reis, Paula Nogueira, Pedro Pimenta Simões, Pedro Kumholea, António http://hdl.handle.net/10174/39599 2025-11-17T01:07:44Z 2025-01-01T00:00:00Z

Title: Mineralogical and geochemical characterization of surface soils and waste piles collected in the Preguiça-Vila Ruiva mining area Authors: Costa, Oscar; Marinho Reis, Paula; Nogueira, Pedro; Pimenta Simões, Pedro; Kumholea, António Abstract: The Preguiça and Vila Ruiva mines, located in the Ossa Morena Zone, Beja district, were explored for Fe-Zn-Pb in the early and mid-20th century. This study aims to reassess their mining potential by creating geochemical maps using modern exploration techniques combined with petrographic and mineralogical analyses. These maps resulted from field measurements obtained by portable X-ray fluorescence (XRF-P) equipment. The geochemical mapping shows that the Zn, Pb, and Fe anomalies correspond to the waste rock piles presenting, however, variations in their spatial distribution. Spatially concordant anomalies of Fe, Co, Cr, and V were detected in the soil NW of the Preguiça mine.

2025-01-01T00:00:00Z