Daniel P. S. Oliveira

Mineralogy and geochemistry of tin- and germanium-bearing copper ore, Barrigão re-mobilized vein deposit, Iberian Pyrite Belt, Portugal

The Barrigão re-mobilized copper vein deposit, Iberian Pyrite Belt, southern Portugal, is located about 60 km south of Beja and 10 km southeast of the Neves Corvo ore deposit, in Alentejo Province. The deposit is structurally associated with a NE–SW striking fault zone inferred to have developed during late Variscan deformation. The copper ore itself is a breccia-type ore, characterized by up to four ore-forming stages, with the late stages showing evidence of fluid-driven element re-mobilization. The ore is dominated by chalcopyrite + tennantite-tetrahedrite, with minor arsenopyrite, pyrite, and löllingite. The supergene paragenesis is composed mainly of bornite, covellite, and digenite. Whole-rock analyses show anomalous tin and germanium contents, with averages of 320 and 61 ppm, respectively. Electron microprobe analysis of Barrigão ores revealed the germanium and tin to be restricted to chalcopyrite, which underwent late-stage hydrothermal fluid overprint along distinct vein-like zones. The measured zonal enrichment of tin and germanium is related to limited element re-mobilization associated with mineral replacement, which resulted in distinctive mineral disequilibrium. Fluid-driven element zoning affected chalcopyrite and tennantite coevally. The average contents of germanium and tin in chalcopyrite are of 0.19 and 0.55 wt.%, respectively, as confirmed through additional micro-proton-induced X-ray emission (micro-PIXE) analysis. The distribution of tin and germanium in chalcopyrite correlates strongly with iron. Tin and germanium covary. Minute sub-microscopic inclusions of an unknown Cu–Sn–Ge sulphide phase have been detected in chalcopyrite and in small vugs therein. These inclusions hint at a stanniferous sulphide as the most possible host for tin and germanium in chalcopyrite, although the idea of limited incorporation of these two elements through element substitution cannot be completely excluded.

Integration of Geohazards into Urban and Land-Use Planning. Towards a Landslide Directive. The EuroGeoSurveys Questionnaire

Exposure to hazards is expected to increase in Europe, due to rapid population growth in urban areas and the escalation of urbanization throughout many countries. In the framework of the European Geological Surveys (EGS), the Earth Observation and Geohazards Expert Group (EOEG) has carried out a survey based enquiry regarding the integration of geohazards (earthquakes, volcanoes, landslides, ground subsidence, floods and others) into urban and land-use planning. Responses from 19 European countries and 5 regions reveal heterogeneous policies across national borders. 17% of the countries have not yet implemented any legal measures to integrate geohazards into urban and land-use plans and half of the participating countries have no official methodological guides to construct geohazard maps. Additionally, there is a scarce knowledge about real social impacts of geohazards and resulting disasters in many of the countries, although they have a significant impact on their national economies. This overview stresses the need for a common legislative framework and homogenization of the national legislations as well as mutual guidelines which adopt the principles applicable to the management of geohazards and explain the process to be followed in the production of hazard documentation. This is especially relevant in case of landslide and subsidence hazards; although those are of great importance in Europe, there are no common guidelines and practices similar to Directive 2007/60/EC on the assessment and management of flood risk. Based on their expertise, EuroGeoSurveys (EGS) have the potential to coordinate this activity in European geohazard guidelines and to promote the interaction among stakeholders.