Sylvia Anjos

Authigenesis of amphibole and its relationship to the diagenetic evolution of lower cretaceous sandstones of the Potiguar rift basin, northeastern Brazil

Abstract Authigenic amphibole occurs in the fan-delta-front arkoses and lithic sandstones of the Neocomian Pendencia Formation in the Potiguar rift basin, northeastern Brazil as overgrowths, fracture-healing and replacement of detrital amphibole. The amphibole, which is closely associated with diagenetic albite, chlorite and sphene, has precipitated from K—Na—Cl brines enriched in Ti—Fe—Mg, at temperatures ⩽100°C. These ions were derived from the diagenetic alteration of detrital amphibole and pyroxene, chloritization of volcaniclastic sediments at the base of the formation, and from brines that ascended along faults from the underlying basement.

Community Perceptions for Geoconservation of a Coastal Area in Rio de Janeiro, Brazil

We collected socio-environmental data from the inhabitants of a coastal area in the State of Rio de Janeiro, Brazil, in order to investigate the local knowledge about environmental, economic and cultural particularities of the area and the main human activities that impact the environment. Community perceptions from 11 localities in the Região dos Lagos were evaluated. The data analysis can help in the development of specific geoconservation activities for the study area, which is located in the aspirant Geopark ‘Costões e Lagunas do Rio de Janeiro’. This initiative of considering community perceptions can help to maintain and protect local geological sites, raise public awareness of environmental matters and help to manage the development of the new Geopark. Furthermore, it can also contribute to the sustainable development of the area and to the planning of effective policies to sustain progress. Taking into consideration the answers and needs of the interviewed communities, the key topics requiring geoconservation activities in the study area are land use planning and biodiversity, urban mobility, continuous monitoring strategy, environmental awareness, wastewater, urbanisation, geotourism, sense of place, waste and economical activities.

Targeting Sustainability Issues at Geosites: a Study in Região dos Lagos, Rio de Janeiro, Brazil

The aim of this study is to assess sustainability issues for a number of geosites in a study area of Região dos Lagos in the state of Rio de Janeiro, Brazil. The area within the proposed Geopark ‘Costões e Lagunas do Rio de Janeiro’ is well-known for its natural environment with unusual cliffs and hypersaline lagoons, some of them containing stromatolites. We have evaluated the changes in land use and land cover in this coastal area of Brazil over the last four decades and their relation to anthropogenic activities in the area. Land use change statistics indicate that the urban areas have increased to the detriment of the natural vegetation and salt pans. Local knowledge of sustainability issues were considered in order to identify the main threats to and protection needs of the geosites. The sustainability issues comprise environmental awareness, land-use planning and biodiversity protection. The geosite identified with the best sustainability is São Mateus Fort. The geosites found to be the most threatened are Brejo do Espinho, Peró Dunes, Lagoa Vermelha and Mangue de Pedra. Educational projects have been implemented in urban and rural areas of Região dos Lagos to teach the local population the importance of geosites and sustainable development.