Jacuzzis naturais (potholes) na proposta Geoparque Cachoeiras do Amazonas: origem, evolução e estratégias de geoconservação

Abstract

In 2012, it was proposed to create the Cachoeiras do Amazonas Geopark, a territory for the preservation and promotion of geodiversity in the municipality of Presidente Figueiredo (AM). The current proposal includes 18 geosites and 2 geodiversity sites, mainly distributed in geoforms in the Silurian sandstones of the Nhamundá Formation, in the Amazonas Basin. However, studies on karst features, especially the potholes, are still limited, and there is a lack of initiatives for the quantification, sustainable use and promotion of local geodiversity, especially in the involvement of interest groups in the territory. However, studies on karst features, especially marmite, are still limited, and there are few initiatives to quantify, sustainably use and promote local geodiversity, especially when it comes to involving local interest groups. Throughout the territory's drainages, there are marmitas, some of them large (locally called natural jacuzzis), more than 6 m deep. These features are of interest both for their geotourism potential and for the processes involved in their formation. The presence of these structures in siliciclastic rocks raises questions about the erosive mechanisms involved in their generation and evolution, especially in a geological context where classic karst processes are less common. To this end, a structural assessment was carried out, identifying structures and lineaments that can influence the formation of the marmitas; a morphometric analysis, measuring and statistically treating the dimensions of these geoforms; and geodiversity, with a quantitative assessment for tourism, educational and scientific purposes in the places where marmitas occur, with the aim of understanding their origin and evolution, as well as supporting geoconservation strategies. The results of the research generated two scientific articles. The first, published in the Journal of South American Earth Science under the title “Potholes and shear zones deformation in sandstones: Central Amazon Basin”, highlights the influence of neotectonics on the scale, geometry, orientation and dimensions of the potholes, correlating them with microscale arenitization processes. The second, entitled “Origin and Evolution of Natural Jacuzzis (Marmitas) in Presidente Figueiredo (AM): Utilization of Exocarsts for Preservation of the Natural Environment in the Cachoeiras do Amazonas Geopark Proposal” submitted to the Geonorte Magazine dissects the origin of marmitas and their evolution into natural jacuzzis, qualifies the geodiversity in the places of occurrence, and proposals, together with tourist guides, strategies for geoconservation of the exocárstic features through interpretive panels of the sites evaluated. The panels were made available to the town hall and could be used as a tool for geoconservation of the geoforms and as a means of disseminating geosciences to visitors to the town.