The first record of Hirnantian Ostracoda in South America: implications for the biostratigraphy and paleozoogeography of the Paraná basin

Herein is reported the first occurrence of ostracodes from the Iapó Formation, an uppermost Ordovician unit of the Rio Ivaí Group in the Paraná basin, Brazil. Two ostracode species were identified in the Três Barras Farm section: Harpabollia harparum (Troedsson, 1918) and Satiellina paranaensis Adôrno and Salas in Adôrno et al., 2016 were recovered from dropstone-bearing shale overlying glaciogenic diamictites, a feature typical of Hirnantian (uppermost Ordovician) strata throughout Gondwana. The taxonomy of the Genus Harpabollia, as well as its type species Harpabollia harparum, was reviewed, and emended and new diagnoses were respectively proposed for each taxon. Occurrences of Harpabollia harparum and Satiellina species were common in areas influenced by cold waters. Additionally, the occurrence of Harpabollia harparum, an index species to the uppermost Ordovician of several stratigraphic units in Baltica and southern Gondwana, allowed us to infer a Hirnantian age for the deposits of the Iapó Formation. Other than being associated with Harpabollia harparum in Iapó Formation of the Paraná basin, Satiellina paranaensis is also found in lower levels of the Vila Maria Formation; therefore, these are also considered Hirnantian in age. Above these lower levels of the Vila Maria Formation, a well-dated Rhuddanian (lowermost Llandovery, Silurian) palynomorph assemblage is observed within the formation. These occurrences are evidence of a continuous process of sedimentary deposition during the Ordovician–Silurian transition in the Paraná basin.

Structural, hydrogeological and hydrochemical characterization of aquifers in the Paraná Basin: An integrated literature review

The Paraná Basin in Brazil is of vital importance and because of a large groundwater reservoir and the high exploitation of this resource by the population a structural and hydrogeochemical knowledge is needed. Objectives: 1) Analyze studies that address the structural, hydrogeological and hydrochemical characterization of aquifers in the Paraná Basin; 2) Highlight the main techniques used in the respective studies and the scientific development arising from the use of these techniques for a better hydrochemical and structural understanding of the Paraná Basin. Methodology: Tracing lineaments from satellite image and field work are the main techniques used for structural characterization. For hydrochemical analyses, factorial methods physical-chemical analyses are used. Results: the most common chemical types of groundwater that circulate in the sedimentary and volcanic units of the Paraná Basin, which include the Pirambóia, Irati, Rio Bonito, Botucatu and Serra Geral formations are calciumbicarbonates, calcium-magnesian bicarbonates, calcium-sodium bicarbonates and sodium-sulphate-chloride bicarbonates. Sodium-sulfated waters are not found in the Serra Geral Formation, except when they come from the sedimentary units. Sodium and sulfate are not expected ions in basalt weathering, and therefore a greater understanding is needed on structural communication by means of faults that occur between the Serra Geral Aquifer System (SGAS) and the mesozoic and permian sedimentary aquifers and aquitards that contribute for unexpected ions in the SGAS. Conclusion: The Paraná Basin is a reason for interest in geological studies in Brazil because of its link to several areas of interest in geosciences, which include hydrochemistry, stratigraphy, paleontology and hydrogeology.

3D implicit modeling applied to the evaluation of CO2 geological storage in the shales of the Irati Formation, Paraná Basin, Southeastern Brazil

The Paris Agreement established global ambitious targets for reducing carbon dioxide (CO2) emissions, requiring the rapid and extensive development of low carbon technologies, and one of the most efficient is CO2 geological storage. Among the deep geological formations used for CO2 storage, the shale layers have been a new emerging topic showing to be efficient because they are abundant and have a high content of organic matter, being favorable for CO2 retention. However, one of the challenges in evaluating a location for possible reservoirs is the adequate geological characterization and storage volume estimates. This research evaluated the Irati Formation of the Paraná Basin, through the information from hydrocarbon exploration wells in Southeastern Brazil, where most stationary sources of carbon emissions are located. Three-dimensional (3D) implicit modeling techniques were applied not only for the volume calculation purpose, but also in the site selection stage, generating thematic 3D models of thickness, depth, structures, and distance to aquifer systems. The limestones, shales, and black shales of the Irati Formation were locally divided into six units according to geological composition and spatial continuity. The E black shale unit was considered for CO2 geological storage indicating a theoretical capacity of 1.85 Gt of CO2. The potential of the achieved capacity is promising not only for been greater than the total of CO2 locally produced but also for supporting the implantation of new projects in this region.