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Ash fall layers and vitroclastic-carrying sediments distributed throughout the entire Permian stratigraphic range of the Parana Basin (Brazil and Uruguay) occur in the Tubarao Supergroup (Rio Bonito Formation) and the Passa Dois Group (Irati, Estrada Nova/Teresina, Corumbatai, and Rio do Rasto Formations), which constitute the Gondwana 1 Supersequence. U-Pb zircon ages, acquired by SHRIMP and isotope-dissolution thermal ionization mass spectrometer (ID-TIMS) from tuffs within the Mangrullo and Yaguari Formations of Uruguay, are compatible with a correlation with the Irati and parts of the Teresina and Rio do Rasto Formations, respectively, of Brazil. U-Pb zircon ages suggest maximum depositional ages for the samples: (1) Rio Bonito Formation: ages ranging from 295.8±3.1 to 304.0±5.6 Ma (Asselian, lowermost Permian), consistent with the age range of the Protohaploxypinus goraiensis subzone; (2) Irati Formation: ages ranging from 279.9±4.8 to 280.0±3.0 Ma (Artinskian, Middle Permian), consistent with the occurrence of species of the Lueckisporites virkkiae zone; (3) Rio do Rasto Formation: ages ranging from 266.7±5.4 to 274.6±6.3 Ma (Wordian to Roadian, Middle Permian). All the SHRIMP U-Pb zircon ages are consistent with their superimposition order in the stratigraphy, the latest revisions to the Permian timescale (International Commission of Stratigraphy, 2018 version), and the most recent appraisals of biostratigraphic data. The ID-TIMS U-Pb zircon ages from the Corumbatai Formation suggest that U-Pb ages may be >10% younger than interpreted biostratigraphic ages.

Tropidoleptus was a genus of brachiopods that had a very peculiar morphology and occurred in the Devonian period (about 419–358 million years ago) throughout the world. Although there have been reports of the presence of this genus in the Paraná Basin (Brazil) since the nineteenth century, its actual occurrence has been the subject of much debate. The objective of this work was to clarify this situation. For that, dozens of specimens from the Brazilian state of Mato Grosso were analyzed. The studied samples have typical characteristics of Tropidoleptus, therefore this genus actually also occurred in the Paraná Basin. Tropidoleptus possibly arrived in the Paraná Basin 385 million years ago, at the moment when there was a marine connection among the Brazilian Paraná, Parnaíba, and Amazonas basins. The occurrence of Tropidoleptus can be used as a marker of shallower marine environments, and in the Paraná Basin in particular, it can indicate that the rocks, where they are present, are less than 390 million years old. Tropidoleptus is a brachiopod genus with a very peculiar morphology that existed throughout the Devonian as a cosmopolitan taxon. Although there have been reports of the presence of this genus in the Paraná Basin since the nineteenth century, its actual occurrence has been the subject of much debate. The objective of this paper was to clarify this situation. For this purpose, dozens of specimens from Monjolo dos Padres and Juscimeira outcrops (São Domingos Formation, possibly Givetian) in the Brazilian state of Mato Grosso were analyzed. The samples studied here exhibit the typical characteristics of Tropidoleptus, confirming that this genus also occurred in the Paraná Basin. It is possible that Tropidoleptus entered the Paraná Basin during the Eifelian/Givetian from the Amazonas and/or Parnaíba basins (Brazil), during a period of warm-water transgression. When Tropidoleptus is found in situ, it can serve as an indicator of a shallower water environment (shoreface to shallower portions of transitional offshore). In the Paraná Basin, its presence can indicate rocks no older than the Eifelian–Givetian transition.

The formal description of a liverwort from the Paraná Basin is presented. The fossil was found in the Rio Bonito Formation, Early Permian (Sakmarian), and is identified as a new species of the genus Hepaticites, named H. iporangae n. sp. The samples studied were collected from the macrofossil-rich roof-shale layer of the Quitéria Outcrop in the municipality of Encruzilhada do Sul, state of Rio Grande do Sul, Brazil. H. iporangae is one of the oldest liverworts reported from South America. The fossil described here provides more evidence of the relative diversity of liverworts in Paleozoic Gondwana despite the severe climatic conditions during the glaciations of the Permo-Carboniferous.

The quantum technology absolute gravimeters, gradiometers, and clocks are at the forefront of the instrumentation to be exploited in a future gravity mission (the QSG mission concept). Apart from the quantum payload, the mission design defines the choice of the number of satellites and the satellite orbit constellation, with the goal of optimizing the observation of the earth’s gravity field and reducing aliasing phenomena. Our goal is to define the realistic gravity field changes generated by glaciers and lakes and define the sensitivity of the quantum gravity mission for the detection of hydrologic and cryospheric mass changes. The analysis focuses on mass changes in the high mountains of Asia and the South American continent. The mass changes are based on terrestrial and satellite observations and are of a climatic origin. We show that compared to the existing GRACE-FO mission, a quantum gravity mission significantly improves the detection of the climatic mass gain of lakes and mass loss of glaciers, allowing for smaller mass features to be distinguished, and smaller mass losses to be detected. The greater signal is the seasonal signal with a yearly period, which would be detected at the 10 Gt level for areas > 8000 km2. The yearly mass loss of the Patagonian glaciers can be detected at the 5 Gt/yr level, an improvement from the 10 Gt/yr detectable by GRACE-FO. Spatial resolution would also be improved, with an increase of about 50% in spatial frequency for the detection of the mass change rate of lakes and glaciers in Tibet. The improved spatial resolution enables an improved localization of the lakes and glaciers affected by climatic mass change. The results will contribute to defining the user requirements of the future QSG missions.

The Permian Rio do Rasto Formation (Paraná Basin) crops out in southern Brazil and was deposited under fluvio-lacustrine settings. A singular outcrop located in the Aceguá municipality (Rio Grande do Sul State) represents a sequence of three distinct levels of paleosols in which rhizoliths and a single vertebrate burrow were recovered. The latter has a sub-vertical orientation, a slightly curved shape and a gross morphology and simple architecture that are consistent with aestivation burrows produced by lungfishes. The occurrence of this structure, in association with the features of the paleosols, indicates a seasonal climate with drought events. Additionally, a tonstein layer is interbedded in the paleosol sequence, indicating the influence of volcanic ash falls in the paleoenvironment. Zircons were collected from this level and dated using U-Pb techniques and the obtained age is 270.61 +1.76/-3.27 Ma (Roadian). The paleoenvironmental context of this outcrop is in accordance with a dry, seasonal climate of southwestern Pangaea during the early Guadalupian.

Ascocerid cephalopods are described for the first time from high paleolatitudes of Gondwana. Studied material was collected from the Hirnantian?–Llandovery strata of the Eusebio Ayala and Vargas Peña formations, Paraná Basin, southeastern Paraguay. The specimens are poorly preserved and were questionably assigned to the subfamily Probillingsitinae Flower, 1941, being undetermined at genus and species rank because diagnostic characters are not visible. A particular feature seen in our material is the presence of both parts of the ascocerid conch (the juvenile or cyrtocone and the mature or brevicone) joined together, which is a very rare condition in the known paleontological record. The specimens are interpreted as at a subadult stage of development because fully grown ascocerids would have lost the juvenile shell. A planktonic vertical migrant mode of life with a subvertical attitude is proposed for the juvenile, and a horizontal demersal nektonic mode for the adult form, as has been previously suggested. A subvertical orientation near the bottom is proposed for the subadult stage. We suggest that the immigration of ascocerids to southwestern Gondwana was possible through ocean currents that would carry the planktonic juveniles from low to high latitudes during the end-Ordovician postglacial transgression that flooded the intracratonic basins of the region.

This study tests the presence of differential preservation in the Devonian Malvinokaffric fauna from the Chapada Group (Paraná Basin, Brazil). Results of EDXRF, EDS, Raman Spectroscopy, and petrographic analyses show differential preservation of shells that were originally calcite as hematite and goethite fossils, while organisms with original calcium phosphate shells tend to be preserved inside phosphatic concretions. Both preservation types are commonly associated with pseudoframboids, while calcium sulfate minerals are commonly associated with hematized fossils. From this evidence, a diagenetic model for these fossils is proposed. The model includes an early diagenetic phase (characterized by anaerobic sulfate reduction and precipitation of pyrite and carbonate-fluorapatite) and a second, near-surface chemical weathering phase (characterized by the oxidation of pyrite and precipitation of iron oxyhydroxides and calcium sulfates). Acidic conditions in both phases may account for the dissolution of less stable minerals compared to calcium phosphate. It is considered that this model may assist in understanding other similarly preserved biotas, as well as enhancing understanding of the taphonomic overprint that may occur within this important and endemic Devonian biota.

In South America, the introduction of peacock-bass (Cichla), a voracious predator fish, has been an underestimated threat for native fish communities. Although this predator is widespread in many reservoirs, few studies have explored its impact on biodiversity. To investigate the relationship between invasion and fish diversity, the present study followed a natural experiment in the Rosana Reservoir (Paraná River basin), where Cichla kelberi were introduced in 2004. We monitored fish assemblages associated with submerged macrophytes between 2003 and 2007, using a 1 m² throw trap. In the years following the introduction, fish diversity dramatically changed. For example, in March 2007, mean fish density and richness were reduced by ca. 95 and 80%, respectively, and many small-sized species had vanished. One aspect was the gradual change of biodiversity, which unfolded at two times during each year: (1) impacts during summer/autumn periods, which coincided with large shoals of young C. kelberi in the patches; and (2) assemblage recovery during the spring. The sequence of extinction-colonization events, however, might not be able to maintain fish assemblages due to the decrease in recovery intensity each spring; assuming a constant decline rate in the coming years, we predict complete assemblage extinction by the summer of 2010. Results from this natural experiment provided evidence supporting the collapse of fish assemblages soon after the introduction of C. kelberi. Such rapid destruction (2 years) reveals an important homogenizing force behind this predator and stresses the need for control measures that prevent new transferences among South American basins.

The Serra Geral Aquifer System (SGAS) has great potential for exploring its waters. However, high salinity values are found in certain regions. This higher than expected salinity is due to the connection between hydroestratigraphic units under the SGAS, such as the Guarani aquifer system (GAS) and Permian aquitards and aquifers, such as Irati and Rio Bonito. The principal components analyses included the K-means method and dendrogram analyzed together with a map of structural faults and simulation which resulted in the analysis of preferential directions for the flow of groundwater and which are the main faults that contribute to the decrease in potentiometry in the SGAS, which allow ions such as sodium and sulfate to rise to the SGAS from GAS and pre-GAS sedimentary units. The simulation helped to indicate the areas with the highest salinity and which coincided with the major regional faults. The study area was divided into five zones, based on large regional faults. The objective is to characterize which regional faults are important for communication between these aquifers systems and to identify the areas where the highest salinities occur, which are directly correlated with the potentiometry of SGAS and GAS that must match for high salinity values to occur. This communication is very evident through simulation techniques and the study of SGAS and GAS potenctiometric isohypses. The analysis of the fracturing degree of minor faults associated with major faults also determines the places where the rise of saline waters is possible, because these major faults lower the potentiometric levels of GAS.

Species of the genus Pimelodella (Eigenmann & Eigenmann, 1988) present many similar morphological characteristics, which makes taxonomic identification difficult. Some species present morphological distinction and reproduce normally, while others present reproductive isolation without morphological distinction. Taking that into consideration, we used starch-gel electrophoresis of enzymes to compare two species of the genus Pimelodella collected in Paraná, Ivaí and Pirapó rivers of the Upper Paraná River basin. We analyzed the liver and muscle tissue of 82 Pimelodella avanhandavae and 29 Pimelodella gracilis individuals, which revealed few genetic differences between species. In addition, we carried out an experimental design based on the separation of four populations: P. avanhandavae, Parana River (n = 37); P. avanhandavae, Ivaí River (n = 6); P. gracilis, Ivaí River (n = 29); P. avanhandavae, Pirapó River (n = 39). The high proportions of polymorphic loci as well as the expected heterozygosity suggest that both species have high genetic variability. Nei’s genetic identity values and Wright's fixation indices revealed a large genetic proximity between the samples collected in Ivaí and Pirapó rivers, regardless of the species analyzed. The presence of fixed alleles at one hundred percent for two loci showed that P. avanhandavae individuals collected in the Parana River are genetically distant from all remaining populations. Data indicated that P. avanhandavae, collected in this river, constitutes a distinguished species from those collected in Ivaí and Pirapó rivers. Therefore, we suggest, that more studies with molecular markers be carried out with the genus, as well as a review of the diagnostic morphological characteristics used to separate P. avanhandavae from P. gracilis.