Brazilian Basins Research Articles

Generalization of deep learning models for natural gas indication in 2D seismic data

Methods based on Machine Learning and Deep Learning are increasingly popular to help interpret large volumes of data that belong to various areas and seek to fulfill multiple tasks. One of these areas studies seismic data in the search for hydrocarbon reserves, for which Deep Learning models are trained, showing acceptable results for low study data. However, these models present generalization problems. Their performance tends to decrease when used on seismic data from new exploration. This tendency is particularly true for 2D data, which have many features. This work presents a method to improve the generalization of the Deep Learning model for the indication of natural gas in 2D seismic data based on the recommendation of training data and hyperparameter operations of the model. The tests used a database of the Parnaíba basin in northeast Brazil. Experiments showed an increase in the correct indication of natural gas that varies according to the metric 8%≤Recall≤37%, with a fluctuation in the increase of false positives of −2%≤Precision≤13%. It is an improvement in the generalization of the Deep Learning model of up to 11% according to the F1 score metric or up to 10% according to the IoU metric.

Performance evaluation of urban drainage systems: an analytic hierarchy process approach for the Jaracati basin in Brazil

The efficiency of drainage systems in urban centers and especially in their peripheral regions has deserved more and more special attention since their interrelationship with social and environmental aspects is associated with the performance of drainage infrastructures. Integrated urban water management is a major factor in the effectiveness of an urban drainage system. In large cities, negative effects caused by the disorderly urbanization process, especially those related to rainwater runoff, are increasingly present. An evaluation model of urban drainage systems was generated using System Fragility Indicators (IFS) and their ranking via Analytic Hierarchy Process (AHP), in the Jaracati River basin, Maranhão State, Brazil. Indicators were measured through the evaluation of the system and the experience of specialists in drainage systems. The results obtained allowed for the consolidation of a model to support planning and decision-making in the assessment processes of measures to mitigate socio-environmental impacts involved in the urban drainage of a watershed, with performance indicators capable of guaranteeing the support of a model being verified measurement of performance parameters of urban drainage systems.

Early Aptian marine incursions in the interior of northeastern Brazil following the Gondwana breakup

This study reports a set of primeval marine incursions identified in two drill cores, 1PS-06-CE, and 1PS-10-CE, which recovered the Barbalha Formation, Araripe Basin, Brazil. Based on a multi-proxy approach involving stratigraphy, microbiofacies, ichnofossils, and microfossils, three short-lived marine incursions were identified, designated Araripe Marine Incursions (AMI) 1–3. AMI-1 and AMI-2, which occur within the shales of the Batateira Beds (lower part of the Barbalha Formation), were identified by the occurrence of benthonic foraminifera, calcareous nannofossils, dinocysts, and a mass mortality event of non-marine ostracods. AMI-3 was recognized in the upper part of the Barbalha Formation, based on the occurrence of ichnofossils and planktonic foraminifera. The observation of the planktonic foraminifera genus Leupoldina for the first time in the basin indicates early Aptian/early late Aptian age for these deposits, and the first opportunity of correlation with global foraminifera biozonation. Our findings have implications for the breakup of the Gondwana Supercontinent, as these incursions represent the earliest marine-derived flooding events in the inland basins of northeastern Brazil.

Reassessing a glacial landscape developed during terminal glaciation of the Late Paleozoic Ice Age in Uruguay

Whalebacks, roche moutonnées, and S-forms carved on Ediacaran granitoids near Cerro de las Cuentas, Uruguay, along with overlying diamictites, siltstones, and sandstones displaying soft-sediment grooved and striated surfaces in the Pennsylvanian San Gregorio Formation, record the glacial to post-glacial transition in the linked Norte, southern Paraná and Chaco-Paraná basins of Uruguay, Brazil, and Argentina respectively. Early authors reported these features resulted from subglacial abrasion and deposition as lodgement tills and glaciotectonites. Our re-examination reveals a nuanced setting with changing ice thicknesses, subglacial kinematics, and ice proximal glaciomarine dynamics associated with advance and retreat of an ice stream, or multiple advances of the Uruguayan Ice lobe, during glaciation of the Late Paleozoic Ice Age (LPIA) in these basins. The preserved landforms indicate temperate glacial conditions. Whalebacks formed under 1.6 to 2.5 km-thick ice and likely formed when the lobe extended across the Uruguayan and Rio Grande do Sul shields into the adjacent Paraná Basin. Previously unidentified m-scale roches moutonnées cut into one whaleback developed under thinner ice where reduced basal pressure allowed for the opening of air and water-filled cavities, thus facilitating quarrying on the lee side of basement bumps. S-forms provide additional evidence for the occurrence of subglacial waters, indicating that the basal ice was at or above its pressure melting point. The lower meter of the overlying strata consists of interstratified trace fossil-bearing, laminated siltstones; thin-bedded diamictites; and current-rippled sandstones. Trace fossils belonging to the Mermia ichnofacies within the basal siltstones, as well as acritarchs in the overlying siltstones, suggest that these sediments were deposited in ice-proximal subaqueous settings with contributions from meltwater discharge. Graded siltstone laminae suggest settling from suspension likely from meltwater plumes, while thin-bedded diamictites were deposited either as debris flows or as two-component sedimentation with fines settling from suspension and coarser particles introduce as iceberg-rafted dropstones. Current-rippled sandstones indicate the occurrence of underflow currents. Soft-sediment troughs, grooves, and striations cutting these sediments display curved and sinuous paths with some features oriented perpendicular, and one oriented opposite to the overall trend. They contain marginal and terminal berms typical of iceberg scour marks suggesting transit across the area by icebergs calving from a tidewater ice front located to the SE.

Exploratory analysis of the water governance frameworks regarding the OECD principles in two river basins in Brazil and Portugal

Water is essential for human and economic development, and ecosystem services. Water crises are primarily governance crises, requiring consideration of multiple scales and actors. This article aims to discuss water governance principles proposed by the Organization for Economic Co-operation and Development (OECD) in 2015 and 2018, in Brazil and Portugal, including an exploratory analysis of the OECD indicators’ framework and those used in the Protocol of the Water Management Observatory (OGA) in Brazil in 2019. The main objective was to identify critical dimensions for an adequate assessment of water governance, and drivers for water policy improvement in both countries.

-I fish, therefore I monitor: Participatory monitoring to assess inland small-scale fisheries.

Analysis of small-scale inland fisheries (SSIFs) is often highly dispersed and tends not reflect the true magnitude of their contribution to society. This is partly due to the insufficient attention given to this sector by the relevant authorities, in addition to its highly diverse characteristics, with complex patterns of operation in a wide range of systems, often in remote areas. Here, by integrating fishers as participatory fishery monitors, we provide fishery-dependent estimates of yields, the biological attributes of the fish species, and the spatiotemporal dynamics of the fisheries of lakes on the floodplain of the São Francisco basin in northeastern Brazil. As the fishers were willing participates in the monitoring, the results revealed well-structured artisanal fishing activities, with the lake system providing high-profile fish harvests from both monthly and annual perspectives. The spatial distribution of fishing effort reflected the adaptation of the fishers to the flood cycle of the river, in order to maintain high fishery productivity throughout the year. The results also indicate that participatory monitoring can help to overcome knowledge gaps and provide a database that is readily applicable to management needs at both local and regional scales. As Brazil is one few world's nations that no longer have national fishing monitoring program, participatory monitoring represents a low-cost solution for the credible and useful data on small-scale fisheries. It would thus appear to be extremely worthwhile to invest in the empowerment of communities in order to overcome the historic vulnerability of productive sector and the food security of the populations that depend on these fisheries.

Hydrochemistry and weathering at Pardo River basin, São Paulo State, Brazil.

This work was conducted at the Pardo River hydrographic basin, which is a federal watershed belonging to the Paranapanema River hydrographic basin (PRHB) in Brazil (São Paulo State and Paraná State). The aim was to realize an integrated hydrochemical and radiometric (U-isotopes and 210Po) approach, highlighting the water/soil-rock and surface water/groundwater interactions, with implications to the weathering processes occurring there. The study area has been often considered one of the best preserved/unpolluted river in São Paulo State, contributing to the water supply of several cities distributed along its banks. However, the results reported here suggest possible lead diffuse pollution caused by the use of phosphate fertilizers in agricultural activities taking place in the basin. The analyzed groundwaters and surface waters tend to be neutral to slightly alkaline (pH of 6.8-7.7), possessing low mineral concentration (total dissolved solids up to 500mg/L). SiO2 is the major dissolved constituent in the waters, while bicarbonate is the dominant anion, and calcium is the preponderant cation. The effects of the weathering of silicates to control the dissolution of constituents in the liquid phase have been identified from some diagrams often utilized in hydrogeochemical studies. Chemical weathering rates have been estimated from hydrochemical data associated to analytical results of the natural uranium isotopes 238U and 234U concerning to samples of rainwater and Pardo River waters. The fluxes in this watershed are permitted to obtain the following rates: 11.43 t/km2 year (sodium), 2.76 t/km2 year (calcium), 3.17 t/km2 year (magnesium), 0.77 t/km2 year (iron), and 8.64 t/km2 year (uranium). This new dataset constitutes valuable information for people engaged on the management of the Pardo River watershed, as well as to researchers interested on comparative studies considering the available data from other basins worldwide.

The Role of Reservoir Reoperation to Mitigate Climate Change Impacts on Hydropower and Environmental Water Demands

Adapting reservoir operation to a changing climate is important to improve water system performance toward benefits including water security, and energy production. However, managers still need to know if and how reoperation can also assist long-term mitigation of climate change impacts on aquatic ecosystems, creating, for example, opportunities to revert fish migration and recruitment losses. This paper investigates the operational adaptive capacity of water systems to mitigate climate change impacts on both hydropower and aquatic ecosystems, with a detailed representation of fish species recruitment response to flow regime changes. The methodology framework combines hydroclimatic modeling, explicit stochastic reservoir operation modeling, and predictive modeling of migratory fish recruitment abundance, illustrated using the large-scale hydropower system of the Paraná River Basin in Brazil. Results identified that operating policies can be adapted to improve hydropower production under a changing climate with drier conditions by 2% to 8% compared with current operating policies. Although insufficient to eliminate all energy losses that climate change may cause, the optimized operation provided flexibility to adjust flow releases and reduce the likelihood of future severe multiyear deficits, which are very harmful to fish populations. Adapting operation to climate change sacrificed fish recruitment performance over a few years of the time horizon to maintain an overall higher storage, but it also improved the chances of producing flow releases in magnitude, timing, and duration during long drier periods that prevented more severe impacts of climate change on fish recruitment and population. This indicates that it might be possible to have synergies in adapting reservoir operation to not only prevent energy losses, but also to improve fish recruitment under climate change. The ecosystem resiliency under adapted operation increased up to 2 times compared with the isolated climate change effect.

Estimating Geomagnetically Induced Currents in Southern Brazil Using 3‐D Earth Resistivity Model

AbstractGeomagnetically induced currents (GICs) result from the interaction of the time variation of ground magnetic field during a geomagnetic disturbance with the Earth's deep electrical resistivity structure. In this study, we simulate induced GICs in a hypothetical representation of a low‐latitude power transmission network located mainly over the large Paleozoic Paraná basin (PB) in southern Brazil. Two intense geomagnetic storms in June and December 2015 are chosen and geoelectric fields are calculated by convolving a three‐dimensional (3‐D) Earth resistivity model with recorded geomagnetic variations. The dB/dt proxy often used to characterize GIC activity fails during the June storm mainly due to the relationship of the instantaneous geoelectric field to previous magnetic field values. Precise resistances of network components are unknown, so assumptions are made for calculating GIC flows from the derived geoelectric field. The largest GICs are modeled in regions of low conductance in the 3‐D resistivity model, concentrated in an isolated substation at the northern edge of the network and in a cluster of substations in its central part where the east‐west (E‐W) oriented transmission lines coincide with the orientation of the instantaneous geoelectric field. The maximum magnitude of the modeled GIC was obtained during the main phase of the June storm, modeled at a northern substation, while the lowest magnitudes were found over prominent crustal anomalies along the PB axis and bordering the continental margin. The simulation results will be used to prospect the optimal substations for installation of GIC monitoring equipment.

Large sampling effort is not related to richness and geographic distribution of Cladocera (Crustacea, Branchiopoda) in the Brazilian Savannah

ABSTRACT The Cerrado is home of the headwaters of some important Brazilian basins. Such biome has a high diversity of animal and plant species with a high degree of endemism. This premise is well documented for microcrustaceans of the Superorder Cladocera, although many areas still need sampling. In this context, the objective of the present investigation was to evaluate the geographic distribution and richness of Cladocera in the Cerrado biome. The analyzed data were obtained from the authors database on Brazilian Cladocera and distributed according to the hydrographic regions comprised in the biome. Species distribution models were used to determine the areas with the highest probability of occurrence of Cladocera. We analyzed 125 publications, resulting in 2829 records. In total, we obtained 161 taxa, belonging to 48 genera and seven families. Regarding the Hydrographic Regions, Paraná presented the highest richness, followed by TocantinsAraguaia and São Francisco. Our result indicates that most studies are concentrated in certain areas. Furthermore, the species distribution models indicated that transition areas between biomes have the highest probability of occurrence of genera and families. Our results indicate significant gaps in the knowledge, making it necessary to expand inventories and ecological studies in areas still unsampled.

Post-salt magmatism in the Campos Basin, offshore SE Brazil: style, distribution, and relationship to salt tectonics

Substantial magmatism occurred during the development of the marginal basins of the central and southern South Atlantic. Situated on the Brazilian side of the central segment, the Campos and Santos basin represent a transitional margin, located between the magma-rich margin in the north and the magma-poor margin in the south. In addition to magmatism associated with the initiation of continental rifting, the southeast Brazilian basins experienced three main magmatic events; one during the early post-rift (i.e., sag stage) and two during the late post-rift (i.e., passive margin stage), both occurring after deposition of a thick, late Aptian salt layer. The products of post-salt, intrusive and extrusive magmatism in the southern Campos Basin are imaged in seismic reflection data and have been directly penetrated by boreholes, yet they remain poorly understood in terms of their style, detailed geometry, and distribution. Furthermore, the temporal, spatial and possibly genetic relationships between these post-salt igneous products and salt-tectonics are largely unknown. Documenting these possible salt-magma interactions is important to understanding the tectono-stratigraphic evolution of Campos Basin and other salt-bearing passive margin basins subject to magmatic activity. We use 2D and 3D seismic reflection and borehole data from the southeastern Campos Basin, offshore Brazil to map and characterize post-salt igneous sills and volcanoes, and to understand the interaction between salt tectonics and igneous products. We identified 99 sills emplaced within uppermost Aptian-to-Maastrichtian strata, 83 emplaced above the salt and 16 intra-salt, and 15 volcanoes within Upper Cretaceous-to-lower Paleogene strata, associated with a >310 km2 lava field. We also identify four, subsalt-sourced, vent-like structures, which vary in age from Paleogene to Late Cretaceous. Salt and overburden structures define a domain of extensional deformation on a base-salt basement high, and a domain of contractional deformation in the adjacent basement low. The relationship between igneous intrusions and salt tectonics is complex, i.e., in areas where they are common, sills appear to have locally restricted salt flow and the growth of large salt structures, whereas in other cases, salt structures and overlying faults appear to have partially acted as pathways to intruding magma, allowing it to ascend to relatively shallow depths. Extrusive igneous products exclusively developed after the main phase of salt movement. However, salt distribution influenced the location of volcanoes, given the latter developed where salt is welded or very thin. Salt flow and thickness also controlled the distribution of lava flow products, which accumulated in structural lows between large salt tectonic structures. Our work indicates a complex relationship between salt tectonics and magmatic emplacement that impact the post-rift evolution of Campos Basin.

Water quality decreased by urbanisation and Pinus based silviculture in Southern Brazil

ABSTRACT Changes in land use and land cover (LULC) can largely decrease water quality across spatial scales. Watercourse degradation is caused mainly by urbanization, however other activities such as agriculture can also negatively affect the water quality. Regional characteristics may produce specific responses to different changes in the river basin, but there is few information from some regions and landscapes (e.g. Pinus silviculture). Here we compared two river basins in southern Brazil: Antas River subbasin (urban) and Faxinalzinho Stream Basin (agricultural). LULC was evaluated in the basin and at three sample points—at 450 m proximity buffers. We collected aquatic macroinvertebrates (AMI) and identified them at the family and genus levels to calculate biotic indices. LULC and AMI data were associated with the NMDS and redundancy analyzes. We observed high percentage of vegetation in both basins, with predominance of urban + rural areas in the Antas River and mostly rural area in Faxinalzinho Stream. Biotic indices showed good water quality in the rural watercourse, NMDS and RDA associated resistant taxa with urbanization, showing the sufficiency of family-level identification for water quality assessment. Despite presenting good conditions, the Pinus associated stream requires proper management to maintain its quality, and the urban river urgently requires recovery endeavours.

Land Use Changes in the Teles Pires River Basin’s Amazon and Cerrado Biomes, Brazil, 1986–2020

The Teles Pires River basin in Brazil’s center-west has recently expanded agricultural economic development at the expense of both the Amazon rainforest and Cerrado savannah. We evaluated these changes occurring in this basin over the last 34 years. Maps were generated to determine changes in land use classifications between 1986, 1991, 1996, 2000, 2005, 2011, 2015, and 2020. The supervised classification of Landsat 5 and 8 images used the maximum likelihood algorithm. Satellite spatial data on land use downloaded from the United States Geological Survey were validated according to 1477 locations, where our research team categorized land use in the field during 2020. The growth in agricultural crops (+643%) and pasture (+250%) from 1986 to 2020 were detrimental to natural areas, such as the rainforest and savannah. The percentage increase in the agricultural areas between the evaluated years peaked around 1996 and stabilized in 2020 at 40% of the Teles Pires River basin’s land area. Land use change patterns were related to political/economic events in Brazil, forest/pasture conversions until 2011, and the change from pasture to crops from 2011 to 2020. There was greater intensity in the changes in the upper Teles Pires River basin toward the south, which expanded northward over time. Sustainable agricultural intensification is needed in such stabilized, frontier areas.

Population biology of the freshwater crab Dilocarcinus pagei Stimpson, 1861 (Decapoda: Trichodactylidae) in the Araguari River, south-eastern Brazil

ABSTRACT Dilocarcinus pagei is a freshwater crab that has a wide distribution in South America, occurring in the main river basins of Brazil. Our study analysed some aspects of the population biology of D. pagei in a population that occurs in the Araguari River, in south-eastern Brazil. Crabs were sampled between September 2020 and November 2021. The population structure was analysed according to the organisms’ size, sex and life stage. The frequency of demographic groups (adults and juveniles) over months was assessed using an environmental gradient analysis and a canonical correspondence analysis (CCA). A total of 392 crabs were collected, 282 males and 110 females. Male crabs were more abundant during most of the sampling period. Thus, the sex ratio in general and for most months was biased towards males. Gradient and CCA analyses showed seasonality in the occurrence of ovigerous females. This demographic group was more frequently sampled when the local rainfall increased. Our study provides relevant information about the population and reproductive biology of D. pagei, which may contribute to the understanding of the reproductive traits of freshwater crabs and also the ecological role of this species in the environments it inhabits.

Water quality assessment and hydrogeochemistry of a sedimentary basin in a semi-arid area under increasing exploitation: Insights from multivariate statistical analyses, GIS, and modeling

The Paleozoic to Cretaceous sedimentary multi-layered aquifer systems of the sag-Jatobá Basin in semi-arid northeastern Brazil have been studied for quality assessment and screening of the factors controlling the groundwater chemistry evolution. Groundwater samples at 151 sites, maximum depth of 730 m, coupled with hydrological data characterizing the hydro-geological units were used to perform ionic ratios, GIS maps, modeling, and multivariate statistical analyses. The integrated statistical, GIS, and graphical techniques have shown the presence of five groups (i.e., C1 to C5), which increase salinity along the flowpath. C1 to C3 are mainly related to preferential recharge areas under unconfined conditions. The majority of these samples are Na+–HCO3− to Na+–Cl−. C4 samples are more evolved Na+–Cl− to Na+–mixed water roughly following flow path, likely related to areas of an aquifer system under semi-confined conditions. C5 samples have the highest TDS values with a typical Na+–Cl− groundwater type which coupled with the identified lithology reveals a greater degree of confinement. Groundwater chemistry evolution is controlled by climatic, geogenic, hydrologic, and anthropogenic factors mainly governed by evapotranspiration with subsequent cyclic salts dissolution and rock weathering in conjunction with the ion exchange, mixing with saline water, and nitrate contamination. The physical-chemical parameters of ∼85% of groundwater samples are within the World Health Organization (WHO) guidelines for drinking purposes. Conversely, irrigation ion-based indices such as salinity, Kelley Ratio, and Permeability Index showed that most groundwater is not suitable for irrigation if left untreated. The hydrogeochemical investigation contributed to the characterization and understanding of the flow and long-term geochemical evolution of the complex multi-layered aquifer systems of the Jatobá Basin. In this research, some guidelines are being proposed to be followed that may lead to a saving in global water resources while maximizing food production in similar arid to semi-arid areas.

The Cretaceous of the Cameroon Atlantic Basin (Central Africa): sediment provenance, correlation, paleoenvironment and paleogeographic evolution of the Eastern Proto-Atlantic margin (Central Gondwana)

An integration of geochemistry, mineralogical and palynological data is used to depict the sediment provenance and distribution, the sedimentary environment and the paleogeographic evolution of the Cretaceous Atlantic Basin of Cameroon. The basin is located along the African western coast, in the heart of the Guinea Gulf, and includes the Campo, Douala, and Rio-del-Rey sub-basins from South to North. The sediments of the Campo sub-basin are derived from rocks of intermediate composition, those of the Douala sub-basin from intermediate to mafic rocks in the southern and felsic rocks in the northern parts, and those of the Rio-del-Rey sub-basin from felsic rocks with a contribution of rocks of intermediate composition. The paleoweathering index and Index of Chemical Variability values for Campo, Douala and Rio-del-Rey sub-basins range from 71.26 to 76.88 and 0.98 to 2.12, 67.15 to 99.39 and 0.37 to 0.90, and 73.17 to 92.90 and 0.44 to 10.03, respectively, indicating sub-maturity, high maturity and sub- to high maturity deposits. Al2O3 vs. V and Al2O3 vs. P2O5 plots, and palynologic data such as marine (e.g. dinoflagellates and microforaminifera) and continental (e.g. Classopollis sp., Ephedripites sp., Botryococcus sp.) species suggest a deposition in more or less deep lacustrine (Campo sub-basin), fluvio-deltaic to shallow marine (Douala sub-basin), and marginal to shallow marine (Rio-del-Rey sub-basin) environments. The paleoweathering index values, the clay minerals (kaolinite, illite and chlorite/vermiculite) distributions, and the palynological data point to arid to semi-arid climate in the Campo sub-basin and semi-arid to periodically humid conditions in the Douala and Rio-del-Rey sub-basins. The tectonic setting diagram suggests collision tectonic events that are inconsistent with the classic geological history of the Atlantic Basin. The situation is in fact related to Precambrian events that affected the basement rocks from which the studied sediments were derived, and probably to the compressional tectonics during the evolution of the South Atlantic Ocean. Although these sub-basins share the same geological history, there are some differences, such as the degree of sediment maturity, the diagenetic effects, the lithology of rock sources, the paleoenvironments of deposition and their fluctuation, depending on the moment the tectonic of Atlantic opening reached them (northward progression of the W-E extension) and the northern shearing along the southern area of the Benue through axis (Rio-del-Rey). The geological history of the Cameroon Atlantic Basin is similar to those of Gabonese and Nigerian basins, along the African western coast, and of those of the Brazilian basins along the eastern coast (Santos Basin to Pernambuco-Paraiba Basin).

Brazilian basins characterization based on the distributions of elements in desalted crude oils using classical multivariate analysis and kohonen self-organizing map

The classification of petroleum regarding origin is usually carried out by Ni, V, and S correlations because these elements are essentially present in the oil phase. In contrast, other elements can be partitioned with the water phase. In this work, extraction of the water-soluble elements was performed on 70 crude oil samples from six Brazilian Basins. Both original and washed oils were analyzed for their metal concentrations by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted acid decomposition of the matrix. Then, Spearman's correlation between the original and washed oils showed element partitioning. The association of elements in the washed oils was used to avoid repetitive information by reducing the number of variables. Principal components analysis, which is a commonly employed multivariate technique, was applied to the reduced matrix, but Basin's separation was not possible because of the poor contribution (50%) of PC1 and PC2 to the variance. Then, the Kohonen self-organizing map (KSOM) artificial neural network was performed on the same matrix, with a 5x5 hexagonal topology based on Euclidean distance, resulting in a more robust analysis. The proposed data treatment allowed the association of Mo, Re, and V with marine anoxic origin, while Co, Ni, and Ce concentrations increased in petroleum from terrestrial oxic origin, and Basins were separated regarding the occurrence of these elements. Other metals such as Cu, Fe, Mn, and Zn were not significant for the classification of Basins possibly due to other geochemical processes such as the formation and oxidation of sulfides.

Uplifting mountains and shaking deserts: volcano-tectonic earthquakes revealed by soft-sediment-deformation structures in Upper Cretaceous aeolian deposits

ABSTRACT During the last stages of Gondwana fragmentation, large regions of the newly formed South American continent were covered by extensive deserts. Some parts of this continental landmass were synchronously affected by pronounced tectonism and magmatism, which were responsible for reshaping the regional topography. In this context, the southwestern part of the Sanfranciscana Basin in central Brazil is a key area for understanding this particular period in the geodynamic evolution of the South American continent. Aeolian deposits of the Posse Formation in the basin occur in direct association with volcanic rocks of the Upper Cretaceous Mata da Corda Group. Here, we report evidence of synsedimentary magmatism in direct association with soft-sediment-deformation structures, including flame structures, load casts and pseudonodules, water-escape structures, convolute lamination, faults, breccias, and clastic dikes, developed exclusively in aeolian sandstone and siltstone facies. The deformation features are interpreted as indicative of liquefaction, fluidization, and brittle behavior of the loose to partially lithified, wet sandy–silty sediments. The Late Cretaceous aeolian sedimentation is contemporaneous with the uplift of the Paranaíba High and associated magmatism in the Minas–Goiás Alkaline Province. In this context, these significant volcano-tectonic activities are considered to have triggered ductile to brittle deformation in the reported aeolian deposits.

Atmospheric and Oceanic Patterns Associated with Extreme Drought Events over the Paraná Hydrographic Region, Brazil

The Paraná Hydrographic Region (PHR) is one of the main hydrographic basins in Brazil, standing out for its energy generation and consumption, among other ecosystem services. Thus, it is important to identify hydrological drought events and the driest periods inside of these droughts to understand the anomalous atmospheric circulation patterns associated with them (a multiscale study). This study used the standardized precipitation index (SPI) for the 12-month scale to identify hydrological drought episodes in the PHR from 1979 to 2021. For these episodes, the severity, duration, intensity, and peak were obtained, and the SPI-6 was applied to the longest and most severe drought to identify periods with dry conditions during the wet season. Anomalous atmospheric and oceanic patterns associated with such episodes were also analyzed. The results reveal that the longest and most severe hydrological drought on the PHR started in 2016. The end of this episode was not identified by the end of the analyzed period. The SPI-6 revealed three rainy seasons during this drought event marked by anomalous dry conditions: 2016/2017, 2019/2020, and 2020/2021. In general, the circulation patterns identified differ in each period, for example, in 2016/2017, an El Niño event was dominant, in 2019/2020, the tropical Pacific Ocean showed neutral conditions, and in 2020/2021, a La Niña episode was registered. Despite that, in the three periods, the anomalous atmospheric patterns contributed to the weakening of the low-level jet east of the Andes and, consequently, to the decreasing of the moisture transport to the PHR, then leading to dry conditions over the basin.

DNA extracted from museum specimens of the 19th century provides a taxonomic resolution on the identity of the characid fish Psalidodon jequitinhonhae (Ostariophysi: Characiformes)

Abstract Psalidodon jequitinhonhae was originally proposed as a variety of Tetragonopterus rutilus, based on the analysis of 14 specimens from the Jequitinhonha River, Brazil. In 1910 it was relocated in Astyanax, as A. fasciatus jequitinhonhae in Tetragonopterinae and in 2020 in Psalidodon, as Stethaprioninae member. However, in none of these revisions, P. jequitinhonhae was morphologically redescribed. A short sequence of the Cytochrome c oxidase subunit I (COI) gene obtained from one of the syntypes is compared to sequences obtained from new samples, allowing the recognition of the species and its morphological redescription based on new specimens. Both morphological and molecular data converged and corroborated P. jequitinhonhae as a valid species, occurring in the Jequitinhonha and Pardo river basins in Brazil. The syntype that provided the analyzed COI sequence is referred to as the lectotype by present designation.