Resumen en Inglés:

Abstract We combined detailed field work with whole-rock geochemistry of samples from both surface exposures and rock chips from a ~300 m pile of basalt retrieved from a groundwater borehole in the Jaú region (central part of the state of São Paulo) to contribute to the stratigraphic knowledge of the northern Paraná Magmatic Province. The P2O5 content was used as the first guide to flow identification, always combined with other minor and trace elements (mostly Ti, Zr, Sr, and Cu). This approach allowed the establishment of a stratigraphic column with 16 flows, which were tentatively divided into three sequences. Regional correlations show that the lower portion of these basalt flows (Sequence 1) has good correspondence with the flow-by-flow succession identified at the border of the Paraná Basin by previous regional works. The upper eight flows, occurring at the top of the plateau where the thickness of basalt reaches up to 300 m, should have their continuity westward (toward the center of the Paraná Basin), where the volcanic pile thickens. The local preservation of these upper flows may result from significant (up to 170 m) displacements along the ENE-directed Jaú fault, identified from stratigraphic relations here defined in the basalt pile.

Resumen en Inglés:

Abstract In the Carajás Province, many Au and Cu deposits are hosted in Archean metabasic rocks belonging to the Itacaiúnas Supergroup. These metabasic rocks underwent seawater metamorphism of greenschist facies concomitantly to the volcanic activity and banded iron deposition. In the Carajás Province, synkinematic granite magmatism occurred at ca. 2.75 Ga as represented by the Estrela, Serra do Rabo, Planalto, and Igarapé Gelado granites. Emplacement at relatively shallow levels created thermal aureoles of albite-epidote hornfels to hornblende hornfels facies. Metabasic xenoliths show assemblages of hornblende hornfels. Regional stresses and lateral expansion of the syntectonic granites promoted high-temperature low-pressure metamorphism and ductile deformation in the host metabasic rocks. Dehydration reactions increased the fluid pressure permitting hydraulic fracturing and veining in the metabasaltic rocks. These conditions increased the kinetic energy of minerals so that pressure solution and dissolution of minerals were enhanced. The material transfer caused by the advective flow of supersaturated fluids leads to the formation of amphibole-bearing veins and subordinate quartz-bearing and plagioclase-bearing veins. Progressive reactions during thermal metamorphism promoted the replacement of actinolite to ferropargasite/edenite and Na-plagioclase to Ca-plagioclase. Silica produced in these reactions was transported by fluids and deposited in veins that crosscut the amphibolites.

Resumen en Inglés:

Abstract In February 2023, anomalously heavy rainfall caused widespread landslides in the coastal city of São Sebastião (Southeastern Brazil). This report describes the first version of a landslide inventory dataset for this event. The inventory is primarily based on the analysis of aerial images with 10 cm spatial resolution acquired immediately after the event, as well as archive images from Google Earth and PlanetScope. Delimitation of the landslides relied on a comparison of the images along with the area’s Digital Surface Model (DSM) and hydrography. The spatial vector dataset (shapefile and geopackage) contains points representing the landslide’s crowns and polygons indicating the affected area and is openly available in Zenodo.

Resumen en Inglés:

Abstract Net erosion recorded in lithological columns of hundreds of wells from the proximal domain of the Sergipe–Alagoas Basin was quantified through palaeoburial indicators: transit time sonic logs (DT) and vitrinite reflectance profiles (VRe). The preferred determinations with DT logs of pelitic rocks compound a large database and are less subject to variations in sampling and laboratory procedures. The sonic log profiles of 485 wells have been used for the calculation of the net erosion grid, while just 60 VRe profiles have been used for this purpose. Net erosion varies typically from 100 to 700 m in the Sergipe Sub-basin to the south, probably as a result of isostatic compensation to the sedimentary loads of the post-rift stratigraphic sequences. The Alagoas Sub-basin to the north stands as the most eroded. The average net erosion in the Alagoas SB is around 750 m but reaches more than 1,200 m in the north. The main cause of the erosion of the syn-rift strata in the Alagoas SB is probably the long-time sub-aerial exposure of uplifted rift flanks. Late Albian tectonic inversion, focused on northern Alagoas SB, enhanced erosion as evidenced in seismic sections, especially those parallel to the coast.

Resumen en Inglés:

Abstract Conulariids are extinct scyphozoans, have benthic and sessile life modes, and inhabited shallow marine platforms. Taphonomic studies of these animals from the Parnaíba Basin are scarce, distinctly from the Paraná Basin. The present work seeks to analyze the taphonomic characteristics of Conularia quichua from the Pimenteira Formation, Parnaíba Basin, and infer deposition events that influenced this fossiliferous concentration. The material is housed at Laboratório de Paleontologia de Macroinvertebrados (LAPALMA) and consists of 43 specimens. The taphonomic signatures used in the analyses were orientation in relation to the bedding plane, concentration, degree of preservation, and theca filling. The cluster and correspondence analyses evidenced two taphonomic classes for single-unit, fragile skeletons of conulariids from Pimenteira Formation: the taphonomic class 1 comprehends obliquely, filled, and complete skeletons; the taphonomic class 2 comprehends concordantly, fragmented, flattened, grouped, and isolated skeletons. A high-stand system tract, after the maximum transgressive surface of the Pimenteira Formation, is interpreted to be the depositional environment of this concentration, where an episodic high-energy event was responsible for the fossiliferous lens. In addition, the lack of preserved calcium carbonate shells suggests acidic conditions, assuming that diagenetic control occurred in this accumulation.

Resumen en Inglés:

Abstract The Mingo’o locality belongs to the Nyong Complex, located on the northern edge of the Congo Craton. In order to estimate the depth parameter of iron mineralization, outcrop studies, and ground magnetic geophysical surveys have been conducted. The petrographic analysis of outcrops reveals that Mingo’o’s banded iron formations comprise quartz–hematite BIFs (QHB) and quartz–magnetite BIFs (QMB). Also, the rocks are magnetic, with well-expressed millimetric dark bands of magnetite and hematite alternating with light bands of quartz. Magnetite and hematite crystals ranged in size from 0.1 to 3 mm, while quartz crystals were between 0.1 and 2 mm. The use of a ground magnetic survey reveals the presence of BIFs highlighted by total magnetic intensity, reduction to the equator, and total gradient, with values of 524.9–8,866.7 nT, -1,464.9 to -41.8 nT, and 36.781–86.470 nT/m, respectively. The 3D modeling shows that magnetic susceptibility values ranging between 0.6 and 3 SI are associated with BIFs. This model shows that the iron mineralization body extends 800 m N-S and 1,000 m E-W, with depth > 500 m, which is also confirmed by the Euler deconvolution method. The correlation of all these results shows a high BIF occurence in the elevated zone (> 400 m). This is a similar hypothesis to some of the previous surveys executed on the northern edge of the Congo Craton.

Resumen en Inglés:

Abstract The Uruguayan onshore portion of the Pelotas Basin is the Laguna Merin Basin. Despite its interesting geological and geophysical features, such as the highest Bouguer gravity anomaly and the youngest volcanic calderas in the country, it is the least known basin in Uruguay. In this study, a stratigraphic chart is presented for the first time, and an integrated analysis of its sedimentary infill is performed through the acquisition of horizontal-to-vertical spectral ratio data as well as geological and geophysical data available from previous studies. The Cretaceous sedimentary infill was restricted to the rift phase, corresponding to alluvial and fluvial deposits. The Cenozoic sedimentary cover corresponds to continental to marine sedimentary rocks and sediments deposited from the Oligocene to the present day in a drift tectonic framework. It presents a regional areal extension that exceeds the structural rifting borders of the basin. The maximum Cretaceous/Cenozoic sedimentary infill thickness is ~500 m. Cretaceous sedimentary units related to the rift and Oligocene drift phases are only present in the Uruguayan portion of the onshore Pelotas Basin, and the thickness of the Cenozoic drift deposits (from the Miocene to modern deposits) in the Brazilian region is at least twice that in the Uruguayan region.

Resumen en Inglés:

Abstract The Neoproterozoic Dom Feliciano Belt, the southern portion of the Mantiqueira Province, has over half of its area composed of granitic rocks, forming a granitic belt from Uruguay to the southern region of Brazil. The continuum of the batholith is interrupted by the Phanerozoic cover of the Paraná Basin. The Florianópolis Batholith is composed of granitic suites that crystallized between 640 and 580 Ma, with its northern limit defined by the Major Gercino Shear Zone. The batholith crops out about 15 km west of the current border of the Paraná Basin, along a valley sculpted by the Adaga and Lessa rivers. The importance of this region lies in the limited information about the continuity of the batholith beneath the sedimentary cover. This work aims to characterize field and petrographic features and crystallization age using U-Pb laser ablation-inductively coupled plasma mass spectrometry methodology on zircon and titanite of granitoid rocks that crop out in the Picadas region. These rocks are coarse to medium-fine-grained monzogranites, porphyritic to equigranular, with biotite and hornblende as the mafic phases. The U-Pb results showed the existence of Paleo, Meso, and Neoproterozoic (Tonian) inheritances and crystallization events at ca. 630–624 Ma and at 598 Ma.

Resumen en Inglés:

Abstract The definition of geological domains is critical for mineral exploration and has been enhanced through the development of three-dimensional (3D) models. This study focuses on the marble ore bodies in the Canta-Galo Marble District, located in Acarape, Ceará, Brazil, and owned by Geolux Company. Geologically, the Geolux Marble Mine lies within the Borborema Province, specifically in the Northern Domain of the Central Ceará Subdomain. The 3D model was developed using lithostructural mapping, drill hole descriptions and sampling, and an analysis of ore production and mining processes. Data were compiled into a geological database and modeled using the Leapfrog Geo® software. Geolux extracts dolomitic marble, which is then transported to external companies for processing. This manuscript presents a geological model of the marble deposit, based on historical drill holes and geological mapping of the Canta-Galo District. The 3D geochemical and geological interpretation of drill holes reveals the distribution of MgO and SiO2 contents in pure and impure dolomitic marbles. Estimating marble resources will be crucial for medium- to long-term mine planning in this important district of Ceará State.