Journal of South American Earth Sciences最新文献

{"title":"U-Pb and Lu-Hf zircon analysis in orogenic basins - A case study in a hot orogen, SE Brazil","authors":"Sofia Goldbach D'Orsi ,&nbsp;Renata da Silva Schmitt ,&nbsp;Silvia Regina de Medeiros ,&nbsp;Mauro Cesar Geraldes ,&nbsp;Guilherme Gonçalves Martins","doi":"10.1016/j.jsames.2025.105499","DOIUrl":"10.1016/j.jsames.2025.105499","url":null,"abstract":"<div><div>During the convergence of the São Francisco and the Congo-Angola paleocontinents, between 600 and 500 Ma, sedimentary basins were generated and metamorphosed to paragneisses within the Ribeira Orogen, SE Brazil. The Oriental Terrane, part of this orogen, and the focus of this study, is constituted of paragneisses intruded by voluminous pre-, syn- and post-orogenic batholiths. Here, we investigate the origin of the paragneisses that crop out in the city of Rio de Janeiro. The São Fidélis Group consists mostly of cordierite-sillimanite-garnet-biotite paragneisses with minor quartzite layers at granulite facies. Peak metamorphic conditions are estimated at 850 °C and 7 kbar. Our goal is to study the provenance of the protoliths and the basin's tectonic evolution, using a combination of U-Pb and Lu-Hf methods in zircons, even though these rocks underwent metamorphism above the zircon closure temperature for the U-Pb system. Fieldwork was conducted at Niemeyer Avenue and Morro Cara de Cão. Three samples from distinct lithologies were analyzed: a cordierite-sillimanite-garnet-biotite paragneiss (kinzigite), a fine-grained biotite paragneiss, and a quartzite. All samples show similar detrital zircon populations, with predominant Neoproterozoic sources and minor Mesoproterozoic and Paleoproterozoic sources. The older populations might come from African sources, such as the Kunene Anorthosite Complex and the Eburnean magmatic units of the Angola Craton and the Cabo Frio Tectonic Domain. The main Neoproterozoic populations are 980-930 Ma, 856-838 Ma, 800-740 Ma, and 690-580 Ma. These peaks coincide with the ages of the magmatic arcs described in the Oriental Terrane, suggesting them as sources. The Neoproterozoic εHf values for the dated detrital zircons range from +5 to −18, which corroborates with magmatic arc nature of these sources. The youngest detrital zircon population (590-570 Ma) could be either interpreted as metamorphic or magmatic due to Pb-loss caused uncertainties. Therefore, we propose that the maximum age of sedimentation is a time interval of 590-570 Ma and the minimum age is about 560 Ma (age of the metamorphic rims and of the Facoidal Orthogneiss syntectonic intrusion). The short period between initiation of sedimentation and metamorphism, 590-560 Ma, suggests a syn-orogenic basin, related to an arc terrane (Oriental Terrane), either a back-arc or an intra-arc basin. This period coincides with the regional metamorphism in this hot orogen.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105499"},"PeriodicalIF":1.7,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An overview of Rhyacian continental magmatic arcs of the southeastern Guiana Shield, Amazonian Craton","authors":"Lúcia Travassos da Rosa-Costa ,&nbsp;Jean-Michel Lafon ,&nbsp;João Marinho Milhomem Neto ,&nbsp;João Alberto Evangelista Pinto","doi":"10.1016/j.jsames.2025.105504","DOIUrl":"10.1016/j.jsames.2025.105504","url":null,"abstract":"<div><div>The southeastern Guiana Shield comprises an extensive orogenic belt formed during the Rhyacian period. In its Brazilian portion (Amapá and northwestern Pará), this belt includes the Rhyacian Carecuru and Lourenço domains, which are located to the north and south of the Amapá Block, an Archean terrane that was significantly reworked during the Rhyacian orogeny. This paper provides an overview of field, petrographic, geochemical, isotopic, and geochronological data supporting the recognition of continental magmatic arcs that developed during a long-lived (∼170 Ma) evolution of the accretionary stage of the Rhyacian orogeny. In the Lourenço Domain, arc magmatism persisted from 2.26 to 2.09 Ga, while in the Carecuru Domain, it spanned from 2.19 to 2.14 Ga. The studied arc-related rocks mainly consist of calc-alkaline to high-K calc-alkaline granitoids and gneisses, most of which are metaluminous, I-type, and have high contents of large-ion lithophile elements (LILE). The Archean crustal contributions to the origin of the magmas have significantly shaped their isotopic signatures, highlighting the influence of the nearby Amapá Block. The magmatic evolution in Lourenço and Carecuru domains was marked by episodic flare-ups around 2.19–2.18 Ga and 2.14 Ga, indicating periods of intensified activity typical of continental arc systems. This dynamic evolution resembles tectonic settings with long-lived arc magmatism punctuated by episodes of increased activity. Overall, the data suggest that the Rhyacian orogeny in this part of the Amazonian Craton involved tectonic processes similar to those of modern plate tectonics, characterized by prolonged arc magmatism, episodic flare-ups, and crustal interactions, pointing to a complex tectonic environment.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"159 ","pages":"Article 105504"},"PeriodicalIF":1.7,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term influence of Miocene intermontane basin alluvial sediments capture in arid valley thalwegs morphometry in the Central Andes (∼29°S)","authors":"Germán Aguilar ,&nbsp;Katia Rossel ,&nbsp;Albert Cabré ,&nbsp;María Pía Rodríguez","doi":"10.1016/j.jsames.2025.105498","DOIUrl":"10.1016/j.jsames.2025.105498","url":null,"abstract":"<div><div>Landscape evolution models suggest that thalweg morphometry is influenced by a combination of factors, including the rate of rock uplift, the soil erodibility, the channel geometry, the sediment properties and availability, and the climate changes. Approximately 6 Ma ago, the uppermost catchment of the El Transito river (∼29°S, Central Andes) captured an intermontane basin containing thick alluvial successions dating 19 to 13 Ma. We carried out an analysis of thalweg profiles to explore morphometric changes by this intermontane basin capture. The valleys that captured this basin exhibit flat profiles, with stationary knickpoints located at the basin boundaries. We propose that the supply of alluvial gravels from the intermontane basin shielded the thalweg upstream, reducing incision, while simultaneously providing abrasive material that favored incision downstream. Our findings underscore the importance of considering the long-term influence of sedimentary deposits capture when interpreting the morphometry of arid valleys in the Central Andes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105498"},"PeriodicalIF":1.7,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of source terranes of beach sediments from the NW Gulf of Mexico, Atlantic ocean: Constraints from geochemistry and U–Pb detrital zircon geochronology","authors":"Mayank Shukla ,&nbsp;Sanjeet K. Verma ,&nbsp;John S. Armstrong-Altrin ,&nbsp;Mayla A. Ramos-Vázquez ,&nbsp;Sumit Mishra ,&nbsp;Elson P. Oliveira ,&nbsp;Eduardo González-Partida ,&nbsp;Héctor Hernández-Mendoza ,&nbsp;Vivek P. Malviya","doi":"10.1016/j.jsames.2025.105496","DOIUrl":"10.1016/j.jsames.2025.105496","url":null,"abstract":"<div><div>This study investigated mineralogy and bulk sediment geochemistry of 24 sediment samples, and U-Pb ages of 200 zircons retrieved from the Tamiahua beach, NW Gulf of Mexico. The study aims to infer the provenance and possible source terranes supplying sediments to the beach area. The XRD and SEM-EDS studies reveal that the sediments are associated with quartz, plagioclase, calcite, and microcline. The Chemical Index of Weathering (CIW'), Th/U and Ba/Sr ratios (&gt;92, 3.75, and 2.27, respectively) indicate high intensity of weathering in the source region. The major as well as trace element-based diagrams along with elemental ratios of TiO₂/Zr (∼15–35), Al₂O₃/TiO₂ (∼120–312), La/Sc (5.31–6.01), La/Co (4.27–5.64), Th/Sc (0.96–1.06), and Cr/Th (3.04–16.24) suggest that the sediments are derived from felsic rocks.</div><div>The Th/U ratios of Tamiahua zircons indicate an igneous origin. The chondrite normalized rare earth elements (REE) patterns exhibit positive Ce and negative Eu anomalies and are depleted in light rare earth elements (LREE) and enriched in heavy rare earth elements (HREE). The sediments are dominated with Proterozoic Eon (Mesoproterozoic; 1053.95–1502.36 Ma), Mesozoic Era (Jurassic; 145.42–179.19 Ma and Cretaceous; 68.84–124.45 Ma), and Cenozoic Era (Eocene; 34.08–54.21 Ma and Oligocene; 25.39–33.71 Ma) zircons indicating their derivation from heterogenous source. The Proterozoic zircons in Tamiahua beach sediments are possibly contributed by the Mesa Central Province, which contains zircons from Chiapas and Oaxacan Massif complexes as well as Granjeno schist and Tamatán group from Sierra Madre Oriental Province. Mesozoic zircons are likely contributed by multiple sources, including undifferentiated turbidites of Mesa Central and Zacatecas, Caracol, San Felipe formations and Huizachal group of Sierra Madre Oriental and from Eastern Alkaline Provinces. Similarly, the Cenozoic zircons are supplied by the felsic to intermediate volcanic rocks and granitoids from the Mesa Central Province. The sediment transport and distribution to the beach area is facilitated by the rivers and their tributaries that flow from the source terranes. The results of this study also reveal a passive margin setting for the northwestern Gulf of Mexico.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105496"},"PeriodicalIF":1.7,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143725211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identifying the reactivation of ancient shear zones in Sul-rio-grandense/Uruguayan shield (South America) using geomorphological index","authors":"Aline Cambri Fredere ,&nbsp;Mateus Rodrigues de Vargas ,&nbsp;Márcio Cardoso Jr ,&nbsp;Ariane Santos da Silveira ,&nbsp;José Manuel Marques Teixeira de Oliveira ,&nbsp;Nelson Ferreira Fernandes","doi":"10.1016/j.jsames.2025.105482","DOIUrl":"10.1016/j.jsames.2025.105482","url":null,"abstract":"<div><div>Cratonic/shield regions are usually considered tectonically quiescent. Fluvial geomorphology analysis has demonstrated that these areas may face continuous deformation. This study proposes the use of anomalous <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>s</mi><mi>n</mi></mrow></msub></math></span> values, related to fluvial geomorphology, to infer recent deformation in these cratonic/shield regions. This approach is validated by the joint integration of <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>s</mi><mi>n</mi></mrow></msub></math></span> anomalies with other geomorphological indexes such as knickpoints and <span><math><mi>χ</mi></math></span>, available uplift rates, and analysis of satellite images. Our methodology was tested in the Sul-rio-grandense/Uruguayan shield, a region formed during the Neoproterozoic, and its surrounding areas, which potentially hold evidence of neotectonism. Our findings reveal that <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>s</mi><mi>n</mi></mrow></msub></math></span> anomalies coincide with tectonic-related knickpoints and follow a preferential NE-trend in the northern of the study area. In the south, several <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>s</mi><mi>n</mi></mrow></msub></math></span> anomalies are associated with elevated <span><math><mi>χ</mi></math></span> values and extend to the Quaternary sediments. In general, the NE trend observed in our joint methodology fits well with mapped Neoproterozoic shear zones and potentially reflects ongoing deformation along these ancient shear zones. Potential causes for this neotectonism include far-field stresses associated with the Andean Orogeny and tectonic plate adjustments related to the Atlantic opening, as observed in other places along the Brazilian coast. The relationship between anomalous <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>s</mi><mi>n</mi></mrow></msub></math></span> values and other geomorphological indexes supports that our methodology could be a reliable approach for mapping neotectonism at regional scales.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105482"},"PeriodicalIF":1.7,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Jurassic fern Piazopteris from the Girón Group, Colombia: A taxonomic and paleoenvironmental evaluation","authors":"Jose Manuel Torres-Parada ,&nbsp;Johanset Orihuela ,&nbsp;Carlos Mario Alarcón Gómez ,&nbsp;Jefferson Steeven Diaz Villamizar ,&nbsp;Juan Sebastián Gómez-Coronado ,&nbsp;José Javier Márquez-Prada ,&nbsp;Jorge Andrés Lizarazo-Pabón ,&nbsp;German Patarroyo","doi":"10.1016/j.jsames.2025.105488","DOIUrl":"10.1016/j.jsames.2025.105488","url":null,"abstract":"<div><div>This study investigates a new set of fossil tree ferns from the Late Jurassic Girón Group in the Eastern Cordillera of Colombia. Located on carbonaceous mudstones from the La Honda Creek, we analyzed six specimens tentatively identified as <em>Piazopteris</em> cf. <em>branneri</em> (Matoniaceae). Using thin-section petrography, scanning electron microscopy (SEM), and carbon geochemistry, including total organic carbon (TOC) and stable carbon isotope analyses (δ¹³C_org), we characterize the sedimentological context and paleoenvironmental conditions associated with these fossil remains. The lithofacies, primarily composed of dark-gray mudstone, reveal significant organic matter accumulation and suggests a low-energy depositional environment with fair organic matter preservation, likely a swampy and humid setting. Geochemical analyses, including δ¹³C_org values are consistent with this interpretation, and suggest conditions in a tropical to subtropical climate typical of the Jurassic. These findings provide new insights into the Mesozoic paleoenvironments and flora of the circum-Caribbean region and underscores the importance of the Girón Group to develop future paleobotanical studies in Colombia.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105488"},"PeriodicalIF":1.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New postcranial remains of a non-mammaliaform cynodont from the Pinheiros-Chiniquá Sequence (Middle-Upper Triassic), Brazil","authors":"Leonardo Kerber ,&nbsp;Iasmim M. Michelotti ,&nbsp;Jhonata H.A. Martins ,&nbsp;Rodrigo T. Müller","doi":"10.1016/j.jsames.2025.105487","DOIUrl":"10.1016/j.jsames.2025.105487","url":null,"abstract":"<div><div>The Pinheiros-Chiniquá Sequence (<em>Dinodontosaurus</em> Assemblage Zone, Middle/Upper Triassic) of the Santa Maria Supersequence in Brazil is renowned for its rich fossil record of traversodontid and probainognathian cynodonts (Therapsida: Eucynodontia). However, despite this diversity, their postcranial anatomy remains poorly studied. In this study, we describe new postcranial remains assigned to an eucynodont from this sequence. The specimen includes three presacral vertebrae, the proximal region of the left humerus, the proximal region of the left ulna, right and left femora. The absence of associated cranial material limits a definitive taxonomic assignment. Nonetheless, the combination of distinct femoral characteristics—(i) femoral head positioned well above the greater trochanter, (ii) greater trochanter laterally protruding with a distal projection (forming a “hook”), (iii) slender diaphysis, and iv) lesser trochanter oriented posteromedially—suggests affinities with traversodontids. Future discoveries of cranial material associated with similar postcranial remains could provide critical insights, helping to clarify the taxonomic identification of this specimen.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105487"},"PeriodicalIF":1.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithostratigraphic analysis of the La Loma Formation and depositional model of the intermontane Cesar Sub-Basin (Colombia) during the Eocene: Exploring potential for CO2 storage","authors":"Dilan Arturo Martínez-Sánchez ,&nbsp;Sait Khurama-Velásquez ,&nbsp;Carlos Alberto Ríos-Reyes","doi":"10.1016/j.jsames.2025.105486","DOIUrl":"10.1016/j.jsames.2025.105486","url":null,"abstract":"<div><div>The Cesar-Ranchería Basin in Colombia presents significant knowledge gaps concerning its Eocene stratigraphy, impeding a comprehensive understanding of its geological evolution and regional correlations. This study focuses on characterizing the La Loma Formation (Eocene) using well log data, petrographic analysis, and X-ray diffraction to delineate its depositional environment and sediment provenance. The La Loma Formation comprises sandstones, conglomerates, and interbedded siltstones within the central La Loma syncline. Petrographic analysis of 100 thin sections identifies two distinct sedimentary environments: fluvial fans and a fluvial system. The Santander Massif and Serranía de Perijá are identified as primary source areas for La Loma Formation sediments. In the lower section of the La Loma Formation, sedimentary contributions primarily originated from the Santander Massif (Eastern Cordillera), indicating uplift during the early Eocene. This geological event potentially redirected drainage towards the Lower Magdalena Valley Basin and connected the Cesar Sub-basin with the Middle Magdalena Valley Basin. Conversely, the upper section of the La Loma Formation reveals a mixed sediment contribution from the Santander Massif, Serranía de Perijá, and Sierra Nevada de Santa Marta. This variation suggests significant environmental shifts and tectonic reconfigurations during the Eocene, influencing connectivity between the Middle Magdalena Valley Basin, the Lower Magdalena Valley Basin, and the Cesar Sub-basin. This lithostratigraphic analysis enhances our understanding of the La Loma Formation's role in regional stratigraphy and basin evolution within the Cesar-Ranchería Basin. Moreover, the study explores the formation's potential for carbon dioxide (CO₂) storage, emphasizing its geological stability, adequate porosity, and potential as a natural sealant, crucial for long-term CO₂ storage and climate change mitigation strategies.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105486"},"PeriodicalIF":1.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143724627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interpolation and artificial neural network to estimate soil spatial variability affected by land use and altitude","authors":"Fatemeh Taghipour,&nbsp;Seyed Mostafa Emadi,&nbsp;Majid Danesh,&nbsp;Mehdi Ghajar Sepanlou","doi":"10.1016/j.jsames.2025.105485","DOIUrl":"10.1016/j.jsames.2025.105485","url":null,"abstract":"<div><div>Finding the most suitable methods, which may predict soil spatial variability is essential for proper handling of agricultural lands affected by land use types and altitude. There is not much data on the use of artificial neural network (ANN) outperforming the traditional methods such as the interpolation methods for predicting soil spatial variability. Accordingly, the interpolation methods of inverse distance weighting (IDW), kriging, and co-kriging, as well as ANN were tested to predict soil spatial variability of pH, salinity (EC), and cation exchange capacity (CEC) affected by land use type (cultivated and uncultivated lands, orchard, forestry and rangeland) and altitude (-20-0 (A1), 0–100 (A2), 100–500 (A3), and &gt;500 m (A4)) in a 9545 km² research area. The chemical properties of the 249 soil samples (0–15 cm) were determined. Land use type indicated pH of 6.56 (forestry) to 7.32 (cultivated land), EC of 1.10 (forestry) to 2.87 dS/m (rangeland), and CEC of 17.71 (uncultivated land) to 37.01 meq/100 g soil (forestry). Altitude resulted in pH of 6.72 (A4) to 7.35 dS/m (A2), EC of 1.31 (A4) to 1.90 (A2) dS/m, and CEC of 20.07 (A1) to 34.45 meq/100 g soil. Although cross-validation method (using mean error (ME) and root means square error (RMSE)) indicated the accuracy of interpolation methods to predict soil spatial variability, ANN was the most suitable one. The proper training of ANN may precisely predict the spatial heterogeneity of soil chemical properties affected by land use type and altitude, useful for the appropriate handling of agricultural lands.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105485"},"PeriodicalIF":1.7,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143631977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleomagnetism of the Permian De la Cuesta formation (Narváez Range, NW Argentina): Apparent polar wander path and paleogeography of Gondwana and Pangea","authors":"Cecilia Mariel Spagnuolo ,&nbsp;Augusto Ernesto Rapalini ,&nbsp;Ricardo A. Astini ,&nbsp;Sabrina Y. Fazzito","doi":"10.1016/j.jsames.2025.105468","DOIUrl":"10.1016/j.jsames.2025.105468","url":null,"abstract":"<div><div>Permian times were characterized by distribution of land masses forming a supercontinent called Pangea. Although its existence has been accepted for many decades, there is still debate about its configuration. In order to provide new constraints on the position of Gondwana during late Paleozoic times, a paleomagnetic study was carried out on Carboniferous-Permian red beds exposed in the Famatinian Ranges, western Argentina (27°43′S 67°58′W). Eighty four oriented samples (11 sites) were submitted to standard stepwise demagnetization procedures. Magnetic analysis was complemented by acquisition of isothermal remanent magnetization (IRM), backfield curves and anisotropy of magnetic susceptibility (AMS) on selected specimens. Inclination shallowing due to compaction was evaluated by application of oriented acquisition of IRM and demagnetization experiments. The high-temperature magnetic components of sites are characterized by southward declinations with positive inclinations that yield a positive fold test. A new paleomagnetic pole is calculated and suggests an age of magnetization between 300 and 270 Ma, thatmatches with a Pangea B distribution although a Pangea A2 model can not be ruled out if the magnetization age is restricted to 280-270 Ma.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105468"},"PeriodicalIF":1.7,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143631976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}