Journal of South American Earth Sciences最新文献

{"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}

{"title":"Rainfall variability, land use and land cover dynamics, and implications for climate risk through a theoretical-conceptual model for the Eastern Northeast of Brazil","authors":"Micejane da Silva Costa ,&nbsp;José Francisco de Oliveira Júnior ,&nbsp;Bárbara Godoy de Barros ,&nbsp;Luís Felipe Francisco Ferreira da Silva ,&nbsp;Kelvy Rosalvo Alencar Cardoso ,&nbsp;Akza Hellen dos Santos Silva ,&nbsp;Ana Carla do Santos Gomes ,&nbsp;Maytê Duarte Leal Coutinho ,&nbsp;Edson de Oliveira Souza ,&nbsp;Michelyne Duarte Coutinho de Morais ,&nbsp;Ninu Krishnan Modon Valappil ,&nbsp;Vijith Hamza ,&nbsp;Sudhir Kumar Singh ,&nbsp;Punyawi Jamjareegulgarn ,&nbsp;Munawar Shah","doi":"10.1016/j.jsames.2025.105470","DOIUrl":"10.1016/j.jsames.2025.105470","url":null,"abstract":"<div><div>The study assessed the variability of rainfall, land use and land cover (LULC), the influence of meteorological systems and their interactions, followed by the increase in climate risks in Maceió – Alagoas – ENEB. Monthly rainfall data were obtained from the 64-year historical series (1958–2022) of the TerraClimate platform. The TerraClimate precipitation data were validated ANA and SEMARH data, resulting in R² = 0.72 and r = 0.85. Spatially, the highest rainfall accumulations occurred from April to July (rainy season), with May and June being the wettest months (&gt;800 mm). In contrast, the months from October to February (dry season) and March, August, and September (transition season) recorded lower rainfall, with November and December being the driest months (150–201 mm). The seasonal occurrence of rainfall and the relief in Maceió were associated with areas of climate risk. Maceió is a region vulnerable to extreme rainfall events due to its geographical location, the influence of the Atlantic Ocean and the Mundaú/Manguaba Lagoons, and the interaction with multi-scale meteorological systems. With LULC, there was an expansion of forest areas in rural areas and a reduction of agricultural areas, followed by increased urbanization in neighborhoods in the western part of the city (coastal plateau). The theoretical-conceptual model of climate risk provides essential information for planning and supports decision-making for public policies. The ability to assess the impacts of extreme rainfall underscores the importance of adaptive responses by local communities through the management of public policies and strategies for adapting to climate risk.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"158 ","pages":"Article 105470"},"PeriodicalIF":1.7,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682820","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":"Geochemical analysis of lateritic duricrust formation in the Cuesta and Paulista Peripheral Depression sectors of São Paulo State, southeastern Brazil","authors":"Everton Tiago Sulato ,&nbsp;Karen Luko-Sulato ,&nbsp;Daniel Godoy ,&nbsp;Reiner Neumann ,&nbsp;Vania Rosolen","doi":"10.1016/j.jsames.2025.105473","DOIUrl":"10.1016/j.jsames.2025.105473","url":null,"abstract":"<div><div>This study aims to investigate rare earth elements (REE), U, Th, Pb concentrations, and Pb isotopic ratios in lateritic weathering profiles from the Cuesta and Paulista Peripheral Depression, Brazil. Sample analysis provided geochemical and mineralogical indicators of element mobilization and distribution, enhancing the understanding of weathering processes and parental inheritance in lateritic profiles. The lateritic duricrusts are composed of goethite, hematite, kaolinite, quartz, and rare magnetite, with a significant loss of basic cation, indicating intense weathering and leaching. However, weathering fronts show limited advancement toward intense laterization, likely controlled by climate, topography, parent rock composition, and drainage. A mineralogical trend distinguishes lateritic duricrusts by elevation, with hematite predominating at mid-to-high (Cuesta) and goethite predominating at low-to-mid (Peripheral Depression) elevations. REE concentrations correlate more with mineralogy than parent rock composition, with lower REE levels in hematite-rich lateritic duricrusts at higher elevations and higher REE content in goethite-rich ones from all elevations, influenced by the alteration stage of goethite-rich lateritic duricrusts. Light REE enrichment over heavy REE is observed in lateritic duricrusts, soils, and parent rock, with soils showing greater mobility and differential accumulation. Pb redistribution occurs during weathering, with lateritic duricrusts retaining intermediate isotopic signatures and soils exhibiting the most radiogenic Pb, while ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb ratios suggest parental inheritance among all matrices. Higher elevation lateritic duricrusts exhibit an inverse relationship between U and Pb or Th, likely driven by mineralogical stabilization, selective adsorption, and the radioactive decay of U and Th into Pb over time.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105473"},"PeriodicalIF":1.7,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577557","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":"Sediment provenance signatures of the largest river in the Andes (Marañón River, Peru): Implications for signal propagation in the Amazon drainage system","authors":"Lily J. Jackson ,&nbsp;Brian K. Horton","doi":"10.1016/j.jsames.2025.105471","DOIUrl":"10.1016/j.jsames.2025.105471","url":null,"abstract":"<div><div>The transcontinental Amazon River system carries vast amounts of sediment from the Andes Mountains and South American craton to the Atlantic Ocean. However, diagnostic provenance signatures for Andean headwater rivers and Amazonian lowland tributaries remain poorly defined. The Marañón River, the longest Andean river with the largest upland drainage area, is proposed here to be the principal tributary and contributor of orogenic sediment to the modern Amazon River. The intermontane Marañón River flows axially (longitudinally) northward for ∼550 km from 10° to 5°S in the high-relief hinterland region between the flanking 3000–6000 m high Western Cordillera and Eastern Cordillera in the Andes of Peru. Detrital zircon U-Pb ages from 18 samples (1922 analyses) of modern river sands collected at 235–3120 m altitude reveal the provenance signatures for the major sediment sources within the Marañón River drainage system. Detrital zircon U-Pb age distributions from the mainstem river and selected tributary watersheds (∼280–6600 km²) exhibit a large proportion of Precambrian to early Paleozoic grains, including prominent 1600–1400 Ma (Rondonia-San Ignacio), 1300–900 Ma (Sunsás), and 700–450 Ma (Brasiliano-Famatinian) age groups, with subordinate Permian-Triassic (300–200 Ma) and Cenozoic (66–0 Ma) ages. The detrital zircon age distributions can be linked to extensive outcrops of late Neoproterozoic-early Paleozoic metamorphic basement, Mesozoic sedimentary rocks, and Cenozoic sedimentary and volcanic deposits in the Andean fold-thrust belt. Limited variations in detrital signatures along the mainstem Marañón River match the uninterrupted exposures of chiefly pre-Cenozoic units along the length of the Western and Eastern Cordilleras. However, a greater downstream proportion of Cenozoic ages corresponds to expanded Cenozoic deposits in tributary catchments of northernmost Peru. For one tributary (Crisnejas River), we present zircon U-Pb ages from 9 bedrock source samples (866 analyses) to assess the degree to which river sand age distributions reflect the bedrock units exposed in the corresponding drainage area. A remarkable agreement between observed and predicted age distributions from sediment provenance unmixing models suggests that modern river sands faithfully preserve the relative proportions of contributing rock units. Further comparisons of U-Pb age signatures for the intermontane Marañón River with other Andean tributaries and downstream lowland segments of the Amazon River (7603 analyses of 67 samples) reveal striking similarities between Marañón and Amazon results, with many shared characteristic age components, suggesting that Amazon River provenance may be determined principally by Andean headwater tributaries such as the Marañón River.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105471"},"PeriodicalIF":1.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592544","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":"Landslide processes related to recurrent explosive eruptions in the Southern Andes of Chile (39° S)","authors":"Daniel Vásquez-Antipán ,&nbsp;Ivo Fustos-Toribio ,&nbsp;José Riffo-López ,&nbsp;Ana Cortez-Díaz ,&nbsp;Álvaro Bravo ,&nbsp;Pablo Moreno-Yaeger","doi":"10.1016/j.jsames.2025.105469","DOIUrl":"10.1016/j.jsames.2025.105469","url":null,"abstract":"<div><div>Landslides are one of the most hazardous geological processes due to their difficult-to-predict nature and destructive effects, often leading to significant loss of life, infrastructure damage, and environmental disruption. In the Southern Andes of Chile, landslides are particularly frequent and destructive due to a combination of factors, including high seismic activity, steep topography, and the presence of weak, unconsolidated pyroclastic soils. Unfortunately, the geomechanical control of landslide initiation in the Southern Andes is still poorly understood, creating a significant source of uncertainty in developing accurate landslide susceptibility or risk models. This study evaluates the geological and geotechnical factors that control the generation of landslides in pyroclastic soils using in situ data, laboratory analysis and remote sensing approaches. The study area covers the surroundings of the Mocho-Choshuenco Volcanic Complex (MCVC), one of the most explosive volcanoes in the Southern Andes. The results show that the landslides are placed on slopes covered by multiple explosive eruptions that include a period of more than 12 ka. Landslide activity is related to pyroclastic soils with significant weathering and halloysite content. In addition, the geotechnical characteristics show very light soils, with high-water retention capacity, which is vital to induce mechanical instability. The detected deformation may be associated with seasonal precipitation that would increase the pore water pressure and reduce the shear strength of the soil, promoting slow-moving landslides. The geological and geotechnical characteristics of the soils suggests that slow-moving landslides would be extended to a large part of the Southern Andes. Finally, this study contributes to improving hazard assessment to mitigate the impact of landslides on the population, infrastructures and natural resources in the Southern Andes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105469"},"PeriodicalIF":1.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577556","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":"Automated detection of landslide using synergizing dual Graph Convolutional Networks, googlenet, and machine learning techniques","authors":"Anuradha B ,&nbsp;Hadeel Alsolai ,&nbsp;Randa Allafi ,&nbsp;Munya A. Arasi","doi":"10.1016/j.jsames.2025.105457","DOIUrl":"10.1016/j.jsames.2025.105457","url":null,"abstract":"<div><div>This study explores a synergistic approach to automated landslide detection in Centro Fluminense, leveraging advanced deep learning and machine learning frameworks. The proposed methodology integrates dual Graph Convolutional Networks (DGCN) with GoogLeNet to analyze topographic and 175 pre-historic landslide data for precise mapping. A curated dataset of landslide and 195 topographic images underscores the novelty and effectiveness of this approach. The framework employs dual Graph Convolutional Networks to capture spatial dependencies and GoogLeNet to extract deep spatial features effectively. A machine learning model complements these networks to refine predictions through iterative learning processes. The study evaluates network modelling through DGCN and GoogLeNet, focusing on training and validation accuracy. Training datasets demonstrated consistent improvement in classification accuracy, increasing from 66% to 93%, while validation datasets achieved high precision, with values rising from 78% to 99%. The results emphasize the model's robustness and scalability in addressing spatial heterogeneity and complex topographic conditions. Performance metrics were rigorously analyzed, indicating a significant alignment with ground-truth data, as evidenced by a coefficient of determination (R²) of 0.92 and a mean absolute error (MAE) of 4%. The integration of DGCN and GoogLeNet outperformed conventional methods by capturing intricate spatial and contextual features. This comprehensive framework ensures reliable and automated detection, crucial for disaster risk management in regions prone to landslides. In addition to predictive modelling, the study highlights the role of preprocessing techniques, including hillside and LULC analysis, in enhancing detection capabilities. A comparative analysis of models reveals the superiority of the dual network approach over single-framework architectures, particularly in terms of accuracy and adaptability to diverse datasets. This study provides a novel contribution to landslide mapping by combining topographical insights with advanced network architectures. The proposed framework demonstrates the potential for deployment in other regions with similar geological settings, paving the way for improved disaster preparedness and management strategies.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105457"},"PeriodicalIF":1.7,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577555","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":"Assessing sediment dynamics and erosion-deposition patterns after a dam break: Insights from the Brumadinho tailings dam failure in Brazil","authors":"Caio C.S. Mello ,&nbsp;Julian C. Eleutério","doi":"10.1016/j.jsames.2025.105472","DOIUrl":"10.1016/j.jsames.2025.105472","url":null,"abstract":"<div><div>Dam break events cause disruptive scenarios, leading to the sudden release of large volumes of water and sediment downstream, resulting in significant geomorphic changes in the floodplain. Assessing the consequences of dam break events on floodplain geomorphology, including changes in channel morphology, erosion, and deposition patterns, is an emerging research field, with perspectives of understanding the potential for landform evolution concerning sediment transport and establish benchmarks for future impact assessments and event modeling. The main objective of this research is to quantitatively assess the sediment dynamics following the Brumadinho tailing dam failure, focusing on the released sediment, the bulk retained in the Ferro Carvão stream watershed, and the tailings that reached the Paraopeba River. The methodology involved geospatial evaluation and zonal statistics to calculate bulk volumes, account for uncertainties, and compare the results with available monitoring data. The results highlighted a significant uncertainty regarding the mass sediment discharge hydrograph due to particle's geotechnical properties variability. It was estimated that about half of the sediment volume released from the dam was retained in the event-scale tailing spread area, diverging from other reported values in the literature. Zonal statistics in the floodplain revealed a predominant tendency for deposition over erosion across most of the spread area, especially in downstream areas, attributed to the geomorphological characteristics of the terrain and flow characteristics. However, erosion was more prominent in areas closest to the dam, justified by the flow velocity and stream power in these areas. Additionally, a mass balance indicates that a significant amount of sediment particles is being constantly transported in Paraopeba river, driven mainly by flow regime in rainy periods.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105472"},"PeriodicalIF":1.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628572","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":"Energy balance and evapotranspiration conditioned by deforestation of a seasonally dry tropical forest (Caatinga): A series of four water seasons","authors":"Thieres George Freire da Silva ,&nbsp;Maria Gabriela de Queiroz ,&nbsp;Sérgio Zolnier ,&nbsp;Alexandre Maniçoba da Rosa Ferraz Jardim ,&nbsp;Wilma Roberta dos Santos ,&nbsp;Magna Soelma Beserra de Moura ,&nbsp;Carlos André Alves de Souza ,&nbsp;Antonio José Steidle Neto ,&nbsp;George do Nascimento Araújo Júnior ,&nbsp;Marcelo José da Silva ,&nbsp;Kaique Renan da Silva Salvador ,&nbsp;Elania Freire da Silva ,&nbsp;Luciana Sandra Bastos de Souza","doi":"10.1016/j.jsames.2025.105474","DOIUrl":"10.1016/j.jsames.2025.105474","url":null,"abstract":"<div><div>Changes in land use affect the spatial and temporal variations of surface energy balance components and evapotranspiration in the Caatinga. We aimed to assess the partitioning of energy into latent heat flux (LE) and sensible heat flux (H), as well as actual evapotranspiration (ET), in areas of Caatinga vegetation (CAA) and a deforested area (DEFA) in the Brazilian semi-arid region from 2015 to 2018. Two micrometeorological towers were installed to obtain data during the rainy, dry and transition periods. The energy balance was obtained using the Bowen ratio, based on estimates of daily, monthly and seasonal H and LE fluxes, the latter being used to determine the ET. Higher average values of net radiation (Rn), LE, H and soil heat flux (G) were observed for the CAA landscape, while minimum values were recorded in the DEFA. Mean daily the ET in the CAA and DEFA was 2.19 and 1.97 mm, respectively. Around 23% of the received Rn was used for the LE, 70% for H and 9% for G at the site of the CAA, against 21% of the Rn for LE, 72% for H and 8% for G in the DEFA. Our results further showed that the removal of native vegetation promotes reductions in Rn, air relative humidity, ET and increases the vapour pressure deficit in the DEFA. Greater contributions were observed for H in the dry season, with LE being greater during the rainy season in the Caatinga vegetation area.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105474"},"PeriodicalIF":1.7,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601308","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":"Present-day foreland development and its relation to plate tectonics in the northern Andes","authors":"Carlos E. Macellari","doi":"10.1016/j.jsames.2025.105465","DOIUrl":"10.1016/j.jsames.2025.105465","url":null,"abstract":"<div><div>Based on analysis of topography through DEM images, geomorphology, river drainage patterns, and surface geology, the foreland basins of northwestern South America are divided into three areas that coincide with segments of boundaries between the South American, Nazca and Caribbean plates. From 2° 30′ to approximately 4°30′ N, is the southern Llanos or Uplifted foreland that is characterized by uplift and a transpressive environment. Major alluvial fans and terraces representing the wedge top depozone are present on the proximal part, and Mio-Pliocene sediments are exposed on the distal part of the foreland. This foreland is the highest (486 m at the mountain front) and has the steeper slope (0.33°) of the northern Andes. Watersheds in this area exhibit low maturity and elevated heat flow is observed. Associated to this foreland is the Cauca or Nazca Segment that has a steeply dipping slab that originates a chain of recent volcanoes to the west.</div><div>The second zone (Main Llanos foreland) is developed north of the Caldas tear zone and extends to the Rio Uribante-Apure. It coincides with a flat slab configuration (Bucaramanga Segment) and is characterized mostly by pure compression. On the foreland this generates deformation of recent terraces and current uplift in the wedge top area that is eroded in several areas. Active sedimentation in an extensive alluvial plain is taking place in the distal foreland. Here the streams are transversal to the Eastern Cordillera, feeding the longitudinal NE-SW trending Meta River. The slope has an average inclination of 0.14°, and an average elevation of 286 m at the mountain front. Watersheds display a high to intermediate maturity, but are less mature to the north, coinciding the Cocuy area of current uplift.</div><div>The northernmost zone, or Barinas Foreland, east of the Venezuelan Andes, aligns with the Caribbean Segment. Major subsidence occurred in the Middle-Upper Miocene mainly in the southern basin, migrating north in the Pliocene-Pleistocene. This resulted in a mature foreland to the south with a low regional slope lacking alluvial fans and wedge top facies. In contrast, the northern area has well-developed alluvial fans, a higher regional slope, and displays current deformation at the mountain front.</div><div>The northern South American Andes illustrates how plate configuration and the associated subduction of oceanic slabs are linked to distinct foreland morphologies. Nevertheless, other factors, such as tectonic inheritance and climatic conditions, play significant roles in determining the final configuration of a specific foreland.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105465"},"PeriodicalIF":1.7,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592545","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}