Pub Date : 2025-11-08DOI: 10.1016/j.jsames.2025.105863
Leonel Vitório Esteves , Carlos Fabricio Assunção da Silva , José Miguel Reichert , Artur Paiva Coutinho
Coastal areas in the state of Pernambuco in northeast Brazil have numerous records of floods that have worsened over the years, thus requiring hydrological studies to enhance decision-making in water resource management. This study analyzes simulations of the Sirinhaém River Basin (SRB) floodplain, in Pernambuco, under distinct land use conditions for the years 1992, 2002, 2012, and 2022, with return periods (RP) of 20, 50, and 100 years. Additionally, a scenario including the planned Barra de Guabiraba flood-control dam was simulated to evaluate its potential effectiveness in reducing peak discharges and flood extent within the basin. Intense rainfall equations were calculated using the disaggregation method, and the Curve Number (CN) was determined using the interpolation method. Hydrological modeling was performed using the HEC-HMS software, calibrated through the Nash-Sutcliffe Efficiency (NSE) method and Percent Bias (Pbias), while hydrodynamic modeling was conducted using HEC-RAS, with digital elevation models from the three-dimensional PE3d program. Calibration involved two stream gauges: Engenho Bento with an NSE of 0.556 and Pbias of 11.78 %, and Mato Grosso with an NSE of 0.607 and Pbias of −13.73 %. Across the basin, a total of 407 residences were identified as being at risk of flooding across the five studied municipalities. Changes in land use and land cover are contributing to increased flow rates and that the river basin requires the implementation of flood control dams, as occurrences are already reported for return periods above 20 years.
{"title":"Spatiotemporal simulation and analysis of coastal floodplain in Pernambuco, northeast Brazil","authors":"Leonel Vitório Esteves , Carlos Fabricio Assunção da Silva , José Miguel Reichert , Artur Paiva Coutinho","doi":"10.1016/j.jsames.2025.105863","DOIUrl":"10.1016/j.jsames.2025.105863","url":null,"abstract":"<div><div>Coastal areas in the state of Pernambuco in northeast Brazil have numerous records of floods that have worsened over the years, thus requiring hydrological studies to enhance decision-making in water resource management. This study analyzes simulations of the Sirinhaém River Basin (SRB) floodplain, in Pernambuco, under distinct land use conditions for the years 1992, 2002, 2012, and 2022, with return periods (RP) of 20, 50, and 100 years. Additionally, a scenario including the planned Barra de Guabiraba flood-control dam was simulated to evaluate its potential effectiveness in reducing peak discharges and flood extent within the basin. Intense rainfall equations were calculated using the disaggregation method, and the Curve Number (CN) was determined using the interpolation method. Hydrological modeling was performed using the HEC-HMS software, calibrated through the Nash-Sutcliffe Efficiency (NSE) method and Percent Bias (Pbias), while hydrodynamic modeling was conducted using HEC-RAS, with digital elevation models from the three-dimensional PE3d program. Calibration involved two stream gauges: Engenho Bento with an NSE of 0.556 and Pbias of 11.78 %, and Mato Grosso with an NSE of 0.607 and Pbias of −13.73 %. Across the basin, a total of 407 residences were identified as being at risk of flooding across the five studied municipalities. Changes in land use and land cover are contributing to increased flow rates and that the river basin requires the implementation of flood control dams, as occurrences are already reported for return periods above 20 years.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105863"},"PeriodicalIF":1.5,"publicationDate":"2025-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521110","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}
Pub Date : 2025-11-07DOI: 10.1016/j.jsames.2025.105865
C. Ferreyra , B. Christofoletti , V. Penzo , G.C. Antunes , L.V. Warren , M.J. Arrouy , D.G. Poiré , L.E. Gómez-Peral
Following the development of the Piedra Amarilla Surface (PAS), where a major karstic unconformity formed during prolonged subaerial exposure, the Tandilia System underwent a profound paleoenvironmental shift in the early Ediacaran. These changes are recorded in the Colombo and Cerro Largo formations, which overlie the PAS and represent a large-scale transgressive–regressive cycle in the Sierras Bayas Group. This cycle begins with post-glacial deposits and culminates in a high-energy, storm-dominated shoreline system, marking a major reorganization of depositional environments in the basin. Sedimentological, stratigraphic, and paleocurrent analyses from eight measured sections identified twelve lithofacies, grouped into four facies associations, arranged in a coarsening-upward pattern from glacimarine deposits (FA-1) to offshore-transition deposits (FA-2), and finally to storm-wave and fair-weather-wave dominated shoreface deposits (FA-3 and FA-4, respectively). Paleocurrent data indicate a NE–SW-oriented paleoshoreline, with deeper marine areas toward the W–NW, in agreement with regional paleogeographic reconstructions. In this high-energy context, microbial mats played a key role in stabilizing substrates and preserving small-scale delicate sedimentary structures. The interpreted depositional model highlights the development of a high-energy overlaying shoreline glacimarine deposits and the dynamic interplay between storm and fair-weather wave processes in shaping early Ediacaran littoral systems.
{"title":"Storm-dominated coastal dynamics in the early Ediacaran record of Argentina","authors":"C. Ferreyra , B. Christofoletti , V. Penzo , G.C. Antunes , L.V. Warren , M.J. Arrouy , D.G. Poiré , L.E. Gómez-Peral","doi":"10.1016/j.jsames.2025.105865","DOIUrl":"10.1016/j.jsames.2025.105865","url":null,"abstract":"<div><div>Following the development of the Piedra Amarilla Surface (PAS), where a major karstic unconformity formed during prolonged subaerial exposure, the Tandilia System underwent a profound paleoenvironmental shift in the early Ediacaran. These changes are recorded in the Colombo and Cerro Largo formations, which overlie the PAS and represent a large-scale transgressive–regressive cycle in the Sierras Bayas Group. This cycle begins with post-glacial deposits and culminates in a high-energy, storm-dominated shoreline system, marking a major reorganization of depositional environments in the basin. Sedimentological, stratigraphic, and paleocurrent analyses from eight measured sections identified twelve lithofacies, grouped into four facies associations, arranged in a coarsening-upward pattern from glacimarine deposits (FA-1) to offshore-transition deposits (FA-2), and finally to storm-wave and fair-weather-wave dominated shoreface deposits (FA-3 and FA-4, respectively). Paleocurrent data indicate a NE–SW-oriented paleoshoreline, with deeper marine areas toward the W–NW, in agreement with regional paleogeographic reconstructions. In this high-energy context, microbial mats played a key role in stabilizing substrates and preserving small-scale delicate sedimentary structures. The interpreted depositional model highlights the development of a high-energy overlaying shoreline glacimarine deposits and the dynamic interplay between storm and fair-weather wave processes in shaping early Ediacaran littoral systems.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105865"},"PeriodicalIF":1.5,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521111","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}
Pub Date : 2025-11-06DOI: 10.1016/j.jsames.2025.105862
D. Legrand , M. Perton , R. Campion , L. Peiffer , C. Valdés-González , M. Alatorre-Ibargüengoitia
In certain circumstances, such as the imminent eruption of a volcano, it has been suggested that "large" and "near-field" earthquakes have the capacity to "accelerate", "clock-advance", or "trigger" the eruption. In contrast, these earthquakes have no effect, or a minimal effect, on a volcano that is far from erupting. Changes in earthquake rates are frequently used as a stress-meter. In this study, we compared seismic activity beneath the two most active volcanoes in Chiapas, Mexico: El Chichón and Tacaná, before and after the September 8, 2017, Mw8.2 earthquake. This comparison can provide insight into volcanic stress changes and proximity (or not) to an eruption. At El Chichón, seismicity increased a few days after the 2017 earthquake and remained elevated for five weeks before returning to pre-earthquake levels. At Tacaná, seismicity increased 15 weeks after the 2017 earthquake and remained elevated for two weeks before returning to pre-earthquake levels. This timing difference may be related to the type of fluid involved in generating the swarms: water at El Chichón and magma at Tacaná. Although the presence of volcanic seismicity indicates that El Chichón and Tacaná are seismically active, minor changes in amplitude and duration following the 2017 earthquake suggest minimal stress changes at these volcanoes. This is consistent with the absence of eruptions in 2017–2018. Previous field observations identified zones of hydrothermal manifestations at both volcanoes. These zones coincide with the locations of hydrothermal seismicity that we identified.
{"title":"Changes in stress revealed by seismic rate changes at El Chichón and Tacaná volcanoes, following the 8 September 2017, Mw8.2 Chiapas, Mexico, earthquake","authors":"D. Legrand , M. Perton , R. Campion , L. Peiffer , C. Valdés-González , M. Alatorre-Ibargüengoitia","doi":"10.1016/j.jsames.2025.105862","DOIUrl":"10.1016/j.jsames.2025.105862","url":null,"abstract":"<div><div>In certain circumstances, such as the imminent eruption of a volcano, it has been suggested that \"large\" and \"near-field\" earthquakes have the capacity to \"accelerate\", \"clock-advance\", or \"trigger\" the eruption. In contrast, these earthquakes have no effect, or a minimal effect, on a volcano that is far from erupting. Changes in earthquake rates are frequently used as a stress-meter. In this study, we compared seismic activity beneath the two most active volcanoes in Chiapas, Mexico: El Chichón and Tacaná, before and after the September 8, 2017, M<sub>w</sub>8.2 earthquake. This comparison can provide insight into volcanic stress changes and proximity (or not) to an eruption. At El Chichón, seismicity increased a few days after the 2017 earthquake and remained elevated for five weeks before returning to pre-earthquake levels. At Tacaná, seismicity increased 15 weeks after the 2017 earthquake and remained elevated for two weeks before returning to pre-earthquake levels. This timing difference may be related to the type of fluid involved in generating the swarms: water at El Chichón and magma at Tacaná. Although the presence of volcanic seismicity indicates that El Chichón and Tacaná are seismically active, minor changes in amplitude and duration following the 2017 earthquake suggest minimal stress changes at these volcanoes. This is consistent with the absence of eruptions in 2017–2018. Previous field observations identified zones of hydrothermal manifestations at both volcanoes. These zones coincide with the locations of hydrothermal seismicity that we identified.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105862"},"PeriodicalIF":1.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521144","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}
Pub Date : 2025-11-06DOI: 10.1016/j.jsames.2025.105853
Ruy Paulo Philipp , Edinei Koester , Miguel Angelo Stipp Basei , Rodrigo Fabiano Cruz , Vinicius Germano Hilgert , Daniel Triboli Vieira , Ana Paula Agostinelli
The Dom Feliciano Belt is one of the most extensive and best-preserved Neoproterozoic orogenic systems, forming a continuous belt from Santa Catarina (southern Brazil) to eastern Uruguay. Its paleogeographic significance within the West Gondwana framework has been refined over the past four decades through integrated structural, geochemical, and geochronological studies. U–Pb zircon dating, along with Sm–Nd and Lu–Hf isotopic systematics, constrain its geodynamic evolution between ∼900 and 570 Ma. Orogenic history is recorded by metavolcano-sedimentary and metaplutonic units linked to magmatic arcs and Tonian ophiolitic complexes. Pre-collisional magmatism occurred in distinct arc systems, including the intra-oceanic Passinho Arc (900–830 Ma) and the continental São Gabriel (800–730 Ma) and Piratini (800–750 Ma) arcs. Provenance and geochemical data differentiate older, mature passive-margin successions from younger, immature arc-related supracrustal assemblages. These units record syn-depositional volcanism and sedimentation, with detrital input largely derived from Tonian arcs. The Pinheiro Machado Arc (∼1000 km long) represents a major Cryogenian expression of syn-to post-collisional plutonic magmatism. It is dominated by potassic granitoids evolving from high-K calc-alkaline metaluminous to peraluminous suites, followed by shoshonitic and late-stage alkaline magmatism. Isotopic data indicate partial melting of Paleoproterozoic basement rocks and contributions from mafic tholeiitic sources, revealing hybrid magmatic origins. Metamorphic ages indicate an initial collisional phase between 730 and 720 Ma affecting the Tonian arcs, followed by a peak metamorphic event between 660 and 620 Ma, marking final oceanic closure and continental amalgamation of the Brasiliano–Pan-African orogenic cycle. Post-collisional magmatism, associated with cataclastic metamorphism, persisted from 610 to 570 Ma. These data provide critical insights into crustal growth and the tectono-magmatic assembly of Western Gondwana.
{"title":"Neoproterozoic magmatic arcs of the Dom Feliciano Belt, southern Brazil","authors":"Ruy Paulo Philipp , Edinei Koester , Miguel Angelo Stipp Basei , Rodrigo Fabiano Cruz , Vinicius Germano Hilgert , Daniel Triboli Vieira , Ana Paula Agostinelli","doi":"10.1016/j.jsames.2025.105853","DOIUrl":"10.1016/j.jsames.2025.105853","url":null,"abstract":"<div><div>The Dom Feliciano Belt is one of the most extensive and best-preserved Neoproterozoic orogenic systems, forming a continuous belt from Santa Catarina (southern Brazil) to eastern Uruguay. Its paleogeographic significance within the West Gondwana framework has been refined over the past four decades through integrated structural, geochemical, and geochronological studies. U–Pb zircon dating, along with Sm–Nd and Lu–Hf isotopic systematics, constrain its geodynamic evolution between ∼900 and 570 Ma. Orogenic history is recorded by metavolcano-sedimentary and metaplutonic units linked to magmatic arcs and Tonian ophiolitic complexes. Pre-collisional magmatism occurred in distinct arc systems, including the intra-oceanic Passinho Arc (900–830 Ma) and the continental São Gabriel (800–730 Ma) and Piratini (800–750 Ma) arcs. Provenance and geochemical data differentiate older, mature passive-margin successions from younger, immature arc-related supracrustal assemblages. These units record syn-depositional volcanism and sedimentation, with detrital input largely derived from Tonian arcs. The Pinheiro Machado Arc (∼1000 km long) represents a major Cryogenian expression of syn-to post-collisional plutonic magmatism. It is dominated by potassic granitoids evolving from high-K calc-alkaline metaluminous to peraluminous suites, followed by shoshonitic and late-stage alkaline magmatism. Isotopic data indicate partial melting of Paleoproterozoic basement rocks and contributions from mafic tholeiitic sources, revealing hybrid magmatic origins. Metamorphic ages indicate an initial collisional phase between 730 and 720 Ma affecting the Tonian arcs, followed by a peak metamorphic event between 660 and 620 Ma, marking final oceanic closure and continental amalgamation of the Brasiliano–Pan-African orogenic cycle. Post-collisional magmatism, associated with cataclastic metamorphism, persisted from 610 to 570 Ma. These data provide critical insights into crustal growth and the tectono-magmatic assembly of Western Gondwana.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105853"},"PeriodicalIF":1.5,"publicationDate":"2025-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521112","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}
Pub Date : 2025-11-05DOI: 10.1016/j.jsames.2025.105859
Emiliano Castro de Oliveira , Lucieth Cruz Vieira , Gabriella Talamo Fontaneta , Francisco Hilário Bezerra
This study documents the first occurrence of vanished evaporites in the Caatinga Formation (Irecê Basin, NE Brazil), unveiling novel paleoenvironmental and diagenetic processes in a continental carbonate system. Stratigraphic and petrographic analyses reveal previously unrecognized textures, including teepee structures and collapse/solution breccias, alongside with gypsum and halite pseudomorphs. Three key outcrop areas (Verde, Jacaré, Salitre rivers) expose a sedimentary succession comprising: (1) basal muddy micrites with sediment infiltration, (2) brecciated mudstones/wackestones, (3) brecciated wackestones/packestones, (4) an unconsolidated pedogenic horizon and (5) a regionally extensive calcrete layer caps the succession. Overlying tufa deposits, previously linked to the Caatinga Formation, are reinterpreted as younger freshwater carbonates. These findings provide critical evidence for a evaporitic sedimentary system, that can be related to the last marine incursion in the region, during the Early Cretaceous. The study also demonstrates that continental carbonates can archive cryptic evaporitic histories, offering new insights into paleoenvironment evolution in evaporite-influenced successions.
{"title":"When the Salt Vanished: Unveiling evaporite record in the continental carbonate succession of Caatinga Formation (Early Cretaceous, Irece basin, northeastern Brazil)","authors":"Emiliano Castro de Oliveira , Lucieth Cruz Vieira , Gabriella Talamo Fontaneta , Francisco Hilário Bezerra","doi":"10.1016/j.jsames.2025.105859","DOIUrl":"10.1016/j.jsames.2025.105859","url":null,"abstract":"<div><div>This study documents the first occurrence of vanished evaporites in the Caatinga Formation (Irecê Basin, NE Brazil), unveiling novel paleoenvironmental and diagenetic processes in a continental carbonate system. Stratigraphic and petrographic analyses reveal previously unrecognized textures, including teepee structures and collapse/solution breccias, alongside with gypsum and halite pseudomorphs. Three key outcrop areas (Verde, Jacaré, Salitre rivers) expose a sedimentary succession comprising: (1) basal muddy micrites with sediment infiltration, (2) brecciated mudstones/wackestones, (3) brecciated wackestones/packestones, (4) an unconsolidated pedogenic horizon and (5) a regionally extensive calcrete layer caps the succession. Overlying tufa deposits, previously linked to the Caatinga Formation, are reinterpreted as younger freshwater carbonates. These findings provide critical evidence for a evaporitic sedimentary system, that can be related to the last marine incursion in the region, during the Early Cretaceous. The study also demonstrates that continental carbonates can archive cryptic evaporitic histories, offering new insights into paleoenvironment evolution in evaporite-influenced successions.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105859"},"PeriodicalIF":1.5,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521148","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}
Pub Date : 2025-11-05DOI: 10.1016/j.jsames.2025.105860
Mariana de Matheus Marques Dos Santos, Cláudia Regina Passarelli, Antonio Roberto Saad, Paulo Roberto dos Santos, Miguel Ângelo Stipp Basei, Lucas Martins Lino
This study investigates the origin of Permian volcanic ash layers preserved in the sedimentary units of the Paraná Basin (PB), Brazil, and Uruguay, through the integration of U-Pb geochronology, Lu-Hf isotopes, and trace element data in zircon. The aim is to evaluate a possible genetic link between these ash layers and volcanic rocks of the Choiyoi Igneous Province (CIP) in western Argentina. A total of 183 zircon spots were analyzed - 129 from PB formations (Rio Bonito, Irati, Mangrullo, Estrada Nova, Teresina, and Rio do Rasto) and 54 from CIP units (El Imperial, Cerro Carrizalito, Agua de los Burros) - using previously dated grains by SHRIMP. Zircons from the main Permian PB units, e.g. Irati, Estrada Nova and Rio do Rasto Formation, show crystallization ages between 274 and 269 Ma, εHf(t) values ranging from −6 to +4, and crustal model ages (TDMc) between 1400 and 1100 Ma. These values are compatible with those from intermediate and upper Choiyoi units, which show zircon ages between 264 and 251 Ma and similar isotopic signatures within uncertainties. Zircons from the Rio Bonito Formation mostly yielded older Carboniferous ages (304-302 Ma), suggesting a different volcanic source, with a minor Permian population (∼298-297 Ma). The El Imperial Formation includes most Ordovician zircons (483-450 Ma) and one younger Permian grain (∼297 Ma), possibly reflecting recycling of older crustal sources, such as the Famatinian or Ocloyic belts. Geochemical proxies (Th/U, Ce/Ce∗, Eu/Eu∗, Zr/Hf) and textures support a volcanic origin for the zircon crystals, which exhibit calc-alkaline compositional signatures and crystallization under oxidizing conditions, and lack evidence for abrasion owing to sedimentary transportation. The overlap in their crystallization age, isotopic composition, and trace elements between PB and CIP zircons points to a shared magmatic history. The data suggests that the CIP was likely a primary source of ash for the PB during the Permian, while older ash layers may be linked to earlier, unrecognized magmatic episodes.
{"title":"Tracing the origin of Permian volcanic ash fall layers in the Paraná Basin using zircon U-Pb ages, Lu-Hf isotopes, and trace element contents","authors":"Mariana de Matheus Marques Dos Santos, Cláudia Regina Passarelli, Antonio Roberto Saad, Paulo Roberto dos Santos, Miguel Ângelo Stipp Basei, Lucas Martins Lino","doi":"10.1016/j.jsames.2025.105860","DOIUrl":"10.1016/j.jsames.2025.105860","url":null,"abstract":"<div><div>This study investigates the origin of Permian volcanic ash layers preserved in the sedimentary units of the Paraná Basin (PB), Brazil, and Uruguay, through the integration of U-Pb geochronology, Lu-Hf isotopes, and trace element data in zircon. The aim is to evaluate a possible genetic link between these ash layers and volcanic rocks of the Choiyoi Igneous Province (CIP) in western Argentina. A total of 183 zircon spots were analyzed - 129 from PB formations (Rio Bonito, Irati, Mangrullo, Estrada Nova, Teresina, and Rio do Rasto) and 54 from CIP units (El Imperial, Cerro Carrizalito, Agua de los Burros) - using previously dated grains by SHRIMP. Zircons from the main Permian PB units, <em>e.g.</em> Irati, Estrada Nova and Rio do Rasto Formation, show crystallization ages between 274 and 269 Ma, εHf<sub>(t)</sub> values ranging from −6 to +4, and crustal model ages (T<sub>DM</sub><sup>c</sup>) between 1400 and 1100 Ma. These values are compatible with those from intermediate and upper Choiyoi units, which show zircon ages between 264 and 251 Ma and similar isotopic signatures within uncertainties. Zircons from the Rio Bonito Formation mostly yielded older Carboniferous ages (304-302 Ma), suggesting a different volcanic source, with a minor Permian population (∼298-297 Ma). The El Imperial Formation includes most Ordovician zircons (483-450 Ma) and one younger Permian grain (∼297 Ma), possibly reflecting recycling of older crustal sources, such as the Famatinian or Ocloyic belts. Geochemical proxies (Th/U, Ce/Ce∗, Eu/Eu∗, Zr/Hf) and textures support a volcanic origin for the zircon crystals, which exhibit calc-alkaline compositional signatures and crystallization under oxidizing conditions, and lack evidence for abrasion owing to sedimentary transportation. The overlap in their crystallization age, isotopic composition, and trace elements between PB and CIP zircons points to a shared magmatic history. The data suggests that the CIP was likely a primary source of ash for the PB during the Permian, while older ash layers may be linked to earlier, unrecognized magmatic episodes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105860"},"PeriodicalIF":1.5,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521145","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}
Pub Date : 2025-11-05DOI: 10.1016/j.jsames.2025.105861
María Victoria Sánchez , Juan Pablo Ariza , Federico Lince Klinger , Florencia L. Boedo , Mario Giménez , Graciela I. Vujovich
In central-western Argentina, an early Paleozoic belt comprising mafic and ultramafic rocks spatially associated with metasedimentary successions is exposed along the western margin of the Argentine Precordillera. In this study, we integrate structural and geophysical datasets to constrain the three-dimensional geometry of the southern sector of the Precordillera mafic-ultramafic belt, with focus on in the Sierra de Bonilla area. Structural analysis in the Quebrada Santa Elena evidences polyphase ductile deformation with sinistral shear components, while gravity and magnetic modeling reveal pronouced density and magnetic susceptibility contrasts consistent with the presence of serpentinite lenses at depth. This work refines the understanding of the crustal architecture of the southern Precordillera and provides new insights into the accretionary processes active along the Gondwanan margin during the early Paleozoic.
在阿根廷中西部，沿阿根廷前科迪勒拉西缘暴露出一条由基性岩和超基性岩组成的早古生代带，在空间上与变质沉积序列相关。在这项研究中，我们整合了结构和地球物理数据集，以限制Precordillera基性-超基性带南段的三维几何形状，重点是Sierra de Bonilla地区。在Quebrada Santa Elena的构造分析中，发现了具有左旋剪切分量的多相韧性变形，而重力和磁模拟显示了明显的密度和磁化率对比，与深部蛇纹岩透镜的存在相一致。这项工作完善了对南前科迪勒拉地壳结构的认识，并为早古生代活跃在冈瓦南边缘的增生过程提供了新的认识。
{"title":"Structural geology and geophysical constraints of the central-north part of the Sierra de Bonilla, Southern Precordillera, Argentina","authors":"María Victoria Sánchez , Juan Pablo Ariza , Federico Lince Klinger , Florencia L. Boedo , Mario Giménez , Graciela I. Vujovich","doi":"10.1016/j.jsames.2025.105861","DOIUrl":"10.1016/j.jsames.2025.105861","url":null,"abstract":"<div><div>In central-western Argentina, an early Paleozoic belt comprising mafic and ultramafic rocks spatially associated with metasedimentary successions is exposed along the western margin of the Argentine Precordillera. In this study, we integrate structural and geophysical datasets to constrain the three-dimensional geometry of the southern sector of the Precordillera mafic-ultramafic belt, with focus on in the Sierra de Bonilla area. Structural analysis in the Quebrada Santa Elena evidences polyphase ductile deformation with sinistral shear components, while gravity and magnetic modeling reveal pronouced density and magnetic susceptibility contrasts consistent with the presence of serpentinite lenses at depth. This work refines the understanding of the crustal architecture of the southern Precordillera and provides new insights into the accretionary processes active along the Gondwanan margin during the early Paleozoic.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105861"},"PeriodicalIF":1.5,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521147","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}
Pub Date : 2025-11-04DOI: 10.1016/j.jsames.2025.105857
Cloves Vilas Boas dos Santos , Josiclêda Domiciano Galvíncio , Rodrigo de Queiroga Miranda , Herica Fernanda de Sousa Carvalho , Alzira Gabrielle Soares Saraiva Souza , Inajá Francisco de Sousa , Magna Soelma Beserra de Moura
Soil moisture is a key variable in the hydrological cycle, influencing water, soil, and energy exchanges between the land surface and the atmosphere. This study aimed to develop simplified equations and validate satellite-based soil moisture estimates in seasonally dry tropical forest areas. The study area included part of Petrolina-PE, Brazil, where a preserved Caatinga vegetation site provided surface observations. Daily-resolution satellite data were obtained from SMAP (9 km), SMOS (25 km; ascending and descending), and ESA CCI SM (25 km; combined). Validation was performed by comparing satellite pixel values with surface measurements. Initially, linear models were created and assessed using the correlation coefficient (r). Our results showed the SMAP achieved r = 0.80; SMOS ranged from r = 0.68 (ascending) to r = 0.69 (descending); and ESA CCI SM reached r = 0.61. Further validation employed r, RMSE, RSMD, MAE, and PBIAS. SMAP performed best, yielding r = 0.85, RMSE and RSMD = 0.01 m3 m−3, MAE = 0.01 m3 m−3, and PBIAS = −2.50. SMOS results were also satisfactory, with r = 0.76 (ascending) and r = 0.75 (descending), RMSE/RSMD = 0.01–0.02 m3 m−3, MAE = 0.01 m3 m−3, and PBIAS = −1.80 to −3.00. ESA CCI SM showed lower correlation (r = 0.41), though error metrics remained within acceptable ranges. Overall, SMAP and SMOS data accurately estimated daily and hourly soil moisture in dry tropical forests. Despite moderate correlation, ESA CCI SM remains useful for long-term analysis due to its historical coverage (1978–2022, version v08.1).
土壤湿度是水循环的关键变量，影响着地表与大气之间的水、土壤和能量交换。本研究旨在建立简化方程并验证基于卫星的季节性干旱热带森林地区土壤湿度估算。研究区域包括巴西Petrolina-PE的一部分，在那里保存的Caatinga植被遗址提供了地面观测。日分辨率卫星数据来自SMAP （9 km）、SMOS （25 km，上升和下降）和ESA CCI SM （25 km，组合）。通过比较卫星像素值与地面测量值进行验证。最初，建立线性模型并使用相关系数(r)进行评估。我们的结果显示，SMAP达到r = 0.80；SMOS范围为r = 0.68（上升）~ r = 0.69（下降）；ESA CCI SM达到r = 0.61。进一步验证采用r、RMSE、RSMD、MAE和PBIAS。SMAP表现最佳，产率r = 0.85， RMSE和RSMD = 0.01 m3 m - 3, MAE = 0.01 m3 m - 3, PBIAS = - 2.50。SMOS结果也令人满意，r = 0.76（上升）和r = 0.75（下降），RMSE/RSMD = 0.01 - 0.02 m3 m - 3, MAE = 0.01 m3 m - 3, PBIAS = - 1.80 ~ - 3.00。ESA CCI SM的相关性较低（r = 0.41），但误差指标仍在可接受的范围内。总的来说，SMAP和SMOS数据准确地估计了干燥热带森林的日和时土壤湿度。尽管存在适度的相关性，但由于其历史覆盖范围（1978-2022，版本v08.1）， ESA CCI SM仍然对长期分析有用。
{"title":"Validation of SMAP, SMOS, and ESA CCI SM soil moisture products in a seasonally dry tropical forest","authors":"Cloves Vilas Boas dos Santos , Josiclêda Domiciano Galvíncio , Rodrigo de Queiroga Miranda , Herica Fernanda de Sousa Carvalho , Alzira Gabrielle Soares Saraiva Souza , Inajá Francisco de Sousa , Magna Soelma Beserra de Moura","doi":"10.1016/j.jsames.2025.105857","DOIUrl":"10.1016/j.jsames.2025.105857","url":null,"abstract":"<div><div>Soil moisture is a key variable in the hydrological cycle, influencing water, soil, and energy exchanges between the land surface and the atmosphere. This study aimed to develop simplified equations and validate satellite-based soil moisture estimates in seasonally dry tropical forest areas. The study area included part of Petrolina-PE, Brazil, where a preserved Caatinga vegetation site provided surface observations. Daily-resolution satellite data were obtained from SMAP (9 km), SMOS (25 km; ascending and descending), and ESA CCI SM (25 km; combined). Validation was performed by comparing satellite pixel values with surface measurements. Initially, linear models were created and assessed using the correlation coefficient (<em>r</em>). Our results showed the SMAP achieved <em>r</em> = 0.80; SMOS ranged from <em>r</em> = 0.68 (ascending) to <em>r</em> = 0.69 (descending); and ESA CCI SM reached <em>r</em> = 0.61. Further validation employed <em>r</em>, RMSE, RSMD, MAE, and PBIAS. SMAP performed best, yielding <em>r</em> = 0.85, RMSE and RSMD = 0.01 m<sup>3</sup> m<sup>−3</sup>, MAE = 0.01 m<sup>3</sup> m<sup>−3</sup>, and PBIAS = −2.50. SMOS results were also satisfactory, with <em>r</em> = 0.76 (ascending) and <em>r</em> = 0.75 (descending), RMSE/RSMD = 0.01–0.02 m<sup>3</sup> m<sup>−3</sup>, MAE = 0.01 m<sup>3</sup> m<sup>−3</sup>, and PBIAS = −1.80 to −3.00. ESA CCI SM showed lower correlation (<em>r</em> = 0.41), though error metrics remained within acceptable ranges. Overall, SMAP and SMOS data accurately estimated daily and hourly soil moisture in dry tropical forests. Despite moderate correlation, ESA CCI SM remains useful for long-term analysis due to its historical coverage (1978–2022, version v08.1).</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105857"},"PeriodicalIF":1.5,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521106","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}
Pub Date : 2025-11-04DOI: 10.1016/j.jsames.2025.105858
Julián D. Rolan , Sofía A. Santibañez , Nemesio Heredia , Norberto J. Uriz , Jonatan A. Arnol , Nicole Gonzalez Olarte , Miguel A.S. Basei , Carlos A. Cingolani , Maximiliano Naipauer
The Neopaleozoic sedimentary record exposed in the eastern flank of the Cordón del Plata (Frontal Cordillera of Mendoza, Argentina) provides a valuable archive for reconstructing the geodynamic evolution of the southwestern Gondwana margin. In this study, we present new stratigraphic, petrographic and detrital zircon U-Pb data from the Loma de Los Morteritos and El Plata formations and the Río Blanco Conglomerate. Our results enable the refinement of the existing chronostratigraphic framework of the region and provide new insights into the timing of the San Rafael Orogenic Phase at the end of the Gondwanan Orogenic Cycle. A maximum depositional age of 299 ± 3 Ma (Gzhelian) was obtained for the upper section of the Loma de Los Morteritos Formation, confirming a latest Carboniferous age for the unit. The Río Blanco Formation yielded a younger age of 266 ± 2.1 Ma (Guadalupian), constraining its deposition to the Permian and confirming its inclusion in the lower section of the Choiyoi Group. The provenance analysis reveals that the Loma de los Morteritos Formation was primarily fed by erosion of the eastern remnant topographic highs, particularly the exhumed relicts of the Protoprecordillera. However, the presence of Carboniferous zircon grains suggests a subordinate contribution from western sources, likely associated with Coastal and Elqui-Limarí batholiths. In contrast, the Río Blanco Conglomerate records a more localized provenance, mainly fed by the recycling of the Carboniferous substrate. Overall, our findings constrain the timing of the San Rafael Phase in the Cordón del Plata to a 22 Ma interval, between 299 and 277 Ma.
阿根廷门多萨（Mendoza）的Cordón del Plata （Frontal Cordillera）东侧的新古宙沉积记录为重建冈瓦纳（Gondwana）西南边缘的地球动力学演化提供了宝贵的资料。在这项研究中，我们获得了来自Loma de Los Morteritos和El Plata组以及Río Blanco砾岩的新的地层、岩石学和碎屑锆石U-Pb数据。我们的研究结果能够完善该地区现有的年代地层格架，并为冈瓦南造山旋回末期圣拉斐尔造山期的时间提供新的见解。Loma de Los Morteritos组上段的最大沉积年龄为299±3 Ma (Gzhelian)，确定了该单元最晚的石炭世年龄。Río Blanco组的年龄更小，为266±2.1 Ma (Guadalupian)，将其沉积限制在二叠纪，并确认其包含在Choiyoi群的下部。物源分析表明，洛马-德-洛斯-莫特里托斯组主要是由东部残余地形高点，特别是原recordillera出土遗迹的侵蚀作用形成的。然而，石炭系锆石颗粒的存在表明来自西部的次要贡献，可能与海岸和Elqui-Limarí岩基有关。相比之下，Río Blanco砾岩的物源较为局限，主要由石炭纪基底的再循环供给。总体而言，我们的研究结果将Cordón del Plata的圣拉斐尔阶段的时间限制在299至277 Ma之间的22 Ma区间。
{"title":"New insights into the San Rafael orogenic phase: U-Pb age constraints and sedimentary provenance of Neopaleozoic deposits from the eastern Cordón del Plata, Frontal Cordillera of Mendoza, Argentina","authors":"Julián D. Rolan , Sofía A. Santibañez , Nemesio Heredia , Norberto J. Uriz , Jonatan A. Arnol , Nicole Gonzalez Olarte , Miguel A.S. Basei , Carlos A. Cingolani , Maximiliano Naipauer","doi":"10.1016/j.jsames.2025.105858","DOIUrl":"10.1016/j.jsames.2025.105858","url":null,"abstract":"<div><div>The Neopaleozoic sedimentary record exposed in the eastern flank of the Cordón del Plata (Frontal Cordillera of Mendoza, Argentina) provides a valuable archive for reconstructing the geodynamic evolution of the southwestern Gondwana margin. In this study, we present new stratigraphic, petrographic and detrital zircon U-Pb data from the Loma de Los Morteritos and El Plata formations and the Río Blanco Conglomerate. Our results enable the refinement of the existing chronostratigraphic framework of the region and provide new insights into the timing of the San Rafael Orogenic Phase at the end of the Gondwanan Orogenic Cycle. A maximum depositional age of 299 ± 3 Ma (Gzhelian) was obtained for the upper section of the Loma de Los Morteritos Formation, confirming a latest Carboniferous age for the unit. The Río Blanco Formation yielded a younger age of 266 ± 2.1 Ma (Guadalupian), constraining its deposition to the Permian and confirming its inclusion in the lower section of the Choiyoi Group. The provenance analysis reveals that the Loma de los Morteritos Formation was primarily fed by erosion of the eastern remnant topographic highs, particularly the exhumed relicts of the Protoprecordillera. However, the presence of Carboniferous zircon grains suggests a subordinate contribution from western sources, likely associated with Coastal and Elqui-Limarí batholiths. In contrast, the Río Blanco Conglomerate records a more localized provenance, mainly fed by the recycling of the Carboniferous substrate. Overall, our findings constrain the timing of the San Rafael Phase in the Cordón del Plata to a 22 Ma interval, between 299 and 277 Ma.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105858"},"PeriodicalIF":1.5,"publicationDate":"2025-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145469020","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}
Pub Date : 2025-11-03DOI: 10.1016/j.jsames.2025.105848
José, Renato Derntl, Karen, Badaraco Costa, Felipe Antônio de Lima Toledo
Changes in insolation driven by variations in Earth's orbital parameters, eccentricity, axial tilt (obliquity), and precession, as described in Milankovitch theory, are key drivers of long-period climate fluctuations that characterize the Late Pleistocene (∼800 thousand years - kyr). However, these orbital components do not influence global climate linearly, and records of stable carbon isotopes (δ13C) often exhibit responses that are decoupled from insolation trends. Understanding the causes of this decoupling is critical to deciphering the dynamics of the global climate system. This study investigates the expression of orbital forcing in benthic foraminiferal δ13C records from core GL-854 over the past 772 kyr. The data are compared with records from core ODP-1088 and the South Atlantic δ13C Stack, spanning the subtropical South Atlantic. Spectral and amplitude analyses indicate that the records are internally coherent in the eccentricity band (∼100 kyr), but decoupled from insolation. In the obliquity band (∼41 kyr), core GL-854 exhibits a pronounced amplitude increase after the Mid-Brunhes Event (MBE: ∼430 kyr), while obliquity-related insolation shows only minor variability. In the precession bands (∼23 kyr and ∼19 kyr), the records display contrasting patterns, suggesting strong regional modulation. East-west differences in oceanic δ13C cycles indicates that the subtropical south Atlantic can present different responses due to regional and local feedback mechanisms. These results suggest that while orbital insolation acts as the primary driver of glacial-interglacial climate changes, internal feedback mechanisms such as ocean ventilation, thermohaline circulation, and albedo, modulate the intensity and pacing of these cycles, especially after the MBE.
{"title":"Carbon cycle dynamics in the subtropical South Atlantic: orbital pacing and regional modulation over the last 772 kyr","authors":"José, Renato Derntl, Karen, Badaraco Costa, Felipe Antônio de Lima Toledo","doi":"10.1016/j.jsames.2025.105848","DOIUrl":"10.1016/j.jsames.2025.105848","url":null,"abstract":"<div><div>Changes in insolation driven by variations in Earth's orbital parameters, eccentricity, axial tilt (obliquity), and precession, as described in Milankovitch theory, are key drivers of long-period climate fluctuations that characterize the Late Pleistocene (∼800 thousand years - kyr). However, these orbital components do not influence global climate linearly, and records of stable carbon isotopes (δ<sup>13</sup>C) often exhibit responses that are decoupled from insolation trends. Understanding the causes of this decoupling is critical to deciphering the dynamics of the global climate system. This study investigates the expression of orbital forcing in benthic foraminiferal δ<sup>13</sup>C records from core GL-854 over the past 772 kyr. The data are compared with records from core ODP-1088 and the South Atlantic δ<sup>13</sup>C Stack, spanning the subtropical South Atlantic. Spectral and amplitude analyses indicate that the records are internally coherent in the eccentricity band (∼100 kyr), but decoupled from insolation. In the obliquity band (∼41 kyr), core GL-854 exhibits a pronounced amplitude increase after the Mid-Brunhes Event (MBE: ∼430 kyr), while obliquity-related insolation shows only minor variability. In the precession bands (∼23 kyr and ∼19 kyr), the records display contrasting patterns, suggesting strong regional modulation. East-west differences in oceanic δ<sup>13</sup>C cycles indicates that the subtropical south Atlantic can present different responses due to regional and local feedback mechanisms. These results suggest that while orbital insolation acts as the primary driver of glacial-interglacial climate changes, internal feedback mechanisms such as ocean ventilation, thermohaline circulation, and albedo, modulate the intensity and pacing of these cycles, especially after the MBE.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105848"},"PeriodicalIF":1.5,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145435610","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}
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