Journal of South American Earth Sciences最新文献

{"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}

{"title":"New insights into hydrothermal alteration in the Ag-Pb-Zn Chinchillas deposit, Northwestern Argentina","authors":"Maximiliano Mercado ,&nbsp;D. Beaufort ,&nbsp;P.J. Caffe ,&nbsp;P. Patrier ,&nbsp;M. Franchini ,&nbsp;H. Caranza ,&nbsp;R.I. Zapata","doi":"10.1016/j.jsames.2025.105467","DOIUrl":"10.1016/j.jsames.2025.105467","url":null,"abstract":"<div><div>Hydrothermal alteration and ore deposition at Chinchillas (northern Puna, Argentina) occurred in pyroclastic deposits that fill an explosive diatreme, as well as in monomictic breccias composed of metasedimentary lithoclasts from the basement that bound the diatreme. Highly porous and permeable rocks acted as reservoir for hydrothermal fluids responsible of alteration and mineralization. Sequential mineral associations can be grouped in three pre- and two syn-to post-mineralization stages, which are frequently superimposed in space. The first stage (adularia-rich) is widespread and develops in a context of alkaline solutions, followed by upward circulation of relatively acidic and reducing fluids (second stage) with B availability (tourmaline ± pyrite ± quartz), limited to deep sectors. A third alteration stage is typical of the argillic alteration association and is given by kaolinite replaced by later illite + illite-smectite mixed-layers + quartz ± anatase ± pyrite ± alumino-phosfate-sulfates, which indicates the progressive neutralization of fluids during continuous interaction with rocks. The crystal structure characteristics and zonation of clay minerals with depth suggest temperatures between 200° and 170 °C and a vertical thermal gradient during illitization. These stages seem to have had minor effects on the reservoir quality of the diatreme, as the Ag-Pb-Zn ore + siderite (mineralization stage) was deposited in two relatively large areas of the diatreme, and late siderite (post-mineralization stage) is ubiquitous in both mineralized and barren areas.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105467"},"PeriodicalIF":1.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621128","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":"Land use and land cover analysis with special reference to mangrove dynamics for sustainable use in the Rosario River sub-basin, Pixvae, Panama","authors":"Jaime Rivera-Solís ,&nbsp;Adolfo Quesada-Román ,&nbsp;Rosa G. Castillero","doi":"10.1016/j.jsames.2025.105464","DOIUrl":"10.1016/j.jsames.2025.105464","url":null,"abstract":"<div><div>Effective land use planning necessitates integrating environmental parameters to assess spatial patterns and ecosystem conditions, particularly in vulnerable coastal regions. Mangrove ecosystems provide critical ecological services, yet they face increasing threats from anthropogenic pressures. This study combines remote sensing and field-based structural analysis to classify land cover and assess mangrove conditions in Ensenada de Rosario in Panama, supporting environmental planning. Using high-resolution PlanetScope satellite imagery within the ArcGIS Pro environment, we applied spectral analysis through the Normalized Difference Vegetation Index (NDVI) to classify land cover into five spectral classes and quantify four primary land use categories. Field validation in July 2023 involved four 10 × 10 m quadrants spaced 50 m apart, where mangrove species were identified, and structural parameters—including diameter at breast height (DBH), tree height, volume, basal area (BA), and density—were measured. Results indicate that the mangrove is a fringe type dominated by Rhizophora mangle, covering 24.7% of the sub-basin, while the anthroponatural landscape accounts for 3.2%. Structural analysis revealed an average DBH of 14.3 ± 2.6 cm, mean tree height of 6.8 ± 1.4 m, and basal area of 18.5 ± 3.2 m²/ha, indicating moderate forest development. Model uncertainties were estimated at ±5% for NDVI classification and ±10% for structural parameter measurements. These findings underscore the value of integrating remote sensing and field verification for land use classification and mangrove conservation, providing a methodological framework for balancing development with ecological sustainability in coastal environments.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105464"},"PeriodicalIF":1.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611551","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":"A simple method to discriminate non-seismic pulses and long-period noise in broadband seismic records and its application to centroid moment tensor inversion of earthquakes in Colombia","authors":"Viviana Dionicio ,&nbsp;Hiroyuki Kumagai ,&nbsp;Juan Carlos Bermudez ,&nbsp;Esteban Poveda ,&nbsp;Faustino Blanco ,&nbsp;Masahiro Yoshimoto ,&nbsp;Maeda Yuta ,&nbsp;Orlando Chamorro ,&nbsp;Patricia Pedraza ,&nbsp;Indira Molina","doi":"10.1016/j.jsames.2025.105466","DOIUrl":"10.1016/j.jsames.2025.105466","url":null,"abstract":"<div><div>Non-seismic pulses and long-period noise are artifacts produced by broadband seismometers and degrade centroid moment tensor (CMT) solutions of earthquakes estimated from waveform inversion. In addition to the source amplitude ratio proposed by a previous study, we found that kurtosis is useful for discriminating artifacts from seismic signals. For 157 tectonic earthquakes with moment magnitudes of 4.6–7.5 in and around Colombia in 2014–2022, we manually selected waveforms from the Colombian broadband seismic network and estimated CMT solutions by waveform inversion in a long-period (50−200 s) band. We found that 98% of the selected waveforms had kurtosis values and signal-to-noise ratios larger than 2.5 and 3, respectively, and 92% had source amplitude ratios smaller than 11. We used these values as thresholds and automatically selected waveforms using the three parameters for the 157 earthquakes. Their CMT solutions showed a clear improvement compared to those estimated without any selection. They were better than those estimated with the previous method using only the source amplitude and the signal-to-noise ratios. The proposed parameters were implemented to obtain real-time automatic solutions that were similar to corresponding manual CMT solutions, and 87% of them were estimated within 20 min. Our simple method based on the statistical parameters applied to automatic CMT inversion contributes to improved earthquake monitoring and tsunami warnings in Colombina.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105466"},"PeriodicalIF":1.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561989","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":"Petrogenesis, magmatic evolution of the Morro de São João Alkaline Massif, southeastern Brazil, and implications for the evolution of the South American Platform","authors":"Mariana Bessa Fagundes ,&nbsp;Anderson Costa dos Santos ,&nbsp;Mauro Geraldes ,&nbsp;Sérgio de Castro Valente ,&nbsp;Gabriela Rodrigues Caitano ,&nbsp;Eduardo Reis Viana Rocha-Júnior","doi":"10.1016/j.jsames.2025.105456","DOIUrl":"10.1016/j.jsames.2025.105456","url":null,"abstract":"<div><div>The Morro de São João Alkaline Massif, Meso-Cenozoic, is an alkaline intrusion of approximately 10 km², located within the Poços de Caldas – Cabo Frio Alkaline Alignment. The massif consists of metaluminous rocks, ultrabasic to intermediate, potassic to ultrapotassic, SiO₂-undersaturated, and occasionally intersected by hypabyssal rocks, associated or not with pseudoleucite. The rocks of the massif are olivine-free and rich in nepheline, alkali-feldspar, and titanium- and calcium-bearing minerals. The (Dy/Yb)_N <em>vs.</em> (La/Yb)_N ratios suggest that the partial melting responsible for generating the massif occurred at approximately 1% of a garnet-bearing spinel peridotite. Meanwhile, isotopic ratios indicate that this source results from a mixture of up to 71.95 % of the EM I end-member, with influences from DMM, HIMU, and carbonatite. The magmatic evolution of the massif was not driven exclusively by fractional crystallization; the observed mineralogical and lithological diversity reflects complex processes of crustal assimilation and magma mixing. Evidence of these processes is provided by high ratios of ⁸⁷Sr/⁸⁶Sr, Ba/Sr and Rb/Sr, as well as low ratios of P₂O₅/K₂O, in addition to distinctive mineral textures such as compositional zoning in garnet and clinopyroxene crystals, poikilitic textures in amphiboles, and geochemical modeling of trace elements suggesting that the nepheline-monzosyenite, a hybrid member of the massif, contains up to 32% mafic contribution from malignite.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"156 ","pages":"Article 105456"},"PeriodicalIF":1.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529296","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":"Integrating geospatial techniques and machine learning for assessing soil erosion and associated geomorphic risks","authors":"Priyadharshini V.M. ,&nbsp;Ghadah Aldehim ,&nbsp;Noha Negm ,&nbsp;S. Subathradevi","doi":"10.1016/j.jsames.2025.105463","DOIUrl":"10.1016/j.jsames.2025.105463","url":null,"abstract":"<div><div>Soil erosion is a critical environmental issue that threatens sustainability, agriculture, and infrastructure, necessitating a precise evaluation of geomorphic risks. This study employs an integrated approach combining geospatial techniques and machine learning models to assess soil erosion exposure in the Colima area. A comprehensive dataset of geospatial parameters, including inclination angle, land use/land cover (LULC), topographic wetness index (TWI), geological formation, proximity to roads and waterbodies, terrain elevation, aspect, sunlight exposure (HillShade), soil classification, vegetation index (NDVI), terrain ruggedness index (TRI), and sediment transport index (STI), was utilized to capture the spatial variability influencing erosion processes. Machine learning models—CatBoost, AdaBoost, Convolutional Neural Networks (CNN), and Stacking—were evaluated for their predictive performance using sensitivity, specificity, specificity, F1 score, recall, and precision metrics. Among these models, CNN achieved the highest accuracy, with sensitivity, specificity, F1 score, recall, and precision values of 0.84, 0.92, 0.90, 0.84, and 0.93, respectively. The CNN model's ability to capture complex spatial relationships and patterns in the dataset underscores its suitability for erosion risk assessment. The findings indicate that terrain elevation, LULC, and NDVI are key determinants of soil erosion susceptibility. High-risk areas were associated with steep slopes, sparse vegetation cover, and proximity to waterbodies. Canoas, Camoltan De Miraflores, Chandiablo, and Jalipa have been identified as areas facing significant soil erosion risks. These regions exhibit steep slopes, sparse vegetation cover, and proximity to water bodies, making them highly susceptible to erosion. The study's findings provide valuable insights for implementing targeted erosion control measures and sustainable land management strategies in these vulnerable areas. The study provides an efficient framework for identifying erosion-prone zones and prioritizing mitigation measures, contributing to sustainable land management strategies. By leveraging advanced machine learning techniques and geospatial analysis, this research advances the predictive modelling of geomorphic risks and aids in the development of targeted erosion control interventions.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"156 ","pages":"Article 105463"},"PeriodicalIF":1.7,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551627","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":"Geochronology and stratigraphy of the Boa Vista de Minas Group: An example of a Meso-to Neoarchean greenstone-belt in amphibolite-to granulite-facies","authors":"Renato de Assis Barros ,&nbsp;Renato Moraes ,&nbsp;Marco Aurélio Piacentini Pinheiro ,&nbsp;Ciro Duarte de Carvalho ,&nbsp;Cristiano de Carvalho Lana","doi":"10.1016/j.jsames.2025.105459","DOIUrl":"10.1016/j.jsames.2025.105459","url":null,"abstract":"<div><div>The Boa Vista de Minas Group is a suite of metamorphic rocks ranging from amphibolite to granulite facies. It appears as disrupted, folded, and keel-shaped bands amidst the metagranite-migmatite domes of the Divinópolis Complex. It is challenging to define its lithostratigraphic architecture and thickness due to intense weathering and tectonic overprints. The internal organization of the complex is characterized by three main Formations. The basal level, known as the Nova Serrana Formation, primarily consists of amphibolites and mafic granulites (metabasites), meta-ultramafic rocks, cummingtonite schists, and cordierite-anthophyllite schists (immature volcanogenic metagraywackes). Zircon U-Pb analysis (LA-ICP-MS) from a sample of cordierite-anthophyllite schists from the Nova Serrana Formation yielded a maximum deposition age of <em>ca.</em> 2.82 Ga. Orthopyroxene-bearing iron formations and ferruginous meta-cherts define interbedded layers within the basal sections, collectively referred to as the Córrego do Cedro Formation. Above these units lies the Igaratinga Formation, which consists of calc-silicate rocks interspersed with lenses of amphibolites and granulites, sillimanite gneisses, and meta-ultramafic rocks, including common lenses of biotite-orthopyroxene granulite (immature volcanogenic metagraywackes). A sample of biotite- orthopyroxene granulite from this Formation provided a maximum deposition age of <em>ca.</em> 2.72 Ga (U-Pb, LA-ICP-MS). Additionally, zircon rims showing light luminescence and newly formed zircon yielded a Concordia age of approximately 2.0 Ga, interpreted as reflecting a high-grade metamorphic overprint. The patterns of LREE enrichment, Nb-Ta-Ti depletions, and variable Th/Nb ratios observed in the metabasic rocks of both the Nova Serrana and Igaratinga Formations are similar to those formed under interactions between LREE-enriched plumes and arcs. The similarities in lithology, lithogeochemistry, and depositional ages of the rocks in the Boa Vista de Minas Group suggest that it represents a high-grade counterpart to the Pitangui Greenstone Belt. This implies that the tectonic-thermal metamorphic event associated with the final stages of the Minas-Bahia Orogeny extended to the northern limit of the Divinópolis Complex and is more extensive than previously anticipated.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105459"},"PeriodicalIF":1.7,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143592432","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":"Flow-type controls on tributary alluvial fan formation along the Andes (18-34°S)","authors":"Albert Cabré ,&nbsp;Germán Aguilar ,&nbsp;Ferràn Colombo ,&nbsp;José Luis Antinao ,&nbsp;Diego Iturra","doi":"10.1016/j.jsames.2025.105442","DOIUrl":"10.1016/j.jsames.2025.105442","url":null,"abstract":"<div><div>Debris flows, locally known as ‘<em>aluviones</em>’ or ‘<em>huaicos</em>’, in Andean tributary alluvial fans form distinctive facies associations that can be classified into High-density Flows (HdF) and Low-Density Flows (LdF) based on sediment-to-water ratios and transitions from highly dense, viscous flows to more diluted ones. This distinction, based on ground evidence and remotely sensed debris flow identification, establishes the first equivalence between field-based and optical satellite imagery observations using Google Earth. By analysing the activity of tributary alluvial fans over the past 20 years with open-access optical satellite imagery, we provide new insights into fan evolution and the extent to which lateral sediment inputs impact sediment transfer along axial river valleys of the Andes.</div><div>Our observations reveal that large-volume debris flows, typically associated with HdF, contribute to fan expansion and aggradation. In contrast, more diluted flows -ranging from hyperconcentrated to fluvial flows-promote fan destruction through incision of the feeder channel. Fans dominated by LdF facies associations often exhibit incision and progradation, forming new lobes at the fan toe. These lobes are frequently reworked by the main channel due to the limited sediment supply. Whether tributary fan sedimentation and progradation influence the main channel or if sediments are buffered on the fans largely depends on the characteristics of the flows and on the original topography of the fan. Accordingly, classifying debris flow surges into two distinct facies associations (AF1 and AF2, corresponding to HdF and LdF, respectively) enhances our understanding of fan dynamics and their influence on axial valleys at regional scale. This study underscores the importance of sedimentological flows characteristics in governing fan evolution, influencing both fan development across a broad latitudinal range (18-34°S) and sedimentary signal propagation along the Andes Cordillera. Moreover, the findings have significant implications for national debris flow hazard mitigation efforts and aligns with global strategies outlined in the Sendai Framework for Disaster Risk Reduction, promoting resilience and improved risk management in developing regions.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"156 ","pages":"Article 105442"},"PeriodicalIF":1.7,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143551624","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":"Co-occurrence of Prolagostomus Ameghino and Chasicomys Pascual (Caviomorpha, Rodentia) from the late Neogene of the Northwestern Argentine Puna: biostratigraphic and palaeoenvironmental implications","authors":"Juan F. Escamilla ,&nbsp;Silvina A. Contreras ,&nbsp;Adriana M. Candela ,&nbsp;Carlos A. Luna ,&nbsp;Alfredo E. Zurita","doi":"10.1016/j.jsames.2025.105455","DOIUrl":"10.1016/j.jsames.2025.105455","url":null,"abstract":"<div><div>Caviomorpha is a highly diversified clade among the Cenozoic South American mammals, notable for its extensive fossil record and ecological diversity. However, the evolutionary history of the Caviomorpha in the Andean and sub-Andean regions remains poorly understood. The recent discovery of fossils from the Calahoyo locality in the Puna Biogeographic Province (northern Jujuy, Argentina) has provided insights into this gap in our knowledge. The fossils include <em>Chasicomys</em> sp. (Octodontoidea) and <em>Prolagostomus</em> sp. (Chinchillidae) from the lower strata of an innominate unit underlying the Tafna Formation, which represent the northernmost record of these taxa in Argentina. This discovery is significant in that it represents the first documented co-occurrence of these two taxa. An absolute zircon dating of ca. 8 Ma from a tuff located 18 m above the fossiliferous level, in conjunction with biochronologic correlations, indicates a Late Miocene age for this level. This extends the known temporal range of <em>Prolagostomus</em> and enhances the significance of <em>Chasicomys</em> as a stratigraphic indicator for the Tortonian. The phytolith analysis indicates that the environments predominantly comprised grasses (Pooideae and Panicoideae) with herbaceous/woody dicotyledonous elements; with presence of palms in one area and non-phytolith elements such as diatoms and golden algae in the other. This suggests that there were varying moisture levels. These findings are of crucial importance for understanding the late Neogene evolution of the Puna ecosystem.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"157 ","pages":"Article 105455"},"PeriodicalIF":1.7,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637763","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}