Journal of South American Earth Sciences最新文献

{"title":"Size and style of the November 3, 2002 eruption of El Reventador volcano (Ecuador) assessed from tephra studies","authors":"Jean-Luc Le Pennec ,&nbsp;Séverine Delpit ,&nbsp;Silvana Hidalgo ,&nbsp;Daniel Basualto ,&nbsp;Pablo Samaniego ,&nbsp;Daniel Hermitte ,&nbsp;Patricio Ramón","doi":"10.1016/j.jsames.2026.105997","DOIUrl":"10.1016/j.jsames.2026.105997","url":null,"abstract":"<div><div>On November 3, 2002 El Reventador volcano (Ecuador) erupted violently, causing damages near the volcano and intense ash falls in the Interandean Valley. To assess the size and style of the eruption we conducted field work to obtain tephra thickness measurements and samples in the area located ∼50–100 km from source. The thickness data (max. 40 mm) were processed to draw an isopach map that reveals a plume dispersal to the WSW of the volcano. The ash samples underwent grain size distribution (GSD) and componentry analyses, morphometric characterization, bulk and solid density determinations, and chemical analyses. The GSD results show a single mode at 3–4 ϕ in the study region, indicating a finely comminuted tephra. The componentry in the deposits reveals strong density-driven fractionation of dominant poorly to highly vesiculated juvenile ash particles, and of abundant xenolithic grains. The bulk ash density was close to 1017 kg/m³, whilst the solid (powder) density is ∼2640 kg/m³, and the juvenile ash bears the composition of the most differentiated products documented in historical times at El Reventador (silicic andesite: 58-59 wt% SiO₂). The bulk volume of the tephra fall deposit is estimated at 80 × 10⁶ m³, and the total volume with PDC deposits at 135 × 10⁶ m³ (VEI4 range), while the mass-based magnitude and intensity reach 4.2 and 10.8, respectively, in the range of subplinian eruptions. Accordingly, on November 3, 2002 El Reventador volcano released the largest explosive event in the whole North Volcanic Zone of the Andes since more than a century. Also, our study shows the importance of obtaining urgently ground-based data after any unexpected eruption for scenario elaboration, and that there is still room to technically improve the early characterization of such sudden explosive events.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105997"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175034","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":"Devonian metavolcanic rocks in the Rio Puelo section, Patagonian Andes of Chile: possible implications for the eastern limit of Chaitenia and the origin of the Liquiñe Ofqui Fault Zone","authors":"F. Hervé ,&nbsp;C.M. Fanning ,&nbsp;P. Quezada ,&nbsp;P. Castillo ,&nbsp;K. Deckart ,&nbsp;R.J. Pankhurst ,&nbsp;C.W. Rapela ,&nbsp;C. Palape ,&nbsp;M. Zúñiga ,&nbsp;M. Calderón","doi":"10.1016/j.jsames.2026.106001","DOIUrl":"10.1016/j.jsames.2026.106001","url":null,"abstract":"<div><div>U-Pb zircon dating of a finegrained metamorphosed porphyritic siliceous magmatic rock from Rio Puelo (Continental Chiloé; ca.72.0°W/41.7°S) yields a Lower Devonian (ca. 395 Ma) igneous crystallization age. This is broadly similar to ages previously obtained for igneous rocks from the two contrasting Devonian magmatic belts located east and west of the main Andes in this part of Patagonia, namely the Foreland Devonian Domain (FDD) and the Pacific Devonian Domain (PDD). The dated zircon grains have oxygen isotopic ratios, characteristic of the FDD (δ¹⁸O_zircon 6.6 to 9.5‰), and this indicates a westerly extension of the igneous rocks of this domain as far as the NNE trending Liquiñe - Ofqui Fault Zone (LOFZ). Detrital zircon U-Pb ages for a metasedimentary rock from the FDD (Piedra Santa area; ca. 70.4°W/39.2°S) indicate a maximum depositional age of ca. 365 Ma, but it shows Devonian detrital zircon age spectra and O-isotope compositions (δ¹⁸O_zircon 6.5 and 7.9‰) similar to those of metasedimentary units in the PDD south and west of Rio Puelo. It is suggested that the Devonian igneous rocks of the FDD were subject to erosion shortly after their emplacement with much of the eroded material being deposited in the PDD arc after the accretion of Chaitenia. The Liquiñe Ofqui Fault Zone, still active today, lies in the contact area between the FDD and the PDD, suggesting that its location might be inherited from the original suture contact between these two Devonian magmatic belts.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 106001"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385923","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":"Reconstructing volcanic architecture through eruptive style and spatial analysis: Cretaceous rift volcanism in the Alemanía subbasin, Salta, Argentina","authors":"M.F. Quiroga ,&nbsp;M. Arnosio ,&nbsp;E. Bustos ,&nbsp;N. Salado Paz ,&nbsp;R. Becchio ,&nbsp;A. Villagrán ,&nbsp;O. Arenas","doi":"10.1016/j.jsames.2026.105981","DOIUrl":"10.1016/j.jsames.2026.105981","url":null,"abstract":"<div><div>Reconstructing facies architecture in ancient volcano-sedimentary successions is often challenging due to incomplete exposure, deformation, metamorphism, and hydrothermal alteration. The Alemania Subbasin (Salta, Argentina) preserves exceptionally well both sedimentary and volcanic successions, which are exposed as subvolcanic and volcanic units due to tectonic activity. The Cretaceous northwestern basins of Argentina are interpreted as an aborted retroarc rift, comprising interconnected grabens that converge at a triple junction with a central horst (Salta–Jujuy horst). The Alemania Subbasin contains thick sedimentary-volcanic successions of the Salta Group, including the Pirgua, Balbuena, and Santa Bárbara subgroups. The Pirgua Subgroup consists of continental red beds deposited during the syn-rift stage, with volcanic activity primarily recorded by the Las Conchas Basalt (78–77 Ma) in the upper part of the succession (Las Curtiembres Formation). This study focuses on outcrops along Las Conchas Canyon, where both coherent volcanic facies (lava flows, pillow lavas, dykes) and volcaniclastic facies (diatreme breccias, pyroclastic surge deposits, peperites, sediment-infill volcanic breccias, and lahars) interbed with fluvial red beds. Variations in facies architecture reflect contrasting eruptive styles, likely controlled by changes in environmental hydrology and magma–water interaction processes. The Las Conchas Basalt records both hydromagmatic and effusive eruptions. Volcanic architecture reconstruction allowed the identification of facies corresponding to upper and lower diatreme deposits, dykes, and lava flows, associated with peperites and sediment-infill volcanic breccias. Subvolcanic units were likely emplaced in a meandering fluvial paleoenvironment, whereas lava flows advanced across sandy braided fluvial systems under semi-arid conditions. Pillow lavas within lacustrine host rocks (Morales Members) indicate local water bodies sufficient for non-explosive magma–water interactions. Changes in water availability and environmental conditions likely explain the transition from hydromagmatic to effusive eruptive styles, despite the magma remaining basanitic. This study demonstrates that paleoenvironmental and hydrological conditions strongly influenced facies development in monogenetic volcanic fields and provides insights into reconstructing ancient volcano–sedimentary systems in rift-related basins.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105981"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175028","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":"Evolving open-vent activity at Popocatépetl volcano (2019–2024): satellite insights into conduit permeability, the 2023 paroxysmal phase, and the transition in dome-forming behavior","authors":"Francesco Massimetti,&nbsp;Sébastien Valade,&nbsp;Robin Campion","doi":"10.1016/j.jsames.2026.105991","DOIUrl":"10.1016/j.jsames.2026.105991","url":null,"abstract":"<div><div>Popocatépetl, Mexico's most active volcano and one of the world's strongest volcanic SO₂ emitters, poses a major hazard to more than 20 million people. This study presents a comprehensive space-based investigation of its activity from 2019 to 2024, integrating thermal IR, UV gas absorption, radar, and VNIR satellite imagery. We analyzed Volcanic Radiative Power (VRP), SO₂ flux, crater depth, and thermal anomalies to characterize recent eruptive behavior. TROPOMI data reveal three distinct degassing regimes, from ∼1100 t/d in 2019 to ∼3000 t/d after 2023, with a mean of ∼1600 t/d, among the lowest since persistent activity began in 1994. VRP ranged between 0.01 and 1000 MW, declining until mid-2022 and rising before the May–June 2023 explosive phase. Popocatépetl ceased producing its characteristic pancake-shaped lava domes after 2020, marking a transition from dome-building cycles to a new activity regime characterized by small-scale, short-lived extruded lava bodies, with almost no associated morphological change. Variations in the VRP/SO₂ ratio suggest changes in conduit permeability associated with long-term crater deepening, with elevated ratios preceding the 2023 explosions, consistent with reduced gas escape and overpressure buildup. Following the 2023 paroxysm, high degassing decoupled from thermal emissions, indicating renewed magma input and sustained open-vent degassing. Due to limited extrusion, excess degassing and thermal output, calculated as volumetric fluxes responsible for degassing (Q_degas) and radiation (Q_rad), point to shallow magma convection. These findings underscore the importance of multiparametric satellite observations to detect transitions in eruptive style, conduit permeability, and degassing dynamics at open-system volcanoes such as Popocatépetl.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105991"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385827","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":"U–Pb geochronology of REE–Nb–Ta–U–Th minerals in the NW Amazonian Craton: Evidence for two Mesoproterozoic mineralization events","authors":"José Alejandro Franco Victoria ,&nbsp;Amed Bonilla Pérez ,&nbsp;Marc Poujol ,&nbsp;Thomas Cramer ,&nbsp;Carlos Alfonso Zafra Mejía","doi":"10.1016/j.jsames.2026.106004","DOIUrl":"10.1016/j.jsames.2026.106004","url":null,"abstract":"<div><div>Critical-metal mineralization in the NW Amazonian Craton remains poorly constrained in age, limiting our understanding of the timing and tectonomagmatic context of Mesoproterozoic metallogenic processes. To address this gap, we present direct LA–ICP–MS U–Pb geochronology of REE–Nb–Ta–U–Th–bearing accessory minerals from eastern Colombia and southern Venezuela. Heavy-mineral concentrates from the Espina Hills (Guainía, Colombia) and the El Burro–Aguamena area (Venezuela) contain ilmenorutile, monazite, and xenotime associated with quartz–muscovite pegmatitic colluvium. U–Pb data yield crystallization ages of 1394 ± 19 Ma (xenotime), 1395 ± 12 Ma (monazite), and 1345 ± 12 to 1348 ± 15 Ma (ilmenorutile and monazite), defining two discrete Mesoproterozoic mineralization pulses recorded by texturally and compositionally coherent mineral populations. These ages correspond to late-stage alkaline to pegmatitic magmatism coeval with the Parguaza and Matraca rapakivi granites, indicating prolonged anorogenic crustal melting and HFSE–REE enrichment between ∼1.40 and 1.34 Ga.</div><div>Beyond their geochronological significance, the combined mineralogical, chemical, and isotopic signatures provide a robust provenance framework linking detrital heavy-mineral assemblages to concealed felsic–pegmatitic sources in northern Amazonia, thereby contributing to regional metallogenic models and mineral traceability efforts.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 106004"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385836","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":"Eco-hydro-morphological evolution of river basins affected by volcanic eruptions in southern Chile: a conceptual model and a risk management approach","authors":"Valeria Zingaretti ,&nbsp;Rosario Florín ,&nbsp;Bruno Mazzorana ,&nbsp;Andrés Iroumé","doi":"10.1016/j.jsames.2026.105978","DOIUrl":"10.1016/j.jsames.2026.105978","url":null,"abstract":"<div><div>Volcanic eruptions in southern Chile have repeatedly triggered cascading processes that interacted with fluvial dynamics, generating eco-hydrogeomorphological changes at multiple spatial and temporal scales. In recent decades, eruptions of the Complejo Volcanico Puyehue-Cordón Caulle (CVPCC), Chaitén and Calbuco volcanoes in Chile have profoundly altered the morphology and ecological functions of surrounding river basins, promoting long-term destabilisation and adjustment processes. While previous studies have addressed key aspects such as sediment and wood transport, vegetation recovery, and geomorphological change, these analyses often lacked a systemic approach that integrates eco-hydrogeomorphological perspectives to understand why and how processes unfold and interact. In this context, we propose a conceptual model that makes the recovery trajectories of river corridors affected by volcanic eruptions in southern Chile explicit, with Chaitén as a central case study and integrating insights from CVPCC and Calbuco. The model identifies patterns of response and adjustment in fluvial systems, emphasizing the role of biphasic flows, landform evolution, and vegetation dynamics. Based on this, we outline an integrated approach for hydrogeomorphological risk management, highlighting the importance of long-term monitoring, adaptive planning, and proactive measures. This approach moves beyond short-term mitigation, aiming to strengthen preparedness and enhance resilience in volcanic landscapes exposed to recurrent disturbances. Through the systematization of evidence into a transdisciplinary framework, this study delivers one of the first integrative conceptual models for eruption-affected river basins in southern Chile, with direct implications for risk reduction and community resilience.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105978"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385909","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":"ARMADILLO_VolcaNorm: An open-source, macro-enabled VBA for Excel™ spreadsheet for calculation of CIPW norms and IUGS igneous rock classification for volcanic rocks","authors":"John Charles White ,&nbsp;Federico Lucci","doi":"10.1016/j.jsames.2026.106002","DOIUrl":"10.1016/j.jsames.2026.106002","url":null,"abstract":"<div><div>ARMADILLO_VolcaNorm is a versatile, user-friendly, open-source, macro-enabled spreadsheet that can rapidly calculate CIPW normative mineralogy (<em>viz</em>., “a norm”) and classify volcanic rocks following IUGS recommendations entirely within the Microsoft Excel™ environment. The program can process up to 10,000 major-element analyses of volcanic rocks, with the user specifying whether total iron is reported as FeO∗ or Fe₂O₃∗ and selecting one of seven methods of re-partitioning iron (or providing a custom value), including options that incorporate temperature, pressure, redox buffer, and offset. ARMADILLO_VolcaNorm outputs the FeO/FeO∗ ratio for each sample, computes the normative mineralogy, and applies total alkali-silica (TAS) and norm-based criteria for accurate classification. It can also generate customizable TAS diagrams with labeled samples. Unlike previous tools, ARMADILLO_VolcaNorm operates seamlessly within Excel, enabling simple copy-and-paste workflows and enhancing reproducibility and accessibility in igneous petrology.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 106002"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147385921","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":"Apatite thermochronology and geochemistry applied to modern river sediment from the Southern Brasilia Orogen, northeastern São Paulo State/Brazil","authors":"Jaqueline Dickel Bilhar ,&nbsp;Carlos Alberto Tello Sáenz ,&nbsp;Cleber Jose Soares ,&nbsp;Maria Lidia Medeiros Vignol-Lelarge ,&nbsp;David Chew ,&nbsp;Foteini Drakou","doi":"10.1016/j.jsames.2026.105979","DOIUrl":"10.1016/j.jsames.2026.105979","url":null,"abstract":"<div><div>Geo-thermochronology integrated with trace-element geochemistry analysis can provide important information about the exhumation and provenance of modern river sediment (MRS) sources. Here, we present apatite thermochronology (U-Pb and FT dating) and apatite trace element analysis (including the REE) from four samples of MRS from the Rio do Peixe (RP) and one bedrock sample, from the Southern Brasilia Orogen (São Paulo State, Brazil) by laser ablation - inductively coupled - plasma mass spectrometry (LA-ICP-MS). The goal is to obtain information about episodes of crystallization/metamorphism and exhumation of the sediment sources. A total of 358 apatite grains were analysed (310 MRS apatites) for combined LA-ICP-MS U-Pb, AFT and trace element geochemistry data. Mafic I-type granitoids and mafic igneous apatites (IM) predominate in the sediment, followed by low- and medium-grade metamorphic (LM), high-grade metamorphic (HM) and finally ultramafic apatites (UM). The predominance of IM apatites probably reflects the concentration of IM lithologies in the RP headwater region. There was no U-Pb age dispersion between the MRS samples and between different lithologies (using an apatite trace-element geochemistry classifier). This ca. 580 Ma U-Pb age peak records cooling in Southern Brasilia Orogen during the Braziliano/Panafrican Orogenic Cycle. MRS samples present five AFT age populations, with mixed pre-, syn-, and post-Gondwana breakup ages: P1 at ∼50 Ma, P2 at ∼100 Ma, P3 at ∼150 Ma, P4 at ∼200-300 Ma, and P5 at &gt;300 Ma.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105979"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175033","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 window into a middle Eocene mesotrophic mixed siliciclastic-carbonate system from the South American Pacific margin (Paracas Formation, Pisco Basin, Peru)","authors":"Giovanni Coletti ,&nbsp;Luca Mariani ,&nbsp;Elisa Malinverno ,&nbsp;Alberto Vimercati ,&nbsp;Claudio Di Celma ,&nbsp;Alberto Collareta ,&nbsp;Giancarlo Molli ,&nbsp;Giovanni Sarti ,&nbsp;Giovanni Bianucci ,&nbsp;Orangel Aguilera ,&nbsp;Alessandro Cavallo ,&nbsp;Mario Urbina ,&nbsp;Giulia Bosio","doi":"10.1016/j.jsames.2026.105983","DOIUrl":"10.1016/j.jsames.2026.105983","url":null,"abstract":"<div><div>The Paracas Formation of the Pisco Basin (southern Peru) includes the lower Los Choros Member and the upper Yumaque Member and preserves key paleoenvironmental information on the shallow-marine tropical ecosystems of the eastern Pacific in middle Eocene times. This study focuses on five stratigraphic sections and a few minor outcrops of the Los Choros Member exposed in the Ica Desert. Sedimentological observations, X-ray diffraction data, and micropaleontology reveal a vertical transition from coarse-grained, mixed siliciclastic-carbonate bioclastic deposits resting unconformably on the pre-Cenozoic basement, to finer-grained fossiliferous mudstones of the overlying Yumaque Member. Large benthic foraminifera from the Los Choros Member and nannofossils from the base of the overlying Yumaque Member constrain the deposition of the former to around 43 Ma. Skeletal assemblages include both large and small benthic foraminifera along with mollusks, barnacles, red algae, echinoderms and bryozoans, pointing to a warm-temperate to tropical, shallow-marine setting characterized by moderate hydrodynamic energy and mesotrophic conditions. Despite being taxonomically distinct, the carbonate-producing systems of the paleo-Pacific display functional similarities with the coeval Tethys platforms. These systems evolved independently until the Oligocene, when lepidocyclinids expanded into the Tethys, thereby replacing rapidly the indigenous, nummulitid-dominated faunas. The factors behind the evolutionary success and dispersal of the lepidocyclinids are still largely unknown, but the sedimentological and paleoecological features of the Los Choros strata suggest that thermal adaptability played a major role.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105983"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175030","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":"Fossil record and paleogeography of Erythrinidae (Characiformes): new fossil evidence of Paleohoplias from the Solimões Formation","authors":"Bernardo Decat ,&nbsp;Orangel Aguilera ,&nbsp;Rafael Costa da Silva ,&nbsp;Olga Oliveira de Araújo ,&nbsp;Carlos De Gracia ,&nbsp;Ricardo Tadeu Lopes","doi":"10.1016/j.jsames.2026.105957","DOIUrl":"10.1016/j.jsames.2026.105957","url":null,"abstract":"<div><div>We describe †<em>Paleohoplias amazonensis</em> n. sp., a new extinct erythrinid (Characiformes) from the Late Miocene Solimões Formation, Brazil, and integrate this finding within assessment of the fossil record and paleogeography of Neotropical Erythrinidae. The new species, represented by a well-preserved dentary, increase the known diversity of the genus †<em>Paleohoplias</em> in the western Amazonia and complements the only previously described species †<em>Paleohoplias assisbrasiliensis</em>. By combining the know fossil record of Erythrinidae with a regional synthesis of fossil freshwater ichthyofaunas from Pebas, La Victoria, Urumaco, Solimões, and San Gregorio formations, we identify a Late Miocene paleogeographic range expansion of Erythrinidae. Cluster analyses on Jaccard dissimilarities reveal close faunal affinities among cis-Andean basins, supporting the hypothesis of a Proto-Amazonian system that connected the Pebas and Llanos basins before the Andean uplift. Subsequent Miocene-Pleistocene drainage reorganizations and climatic oscillations progressively constrained freshwater distributions, establishing dispersal corridors and barriers that shaped the modern <em>Hoplias</em> complex. Altogether, the new fossil and associated data provide key paleogeographic calibration points for understanding the spatiotemporal evolution of Erythrinidae within Neotropical river systems. This study is a baseline for further time calibrated phylogenies and provide paleontological context for future reassessment of erythrinid paleogeography based on DNA and modern distribution evidence.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"174 ","pages":"Article 105957"},"PeriodicalIF":1.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175096","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}