Journal of South American Earth Sciences最新文献

{"title":"New findings of pseudotachylytes and their paleoseismic significance, Sierras Pampeanas of San Juan, Argentina","authors":"Gladis N. Palacio Balderramo ,&nbsp;Brígida Castro de Machuca ,&nbsp;Ana C. Mugas Lobos ,&nbsp;Gustavo F. Ortíz ,&nbsp;Gimena M. Bazán ,&nbsp;Cristian E. Robledo","doi":"10.1016/j.jsames.2026.105956","DOIUrl":"10.1016/j.jsames.2026.105956","url":null,"abstract":"<div><div>In this contribution, the first occurrence of pseudotachylyte veins in the crystalline basement of the Sierras Pampeanas of San Juan province, Argentina, is presented.</div><div>The Pan de Azúcar and El Retamo pseudotachylyte veins were found closely related to the NNW-SSE trending Valle Fértil and Portezuelos fault zones, two major ductile-brittle shear zones that were tectonically active since the early Paleozoic.</div><div>Macro- and microstructures observed in both pseudotachylytes suggest that they are the product of rapid cooling of silicate melts along paleoseismic zones during faulting. This inference is supported by the presence of distinctive features like intrusive margins, flow banding and melt-corroded rims in clasts. Acicular and globular microlites, as much as lesser quantities of spherulites, were identified in the matrix of these rocks are considered as a product of direct crystallization from the melt. The presence of vesicles and amygdules indicates a possible formation depth of less than 7 km.</div><div>The chemical composition of pseudotachylyte veins closely resembles that of their host rocks, greenschist facies mylonitic rocks and mylonitized granitoid rocks, indicating that they were formed by frictional melting.</div><div>The pseudotachylytes described from the Pan de Azúcar and El Retamo fault zones were found occurring in veins, which is interpreted as an “in situ” origin. These pseudotachylytes were formed long after host rocks mylonitization. Well preserved microstructures and absence of subsequent overprinting suggest that they were formed in the late stages of faulting.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"173 ","pages":"Article 105956"},"PeriodicalIF":1.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146039671","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":"Insights on northeastern South America tectonics from local event tomography","authors":"Mariano S. Arnaiz-Rodríguez ,&nbsp;Noel Crasto ,&nbsp;Ana Jaramillo ,&nbsp;Ivan Koulakov ,&nbsp;Ana K. Sánchez-Gamboa ,&nbsp;Franck A. Audemard ,&nbsp;Carlos E. Reinoza ,&nbsp;Michael Schmitz","doi":"10.1016/j.jsames.2025.105936","DOIUrl":"10.1016/j.jsames.2025.105936","url":null,"abstract":"<div><div>We present results from local earthquake tomography in northeastern Venezuela, where the Caribbean and South American plates meet. The region, dominated by strike-slip faulting, subduction and inhabited by the Paria Seismic Cluster, offers a unique setting for studying the mechanisms of lithospheric tearing, Subduction-Transform Edge Propagator structures and seismic cluster formation. To perform the tomography, we use a compilation of data, including: the ISC catalog, the database of the University of the West Indies, and the data collected by the temporary array of the BOLIVAR (Broadband Ocean-Land Investigation of Venezuela and the Antilles Arc Region) Project. The combined and revised dataset was composed of 286 stations, 4384 events, 70891 P-wave arrivals and 42532 S-wave arrivals. In our results, the Paria Seismic Cluster appears as a weak region (P-wave low velocity zone) where the lithosphere beneath the active strike-slip system and the subduction slab meet. Hence, the lithosphere tears in response to the dominant shear stress aided by the slab. Furthermore, the cluster appears to be a superposition of the seismicity derived from this process and that of the subducted slab. Crustal-scale high velocities in the Paria Peninsula, associated with the intrusive bodies documented in the area are indicative of subduction-related volcanism active beneath the continent from the Late Miocene to Early Pliocene. Furthermore, we image a high-velocity and seismically active zone beneath Trinidad, which is interpreted as a piece of the Atlantic slab that was torn before subducting underneath the South American lithosphere. Finally, we identify several magmatic chambers beneath the southern Lesser Antilles Arc, as well as an LVZ that we interpret as an upwelling that feeds the volcanism.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105936"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927671","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":"Interannual variations in the araruama hypersaline system: Implications for the sedimentological and hydrological characteristics of brejo do espinho lagoon (Rio de Janeiro, Brazil)","authors":"Amanda Vilar ,&nbsp;Pierre Belart ,&nbsp;Joalice de Oliveira Mendonça ,&nbsp;Thiago Carelli ,&nbsp;Lazaro Laut","doi":"10.1016/j.jsames.2025.105939","DOIUrl":"10.1016/j.jsames.2025.105939","url":null,"abstract":"<div><div>This study aims to utilize a multiproxy approach, incorporating physical-chemical parameters, sedimentological, and climate data, to evaluate the trophic status and environmental sediment characteristics of Brejo do Espinho Lagoon during the winter (July 2022) and summer (January 2023). The results revealed significant seasonal and spatial variations, with summer showing lower salinity and higher values for water temperature, total dissolved solids (TDS), and total organic carbon (TOC), indicating a higher inflow of rainfall periods and an increase in primary productivity. In contrast, the BE winter conditions were characterized by higher salinity due to lower precipitation and intensified evaporation. The predominance of fine sediments and high TOC contents in both analysed periods were related to the presence of microbial mats and suggest redox conditions at the bottom. Statistical analyses confirmed that seasonality is a key factor in modulating hydrological and sedimentological dynamics, directly influencing the stability of the different four lagoonal sectors. Sector 4 stood out as the most ecologically stable, while Sectors 2 and 3 exhibited higher seasonal variability. The study emphasizes the lagoon system's sensibility to changes in the hydrological regime, providing essential baseline data to support long-term monitoring and conservation strategies, particularly in the context of ongoing climate change.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105939"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927672","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":"Hydrogeological suitability of Coahuila, Northeast Mexico: An integrated bibliometric, GIS, and water quality assessment","authors":"Ramón Yosvanis Batista Cruz ,&nbsp;Yuri Almaguer Carmenates ,&nbsp;José Alberto Batista Rodríguez ,&nbsp;Felipe de Jesús López Saucedo ,&nbsp;Yalina Montecelos Zamora ,&nbsp;Brenda Margarita Salas Ramos ,&nbsp;Aylin Karel Ibarra Torres ,&nbsp;Frida García Robles ,&nbsp;Luis Eutiquio Canales Gutiérrez","doi":"10.1016/j.jsames.2025.105919","DOIUrl":"10.1016/j.jsames.2025.105919","url":null,"abstract":"<div><div>The hydrogeological potential of Coahuila, Northeast Mexico, is evaluated through an integrated approach that combines cartographic datasets, bibliometric analysis, and a GIS-based assessment of 1912 groundwater points distributed across 28 aquifers. Beyond synthesizing existing regional knowledge, this study introduces a comprehensive methodological framework that links geological, hydrological, and socio-economic dimensions through 18 thematic GIS layers, offering a spatially explicit understanding of the key factors controlling groundwater availability and quality. The bibliometric evaluation also provides the first systematic diagnosis of water-related scientific production in Coahuila, revealing a significant disconnect between local research output and the state's critical water-management challenges. The results indicate that extensive carbonate formations, enhanced by karst processes (e.g., the Cupido, Aurora, Glen Rose, and Edwards formations), constitute the most productive aquifer units, while stratigraphic heterogeneity and local tectonics exert strong controls on permeability, compartmentalization, and groundwater flow. Geomorphological and hydrological conditions further shape the distribution of wells: nearly three-quarters are concentrated in plains and piedmont slopes; whereas, mountain ranges function as primary recharge zones in an arid to semi-arid climate. Hydrological indices, including the Topographic Wetness Index and catchment coefficients, refine the interpretation of recharge-discharge dynamics and explain the high well densities found in lowland basins, which are more vulnerable to salinity and sulfate enrichment. Socio-economic drivers, such as accessibility and population density, also influence drilling patterns. However, groundwater quality remains a major constraint, with widespread salinity and excessive sulfate and heavy-metal contamination being particularly associated with the evaporitic La Virgen Formation (and other hydrogeologically unfavorable lithologies), frequently compromising water suitability. Overall, this study provides a novel, integrated framework that strengthens the scientific basis for groundwater evaluation and offers actionable insights to support more-informed and sustainable water-resource management in Coahuila.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105919"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145847573","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":"Paleoenvironmental and paleoclimatic reconstruction of the Lagoa Grande das queimadas archaeological site, Piauí, Brazil","authors":"Roberta Maciel Pacheco Valente ,&nbsp;Heloisa Helena Gomes Coe ,&nbsp;Karina Ferreira Chueng ,&nbsp;Aline Gonçalves de Freitas ,&nbsp;David Oldack Barcelos Ferreira Machado ,&nbsp;Kita Chaves Damasio Macario ,&nbsp;Marcelo Alves Ribeiro ,&nbsp;José Sebastián Carrión García","doi":"10.1016/j.jsames.2026.105949","DOIUrl":"10.1016/j.jsames.2026.105949","url":null,"abstract":"<div><div>The area of this study is the Lagoa Grande das Queimadas archaeological site, located in the southwest of the state of Piauí, in the semi-arid region of Northeast Brazil, a region that is globally recognized for its archaeological and paleontological heritage. The use of biogenic silica (especially phytoliths) as proxies for paleoenvironmental reconstruction aimed to evaluate the paleoenvironment of ancient human occupations. The phytolith assemblages recovered from the sediment record of the Lagoa Grande das Queimadas archaeological site are predominantly composed of Poaceae morphotypes, mainly<span>Blocky, Bulliform flabellate, Acute bulbosus</span>, and <span>Elongate</span>, with a reduced presence of woody dicotyledons (<span>Spheroid ornate</span>). Arecaceae phytoliths (<span>Spheroid echinate</span>) are also observed throughout the profile, increasing from the oldest to the most recent sample, along with fragments of sponge megascleres and microcharcoals. The results revealed that this region experienced climatic variations during the Greenlandian to Meghalayan, as demonstrated by the phytolith and aquatic bioindicator (sponge spicules and diatom frustules) records. The analyses indicate that between 12,908–12,478 and 4420–4233 cal yrs BP, the temperature and humidity increased progressively, followed by a transition from a more humid climate than at present to drier conditions starting from 4420–4233 cal yrs BP. The qualitative and quantitative results of the phytolith analyses, associated with other proxies studied at this site, contributed to constructing information about the archaeological site and its insertion into the landscape, in addition to understanding the mobility and subsistence models of past human groups during the Holocene in the interior regions of Northeast Brazil.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105949"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979089","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":"The Mesoarchean Algodoeiro Metagranite: a new piece in the Araçuaí Orogen basement inliers puzzle","authors":"Geysianne Morais ,&nbsp;Matheus Kuchenbecker ,&nbsp;Danilo Barbuena ,&nbsp;Lucas Almeida de Souza ,&nbsp;Hugo Marques Ascendino Teixeira ,&nbsp;Lucília Aparecida Ramos de Oliveira","doi":"10.1016/j.jsames.2026.105955","DOIUrl":"10.1016/j.jsames.2026.105955","url":null,"abstract":"<div><div>The Orosirian São Francisco-Congo paleocontinent (SFCP) was one of the crustal segments involved in the Neoproterozoic-Early Paleozoic assembly of the Gondwana supercontinent. During this collisional event, its margins were reworked and fragmented, becoming preserved as basement inliers within the Brasiliano-Pan-African orogenic system. Despite its key role in understanding the processes responsible for the formation of Earth's earliest continental masses, the tectonic evolution and true extent of the SFCP remain poorly constrained. Within the Neoproterozoic Araçuaí Orogen there are several basement inliers, whose Archean and Paleoproterozoic rocks have been valuable to reconstructing SFCP. Here we report the discovery of a small basement inlier in the Southern Espinhaço Range, western domain of the Araçuaí Orogen. Based on integrated field observations, petrography, whole-rock geochemistry and U-Pb zircon geochronology, we characterize the rocks exposed in this inlier and discuss their regional significance. This inlier corresponds to a tectonic slice in which a Mesoarchean (ca. 2.87 Ga) metagranite - herein referred to as the Algodoeiro Metagranite - thrust over the metasedimentary rocks of the Espinhaço Supergroup. The Algodoeiro Metagranite consists of leucocratic, peraluminous, magnesian calc-alkaline metagranites that display moderately to strongly fractionated REE patterns with marked negative Eu anomalies. Petrographic and geochemical similarities, particularly REE slopes and multi-element patterns, combined with geochronological constraints, link these rocks to the gneisses of the Guanhães Complex, exposed in the Guanhães basement inlier, further east. Deformation and metamorphism recorded in the Algodoeiro Metagranite are interpreted as syn-to post-collisional in the context of the Brasiliano-Pan-African orogeny. Taken together, the data indicate that the Algodoeiro Metagranite represents a fragment of the SFCP tectonically reworked within the Araçuaí Orogen during the assembly of West Gondwana. This newly identified inlier therefore adds an important piece to the ongoing efforts to refining the tectonic evolution of eastern South America.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105955"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145979090","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 Santacrucian record of Acarechimys minutus (Octodontoidea) from Laguna del Laja (Cura-Mallín Formation, Chile; late Early Miocene) and its biogeographic implications","authors":"Andrés Solórzano ,&nbsp;Alfonso Encinas ,&nbsp;Mónica Núñez-Flores ,&nbsp;Gabriel Carrasco ,&nbsp;Karina Buldrini ,&nbsp;Jorge Campos-Medina ,&nbsp;René Bobe","doi":"10.1016/j.jsames.2025.105938","DOIUrl":"10.1016/j.jsames.2025.105938","url":null,"abstract":"<div><div>The fossil record of pre-Quaternary continental mammals from Chile remains less well-documented than that of neighboring Argentina and Bolivia. Among the most promising successions is the Miocene Cura-Mallín Formation at Laguna del Laja (37.5°S), which preserves diverse mammalian assemblages spanning nearly 10 million years. One of the rodents previously reported from this locality is <em>Acarechimys</em>, a small octodontoid widely documented in Late Oligocene to Late Miocene continental deposits of South America. However, records from Laguna del Laja were based exclusively on fragmentary and undescribed material, leaving their taxonomic identity uncertain. Here, we describe a Santacrucian (late Early Miocene) occurrence of a caviomorph rodent from Laguna del Laja, represented by a partial mandible preserving m1–m3 and a fragment of the dp4. Dental traits, including a laterally compressed lower incisor and a developed posterior arm of the metaconid, support referral to <em>Acarechimys minutus</em>. This well-dated record provides a stratigraphically constrained occurrence of the species in south-central Chile and narrows the geographic gap between Chilean localities of Chucal in the north and Aysén in the south. The new evidence supports the hypothesis that the Laguna del Laja assemblage was not fully endemic, but rather integrated into the broader Santacrucian biogeographic continuum, reinforcing its value as a key reference point for Neogene faunal and biogeographic studies in the south-central Andes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105938"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886268","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":"Structural control and deformational evolution of the São Francisco gold deposit, Borborema Province (NE Brazil)","authors":"Harrizon Lima de Almeida ,&nbsp;Jucieny Sousa de Moura Barros","doi":"10.1016/j.jsames.2025.105934","DOIUrl":"10.1016/j.jsames.2025.105934","url":null,"abstract":"<div><div>The gold mineralizations of the Borborema Province are structurally controlled and hosted in amphibolite facies metamorphic rock sequences. These gold mineralizations are closely related to the Brasiliano/Neoproterozoic orogeny and classified as orogenic gold deposits. The São Francisco gold deposit (SFGD), located in the Rio Grande do Norte Domain, Borborema Province, has emerged as the most significant gold mine in the region. The SFGD is hosted in biotite schists of the Seridó belt and consists of a planar and elongated, SW-NE-oriented ore shoot spatially associated with F₃ antiform fold. The gold occurs both within quartz veins and disseminated in the mica schist, in paragenetic association with pyrite, pyrrhotite, arsenopyrite, and galena. A structural mapping conducted in this study shows that the SFGD occurs in the hinge zone of a F₃ fold, which is primarily controlled by an intersection lineation developed during the D₃ deformation event. A 3D-dimensional strain analysis was conducted on the mica schists of the area, encompassing different segments of the mineralization-hosting structure. The deformation in the hinge zone and in the limbs of the fold was dominated by constriction strain and flattening strain, respectively. It is proposed that the emplacement and occurrence of the SFGD resulted from the increase in structural permeability in the hinge zone, which, combined with a localized constriction strain regime, enabled the pipe-like channelling of a high volume of hydrothermal fluids. The SFGD represents an alternative model for the formation of saddle reef-type ore shoots in F₃ antiform folds hosted in the Seridó belt, Borborema Province.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105934"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927675","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":"Anatectic pegmatites and partial melting evolution in the Paleoproterozoic basement of the Tandilia Belt, Río de la Plata Craton: Insights from Barker and Balcarce regions (Argentina)","authors":"Federico J. Saponara ,&nbsp;Maria F. Lajoinie ,&nbsp;Mabel E. Lanfranchini ,&nbsp;Christopher J. Spencer ,&nbsp;Belén Marone","doi":"10.1016/j.jsames.2025.105929","DOIUrl":"10.1016/j.jsames.2025.105929","url":null,"abstract":"<div><div>This study looks at the origin and development of anatectic pegmatites in the Paleoproterozoic basement of the Tandilia Belt (TB), Río de la Plata Craton, Argentina. It combines new field observations with petrography, whole-rock geochemistry, and stable isotope (δ¹⁸O) data from the Barker and Balcarce regions. The pegmatites, which have granitic and slightly peralkaline compositions, formed mainly during the post-collisional stage from 2026 to 1948 Ma. This occurred under an extensional regime linked to asthenospheric upwelling and they represent the final products of partial melting of metasedimentary and metaigneous rocks through dehydration and fluid-flux melting processes. Field observations show both concordant and discordant intrusions into gneiss, migmatite, amphibolite, granulite, marble, and skarn, which are controlled by tectonic domains and existing structures. Petrographic features include bimodal grain-size distributions, perthitic microcline, heavily sericitized plagioclase, poikilitic and myrmekitic textures, and abundant tourmaline and garnet. These features reflect crystallization from volatile-rich, evolved melts. Geochemical data indicate enrichment in SiO₂, K₂O, and total alkalis. They also show high levels of LILE (Rb, Th, U), a decrease in HFSE (Nb, Zr, Y), and REE patterns marked by LREE/HREE fractionation and varying Eu anomalies. δ¹⁸O values range from +6.5 ‰ to +11.3 ‰, supporting a crustal origin with different degrees of fluid interaction. Higher values in Barker suggest more assimilation from the upper-middle crust, while lower values in Balcarce indicate a stronger influence from mafic lithology and fluid participation. These combined results suggest that the TB pegmatites reflect the late-stage evolution of Paleoproterozoic anatectic magmas. They link the formation to crustal recycling processes and the merging of the Atlantica supercontinent during the 2.2–1.8 Ga interval.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105929"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886267","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":"Degassing-driven seismicity and deformation: Evidence from the Cretaceous Alto Paranaíba Igneous Province, southeastern Brazil","authors":"Lucca Martins Franco ,&nbsp;Miguel Tupinambá ,&nbsp;Emanuele Francesco La Terra ,&nbsp;Liliane Paiva Panetto ,&nbsp;Rogério Guitarrari Azzone","doi":"10.1016/j.jsames.2025.105935","DOIUrl":"10.1016/j.jsames.2025.105935","url":null,"abstract":"<div><div>Here, we provide some structural and mineralogical evidence about what happens below a volcanic field during precursor seismic events. Based on outcrops and borehole material, we analyzed volcanic-related structures within the Cretaceous volcanic sequence of the Alto Paranaíba Igneous Province and the underlying Areado Group sandstones in southeastern Brazil, focusing on the role of magmatic volatiles and magmatic fluid circulation. Structural, petrographic, and geochemical data indicate that magma ascent through subvertical conduits generated overpressure conditions, promoting carbonate-rich hydrothermal activity and widespread deformation. The resulting structural assemblage includes normal faults, deformation bands, localized folding, subhorizontal creeping faults, and soft-sediment deformation structures, particularly concentrated at sandstone–volcanic contacts. Geological profiles highlight the mechanical and hydraulic interaction between alkaline rocks and their sedimentary host. Overall, the results indicate that volatile exsolution during magma ascent was a key driver of fluid-assisted brittle deformation and induced seismicity, exerting first-order control on fault development, sediment destabilization, and hydrothermal alteration.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105935"},"PeriodicalIF":1.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886269","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}