Journal of South American Earth Sciences最新文献

{"title":"Unveiling the nature of glassy impact spherules by analyzing pristine Chicxulub spherules from Gorgonilla Island","authors":"Hermann D. Bermúdez ,&nbsp;Vivi Vajda ,&nbsp;Kajsa G.V. Sigfridsson Clauss ,&nbsp;Courtney Jean Rundhaug ,&nbsp;Gavin Kenny ,&nbsp;Liliana Bolívar ,&nbsp;Daniela Bermúdez ,&nbsp;Ying Cui","doi":"10.1016/j.jsames.2025.105877","DOIUrl":"10.1016/j.jsames.2025.105877","url":null,"abstract":"<div><div>The Chicxulub impact triggered a massive extinction event marked by the Cretaceous-Paleogene boundary (K-Pg ∼66Ma), ejecting vast amounts of dust, molten, and vaporized materials. While impact spherules are interpreted as products of impactor and target lithologies, their precise composition and distribution remain insufficiently constrained. Although previous studies restrict impactor contamination to the condensed spherules from the fireball layer and the K-Pg boundary clay, here we show asteroid contribution to the composition of large spherules from the base of the K-Pg bed. Despite those spherules displaying an apparent immiscible bimodal composition of yellow (Ca-rich) and black (Si-rich) glasses, novel nano-resolution analyses demonstrate enrichment of elements derived from the impactor. By analyzing pristine spherules from the normally-graded sequence of Gorgonilla Island K-Pg site, our results show the presence of metals and platinum group elements (PGEs) in glasses and vesicles within large molten spherules. Furthermore, needle-like and cubic-shaped nanostructures co-localizing Pt, Co, Ni, and Pb, and Cu, Os, and Zn, may represent the first evidence of quasicrystals (quasi-periodic solids, not found in terrestrial rocks, with symmetries forbidden for crystals) in Chicxulub-derived deposits. Those nanostructures challenge the definitions of microtektites and microkrystites, suggesting these classifications are misleading. We recommend abandoning such terminology, preserving the generic term \"impact spherules,\" irrespective of composition, morphology, or size. Our findings contribute to refining the classification and interpretation of impact spherules, advancing our understanding of the processes underlying hypervelocity impacts. Moreover, these insights may hold relevance not only for terrestrial impacts but also for analogous extraterrestrial contexts.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105877"},"PeriodicalIF":1.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571429","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":"Interseismic strain accumulation along the Chilean segment of the Magallanes – Fagnano fault zone recorded by continuous GNSS","authors":"Francisco Delgado ,&nbsp;Juan Carlos Báez ,&nbsp;Pablo León-Ibáñez","doi":"10.1016/j.jsames.2025.105889","DOIUrl":"10.1016/j.jsames.2025.105889","url":null,"abstract":"<div><div>We present the first evidence of interseismic strain accumulation along the Chilean segment of the Magallanes Fagnano Fault Zone, the plate boundary between the Scotia and South America plates. We use a network of seven continuous GNSS stations, including two deployed within <span><math><mo>∼</mo></math></span> 8 km from the fault trace. Despite the low spatial resolution of the network, the data record a variation of <span><math><mo>∼</mo></math></span> 6 mm/yr in the eastward velocity across a <span><math><mo>∼</mo></math></span> 100 km long transect. This is compatible with the presence of a likely segmented, locked strike-slip fault. The velocities can be modeled by an infinitely long screw dislocation parallel to the mapped fault trace, with fault-parallel velocity of 5.48 mm/yr and locking depth of 6.45 km. The geodetic fault velocity is similar to that measured elsewhere by previous studies with denser campaign GNSS in Argentina and with post-glacial fault slip rate derived from geomorphic offsets. This suggests a consistency between the long-term fault slip that records the cumulative deformation over many earthquake cycles and the nearly instantaneous strain accumulation. The time series do not show clear evidence for aseismic release of energy such as slow-slip events, fault creep, or other processes such as glacial isostatic adjustment. We speculate that the strain accumulation extends towards the fault segments that are located beneath the fjords in the region.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105889"},"PeriodicalIF":1.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145618069","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":"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,&nbsp;Cláudia Regina Passarelli,&nbsp;Antonio Roberto Saad,&nbsp;Paulo Roberto dos Santos,&nbsp;Miguel Ângelo Stipp Basei,&nbsp;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_(t) values ranging from −6 to +4, and crustal model ages (T_DM^c) 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":"2026-01-01","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}

{"title":"Validation of SMAP, SMOS, and ESA CCI SM soil moisture products in a seasonally dry tropical forest","authors":"Cloves Vilas Boas dos Santos ,&nbsp;Josiclêda Domiciano Galvíncio ,&nbsp;Rodrigo de Queiroga Miranda ,&nbsp;Herica Fernanda de Sousa Carvalho ,&nbsp;Alzira Gabrielle Soares Saraiva Souza ,&nbsp;Inajá Francisco de Sousa ,&nbsp;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 m³ m⁻³, MAE = 0.01 m³ m⁻³, 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 m³ m⁻³, MAE = 0.01 m³ m⁻³, 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":"2026-01-01","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}

{"title":"Neoproterozoic magmatic arcs of the Dom Feliciano Belt, southern Brazil","authors":"Ruy Paulo Philipp ,&nbsp;Edinei Koester ,&nbsp;Miguel Angelo Stipp Basei ,&nbsp;Rodrigo Fabiano Cruz ,&nbsp;Vinicius Germano Hilgert ,&nbsp;Daniel Triboli Vieira ,&nbsp;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":"2026-01-01","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}

{"title":"Carbon cycle dynamics in the subtropical South Atlantic: orbital pacing and regional modulation over the last 772 kyr","authors":"José, Renato Derntl,&nbsp;Karen, Badaraco Costa,&nbsp;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 (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.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105848"},"PeriodicalIF":1.5,"publicationDate":"2026-01-01","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}

{"title":"Can hydrological loads modulate intraplate seismicity in the Parecis Basin, Brazil?","authors":"Yellinson de M. Almeida ,&nbsp;Henry Montecino C. ,&nbsp;George Sand França ,&nbsp;Aharon S. Cuevas","doi":"10.1016/j.jsames.2025.105878","DOIUrl":"10.1016/j.jsames.2025.105878","url":null,"abstract":"<div><div>The processes responsible for triggering seismicity within intraplate regions remain incompletely understood. One proposed driver of such seismicity is the seasonal variation in hydrological loads, which may influence both the frequency and magnitude of earthquakes in these areas. In Brazil, the Parecis Basin has exhibited persistent seismic activity over recent years, with sporadic occurrences of earthquakes of considerable magnitude. In this study, we analyzed a seismic catalogue spanning from 2014 to 2022 to investigate potential correlations between seismicity and hydrological cycle in this region. We used geodetic data—including GPS positioning and satellite gravimetry—as well as precipitation records. The correlations between these observations and seismicity averaged −0.64 (TWSA-GRACE), 0.61 (VD-GPS), and −0.53 (precipitation), indicating that seismicity tends to increase in the Parecis Basin and adjacent areas at the end of the dry season. Temporal analysis of phase lags between hydrological indicators and seismic events suggests that the modulation of seismicity is driven primarily by the diffusion of pore pressure in the upper crust due to variations in hydrological loading.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105878"},"PeriodicalIF":1.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571430","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":"Historical activity (1522–2025) of the Masaya volcano in Nicaragua and characterization of Pelé's hair and tears from the 2016 eruption","authors":"Guillermo E. Alvarado-Induni ,&nbsp;Hugo Delgado-Granados ,&nbsp;Martha Navarro-Collado ,&nbsp;Arnoldo Castillo-Ferrufino ,&nbsp;María Martínez-Cruz ,&nbsp;Ariadna Calderón ,&nbsp;Carlos Linares-López ,&nbsp;Reinaldo Pereira-Reyes ,&nbsp;Alexis Debut ,&nbsp;Virginia Tenorio ,&nbsp;Theofilos Toulkeridis","doi":"10.1016/j.jsames.2025.105856","DOIUrl":"10.1016/j.jsames.2025.105856","url":null,"abstract":"<div><div>The eruptive history of the Masaya Volcano in Nicaragua is evaluated for the last five centuries. Historically, this volcano has been characterized by the presence of incandescence in its active crater, with the formation of scoria cones and intra-crater lava flows. These features have been accompanied by small strombolian eruptions, by the magnificence of its well-developed lava lakes with occasional pahoehoe lava flows due to overflow. Furthermore, this volcano experienced also rare, unexpected most likely phreatomagmatic explosions, besides persistent acid clouds and rain. One of its most notable pyroclastic products from its recent reactivation in 2015–2017 is the presence of sideromelanic glasses in the form of Pele's hair and tears. The 2016 samples appear in various shapes, reflecting a basaltic composition inherited from the compositions of previous lava lakes of Masaya. They exhibit a loss of alkali and silicification on their surface as a likely result of direct interaction between magmatic acid gases and juvenile tephra. Pele's hairs display solid glass cylinders with conchoidal fracture, vesicles, while in some cases they exhibit capillary-like tubes or demonstrate inflated portions. These exhibits numerous modifications, including elongated shapes (railway rail, ropes or spermatozoon-like forms), whereas the most contorted shapes may range from wide forms (bent, horseshoes, rings or earrings) to more complex forms (knots, curly or frizzy hair). Complementarily, Pele's tears are characterized by their sphericity, roundness and aspect ratio in small spherical to oval pyroclasts. Their sizes vary from few 3–6 μm to several mm of diameter, while their surfaces are generally rough. The 2016 tephra has S-depleted signature, and a low S/F molar ratio being the fluorine and chlorine the dominant species suggesting a shallow magmatic source. Worldwide, Masaya appears to be one of the few volcanoes displaying a volcanic hazard due to a wide and voluminous distribution of Pele's hair, being a threat to animals and humans alike, hence its unique character.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"169 ","pages":"Article 105856"},"PeriodicalIF":1.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145521146","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 geology and geophysical constraints of the central-north part of the Sierra de Bonilla, Southern Precordillera, Argentina","authors":"María Victoria Sánchez ,&nbsp;Juan Pablo Ariza ,&nbsp;Federico Lince Klinger ,&nbsp;Florencia L. Boedo ,&nbsp;Mario Giménez ,&nbsp;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":"2026-01-01","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}

{"title":"Storm-dominated coastal dynamics in the early Ediacaran record of Argentina","authors":"C. Ferreyra ,&nbsp;B. Christofoletti ,&nbsp;V. Penzo ,&nbsp;G.C. Antunes ,&nbsp;L.V. Warren ,&nbsp;M.J. Arrouy ,&nbsp;D.G. Poiré ,&nbsp;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":"2026-01-01","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}