Journal of South American Earth Sciences最新文献

{"title":"Multiscale structural analysis of the Palmital shear zone: A possible suture between Luís Alves Microplate and Paranaguá Terrane, Southern Brazil","authors":"Luís Felipe Machado da Costa ,&nbsp;Renata da Silva Schmitt ,&nbsp;Natasha Stanton ,&nbsp;Leonardo Fadel Cury","doi":"10.1016/j.jsames.2024.105307","DOIUrl":"10.1016/j.jsames.2024.105307","url":null,"abstract":"<div><div>The Palmital Shear Zone, located in the southern Ribeira Orogen, is a NW-SE oriented crustal-scale shear zone that marks the tectonic boundary between two contrasting geological terranes: the Luís Alves Microplate (LAM) to the west and the Paranaguá Terrane (PT) to the east. This study aims to characterize the Palmital SZ through multi-scale structural analysis and geophysical data, to elucidate its tectonic evolution during the amalgamation of the southwestern Gondwana continent. The Palmital SZ is identified by contrasting anomalies between the adjacent geological terranes. The PT is characterized by negative magnetic anomalies, while the LAM exhibits positive magnetic anomalies. Towards the offshore, this magnetic signature contrast extends into the shallow portion of the Brazilian continental margin. The study area presents mafic granulites and type-A granites from the LAM, and ortho- and paragneisses basement intruded by syn-collisional granites belonging to the PT. The tectonic fabric of the PT is characterized by a gneissic foliation (S₁) trending NE-SW and a mylonitic foliation (S₂). The S₂ exhibits proto-to ultra-mylonitic fabrics, trending NNW-SSE with subvertical dip and two stretching lineation orientations: the southern domain displays sub-horizontal plunge, while the central-northern domain, low to moderate plunge to NNE. Microstructural analysis of the mylonitic foliation (S₂) indicates deformation conditions of low temperature (≤450 °C), equivalent to greenschist facies, transitioning from ductile to ductile-brittle regime. Kinematic criteria such as S-C shear bands, quartz oblique foliation, asymmetric feldspar porphyroclasts and mica fish, document sinistral kinematics of the Palmital SZ. Structural, geological and geophysical evidences suggest that the Palmital SZ originated and evolved as a suture juxtaposing latterally the PT Neoproterozoic units with the Paleoproterozoic units of the LAM during the Brasiliano Orogeny. The Palmital SZ progressed from a transpressional deformation to transtensional deformation phase, registering an oblique continental collision.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105307"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143180776","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 calderas field of northern Chile (Atacama region): Eruptive mechanisms and structural control in the latest Cretaceous to Eocene Andean magmatic arc","authors":"Natalia Rodríguez ,&nbsp;Paulina Fuentes ,&nbsp;Eugenio Aragón ,&nbsp;Mackarena Lillo ,&nbsp;Carlos Fernández ,&nbsp;Juan Díaz-Alvarado","doi":"10.1016/j.jsames.2024.105199","DOIUrl":"10.1016/j.jsames.2024.105199","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Thick volcanic and volcano-sedimentary deposits represent Late Cretaceous to Eocene arc magmatism in the Copiapó pre-cordillera (Chile at∼26° S), being the result of the activity of large caldera edifices. This volcanic caldera complex preserves typical features of the evolution of collapse-resurgent caldera systems and evidence for the interaction of local fractures related to collapse processes with large regional structures.&lt;/div&gt;&lt;div&gt;This study presents a stratigraphical, structural and geochemical characterization of the Carrizalillo megacaldera, a huge, 60 km-long and 30 km-wide mega-structure, and its nested calderas, which represent the resurgence of magmatism after the collapse of the main plutonic-volcanic system. The formation and evolution of the Carrizalillo megacaldera and its nested calderas can be related to four well-defined stages of caldera evolution: pre-collapse, collapse, resurgence, and post-collapse. These stages are structurally arranged and influenced by segments of the La Ternera Fault system (in the eastern part) and sub-annular fractures. The pre-collapse stage is characterized by the development of sub-annular fractures in the basement rocks. Subsequently, the initial collapse stage is characterized by the deposition of pyroclastic density currents and fallout deposits, marked by continuous, massive, and/or graded lapilli-tuffs interbedded with thin tuff layers. This was followed by a vast effusive volcanism, which resulted in the deposition of significant volumes of material in the eastern part of the megastructure. Sedimentary deposits and erosional unconformities represent episodic volcanic quiescence. The main collapse stage of the Carrizalillo megacaldera is represented by a high volume extrusion of magma forming homogeneous rhyolitic ignimbrites and lavas. Their arrangement, slightly dipping inward, suggests the progressive subsidence of the roof of the magma chamber during the caldera collapse. Subsequently, the magmatic reservoir was reactivated after the extrusion of the latest ignimbrite deposits of the Carrizalillo megacaldera, resulting in smaller, 10 km-in-diameter nested calderas, aligned along the trace of the La Ternera fault system, to the east of the primary mega-structure. According to the arrangement of volcanic breccias and ignimbrites close to the highly dipping ring fractures of these nested calderas, a more energetic collapse occurred during the first stages of their evolution, followed by the deposition of ignimbrite plateaus. The post-collapse stage corresponds to a period of quiescence, which favored erosion and the accumulation of intra-caldera lacustrine deposits, volcanic edifices formed within the caldera with the emplacement of post-collapse lavas.&lt;/div&gt;&lt;div&gt;Preliminary geochemical results point to low-pressure Pl and Hbl fractionation as the main differentiation mechanism in shallow magma reservoirs, suggested by the increasing Eu, Sr, and MREE anomalies in samples with high","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105199"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143182215","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":"Thermobarometry applied to the long-lived Cordillera de San Buenaventura volcanic complex in Central Andes. Part II: The effect of “liquid” in inverse modelling","authors":"L. Bardelli ,&nbsp;C. Zhang ,&nbsp;E. Bustos ,&nbsp;M. Arnosio ,&nbsp;R. Becchio ,&nbsp;R. Filipovich ,&nbsp;J. Viramonte ,&nbsp;F. Lucci","doi":"10.1016/j.jsames.2024.105318","DOIUrl":"10.1016/j.jsames.2024.105318","url":null,"abstract":"<div><div>The Cordillera de San Buenaventura is a long-lived Neogene-to-Holocene multifaceted volcanic system located in the southern sector of the Altiplano Puna (NW Argentina). The erupted products span from mafic to high-SiO₂ rhyolites, all of which are characterized through time from the same primary assemblage made up of Cpx-Opx-Bt-Hbl-Pl-San-Ol-Mag-Ilm. Recent studies highlighted a common line of descent mainly controlled by amphibole + plagioclase fractionation, and a transcrustal magmatic plumbing system comprising discrete magma storage zones. However, the existing characterization of the anatomy of the magmatic plumbing system derives mainly from inverse mineral-melt thermobarometry models applied to a limited number of the presumed “mineral-melt equilibrium pairs” identified through tests based on Mg-Fe partitioning between phases. In this short communication, we show how the signal of such tests could be misleading due to the multifaceted significance of the mineral-liquid equilibrium in a suprasolidus environment, and therefore how it is preferable the coupling with other inverse thermobarometry model based on the mineral chemistry only. Through this approach, we demonstrate here how the Cordillera the San Buenaventura is vertically distributed along the whole crust, but how major phenocryst phases (Cpx, Opx, Bt, Amp) probably crystallized/fractionated in very limited zones of the plumbing system and then travelled as crystal cargo in the ascending residual liquids.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105318"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143179754","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 as a monitor for petrogenetic processes and its implications for the provenance of sanukitoids and other Archean rocks from the Rio Maria Domain, southeastern of the Carajás Province, Brazil","authors":"Camila Santos da Fonseca ,&nbsp;Aline Costa do Nascimento ,&nbsp;Gisele Tavares Marques ,&nbsp;Cláudio Nery Lamarão ,&nbsp;Davis Carvalho de Oliveira ,&nbsp;Roberto Dall’Agnol ,&nbsp;José de Arimatéia Costa de Almeida ,&nbsp;Rubem Santa Brígida Barros Neto","doi":"10.1016/j.jsames.2024.105291","DOIUrl":"10.1016/j.jsames.2024.105291","url":null,"abstract":"<div><div>The granitogenesis of the Rio Maria domain, located in the southern of the Carajás province, is characterized by the presence of a variety of Archean granitoids formed between 2.98 and 2.86 Ga, along with Paleoproterozoic anorogenic granites dating to 1.88 Ga. The study of the morphology and chemical composition of apatites crystals has been employed to assess the magmatic evolution of igneous rocks. This work presents the results of chemical analyses conducted using an electron microprobe on apatites from sanukitoids in the regions of Rio Maria, Bannach, and Ourilândia do Norte, as well as from the Ba-Sr-rich leucogranodiorite Nova Canadá and the TTG-affinity Mogno trondhjemite, all of which are of Archean origin. Additionally, apatites crystals from the Paleoproterozoic oxidized anorogenic Seringa granite are included for comparison. Apatites crystals from the sanukitoids of Ourilândia do Norte and Rio Maria exhibit lower fluorine (F) content and higher levels of lanthanum (La), cerium (Ce), praseodymium (Pr), samarium (Sm), and europium (Eu) compared to similar sanukitoids found in Bannach. Based on the geochemical signatures of apatites crystals, it is suggested that the magmas of the sanukitoids of the Ourilândia do Norte and Rio Maria may have originated from mantle sources with a higher degree of metasomatism and/or enriched in rare earth elements (REE) and yttrium (Y), while the magmas of the Bannach sanukitoids may have derived from a mantle less intensely metasomatized and comparatively depleted in REE + Y. Apatite crystals from the Mogno trondhjemite and the Ba-Sr-rich Nova Canadá leucogranodiorite are depleted in REE + Y and resemble the apatites of the Bannach sanukitoids, although the apatites in the leucogranodiorite are more enriched in strontium (Sr).The Seringa granite has apatite crystals with higher F and REE + Y content when compared to apatites from the Archean rocks, indicating that apatite compositions can be used to distinguish between Archean and Paleoproterozoic granitoids, thus providing valuable contributions in provenance studies.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105291"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181203","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":"Modeling orbital data of soil carbon dioxide efflux from different land uses in Southern Amazon","authors":"João Lucas Della Silva ,&nbsp;Mendelson Lima ,&nbsp;Larissa Pereira Ribeiro Teodoro ,&nbsp;Luís Guilherme Teixeira Crusiol ,&nbsp;Newton La Scala ,&nbsp;Fernando Saragosa Rossi ,&nbsp;Damien Arvor ,&nbsp;Paulo Eduardo Teodoro ,&nbsp;Carlos Antonio da Silva Junior","doi":"10.1016/j.jsames.2024.105323","DOIUrl":"10.1016/j.jsames.2024.105323","url":null,"abstract":"<div><div>The dynamics of carbon among atmospheric, soil and biotic stocks are of great importance for ecosystem and climate services. The interdependence of carbon stocks is volatile, since higher atmospheric CO₂ concentrations affect plant development and therefore carbon storage in terrestrial ecosystems. In addition, the carbon cycle is related to soil moisture, and sensitivity to moisture differs between ecosystems and climatic regions. In the southern Amazon, agriculture and cattle ranching activities drives anthropogenic actions and for the environmental costs. As a result, those activities impact carbon dynamics and its consequences on the environment. Modeling these dynamics in a spatialized way is possible through remote sensing images, which, together with appropriate modeling tools, allow us to understand the carbon balance at a regional level. The aim of this study is discussing the modeling of the soil carbon dioxide efflux (FCO₂) from different land uses for orbital data predictions using MODIS and PlanetScope imagery. Local data was the reference for the orbital data modeling with partial least squares regression (PLSR). Discussed models are based on soil moisture, temperature, spectral bands and also models with MODIS GPP and CO2Flux were created. Land uses (characterized by high and low productivity soybeans, degraded pasture, productive pasture and native forest) and consisted of different subsets of inputs subsets to design PLSR equations. Results analyzes were based on the statistical metrics of linear regression (R²), mean absolute error (MAE) and root mean square error (RMSE). From those methods, it was observed that the subsets with the lowest error and highest correlation were the subsets related to soybeans. The homogeneity of soybean areas and its spectral characteristics mean greater capacity for predicting FCO₂, since the orbital images and PLSR modeling provide a higher correlation and lower error, both absolute and quadratic. On the other hand, carbon balance modeling in forest areas and pastures is limited and potentially associated with the heterogeneity of that environment.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105323"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143180733","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":"Landslide and flood risk assessment in a rapidly urbanizing municipality of Costa Rica","authors":"Marco Acosta-Quesada,&nbsp;Adolfo Quesada-Román","doi":"10.1016/j.jsames.2024.105330","DOIUrl":"10.1016/j.jsames.2024.105330","url":null,"abstract":"<div><div>Landslides and floods are among the most prevalent hazards in tropical and developing regions, often exacerbated by rapid urbanization and unregulated land management. Santa Ana, a rapidly expanding municipality in Costa Rica, presents a unique mix of high-value residential properties, commercial hubs, agricultural lands, and protected areas, making it vulnerable to both landslides and floods. This study integrates geomorphological (morphometric and morphogenetic) methods to assess landslide and flood hazards, considering key variables such as slope, L-S factor, terrain roughness, topographic wetness index, and flow accumulation. Additionally, socioeconomic data—including population density, infrastructure, and land use—are combined with the Social Development Index (SDI) to evaluate exposure and vulnerability. Through the use of normalized indices, a comprehensive risk map is developed, highlighting high-risk zones, particularly in districts like Salitral and Brasil, where steep slopes and dense hydrological networks coincide with higher socio-economic vulnerabilities. The study provides an adaptable framework for disaster risk management, applicable to regions with limited data availability, facilitating timely and informed territorial planning decisions aimed at mitigating risks and enhancing community resilience.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105330"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181770","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":"Linking large-volume landslides with potential neotectonic activity of the Pocuro fault system, Central Andes (32°-33°S)","authors":"José Tomás G. Urrejola-Sanhueza ,&nbsp;Sergio A. Sepúlveda ,&nbsp;Luisa Pinto ,&nbsp;Stella M. Moreiras","doi":"10.1016/j.jsames.2024.105320","DOIUrl":"10.1016/j.jsames.2024.105320","url":null,"abstract":"<div><div>The link between large-volume landslides and a potential seismic source has not been extensively tackled in the seismic central Chile even though many mega-landslides have been triggered historically by earthquakes. In this research, an inventory of prehistoric landslides was developed on the western border of the Andes Principal Cordillera, identifying 41 large-volume landslides along main regional structures of the Pocuro Fault System. Among them, 8 landslides were selected to determine a probable seismic source. Slide modelling was performed by reconstructing the topography previous to failure obtaining geotechnical parameters from compressive strength tests and RMR-GSI values collected during field work. Slope stability models were carried out by implementing pseudostatic limit equilibrium analyses in slopes where critical accelerations for sliding were determined. Back-analysis applying inversely Ground Motion Models to nearby mapped faults and topographic amplification depicted cases where a coseismic origin of the landslides is likely. Several faults of the Pocuro Fault System are identified as possible seismogenic sources of the instabilities, suggesting neotectonic activity of this Quaternary fault system, consistent with recent paleoseismological studies in the area and the occurrence of high magnitude earthquakes in this region.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105320"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181775","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":"Coastal spatial planning using object-based image analysis and image classification techniques","authors":"Senthilkumar C ,&nbsp;Eatedal Alabdulkreem ,&nbsp;Nuha Alruwais ,&nbsp;Kavitha M","doi":"10.1016/j.jsames.2024.105322","DOIUrl":"10.1016/j.jsames.2024.105322","url":null,"abstract":"<div><div>This study focuses on optimizing coastal spatial planning for Rio de Janeiro, Brazil, addressing critical challenges such as unmanaged urbanization, loss of natural habitats, and land degradation. Utilizing Object-Based Image Analysis (OBIA) and Image Classification techniques within QGIS, the research examines Land Use/Land Cover (LULC) data from 2005, 2015, and 2024. Using the Molusce tool for spatial modeling, land use patterns were predicted for 2035 and 2045. Key spatial parameters analyzed include proximity to rivers, land value, slope level, and population density. Significant trends include a decline in water bodies (3.70% in 2005 to 2.70% in 2045), a surge in built-up areas (29.33%–43.99%), and a reduction in forest cover (38.70%–30.26%). Additionally, barren land is expected to increase from 6.26% to 15.35%, reflecting environmental degradation, while agricultural land shows a steep decline (21.32%–5.59%), driven by urban sprawl and economic shifts. Salt pans, though minimal, are projected to rise from 0.69% to 2.11%. These changes highlight pressing issues like habitat destruction, declining agricultural land, and rising urban pressures in the region. The study underscores the importance of integrated coastal management strategies to balance development and sustainability. Predictive modeling tools in QGIS provide actionable insights for policymakers to anticipate land use changes and implement proactive measures for urban and environmental planning.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105322"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143180730","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":"Energy balance and Evapotranspiration response to environmental variables in the semi-arid Caatinga biome","authors":"Rayonil G. Carneiro ,&nbsp;Zuzanna Rykowska ,&nbsp;Camilla K. Borges ,&nbsp;Iwona S. Stachlewska ,&nbsp;Carlos A.C. dos Santos","doi":"10.1016/j.jsames.2024.105319","DOIUrl":"10.1016/j.jsames.2024.105319","url":null,"abstract":"<div><div>Semi-arid regions worldwide face critical challenges related to prolonged droughts and limited water availability, which significantly impact ecosystem dynamics and plant productivity. This study investigates the energy balance and the phenomenon of hysteresis between actual evapotranspiration (ET) and environmental variables in areas of Dense Caatinga (DC) and Sparse Caatinga (SC) using micrometeorological data collected between 2013 and 2015. It was observed that sensible heat flux (H) was the main component of the energy balance, representing more than 50% of the available energy. In comparison, latent heat flux (LE) varied between 20% annually and 40% during the rainy season. The energy balance closure was satisfactory, with closure coefficients ranging from 65% to 88% depending on the season and vegetation type. In SC, with a more exposed surface, the conversion of net radiation (Rn) at the surface into H is increased. In both regions, during dry periods, LE decreases mirroring the scarcity of water availability. The hysteresis analysis revealed complex cycles of ET in relation to net radiation (Rn), air temperature (Temp), and vapor pressure deficit (VPD), with significant interannual variations. The correlation between ET and gross primary productivity (GPP) indicated counterclockwise hysteresis patterns in DC, suggesting that changes in GPP precede and influence ET, reflecting a rapid stomatal response to increased photosynthetic activity. In SC, the hysteresis cycles between ET and GPP were more variable, displaying both counterclockwise and clockwise loops, especially during 2015, strongly influenced by the El Niño event, indicating lower efficiency in the ET response to GPP due to water constraints. Canopy conductance (Gc) and the decoupling coefficient (Ω) also showed seasonal variations, reflecting the ecophysiological responses to environmental conditions. The correlation between these two variables suggests that Gc in SC was more influenced by external factors, like radiation and water availability. These results demonstrate that the dynamics of the Caatinga Biome are strongly tied to seasonal rainfall patterns, as the ecosystem's physiological and metabolic traits are primarily regulated by water availability. The variations observed across years and vegetation types underscore the importance of considering interannual variability and the distinctive characteristics of the ecosystem when analyzing climate relationships.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105319"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143180732","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":"Cryogenian magmatic arc detrital ages and superposition of metamorphic events in metasedimentary rocks from the Andrelândia and Juiz de Fora domains, Juiz de Fora, Minas Gerais","authors":"André Campos Rocha ,&nbsp;Beatriz Paschoal Duarte ,&nbsp;Mauro Cesar Geraldes ,&nbsp;Ariane Felix Coelho Azevedo ,&nbsp;Thayla Almeida Teixeira Vieira ,&nbsp;Rafael Cardoso de Moraes Telles ,&nbsp;Marcos Silva Machado ,&nbsp;Wagner Travassos Lemos ,&nbsp;Julio Cezar Mendes","doi":"10.1016/j.jsames.2024.105260","DOIUrl":"10.1016/j.jsames.2024.105260","url":null,"abstract":"<div><div>The present study focuses on a paleobasin, in which metasedimentary rocks of the Andrelândia/Raposos Groups outcrop, along with diatexites and intrusive metagranitoids. The basin is located in the contact between the Andrelândia and Juiz de Fora Domains, subdivisions of the Occidental Terrane of the Ribeira Orogen; being also in lateral continuity with the Lima Duarte Nappe, interpreted as part of the Brasília Orogen. Rocks of both domains are affected by distinct metamorphic grades, with peak metamorphism at upper amphibolite facies in the Andrelândia Domain (above 650 °C and 7 kbars) and granulite facies (above 750 °C) in the Juiz de Fora Domain. Tourmaline-bearing metawackes occur along a significant shear zone between these two domains. These rocks are situated in the Andrelândia Domain, being characterized by a mylonitic texture with a fine grayish matrix, with clear contrast to plagioclase porphyroclasts. The metawackes locally grade into quartzites and sillimanite rich schists, also disposing lenses of calc-silicate rocks, amphibolites, and meta-ultramafic rocks. Exhalative origin minerals such as tourmaline and gahnite suggest sedimentation conditions in deep sea, associated with submarine fumaroles. Geochemical results point to a main source of intermediate composition and a magmatic arc environment context of sedimentation. U-Pb dating of the metawackes reveals a main detrital peak at ca. 678 Ma, correlated with the granitic plutons of the Socorro Nappe as the main source. Mylonitic metasedimentary rocks from the Juiz de Fora Domain were also studied for comparison. Detrital zircons of these samples reveal main peaks at ca 2079 and 1714 Ma, indicating a different provenance for these rocks compared to the metawackes of the Andrelândia Domain. Another studied lithotype is a mica schist containing green kyanite, outcropping in the Andrelândia Domain. U-Pb dating reveals a main source at ca. 2040 Ma and a secondary source at ca. 2719 Ma, correlated, respectively, with the Mantiqueira and Piedade Complexes. Garnet charnockites emerge as diatexites from the partial melting of metasedimentary rocks in the Juiz de Fora Domain. The zircon crystallization age of these charnockites at 621 ± 1.7 Ma marks the collision of these terranes, as well as the granulite peak metamorphism of the Juiz de Fora Domain. The metamorphic peak of the Andrelândia Domain is recorded by the formation of kyanite, a characteristic commonly described for rocks of the Brasília Orogen. A period of rapid tectonic exhumation is responsible for the re-equilibrium of parageneses under medium pressure/temperature conditions. A third event at 595 - 560 Ma, related to the collision with the Rio Negro Magmatic Arc, generates mylonitic texture in the rocks and contributes to the formation of a hydrated paragenesis, due to fluid percolation from the shear zones.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"152 ","pages":"Article 105260"},"PeriodicalIF":1.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143180772","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}