Journal of South American Earth Sciences最新文献

{"title":"The post-depositional evolution of Mesoproterozoic to early Neoproterozoic tight sandstone reservoirs, São Francisco basin, Brazil","authors":"Jéssica Melanya Sisti de Paiva ,&nbsp;Angélica Fortes Drummond Chicarino Varajão ,&nbsp;Humberto Luis Siqueira Reis ,&nbsp;Newton Souza Gomes ,&nbsp;João F. Suss","doi":"10.1016/j.jsames.2024.105278","DOIUrl":"10.1016/j.jsames.2024.105278","url":null,"abstract":"<div><div>This study presents the first comprehensive assessment of unconventional gas reservoirs in the Proterozoic sequences of the intracratonic São Francisco basin, providing depositional and post-depositional characterization and insights into reservoir quality. Detailed stratigraphic, petrological, and seismic analyses, integrated with 2D seismic data, were performed to evaluate the influence of diagenesis and hydrothermal fluids. The drill core was drilled in the central sector of the basin and within the southern border of the Pirapora aulacogen, in a 303 m-thick interval of the Paranoá-Upper Espinhaço sequence. The petrological analysis shows arkoses and sublitharenites as well as conglomerates, siltstones and mudstones successions deposited in deltaic, fluvial braided and marine depositional systems. Six sedimentary environments were identified, from the base to the top: (i) deltaic plain, (ii) delta front, (iii) braided fluvial, (iv) delta front, (v) prodelta and (vi) basin plain. The integration of seismic data review three depositional domains, characterized by lower frequency arranged to transgressive-regressive cycles identified by gamma ray, resistivity and density logs. The studied strata review eo - and mesodiagenetic alterations, being also influenced by intrusion-related hydrothermal and contact metamorphism. The main diagenetic events resulted in cementation of calcite (0.84%), chlorite (1.23%) and silica (6.19%), which largely obliterated porosity at the shallow burial depths. The main secondary porosity is intergranular, with minor contributions to intragranular, fracture, moldic and vugular. Diagenetic processes as well as the influence of hydrothermal processes highlight the complexity of post-depositional processes in these units. The presence of natural helium and hydrogen within the basin also suggests that these reservoirs should be considered in future exploration campaigns targeting unconventional energy resources.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105278"},"PeriodicalIF":1.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743667","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":"Ediacaran magmatism in the Dom Feliciano Belt and Nico Pérez Terrane between the Sierra Ballena and Sarandí de Yí shear zones, central Uruguay: Insights based on geochemistry, geochronology, and isotopy","authors":"S. Fort,&nbsp;E. Peel","doi":"10.1016/j.jsames.2024.105276","DOIUrl":"10.1016/j.jsames.2024.105276","url":null,"abstract":"<div><div>Ediacaran granitic magmatism occurs both within the Archean-Paleoproterozoic Nico Pérez Terrane and the metavolcanosedimentary sequences of the Dom Feliciano Belt (DFB). Despite its fundamental role in understanding the geologic evolution of the region, there is scarce geological information available on this magmatism in central-east Uruguay. For this reason, this article presents petrographic, geochemical, geochronological, and isotopic data from several plutons located in the central portion of Uruguay to assess this granitic magmatism involved in the waning stages of the Brasiliano Orogeny. The predominant lithologies are syenogranites and monzogranites, with subordinate quartz-syenite, quartz-monzonite, and quartz-monzodiorite. Their ages place the magmatism between 620 Ma and 590 Ma, similar to what is observed in other segments of the Dom Feliciano Belt. The geochemical data indicate that the magmatism is slightly peraluminous, predominantly ferroan with occasional magnesian granites, and belongs to the alkalic to alkali-calcic series, with only a few calc-alkalic bodies. Two possible magmatic sources are inferred based on trace element contents, referred to as the LBS (low Ba-Sr) source and HBS (high Ba-Sr) source. The LBS source is characterized by negative Eu anomalies, classified as low Ba-Sr granites, having a low Sr/Y ratio (≤30), and presenting lower alkali enrichment. Conversely, the HBS source is characterized by the absence of Eu anomalies, classified as high Ba-Sr granites, with higher Sr/Y ratios (&gt;40) and generally higher alkali enrichment. The geochemical and isotopic data suggest the involvement of deep crustal material with subordinate metasedimentary participation, with a higher metasedimentary contribution in the LBS source. Furthermore, the model ages between 2.08 Ga and 2.83 Ga, along with the inherited zircon crystals, indicate a significant reworking of an Archean-Paleoproterozoic crust for the whole magmatism. The emplacement of this magmatism is restricted to an orogenic setting, particularly classifying as Late Syn-Collisional to Early Post-Collisional peraluminous granites.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105276"},"PeriodicalIF":1.7,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743666","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 deltaic palaeoenvironments in southern South America: phytoliths in Miocene estuarine sediments (Paraná Formation)","authors":"Noelia I. Patterer ,&nbsp;Eliana Moya ,&nbsp;Sebastián A. Frezzia","doi":"10.1016/j.jsames.2024.105269","DOIUrl":"10.1016/j.jsames.2024.105269","url":null,"abstract":"<div><div>This study provides new insights into the palaeoenvironments that developed during the Late Miocene in Argentina and represents the first palaeobotanical record for the Paraná Formation at the Salto Ander Egg site. The analysis of the phytolith assemblages identified new morphotypes not previously documented in the literature for the sediments of this region. The importance of these discoveries lies in their potential taxonomic relevance to plant components associated with mangrove environments. The stratigraphic column in the study area is made up of the Paraná Formation (Late Miocene) and other Neogene and Quaternary geological formations. Samples of three sedimentary cycles were taken for the analysis of the phytoliths in levels with internal discontinuities and a high density of sub-vertical tubular biogenic structures and horizontal extensions. The morphotypes identified suggest the presence of species with pneumatophores, features typically found in intertidal mangrove forests. This study highlights the potential of phytolith analysis as a valuable tool for characterising deltaic palaeoenvironments. The phytolith assemblages from the Paraná Formation sediments provide important preliminary insights into a palaeoenvironment that possibly included mangrove forests and saline-adapted plant communities, existing in an ecosystem with freshwater availability within a saline environment, under a warm tropical to subtropical climate.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105269"},"PeriodicalIF":1.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New pterosaur fossils from the Early Cretaceous of Colombia","authors":"Edwin-Alberto Cadena ,&nbsp;Dubban A. Atuesta-Ortiz ,&nbsp;Jeffrey A. Wilson Mantilla","doi":"10.1016/j.jsames.2024.105273","DOIUrl":"10.1016/j.jsames.2024.105273","url":null,"abstract":"<div><div>The fossil record of pterosaurs in northwestern Gondwana has been relatively scarce, with only two previous occurrences. This study presents new pterosaur findings from three sites in Colombia, including a new record of an <em>Anhanguera</em>-like specimen and other bones referrable to Anhangueria. The new material includes a distinctive partial lower jaw found in association with parts of a radius and a complete distal syncarpal. The lower jaw has a triangular glenoid fossa in dorsal view, a fossa depressoria with a bean-shaped outline, and a retroarticular process with a straight margin in lateral or medial views. The new fossils extend the record of <em>Anhanguera</em>-like pterosaurs into the earliest part of the Cretaceous and expand our knowledge of the vertebrate fossil record of lower latitudes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105273"},"PeriodicalIF":1.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703635","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":"Hydrocarbon generation in the onshore and offshore of the Austral and Malvinas basins based on 3D petroleum system modelling","authors":"Juan B. Spacapan ,&nbsp;Ignacio Brisson ,&nbsp;David Giunta ,&nbsp;Marcos Comerio ,&nbsp;Lara Fernández Kavanagh ,&nbsp;Agustín Pineda ,&nbsp;Laura Loss ,&nbsp;Julieta Ventisky ,&nbsp;Nicolas Seoane ,&nbsp;Hugo Freije ,&nbsp;Néstor D. Bolatti","doi":"10.1016/j.jsames.2024.105274","DOIUrl":"10.1016/j.jsames.2024.105274","url":null,"abstract":"<div><div>The Austral and Malvinas basins are prolific oil and gas provinces, estimated to contain a significant proportion of undiscovered hydrocarbon reserves in the South Atlantic. A three-dimensional basin and petroleum system model (3D BPSM) is presented to visualize the complex deformation history which impacted in the volumes of generated hydrocarbons from the Lower Cretaceous source rock (LC-SR) in fold-and-thrust belt (FTB) regions through geological time. Organic geochemistry and maceral analysis obtained from samples from 28 wells were incorporated to 3D BPSM to evaluate the source rock potential from the Austral to Malvinas basins. The LC-SR contains a type II to type II–III kerogen with most samples showing a regular to good (&gt;1%), and in few cases, excellent (&gt;4%) TOC contents in both basins. Modelling results show higher source rock maturities (dry gas window) and kerogen transformation that occurred towards the fold-and-thrust belt regions, where deeper burial conditions were reached. A general decrease of maturity is observed towards the foreland regions of both basins. From Late Cretaceous large volumes of hydrocarbons were generated and expelled in fold and thrust belt regions of Austral and Malvinas basins. The main phase of hydrocarbon generation occurred during the Eocene, when the LC-SR reached the maximum burial, especially in the Fuegian-FTB. Hydrocarbon generation and expulsion continue to the present, particularly in the kitchen located in the eastern sector of the Malvinas Basin.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105274"},"PeriodicalIF":1.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721648","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":"An integrated approach to characterize diabase sills in Parnaíba Basin, based on geochemical data, cuttings description, and well logs interpretation","authors":"Bruna Maia Imbuzeiro ,&nbsp;Filipe Vidal ,&nbsp;Bruno de Sá Nobre da Rocha ,&nbsp;Carla Semiramis Silveira ,&nbsp;Wagner Moreira Lupinacci ,&nbsp;Victor Salgado-Campos ,&nbsp;Antonio Fernando Menezes Freire","doi":"10.1016/j.jsames.2024.105263","DOIUrl":"10.1016/j.jsames.2024.105263","url":null,"abstract":"<div><div>Igneous rocks play a fundamental role in the formation and evolution of petroleum systems in several basins around the world. In the Parnaíba Basin, northestern Brazil, the diabase sills and dikes, which compound the Mosquito and Sardinha formations, contribute as a thermal source for an unconventional hydrocarbon generation, as well as providing trap and seal for the petroleum system. To understand these intrusions, we propose a methodology to identify the igneous intrusions in well-logs and interpret their compositional variations. The methodology is based on detailed descriptions of cuttings, X-ray fluorescence (XRF), X-ray diffractometry (XRD) and well logs, such as Gamma Ray (GR), Density (RHOZ) and Photoelectric Factor (PEFZ), from six exploratory wells drilled in the main gas-producing area of the Parnaíba Basin. The intrusions present in these wells were identified through the Igneability Feature and classified based on the GR curve as either <em>“Barriguda”</em> or <em>“Caixote”</em> patterns. The <em>“Barriguda”</em> intrusions show variations in the well logs (GR, RHOZ and PEFZ) along their vertical section, as well as variations in aluminum, calcium, potassium, zirconium, iron, titanium, magnesium, nickel and chromium values, evidencing a great textural and mineralogical variation, confirmed by the mineralogical results of XRD. Data interpretation suggests that the <em>“Barriguda”</em> intrusions are characterized in distinct electrofacies- and chemiofacies that represent an internal variation from top to base, related to magmatic differentiation processes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105263"},"PeriodicalIF":1.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743668","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":"Advanced landslide susceptibility mapping and analysis of driving mechanisms using ensemble machine learning models","authors":"Mashael Maashi ,&nbsp;Nada Alzaben ,&nbsp;Noha Negm ,&nbsp;V. Venkatesan ,&nbsp;S. Sabarunisha Begum ,&nbsp;P. Geetha","doi":"10.1016/j.jsames.2024.105272","DOIUrl":"10.1016/j.jsames.2024.105272","url":null,"abstract":"<div><div>This study focuses on advanced landslide susceptibility mapping in Bertioga, utilizing ensemble machine-learning models to identify and predict landslide-prone regions. Four algorithms—Adaptive Boosting (AdaBoost), Gradient-Boosting Decision Tree (GBDT), Multilayer Perceptron (MLP), and Random Forest (RF)—were employed to model landslide susceptibility at a 30-m spatial scale, using thirteen landslide conditioning factors (LCFs). These LCFs include topographical, geological, and environmental variables significantly influencing landslide occurrence. The performance of each model was evaluated based on precision (P), recall (R), F1-Score, and area under the curve (AUC), ensuring a robust assessment of prediction accuracy. Furthermore, the models demonstrated varying area coverage in terms of susceptibility classes. For instance, MLP identified 15% of the study area as very low susceptibility, 22% as low, 18% as moderate, 18% as high, and 27% as very high. RF predicted 40% of the region as very low susceptibility, whereas GBDT indicated a substantial 45% of the area as very high risk. AdaBoost, on the other hand, assigned the highest moderate risk coverage at 31%. These results provide a comprehensive understanding of the spatial distribution of landslide risks. Results show that MLP and GBDT achieved higher accuracies in the susceptibility mapping, with AUC values ranging from 0.85 to 0.96. For instance, in Parque CauiBura, MLP and GBDT performed exceptionally well with AUC scores of 0.98 and 0.97, respectively. The average prediction for all cities yielded a high accuracy of 0.95 in Parque CauiBura, followed by 0.92 in Centro. These findings highlight the importance of using ensemble machine learning techniques in regional landslide susceptibility mapping, offering valuable insights for risk management and mitigation strategies in landslide-prone areas such as Bertioga.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105272"},"PeriodicalIF":1.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703636","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":"Petrological relationships between plutonic and volcanic rocks in a continental volcanic arc system: Evidence from plutonic xenoliths in the Sierra de Pachuca, Mexico","authors":"Raymundo G. Martínez-Serrano ,&nbsp;Diana Contreras-Cruz ,&nbsp;Miriam V. Núñez-Velázquez ,&nbsp;Brenda B. Ramírez-Ramírez","doi":"10.1016/j.jsames.2024.105271","DOIUrl":"10.1016/j.jsames.2024.105271","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Relatively abundant plutonic xenoliths found in some lava domes, lava flows, and scoria cone deposits were employed to study the features and processes between the magmatic plumbing systems and volcanic rocks in the Sierra de Pachuca, central-eastern Mexico. We present petrographic, geochemical, isotopic data and five U-Pb ages for some plutonic xenoliths and the Sierra de Pachuca host rocks to provide evidence of magmatic processes existing under this volcanic range. The phaneritic plutonic xenoliths were grouped into six lithological types based on petrography, chemical data, and isotopic ages. Four types (A to D) are hosted by the El Ventoso lava dome. Their compositions span from calc-alkaline gabbro to granite, with U-Pb zircon ages ranging from 23.1 ± 1.4 to 21.6 ± 0.6 Ma. These ages are contemporaneous with the emplacement of rhyolitic ignimbrites found at the base of the Sierra de Pachuca (22.8 ± 0.5 Ma U-Pb zircon age). The trace element patterns for these Late Oligocene-Early Miocene plutonic xenoliths display enrichment of LILE relative to HFSE and enrichment of LREE respecting to HREE typical of subduction-related rocks. Negative P, Ti, and Eu anomalies in these patterns also suggest fractional crystallization processes in magmas that produced the A to D types. Two more types of plutonic xenoliths (E and F) display gabbro and syenite compositions, respectively, and are hosted by the San Miguel-Santa María Regla columnar jointed basalts (gabbro samples) and by the El Prieto scoria cone (syenite samples). Based on one U-Pb zircon age (2.4 ± 0.2 Ma) and geological correlations, these plutonic xenoliths and their host rocks were emplaced in the Quaternary. They exhibit alkaline compositions, and their trace element patterns indicate an enriched mantle source with positive Ba and Pb anomalies, not typical of subduction-related magmas. The isotopic values (&lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr = 0.70390 to 0.70502 and εNd = −2.99 to +0.76) for the Late Oligocene-Early Miocene A to D types and host rocks suggest the interaction of magmas with continental crust components. In contrast, the Quaternary xenoliths of E and F types and their host rocks display isotopic data (&lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr = 0.70396 to 0.70602 and εNd = +0.13 to +3.66) that evidence of less interaction with continental crust components. In all studied xenoliths, the Pb isotopic ratios (&lt;sup&gt;206&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb = 18.60–18.87; &lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb = 15.57–15.63 and &lt;sup&gt;208&lt;/sup&gt;Pb/&lt;sup&gt;204&lt;/sup&gt;Pb = 38.39–38.68) lie on a mixing line between a mantle-like member and a radiogenic component such as the Paleozoic Acatlán complex that probably underlie the Sierra de Pachuca area. Based on the results obtained, it is proposed that the Late Oligocene-Early Miocene A to D type xenoliths represent the plumbing systems from which the volcanic rocks of the Sierra de Pachuca were extruded. On the other hand, the E and F types also represent the roots ","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105271"},"PeriodicalIF":1.7,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703633","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 long fossil trackway assigned to an ungulate from the Chiquimil Formation (Late Miocene, Messinian), Santa María valley, Catamarca, Argentina","authors":"Matías A. Armella ,&nbsp;Pablo E. Ortiz ,&nbsp;Lucía Ibáñez ,&nbsp;M. Carolina Madozzo Jaén ,&nbsp;Vanessa Torres Carro","doi":"10.1016/j.jsames.2024.105270","DOIUrl":"10.1016/j.jsames.2024.105270","url":null,"abstract":"<div><div>The late Neogene sediments in northwestern Argentina have yielded a rich assemblage of fossil vertebrate remains, primarily consisting of skeletal elements. While these remains have provided valuable information, incorporating other types of evidence could further deepen our understanding of past communities. In this contribution, we study fossil trackways preserved in the Chiquimil Formation (Late Miocene, Messinian) of the Santa María valley, Catamarca Province, Argentina. The footprints exhibit a tridactyl morphology with distinctive features (e.g., U-shaped concavity on the posterior margin, central digit longer than the lateral digits), which has allowed their attribution to <em>Macrauchenichnus</em> cf. <em>M. troyana</em>. This finding is one of the longest and best-preserved trackway assigned to this ichnotaxon. The morphology and estimated body mass of the trackmaker align with hypotheses suggesting macraucheniid litopterns as producers, representing the first evidence of these ungulates in the area. This finding not only expands our knowledge of the paleobiodiversity of the region but also presents a unique opportunity for educational and ecotourism initiatives. The accessible location of the trackway and its potential for promoting scientific knowledge and local development make it a valuable resource for the community.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105270"},"PeriodicalIF":1.7,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721649","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, Hf isotopes and trace elements of zircon reveals a Mesoproterozoic crustal source for the Jurassic Caopas sub-volcanic intrusion: Northern part of the Nazas Igneous Province in Mexico","authors":"Roberto Carlos Gómez-Torres ,&nbsp;José G. Cavazos-Tovar ,&nbsp;Gabriel Chávez-Cabello ,&nbsp;José Jorge Aranda-Gómez ,&nbsp;César Francisco Ramírez-Peña","doi":"10.1016/j.jsames.2024.105266","DOIUrl":"10.1016/j.jsames.2024.105266","url":null,"abstract":"<div><div>The Caopas sub-volcanic intrusion crops out in the northern area of the Nazas Igneous Province. Due to its extension (∼70 km²), this intrusion is the largest igneous body within this province. At the same time, its location, close to the boundary between the Central terrane and Oaxaquia microcontinent, highlights its relevance to understanding the role that the basement plays in the genesis of the Caopas sub-volcanic intrusion. In this paper we present whole rock geochemical data of major and trace elements, U-Pb ages, Hf isotopes and trace elements in single zircon grains from samples of the Caopas sub-volcanic intrusion (U-Pb zircon age: ∼166.97 ± 0.96 Ma). Geochemical data indicate that the rocks studied are peraluminous (Al/CNK ≥1). The analyzed zircon grains exhibit enriched Hf isotopic compositions (εHf_(t) from −1.6 to 2.5), high U/Yb values and negative Eu anomalies, suggesting, along with the geochemical data, that these magmas were formed by significant volumes of crustal melts during their genesis. The Hf model ages in zircon grains are consistent with a Mesoproterozoic crustal source for the magmas that formed the intrusive (∼1023 Ma to ∼1282 Ma), which coincides with ages reported for rocks in the crystalline basement of the area (i.e. the Oaxaquia microcontinent).</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"151 ","pages":"Article 105266"},"PeriodicalIF":1.7,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703643","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}