Journal of South American Earth Sciences最新文献

{"title":"Metamorphic P-T-d evolution path of ductile-sheared rocks of Cerro Catedral, North Patagonian Andes of Argentina: From high-P/T Late Paleozoic progression to low-P/T Jurassic overprint","authors":"Franco D. Bianchi , Juan Cruz Martínez , Hans-Joachim Massonne , Sergio H. Delpino , Jorge A. Dristas","doi":"10.1016/j.jsames.2024.105216","DOIUrl":"10.1016/j.jsames.2024.105216","url":null,"abstract":"<div><div>A petrological study, combined with field and microstructural evaluation of metapelites, metabasites and a tonalitic to quartz-dioritic rock of Cerro Catedral, North Patagonian Andes of Argentina, reveals the protracted polyphase deformational and metamorphic evolution of the area during the Late Paleozoic to Mesozoic. The 11-component system Si–Ti–Al–Fe–Mn–Mg–Ca–Na–K–O–H was used to model the bulk-rock composition of a mylonitic garnet- and andalusite-bearing micaschist. For this purpose, a P-T pseudosection was calculated using the GeoPs software and contoured with isopleths and mineral isomodes of interest. Refractory zoned garnet typically exhibits a prograde bell-shaped compositional zoning. Its core (gros + andr<sub>0.29</sub>, spes<sub>0.13</sub>, pyr<sub>0.02</sub>, alm<sub>0.55</sub>) to rim (gros + andr<sub>0.22</sub>, spes<sub>0.05</sub>, pyr<sub>0.04</sub>, alm<sub>0.69</sub>) compositions yield a prograde path from initial conditions of ∼9 kbar and 490–500 °C to ∼12 kbar and 510 °C. The remnant compositions (Si: 3.10–3.18 apfu) of K-white mica of the dominant S<sub>2m</sub>-foliation support these physical conditions. The, thus, calculated low geothermal gradient of 11–14°Ckm<sup>−1</sup> suggests that the studied rocks were transported to a maximum depth of ∼45 km in a shallow paleosubduction zone. Microstructures of coalescent quartz ribbons might indicate a peak temperature around 650 °C after peak pressure conditions. These quartz ribbons of S<sub>2m</sub>-mylonitic foliation are slightly wrapped around sigmoidal syn-kinematic plagioclase (Ab<sub>76</sub>-Ab<sub>83</sub>) containing a S<sub>i</sub>-foliation. The outermost garnet rim (gros + andr<sub>0.08</sub>, spes<sub>0.07</sub>, pyr<sub>0.05</sub>, alm<sub>0.80</sub>) also grew syn-kinematically with the S<sub>2m</sub>, and indicates a dominant tectonic exhumation into the middle crust (5.5 kbar ≈ 20 km) with a subsequent cooling to 550 °C. A randomly oriented mineral assemblage of andalusite and biotite indicates a subsequent low-pressure (<3 kbar) thermal overprint between 627 ± 24 °C and 664 ± 50 °C, calculated by Ti-in-biotite geothermometers, near the ductile-deformed tonalite pluton. High Y<sub>2</sub>O<sub>3</sub> (>1.5 wt%) homogeneous monazite yielded a Middle Jurassic age (170 ± 4 Ma). Subsequent cooling produced large muscovite laths (Si: ∼3.0 apfu) in metapelites prior to the generation of upward open folds and a S<sub>3</sub>-crenulation cleavage below 500 °C and late low-grade S-C mylonites. Microstructures in minerals indicate high-to low-temperatures solid-state deformation in the igneous and country rocks during the cooling phase. A final retrogression by chlorite and sericite overprinted the metapelites and the intrusive at < 400 °C. The deciphered ẞ-shaped P-T-d path provides constraints on the geotectonic evolution of this particular sector of the North Patagonian Andes, from a Gondwanan subduction setting, followed by exhumation with in","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105216"},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573471","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":"3D stochastic simulation of a deep-water turbidite system: An example from the Los Molles Formation, southern region of the Neuquén Basin, Argentina","authors":"Ariane S. da Silveira ,&nbsp;Márcio Cardoso Jr. ,&nbsp;Paulo S.G. Paim ,&nbsp;José E. Faccion ,&nbsp;Roberto S.F. D’Ávila ,&nbsp;Hector Leanza","doi":"10.1016/j.jsames.2024.105229","DOIUrl":"10.1016/j.jsames.2024.105229","url":null,"abstract":"<div><div>A recurring challenge in geological modeling is bridging the gap between different scales. For example, difficulties arise when connecting outcrop data through production to exploration scale models. An object-based stochastic simulation was performed using outcrop data from the Arroyo La Jardinera area in the southern region of the Neuquén Basin, Argentina. This simulation involved four depositional sequences in a vertical succession that includes turbidites and associated deep marine facies. The aims of this study are (a) to determine the best geological model consistent with field and aerial image data; (b) to validate the application of object modeling to determine facies distribution; (c) to evaluate uncertainties from models based on scarce data. The studied interval covers a transgressive (J1) to regressive succession (J21, J22, and J23) of basin plain to slope depositional settings, featuring sandy and gravelly turbidite channels, turbidite lobes and interlobes, lobe fringes, and muddy slope and basin plain. Each depositional sequence model was constructed using specific input parameters for architectural elements, with lithological proportions based on sedimentary logs. The J1 sequence includes basin plain, lobe fringe, and minor lobe deposits; J21 features turbidite lobes, fringes, and subordinate channels; J22 accommodates turbidite channels scoured into muddy slope facies; and J23 encompasses gravelly and sandy turbidite channels carved on muddy slope facies. The geostatistical modeling of outcrop data has allowed building a quantitative sedimentological model useful for understanding subsurface facies heterogeneity in both exploration (vertical) and production (horizontal) scales.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105229"},"PeriodicalIF":1.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561176","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":"Geophysical evidence for the North Pie de Palo Lineament in the Precordillera","authors":"Federico Lince Klinger ,&nbsp;Marcelo Gonzalez ,&nbsp;Franco Clavel ,&nbsp;María Agostina Grigolo ,&nbsp;Guido Gianni ,&nbsp;Daniel Richarte ,&nbsp;Mario Gimenez","doi":"10.1016/j.jsames.2024.105217","DOIUrl":"10.1016/j.jsames.2024.105217","url":null,"abstract":"<div><div>The Precordillera fold-thrust belt, situated within the Pampean flat-subduction segment (27°–33°S), is characterised by enigmatic transversal structures which extend and influence deformation patterns, the full extent of which is yet to be fully elucidated. The Northern Pie de Palo Lineament represents a key example, and has been proposed to play a pivotal role in the development and structural control of the Precordillera. In any case, this lineament has not been subjected to a comprehensive study, which has led to ongoing debate regarding its structural control, persistence, and morphology. This study was therefore focused on this structure, employing multiple geophysical methodologies, including aeromagnetic and gravimetric techniques. This approach enabled the first visualization of the full extension and fault zone of the North Pie de Palo Lineament, which crosses the entire Precordillera fold-thrust belt in a transverse direction. Consequently, it can be posited that this structure would have exerted a conditioning influence on the thermo-mechanical state of the Andean lithosphere, enabled the uplift of mafic bodies and thus influenced the Neogene deformation of the Precordillera fold and thrust belt. The confirmation and characterization of this major structure open new perspectives on the interaction of deep-seated transversal structures with fold belts during the evolution of the southern central Andes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105217"},"PeriodicalIF":1.7,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578984","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":"Magnetometric and seismic investigation of the Nova Colinas impact structure, Parnaíba Basin, Brazil","authors":"Fernando Lessa Pereira ,&nbsp;Alvaro Penteado Crósta ,&nbsp;Pietro Demattê Avona ,&nbsp;Marcos Alberto Rodrigues Vasconcelos ,&nbsp;Ana Maria Goés","doi":"10.1016/j.jsames.2024.105215","DOIUrl":"10.1016/j.jsames.2024.105215","url":null,"abstract":"<div><div>Nova Colinas (NC) is a complex-type impact structure located in the northeast region of Brazil. It was formed in the volcano-sedimentary strata of the Parnaíba Basin, in the northern part of Western Gondwana. With an apparent diameter of approximately 6.5–7 km, its rim exhibits a distinctive magnetic signal, likely associated to basic volcanic rocks from the Mosquito Formation. These rocks present shock deformation, bracketing the maximum age of the impact event to 197 Ma. We use the magnetometric and seismic methods to establish the geophysical signature of NC and it is the structural framework in subsurface, as well as for characterizing the occurrence and extent of the volcanics. The magnetometric maps present two distinct magnetic domains in the region of NC: (i) the northern area is characterized by short-wavelength magnetic anomalies related to the basaltic flows of the Mosquito Formation; and (ii) the southern region, where sedimentary rocks from the Sambaiba Formation occur, which lacks significant magnetic anomalies, a typical pattern of siliciclastic sedimentary strata. The magnetic sources at the structure's rim reach an estimated depth of ∼250 m, and the position of the rim itself has been effectively established by the total horizontal derivative of the tilt derivative (THDR_TDR) technique. The regional magnetic anomaly suggests a deeper source at the center of the structure, possibly caused by strata with high magnetic susceptibility uplifted in the modification stage of crater formation. Magnetometric modeling using the magnetization vector inversion (MVI) method allowed detailed mapping of the volcanic rocks that form NC's rim. Additionally, analysis of the seismic data allowed the identification of two well-marked horizons, interpreted as diabase sills, located at depths of 600 m and 1200 m, respectively. Impact-related deformation represented by structures such as fractures, a central uplift, and reflector discontinuities associated with faulting, fracturing, and brecciation, were also unveiled by the seismic data, as well as the establishment of the depth of the crystalline basement at ca. 2200 m.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105215"},"PeriodicalIF":1.7,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552641","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":"Jurassic depocenters development, between colorado basin, chelforó sub-basin and neuquén basin","authors":"Emilio A. Rojas Vera,&nbsp;Juan Pablo Lovecchio,&nbsp;Federico Gustavo Enrique Späth,&nbsp;Ofelia Silio,&nbsp;Pedro Kress,&nbsp;Facundo Pagan,&nbsp;Juliana Continanzia,&nbsp;Mirta Suárez,&nbsp;David Giunta,&nbsp;Sebastián Arismendi","doi":"10.1016/j.jsames.2024.105218","DOIUrl":"10.1016/j.jsames.2024.105218","url":null,"abstract":"<div><div>Northern Patagonia, to the north of the Somún Cura Massif along the 39°S parallel, is characterized by the development of a series of Jurassic depocenters, initiating in the Andes to the west, across the Neuquén basin and the Pampean sector (Chelforó sub-basin) towards the Atlantic coast near the location of the Pedro Luro −1 well (onshore Colorado basin), and further east over the Argentine shelf, where multiple Jurassic depocenters form the Colorado, Rawson, and Valdés basins.</div><div>Using marine and continental gravity data (Free air and Isostatic anomalies respectively), constrained by well and seismic data, an integrated interpretation workflow for the study area was carried out. The southern limit of the Neuquén Basin is controlled by the Huincul High, an E-W directed structure with a positive gravimetric anomaly, interpreted as a basement high limited by relative gravimetric lows to the north and south of the structure. The eastern sector includes a series of isolated depocenters, separated by basement highs (obliquely oriented) and limited to the south by the E-W anomaly of the Huincul High. These depocenters correspond to the Chelforó sub-basin, which was drilled in a recent exploration campaign obtaining Jurassic ages where seismic interpretation pointed out presumably Jurassic deposits. Between Valcheta and Sierra Grande, this positive anomaly turns NW and becomes the southern boundary of the Pedro Luro depocenter, partially drilled by the Pedro Luro- 1 well, with possibly Tithonian palynological records at total depth. Between the Pedro Luro depocenter and the Chelforó sub-basin some features consistent with basement highs with circular morphology have been identified on gravimetric data, located in the area limited between the Colorado and Río Negro rivers. Jurassic rift depocenters have also been interpreted further east, in the Colorado basin where depocenters are controlled by an E-W oriented basement high, and further east by NW trending structures near the position of the SDRs (seaward dipping reflectors on the continental-oceanic crust transition zone).</div><div>The common evolution of these Jurassic depocenters is still poorly understood. They extend for more than 1500 km from the Andes to the Atlantic continental shelf and are controlled by structures located to the north of the Somún Cura Massif. The interpretation of seismic lines, and gravimetric data in areas without deep wells allow the identification of new exploration targets increasing the exploration potential of these basins.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105218"},"PeriodicalIF":1.7,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561190","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":"Permian succession from Sierra La Flojera, Sonora, Mexico: Stratigraphy and correlation with Laurentia","authors":"Alejandra Montijo-González ,&nbsp;Francisco Javier Cuen-Romero ,&nbsp;Héctor Arturo Noriega-Ruiz ,&nbsp;Miguel A. Torres-Martínez ,&nbsp;Rogelio Monreal ,&nbsp;Juan J. Avendaño-Pazos ,&nbsp;Blanca Estela Buitrón-Sánchez","doi":"10.1016/j.jsames.2024.105212","DOIUrl":"10.1016/j.jsames.2024.105212","url":null,"abstract":"<div><div>Upper Paleozoic rocks crop out in the central part of Sonora, northwestern Mexico. The Sierra La Flojera, located southeast of Hermosillo City, is an isolated hill with a north-south orientation whose age remains controversial due to the scarcity of well-preserved fossils. However, previous information points out the occurrence of rocks from the Pennsylvanian-Permian and the Upper Triassic (Carnian). This paper focuses on the Permian rocks and describes a stratigraphic succession mainly composed of sandstone, conglomerate, limestone, and fossiliferous limestone with abundant fusulinids, and bryozoan, brachiopod, gastropod, and crinoid remains deposited on a shallow marine shelf. The Permian (early Leonardian) age was determined based on the occurrence of the fusulinids <em>Paraskinnerella</em> sp., <em>Skinnerella</em> sp., and <em>Chalaroschwagerina</em> sp., and <em>Paraschwagerina</em> sp. (reworked), which were associated with crinoid-isolated columnar plates of <em>Preptopremnum</em> cf. <em>laeve</em>. The fossil record studied points out that the Sierra La Flojera section was deposited during the early Leonardian and is coeval with other localities of Sonora, Chihuahua, and Coahuila (Mexico), and California and Texas (USA).</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105212"},"PeriodicalIF":1.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552644","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":"Chronostratigraphy and compositional characteristics of miocene volcanism in the Sierra de Pire Mahuida, extra-Andean Patagonia, Argentina","authors":"Flavia M. Salani ,&nbsp;Joao O. Schneider Santos","doi":"10.1016/j.jsames.2024.105207","DOIUrl":"10.1016/j.jsames.2024.105207","url":null,"abstract":"<div><div>The Pire Mahuida Volcanic Complex (PMVC), located in the extra-Andean region of southern Argentina (68° to 68° 40′W and 41° 51′ to 42° 28′ S), is a bimodal volcanic field that developed during the Miocene (17Ma-14Ma, Langhian-Burdigalian Stages). The complex partially surrounds the southern boundary of the Somún Curá basaltic plateau. The PMVC is mainly composed of acidic pyroclastic and lava facies (rhyolite/dacite flows, lava domes and <em>coulees</em>) and stands out as the one with the largest volume of acid rocks in the Somún Curà province, involving two evolutionary trends (alkaline and subalkaline). Subordinate in volume, basaltic flows overlie this extensive sequence of acidic rocks. Relationships between some units are difficult to establish because they are the result of different eruptive centres. However, stratigraphy, morphology and petrography allow two acid phases to be distinguished, one a mainly lavic phase and the other a mainly pyroclastic phase. U-Pb ages allow precise dating and temporal placement of the acid sequence: 1- lava flows and 2- lava domes and related pyroclastic phases. Two calderas and fissures are responsible for the emission of the felsic rocks. The basaltic facies shows a wide range of characteristics, which also allow two different groups to be distinguished. 1. The basalts of the main plateau are associated with a main fault of NW-SE pattern and 2.The younger basalts are associated with small volcanic edifices. The effusion of the complex was developed in a relatively short time with the basic episode being more prolonged than the acid episode.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105207"},"PeriodicalIF":1.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532230","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":"Coevolution of the holocene coastal barrier and lagoon terraces and their implications on the record of relative sea-level change in southernmost Brazil","authors":"Natália B. Santos ,&nbsp;Ernesto L.C. Lavina ,&nbsp;Paulo S.G. Paim ,&nbsp;Marcelo Kehl de Souza ,&nbsp;Sonia H. Tatumi ,&nbsp;Márcio Yee","doi":"10.1016/j.jsames.2024.105209","DOIUrl":"10.1016/j.jsames.2024.105209","url":null,"abstract":"<div><div>This paper presents the coeval history of a sandy coastal barrier and four lagoon margins located in the Rio Grande do Sul State, southernmost Brazil. To achieve this objective we compared the Holocene relative sea-level changes recorded along a regressive coastal barrier with the register of base-level fluctuations preserved in the lagoon terraces. We used geomorphology, geochronology, geophysics (GPR), and high-resolution sequence stratigraphy to evaluate changes on the relative sea- and base-level recorded in the barrier and lagoon terraces, respectively. The record of the relative sea-level fall (forced regression) began at ∼4 ka in the coastal barrier and around 3.4 ka in the lagoon system. Maximum altitudes of the eolian/beach deposits boundary are similar on both barrier and lagoon settings, hence pointing out that relative sea-level controlled lagoon base-level. The forced regression stage is more accurately preserved in the margin of the lagoons than in the coastal barrier. Along the former, four progradational sets related to stepped terraces record pulses of relative sea-level fall at 3.4, 1.4, 0.35, and 0.27 ka. The pulses that took place from 1.4 ka onwards are recorded as low terraces in the lagoon but appear in the coastal barrier as an acceleration in the rate of the relative sea-level fall. Each relative sea-level fall is supposed to have liberated beach sands for eolian reworking during the subsequent stillstand phase and allowed the development of transgressive dunes. Therefore, we conclude that lagoonal terraces vertical displacements are adequate proxies for high-resolution analysis of relative sea-level changes.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105209"},"PeriodicalIF":1.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142537686","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":"Integration of airborne geophysical data for the characterization of the geothermal system in Valle del Cura, high central Andes","authors":"Franco E. Mancini ,&nbsp;Marcos A. Sánchez ,&nbsp;Silvana Spagnotto ,&nbsp;Gabriela Alvarez ,&nbsp;Florencia Ahumada","doi":"10.1016/j.jsames.2024.105203","DOIUrl":"10.1016/j.jsames.2024.105203","url":null,"abstract":"<div><div>The Valle del Cura region, located in the High Central Andes, over the Pampean flat-slab segment, exhibits several geothermal manifestations suggesting structural rather than magmatic controls. However, the structural and favorable conditions of this geothermal system have not been studied in detail yet. By integrating high-resolution airborne geophysical data with existing geological information using GIS tools, we can better characterize the structural controls of the thermal areas. The application of the upward continuation filter and tilt-angle derivative to the reduced to pole magnetic anomaly map allowed us to delineate structural lineaments that correlate well with known faults in the area. Euler deconvolution successfully identified local structures controlling the subsurface water upwelling and provided reliable depth estimations. Results indicate that the Despoblados area is characterized by NW-oriented deep structural controls reaching depths of up to 5 km. In contrast, the Bañitos-Gollete and the northern thermal areas are controlled by the intersection of N-S with E-W shallow structures at less than 3 km deep. Aeroradiometric data provided additional information for the characterization of several lithological units based on the dominance of radioelements (K, Th and U) in near-surface rocks by using individual and ternary maps. In addition, estimations of radiogenic heat production were crucial for assessing the potential energy of geothermal resources in the region. In particular, higher average values were obtained for igneous and metamorphic basement which may contribute to the geothermal gradient and temperature distribution at depth. Further studies, including new geophysical data acquisition and field verification, are still needed to fully describe the regional and local structures involved in these geothermal areas.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105203"},"PeriodicalIF":1.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573472","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 remains of the enormous hoplophorine glyptodont Uruguayurus Mones, 1987 (Mammalia, Cingulata) in a particular faunistic association, Raigón Formation (Pliocene–middle Pleistocene), Uruguay","authors":"Daniel Perea","doi":"10.1016/j.jsames.2024.105202","DOIUrl":"10.1016/j.jsames.2024.105202","url":null,"abstract":"<div><div>A new specimen of the poorly known glyptodont <em>Uruguayurus</em> Mones, 1987, is described on the basis of a large portion of the caudal tube from Arazatí Harbor, San José Department, Uruguay. This fossil is attributed to the Raigón Formation (Pliocene–middle Pleistocene), which crops out in the coastal cliffs of the referenced locality. This unit shows a particular faunal association characterized by endemic species, other representatives of the South American Cenozoic and others of North American origin. The material described herein shows diagnostic characteristics that allow to consider it an hoplophorine glyptodont, pertaining to the genus referred to above, similar to and the probable descendant from the smaller <em>Pseudoplohophorus</em> Castellanos, 1926, which is abundant in deposits of the underlying Camacho Formation (late Miocene) at the same locality. On the basis of this finding, the knownledge of <em>Uruguayurus</em> is increased and its diagnosis expanded. The new specimen has a larger, flatter, and more symmetrical caudal tube than the specimens previously described, named <em>U. authochthonus</em> Mones1987, and <em>U. lydekkeri</em> (Mones, 1987). It is also distinguished from those morphotypes by having an interapical groove of intermedial width, very large apical and first lateral figures, and more abundant and clearly delimited peripheral figurines on the dorsal surface. For now, these differences could be attributed to intraspecific variations within <em>Uruguayurus authochthonus</em>.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105202"},"PeriodicalIF":1.7,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531675","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}