Pub Date : 2024-10-24DOI: 10.1016/j.jsames.2024.105212
Alejandra Montijo-González , Francisco Javier Cuen-Romero , Héctor Arturo Noriega-Ruiz , Miguel A. Torres-Martínez , Rogelio Monreal , Juan J. Avendaño-Pazos , Blanca Estela Buitrón-Sánchez
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 Paraskinnerella sp., Skinnerella sp., and Chalaroschwagerina sp., and Paraschwagerina sp. (reworked), which were associated with crinoid-isolated columnar plates of Preptopremnum cf. laeve. 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).
{"title":"Permian succession from Sierra La Flojera, Sonora, Mexico: Stratigraphy and correlation with Laurentia","authors":"Alejandra Montijo-González , Francisco Javier Cuen-Romero , Héctor Arturo Noriega-Ruiz , Miguel A. Torres-Martínez , Rogelio Monreal , Juan J. Avendaño-Pazos , 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}
Pub Date : 2024-10-24DOI: 10.1016/j.jsames.2024.105207
Flavia M. Salani , Joao O. Schneider Santos
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 coulees) 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.
{"title":"Chronostratigraphy and compositional characteristics of miocene volcanism in the Sierra de Pire Mahuida, extra-Andean Patagonia, Argentina","authors":"Flavia M. Salani , 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}
Pub Date : 2024-10-24DOI: 10.1016/j.jsames.2024.105209
Natália B. Santos , Ernesto L.C. Lavina , Paulo S.G. Paim , Marcelo Kehl de Souza , Sonia H. Tatumi , Márcio Yee
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.
本文介绍了位于巴西最南端南里奥格兰德州（Rio Grande do Sul）的一个沙质海岸屏障和四个泻湖边缘的共同历史。为了实现这一目标，我们比较了沿回归海岸屏障记录的全新世相对海平面变化和泻湖阶地中保存的基底波动记录。我们利用地貌学、地质年代学、地球物理学（GPR）和高分辨率层序地层学来评估屏障和泻湖阶地分别记录的相对海平面和基底面的变化。沿海屏障的相对海平面下降（强迫回归）记录始于 ∼4 ka，泻湖系统则始于约 3.4 ka。在屏障和泻湖环境中，沉积/海滩沉积边界的最大海拔高度相似，这表明相对海平面控制着泻湖基底面。潟湖边缘比海岸屏障更准确地保留了强迫回归阶段。在前者沿岸，与阶梯阶地有关的四组逐级变化记录了 3.4、1.4、0.35 和 0.27 ka 的相对海平面下降脉冲。从 1.4 ka 开始的脉冲在泻湖中被记录为低阶梯，但在海岸屏障中则表现为海平面相对下降速度的加快。每次海平面相对下降都会释放出海滩沙，以便在随后的静止阶段进行风化再加工，并形成横向沙丘。因此，我们得出结论，泻湖阶地的垂直位移足以作为相对海平面变化高分辨率分析的代用指标。
{"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 , Ernesto L.C. Lavina , Paulo S.G. Paim , Marcelo Kehl de Souza , Sonia H. Tatumi , 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}
Pub Date : 2024-10-24DOI: 10.1016/j.jsames.2024.105203
Franco E. Mancini , Marcos A. Sánchez , Silvana Spagnotto , Gabriela Alvarez , Florencia Ahumada
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.
{"title":"Integration of airborne geophysical data for the characterization of the geothermal system in Valle del Cura, high central Andes","authors":"Franco E. Mancini , Marcos A. Sánchez , Silvana Spagnotto , Gabriela Alvarez , 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}
Pub Date : 2024-10-23DOI: 10.1016/j.jsames.2024.105202
Daniel Perea
A new specimen of the poorly known glyptodont Uruguayurus 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 Pseudoplohophorus 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 Uruguayurus is increased and its diagnosis expanded. The new specimen has a larger, flatter, and more symmetrical caudal tube than the specimens previously described, named U. authochthonus Mones1987, and U. lydekkeri (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 Uruguayurus authochthonus.
{"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}
Pub Date : 2024-10-22DOI: 10.1016/j.jsames.2024.105206
Mónica Ramírez-Calderón , Mélanie Noury , Michelangelo Martini , Luigi Solari , Adolfo Pérez-Estrada
Understanding the exhumation history of ancient orogens is crucial for unraveling the tectonic and climatic forces that shape Earth's landscapes. Relict topography from ancient orogenic belts can persist on the surface for tens of millions of years, providing detritus to surrounding areas even without significant uplift events. This study examines the exhumation history of the Oaxacan Complex in southern Mexico, a Proterozoic peri-Gondwanan continental block located at the periphery of western equatorial Pangea during the l ate Paleozoic. This complex supplied detritus to extensional basins in southern Mexico throughout the Mesozoic and Cenozoic. We reinterpret existing apatite fission track (AFT) data from in situ samples of the Oaxacan Complex and add a set of detrital AFT data from modern sediments of the Peñoles River, which drains the northern Oaxacan Complex. The detrital AFT age distribution is continuous, ranging from ∼180 Ma to ∼50 Ma, without a predominant component age and showing a positive age-elevation correlation, suggesting a slow cooling history of the basement exposed in the drained area. QTQt thermal history modeling of the detrital AFT ages corroborates this slow cooling. Moreover, reinterpretation of in-situ AFT data from the literature confirms that the cooling history of the crustal block exposed in the northern Oaxacan Complex is characterized by a prolonged residence time in the Partial Annealing Zone of the apatite fission-track thermochronometer, spanning at least from the Triassic to the Paleogene. These results suggest that the Oaxacan Complex did not undergo any significant exhumation events after the Late Paleozoic assembly of Pangea, neither during the Triassic–Early Cretaceous rifting associated with Pangea breakup nor during development of the Late Cretaceous–Eocene Mexican Orogen. According to this scenario, we suggest that the post-collision relict topography of the Oaxacan Complex was likely sustained by isostatic rebound and lithological resistance, supplying sediment for tens of millions of years to the Mesozoic and Cenozoic basins of southern Mexico.
{"title":"Long-lived topography of the Oaxacan Complex (southern Mexico) after the assembly of Pangea: Evidence from apatite fission-track dating","authors":"Mónica Ramírez-Calderón , Mélanie Noury , Michelangelo Martini , Luigi Solari , Adolfo Pérez-Estrada","doi":"10.1016/j.jsames.2024.105206","DOIUrl":"10.1016/j.jsames.2024.105206","url":null,"abstract":"<div><div>Understanding the exhumation history of ancient orogens is crucial for unraveling the tectonic and climatic forces that shape Earth's landscapes. Relict topography from ancient orogenic belts can persist on the surface for tens of millions of years, providing detritus to surrounding areas even without significant uplift events. This study examines the exhumation history of the Oaxacan Complex in southern Mexico, a Proterozoic peri-Gondwanan continental block located at the periphery of western equatorial Pangea during the l ate Paleozoic. This complex supplied detritus to extensional basins in southern Mexico throughout the Mesozoic and Cenozoic. We reinterpret existing apatite fission track (AFT) data from in situ samples of the Oaxacan Complex and add a set of detrital AFT data from modern sediments of the Peñoles River, which drains the northern Oaxacan Complex. The detrital AFT age distribution is continuous, ranging from ∼180 Ma to ∼50 Ma, without a predominant component age and showing a positive age-elevation correlation, suggesting a slow cooling history of the basement exposed in the drained area. QTQt thermal history modeling of the detrital AFT ages corroborates this slow cooling. Moreover, reinterpretation of in-situ AFT data from the literature confirms that the cooling history of the crustal block exposed in the northern Oaxacan Complex is characterized by a prolonged residence time in the Partial Annealing Zone of the apatite fission-track thermochronometer, spanning at least from the Triassic to the Paleogene. These results suggest that the Oaxacan Complex did not undergo any significant exhumation events after the Late Paleozoic assembly of Pangea, neither during the Triassic–Early Cretaceous rifting associated with Pangea breakup nor during development of the Late Cretaceous–Eocene Mexican Orogen. According to this scenario, we suggest that the post-collision relict topography of the Oaxacan Complex was likely sustained by isostatic rebound and lithological resistance, supplying sediment for tens of millions of years to the Mesozoic and Cenozoic basins of southern Mexico.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105206"},"PeriodicalIF":1.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532231","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}
Pub Date : 2024-10-22DOI: 10.1016/j.jsames.2024.105205
Jairo Valdati , Arthur Philipe Bechtel , Maria Carolina Villaça Gomes , Yasmim Rizzolli Fontana dos Santos , João Henrique Zahdi Ricetti , Luiz Carlos Weinschütz
The paleoburrows (paleotocas) are ichnofossils produced by the autochthonous megafauna of South America. The Caminhos dos Cânions do Sul UNESCO Global Geopark (CCSUGG), Southern Brazil, contains a large amount of these ichnofossils, which are regarded as internationally relevant. This article aims to discuss paleoburrows as geoheritage and paleoenvironmental records, using the examples present in the CCSUGG. For this purpose, bibliographic research, paleoburrows cataloguing fieldwork and mapping routine were carried out. So far, 24 paleoburrows have been compiled. Mostly found in sedimentary friable rocks, such as the Botucatu Formation sandstones, can also occur in harder, weathered lithologies in a smaller amount. Some bioerosive structures show claw scrapping and digging signs, attributed to the Pliocene-Pleistocene South American megafauna, such as the giant sloths and the giant armadillos. Despite these 24 paleoburrows, four of them are recognized as geosites of regional and international value. These ichnofossils provide geological and paleontological values, considering their builders are already extinct and their presence allows to infer paleoenvironmental changes and megamammals distributions. Besides tangible values, these burrows evoke myths and histories about indigenous people and settlers who used these burrows as shelter, representing intangible cultural heritage. Even though these values, paleoburrows face threats that endanger their conservation, like unguided visitors, water flow and block falls. Hence, there are geoeducational efforts to preserve these ichnofossils for future generations. All these processes are evident in geosites with scientific, scenic and touristic values, the paleotocas giant paleoburrows.
{"title":"More than fossils: Paleoburrows as geoheritage and paleoenvironmental archives in the Caminhos dos Cânions do Sul UNESCO Global Geopark, Southern Brazil","authors":"Jairo Valdati , Arthur Philipe Bechtel , Maria Carolina Villaça Gomes , Yasmim Rizzolli Fontana dos Santos , João Henrique Zahdi Ricetti , Luiz Carlos Weinschütz","doi":"10.1016/j.jsames.2024.105205","DOIUrl":"10.1016/j.jsames.2024.105205","url":null,"abstract":"<div><div>The paleoburrows (<em>paleotocas</em>) are ichnofossils produced by the autochthonous megafauna of South America. The Caminhos dos Cânions do Sul UNESCO Global Geopark (CCSUGG), Southern Brazil, contains a large amount of these ichnofossils, which are regarded as internationally relevant. This article aims to discuss paleoburrows as geoheritage and paleoenvironmental records, using the examples present in the CCSUGG. For this purpose, bibliographic research, paleoburrows cataloguing fieldwork and mapping routine were carried out. So far, 24 paleoburrows have been compiled. Mostly found in sedimentary friable rocks, such as the Botucatu Formation sandstones, can also occur in harder, weathered lithologies in a smaller amount. Some bioerosive structures show claw scrapping and digging signs, attributed to the Pliocene-Pleistocene South American megafauna, such as the giant sloths and the giant armadillos. Despite these 24 paleoburrows, four of them are recognized as geosites of regional and international value. These ichnofossils provide geological and paleontological values, considering their builders are already extinct and their presence allows to infer paleoenvironmental changes and megamammals distributions. Besides tangible values, these burrows evoke myths and histories about indigenous people and settlers who used these burrows as shelter, representing intangible cultural heritage. Even though these values, paleoburrows face threats that endanger their conservation, like unguided visitors, water flow and block falls. Hence, there are geoeducational efforts to preserve these ichnofossils for future generations. All these processes are evident in geosites with scientific, scenic and touristic values, the <em>paleotocas</em> giant paleoburrows.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105205"},"PeriodicalIF":1.7,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561189","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}
Pub Date : 2024-10-18DOI: 10.1016/j.jsames.2024.105204
Diego Brandoni , Javier Soffiantini , Lucas E. Fiorelli , Ernesto Brunetto
The Lower Member of the Ituzaingó Formation (LMIF), fluvial in origin and assigned to the Upper Miocene, contains a conglomerate level known as “Mesopotamiense” or “Conglomerado osífero” that has yielded a rich fauna of vertebrates. The aim of this contribution is to describe a titanosaurian dinosaur eggshell fragment recovered from the LMIF at the locality of Toma Vieja (western Entre Ríos Province), discussing its paleogeographic history and implications. Fragments of eggshells referred to Titanosauria are frequent from litostratigraphic units of the Upper Cretaceous of western Uruguay (e.g., Guichón, Mercedes, and Queguay Formations). Besides, a fragment of eggshell recovered from the Puerto Yeruá Formation (Upper Cretaceous) at eastern Entre Ríos Province was described. Geophysical data from the Entre Ríos Province allow to propose the presence of a Lower Cretaceous field of extensional tectonic stresses that generated structural lineaments with a E-W and ENE-WSW trend. This ancient penetrative Cretaceous tectonic framework would have exerted control on the shape of the basin and sediment flow patterns and subsequent sedimentation, by promoting the generation of accommodation space over the late Paleogene and the Neogene. The phenomenon would have conditioned the deposition of the Fray Bentos Formation, the subsequent marine Paraná Formation, and the sedimentation of the LMIF, with source materials coming from the east. Thus, it is hypothesized that the fragment of eggshell of Titanosauria would come from the eastern area of the basin (western Uruguay) as a consequence of the existence of a paleohydric system with predominantly E-W and ENE-WSW directions. This late Neogene system would have been controlled by inherited Cretaceous structural lineaments with orientations similar to those that also govern the current fluvial systems of western Uruguay, developed on the Mesozoic substrate.
{"title":"Paleogeographic implication of a titanosaur eggshell from the Neogene of the Entre Ríos Province, Argentina","authors":"Diego Brandoni , Javier Soffiantini , Lucas E. Fiorelli , Ernesto Brunetto","doi":"10.1016/j.jsames.2024.105204","DOIUrl":"10.1016/j.jsames.2024.105204","url":null,"abstract":"<div><div>The Lower Member of the Ituzaingó Formation (LMIF), fluvial in origin and assigned to the Upper Miocene, contains a conglomerate level known as “Mesopotamiense” or “Conglomerado osífero” that has yielded a rich fauna of vertebrates. The aim of this contribution is to describe a titanosaurian dinosaur eggshell fragment recovered from the LMIF at the locality of Toma Vieja (western Entre Ríos Province), discussing its paleogeographic history and implications. Fragments of eggshells referred to Titanosauria are frequent from litostratigraphic units of the Upper Cretaceous of western Uruguay (e.g., Guichón, Mercedes, and Queguay Formations). Besides, a fragment of eggshell recovered from the Puerto Yeruá Formation (Upper Cretaceous) at eastern Entre Ríos Province was described. Geophysical data from the Entre Ríos Province allow to propose the presence of a Lower Cretaceous field of extensional tectonic stresses that generated structural lineaments with a E-W and ENE-WSW trend. This ancient penetrative Cretaceous tectonic framework would have exerted control on the shape of the basin and sediment flow patterns and subsequent sedimentation, by promoting the generation of accommodation space over the late Paleogene and the Neogene. The phenomenon would have conditioned the deposition of the Fray Bentos Formation, the subsequent marine Paraná Formation, and the sedimentation of the LMIF, with source materials coming from the east. Thus, it is hypothesized that the fragment of eggshell of Titanosauria would come from the eastern area of the basin (western Uruguay) as a consequence of the existence of a paleohydric system with predominantly E-W and ENE-WSW directions. This late Neogene system would have been controlled by inherited Cretaceous structural lineaments with orientations similar to those that also govern the current fluvial systems of western Uruguay, developed on the Mesozoic substrate.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105204"},"PeriodicalIF":1.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532228","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}
Pub Date : 2024-10-18DOI: 10.1016/j.jsames.2024.105200
Johanset Orihuela , Lázaro W. Viñola-Lopez , Logel Lorenzo , Alberto Clark , Yasmani Ceballos-Izquierdo
<div><div>Here we report new land vertebrate fossils from the El Abra outcrop in Matanzas, Western Cuba, offering key insights into the Late Pliocene-Early Pleistocene Greater Antillean mammal fossil record. The paucity of documented terrestrial mammal fossils in this interval has hindered a more comprehensive understanding of their evolutionary histories. The discovery of previously undocumented capromyine rodent dental remains provides a significant enrichment to the Cuban land vertebrate fossil record. One notable specimen, a capromyine molar, displays an occlusal pattern characteristic of genera such as <em>Mesocapromys</em>, <em>Mysateles</em>, <em>Macrocapromys</em>, <em>Capromys</em>, and <em>Geocapromys</em>, as well as the Hispaniolan <em>Hexolobodon</em>. While these genera form a monophyletic clade that radiated during the Pliocene-Pleistocene, typically marked by molars with open roots, the El Abra specimen shows partially closed roots, a feature not previously observed in Cuban taxa, suggesting potential affinities with <em>Hexolobodon</em>. Other <em>incertae sedis</em> mammals are represented by fragmentary long bone diaphyses with evidence of transportation. Microfossil assemblages indicate reworking, with taxa spanning from the Late Cretaceous to the earliest Pleistocene. Preliminary foraminiferal biostratigraphy and <sup>87</sup>Sr/<sup>86</sup>Sr isotope analysis support a depositional age between the latest Pliocene and earliest Pleistocene. However, while the exact age of these new terrestrial vertebrate fossils remain uncertain for lack of direct, absolute dating, we approximate their age based on the estimated chronology. These fossils are likely diachronic and could be potentially older. These findings suggest complex patterns of vertebrate dispersal and diversification in the Caribbean. The findings highlight complex biogeographic patterns of vertebrate dispersal and diversification across the Caribbean. Addressing these historical biodiversity patterns is critical, as the combination of recent extinctions and gaps in the fossil record may obscure a true understanding of past species richness and evolutionary processes within the insular Caribbean.</div><div>Resumen</div><div>Aquí reportamos nuevos fósiles de vertebrados terrestres del afloramiento El Abra en Matanzas, Cuba occidental, que ofrecen relevante información sobre el registro fósil de mamíferos de las Antillas Mayores durante el Plioceno Tardío-Pleistoceno Temprano. La escasez de fósiles documentados de mamíferos terrestres en este intervalo ha obstaculizado una comprensión más completa de sus historias evolutivas y diversidad. El descubrimiento de restos dentales previamente no documentados de roedores representa un enriquecimiento del registro fósil de vertebrados terrestres de Cuba. Un espécimen notable, un molar de capromyinae, exhibe un patrón oclusal característico de géneros como <em>Mesocapromys</em>, <em>Mysateles</em>, <em>Macrocapromys</em>, <em>Capr
{"title":"First record of terrestrial vertebrates from a Late Pliocene-Early Pleistocene deposit in Cuba","authors":"Johanset Orihuela , Lázaro W. Viñola-Lopez , Logel Lorenzo , Alberto Clark , Yasmani Ceballos-Izquierdo","doi":"10.1016/j.jsames.2024.105200","DOIUrl":"10.1016/j.jsames.2024.105200","url":null,"abstract":"<div><div>Here we report new land vertebrate fossils from the El Abra outcrop in Matanzas, Western Cuba, offering key insights into the Late Pliocene-Early Pleistocene Greater Antillean mammal fossil record. The paucity of documented terrestrial mammal fossils in this interval has hindered a more comprehensive understanding of their evolutionary histories. The discovery of previously undocumented capromyine rodent dental remains provides a significant enrichment to the Cuban land vertebrate fossil record. One notable specimen, a capromyine molar, displays an occlusal pattern characteristic of genera such as <em>Mesocapromys</em>, <em>Mysateles</em>, <em>Macrocapromys</em>, <em>Capromys</em>, and <em>Geocapromys</em>, as well as the Hispaniolan <em>Hexolobodon</em>. While these genera form a monophyletic clade that radiated during the Pliocene-Pleistocene, typically marked by molars with open roots, the El Abra specimen shows partially closed roots, a feature not previously observed in Cuban taxa, suggesting potential affinities with <em>Hexolobodon</em>. Other <em>incertae sedis</em> mammals are represented by fragmentary long bone diaphyses with evidence of transportation. Microfossil assemblages indicate reworking, with taxa spanning from the Late Cretaceous to the earliest Pleistocene. Preliminary foraminiferal biostratigraphy and <sup>87</sup>Sr/<sup>86</sup>Sr isotope analysis support a depositional age between the latest Pliocene and earliest Pleistocene. However, while the exact age of these new terrestrial vertebrate fossils remain uncertain for lack of direct, absolute dating, we approximate their age based on the estimated chronology. These fossils are likely diachronic and could be potentially older. These findings suggest complex patterns of vertebrate dispersal and diversification in the Caribbean. The findings highlight complex biogeographic patterns of vertebrate dispersal and diversification across the Caribbean. Addressing these historical biodiversity patterns is critical, as the combination of recent extinctions and gaps in the fossil record may obscure a true understanding of past species richness and evolutionary processes within the insular Caribbean.</div><div>Resumen</div><div>Aquí reportamos nuevos fósiles de vertebrados terrestres del afloramiento El Abra en Matanzas, Cuba occidental, que ofrecen relevante información sobre el registro fósil de mamíferos de las Antillas Mayores durante el Plioceno Tardío-Pleistoceno Temprano. La escasez de fósiles documentados de mamíferos terrestres en este intervalo ha obstaculizado una comprensión más completa de sus historias evolutivas y diversidad. El descubrimiento de restos dentales previamente no documentados de roedores representa un enriquecimiento del registro fósil de vertebrados terrestres de Cuba. Un espécimen notable, un molar de capromyinae, exhibe un patrón oclusal característico de géneros como <em>Mesocapromys</em>, <em>Mysateles</em>, <em>Macrocapromys</em>, <em>Capr","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"149 ","pages":"Article 105200"},"PeriodicalIF":1.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142532232","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}
Pub Date : 2024-10-18DOI: 10.1016/j.jsames.2024.105201
Juan I. Falco , Rodrigo J. Suárez , Natalia Hauser , Claudia B. Zaffarana , Nicolas Scivetti , Wolf Uwe Reimold , Andrés Folguera
The geodynamic setting across the Paleozoic to Mesozoic transition in Patagonia and the Antarctic Peninsula (SW Pangea) has been strongly debated. Hypotheses of terrane accretion, episodes of shallower to flattened subduction, long-lived stages of crustal extension, or even subduction arrest have been variably proposed. We have compiled and re-evaluated the available whole-rock geochemistry and zircon Hf-isotope data for Permian to Triassic rocks from Patagonia and the Antarctic Peninsula, and compared these findings with the orogenic events in these regions.
We have identified that two orogenic cycles occurred along the SW margin of Pangea during the Permian-Triassic interval, namely the Gondwanide and Chonide/Peninsula orogenies. Both orogenies coexisted with the development of magmatic arcs; the Permian arc exhibits an overall I-type signature that switched to A-type towards ca. 252 Ma, whereas the Triassic arc has an S-type signature in the Antarctic Peninsula and intraplate features in Patagonia. The Hf isotope data for zircon exhibit broadly subchondritic values, suggesting significant crustal contribution in the magmatic source during both cycles. The short- and long-term temporal behavior of the isotopic trends suggests variations that may be attributable to the participation of primitive and/or evolved sources. We conclude that the geochemical and isotopic signatures of the magmas, together with different styles of crustal deformation, resulted from the interaction of the upper and lower plates, consistent with the evolution of an accretionary-type margin along SW Pangea during Permian and Triassic times.
关于巴塔哥尼亚和南极半岛（西南泛大陆）从古生代向中生代过渡的地球动力环境，一直存在着激烈的争论。人们提出了不同的假设：地层增生、从较浅到扁平的俯冲、地壳延伸的长期阶段，甚至是俯冲停止。我们汇编并重新评估了巴塔哥尼亚和南极半岛二叠纪至三叠纪岩石的现有全岩地球化学和锆石Hf-同位素数据，并将这些发现与这些地区的造山运动事件进行了比较。这两次造山运动都与岩浆弧的发展并存；二叠纪岩浆弧呈现出整体的 I 型特征，在大约 252 Ma 时转为 A 型特征，而三叠纪岩浆弧在南极半岛和巴塔哥尼亚的板块内特征为 S 型特征。锆石的 Hf 同位素数据显示出广泛的亚软玉值，表明在这两个周期中岩浆源都有大量的地壳贡献。同位素趋势的短期和长期时间行为表明，原始和/或演化源的参与可能会造成变化。我们的结论是，岩浆的地球化学和同位素特征以及不同的地壳变形方式是上下板块相互作用的结果，与二叠纪和三叠纪期间沿潘加西南部的增生型边缘的演化相一致。
{"title":"The Permian to late Triassic magmatic evolution of SW Pangea: Reconciling evidence from Patagonia and the Antarctic Peninsula","authors":"Juan I. Falco , Rodrigo J. Suárez , Natalia Hauser , Claudia B. Zaffarana , Nicolas Scivetti , Wolf Uwe Reimold , Andrés Folguera","doi":"10.1016/j.jsames.2024.105201","DOIUrl":"10.1016/j.jsames.2024.105201","url":null,"abstract":"<div><div>The geodynamic setting across the Paleozoic to Mesozoic transition in Patagonia and the Antarctic Peninsula (SW Pangea) has been strongly debated. Hypotheses of terrane accretion, episodes of shallower to flattened subduction, long-lived stages of crustal extension, or even subduction arrest have been variably proposed. We have compiled and re-evaluated the available whole-rock geochemistry and zircon Hf-isotope data for Permian to Triassic rocks from Patagonia and the Antarctic Peninsula, and compared these findings with the orogenic events in these regions.</div><div>We have identified that two orogenic cycles occurred along the SW margin of Pangea during the Permian-Triassic interval, namely the Gondwanide and Chonide/Peninsula orogenies. Both orogenies coexisted with the development of magmatic arcs; the Permian arc exhibits an overall I-type signature that switched to A-type towards <em>ca</em>. 252 Ma, whereas the Triassic arc has an S-type signature in the Antarctic Peninsula and intraplate features in Patagonia. The Hf isotope data for zircon exhibit broadly subchondritic values, suggesting significant crustal contribution in the magmatic source during both cycles. The short- and long-term temporal behavior of the isotopic trends suggests variations that may be attributable to the participation of primitive and/or evolved sources. We conclude that the geochemical and isotopic signatures of the magmas, together with different styles of crustal deformation, resulted from the interaction of the upper and lower plates, consistent with the evolution of an accretionary-type margin along SW Pangea during Permian and Triassic times.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"150 ","pages":"Article 105201"},"PeriodicalIF":1.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657995","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}
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