Pub Date : 2025-12-18DOI: 10.1016/j.jsames.2025.105921
Michele Iemma, Vinicius Carneiro, André Gondim Brandão, João Paulo Oliveira, Leonardo Borghi
In the distal southern Campos Basin, the reservoirs consist of pre-salt carbonates (Macabu Fm.), which underwent successive diagenetic processes such as silicification and dolomitization. These processes are responsible for changing the original mineral composition as well as their pore system categorized into matrix and non-matrix features. Therefore, advanced techniques such as Artificial Intelligence (AI) and related methodologies have been increasingly applied to improve the prediction of reservoir characteristics. This study aims to use open-hole wireline logs and borehole image logs (BHI) from six wells in the BM-C-33 block to investigate the distribution of non-matrix features and permeability–porosity properties, across mineralogical (calcite, dolomite, silica and clay) and reservoir facies of the Macabu Formation carbonates. The study's findings reveal a notable prevalence of silicified carbonates interbedded with restricted dolomitized layers. These highly silicified intervals exhibit a higher fracture density, with a mean P10 of around 3 fractures/m. Petrophysical models indicate average porosity and permeability values of 9 % and 0.34 mD, respectively among the six wells. The highest values occur in silicified carbonates, contrasting with the lower ones observed in dolomitized intervals. Overall the study suggest a certain favoring of the silicification process in the quality of the reservoirs.
{"title":"Linking mineralogical facies, petrophysical properties, and non-matrix features in silicified carbonates, BM-C-33, Campos Basin","authors":"Michele Iemma, Vinicius Carneiro, André Gondim Brandão, João Paulo Oliveira, Leonardo Borghi","doi":"10.1016/j.jsames.2025.105921","DOIUrl":"10.1016/j.jsames.2025.105921","url":null,"abstract":"<div><div>In the distal southern Campos Basin, the reservoirs consist of pre-salt carbonates (Macabu Fm.), which underwent successive diagenetic processes such as silicification and dolomitization. These processes are responsible for changing the original mineral composition as well as their pore system categorized into matrix and non-matrix features. Therefore, advanced techniques such as Artificial Intelligence (AI) and related methodologies have been increasingly applied to improve the prediction of reservoir characteristics. This study aims to use open-hole wireline logs and borehole image logs (BHI) from six wells in the BM-C-33 block to investigate the distribution of non-matrix features and permeability–porosity properties, across mineralogical (calcite, dolomite, silica and clay) and reservoir facies of the Macabu Formation carbonates. The study's findings reveal a notable prevalence of silicified carbonates interbedded with restricted dolomitized layers. These highly silicified intervals exhibit a higher fracture density, with a mean P10 of around 3 fractures/m. Petrophysical models indicate average porosity and permeability values of 9 % and 0.34 mD, respectively among the six wells. The highest values occur in silicified carbonates, contrasting with the lower ones observed in dolomitized intervals. Overall the study suggest a certain favoring of the silicification process in the quality of the reservoirs.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"171 ","pages":"Article 105921"},"PeriodicalIF":1.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145841810","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 : 2025-12-18DOI: 10.1016/j.jsames.2025.105922
I.A. Petrinovic , I.R. Hernando , J. Martí Molist
The Caviahue caldera represents one of the largest topographic depressions identified in the Southern Volcanic Zone of the Andes. Here we present volcanological, stratigraphic, geochronological, and structural data of the Caviahue caldera, complemented by available subsurface information. These data support the interpretation of two caldera collapse cycles: the first at 1.27 Ma (Caviahue Caldera) and the second at 0.134 Ma (Las Mellizas Caldera). Both cycles are predominantly intermediate in composition and share several key features, including the formation of multiple lava vents, widespread deposition of ignimbrite and lava sheets associated with caldera collapse, and inter-eruptive epiclastic sedimentation. The 1.27 Ma Caviahue caldera did not result from a single, catastrophic collapse event, but from incremental collapses driven by substantial lava effusion episodes similar to those observed in mafic calderas, interspersed with explosive events characteristic of silicic systems.
The Las Mellizas caldera, dated at 0.134 Ma, began with pre-caldera lava flows and syn-to inter-eruptive sedimentation within deltaic, fluvial, and alluvial settings related to a glacial environment. This was followed by a single ignimbritic eruption accompanying caldera collapse, concluding with the growth of the post-caldera Copahue volcano.
Both caldera collapse cycles show evidence of interactions between effusive and explosive volcanism and glacial conditions, as recorded in both volcanic and sedimentary deposits. This indicates the presence and persistence of glaciations in the Southern Andes prior to 1.27 Ma. The pattern of incremental caldera collapse, characterized by both effusive and explosive activity within glaciated environments, may represent a defining feature of calderas in the Southern Volcanic Zone.
卡维亚休火山口代表了安第斯山脉南部火山带中最大的地形洼地之一。在这里，我们提供了火山学、地层学、地质年代学和Caviahue火山口的结构数据，并辅以现有的地下信息。这些数据支持对两个火山口崩塌周期的解释：第一个在1.27 Ma (Caviahue caldera)，第二个在0.134 Ma （Las Mellizas caldera）。这两个旋回的主要成分都是中等的，并具有几个关键特征，包括多个熔岩喷口的形成，与火山口崩塌相关的火成岩和熔岩板的广泛沉积，以及喷发间的碎屑沉积。1.27 Ma Caviahue火山口不是由单一的灾难性崩塌事件造成的，而是由大量熔岩流出事件驱动的渐进式崩塌造成的，类似于在基性火山口中观察到的，其间穿插着硅系特征的爆炸事件。Las Mellizas火山口的年代为0.134 Ma，开始于火山口前的熔岩流和与冰川环境相关的三角洲，河流和冲积环境中的同期喷发间沉积。随后是一次火成岩喷发，伴随着火山口的崩塌，最后形成了后火山口的科帕韦火山。两个破火山口崩塌旋回都显示了火山喷发和火山爆发与冰川条件之间相互作用的证据，这些都记录在火山和沉积物中。这表明在1.27 Ma之前，南安第斯山脉存在并持续着冰川作用。在冰川环境中，以喷涌和爆炸活动为特征的增量破火山口崩塌模式可能代表了南部火山岩带破火山口的一个决定性特征。
{"title":"Geological and volcanological constraints on a long-lived and multi-stage collapse caldera: The Caviahue caldera, southern volcanic zone of the Andes","authors":"I.A. Petrinovic , I.R. Hernando , J. Martí Molist","doi":"10.1016/j.jsames.2025.105922","DOIUrl":"10.1016/j.jsames.2025.105922","url":null,"abstract":"<div><div>The Caviahue caldera represents one of the largest topographic depressions identified in the Southern Volcanic Zone of the Andes. Here we present volcanological, stratigraphic, geochronological, and structural data of the Caviahue caldera, complemented by available subsurface information. These data support the interpretation of two caldera collapse cycles: the first at 1.27 Ma (Caviahue Caldera) and the second at 0.134 Ma (Las Mellizas Caldera). Both cycles are predominantly intermediate in composition and share several key features, including the formation of multiple lava vents, widespread deposition of ignimbrite and lava sheets associated with caldera collapse, and inter-eruptive epiclastic sedimentation. The 1.27 Ma Caviahue caldera did not result from a single, catastrophic collapse event, but from incremental collapses driven by substantial lava effusion episodes similar to those observed in mafic calderas, interspersed with explosive events characteristic of silicic systems.</div><div>The Las Mellizas caldera, dated at 0.134 Ma, began with pre-caldera lava flows and syn-to inter-eruptive sedimentation within deltaic, fluvial, and alluvial settings related to a glacial environment. This was followed by a single ignimbritic eruption accompanying caldera collapse, concluding with the growth of the post-caldera Copahue volcano.</div><div>Both caldera collapse cycles show evidence of interactions between effusive and explosive volcanism and glacial conditions, as recorded in both volcanic and sedimentary deposits. This indicates the presence and persistence of glaciations in the Southern Andes prior to 1.27 Ma. The pattern of incremental caldera collapse, characterized by both effusive and explosive activity within glaciated environments, may represent a defining feature of calderas in the Southern Volcanic Zone.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"171 ","pages":"Article 105922"},"PeriodicalIF":1.5,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145841809","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 : 2025-12-15DOI: 10.1016/j.jsames.2025.105920
Uilliams Alves de Oliveira Paz , Luis Felipe Ferreira de Mendonça , Arthur Antônio Machado
Topographic irregularities act as mechanisms of flow convergence or divergence, affecting the vertical distribution of motion and creating velocity gradients. In estuarine regions, this process favors the formation of persistent residual structures, which play the role of concentrating or dispersing matter. This study investigates spatial variations in estuarine tidal flow induced by bathymetric variations on scales of 1–70 m, using Acoustic Doppler Current Profilers (ADCP). ADCP results show that in channels near Frades Island, bathymetric deepening generates more intense flows, with velocities reaching 0.6 m/s northward in the meridional component and 0.8 m/s westward in the zonal component, consistent with three-dimensional fluid dynamics. In regions farther from the mainland, bathymetric deepening causes attenuation and reversal of currents. Near to Itaparica Island, bathymetry deepens from 15 m to 50 m over a 2 km stretch, with the meridional component showing a variation from 0.4 m/s northward to 0.7 m/s southward. In the center of BTS, the reversal of the zonal component leads to the formation of cyclonic vortices. The ADCP data show that deepening in confined regions accelerates the flow, while in open areas it decelerates the flow, occasionally creating recirculation zones and localized vorticity. These results corroborate the existing literature on the influence of bathymetry on estuarine circulation and provide in situ evidence, highlighting the importance of incorporating high-resolution bathymetry and stratification to reproduce the complexity of flow in estuarine regions.
{"title":"Influence of bathymetric variation on the flows of Baía de Todos os Santos","authors":"Uilliams Alves de Oliveira Paz , Luis Felipe Ferreira de Mendonça , Arthur Antônio Machado","doi":"10.1016/j.jsames.2025.105920","DOIUrl":"10.1016/j.jsames.2025.105920","url":null,"abstract":"<div><div>Topographic irregularities act as mechanisms of flow convergence or divergence, affecting the vertical distribution of motion and creating velocity gradients. In estuarine regions, this process favors the formation of persistent residual structures, which play the role of concentrating or dispersing matter. This study investigates spatial variations in estuarine tidal flow induced by bathymetric variations on scales of 1–70 m, using Acoustic Doppler Current Profilers (ADCP). ADCP results show that in channels near Frades Island, bathymetric deepening generates more intense flows, with velocities reaching 0.6 m/s northward in the meridional component and 0.8 m/s westward in the zonal component, consistent with three-dimensional fluid dynamics. In regions farther from the mainland, bathymetric deepening causes attenuation and reversal of currents. Near to Itaparica Island, bathymetry deepens from 15 m to 50 m over a 2 km stretch, with the meridional component showing a variation from 0.4 m/s northward to 0.7 m/s southward. In the center of BTS, the reversal of the zonal component leads to the formation of cyclonic vortices. The ADCP data show that deepening in confined regions accelerates the flow, while in open areas it decelerates the flow, occasionally creating recirculation zones and localized vorticity. These results corroborate the existing literature on the influence of bathymetry on estuarine circulation and provide in situ evidence, highlighting the importance of incorporating high-resolution bathymetry and stratification to reproduce the complexity of flow in estuarine regions.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"171 ","pages":"Article 105920"},"PeriodicalIF":1.5,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145799274","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 : 2025-12-13DOI: 10.1016/j.jsames.2025.105919
Ramón Yosvanis Batista Cruz , Yuri Almaguer Carmenates , José Alberto Batista Rodríguez , Felipe de Jesús López Saucedo , Yalina Montecelos Zamora , Brenda Margarita Salas Ramos , Aylin Karel Ibarra Torres , Frida García Robles , Luis Eutiquio Canales Gutiérrez
The hydrogeological potential of Coahuila, Northeast Mexico, is evaluated through an integrated approach that combines cartographic datasets, bibliometric analysis, and a GIS-based assessment of 1912 groundwater points distributed across 28 aquifers. Beyond synthesizing existing regional knowledge, this study introduces a comprehensive methodological framework that links geological, hydrological, and socio-economic dimensions through 18 thematic GIS layers, offering a spatially explicit understanding of the key factors controlling groundwater availability and quality. The bibliometric evaluation also provides the first systematic diagnosis of water-related scientific production in Coahuila, revealing a significant disconnect between local research output and the state's critical water-management challenges. The results indicate that extensive carbonate formations, enhanced by karst processes (e.g., the Cupido, Aurora, Glen Rose, and Edwards formations), constitute the most productive aquifer units, while stratigraphic heterogeneity and local tectonics exert strong controls on permeability, compartmentalization, and groundwater flow. Geomorphological and hydrological conditions further shape the distribution of wells: nearly three-quarters are concentrated in plains and piedmont slopes; whereas, mountain ranges function as primary recharge zones in an arid to semi-arid climate. Hydrological indices, including the Topographic Wetness Index and catchment coefficients, refine the interpretation of recharge-discharge dynamics and explain the high well densities found in lowland basins, which are more vulnerable to salinity and sulfate enrichment. Socio-economic drivers, such as accessibility and population density, also influence drilling patterns. However, groundwater quality remains a major constraint, with widespread salinity and excessive sulfate and heavy-metal contamination being particularly associated with the evaporitic La Virgen Formation (and other hydrogeologically unfavorable lithologies), frequently compromising water suitability. Overall, this study provides a novel, integrated framework that strengthens the scientific basis for groundwater evaluation and offers actionable insights to support more-informed and sustainable water-resource management in Coahuila.
{"title":"Hydrogeological suitability of Coahuila, Northeast Mexico: An integrated bibliometric, GIS, and water quality assessment","authors":"Ramón Yosvanis Batista Cruz , Yuri Almaguer Carmenates , José Alberto Batista Rodríguez , Felipe de Jesús López Saucedo , Yalina Montecelos Zamora , Brenda Margarita Salas Ramos , Aylin Karel Ibarra Torres , Frida García Robles , Luis Eutiquio Canales Gutiérrez","doi":"10.1016/j.jsames.2025.105919","DOIUrl":"10.1016/j.jsames.2025.105919","url":null,"abstract":"<div><div>The hydrogeological potential of Coahuila, Northeast Mexico, is evaluated through an integrated approach that combines cartographic datasets, bibliometric analysis, and a GIS-based assessment of 1912 groundwater points distributed across 28 aquifers. Beyond synthesizing existing regional knowledge, this study introduces a comprehensive methodological framework that links geological, hydrological, and socio-economic dimensions through 18 thematic GIS layers, offering a spatially explicit understanding of the key factors controlling groundwater availability and quality. The bibliometric evaluation also provides the first systematic diagnosis of water-related scientific production in Coahuila, revealing a significant disconnect between local research output and the state's critical water-management challenges. The results indicate that extensive carbonate formations, enhanced by karst processes (e.g., the Cupido, Aurora, Glen Rose, and Edwards formations), constitute the most productive aquifer units, while stratigraphic heterogeneity and local tectonics exert strong controls on permeability, compartmentalization, and groundwater flow. Geomorphological and hydrological conditions further shape the distribution of wells: nearly three-quarters are concentrated in plains and piedmont slopes; whereas, mountain ranges function as primary recharge zones in an arid to semi-arid climate. Hydrological indices, including the Topographic Wetness Index and catchment coefficients, refine the interpretation of recharge-discharge dynamics and explain the high well densities found in lowland basins, which are more vulnerable to salinity and sulfate enrichment. Socio-economic drivers, such as accessibility and population density, also influence drilling patterns. However, groundwater quality remains a major constraint, with widespread salinity and excessive sulfate and heavy-metal contamination being particularly associated with the evaporitic La Virgen Formation (and other hydrogeologically unfavorable lithologies), frequently compromising water suitability. Overall, this study provides a novel, integrated framework that strengthens the scientific basis for groundwater evaluation and offers actionable insights to support more-informed and sustainable water-resource management in Coahuila.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105919"},"PeriodicalIF":1.5,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145847573","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 : 2025-12-12DOI: 10.1016/j.jsames.2025.105912
Beatriz Coira , Suzanne Mahlburg Kay
This paper presents an updated review and discussion of the mining potential of ore and geothermal deposits related to Cenozoic volcanism in the Central Andean Puna. The types and distributions of these systems reflect the volcanic, structural and geophysical conditions at the time of formation. Most are related to volcanism in a thickening continental crust over a shallowing or steepening subduction zone.
The most important Cenozoic mineralization periods were at 33–28.7 Ma, 16-11 Ma and 10-6 Ma. The first produced the early Miocene Cu-Mo-Au porphyries in the southern Puna, the second the middle Miocene Cu-Mo and Au-Cu porphyries related to epithermal systems with Pb and Zn (+Ag ± Sn) in dome complexes in the northern and southern Puna, and the third the base metal Ag-rich veined epithermal deposits in composite volcanoes related to megacalderas with post collapse vetiform epithermal base metals and high Ag/Au ratios and Sb, Sn and Bi anomalies.
Most northern Puna (22°S-24°30′S) ore deposits are in Pb-Zn (+Ag-Sn) epithermal systems whose metallogenetic signatures are like coeval Bolivian Tin Belt deposits. In contrast, most southern Puna deposits (∼24.5°- 27°S) are in porphyry type Cu-Mo, Cu-Au and Pb + Zn ± Ag + Cu ± Au epithermal systems. These differences reflect both tectonic conditions and the nature of the underlying crust.
The most promising geothermal prospects are in the Puna where they are intimately linked with young volcanic centers associated with heat anomalies in the crust related to partial melt zones. Prominent high enthalpy prospects are in the Tuzgle, Tocomar, Cerro Blanco and Cerro Galán regions where Quaternary heat anomalies reflect partial melt zones. Advanced feasibility studies exist in the Tuzgle and Tocomar systems.
{"title":"Relation of Cenozoic volcanism, mineral deposits and geothermal resources in the Puna to the geologic evolution of the Southern Central Andes (22°-28°S)","authors":"Beatriz Coira , Suzanne Mahlburg Kay","doi":"10.1016/j.jsames.2025.105912","DOIUrl":"10.1016/j.jsames.2025.105912","url":null,"abstract":"<div><div>This paper presents an updated review and discussion of the mining potential of ore and geothermal deposits related to Cenozoic volcanism in the Central Andean Puna. The types and distributions of these systems reflect the volcanic, structural and geophysical conditions at the time of formation. Most are related to volcanism in a thickening continental crust over a shallowing or steepening subduction zone.</div><div>The most important Cenozoic mineralization periods were at 33–28.7 Ma, 16-11 Ma and 10-6 Ma. The first produced the early Miocene Cu-Mo-Au porphyries in the southern Puna, the second the middle Miocene Cu-Mo and Au-Cu porphyries related to epithermal systems with Pb and Zn (+Ag ± Sn) in dome complexes in the northern and southern Puna, and the third the base metal Ag-rich veined epithermal deposits in composite volcanoes related to megacalderas with post collapse vetiform epithermal base metals and high Ag/Au ratios and Sb, Sn and Bi anomalies.</div><div>Most northern Puna (22°S-24°30′S) ore deposits are in Pb-Zn (+Ag-Sn) epithermal systems whose metallogenetic signatures are like coeval Bolivian Tin Belt deposits. In contrast, most southern Puna deposits (∼24.5°- 27°S) are in porphyry type Cu-Mo, Cu-Au and Pb + Zn ± Ag + Cu ± Au epithermal systems. These differences reflect both tectonic conditions and the nature of the underlying crust.</div><div>The most promising geothermal prospects are in the Puna where they are intimately linked with young volcanic centers associated with heat anomalies in the crust related to partial melt zones. Prominent high enthalpy prospects are in the Tuzgle, Tocomar, Cerro Blanco and Cerro Galán regions where Quaternary heat anomalies reflect partial melt zones. Advanced feasibility studies exist in the Tuzgle and Tocomar systems.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"172 ","pages":"Article 105912"},"PeriodicalIF":1.5,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886266","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 : 2025-12-10DOI: 10.1016/j.jsames.2025.105918
C. Montes , C.A. Rosero , F. Lamus , L.C. Perez-Angel , G. Bayona , J.M. Muñoz
A ∼23 km-long, hiking-kayaking, panoramic transect along the Rionegro Canyon in the western flank of the Eastern Cordillera of Colombia reveals two deformed belts with contrasting structural styles separated by a regional fault (La Salina Thrust). East of the fault, a deformed belt is characterized by tight, horizontal and upright concentric and box folds with pervasive axial-planar cleavage within a Lower Cretaceous, mostly sandy sequence. West the fault, the structural style is characterized by thrust sheets with prominent footwall deformation and isoclinal folding in the hanging wall. At least four stacked thrust sheets that repeat Upper Cretaceous sequences define a regional-scale duplex (El Trigo-Bituima anticlinal stack duplex). Immediately west of the anticlinal duplex, a regional syncline (Guaduas) folds a ∼1.5 km-thick, middle Eocene to Oligocene molasse deposit. The western flank of the syncline is thrusted (Cambras Thrust) on to a ∼2 km-thick Miocene molasse deposit repeated by the frontal thrust of the Eastern Cordillera (Honda Thrust). Line-balancing of a 30 km-long cross-section that includes the Honda Thrust results in a shortening value of ∼60 % (∼45 km) not considering layer-parallel shortening. Reconstruction of the original geometry suggests the presence of two rift-fault systems: one to the east, where the thickness of Cretaceous sequence changes from ∼4 to 3 km, and another one ∼50 km to the west, where the ∼3 km-thick Cretaceous sequence thins to nothing. The former is reactivated as the La Salina Thrust and likely contains pre-Cretaceous basement rocks in its hanging wall, and the latter is not reactivated, as previous studies had proposed. All of this is consistent with a main pulse of growth of the Eastern Cordillera and major surface elevation gain starting in middle Eocene times.
{"title":"Panoramic Transect of the Western Flank of Eastern Cordillera Fold and Thrust Belt, Northern Andes, Colombia","authors":"C. Montes , C.A. Rosero , F. Lamus , L.C. Perez-Angel , G. Bayona , J.M. Muñoz","doi":"10.1016/j.jsames.2025.105918","DOIUrl":"10.1016/j.jsames.2025.105918","url":null,"abstract":"<div><div>A ∼23 km-long, hiking-kayaking, panoramic transect along the Rionegro Canyon in the western flank of the Eastern Cordillera of Colombia reveals two deformed belts with contrasting structural styles separated by a regional fault (La Salina Thrust). East of the fault, a deformed belt is characterized by tight, horizontal and upright concentric and box folds with pervasive axial-planar cleavage within a Lower Cretaceous, mostly sandy sequence. West the fault, the structural style is characterized by thrust sheets with prominent footwall deformation and isoclinal folding in the hanging wall. At least four stacked thrust sheets that repeat Upper Cretaceous sequences define a regional-scale duplex (El Trigo-Bituima anticlinal stack duplex). Immediately west of the anticlinal duplex, a regional syncline (Guaduas) folds a ∼1.5 km-thick, middle Eocene to Oligocene molasse deposit. The western flank of the syncline is thrusted (Cambras Thrust) on to a ∼2 km-thick Miocene molasse deposit repeated by the frontal thrust of the Eastern Cordillera (Honda Thrust). Line-balancing of a 30 km-long cross-section that includes the Honda Thrust results in a shortening value of ∼60 % (∼45 km) not considering layer-parallel shortening. Reconstruction of the original geometry suggests the presence of two rift-fault systems: one to the east, where the thickness of Cretaceous sequence changes from ∼4 to 3 km, and another one ∼50 km to the west, where the ∼3 km-thick Cretaceous sequence thins to nothing. The former is reactivated as the La Salina Thrust and likely contains pre-Cretaceous basement rocks in its hanging wall, and the latter is not reactivated, as previous studies had proposed. All of this is consistent with a main pulse of growth of the Eastern Cordillera and major surface elevation gain starting in middle Eocene times.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"171 ","pages":"Article 105918"},"PeriodicalIF":1.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760625","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 : 2025-12-08DOI: 10.1016/j.jsames.2025.105917
María Florencia Ahumada , Marcelo Gonzalez , Franco Clavel Alvarado , Héctor P.A. García , Federico Lince Klinger , Francisco Ruiz
The Guayatayoc salt flat basin, located in the northern sector of the Argentine Puna region (Jujuy province), stands out as one of the most promising areas for in depth geophysical research, focused on brine exploration. This region is considered one of the primary areas hosting several economically important lithium brine deposits. These results were obtained using gravimetry, audio-magnetotelluric (AMT), electrical resistivity tomography (ERT), magnetometry, and refraction seismic techniques. The main objective was to characterize the subsurface properties to infer the presence of clastic and/or evaporitic facies potentially carrying brines, as well as to identify marginal aquifers zones or freshwater sources that contribute to recharge and analyze the structural controls of the basin.
Two 2D geological models were developed, revealing a structurally segmented basin into high and low blocks, with three sub-basins delimited by Paleozoic-Cretaceous basement blocks uplifted by faults. A sedimentary unit with densities and electrical resistivity compatible with saturated sands and gravels, possibly carrying brackish water or clay-rich formation containing brines was modeled.
This work represents one of the few published studies that integrate multiple geophysical methodologies for the characterization of a salt flat basin located in the Puna region of Argentina. The use of multiple geophysical techniques promotes best practices in geophysical exploration and responsible resource management. This methodology can be replicated in other saline regions within the Lithium Triangle.
{"title":"Structural and groundwater exploration in the Guayatayoc salt flat basin (Puna Oriental Jujeña, northwest Argentina), using multiple geophysical techniques","authors":"María Florencia Ahumada , Marcelo Gonzalez , Franco Clavel Alvarado , Héctor P.A. García , Federico Lince Klinger , Francisco Ruiz","doi":"10.1016/j.jsames.2025.105917","DOIUrl":"10.1016/j.jsames.2025.105917","url":null,"abstract":"<div><div>The Guayatayoc salt flat basin, located in the northern sector of the Argentine Puna region (Jujuy province), stands out as one of the most promising areas for in depth geophysical research, focused on brine exploration. This region is considered one of the primary areas hosting several economically important lithium brine deposits. These results were obtained using gravimetry, audio-magnetotelluric (AMT), electrical resistivity tomography (ERT), magnetometry, and refraction seismic techniques. The main objective was to characterize the subsurface properties to infer the presence of clastic and/or evaporitic facies potentially carrying brines, as well as to identify marginal aquifers zones or freshwater sources that contribute to recharge and analyze the structural controls of the basin.</div><div>Two 2D geological models were developed, revealing a structurally segmented basin into high and low blocks, with three sub-basins delimited by Paleozoic-Cretaceous basement blocks uplifted by faults. A sedimentary unit with densities and electrical resistivity compatible with saturated sands and gravels, possibly carrying brackish water or clay-rich formation containing brines was modeled.</div><div>This work represents one of the few published studies that integrate multiple geophysical methodologies for the characterization of a salt flat basin located in the Puna region of Argentina. The use of multiple geophysical techniques promotes best practices in geophysical exploration and responsible resource management. This methodology can be replicated in other saline regions within the Lithium Triangle.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"170 ","pages":"Article 105917"},"PeriodicalIF":1.5,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737898","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 : 2025-12-05DOI: 10.1016/j.jsames.2025.105898
Camila Loaiza , Benigno Godoy , Nataly Freire , Osvaldo González-Maurel , Inés Rodríguez Araneda , Petrus le Roux , Juan Figueroa
Magmas in the Central Andes have evolved through fractional crystallization and crustal assimilation, operating at different crustal levels during their ascent through the ∼70 km-thick continental crust. Sairecabur stratovolcano, located within the Altiplano–Puna Volcanic Complex (APVC; 21°–24° S) of the Central Andean subduction zone, is stratigraphically divided into three units: Pre-Caldera Lavas (PRECL - Pleistocene), Post-Caldera I Lavas (POCIL - Upper Pleistocene), and Post-Caldera II Lavas (POCIIL - Holocene). These volcanic products range from 55 (basaltic andesite) to 63 (dacite) wt.% SiO2. In particular, Sairecabur shows a negative correlation between SiO2 wt.% and Eu/Eu∗, with Eu/Eu∗ values < 1, indicating the key role of plagioclase during late-stage magma differentiation. A deep-crustal garnet signature - though not prominent - cannot be excluded, which was overprinted by shallow differentiation and assimilation. Over the past 10 Ma, APVC magmas have been affected by significant crustal contamination, linked to crustal thickening during the Andean orogeny and localized processes. This trend is observed in all units of Sairecabur, where 87Sr/86Sr ratios of erupted products range from 0.707057 to 0.708667. This suggests a substantial crustal assimilation of a parental Andean-type magmas (87Sr/86Sr ratio ∼0.705), which was generated by an early stage of magmatic differentiation at lower crustal levels (MASH zone). Petrographic and geochemical data define three main mid-to-upper crustal evolutionary stages occurring afterwards: (1) an AFC stage in mid-to upper-crustal chambers, with 33–47 % AFC-type incorporation of felsic upper crustal material; (2) an intermediate stage of closed-system fractional crystallization involving plagioclase, pyroxene, amphibole, and biotite; and (3) a late-stage episode of magma mixing with shallow crustal melts, evidenced by glomeroporphyritic gabbroic aggregates and by trace-element trends and scatter accompanying advanced differentiation.
{"title":"Petrogenesis of a highly contaminated magmas by ascent through a thick continental crust: The case of Sairecabur volcano, Central Andes","authors":"Camila Loaiza , Benigno Godoy , Nataly Freire , Osvaldo González-Maurel , Inés Rodríguez Araneda , Petrus le Roux , Juan Figueroa","doi":"10.1016/j.jsames.2025.105898","DOIUrl":"10.1016/j.jsames.2025.105898","url":null,"abstract":"<div><div>Magmas in the Central Andes have evolved through fractional crystallization and crustal assimilation, operating at different crustal levels during their ascent through the ∼70 km-thick continental crust. Sairecabur stratovolcano, located within the Altiplano–Puna Volcanic Complex (APVC; 21°–24° S) of the Central Andean subduction zone, is stratigraphically divided into three units: Pre-Caldera Lavas (PRECL - Pleistocene), Post-Caldera I Lavas (POCIL - Upper Pleistocene), and Post-Caldera II Lavas (POCIIL - Holocene). These volcanic products range from 55 (basaltic andesite) to 63 (dacite) wt.% SiO<sub>2</sub>. In particular, Sairecabur shows a negative correlation between SiO<sub>2</sub> wt.% and Eu/Eu∗, with Eu/Eu∗ values < 1, indicating the key role of plagioclase during late-stage magma differentiation. A deep-crustal garnet signature - though not prominent - cannot be excluded, which was overprinted by shallow differentiation and assimilation. Over the past 10 Ma, APVC magmas have been affected by significant crustal contamination, linked to crustal thickening during the Andean orogeny and localized processes. This trend is observed in all units of Sairecabur, where <sup>87</sup>Sr/<sup>86</sup>Sr ratios of erupted products range from 0.707057 to 0.708667. This suggests a substantial crustal assimilation of a parental Andean-type magmas (<sup>87</sup>Sr/<sup>86</sup>Sr ratio ∼0.705), which was generated by an early stage of magmatic differentiation at lower crustal levels (MASH zone). Petrographic and geochemical data define three main mid-to-upper crustal evolutionary stages occurring afterwards: (1) an AFC stage in mid-to upper-crustal chambers, with 33–47 % AFC-type incorporation of felsic upper crustal material; (2) an intermediate stage of closed-system fractional crystallization involving plagioclase, pyroxene, amphibole, and biotite; and (3) a late-stage episode of magma mixing with shallow crustal melts, evidenced by glomeroporphyritic gabbroic aggregates and by trace-element trends and scatter accompanying advanced differentiation.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"170 ","pages":"Article 105898"},"PeriodicalIF":1.5,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737896","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 : 2025-12-05DOI: 10.1016/j.jsames.2025.105911
Micaela García , Joaquín Bucher , Rodrigo Feo , Manuel López , Florencia Milanese , Magdalena Tettamanti , Leandro D’Elia , Andrés Bilmes , Juan R. Franzese
The Patagonian Broken Foreland (PBF) comprises isolated, fault-bounded Neogene basins displaying intricate internal deformation patterns. Although previous studies emphasized reverse faulting along basin boundaries, the role of strike-slip deformation and intra-basin strain partitioning remains poorly constrained. Through a multidisciplinary approach combining structural analysis, paleomagnetic data, and Digital Outcrop Model analyses, this work investigates three key PBF basins: Paso del Sapo, Piedra del Águila, and Collón Cura. Results document widespread distributed deformation characterized by clockwise vertical-axis block rotation controlled by internal oblique-slip faults and inherited basement structures. In the Paso del Sapo Basin, rotations are most pronounced within internal blocks, transitioning to tilting toward basin boundaries. The Piedra del Águila Basin records localized block rotation linked to angular relationships between strata and abrupt dip changes related to tilting of internal structures. The Collón Cura Basin records sustained rotation in fault-bounded blocks that persisted until ∼10 Ma. The magnitude of block rotation decreases upward in stratigraphy, indicating a progressive deformation history. Kinematic data reveal a transpressional regime involving coeval strike-slip and reverse faulting, resulting in spatial variations in strain partitioning across the basins. These findings underscore the value of multidisciplinary approaches to fully characterize retroarc foreland deformation, including the often-overlooked strike-slip components.
巴塔哥尼亚破碎前陆（PBF）由孤立的断界新近纪盆地组成，具有复杂的内部变形模式。尽管以往的研究强调沿盆地边界的逆断裂作用，但走滑变形和盆地内应变分配的作用仍然缺乏明确的认识。通过多学科方法，结合构造分析、古地磁数据和数字露头模型分析，研究了三个关键的PBF盆地：Paso del Sapo、Piedra del Águila和Collón Cura。结果表明，受内部斜滑断层和继承基底构造控制，以顺时针方向块体旋转为特征的大面积分布变形。在Paso del Sapo盆地，旋转在内部块体中最为明显，过渡到向盆地边界倾斜。Piedra del Águila盆地记录了与地层之间的角度关系有关的局部块体旋转和与内部构造倾斜有关的突然倾角变化。Collón库拉盆地记录了断界块体的持续旋转，持续到~ 10 Ma。块体旋转的幅度在地层上逐渐减小，显示出一个渐进的变形历史。运动学数据揭示了一个涉及同期走滑和逆断裂的逆挤压机制，导致了盆地应变分配的空间变化。这些发现强调了多学科方法全面表征弧后前陆变形的价值，包括经常被忽视的走滑分量。
{"title":"Transpressional deformation and block rotation in the Patagonian Broken Foreland: Multidisciplinary approach and future perspectives","authors":"Micaela García , Joaquín Bucher , Rodrigo Feo , Manuel López , Florencia Milanese , Magdalena Tettamanti , Leandro D’Elia , Andrés Bilmes , Juan R. Franzese","doi":"10.1016/j.jsames.2025.105911","DOIUrl":"10.1016/j.jsames.2025.105911","url":null,"abstract":"<div><div>The Patagonian Broken Foreland (PBF) comprises isolated, fault-bounded Neogene basins displaying intricate internal deformation patterns. Although previous studies emphasized reverse faulting along basin boundaries, the role of strike-slip deformation and intra-basin strain partitioning remains poorly constrained. Through a multidisciplinary approach combining structural analysis, paleomagnetic data, and Digital Outcrop Model analyses, this work investigates three key PBF basins: Paso del Sapo, Piedra del Águila, and Collón Cura. Results document widespread distributed deformation characterized by clockwise vertical-axis block rotation controlled by internal oblique-slip faults and inherited basement structures. In the Paso del Sapo Basin, rotations are most pronounced within internal blocks, transitioning to tilting toward basin boundaries. The Piedra del Águila Basin records localized block rotation linked to angular relationships between strata and abrupt dip changes related to tilting of internal structures. The Collón Cura Basin records sustained rotation in fault-bounded blocks that persisted until ∼10 Ma. The magnitude of block rotation decreases upward in stratigraphy, indicating a progressive deformation history. Kinematic data reveal a transpressional regime involving coeval strike-slip and reverse faulting, resulting in spatial variations in strain partitioning across the basins. These findings underscore the value of multidisciplinary approaches to fully characterize retroarc foreland deformation, including the often-overlooked strike-slip components.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"170 ","pages":"Article 105911"},"PeriodicalIF":1.5,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737897","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 : 2025-12-03DOI: 10.1016/j.jsames.2025.105901
Ernesto O. Cristallini , Agostina D'Ascenzo , Renata N. Tomezzoli , Melina E. Gugliotta , Nicolás Braun
Aquí se presenta una interpretación de las principales estructuras geológicas cenozoicas aflorantes en la cuenca de Fiambalá, también conocida como Bolsón de Fiambalá provincia de Catamarca, Argentina. La compresión andina deformó las secuencias sedimentarias neógenas formando una serie de corrimientos dispuestos en sentido ∼ N-S con vergencia hacia el este. A partir de la información relevada en el campo, integrada con estudios geológicos previos e imágenes satelitales, se elaboró una sección estructural balanceada con el fin de caracterizar la deformación del área y se realizó una reconstrucción palinspástica a partir del cual se calculó un acortamiento total de 6.13 km, equivalente al 18 % para la región.
ABSTRACT
We present an interpretation of the main Cenozoic geological structures outcropping in the Fiambalá Basin, also known as Bolsón de Fiambalá, Catamarca Province, Argentina. Andean compression deformed the Neogene sedimentary sequences, forming a series of thrusts arranged in a north-south direction with eastward convergence. Based on own field collected data, combined with previous geological studies and satellite images, a balanced structural section was constructed to characterize the deformation of the area. A palinspastic reconstruction was performed, from which a total shortening of 6.13 km was calculated, equivalent to an 18%, for the studied region.
本文介绍了阿根廷卡塔马卡省Fiambala盆地主要的新世地质构造，也被称为Bolson de Fiambala。安第斯山脉的压缩变形了新近形成的沉积序列，形成了一系列在~ N-S方向上向东倾斜的洋流。信息relevada起地质综合领域,与以前的卫星图像,制定了一个结构平衡的部分,旨在确定区域和变形进行了重建palinspástica从中计算总缩减为6.13平方公里区域,相当于18 %。本文对阿根廷卡塔马卡省菲安巴拉盆地主要的世生代地质结构的解释，也被称为Bolson de Fiambala。这是一个巨大的隆起，形成了一个巨大的隆起，形成了一个巨大的隆起，形成了一个巨大的隆起。根据现场收集的数据，结合以前的地质研究和卫星图像，建造了一个平衡的结构部分，以表征该地区的变形。进行了palinspastic重建，计算出研究区域的总缩短6.13公里，相当于18%。
{"title":"Structural Andean evolution of the western border of the central Fiambalá basin, Catamarca province, Argentina","authors":"Ernesto O. Cristallini , Agostina D'Ascenzo , Renata N. Tomezzoli , Melina E. Gugliotta , Nicolás Braun","doi":"10.1016/j.jsames.2025.105901","DOIUrl":"10.1016/j.jsames.2025.105901","url":null,"abstract":"<div><div>Aquí se presenta una interpretación de las principales estructuras geológicas cenozoicas aflorantes en la cuenca de Fiambalá, también conocida como Bolsón de Fiambalá provincia de Catamarca, Argentina. La compresión andina deformó las secuencias sedimentarias neógenas formando una serie de corrimientos dispuestos en sentido ∼ N-S con vergencia hacia el este. A partir de la información relevada en el campo, integrada con estudios geológicos previos e imágenes satelitales, se elaboró una sección estructural balanceada con el fin de caracterizar la deformación del área y se realizó una reconstrucción palinspástica a partir del cual se calculó un acortamiento total de 6.13 km, equivalente al 18 % para la región.</div></div><div><h3>ABSTRACT</h3><div>We present an interpretation of the main Cenozoic geological structures outcropping in the Fiambalá Basin, also known as Bolsón de Fiambalá, Catamarca Province, Argentina. Andean compression deformed the Neogene sedimentary sequences, forming a series of thrusts arranged in a north-south direction with eastward convergence. Based on own field collected data, combined with previous geological studies and satellite images, a balanced structural section was constructed to characterize the deformation of the area. A palinspastic reconstruction was performed, from which a total shortening of 6.13 km was calculated, equivalent to an 18%, for the studied region.</div></div>","PeriodicalId":50047,"journal":{"name":"Journal of South American Earth Sciences","volume":"170 ","pages":"Article 105901"},"PeriodicalIF":1.5,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145694509","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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