Latin American Journal of Sedimentology and Basin Analysis
The Latin American Journal of Sedimentology and Basin Analysis (LAJSBA) is the official publication of the Argentinean Association of Sedimentology (AAS). Formerly AAS Revista, it has been published uninterruptedly since 1994. The numbers of the AAS Revista published between 1994 and 2004 are available on the SciELO-Argentina website. The fundamental aim of the LAJSBA is to publish original research papers, reviews and technical notes dealing with all aspects of the sedimentology, sedimentary rocks, sediment dynamics and related disciplines such as basin analysis, stratigraphy, paleoecology, paleogeography, etc. that provide a timely contribution to the advance in this field of the Earth Sciences. LAJSBA is published twice a year, in July and December. Official languages of the journal are Spanish, Portuguese and English. However, taking into account the future expansion of the LAJSBA we will consider favorably those papers submitted in English. Open Access LAJSBA is an open access journal, which means that all of its content is available free of charge to the readers and institutions. The full texts of the scientific articles published in this journal are available in the Archives section. LAJSBA provides open and immediate access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge. Indexing Information of LAJSBA LAJSBA is cited in SCOPUS, GeoRef, Latindex, REDIB and SciELO. It has been incorporated to Núcleo Básico de Revistas Científicas Argentinas. LAJSBA is indexed by SCimago Journal Ranking since 2013 and ICI Journals Master List since 2019.
Golfo San Jorge Basin: thematic synthesis, recent developments and a look forward
This contribution provides an overview of the content of this Special Number of the Latin American Journal of Sedimentology and Basin Analysis, which explores the geological evolution of the Golfo San Jorge Basin and the challenges it faces within the current context of hydrocarbon resource depletion and global warming. The Special Number comprises eight peer-reviewed articles synthesizing current knowledge across multiple disciplines. The topics covered include: (i) magmatic evolution (Navarrete); (ii) structural geology (Allard et al.); (iii) stratigraphy and provenance (Paredes et al.; Olazábal et al.; Foix et al.); (iv) paleosol development (Lizzoli and Raigemborn); and (v) Cretaceous biostratigraphy (Pérez Loinaze; De Sosa Tomas and Vallati). These contributions present recent advances in their respective fields and highlight critical unresolved questions that must be addressed to further our understanding of the geological evolution of the Golfo San Jorge Basin.
Copyright (c) 2025 José M. Paredes https://creativecommons.org/licenses/by-nc/4.0
PREDICTIONS OF THE IMPACTS OF THE SEA-LEVEL RISE IN ARGENTINA
Sea level is rising and it is expected to continue rising as the atmosphere is warming inducing glacier melting. Based on this melting a minimum of 0.4 m of sea level rise (SLR) is expected for the year 2100. Coastal erosion is the more evident consequence of this SLR. At estuarine areas these effects are more difficult to discern. In some areas climate is warming and rains are increasing, and are thought to continue doing so in Buenos Aires; but they are decreasing in Patagonia. Therefore, estuarine areas, freshwater and salt marshes have different responses along the Argentine coast. More important are the effects in urban areas where planners and administrators have systematically disregarded the subject. In low-lying areas as Samborombón Bay the SLR will cause a surface retreat of the salt-fresh water interactions. Therefore, General Lavalle city will be more dependant of the surface freshwater runoff of the Channel 2. Flash floods today can affect the city of San Clemente del Tuyú but the performance of the discharge pipelines depends on the meteorological effects on the tides. Flash floods have also affected coastal cities of the desertic Patagonia: Puerto Madryn and Comodoro Rivadavia have suffered unprecedented floods during recent years. Two models applied to coast evolution in response to SLR. Bruun`s model predicts shore erosion and deposition below the depth where there is no wave action (closure depth). However, in low-lying areas where there is enough sediment availability the onshore migration of bedforms (beaches, cheniers) can occur. Changes in estuarine areas are more difficult to predict. Tidal prisms can increase significantly in microtidal coasts due to SLR, but in macrotidal coasts these increments were not significant. Another effect of the SLR occurs at the hydrogeological interphase between fresh and salt waters. The simulation of these interactions should be carefully estimated considering the groundwater discharge and the climate change effects on the Precipitation.
Copyright (c) 2025 Federico Ignacio Isla https://creativecommons.org/licenses/by-nc/4.0
Cenozoic stratigraphy of the Golfo San Jorge Basin (Argentina): an integrated record of tectonic, climatic, and eustatic controls on basin evolution
The Golfo San Jorge Basin (GSJB) preserves the thickest Cenozoic stratigraphic record in extra-Andean Patagonia (Argentina), reaching approximately 1500 meters. This record was subdivided into three major second-order transgressive regressive (TST-RST) sedimentary sequences: (1) The early Paleogene T-R cycle (~ 600 m thick; early Paleocene–late Eocene), comprising the Salamanca Formation (marine), Río Chico Group (fluvial), and part of Sarmiento Formation (pyroclastic loess). This sequence reflects a marine-to-continental transition, with an early marine stage marked by tidally-influenced, shallow-marine and inner-shelf sedimentation, followed by fluvial systems and long-lived accumulation and reworking of fine ash in a low-gradient continental setting. (2) The late Paleogene-early Neogene T-R cycle (~ 200 m thick, late Eocene-early Miocene), composed of the El Huemul Formation (marine) and the upper part of Sarmiento Formation (pyroclastic deposits). (3) The Neogene T-R cycle (~ 700 m thick; early–middle Miocene), includes the Chenque Formation (marine) and the Santa Cruz or Escalante Formation (fluvial-eolian). The three marine second order TSTs share similar temporal duration (<5 million years) and sedimentation patterns are strongly influenced by continental slope inheritance. However, the continental second-order RSTs differ significantly: (i) the early Paleogene RST lasted ~ 22 million years, compared with the ~ 10 million years of the late Paleogene-early Neogene cycle and the ~ 5 million years of the Neogene; (ii) the Paleogene records extensive global climatic fluctuations, whereas the Neogene is characterized by a single wet to dry cycle; (iii) pyroclastic deposits dominate the early Paleogene and late Paleogene-early Neogene sequences, but they are nearly absent in the Neogene; (iv) the first two second order continental cycles preserves an exceptional assemblage of continental mammal faunas, serving as a biostratigraphic reference for South America. Although the GSJB’s macrostratigraphy correlates strongly with regional sea-level fluctuations, additional controlling factors have been proposed, including extensional tectonic reactivations, Andean orogenic uplift, intrusion-related tectonic loading, sustained pyroclastic input, climatic variability, and dynamic topography.
Copyright (c) 2025 Nicolás Foix, José M. Paredes, Francisco Emanuel Oporto Romero, José Oscar Allard https://creativecommons.org/licenses/by-nc/4.0
Predictive analysis of total organic carbon (TOC) in shale targets: example from the Lower Cretaceous of the Austral Basin (Patagonia, Argentina) using machine learning on outcrop data
The Río Mayer Formation (Lower Cretaceous) of the Austral Basin, Patagonia, is a key source rock for unconventional reservoirs. This study explores the potential of machine learning (ML) for predicting Total Organic Carbon (TOC) content using outcrop data, a novel approach compared to traditional subsurface data applications. Employing dimensional reduction techniques (PCA, T-SNE, UMAP), the analysis revealed clear clustering of high TOC values in feature space, supporting the feasibility of predictive modeling. Three ML models —Logistic Regression, Support Vector Classifier (SVC), and KNearest Neighbors (KNN)— were tested using a feature set derived from ANOVA F-Score rankings. Dimensionality reduction improved model performance, with SVC achieving the most robust results. Despite limited labeled samples, predictions across models were consistent, identifying a promising region for high TOC. The study highlights the importance of integrating geological variables and XRD data in TOC modeling and emphasizes the need for expanded datasets and additional sedimentary sections to enhance regional interpretations.
Copyright (c) 2025 Sebastián M. Richiano, Federico Ares https://creativecommons.org/licenses/by-nc/4.0
Structural framework and evolution of the Golfo San Jorge Basin: a synthesis
The Golfo San Jorge Basin evolved through a complex multiphase structural history from the Middle Jurassic to the Neogene. Its stratigraphic record captures key tectonic events in central extra-Andean Patagonia during Gondwana fragmentation and the Andes construction, allowing us to refine and calibrate multiscale structural processes associated with extension and positive tectonic inversion. The structural architecture reflects the interplay of upper-crustal remote stress, active basement structures, coaxial and non-coaxial extensional reactivations, short-wavelength tectonic inversion, thermal subsidence, and mantle processes. A comprehensive understanding of these interactions is crucial for improving regional basin models with broader implications for tectonic and petroleum system studies.
Copyright (c) 2025 José O. Allard, Nicolás Foix, José M. Paredes, Raúl E. Giacosa, Sebastián A. Bueti, Francisco E. Oporto Romero, Agustín R. Rodríguez https://creativecommons.org/licenses/by-nc/4.0
The Chubut Group (Cretaceous, Golfo San Jorge Basin): A synthesis of its sedimentary petrography
This study presents a synthesis of petrographic analyses of the cretaceous Pozo D-129, Matasiete, Castillo, and Bajo Barreal formations in the Golfo San Jorge Basin, highlighting the influence of volcanic activity and sediment supply on the evolution of the Chubut Group. Data from outcrops in the San Bernardo Fold Belt and from the subsurface indicate that sandstone compositional variability was controlled by shifts in sediment source areas, linked to regional tectonic processes and active volcanism. Sandstones exhibit feldspatho-lithic and litho-feldspathic qFL, fQL, IQF to qLF composition detrital modes, with spatial and temporal variations in volcanic, pyroclastic lithic, feldspar and quartz components. The sediment sources for the outcrops in the San Bernardo Fold Belt include the Paleozoic igneous-metamorphic basement, Middle-Upper Jurassic volcanic and volcaniclastic rocks (Lonco Trapial Group), and acidic and pyroclastic sequences assigned to the Marifil Group. In contrast, the South Flank records a broader range of petrofacies, reflecting a combination of distal and local sources. In addition to the provenance of the Andes Cordillera, this sector received sediment contributions from Jurassic rocks exposed in the Deseado Region and older crystalline basement units. Andean volcanism dominates across all units, contributing direct volcanic ash fallout and reworked pyroclastic material.
Copyright (c) 2025 Sabrina Olazábal, Maisa A. Tunik , José M. Paredes, José O. Allard , Nicolás Foix https://creativecommons.org/licenses/by-nc/4.0
Expanding knowledge of hothouse conditions through the study of paleosols in the southern Golfo San Jorge Basin
Hothouse periods, such as the mid-Cretaceous and early Eocene, were times of global warming with high levels of greenhouse gases, elevated temperatures, and ice-free poles that provide a case study for understanding past climate dynamics. This study examines the paleo-Ultisols from the Bajo Barreal Formation (BBF; Cenomanian) and the Las Flores Formation (LFF; early Eocene) in central Patagonia (southern region of the Golfo San Jorge Basin). Due to their prolonged soil formation, these well-developed paleosols serve as valuable climate indicators. These paleosols were analyzed using a multi-proxy approach to understand their significance during those two periods in the Southern Hemisphere. The BBF Ultisols (mid-Cretaceous, ~51° paleo-S) display kaolinite-rich Bt horizons, formed under intense chemical weathering conditions and leaching processes, linked to a temperate and humid climate. On the other side, the LFF Ultisols (early Eocene, ~52° paleo-S) with kaolinite-dominated Bt and/or Btv horizons reflect their formation under higher chemical weathering and leaching processes, under a temperate-tropical and humid climate. For the times of formation of both BBF and LFF paleo-Ultisols, both localities were within the Warm Temperate climate zone. In contrast, this zone currently extends to approximately 40° N and S latitude. Present-day Patagonia is in the Arid climate zone, with much drier and cooler climate that contrasts with the warmer, wetter conditions of the Cenomanian and early Eocene localities analyzed. These findings highlight significant latitudinal displacement of climate zones during hothouse periods, emphasizing their importance in understanding past climate dynamics and providing insights into future climate change scenarios.
Copyright (c) 2025 Sabrina Lizzoli, María Sol Raigemborn https://creativecommons.org/licenses/by-nc/4.0
Copyright (c) 2024 José I. Cuitiño https://creativecommons.org/licenses/by-nc/4.0
A synthesis of palynological data recovered from “Neocomian” deposits of the Golfo San Jorge Basin
This contribution provides a synthesis of the palynological studies carried out on “Neocomian” units of the Golfo San Jorge Basin. Additionally, a revision of the palynological zones established for these units in previous works is presented, incorporating insights from new contributions and recent taxonomic novelties. Based on the palynological record, the age of the Las Heras Group is considered as not younger than Hauterivian at the northern and southern flanks of the Golfo San Jorge Basin. In contrast, the age of this group extends to the Aptian in the western area. Nevertheless, more detailed palynological studies and an evaluation of the current status of the stratigraphic units recognized in the analyzed wells are needed to confirm and expand these results.
Copyright (c) 2025 Valeria Perez Loinaze https://creativecommons.org/licenses/by-nc/4.0
Stratigraphy of the Chubut Group (Cretaceous, Golfo San Jorge Basin, Argentina): impacts of allogenic controls on the alluvial macro-architecture
The Chubut Group (Cretaceous, Golfo San Jorge Basin) is a continental succession up to 6,000 meters thick, preserved in an endorheic basin. Its basal depositional system includes the fluvial Matasiete Formation and the lacustrine Pozo D-129 Formation, the main source rock for the hydrocarbons of the basin. The Matasiete Formation (Aptian) represents a high-accommodation, exotic fluvial system with headwaters in the present-day Cañadón Asfalto Basin (CAB), referred to as the Los Adobes Formation. Sediment was transported southward to a saline-alkaline lake (Pozo D-129 Formation) through N-S sedimentary corridors in an extensional setting. The overlying depositional system is integrated by the Castillo and Mina del Carmen formations (Albian-Cenomanian?), and it consists of reworked volcaniclastic particles in drainage catchments within a W-E elongated extensional basin, disconnected from the CAB. The subsequent depositional system includes the Bajo Barreal Formation (Cenomanian- Coniacian?), containing the main hydrocarbon reservoirs. It shows varied stacking density in hundreds of meters thick cycles, linked to climatic cycles. Low net-to-gross fluvial stratigraphy featuring small-scale channel belts and paleosols indicates a temperate, subhumid/humid climate with seasonal rainfall. High net-to-gross fluvial stratigraphy records larger-scale channel belts interbedded with paleosols developed in a warmer, humid climate with perennial rainfall. The uppermost depositional system includes the paleosol-rich Laguna Palacios Formation at basin margins, with maximum thicknesses along syncline axes, and the red-colored, anastomosing fluvial systems of the Maastrichtian Colhué Huapi Formation that fill incised valleys. Both units are equivalent to the upper strata of Meseta Espinosa and El Trébol formations in the subsurface, showing degradational features marking the onset of surface uplift in the San Bernardo Fold Belt.
Copyright (c) 2025 José Matildo Paredes, Nicolás Foix, José O. Allard, Sabrina Lizzoli, Sabrina X. Olazábal, Maisa A. Tunik https://creativecommons.org/licenses/by-nc/4.0
An overview of the Late Triassic–Pleistocene magmatism in the Golfo San Jorge Basin
The Patagonian Late Triassic–Pleistocene magmatic history encompasses multiple intraplate and subduction–related events associated with diverse geodynamic settings. Key episodes include the Late Triassic and Late Cretaceous–Paleocene flat slabs, the Cenozoic subduction of two mid-ocean ridges, slab break-off and tearing events during the Jurassic, Cretaceous–Paleocene, and Late Miocene–Pleistocene, as well as the influence of the mantle transition zone from the latest Eocene to the Middle Miocene. These processes collectively triggered significant magmatic episodes across the region. This overview highlights the main features of these magmatic events, their associated geodynamic contexts, and the proposed petrogenetic models, focusing on the central Patagonian region, including the Golfo San Jorge Basin and its surrounding areas.
Copyright (c) 2025 César Rodrigo Navarrete Granzotto https://creativecommons.org/licenses/by-nc/4.0
Insight into cretaceous floras: a synthesis from plant microfossils of the Chubut Group in the Golfo San Jorge Basin
This study provides a comprehensive review of key advances in micropaleontological research of the Chubut Group in the Golfo San Jorge Basin during the twenty-first century, with a particular emphasis on the plant microfossil record of two critical stratigraphic units: the Pozo D-129 Formation and the Lago Colhué Huapi Formation. The Pozo D-129 Formation, which outcrops at the Sierra Silva anticline, contains gyrogonites and utricles belonging to the Characeae and Clavatoraceae families, as well as a palynoflora assemblage that includes primitive angiosperm pollen grains. The analyzed microfossil assemblages suggest a late early Aptian age for these deposits and provide valuable insights into the freshwater paleoenvironment, which developed under semiarid conditions. In contrast, the microfossil record from the upper levels of the Lago Colhué Huapi Formation, recovered from outcrops at the headwaters of the Río Chico, did not yield charophytes but revealed rich palynological assemblages, including several megaspores from the orders Salviniales, Isoetales, and Selaginellales, along with additional palaeobotanical remains such as charcoal. These findings significantly contribute to interpreting a late Maastrichtian age and facilitate the reconstruction of the vegetation that thrived in freshwater environments under warm and humid climatic conditions.
Copyright (c) 2025 Andrea De Sosa Tomas, Patricia Vallati https://creativecommons.org/licenses/by-nc/4.0
Deciphering the origin of linear landforms using different sedimentological tools in the Fiambalá Valley (Catamarca)
The current study is centered on the morphological, textural, and compositional characterization of several linear landforms identified in the west and center of the Fiambalá Valley, in the western region of the Catamarca province (Argentina), along the terraces of the Apocango River. These landforms are slightly asymmetric to symmetric, with rounded crests, a few meters high (between 0.3 and 3.5 m) and several meters wide (from 8 to 14.5 m). They have straight to slightly sinuous ridges with NE-E to SW-W direction and are arranged as isolated bodies. The superficial cover has a bimodal frequency distribution with a primary mode in medium to coarse pebble (-4.5 to -3.5 ?) and a secondary mode in fine sand (2.5 ?). Gravel clasts are sub-rounded, with moderate sphericity, and predominantly compact-elongated shape. The analysis of high-resolution photographs of the superficial cover showed they present an open to moderate packing (44.49 - 58.60% of clasts). In a cross-sectional profile, it was observed that internally they consist of fine to medium sand (x: 2.66 - 1.31 ?). Gravel composition is made primarily by clasts of green sedimentary lithics (22.92 - 32.72%), followed by acidic volcanic lithics (15 - 21.49%), purple sedimentary lithics (13.72 - 17.04%), and basic (10.60 - 17.78%) and intermediate (9.74 - 12.93%) volcanic lithics, thus classified as lithic gravels. The sandy fraction is composed of lithics (35.71 - 47.51%), followed by quartz (23.59 - 37.92%), and feldspars (19.80 - 32.76%); consequently, classified as feldspathic litharenites. Regarding the lithic fragments, volcanic types predominate (27.41 - 37.70%), being those of acidic composition with felsitic and microgranular paste (20.06 - 31.15%) the most represented. The thicker superficial cover with open to moderate packing is interpreted as poorly evolved desert pavement. Deposit composition suggests that the main contribution of the gravelly and sandy material comes from the west (Sistema de Famatina), congruent with the source area of the Apocango alluvial system and the preferential directions of wind that transports material from the SW-WSW towards NNE-NE. The rounded crest, straight to slightly sinuous ridges, and their parallel orientation to the main drift potential direction (RDD) agree with the characteristics of moderately to highly deflated linear dunes. Regarding their origin, initially, the area was dominated by eolian sedimentation of linear dunes associated with the migration of wind ripples. In a second stage deflation prevailed, preserving only fine sediments in sheltered areas, probably related to the margins of small secondary channels or gullies. In this stage, active deflation altered the original linear dune morphology and gave rise to poorly evolved desert pavements. This process stabilized linear dunes, forming a protective layer and ensuring immobility.
Copyright (c) 2024 Delfina Fernandez Molina, Patricia L. Ciccioli, Leopoldo D. Serpa, Paloma Amado Silvero https://creativecommons.org/licenses/by-nc/4.0
MiSMoS (MicroScale Morphology System): an inexpensive new method to survey 3D surface micromorphology
Microscale morphology in coastal environments is complex to study due to both the large spatial and temporal variability. No direct instrumentation is available to map the micromorphology in detail. The aim of this article is to describe the application of the newly developed MiSMoS (MicroScale Morphology System) methodology for mapping surface and small-scale morphologic features such as ripples, rills, and small courses, as well as to demonstrate its advantages and limitations. A set of measurements on a perched beach that offers varied microforms was carried out as a case study example. The MiSMoS consists of a table of 1.6 m x 1.6 m square aluminum structure with six L-shaped rails on top to mobilize a sensor-carrying structure, which is supported on 4 legs (0.60 m high). The sensor-carrying structure is built with two cameras and a Laser Distance Meter (LDM), with cameras at a fixed angle of 20°. In the operating procedure for high-resolution mapping, the sensor-carrying structure is manually moved sequentially capturing images that cover a surface of 0.60 x 0.60 m, with 75% overlap. High-resolution 3D models were generated from the images using Structure-from-Motion, Multi-View-Stereo (SfM-MVS) technique. MiSMoS has numerous advantages over commercial instrumentation: 1) it can map topography at a high resolution, 2) it is easy to build and deploy, 3) it is inexpensive, and 4) in one operation, a high-resolution map of an area of 2.25 m2 can be obtained in about 15-20 min, whereas other systems usually only provide profiles.
Copyright (c) 2025 Yajaira Cristina Alquinga Salazar, Sibila A. Genchi, Lucas Nuciari, Vanesa L. Perillo, M. Cintia Piccolo, Gerardo M. E. Perillo https://creativecommons.org/licenses/by-nc/4.0
Early Miocene detrital zircon age from fluvial deposits of La Marcelina Formation in the Deseado Massif, Southern Patagonia, Argentina
The La Marcelina Formation (LMF) in the southern Deseado Massif area (c. 47° 55' S) represents a 23 m thick sedimentary succession deposited within a low-energy fluvial paleoenvironment. The age of this unit, formerly considered as Eocene due to its palynological assemblage, is adjusted by zircon U-Pb Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) from a sandstone bed at the middle part of the unit. The results reveal a maximum depositional age of ~20 Ma (Early Miocene, Burdigalian). The detrital zircon provenance analysis indicates zircon grains originated mostly in the Jurassic, with limited contributions from the Cretaceous, Permian, and Paleocene. The new age for LMF allows correlating these beds to the upper section of the continental Río Leona Formation in the southern Austral-Magallanes Basin.
Copyright (c) 2024 Inés Aramendía, Sol Noetinger, Roberto Pujana, David Barbeu, Juan García-Massini, Sebastián Mirabelli https://creativecommons.org/licenses/by-nc/4.0
Late Quaternary palaeochannels in the distal area of the Salado-Juramento fluvial megafan, South America
The Gran Chaco fluvial systems, South America, constitute a significant type of fluvial record for the modern Andean foreland basin. The Salado-Juramento fluvial megafan (SJFM), one of the largest systems of South America, shows distinctive morphologic and sedimentologic characteristics. The SJFM, developed after the southward Salado-Juramento river displacement, shows numerous paleochannels with an eastward distributive pattern from its apex in the Sierras Subandinas. In this work, we analyze the palaeohydrological attributes and the sedimentology of two paleochannel sections located in distal areas of the SJFM, with the aim to collect stratigraphic and sedimentologic data to infer the dynamics of infill of those paleochannels. From each succession, sediment samples for sedimentologic (mineralogy and grain size) and chronologic analyses were taken. The paleochannels with-to-thickness ratio (W/T) show values between 9.4 and 16.1 (mean 12.75) for the distal area of the SJFM, corresponding to ribbon channels. The paleochannel infill is composed of very fine to fine sand, with a sand and clay composition related to the Salado River. These deposits are covered by layers of eolian clayed silt deposits. The geomorphology, paleohydrologic attributes, sedimentology, and numerical datings suggest a distributive paleodrainage with channels active during the MIS 3 (62-28 Ka BP). A fluvial aggradational phase is interpreted for the MIS 3, mainly represented by sinuous channels infill suggesting numerous divergent rivers in the distal SJFM. By the MIS 2, the activity of the fluvial system diminishes being replaced by clayed silt eolian sedimentation.
Copyright (c) 2024 María Belén Thalmeier , Leticia Rodríguez https://creativecommons.org/licenses/by-nc/4.0
Hydrogeomorphological changes and the erosion-deposition impact in the San Francisco River Basin, northwest Argentina: a multidecadal analysis
Modifications of wetland and forest areas are studied, in particular, to establish to what extent they are sensitive to natural changes (e.g., increased precipitation and/or temperature) in addition to human activities (e.g., advancing agricultural frontier, deforestation, channelizations). The San Francisco River Basin (SFRB; 1,789 km2) is located in the Northwest of Argentina in the Geological Province of Nortwestern Pampean Ranges (Sierras Pampeanas Noroccidentales), between 27°40'S and 28°25'S, and 65°15'W and 65°45'W). In recent decades, agricultural development and management in the middle and lower SFRB generated rural channelizations (the largest of 10 km at the basin outlet between 2005-2015), drainage of wetland forests, deforestation of native dry forest since 1995 and changes in land use. In addition, a 200 mm increase in mean annual rainfall since 1972 and an increase in extreme hydrological events, are registered. These modifications produced changes in local base level, erosive processes of retreat and the development of new river channels from upstream, increasing flow velocities, flow rates, and sediment discharge. The intensified erosive processes resulted in four new river courses in the middle and lower basin, incorporating the SFRB into the Marapa river basin, changing from arheic to endorheic behaviour, and generating the contribution of liquid and solid flows to the system of which it is now a part. The aim of this study is to examine the development of the new hydrographic network within the SFRB between 1990 and 2018 and to calculate the solid and liquid discharges generated by the new network. The hydrographic network formed by the rivers El Abra, Ovanta, San Francisco and Suncho creek, was digitized in the open-source software QGIS 3.18.3 on the basis of the visual interpretation of satellite imagery. The lengths of the rivers were automatically calculated and exported to a spreadsheet to determine the downstream expansion of the river network. Measurements and sampling of water discharge and sediment load were performed monthly in the lower section of the SFRB. The float and cross-section method was used to quantify the flow rates, and the sediment samples were filtered, dried in an oven for 24 h and weighed on a precision balance to obtain the sediment concentration (C in mg/l). The study determined the generation of 102 km of new river channels in a 28 yr period. The hydrographic network had an annual sediment production of 82,138 t/yr and an annual discharge of 21,96 hm3, contributing to the Marapa river basin and generating an acceleration in the silting of the downstream Río Hondo reservoir. This work provides a basis for management and mitigation of erosion and flooding problems in the area.
Copyright (c) 2024 María Antonella Isuani, Sergio Miguel Georgieff, María Soledad Bustos https://creativecommons.org/licenses/by-nc/4.0
Landforms, sediments, and soils: Quaternary study cases of Argentina
Copyright (c) 2023 Alfonsina Tripaldi, Paula Santi Malnis https://creativecommons.org/licenses/by-nc/4.0
Diagenetic evolution of the Permian Tunas Formation, Claromecó Basin, Buenos Aires province, Argentina: its impact on porosity and reservoir characteristics
The foreland Claromecó Basin, located in the south-western sector of Buenos Aires province, Argentina, has a relevant economic and energetic interest due to the presence of coal layers contained in the Permian Tunas Formation, which might be considered effective source rock for gas resource generation. This study aims to reconstruct the diagenetic evolution of the Tunas Formation at the Claromecó Basin (PANG 0001 and PANG 0003 wells) and determine how the diagenesis affected the reservoir quality. To this purpose, core samples of the Tunas Formation were analysed using a combination of micro petrographic analyses (transmitted light, QEMSCAN, cathodoluminescence), fluid inclusions studies, and petrophysical methods (conventional core analysis, CCA). The analysed sedimentary successions are composed of sandstones interbedded with mudrocks, carbonaceous mudrocks, tuffs, and coals. Sandstones are medium- to fine-grained, framework-supported, and moderate-to-well-sorted. Authigenic minerals are calcite and laumontite, with minor proportions of quartz and feldspar overgrowths and clay minerals (illite, muscovite, and chlorite). Porosity is of secondary type, generated by fracturing and dissolution of feldspars and carbonate cement. Porosity determined by optical, QEMSCAN, and CCA analyses ranges from 0.1 to 4 %, with a permeability varying between 10-3 and 10-6 millidarcies. Fluid inclusion studies were performed in sandstone cements and calcite and quartz veins. Primary, pseudo-secondary, and secondary aqueous and organic fluid inclusions were recognized. Organic fluid inclusions show green and light blue fluorescence, which indicates the presence of hydrocarbons. Homogenization temperatures of fluid inclusions obtained from microthermometry studies range from 124 to 200 °C in cements and 110 to 230 °C in veins. These temperatures confirm a metagenesis stage for the Tunas Formation, within the wet to dry gas window. Given the petrophysical characteristics of the analyzed levels, sandstones could be considered unconventional tight gas sandstone reservoirs. Obtained results point out that during early diagenesis, physical compaction and precipitation of carbonate cement are the principal factors that significantly reduce the primary porosity. Furthermore, in the mesogenesis stage, chemical compaction, calcite and zeolite cements precipitation, and quartz overgrowths further contribute to porosity loss. However, secondary porosity was produced during mesogenesis due to the dissolution of unstable grains and calcite cements caused by the action of acid fluids generated during the decomposition and maturity of organic matter. Additionally, secondary porosity was also generated by fracturing due to burial and tectonic stress and by the increased pore pressure during hydrocarbon generation and migration. The reservoir properties of the Claromecó Basin have been controlled mainly by diagenetic and tectonic processes that acted during the burial history of the basin. Clasts and cements composition also influenced diagenesis together with the presence of organic-rich rocks, which could generate hydrocarbons.
Copyright (c) 2024 Maria Belen Febbo, Nora Cesaretti , Silvia Omodeo-Salé , Andrea Moscariello, Antoine de Haller , Natalia Fortunatti, Giselle Choque, Renata Tomezzoli https://creativecommons.org/licenses/by-nc/4.0
Sand pipes as potential indicators of seismicity in the Casa Grande Formation, northwestern Argentina
In fluvial deposits of the Casa Grande Formation (Middle Eocene), a suite of Soft Sediment Deformation Structures (SSDS) have been identified, the genesis of which could be associated with seismic movements (seismites). This formation has been linked to the early stages of evolution of the Andean foreland basin in the transition between the Puna and the Eastern Cordillera. This study focuses on describing and interpreting discordant structures understood as sand pipes and the processes related to their formation. These structures are characterized by an inverted funnel morphology and are distinguished by their metric-scale dimensions. Associated with the sand pipes, disturbed lamination, pillar and plate structures, clastic dikes, and load casts were recognized and described. Considering the characteristics of these structures, liquefaction and fluidization processes are interpreted as the formative mechanisms. Based on the deposit and structures characteristics, presence in restricted stratigraphic intervals, lateral continuity, vertical repetition, proximity to faults, and similarity to structures produced by recent earthquakes, seismic events are proposed as the triggering mechanism for the deformation.
Copyright (c) 2024 Mario Albertengo, Cecilia del Papa, Ayelén Lapiana https://creativecommons.org/licenses/by-nc/4.0
Fire effects on rock weathering in the North Patagonian Andean Range
Fire-induced rock exfoliation is a rapid mechanical weathering process characterized by an uneven heating and thermal expansion stress that causes the detachment of rock peels, flakes or spalls. We examined 18 granitoid erratic blocks on a gradient of fire severity in a burned inselberg near El Bolsón, during March 2023. Among them, 13 blocks showed fire spalling, producing 0.1 to 6 kg/m2 of sediment on rock surfaces with an average of 1.72 kg/m2. The incidence of fire spalling showed a more pronounced occurrence within areas of higher severity above dNBR 800. This study is the first mention of fire-induced weathering in the Patagonian Andes, which underlines the need to investigate the intricate relationship between forest fires and the denudation of vegetated outcrops in the region.
Copyright (c) 2024 Agustín Quesada, Melina B. Paez, Nicolás M. Bistolfi, Ana P. Blazina, Mariano M. Amoroso https://creativecommons.org/licenses/by-nc/4.0
Copyright (c) 2023 José I. Cuitiño, Giorgio Basilici, M. Sol Raigemborn https://creativecommons.org/licenses/by-nc/4.0
Soil-geomorphic relationships in a northeastern Patagonian tidal salt marsh, Península Valdés, Argentina
Salt marshes ecosystems have been studied extensively based on the interaction between geo-morphological and geo-ecological processes, but a soil-geochemistry approach is currently unknown in Patagonia. This work was conducted in Riacho salt marsh, Patagonia, Argentina, and, its aim was to establish the soil-geomorphology relationship with a focus on geochemical analysis and vegetation changes (C3 vs. C4 photosynthesis pathway plants). The geochemical analysis was focused on sulfidic material occurrence and their potential acid generation, while the vegetation-geomorphology relationship was determined through the ?13C composition from soil organic matter. To achieve this, soil descriptions and laboratory analyses of soil samples were performed. Riacho salt marsh soils correspond to the Entisol Order and the Suborder Aquents. Soils corresponding to Sarcocornia perennis and Limonium brasiliense vegetation units were classified as Sodic Hydraquents, which were associated with tidal flats between Holocene beaches-ridges systems. On the other hand, the soil corresponding to the Spartina alterniflora vegetation unit was classified as Haplic Sulfaquents related to salt marsh lower levels, where waterlogging soil conditions favor the sulfidic materials formation. These soils are considered potential acid sulfate soils (PASS) due to the generation of sulfuric acid by oxidation processes. Consequently, extreme oxidation of these soils could release metals. The ?13C isotope composition of soil organic matter, in combination with the C/N ratio, indicates that the sandy C horizons from soils corresponding to high salt marsh levels would constitute pioneer salt marshes, which is consistent with the Holocene salt marshes development. The plant zonation model responds to ecological succession according to geomorphology evolution. However, future isotopic studies will be necessary to determine the contributions of different sources, both surface runoff of organic matter from continental ecosystems and organic matter from marine origin.
Copyright (c) 2023 Ileana Ríos, Pablo José Bouza, Alejandro Bortolus, Yanina Idaszkin, Nicolás Scivetti https://creativecommons.org/licenses/by-nc/4.0
Origin and evolution of coastal lagoons from the pampean region: Mar Chiquita, Las Brusquitas, Reta (Buenos Aires province, Argentina)
Low-lying coasts are specially conditioned for the origin and development of coastal lagoons. The Pampean region (Buenos Aires, Argentina) contains the surplus of a sea level fluctuation that occurred during the last 6000 years. This report studied three coastal lagoons at different stages of their evolution: Mar Chiquita coastal lagoon, Las Brusquitas estuarine lagoon, and the small coastal lagoon of Balneario Reta. The long-term evolution is considered in the case of Mar Chiquita and Las Brusquitas, while modern trends are also described for the Mar Chiquita silting problems and the urbanisation of the Reta village surrounding the lagoon. The study is based on radiocarbon datings, salinity analyses and sedimentological studies on both outcrops and piston cores. At Mar Chiquita coastal lagoon, a shallow open bay has been restricting since the Middle Holocene, causing the development of marshes and tidal flats between cheniers and regressive spits. Its evolution is therefore conditioned to high-energy events that reworked bioclastic sands (cheniers and regressive spits) and the silting of fine sediments. The sequence outcropping at the outlet of the Las Brusquitas creek extended temporally between 6190 and 2380 14C years BP; the estuarine lagoon was located at the outlet of two creeks. New outcrops exhumed and radiocarbon datings indicated this new interpretation of the site as an estuarine lagoon silted in the last 2000 years. The small estuarine lagoon (“microalbufera”) of Balneario Reta is another wetland flooded by the increase in water discharge due to artificial channels. Their connection to the sea depends on the effects of maximum tides and winds blowing from the south. The contents in diatom assemblages were interpreted as indicators of changes in salinity balances during the Late Holocene. Oligohaline specimens dominated at the three coastal lagoons; polihaline and mesohaline assemblages characterise some intervals at the Mar Chiquita and Las Brusquitas sedimentary sequences. In order to preserve these coastal lagoons and the natural reserves related, it is necessary to preserve their dynamics according to forecasted sea level rise, and the water balances between salt and fresh waters.
Copyright (c) 2024 Federico Ignacio Isla, José Bedmar, Camilo Vélez Agudelo, Luis Cortizo https://creativecommons.org/licenses/by-nc/4.0
Recent disturbance events recorded in the sedimentary infill of Lago Guillelmo (Argentina): tephra falls and hydrogeomorphic processes
We studied two natural disturbances that affect the Parque Nacional Nahuel Huapi area: tephra fall events from Andean volcanoes and hydrogeomorphic processes within catchments related to heavy rains. We carried out a surface analysis, describing the main morphometric features of the selected watershed, informally called La Cantera watershed; analyzing satellite images and historical aerial photographs; looking for evidence of processes related to these disturbance events in the watershed and morphological changes in the alluvial fan generated over the delta. The subaqueous environment was analyzed through bathymetries, sediment cores, and Ground Penetrating Radar (GPR) profiles, taken in the distal deltaic environment of the watershed. In the sedimentary record of the lake, we identified 12 tephra layers deposited in the last 200 years, attributed to Cordón Caulle, Calbuco, and Osorno volcanoes. These were chronologically correlated with previously documented eruptions of these volcanic centers, using vitroclast morphology, mineral association, and stratigraphic position. We also identified 10 epiclastic layers corresponding to sediments with terrigenous components and terrestrial organic matter, interpreted as hyperpycnites. We assign two hyperpycnite deposits to a debris flow that occurred in the area in February 2015 that caused several damages and roadblocks, based on the stratigraphic position of these deposits in the cores, and the identification of sediments associated with this event on the lake surface in satellite images. After the correlation between the GPR radargram units with the lacustrine cores, we associated one major radar unit with a (1) tephra layer and (2) lobe-shaped morphologies, interpreted as a hyperpycnite deposits, located in front of the outflow of an abandoned river course. The results allow inferring a significant anthropic impact in the lacustrine record, as a result of the construction of Route 40 and gravel mining activities after 1969 that affected the distal drainage network of the La Cantera watershed, generating topographic lows that make it difficult for subaerial flows to reach the lake. This work shows the importance of the integration between subaerial processes that occur throughout a basin with the underwater processes that take place in the deltaic environment, to understand the extension and characteristics of these natural disturbances.
Copyright (c) 2023 Pablo Amat, Gustavo Villarosa, Débora Beigt, Valeria Outes, Julieta Cottet, Lucia Inés Dominguez, Alex Cottescu, Andres Barbosa https://creativecommons.org/licenses/by-nc/4.0
ONE WORM IN THREE SUBSTRATES, NEOICHNOLOGICAL ANALYSES OF U-SHAPE STRUCTURES IN THE GOLFO NUEVO BEACHES, PATAGONIA, ARGENTINA.
The environmental analysis of the sedimentary record use different tools to characterized not just the main physical parameters of a sedimentary systems, also the development of life on it. Neoichnology, is an actualistic view of how the organisms are connected with the place where they live, providing modern models and ideas that serve as analogous. Many of the (neo)ichnological literature is concentrated on the Northern Hemisphere, and it is little known what happens southern the tropics. The description of organisms that lives either in hard- and soft-grounds is strange, and its description can help to interpret the paleodiversity in the fossil record. At Chubut province (Patagonia), in the Golfo Nuevo lives a polychaete that inhabits at the same time rocky abrasion platforms and sandy intertidal sediments. The present short-note is intended to described this occurrence and discuss its importance to ichnology.
Copyright (c) 2023 Sebastian M. Richiano, Bernardina Richiano Dellatorre https://creativecommons.org/licenses/by-nc/4.0
Olistoliths of the Gualcamayo Formation (Middle Ordovician) embedded into the Silurian-Lower Devonian Rinconada Formation, Eastern Precordillera, Argentina: paleontological, stratigraphic, and basin-model implications
This contribution provides new paleontological and stratigraphic data for the Eastern Precordillera (San Juan province, Argentina) Ordovician basin. This is based on the description of a group of olistoliths, interpreted herein as coming from the lower beds of the Ordovician Gualcamayo Formation, found embedded within the matrix of the Silurian-early Devonian Rinconada Formation. These olistoliths are characterized by variable dimensions and uniform lithologies, composed of black shales and marlstones or following hectometric limestone blocks related to the San Juan Formation. The Gualcamayo Formation blocks show a graptolite fauna characterized by Holmograptus spinosus, H. bovis, Cryptograptus schaeferi, Paraglossograptus tentaculatus, Archiclimacograptus spp., Atopograptus sp., Pseudophyllograptus sp., Tetragraptus sp., and Xiphograptus sp.; whereas on the bedding plane surfaces, conodont elements of Histiodella sp., Paroistodus horridus, Periodon macrodentatus, and Protopanderodus sp. are found. In the interbedded black shales-marlstones, the trilobites Annamitella sp., Mendolaspis sp., and Carolinites? sp. are observed. The presence of this graptolite fauna allows recording the middle Darriwilian H. spinosus Zone, representing the third record in South America, and enabling a correlation with other outcrops of Precordillera and North America, Australasia, and China. These middle Darriwilian deposits at the La Rinconada section represent the youngest age ever recorded for the drowning phase of the Ordovician carbonate platform (locally referred to as transfacies). This is coherent with a progressive drowning model from north to south and agrees with the diachronism of the base of the Gualcamayo Formation and equivalent units. In addition, the difference between the underlying units of the Rinconada Formation in different sections, together with contrasting thickness measurements, might indicate evidence of the Alto del Tambolar tectonic activity during the Rinconada Formation accumulation in Eastern Precordillera. These processes were also previously recognized for the deposition of the Tucunuco Group in the Central Precordillera. This study expands the knowledge regarding the carbonate drowning process of the Precordillera basin that occurred during the Middle Ordovician and the effects of the Guandacol Tectonic Phase in the La Rinconada area, never mentioned until this moment.
Copyright (c) 2023 Fernando Enrique Lopez, Osvaldo Agustín Conde, Alejandro Raúl Braeckman, Lautaro Estrada, Cintia Kaufmann, Juan Martín Drovandi, Fernando Ariel Pedernera, Ulises Abarca, Jonatan Ariel Arnol https://creativecommons.org/licenses/by-nc/4.0
Volcaniclastic sediment input and environmental responses of fluvial systems: exploring a Cretaceous example from Patagonia
The input of large volume of volcaniclastic sediments causes significant changes and imbalances in natural systems, with the consequent readjustment of depositional environments. In fluvial systems, it can affect the hydrogeomorphology, sedimentation, composition of detritus, soil features and ecosystems. Consequently, the changes detected in the sedimentary record are usually linked with volcaniclastic sediment supply, mainly in near vent positions as aprons. In this context, a specific Cretaceous stratigraphic interval of the Somuncurá-Cañadón Asfalto Basin, Argentina, offers the possibility of testing the temporal evolution of a fluvial system to a large influx of volcaniclastic material from a distant source. Particularly, we analyzed the upper Bardas Coloradas and Puesto La Paloma Members, which belong to the Los Adobes and Cerro Barcino Formations respectively, in Los Chivos hill and surrounded area. The goal of this contribution was to evaluate in detail the paleoenvironmental evolution registered in these units, as well as the link with all allocyclic controls on sedimentation. Seven facies associations were defined including low sinuosity fluvial channel (FA1), meandering-like crevasse channel (FA2), splay (FA3), distal floodplain (FA4), aeolian (FA5), sheet-floods (FA6), and feeder channel (FA7). They were positioned into three informal stratigraphic intervals denominated A to C in chronological order of deposition. The stratigraphic interval A (upper Bardas Coloradas Member, 35 m thick) includes low sinuosity fluvial channels which transported a permanent sandy bedload towards the NW; and vegetated floodplain zones characterized by the presence of meandering-like crevasse channels, splays and shallow lakes or ponded zones. The stratigraphic interval B (lower Puesto La Paloma Member, 11-16 m thick) records a volcaniclastic-rich aeolian system composed of 2D aeolian dunes that migrated towards SE and were spatially related to wet- and dry-interdune zones where the sedimentation mostly occurred from subaqueous and subaerial settling of suspended volcaniclastic sediments, respectively. The stratigraphic interval C (upper Puesto La Paloma Member, 6-18 m thick) registers volcaniclastic-rich fluvial sedimentation characterized by unconfined flows, which were sediment-laden or diluted, and showing lateral relationships with ponded areas. Locally, there was a feeder channel that transported volcaniclastic gravels towards the NW. The assessment of allocyclic controls suggests that the volcaniclastic sediment supply governed the changes in the depositional system without important influence of tectonic activity, climatic changes, eustatic sea-level modifications and basement morphology.
Copyright (c) 2024 Pablo Villegas, Aldo Martín Umazano https://creativecommons.org/licenses/by-nc/4.0
Influence of a piedmont foreland morphostructure on the development and configuration of alluvial deposits in the western piedmont of the San Luis range. San Luis, Argentina
El piedemonte occidental de la sierra de San Luis, Argentina, está conformado por depósitos aluviales, agrupados en tres niveles pedemontanos (I-III), localizados a diferentes alturas y con relaciones de incisión entre ellos. El nivel I se corresponde con remanentes de abanicos aluviales disectados y adosados al knick serrano. El nivel II comprende cuerpos de abanicos aluviales con buena preservación morfológica. El nivel III no presenta características morfológicas bien definidas. Genéticamente, el piedemonte se vincula a la ladera occidental de la sierra de San Luis, que representa el escarpe de la falla homónima, de carácter inverso. El sector septentrional del área pedemontana describe una morfoestructura vinculada del corrimiento y progradación del frente de deformación principal hacia el interior de la cuenca, interpretada como piedmont foreland. Este contexto morfoestructural condiciona el espacio de acomodación de la cuenca sedimentaria y, en consecuencia, la geometría de los depósitos aluviales. A partir de los datos sedimentológicos, estratigráficos y geomorfológicos obtenidos en campo y laboratorio se realizó una caracterización geomorfológica y litoestratigráfica de los depósitos de abanicos aluviales del nivel II del piedemonte occidental de la sierra de San Luis. Los depósitos que caracterizan a este nivel aluvial se disponen en cuerpos de abanicos aluviales individuales con buen grado de preservación. Internamente están constituidos por conglomerados gruesos clasto-sostén con intercalaciones de litofacies arenosas gruesas y estratificación horizontal. En las zonas apicales predominan los conglomerados, correspondientes a depósitos de flujos hiperconcentrados no viscosos. En las zonas proximales y medias se reconocen litofacies conglomerádicas y arenosas interestratificadas, que corresponden a depósitos de fajas de canales someros de alta energía sin desarrollo y/o preservación de las llanuras de inundación. Hacia las zonas distales se reconoce un predominio de las litofacies arenosas, donde los depósitos de fajas de canales son de menores dimensiones y energía, y están asociados con depósitos de desbordamiento. A lo largo del piedemonte, el nivel aluvial II presenta variaciones que han permitido dividirlo en tres sectores. Los abanicos del sector norte tienen geometría aproximadamente tabular, con espesores de entre 2 y 4 m. Los abanicos del sector sur tienen geometría triangular, que se acuña hacia el ápice, con espesores de 4 m en las regiones proximales y hasta 300 m en las distales. En ambos casos presentan características geométricas que los diferencian de los típicos abanicos aluviales definidos en la literatura, vinculados generalmente a frentes de levantamiento con fallamiento normal. La geometría de los abanicos aluviales del sector sur, triangular y con acuñamiento hacia el ápice, se asocia al espacio de acomodación disponible en la cuenca, cuyo borde oriental está limitado por la falla de San Luis, inversa y progradante. Por su parte, la geometría tabular de los cuerpos del sector norte se asocia a una disminución del espacio de acomodación de carácter local, vinculado a la evolución de una morfoestructura de piedmont foreland.
Copyright (c) 2023 Jael Aranda, Guillermo Ojeda, Juan Matías Perón Orrillo https://creativecommons.org/licenses/by-nc/4.0
SPATIAL DISTRIBUTION OF THE HUACO MEGA FAN SEDIMENTARY FACIES, BERMEJO BASIN SAN JUAN ARGENTINA.
En los últimos años varios autores han considerado que los mega-abanicos están incluidos dentro de los Sistemas Fluviales Distributivos (SFD), los que, por su abundancia en los ambientes sedimentarios continentales y sus características geomorfológicas y sedimentológicas son considerados potenciales fuentes de recursos hídricos y energéticos. En este estudio se propuso obtener un modelo geomorfológico y sedimentológico del mega-abanico del río Huaco utilizando imágenes satelitales, análisis fotogeológico y relevamientos de campo. Con estos datos evaluar si el mega-abanico corresponde con el modelo de un SFD y, en caso de que lo sea, definir de qué tipo según las clasificaciones propuestas. El mega-abanico del río Huaco se localiza al Este de la provincia de San Juan en el valle del Bermejo, que es la cuenca de antepaís fragmentada de la faja plegada y corrida andina entre los 29° y 31° LS. A través del procesamiento de imágenes multiespectrales se reconoció la distribución de materiales a escala regional. El estudio geomorfológico permitió distinguir siete unidades geomorfológicas, determinar la sinuosidad de los canales fluviales y cambios de pendiente. A partir del análisis sedimentológico se obtuvieron las características texturales de las unidades geomorfológicas identificadas. Con estos criterios se definieron cuatro zonas principales: a) zona 1 o proximal, formada por un sistema fluvial multicanalizado de baja sinuosidad; b) zona 2 o media, formada por un sistema fluvial monocanalizado de alta sinuosidad; c) zona 3 o distal, formada por un sistema fluvial monocanalizado de baja sinuosidad; y d) zona 4, correspondiente a la región de interacción entre el mega-abanico del río Huaco, el río Bermejo y el río Jáchal. De acuerdo con las características estudiadas y las clasificaciones de SFD propuestas, el mega-abanico del río Huaco corresponde a un SFD de tipo entrelazado dominante y anabranching multicanalizado. Es importante destacar que la tasa de aporte de sedimentos en el mega-abanico no sólo se produce asociada a la acción fluvial, sino también a la acción eólica la que es muy importante, especialmente cuando las geoformas son abandonadas.
Copyright (c) 2023 Agustin Santamaria, Paula Santi Malnis, Matias Debandi Bertona , Luis Martin Rothis , Tatiana Soria Pures https://creativecommons.org/licenses/by-nc/4.0