This study presents the first surficial sediment zonation based on an analysis of backscatter data and sediment samples acquired during the YTEC-GTGM0 and AMPY1 (2017 and 2022, respectively) aboard the R/V Austral. Data were collected using a Kongsberg EM122 echosounder operating at 12 kHz, covering a 3882 km2 area that includes the Sloggett Submarine Canyon and its interfluve with Valentín Submarine Canyon, located within the ‘Yaganes Marine Protected Area’ in the Tierra del Fuego Continental Margin. A 75 × 75 m grid was generated from the backscatter data, and both supervised and unsupervised clustering algorithms were applied, resulting in four distinct acoustic groups. A qualitative analysis was performed to evaluate the suitability of each clustering method for dB value determination. The acoustic groups were then validated using nine surficial sediment samples collected from the study area. The results demonstrate a strong correlation between the extreme values of the dB scale and sediment types: lower dB values (< -26 dB) correspond to fine-grained sediments (silt and sandy silt), while higher dB values (> -18 dB) correlate with coarse-grained sediments (sand and gravel). However, intermediate dB values show poor correlation with specific sediment types, likely due to the influence of mixed sediments and geomorphological factors such as seafloor slope and subsurface layering. Notably, the seafloor slope above 7° was found to significantly influence backscatter values, highlighting the complexity of acoustic interpretation in steep environments. This study provides the first detailed classification of geohabitats in the AMPY, enabling the creation of a map that reveals three main seafloor types: fine-grained, mixed-grained, and coarse-grained that were associated with soft muddy, mixed, and hard and rugged geohabitats. The findings underscore the utility of backscatter data for seafloor characterization, particularly in extreme dB ranges, while also highlighting the challenges of interpreting intermediate values. This work contributes to a better understanding of the benthic environment in marine protected areas, supporting future conservation and management efforts.

With only four species, Pteridium is one of the most-known fern genera for its role as pioneer in ecological succession and for being an aggressive weed. Despite its current wide distribution that extends to almost the entire world, there is a relatively small number of fossil records of macrofossils and palynological assemblages related to or compared with this genus. The majority of these belong to Oligocene ─ Pliocene deposits from the United States, Europe, Asia and New Zealand and only one has been described for South America, in upper Pliocene? – Quaternary deposits from Brazil. In this contribution, we describe the oldest and southernmost record of Pteridium for South America, based on frond impressions from Miocene deposits of the Ñirihuau Formation, exposed in the North Patagonian Andes (Argentina) and interpreted as deposited in alluvial, lacustrine, deltaic, and fluvial environments. We illustrate the finding and compare it with previous records of Pteridium and Pteris and with the current Neotropical species Pteridium esculentum. Additionally, we characterise the palaeoenvironmental framework in which the palaeoflora developed and we discuss the association of the fossil with other taxa fossils found in the same deposits, and of Pteridium with other species in current floras.

The Cerrito Blanco de Arizaro Formation is part of the widespread Cenozoic volcanism in the Southern Puna region. It comprises three lava domes (Domes 1, 2, and 3) with subcircular to slightly elliptical shapes, emplaced on gentle slopes. Domes 1 and 2 lie east of the Aracar volcano, while Dome 3 is located east of the Vega de Arizaro. Dome 1 consists solely of coherent lava, whereas Domes 2 and 3 display both coherent lava and autobreccia facies. Petrographically, the rocks contain plagioclase, quartz, and biotite crystals within a glassy groundmass. All three domes exhibit flow foliation, marked by variations in vesicle abundance and distribution, indicating emplacement under laminar flow conditions. Geochemically, the domes are high-silica rhyolites with a calc-alkaline signature
and features suggesting intraplate magmatic affinity. Their silica-rich composition and low rare earth element (REE) enrichment imply advanced fractionation of phases such as hornblende, pyroxene, and accessory minerals. Compared to other rhyolitic bodies in the region, these domes are distinguished by a subtle negative Eu anomaly and moderate Sm/Yb ratios, consistent with crystallization at intermediate depths in the crust.

The Miocene Vinchina Formation (VFm) is the thickest sedimentary unit of the Vinchina Basin, an Andean broken-foreland basin in northwestern Argentina. Between 16 and 7 Ma, more than 10,000 meters of sediments accumulated in this basin. The sedimentology and compositional characteristics of the unit have been thoroughly studied. However, its diagenetic history is poorly understood. Based on the composition of authigenic minerals and their temporal relationships in seventy-eight sandstone samples, this study presents an interpretation of the diagenesis of the VFm sandstones. Petrographic observations allowed identification of authigenic minerals and their temporal and spatial distribution. X-ray diffraction (XRD) analyses helped differentiate zeolites and clay-mineral species. Using a scanning electron microscope (SEM) with an energy-dispersive spectrometer (EDS) permitted the identification of crystal morphology and the composition of the neoformed phases. Sandstones of the VFm exhibit a diverse arrangement of twelve authigenic minerals, calcite, zeolites, and gypsum being the most prevalent. Their distribution varies geographically throughout the basin due to paleoenvironmental facies distribution, framework clast composition, and diagenetic processes. Carbonate cements dominate the coarser-grained (fluvial) facies in the northern region. In contrast, gypsum is more conspicuous in the finer-grained (lacustrine and playa lake) facies prevalent in the basin’s southern sector. Accordingly, clay cements increase from north to south as sediment grain size decreases. The distribution of zeolite cements correlates with the quantity and nature of volcanic clasts. Analcime is abundant in the upper and lower sections and correlates with rhyolitic paleovolcanic clasts. Heulandite and laumontite are frequent in the central and northern areas linked to pulses of andesitic neovolcanic detrital contributions. Finally, deep burial and uplift control the alteration of the neoformed authigenic phases. That is the case of the gypsum to anhydrite, clinoptilolite–heulandite to laumontite, and smectite illitization transformations during the mesogenesis or the formation of secondary porosity during telogenesis. Compositional and textural characteristics of VFm sandstone cements were used to produce a diagenetic model to explain the various pathways, from eogenesis to telogenesis, which occurred in different parts of the basin. Altogether, diagenetic studies suggest that primary composition, depositional-facies distribution, and burial depth were major controlling factors during diagenesis.

The occurrence of the laumontite–quartz mineral pair in sandstones of the lower part of the VFm suggests that maximum temperatures may have reached a range between 139 and 162 °C. Depending on the sedimentary thickness considered, these values are consistent with either a 13.9 °C/km or a 30 °C/km geothermal gradient.

Thus, establishing a robust depth–time model that considers the effects of progressive unconformities is necessary to determine the basin’s paleogeothermal gradient accurately.

The development and emplacement of magmatic bodies during the Middle Paleozoic along the western margin of Gondwana remain poorly understood. To better constrain the nature of these processes, petrographic, anisotropy of magnetic susceptibility (AMS), anisotropy of anhysteretic remanent magnetization (AARM) and rock magnetic studies were performed in 326 specimens from 23 sites on Late Famennian—Early Tournaisian (∼357 Ma) basic dike swarms exposed at the Cuesta de Miranda (29°20′26″S; 67°46′3″W) and the Cosme Creek (29°15′27″S; 67°53′4″W) localities in the southwestern Famatina System, La Rioja province, Argentina. AMS results reveal that in the Cuesta de Miranda area, the maximum anisotropy axis (K1) is in a sub-vertical position, while in the Cosme Creek, it is dipping ∼40° towards the ESE, parallel to the strike of the dikes. Rock magnetic studies suggest that magnetite is the main mineral contributing to susceptibility. AARM studies confirm that the main axes of the susceptibility ellipsoid given by the AMS correspond to a “normal” fabric. The obtained results allow us to propose an emplacement model, in which the magmatic source that originated the dikes of the Cuesta de Miranda area was located under this region leading to a vertical flow of the magma at this locality. In the Cosme Creek, magma emplacement occurred due to an oblique upward flow that migrated around 15 km towards NW. In this area, all dikes exhibit similar AMS patterns despite petrographic differences among them. This suggests the emplacement of different magma pulses controlled by pre-existing regional structures.

The temperate grassland and cultivated soils of the Western Pampa of Argentina, southern South America, developed over Late Pleistocene–Holocene aeolian sands, shifted from semiarid to dry subhumid in the past ~120 years with an increase of precipitation variability, concordant with significant changes in agricultural land use. This Western Pampean Dunefield (WPD) is a dormant system, mostly stabilised by vegetation and agriculture, with extensive reactivations during the 1930s ‘Pampas Dust Bowl’ and the current formation of new dunes in an anthropogenically disturbed landscape. Analysis of the complex assembled aeolian landforms of the WPD with quantification of vegetated dunes provides new associations for landscape evolution and aims to contribute to science-based land management. The methodology includes field surveys, remote sensing imagery, dune morphometry, site stratigraphy and optically stimulated luminescence (OSL) dating. Main aeolian bedforms are blowout dunes and sinuous ridges, associated with aeolian streaks, sand sheets and fluvial-aeolian plains. The blowout dunes (simple, compound and complex) reach tens to thousands of meters in diameter, have commonly superimposed dunes on the depositional lobes, and sand transport directions towards the NW, NNW-NNE and SW. The sinuous ridges, continuous for 100s m to 1–2 km, have nearly symmetrical profiles and two main crest orientations (NW-SE and SW–NE). Cross-dune patterns and associated OSL chronology allow proposing a morphostratigraphy scheme of compound and complex blowout dunes developed during the Late Pleistocene and growing since then, while sinuous ridges probably accreted in the Holocene. Young blowout dunes are penecontemporaneous and post-date sinuous ridges, reflecting significant aeolian reworking processes. Patches of barchanoid and reversing dunes superimposed on blowout dunes, which have been active since at least the CE 1970s, and the new dune formation in the past two decades, often in intensively cultivated areas, indicate that synergistic biogeomorphic processes may yield irreversible changes in semi-arid to dry subhumid landscapes with an aeolian legacy.

Permian times were characterized by distribution of land masses forming a supercontinent called Pangea. Although its existence has been accepted for many decades, there is still debate about its configuration. In order to provide new constraints on the position of Gondwana during late Paleozoic times, a paleomagnetic study was carried out on Carboniferous-Permian red beds exposed in the Famatinian Ranges, western Argentina (27°43′S 67°58′W). Eighty four oriented samples (11 sites) were submitted to standard stepwise demagnetization procedures. Magnetic analysis was complemented by acquisition of isothermal remanent magnetization (IRM), backfield curves and anisotropy of magnetic susceptibility (AMS) on selected specimens. Inclination shallowing due to compaction was evaluated by application of oriented acquisition of IRM and demagnetization experiments. The high-temperature magnetic components of sites are characterized by southward declinations with positive inclinations that yield a positive fold test. A new paleomagnetic pole is calculated and suggests an age of magnetization between 300 and 270 Ma, thatmatches with a Pangea B distribution although a Pangea A2 model can not be ruled out if the magnetization age is restricted to 280-270 Ma.

A detailed geological study of the Guando oilfield has identified a modern landslide phenomenon that significantly alters the previous structural model and affects production challenges. The multi-compositional nature of the oil-bearing Cretaceous sequences of the Villeta Group, the rugged relief, the climatic incidence, and seismic activity in the Upper Magdalena Valley trigger the Guando Slump, which adjusts the topography to levels of greater stability. The previous tectonic model of the Guando oilfield was based on the superposition of an internally disturbed block by the Boquerón thrust. However, in its westernmost segment, this structure shows angular incompatibilities with the expected horizontal stress fields. Therefore, based on a detailed 3D interpretation of geological maps, DEM, and available geophysical data, we propose that this segment must be associated with the surface of the underlying detachment of the Guando Slump. The horizontal displacement of the landslide, ranging from 1 to 2 km, deforms and collapses the wells that reach the underlying productive reservoirs. This study describes the relationship of this new tectonic model of the Guando oilfield, considering the westernmost segment of the Boquerón thrust as a detachment of the Guando Slump. This real-life example, if properly monitored, will contribute to a better management of the possible causes and consequences of technical problems encountered in the Guando oilfield exploration and prevent catastrophic risks to the production facilities.

As humans expanded across the globe, the Americas were the last continents to be colonized. While debates persist regarding the timing and mechanisms of this process, it is widely accepted that by the Pleistocene–Holocene transition, the New World was populated from Alaska to Tierra del Fuego. During this period, hunter-gatherer societies demonstrated remarkable cultural and adaptive diversity, particularly in subsistence strategies and technological innovations. The colonization of the Americas offers valuable insights into population dynamics, human–environment interactions, species extinctions, and adaptive capacities. From an interdisciplinary perspective that combines an isotopic analysis of megafaunal remains with archaeological evidence, this study examines human interactions with Pleistocene fauna in the south–central region of South America’s Southern Cone. Isotopic analyses provide information about the diets, adaptations, and climatic challenges faced by megafaunal communities. Archaeological evidence reveals that humans utilized megafauna and other Pleistocene species for food and tool production. These findings are supported by evidence such as cut marks and bone tools, but also by sealed sediment layers and/or indisputable associations of lithic artifacts. This research contributes to our understanding of human dispersal in the Southern Cone during the colonization of the Americas, shedding light on the regional environments and adaptive strategies of early populations.