A new Permian lithostratigraphic unit denominated Puerta de Las Angosturas Formation is defined for the Paganzo Basin. The new formation is mainly composed of variegated mudstones and sandstone beds, among which several levels of chert, limestone, and tuff are interstratified. The area of Las Angosturas (Sierra de Narváez, Catamarca province) is set as its type section, in which six stratigraphic intervals were distinguished and described. Stratigraphic interval 1, formed by massive or laminated red and purple sandstones (23 m thick), overlies eolian deposits belonging to the De La Cuesta Formation through a low-relief erosive unconformity. Interval 2 comprises 55 meters of purple to grayish-brown mudstones and fine-grained sandstones that transitionally cover interval 1 or overlap on the red beds of the De La Cuesta Formation. Interval 3 is made of interbedded sandstone and limestone beds with millimeter levels of chert; the whole interval reaches 110 m of thickness. Interval 4 (70 m) shows similar lithological characteristics to 3 but differs in the predominance of mudstones over sandstone and the presence of thin and recurrent tuff levels. Interval 5 is very thin, 35 m thick, and shows marked lithological changes concerning those previously described intervals since it is formed by medium- to coarse-grained cross-bedded sandstones. Finally, interval 6 (76 m) corresponds to a fine-grained sequence in which mudstones, very fine-grained sandstones, limestone, and a few tuff beds alternate. The Puerta de Las Angosturas Formation is covered in unconformity by the red beds of the Talampaya Formation. Intervals 2, 3, and 4 of the Puerta de Las Angosturas Formation have provided palynological assemblages corresponding to the Lueckisporites/Weylandites biozone that suggests a Kungurian age, at least for the lower half of the unit.

This paper analyzes an extended eolian field developed during the Oligocene-Early Miocene along the eastern flank of the Andes. This eolian episode, herein named OMEB (Oligocene-Miocene Eolian Belt), is recorded in several units, including Mariño, Pachaco, Cuculí, Vallecito, El Crestón, Tambería, Angastaco, Quiñoas, Las Chacras, and Vizcachera Formations. Eolian accumulation occurred in five environments: 1. Sand sheet and extradune, 2. Dune field, 3. Dune and draas, 4. Deflationary eolian fields, and 5. Wadi and fore-eolian areas. While sand sheet deposits are composed of horizontally laminated and low-angle cross-bedded sandstones, dune and draas environments comprise giant- and large-scale cross-bedded sets and dune fields by stacked sets of cross-bedded sandstones. In contrast, the deflation field environment exhibits low-relief irregular surfaces carved in dune and extradune environments. Finally, the wadi and fore-eolian deposits correspond to the eolian dune interbedded with fluvial conglomerates and muddy sediments deposited mainly by low-energy fluvial currents on the interdunes. Towards the end of the Early Miocene, the OMEB declined in almost all the foreland area, and fluvial and lacustrine sediments replaced eolian deposits. Although the stratigraphic expression of this change was different along the region, three principal patterns of change are recognized: 1. Different degrees of fluvial incisions, 2. Fluvial replacement of eolian deposits without evidence of significant incision, and 3. interbedding of eolian, fluvial, and occasionally playa-lake deposits. In the first pattern, conglomerates forming lenticular channels abruptly incise into the dune deposits. In pattern 2, fluvial channels are dominantly sandy, and incision surfaces are poorly defined. The third pattern, contrasting with the two previously described, results from the recurrent interstratification of eolian, fluvial, and playa lake deposits. This type of eolian-fluvial transition was studied in detail in the Tambillos creek (Northeastern Sierras de Los Colorados), where a sequential model for the eolian fluvial transition using the position of the water table is proposed. This model allows defining four primary states: 1. Low water table, 2. High water table (below the surface), 3. High water table (at or slightly above the surface) with partial flooding and damming, and 4. Runoff for fluvial channels.

This paper presents a new U–Pb zircon age of 253.40 ± 1.06 Ma for the middle part of the Talampaya Formation, which is consistent with the previously reported dating of 252.38 ± 0.22 Ma at the top of the unit. The age herein presented was obtained from a tuff level intercalated into a fluvial sequence formed by finning-up cycles of massive conglomerates, cross-bedded sandstones, and laminated sandy mudstones interpreted as deposited by sandy meandering rivers with dominant sandy floodplains. In this context, a vitric tuff from a floodplain located 140 m from the base of the unit provided the zircons dated by the combination of LA-ICP-MS (Laser Ablation – Inductively Coupled Plasma – Mass Spectrometry).

The radiometric age of 253.40 ± 1.06 Ma confirms the relocation of the Talampaya Formation in the Late Permian and demonstrates that at least the upper half and probably the whole of this unit was deposited during the Lopingian, a time interval scarcely represented in South America. This assumption is consistent with the age of 249.66 ± 0.11 Ma (early Triassic) reported in the overlying La Veteada Formation.

The new age presented has paleoclimatic implications regarding the worldwide climatic aridification event that occurred at the end of the Late Paleozoic since it gives a relatively precise approximation to the onset of the aridization in this part of Gondwana during the Lopingian (circa 252.38 Ma).

Analysis of high-resolution seismic profiles from the central Beagle Channel enabled the recognition and characterization of several post-glacial subaqueous mass transport deposits in the subsurface of Bahía Ushuaia, offshore the city of Ushuaia (Argentina). These deposits are located at different stratigraphic levels and are embedded in the stratified sedimentary sequence within a deep trough, suggesting a recurrent occurrence. Up to eleven deposits have been identified, with four major events that involved estimated sediment volumes ranging from 12 to 57 million m3. The latter are associated with megaturbidite deposits up to 10 m thick. Two of the largest events postdate the early Holocene unconformity of marine transgression. The seismic data suggest a different dynamic behaviour of these four main events, with erosional, strongly disintegrating and longer-lasting pre-marine transgression mass transport events compared to the post-early Holocene deposits. Several of the deposits appear to have a common origin due to earthquake-induced failures of submerged glaciofluvial deposits or from tributary deltas. In addition, a preliminary analysis of the potential generation of tsunami waves associated with the largest submarine failures was carried out using numerical models. The results show that at least three of them would have the potential to generate dangerous waves with maximum heights of up to 1–2 m in the port of Ushuaia and estimated run-up heights between 2 and 8 m. Although further detailed analysis is recommended, particularly with regard to a more sophisticated modelling approach and refinement of the resolution of bathymetric and topographic data for strategic areas.

The tungsten-bearing veins of San Román and La Puntana mines constitute a series of quartz biextended bodies along about two km with potencies of the sub metric order that were exploited between the 40s and 70s through trenches and subsurface works. They are arranged in parallel on the contact of the metamorphic host of the San Luis Formation with the La Escalerilla Granite assigned to the lower Paleozoic, both units of the crystalline basement of the Sierra de San Luis. It is proposed that volumetric changes occurred during its late emplacement favored thermotectonic phenomena linked to the structural control of the mineralization by developing potential spaces subparallel to the vicinity of its controlled contact by the pre-existing planar anisotropies of its shale host rocks. In addition, the differential thermal contraction of the quartz during the passage from b to a, with respect to the other mineralogical constituents of the granite dome, produced during its cooling, a decrease in pressure with boiling of the pneumatolytic hydrothermal fluids enriched in immiscible elements. This mechanism generated in the domes of the La Escalerilla granite porosity and the concentration of fluids enriched in tungsten that migrated towards the overlying veins with a significant absence of greissinification and pegmatization. It is proposed that the power of the veins is related to the volumetric decrease of the intrusive throughout its contact and that they tend to thin out as they move away from the contact of the intrusive body.

The Punta Rasa Natural Reserve encompasses a system of small coastal lagoons, which are developed in a sand spit that limits with the coast of the southern end of the outer estuary of the Río de la Plata. The aim of this work is to estimate the discharge flow of groundwater from the environments of beach ridges and dunes adjacent to the coastal lagoons and evaluate how it influences the hydrochemistry of the associated lagoons and marshes. For this, a monitoring network was defined covering sampling points in the sea/estuary, coastal lagoons, and groundwater located in transects that perpendicularly cross the main body of the coastal lagoon. In each transect, water levels, pH, electrical conductivity, and 222Rn were measured in situ and samples were collected to determine the major ions. The analysis of groundwater flow profiles and 222Rn values allowed the identification of the existence of groundwater discharge flows in the three coastal lagoons. It was also possible to estimate the different components of the groundwater discharge flow and the velocity and discharge flows. Regarding chemistry, although coastal lagoons and marsh water are saline and show Na-Cl hydrochemical facies that reflect tidal flow contribution, in the areas of groundwater discharge from the dunes and beach ridges there is a decrease in the electrical conductivity of the marsh water associated with an increase in the concentration HCO−3+CO−23. This is because the water from the dunes and beach ridges is fresh to saline and has higher concentrations of HCO−3+CO−23 than sea water. Hydrodynamic differences in the three lagoons are associated with the relationship between tidal flow contributions—groundwater discharge responds to morphological changes owing to the evolution of the sand spit that encompasses the lagoons.

Our recent echo-character analysis of the Tierra del Fuego Continental Margin, focusing on Sloggett Canyon and the interfluve with Valentín Canyon, provides insights into contemporary sedimentary processes. Utilizing high-resolution seismic profiles obtained from the R/V Austral in 2017, we categorized sub-bottom echoes into 10 distinct types, shedding light on various processes such as hemipelagic deposition, mass wasting events, glacial influence, and the impact of bottom water masses. By integrating data from the GLORYS12V1 model (1993–2020), CTDs from the World Ocean Database, and sediment samples, we analyze the interaction between bottom currents, seafloor topography, and sediment characteristics. We conclude that the flow of the Subantarctic Water Mass acts as an active transport of coarser sediment from the continental shelf into the canyon, maintaining the Sloggett Canyon's activity, while the flows of the Upper and Lower Circumpolar Water Masses contribute to contourite formation along the eastern canyon flank and the erosion of the lower interfluve, leading to the generation of distinctive longitudinal scours. Additionally, in the continental rise, the interaction of water masses with the seafloor influences the redistribution of the deep-sea fans from the Sloggett and Valentín canyons towards the northeast. This study significantly enhances our understanding of the sedimentary dynamics in this area, establishing the basis of the sedimentary distribution for future interdisciplinary studies and for setting a new baseline in marine protected areas.

Stabilized and active dunes and sand sheet deposits abound in a small lake-dotted semi-arid region of the Western Pampean Dunefield, Argentina. Here, a multi-scale and multi-proxy study of three sites, across a hydrologic gradient from lakes to a dryland with groundwater levels at more than 25 m depth, analyzes calcareous and ferruginous rhizoliths, calcareous crusts, hypocoatings, pedogenic carbonate and amorphous Mn-oxide precipitates within blowout dunes. These palustrine-related features indicate significantly wetter conditions that allowed the development of shallow lakes and expanding wetlands during the Pleistocene–Holocene transition, limited by associated optically stimulated luminescence ages between ca. 14.7 and 11.6 ka. These wetter conditions, also identified in other nearby proxy records, may be associated with a strengthened South American Monsoon System, potentially during the Younger Dryas Chronozone, though other geological, ecological and climatic forcings cannot be ruled out with available data. Such a scenario lacks a modern analogue, since current hydrologic excess, evidenced in the formation of lakes and new rivers, is not observed in the localities which record paleolakes. This study underlines the variable conditions for pronounced hydrologic excess in semi-arid eolian environments in western Argentina with complex ecological, anthropogenic and climatic linkages.

We present a projectile point recovered from the archaeological locality of El Alto, province of Córdoba, Argentina. Its techno-morphological characteristics and the raw material used in its preparation are described. The results allow it to be included in the typological group of Fell projectile points. The data provided enrich the discussion about the first stages of occupation in the region, characterized by a meager archaeological record belonging to the final Pleistocene and the beginning of the Holocene.