Research Center on Earth Sciences

• Most Pampean arc granitoids show hybrid I-S-type compositions. • Zircon antecrysts (ca. 545 Ma) reveal long-lived arc magmatism (545–530 Ma). • Magma mixing dominates Pampean arc petrogenesis. The late Ediacaran to early Cambrian Pampean magmatic arc in Argentina represents an excellent example of subduction-related magmatism and continental crust formation. This study presents new geochemical, isotopic, and geochronological data from the Guasayán intrusive complex, which is a significant body within this magmatic arc. The data are integrated with a comprehensive compilation of published data from the arc elsewhere. The Pampean arc exhibits a wide range of rocks, from metaluminous I-type diorites to strongly peraluminous S-type granites, with the majority displaying hybrid compositions (mostly magnesian, calc-alkalic and slightly peraluminous compositions). Zircon U-Pb geochronology indicates that the Guasayán granitoids were emplaced mainly during a flare-up of arc magmatism between ca. 530 and 535 Ma. However, the presence of zircon antecrysts with ages of ca. 545 Ma in most of the Pampean arc granitoids, suggests that the magmatic system was long-lived, and the early crystallized zircon crystals were recycled into younger magmatic pulses. Geochemical and isotope data (Sr-Nd-Hf) highlight the interaction between mantle-derived magmas and crustal components, with magma mixing identified as the dominant process in the generation of the hybrid granitoids. Local-scale processes such as crustal assimilation, fractional crystallization, and peritectic entrainment also contributed to the geochemical and isotopic diversity. The involvement of the Puncoviscana Series as the crustal component of the mixed magmas is evidenced by zircon inheritance patterns and isotopic signatures. This study underscores the importance of magma mixing in the evolution of the Pampean arc and provides insights into the geodynamic processes driving continental crust formation in subduction-related settings.

This study examines in detail the impact of key post-curing parameters—temperature (39–80°C) and duration (11–140 min)—on the mechanical properties of castable wax resin V1 (a specialized material containing 20% wax). The material was fabricated using stereolithography (SLA) 3D printing, and the test specimens were prepared according to the ASTM D638–Type IV standard. Quantitative analysis (using response surface methodology) indicated that concurrent increases in post-curing temperature and duration result in a significant, statistically meaningful improvement in both maximum tensile strength and Young’s modulus. Specifically, the tensile strength increased from 12 MPa in the “Green State” up to 33.32 MPa (observed at 75°C – 120 min). Similarly, Young’s Modulus increased significantly from 220 MPa in the “Green State” up to 1155.26 MPa (observed at 60°C – 140 min). Conversely, the nominal strain at break decreases with increasing temperature. The strain at break decreased from 13% in the “Green State” to a minimum of 7.31% (at 60°C – 140 min), indicating that the material becomes harder but also more brittle. The study identified the optimal post-curing regime for achieving the highest mechanical performance of castable wax resin V1: a post-cure temperature of 80°C and a post-cure time of 140 min. The identification of these optimal parameters provides a solid scientific basis for optimizing the SLA additive manufacturing process. When applying the optimal regime (80°C and 140 min) in experimental jewelry casting, the results obtained were very positive. The resulting cast piece still reproduced the thinnest and most minor details, indicating that the casting pattern has high mechanical strength and resists external forces throughout the investment casting process without cracking or fracturing.

ABSTRACT This study provides a detailed ichnotaxonomic analysis of the Tin Tin Member (upper Oligocene – Lower Miocene) of the Angastaco Formation, north-western Argentina. These deposits represent a transition from ephemeral fluvial systems to the development of an aeolian system comparable to an erg. A total of 23 ichnotaxa have been identified across six facies associations, including 12 invertebrate, 9 vertebrate, and 2 plant trace fossils. The potential producers of each ichnotaxon are also analysed. Among the most notable discoveries are the oldest records of Nagtuichnus meuleni and Dolichotichnus marae, attributed to fossorial armadillos and cursorial rodents, respectively. Their presence in these deposits extends the known geographical range of the respective ichnogenera and, in the case of D. marae, represents the first record from aeolian dune deposits. The analysed trace fossils occur preferentially in aeolian dune deposits, which is in contrast with other known Palaeogene-Neogene examples of aeolian systems. The Tin Tin Member is distinguished by its high ichnodiversity and may serve as a valuable reference for future ichnosedimentological research in continental aeolian systems.

ABSTRACT Areas with aquatic ecosystems invaded by the American bullfrog face the challenge of managing its proliferation worldwide. This amphibian is native to eastern North America and is now invasive in several regions. This study reports a new invasive population in the Ctalamochita River basin (Río Tercero, Córdoba Province; Argentinian) and outlines its potential distribution using a species distribution model. Utilizing a MaxEnt model at a small geographic scale allowed us to explore the effects of local land use on the distribution of the species Aquarana catesbeiana . By combining 26 bullfrog records with 10 environmental variables, we identified coverage (coverage natural: pond coverage) as the most influential factor in the model. Our analysis also revealed positive associations between bullfrog presence and average annual precipitation, pH, percentage of sand, percentage of organic matter and distance from the nearest locality. Notably, our results demonstrate the significant role of humans as intentional dispersers of bullfrog. MaxEnt shows four most relevant areas, of which two: Río de Los Sauces to Villa Cañada de Álvarez and Villa Cañada de Sauce, are already colonized by the species. While the areas of Lutti and Cerro Pelado reservoir have a high probability of occurrence of bullfrog. Given the conservation significance of these areas, predicting the probability of bullfrog establishment is critical for risk assessment and conservation planning. Implementing control and monitoring strategies in Córdoba province is crucial to prevent bullfrog spread and mitigate environmental impacts in natural habitats.

Abstract In the Sauce Chico Complex (Neoproterozoic-middle Cambrian age; Ventania System, Argentina), polymetamorphosed carbonate xenoliths known as the Loma Marcelo skarn are hosted in an Ediacaran peraluminous granite. The skarn has three types of vesuvianite, namely a, b and c, with different colors, habits, and/or mineral assemblages. They were studied through petrographic microscopy, electron microprobe, inductively-coupled mass and atomic emission spectrometry, Raman and Mössbauer spectroscopy, X-ray (powder and single crystal) diffraction, and fluid inclusions and stable isotope analyses. The averaged composition of the Loma Marcelo skarn vesuvianite is XCa19.00Y(Al9.57Fe2+1.29Fe3+0.50Mg1.17Ti0.48Mn2+0.04)Σ = 13.05T□Z(Si18O68)W(OH5.79F3.03Cl0.28O0.90)Σ = 10.00 and corresponds to vesuvianite sensu stricto. Negligible amounts of XNa and TB were detected. Only Zn, Sr, Ce, La, and Sn are in concentrations >50 ppm. Through single-crystal XRD, the crystal structure of vesuvianite types a and b was refined in the P4/nnc space-group (domains with P4/n symmetry are also present). Type c vesuvianite could not be satisfactorily refined; however, a P4/n symmetry is suspected. By comparing the Loma Marcelo skarn vesuvianite cell parameters with those from other vesuvianites worldwide, it becomes clear that the symmetry does not influence such parameters. Based on Raman, single-crystal XRD data, and structural and chemical characteristics, formation temperatures of 550 °C (type b), 450 °C (type a), and 300–400 °C (type c) were estimated. δ18OH2O values of ca. +11.9‰ calculated for these temperatures from δ18O values determined on vesuvianite concentrates and the vesuvianite-water fractionation factors are compatible with a peraluminous granitic source. According to this, the Loma Marcelo skarn vesuvianite appear to reflect a retrograde process related to the crystallization of the Ediacaran granite hosting the metasomatized xenoliths. During a subsequent protracted Permian tectono-metamorphic event, biphasic secondary fluid inclusions were trapped at ca. 270–339 °C (ca. 250 MPa) from low salinity metamorphic fluids. Stable isotope determinations of H and O on vesuvianite concentrates indicate that the interaction with magmatic and metamorphic aqueous fluids promoted modifications in the 2H/1H ratios of the hydroxyl groups from the W sites, whereas the 18O/16O ratios of the silicate groups were not substantially modified. Notably, the vesuvianite structure is highly stable, remaining unchanged after formation. This stability suggests vesuvianite-group minerals could serve as a reliable XRD-based thermometer.