Instituto de Geociencias

Abstract A better understanding of the near‐surface aquifer system of the Caxambu Water Park, located in the Minas Gerais State, Brazil, has been achieved. The study aimed to identify groundwater reservoirs and flow patterns and contribute to the hydrogeological conceptual model using a multi‐scale geophysical approach. Audiomagnetotellurics and electrical resistivity tomography methods were employed, in addition to surface and structural geology. Structural contrasts at different depths were identified, allowing the characterization of the key geometric parameters of the aquifer system. The obtained geophysical models satisfactorily mapped the resistivity of the alluvial deposits, the crystalline basement and the base of the Caxambu Hill at depths of up to 200 m. The results revealed a distinctive brecciated groundwater reservoir containing conductive mineralized water beneath the mineral water springs of the Caxambu Water Park and the adjacent hill. Furthermore, it was possible to identify a deformation domain of the Caxambu Shear Zone that transports mineral water from depths greater than 190 m to the near‐surface fractured and porous aquifers. The presence of a conductor in the alluvial sedimentary layer indicates that the porous aquifer connects with the fractured aquifer and contains mineralized water. According to previous chemical and isotopic studies in the Caxambu Water Park, the original construction method of the water fountains prevents the external contamination. These results contribute to the sustainable exploitation of the resource and provide essential information for the effective management of regional water systems, ensuring the preservation of the therapeutic characteristics of the Caxambu water.

Our regional aeromagnetic study of La Palma Island (Canary Islands), based on conventional airborne data, successfully imaged the island's large-scale magnetic structure. While the magnetic data provided a robust regional framework, they lacked the spatial resolution required to investigate shallow volcanic structures and post-eruptive thermal anomalies following the 2021 eruption. Therefore, a high-resolution, drone-based aeromagnetic survey was conducted over the Tajogaite volcano, targeting the area most affected by the eruption.The survey was carried out in June 2024 and March 2025 using the DJI Matrice 210 RTK and DJI Matrice 300 RTK with a dual-sensor fluxgate magnetometer system sampling at 200 Hz. Constant-altitude flights covered an area of ~7 km2, with N-S-oriented survey lines spaced 30–60 m apart and tie lines spaced 150–200 m in the perpendicular direction. The drone flew in a lawnmower pattern, and we acquired high-altitude calibration flights in low magnetic gradient conditions to quantify and correct the magnetic measurements.Data curation involved several processing stages, including removing inconsistent flight tracks and compensating for platform-induced noise using the calibration data. The total magnetic intensity map and anomaly were obtained by applying gridding and smoothing to the signal and then removing the IGRF model.The resulting high-resolution magnetic anomaly map provides critical detail of the shallow magnetic structure of the Tajogaite volcanic edifice, allowing the identification of fault-controlled anomalies, low-susceptibility zones (after the 3D modelling of the data) related to high temperatures, and a potential shallow magma pathway.Additionally, we acquired new magnetotelluric data along a North-South oriented profile, perpendicular to the inferred still-hot dyke direction. This enabled us to construct a 3D electrical resistivity model that correlates with the magnetic model to further analyse this area, which is likely to be related to the final stage of magma ascension.This multidisciplinary research emphasises the importance of drone-based surveys in investigating active volcanic environments and post-eruptive dynamics on a local scale.

The Betic Cordillera of southeastern Spain experienced kilometer-scale surface uplift since the late Miocene, leading to widespread emergence of marine sedimentary units and contributing to the isolation of the Mediterranean Sea from the Atlantic Ocean at the end of the Miocene. Previous geophysical studies have linked this uplift to deep lithospheric processes, particularly the evolution and detachment of a subducted slab beneath the region. However, the geomorphic imprint of these processes across the Betic Cordillera has not been comprehensively characterized.Here, we investigate the landscape response to late Cenozoic uplift using quantitative geomorphic analysis. We combine high-resolution topography with river longitudinal profile analysis, knickpoint mapping, and river network metrics such as normalized channel steepness (ksn) and χ-values. This approach allows us to assess spatial patterns of landscape disequilibrium and to infer the evolution of surface uplift.Our results reveal a clear obliquity between the trend of maximum topography and the main tectonic structures of the Betics, a relationship that differs from other Mediterranean orogens. This anomalous elevation pattern spatially coincides with the region of lithospheric slab detachment previously identified by seismic tomography, suggesting a strong coupling between mantle dynamics and surface deformation. River profile metrics show strong contrasts in ksn and χ-values across the main drainage divide, indicating a transient, orogen-scale landscape and asymmetric erosion. These contrasts imply active migration of the principal drainage divide toward the Atlantic-facing basins, supported by the presence of wind gaps and river capture features.Knickpoint distributions further indicate increasing landscape disequilibrium toward the southwestern Betics, consistent with a laterally propagating uplift signal. Together, these geomorphic observations provide independent evidence for epeirogenic uplift driven by slab tearing beneath the Betic Cordillera, with westward propagation rates estimated at approximately 100–160 km per million years.This work is funded by GEOADRIA (PID2022-139943NB-I00) and MAPA (PIE-CSIC-202430E005) from the Spanish Government and the Generalitat de Catalunya Grant (AGAUR 2021 SGR 00410).

The land subsurface stored around 6% of the Earth’s energy imbalance in the last five decades (of around 0.5 Wm-2, equivalent to 380 ZJ), being the second contributor to the energy partitioning after the ocean (90%). Previous studies have shown that state-of-the-art Earth System Models (ESMs) remarkably underestimate the observational land heat uptake values. This underestimation stems from Land Surface Models (LSMs) within ESMs imposing too shallow zero-flux bottom boundary conditions to correctly represent the conductive propagation and land heat uptake with depth. When realistically deep boundary conditions are prescribed, land heat uptake increases by a factor of five. However, changes in ground surface temperature are negligible. The reasons for this lack of impact of the LSM depth on surface temperatures are assessed herein.An ensemble of eight historical and RCP8.5 land-only simulations with different subsurface depths was conducted with the LSM of the Max Planck Institute for Meteorology ESM (MPI-ESM), JSBACH. Simulation-derived latent (LHF), sensible (SHF), and ground heat fluxes (GHF) were compared across simulations, and GHF was additionally evaluated against estimates from a one-dimensional heat conduction forward model. Results show that, for a global warming of 1.5 ºC with respect to 1850-1900, GHF increases from 0.04 to 0.07 Wm-2 when deepening the LSM from 10 to 22 m, saturating at around 0.12 Wm-2 when the boundary condition is placed at approximately 100 m. The increase in the incoming GHF is mainly compensated by a global decrease in the outgoing SHF, a small decrease of the LHF in wet regions, and a decrease in the surface net radiation in arid and semi-arid regions. These quantities, yet small, evidence that an insufficient LSM depth induces to an inaccurate resolution of the long-term surface energy balance, which may have implications for land-atmosphere interaction. Their accumulation over time also produces biases in the terrestrial energy partitioning.

The Rheic ocean is one of the many oceanic basins inferred to form part of the intricate puzzle of continents and microcontinents in the Paleozoic. It opened in the Early Ordovician, separating the microcontinent Avalonia from Gondwana, and subsequently closed in the late Paleozoic with the amalgamation of the supercontinent Pangea, playing a major role in the Variscan orogeny. The existence of the Rheic ocean is accepted and required in plate reconstructions. However, its actual width, along-strike length, and relationships with other oceans and seaways (e.g., the Rhenohercynian, Galicia-Moldanubian, Saxo-Thuringian oceans) are unconstrained and controversial.To address these issues, we perform a detailed review of available data on lithostratigraphy, magmatism, geochronology, geochemistry, structural geology, and metamorphism of tectonostratigraphic units in Iberia and the British Isles, where the Variscan belt comprises accreted units of Gondwana, Avalonia and their intervening ocean(s). We compile these datasets in orogenic architecture diagrams, with the aim of objectively assessing the current state of knowledge on the paleogeographic limits and evolution of the Rheic ocean and on the nature and continuity of its suture. Through our preliminary compilation, we identify what data constitutes solid evidence for the existence of the Rheic ocean and whether gaps in the current knowledge exist that have been filled by interpretative work, and discuss tectonic implications and potential paths forward.

Higher serum levels of GPNMB are linked to type 2 diabetes mellitus (T2DM) and metabolic dysfunction-associated steatotic liver disease (MASLD). Disruption of circadian rhythms also influences the development and progression of MASLD. In this study, we investigated how GPNMB modulates hepatic glycogen metabolism and its potential interaction with the hepatic circadian clock. Male DBA/2 J mice, either wild-type (GP+) or carrying an inactivating Gpnmb mutation (GP-), were fed a high-fat diet (48.4% fat) supplemented with 30% fructose in drinking water for 12 weeks. Despite similar weight gain, GP- mice displayed greater global fat mass accumulation and elevated serum triglyceride and cholesterol levels. Surprisingly, GP- mice showed improved glucose tolerance, whereas GP+ mice developed impaired glycemic control. Indirect calorimetry under thermoneutral conditions (30°C) revealed loss of diurnal rhythmicity in energy expenditure (EE) in GP- mice, which was independent of food intake. Despite its preserved rhythms, hepatic clock gene expression in GP- mice showed increased MESOR (e.g., Per1, Per2, and Nr1d1) and increased amplitude (e.g., Nr1d1), indicating higher expression levels throughout the day. GPNMB deficiency further impaired hepatic glycogen storage dynamics, which was attributed to reduced AKT phosphorylation (indicative of defective insulin signaling), reduced FOXO1 phosphorylation, and increased PEPCK-M. Translating our findings to human MASLD patients, GPNMB expression obtained from liver biopsies showed a clear increase across MASLD progression. Importantly, patients with metabolic dysfunction-associated steatohepatitis (MASH) and diabetes who received anti-diabetic treatment showed a reduction in hepatic GPNMB expression. Collectively, our findings suggest that GPNMB plays a role in metabolic adaptation to obesogenic diets, as a Gpnmb loss-of-function model reveals an association with impaired hepatic insulin signaling and glycogen metabolism despite improved systemic glucose tolerance in mice, whereas hepatic GPNMB upregulation correlates with MASLD progression in humans.

Abstract The interannual variability of tropical Atlantic cyclones (TCs) has been linked to ENSO and the Atlantic Meridional Mode. Recent studies have also highlighted the role of the equatorial Atlantic in influencing Cape Verde TCs. However, the stationarity of these teleconnections has not yet been thoroughly examined. In this work, running correlations between the anomalous frequency of TCs originating in the Cape Verde region and tropical sea surface temperatures (SSTs), reveal a shift in recent decades. Although the overall frequency of Atlantic TCs has increased since the 2000’s, changes in atmospheric and oceanic background conditions have weakened the influence of SSTs on Cape Verde TCs. Furthermore, our assessment of eddy kinetic energy as an indicator of African easterly wave activity suggests that, in the context of global warming, the predictive power of sea surface temperatures may be diminished.

Abstract. The Antarctic Ice Sheet is expected to be the dominant contributor to sea-level rise in the coming centuries. However, this contribution is deeply uncertain due to the lack of understanding of some fundamental processes influencing ice-sheet dynamics. A key question is the extent to which submarine melting takes place at the transition between grounded and floating ice. Traditionally, in continental-scale ice-sheet modelling, this area has been treated as an abrupt transition or grounding line with suppressed or strongly limited submarine melting upstream. However, several lines of evidence challenge this view. In many places, changes in ocean tides lead to back and forth migrations of the grounding line over a broad grounding zone and can cause intrusion of warm ocean waters several kilometres upstream of the grounding line, allowing for submarine melting there. Here, we propose a simple parameterization to represent the effect of tidally-controlled migrations of the grounding line and tidal-water intrusion in submarine melting in continental-scale ice-sheet models. We calibrate the magnitude of the parameter controlling the extent of oceanic water intrusions against the observational evidence as inferred from differential interferometry synthetic aperture radar. We use a three-dimensional ice-sheet model to investigate the impact of this parameterization on Antarctic ice-sheet projections under a high-emission climate scenario extending to the year 3000. Our results show that increasing the extent of tidal intrusion, reinforced by dynamic feedbacks, leads to stronger and more widespread grounding-zone retreat under warming scenarios, and consequently ice-stream acceleration, ice-shelf thinning and debuttressing. This implies larger sea-level contributions compared to the usual treatment of melt at the grounding line and should be accounted for in future projections.