Ambient seismic noise has gained extensive applications in seismology and plays a pivotal role in environmental seismic studies. This study focuses on the Río de la Plata Coastal Plain, employing the horizontal-to-vertical spectral ratio (HVSR) method on ambient seismic noise records to analyze subsurface dynamics. The region’s hydrogeology is complex, featuring partially interconnected coastal aquifers. The HVSR analysis reveals two peaks, with P₀ associated with the sediment-basement interface and P₁ linked to a shallower stratigraphic discontinuity. Temporal analysis of P₁ highlights cyclical patterns correlated with estuarine levels, suggesting a relationship between variations in seismic velocities and tidal dynamics. Comparisons with aquifer data support the hypothesis that tidal variations influence subsurface mechanical properties, impacting the HVSR function. The study hints at the potential of ambient seismic noise analysis as a non-invasive and cost-effective method for studying coastal aquifers and understanding groundwater dynamics. Ongoing research aims to further explore these relationships for enhanced groundwater resource management.

The Maltese archipelago is renowned for its spectacular coasts, characterized by vertical cliffs and scree slopes. In the western sector of Malta and the eastern region of Gozo, a marly clay formation with ductile properties underlying a stiff limestone unit has led to relevant lateral spreading. Utilizing drone aerial photogrammetry, digital elevation models, and satellite imagery, we analyzed the ongoing geomorphological processes across five promontories, selected as case studies. Our analysis reveals a complex interaction between geological structures, Quaternary sea level fluctuations, and lateral spreading processes. Photogrammetric models show that once detached, blocks from the plateaus tend to topple and fall or experience subsidence and backtilting. At Rdum il-Qammieħ, fractures up to 250 m long and openings of up to 2 m were observed, while at Sopu, detached blocks exhibit subsidence of up to 50% and rotations nearing 60°. In all the studied promontories, rotational slides predominantly occur at the frontal sectors, while toppling mechanisms are more common along scarp-edged plateaus. The thickness ratio between the stiff and the ductile formation, ranging from 0.13 to 1.12, along with slope gradients between 10° and 41°, further influence the stability of these coastal features. We discuss the structural and sea level influences on Maltese coastal cliff development over the last 125 ky. We propose a conceptual model outlining the evolution of the Malta Graben promontories through a three-stage evolutionary model: proto-promontories, cliff demolition, and isolation. This model emphasizes the significant role of predisposing, preparatory, and triggering factors in the geomorphological evolution of the Maltese coastline. Our findings provide essential insights into the landscape changes in the Maltese archipelago and represent a useful tool for coastal management and hazard mitigation strategies.

Web site of the journal of the Argentinian Association of Paleontology

From the analysis of the taphonomic attributes of the specimens of Heleobia parchappii found in fluvial and paleolacustrine sequences of the lower basin of the Salado River, the surface alteration of their shells was comparatively studied in order to assess the differences between both environments. The main results that were obtained by means of Non-Metric Multidimensional Scaling (NMDS) and analysis of similarity (ANOSIM) tests (R=0.31, p<0.01) enabled the recognition and statistical differentiation of both groups of samples. The taphonomic characteristics presented by those that were recovered from the paleolacustrine environment are more similar to each other, whereas those from the fluvial environment showed greater dispersion. Through the similarity percentage (SIMPER) analysis we could determine that the variables of discoloration and dissolution were the most important features to differentiate both groups, and that the values of the indexes (Total Taphonomic Grades) were always higher in the paleolacustrine assemblages, thus showing greater decay. The differences of preservation could be explained by the residence time of the remains near the water-sediment interface as well as by the differences in the sedimentation rate in both environments, which control the different exposure cycles of the shells. These differences would be related to changes in the hydrological regime (fluctuations in surface and groundwater levels) that, although affecting the entire study area, are more intense and frequent in shallow lakes, therefore favoring the decay of the shells accumulated in this environment.

Con la finalidad de contribuir al conocimiento de la evolución paleoambiental y paleoclimática ocurrida desde el Pleistoceno Tardío hasta el Holoceno Tardío en la Pampa Ondulada, noreste de la provincia de Buenos Aires, se presentan los resultados obtenidos en las investigaciones interdisciplinarias efectuadas en la cuenca hídrica Salto-Arrecifes. Estos resultados, se integran con los publicados por los autores de este trabajo referentes a las características geológicas y paleoecológicas que dominaron desde el Pleistoceno Tardío en la región pampeana. Se acotan temporalmente las sucesiones sedimentarias de 10 localidades de la cuenca Salto-Arrecifes y se asocian a las descriptas para las cuencas de los ríos Luján y Areco. Se definen cuatro unidades depositacionales que caracterizan los procesos sedimentarios ocurridos en los valles actuales de las cuencas media-inferior de estos cursos. Se discriminan las diversas facies sedimentarias presentes en los sectores continentales y en las secciones cercanas a la desembocadura. La sedimentación pleistocena tardía–holocena, ocurrida en la cuenca media de los ríos Salto-Arrecifes, Luján y Areco, muestra la incidencia de los cambios climáticos acaecidos durante el lapso. En tanto, en las facies reconocidas en los tramos cercanos a la desembocadura de ellos, se suma la incidencia de los cambios eustáticos producidos durante el interglacial actual. La exposición en las barrancas de depósitos que poseen las mayores edades registradas y que ocurre en forma saltuaria a lo largo del valle actual, podría indicar que la neotectónica ha sido otro factor extrínseco actuante en las cuencas en algún momento del Holoceno Tardío.