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The Lower Cretaceous in the Paraná Basin record a large volcanic event (Serra Geral Formation) that covered an active sedimentary system (Botucatu Formation), before the fragmentation of the southern Gondwana. Therefore, the fluvial-aeolian deposits underlying aeolian deposits of residual dunes, were gradually covered by volcanic flows. Intense basic and minor acidic magmatism covered an extensive continental aeolian environment. The interface between the two units shows an aeolian environment during the early stages of volcanism forming deposits and volcano-sedimentary features overlying and underlying the flows. In six outcrops on the southern portion of the current border of Paraná Basin, in Rio Grande do Sul state, these deposits and features were recognized, showing the complexity of the environment and the processes associated with lava flows and sediments. They were formed by the interaction of consolidated or unconsolidated sediments, saturated or not in the water, with basaltic or dacitic flows. Interaction features and deposits synchronous to volcanism (volcanoclastic), later or in intervals between volcanic events (epiclastic) and only cover, with absence of interactions, were identified. Through the distinctive characteristics of the interaction processes between the volcanic rocks and the sediments analyzed in the volcanic-sedimentary features and deposits, the morphology of the aeolian environment of Botucatu Formation could be, by analogy, compared to the current aeolian environments. The proposed paleoenvironment indicates a sedimentary environment with different domains, categorized by their water saturation. The different siliciclastic components found in each domain allowed the generation of different features and volcanic-sedimentary deposits evidencing aspects related to the presence or absence of water among the proposed domains. • Deposits and features of volcano-sedimentary interaction for the Upper Jurassic - Lower Cretaceous. • Mechanisms that influence the processes of igneous and sedimentary perspectives. • Water contribution or humidity for paleoenvironmental models in Cretaceous of Paraná Basin. • Distinctive characteristics of interaction processes between the volcanic rocks and siliciclastic sediments. [ABSTRACT FROM AUTHOR]

The 12 August 2021 eruption of Fukutoku-Oka-no-Ba, a shallow submarine volcano in the Izu-Bonin arc of Japan, is one of few documented submarine eruptions to make a large aerial plume and floating pumice raft. Relative to past eruptions, this event was well-covered by multiple high resolution satellite remote sensors, raising the possibility of resolving important questions about the timing of raft and plume formation, and their relationship. Here we use satellite remote sensing to assess the eruption timeline, style, rates, and products. We use the Himawari-8 satellite to assess the plume volume flux and height through time. In addition, we use a combination of ultra-high resolution satellite imagery to assess the timing and mechanisms of raft formation. We find that the 16 km eruption plume was ice-rich and conclude that the 0.1 km3 raft and eruption plume were co-genetic. Finally, we suggest that pumice clasts were delivered to the raft by tephra jets, ballistics, and near-vent fallout from the plume. Together our observations reveal that the fallout of pumice lapilli from a water-rich eruption column generated a large pumice raft. • A 0.1 km3 pumice raft and 16 km volcanic plume formed at the same time. • Tephra jets, ballistics, and near-vent clast fallout fed the raft. • Decoupling of clasts from the plume resulted in a water-rich and lapilli-poor plume. • Ultra-high resolution imagery reveal fine-scale features in the pumice raft. [ABSTRACT FROM AUTHOR]

Arsenic contamination of groundwater in the Southern Gulf Coast Aquifer of Texas is a critical public health concern as much of the area is rural in nature with decentralized water supplies. Previous studies have pointed to volcanic deposits as the regional source of arsenic but no definitive or reliable predictors of arsenic maximum contaminant level (MCL) exceedance have been identified. In this study, we have studied the effect of various hydrogeochemical parameters as well as soil and land-use variables on arsenic MCL exceedance using logistic regression (LR) techniques. The LR models display good accuracy of 75% or higher but suffer from a high rate of false negatives, highlighting the challenges in capturing the spatial irregularities of arsenic in this region. Despite not displaying high statistical significance, pH appears to be an important variable in the LR models—its effect on arsenic exceedance is not clear and warrants further investigation. The results of the study also show that groundwater vanadium and fluoride are consistently the only significant variables in the models developed; the positive coefficients for both these elements indicates a common geogenic source for arsenic, fluoride and vanadium, corroborating the findings of earlier studies.

The stone artefacts from Sirmium, held at the Museum of Srem, were sampled and analyzed in order to establish an archaeological database connected with Roman quarries and possible transport routes along the Sava and Danube Rivers. Of the artefacts made of Neogene limestone three lithotypes were identified. Two of them were determined as originating from the known Roman quarry in the Drina Valley (NE Bosnia). For the third lithotype and its subtypes a model of the hypothetical quarry is proposed, the location of which is suggested to be outside the Drina river basin. Beside limestone, the sampled artefacts also revealed two types of porous volcanoclastic rocks of andesitic composition, which supposedly originate from two different microlocations in the Drina river basin.

Arsenic contamination of groundwater in the Southern Gulf Coast Aquifer of Texas is a critical public health concern as much of the area is rural in nature with decentralized water supplies. Previous studies have pointed to volcanic deposits as the regional source of arsenic but no definitive or reliable predictors of arsenic maximum contaminant level (MCL) exceedance have been identified. In this study, we have studied the effect of various hydrogeochemical parameters as well as soil and land-use variables on arsenic MCL exceedance using logistic regression (LR) techniques. The LR models display good accuracy of 75% or higher but suffer from a high rate of false negatives, highlighting the challenges in capturing the spatial irregularities of arsenic in this region. Despite not displaying high statistical significance, pH appears to be an important variable in the LR models—its effect on arsenic exceedance is not clear and warrants further investigation. The results of the study also show that groundwater vanadium and fluoride are consistently the only significant variables in the models developed; the positive coefficients for both these elements indicates a common geogenic source for arsenic, fluoride and vanadium, corroborating the findings of earlier studies. [ABSTRACT FROM AUTHOR]

We explored the predictive value of common landscape characteristicsfor landslide vegetative stages in the Luquillo Experimental Forest of Puerto Rico using four different analyses. Maximum likelihood logistic regression showed that aspect, age, and substrate type could be used to predict vegetative structural stage. In addition it showed that the structural complexity of the vegetation was greater in landslides (1) facing the southeast (away from the dominant wind direction of recent hurricanes), (2) that were older, and (3) that had volcaniclastic rather than dioritic substrate. Multiple regression indicated that both elevation and age could be used to predict the current vegetation, and that vegetation complexity was greater both at lower elevation and in older landslides. Pearson product-moment correlation coefficients showed that (1) the presence of volcaniclastic substrate in landslides was negatively correlated with aspect, age, and elevation,(2) that road association and age were positively correlated, and (3) that slope was negatively correlated with area. Finally, principal components analysis showed that landslides were differentiated on axes defined primarily by age, aspect class, and elevation in the positive direction, and by volcaniclastic substrate in the negative direction. Because several statistical techniques indicated that age, aspect, elevation, and substrate were important in determining vegetation complexity on landslides, we conclude that landslide succession is influenced by variation in these landscape traits. In particular, we would expect to find more successional development on landslides which are older, face away from hurricane winds, are at lower elevation, andare on volcaniclastic substrate. Finally, our results lead into a hierarchical conceptual model of succession on landscapes where the biota respond first to either gradients or disturbance depending on their relative severity, and then to more local biotic mechanisms such asdis [ABSTRACT FROM AUTHOR]