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Melts with rhyolite compositions originate from partial melting of crustal rocks or extensive differentiation of basaltic melts, at temperatures in the range of 800 °C. Accordingly, they are confined to the shallow continental crust. Nevertheless, experimental studies have demonstrated that dacite-rhyolite melts can be generated at higher temperature (> 1000°c) and pressure (>2 GPa), by partial melting of continental crustal lithotypes, but direct evidence for their occurrence has never been found. This implies that rhyolite melts may be produced at mantle conditions either by subduction of sedimentary material or exhumation of subducted continental crust.Ephemeral rhyolite melt inclusions were found preserved in peridotite xenoliths from Tallante (Betic Cordillera, southern Spain) that are remnants of a supra-subduction mantle wedge. Here, the interaction of silica-rich melts with peridotite generated hybrid mantle domains, characterized by the occurrence of millimetre-sizes felsic veins with crust-like Sr-Nd-Pb-O- isotope compositions. The “Tallante” composite xenoliths were found among a wide population of peridotitic xenoliths, and display extreme compositional and isotopic heterogeneities both within the ambient peridotite and within the felsic veins. The latter consist of orthopyroxene, plagioclase, and quartz, and they are separated from the surrounding peridotite by an orthopyroxene-rich reaction zone. In their mineral phases, rhyolite glass inclusions and interstitial films associated to quartz crystals were observed. Petrological evidence and thermodynamic modelling indicate that rhyolite melts were originated by partial melting of near an-hydrous garnet-bearing metapelites at temperatures above 1000 °C. Partial melting was likely triggered by near-isothermal decompression during rapid exhumation of previously subducted crustal slivers. The melts reacted with the ambient lithospheric mantle at lower temperature (900 °C) and produced orthopyroxene, followed by plagioclase, quartz, and phlogopite. On the basis of chemical characteristics, it is hypothesized that potassic (HK-calc-alkalic to shoshonitic) and ultrapotassic magmas may originate from metasomatic mantle sources generated from the interaction of crustal rhyolitic melts with mantle peridotite.

Most orogenic belts are close to convergent plate margins. However, some orogens are formed far away from plate boundaries, as a result of compressional stress propagating within plates, basal loading, or a combination of thereof. We focus on the Atlas of Morocco, which is such an intraplate orogeny and shows evidence of mantle driven uplift, and plume-related volcanism. How these processes interact each other is still poorly constrained and it provides clues about intraplate stress propagation, strain localization, and lithospheric weakening due to mantle dynamics. We present three sets of observations constructed by integrating previous data with new analyses. Crustal and thermal evolution constraints are combined with new analyses of topographic evolution and petrological and geochemical data from the Anti-Atlas volcanic fields. Our findings reveal that: i) crustal deformation and exhumation started during middle/late Miocene, contemporaneous with the onset of volcanism; ii) volcanism has an anorogenic signature with a deep source; iii) a dynamic deep mantle source supports the high topography. Lastly, we conducted simple numerical tests to investigate the connections between mantle dynamics and crustal deformation. This leads us to propose a model where mantle upwelling and related volcanism weaken the lithosphere and favor the localization of crustal shortening along pre-existing structures due to plate convergence.

The effects of peat burning on organic‐rich agricultural soils of the Mezzano Lowland (NE Italy) were evaluated on soil profiles variously affected by smoldering. Profiles were investigated for pH, electrical conductivity, bulk density, elemental and isotopic composition of distinct carbon (and nitrogen) fractions. The results suggest that the horizons affected by carbon loss lie at depths 10–70 cm, where the highest temperatures are developed. We suggest that the exothermal oxidation of methane (mediated by biological activity) plays a significant role in the triggering mechanism. In the interested soils we estimated a potential loss of Soil Organic Carbon of approximately 110 kg m −2 within the first meter, corresponding to 580 kg CO2 m −3. The released greenhouse gas is coupled with a loss of soil structure and nutrients. Moreover, the process plausibly triggers mobility of metals bound in organometallic complexes. All these consequences negatively affect the environment, the agricultural activities and possibly also health of the local people., Key Points Peat burning in the Mezzano Lowland is a process active since wetland reclamation and variously affects the soil structure and carbon contentThe main carbon loss occurs in the depth interval 10–70 cm, where temperature up to 750°C is recordedThe process induces negative effects to surrounding environment, agriculture activities and possibly also human health

The F'Kirina plain in eastern Algeria is an endorheic basin suffering water scarcity due to a combination of natural and man-made causes. Its hydrogeological system is complex as made by interconnected aquifers represented by Mesozoic, Cenozoic, and Quaternary lithological units. The combination of drought indicators and water level data shows that a groundwater drought affected the plain during the last 15 years, which reflects on current water quality. The reported geochemical analyses, including major ions and trace elements, indicate that the groundwater resource is suffering from salinization, mainly due to evaporation and leaching of soil salts, a process that is coupled with simultaneous cation-exchange effects. In this framework, we observe a geochemical evolution from the fresh Ca–HCO3 facies, typical of springs bordering the plain, towards more saline groundwater characterized by chloride/sulphate-rich facies in the middle of the plain approaching the sebka. However, geochemical diagrams indicate that in few wells salinization is also influenced by upraising of deep groundwater. The water isotopic composition of the F'Kirina plain samples suggests that they diversely record both recharge and evaporation components. Moreover, the most 18O and D depleted compositions among the investigated ground-waters suggest recharge contributions by comparatively higher elevation or the involvement of old (fossil) water components.

Industrial farming without considering soil biological features could lead to soil degradation. We aimed to evaluate the biochemical properties (BPs) and biological fertility (BF) of different soils under processing tomato cultivation, estimate the BF through the calculation of a simplified BF index (BFIs), determine if the crop was affected by BP and BF. Three farms were individuated in Modena (MO), Ferrara (MEZ) and Ravenna (RA) provinces, Italy. Soil analysis included total and labile organic C, microbial biomass-C (Cmic) and microbial respiration measurements. The metabolic (qCO2), mineralization (qM) and microbial (qMIC) quotients, and BFIs were calculated. Furthermore, plant nutrient contents were determined. The low Cmic content and qMIC, and high qCO2 found in MEZ soils indicate the occurrence of stressful conditions. The high qMIC and qM, and the low qCO2 demonstrated an efficient organic carbon incorporation as Cmic in MO soils. In RA soils, the low total and labile organic C contents limited the Cmic and microbial respiration. Therefore, as confirmed by the BFIs, while MO showed the healthiest soils, RA soils had an inefficient ecophysiological energy state. However, no effects on plant nutrient contents were observed, likely because of masked by fertigation. Finally, BP monitoring is needed in order to avoid soil degradation and, in turn, crop production decline.

The overburning test method was developed to simulate and predict lime densification, agglomeration, and sporadic melting at the highest potential temperature of lime kilns. These events, that belong to the so-called “sticking tendency” phenomenon, are associated to formation of crusts, occlusions, and blockages in vertical lime kilns. In this work, fifty carbonate rocks, their insoluble residues, and derived burnt products were investigated through a multianalytical approach. Four groups of rocks having different burnability were identified. In addition, three fundamental mechanisms were related to the above-mentioned phenomena: dehydration melting, solid-state, and liquid-phase sintering processes. Guidelines for raw materials suitability were outlined for designing new kilns and to check the quality control in already active plants.

This work reports an ab initio study on the carbon (C), nitrogen (N), and sulphur (S) elemental and isotope compositions of the Padanian Plain sediments collected in the province of Ferrara (Northern Italy). The investigated sediments were already characterized by previous research that highlighted a bimodal provenance, as some sediments are from the Alpine chain and were conveyed to the plain by Po River, whereas others are from the Apennine chain and were conveyed to the plain by the Reno River. This information was obtained considering the concentration of heavy metals retrieved from hundreds of X-ray fluorescence analyses available in the literature, whereas CNS elemental and isotope compositions are unknown. These tracers are generally considered scarcely useful to identify the sediment provenance, as influenced by multiple environmental factors. However, this work challenges these assertions observing that 13C/12C, 15N/14N, 34S/32S are significantly different in Po and Reno River sediments. Our hypothesis is that the CNS geochemical signal is 1) mainly regulated by the organic fraction included in the alluvial sediments, and 2) these organic fraction have in turn a specific composition in the distinct source catchments. More in general, the presented data increase the knowledge on the local elemental and isotopic backgrounds. This is important because many pollutants contain significant CNS concentration and specific isotope composition. Therefore, they serve as baseline and will provide new tools to recognize possible anthropogenic anomalies in the studied area.

Carbon and nitrogen elemental (C-N, wt%) and isotopic ( δ 13 C- δ 15 N, ‰) investigation has been carried out on alluvial and deltaic soils from the Padanian plain (northern Italy), an area interested by intensive agricultural activities, to refine previous inferences on depositional facies, pedogenetic processes and anthropogenic influences. Soil analysis, carried out by EA-IRMS, have been focused on inorganic and organic fractions properly speciated by a thermally-based method, whereas further insights on the organic matter constituents have been obtained by sequential fractionation. The bulk EA-IRMS analyses reveal a remarkable compositional heterogeneity of the investigated soils (TC 0.89 to 11.93 wt%, TN 0.01 to 0.78 wt%, δ 13 C TC -1.2 to -28.2‰, δ 15 N -1.2 to 10.0‰) that has to be explained as an integration between inorganic and organic pools. The latter have been subdivided in Non-Extractable Organic Matter (NEOM, δ 13 C -16.3 to -28.6‰) and in extractable fractions as Fulvic (FA, δ 13 C -24.7 to -27.5‰, δ 15 N 0.6 to 5.7‰) and Humic (HA, δ 13 C -24.6 to -27.0‰, δ 15 N 1.0 to 9.7‰) Acids, which have been used to infer soil dynamics and Soil Organic Matter (SOM) stability processes. Results indicate that SOM at depth of 100 cm was generally affected by microbial reworking, with the exception of clayey and peaty deposits in which biological activity seems inhibited. Peaty and clayey soils display an organic fraction loss of ca. 20% toward the surface, suggesting deterioration possibly induced by intensive agricultural activities. These latter may be the cause of the ubiquitous losses of organic fraction throughout the investigated area over the last seventy years, evaluated by the comparison with historical data on corresponding topsoils. The obtained insights are very important because these soils are carbon (and nitrogen) sinks that are vulnerable and can be degraded, loosing agricultural productivity and potentially contributing to greenhouse gases fluxes.

A new analytical approach (Thermally Based Separation, TBS) for the characterisation of inorganic (IC) and organic (OC) carbon pools in alluvial soils has been tested. The method does not involve any chemical pre-treatment of samples and relies on different thermal stabilities of IC and OC pools, which can be accurately determined with an EA-IRMS analytical system. Elemental (C, g/kg) and isotopic (δ13C, ‰) carbon data were used to check the reliability of the TBS method by calculating the mass balances using the measured IC and OC fractions and total carbon (TC). TBS was applied to 7 soil samples from the Padanian alluvial plain (NE Italy) that were collected from different depths and characterised by textural/geochemical heterogeneity. The method allowed for a mean carbon elemental recovery of 99% (SD = 2%), and mean isotopic deviation (Δ13C) between theoretical (δ13COC XOC + δ13CIC XIC)/(XOC + XIC) and measured δ13CTC of 0.2‰ (SD = 0.3‰). A comparison of TBS with other conventional methods for carbon separation provided insights into the possible effects of sample acidification on the soil organic pools. The results suggest a higher robustness of TBS compared to conventional methods in the determination of organic and inorganic carbon pools in soils. This is because TBS bypasses any possible fractionation derived from the hydrolysis of soil organic matter and therefore accurately determines the carbon isotopic composition of the OC and IC fractions. TBS appears to be more robust than conventional methods and is independent from the IC/OC ratio of the samples, from the unpredictable complexity of soil organic matter and from the arbitrary application of the acidification routine. On this basis, TBS represents a very promising approach for a correct and complete characterisation of soil carbon pools.

The Sacca di Goro and Sacca di Scardovari are two coastal lagoons of the Po River delta facing the northern Adriatic Sea. They are sensitive ecosystems both from the naturalistic and socio-economic point of view, since they are included in a natural park and are high productivity shellfish sites. Bottom sediments from the two lagoons have been analysed for their textural and geochemical (major and trace elements by XRF) composition in order to identify natural backgrounds and anthropogenic inputs. OC, N and δ13COC data have been also carried out by EA-IRMS to highlight the association of heavy metals with inorganic or organic sedimentary components. Results show that abundances of siderophile (Cr, Ni, Co) heavy metals in samples from the two lagoons are generally in the range of those recorded in alluvial sediments from the neighbours and are associated with the finest (clayey) fraction. Among chalcophile heavy metals, Pb and Zn display significant enrichments relative to the local geochemical backgrounds suggesting anthropogenic sources. They appear to be preferentially associated with the sedimentary organic matter that, according to the isotopic composition, is mainly formed by the incorporation of different proportions of macroalgae and macrophytes that have a significant bioaccumulation capacity. Taking into consideration that the extent of the algal biomass is sensitive to anthropogenic pressure and climatic changes, the trace element budget of sediments from these lagoons has to be monitored in the future, also to assess the impact of heavy metals on shellfish production.

In this paper we present an elemental and isotopic investigation of carbon and nitrogen in the soil-plant system. Plants grown in an unamended soil were compared to plants grown in a soil amended with natural and NH4+-enriched zeolitites. The aim was to verify that zeolitites at natural state increase the chemical fertilization efficiency and the nitrogen transfer from NH4+-enriched zeolitites to plants. Results showed that plants grown on plots amended with zeolitites have generally a δ15N approaching that of chemical fertilizers, suggesting an enhanced nitrogen uptake from this specific N source with respect to the unamended plot. The δ15N of plants grown on NH4+-enriched zeolitites was strongly influenced by pig-slurry δ15N (employed for the enrichment process), confirming the nitrogen transfer from zeolitites to plants. The different agricultural practices are also reflected in the plant physiology as recorded by the carbon discrimination factor, which generally increases in plots amended with natural zeolitites, indicating better water/nutrient conditions.

The agricultural European Innovation Partnership (EIP-AGRI) Focus Group on Soil Organic Matter (SOM) content in Mediterranean regions highlighted the poor organic carbon (OC) content in the investigated soils, with some areas, especially in Southern Europe, showing low (≤2%) or even very low (≤1%) OC values. For this reason Emilia-Romagna Region (Northeastern Italy) invested heavily in the Rural Development Programme (RDP), which financed projects addressed to the needs of specific geographical areas. Among these, SaveSOC2 project (Save Soil Organic Carbon) aims to evaluate the quantity and quality of SOM in both conventional and organic farms from distinct pedo-climatic setting of Emilia-Romagna Region and with possible critical issues, in order to identify the best agricultural practices which could contribute to i) carbon conservation and sequestration in soil and ii) mitigation of SOM mineralization responsible for the greenhouses emissions. Here we report the data of the “Tassinari” organic farm located at Bondeno, near Ferrara city in Padania Plain, an area characterized by soil with very low amount of OC. In the selected organic farm, topsoil samples (0-15 cm and 15-30 cm depth) were collected from strawberry fields and orchards converted from conventional to organic production since 1992. The soils have loam and silt loam texture, they are subalkaline (pH: 7.9-8.7) and nonsaline (EC: 0.1-0.2 dS m-1). To characterize the soil inorganic (SIC) and organic (SOC) carbon, for each sample, elemental and isotopic analyses were performed using the Thermally Based Separation protocol tested by Natali et al. (2018) with an EA-IRMS. As expected, the vertical distribution of carbon along each site showed a negative correlation between SIC and SOC contents, as IC slightly increase over depth while OC show a clear decline. Moreover, irrespectively of the sampling depth, the OC values (0.90-1.14 wt.%) are always lower than those of IC (1.04-2.50 wt.%). The relatively low negative δ13C values of the total carbon (from -12.1‰ to -9.0‰) reflect the predominance of SIC in the investigated topsoils. The low storage of organic matter in this area is also confirmed by the OC stock value in the topsoils, which is on average 42.6 Mg/ha. A Soli TOC Cube® was also used to discriminate the labile organic carbon (TOC400) and the residual oxidizable carbon (ROC) fractions, which are oxidized at temperature below and above 400°C, respectively. In all the investigated topsoils, the TOC400 values (0.60-0.84 wt.%) are higher than those of ROC (0.21-0.28 wt.%), indicating large amount of “fresh” organic matter, and low amount of residual organic carbon. The high relative presence of labile OC pools, probably due to the soil fertilisation with easy available organic compounds, can be critical for SOM sequestration, preventing the accumulation of stabilised organic compounds. Natali C., Bianchini G., Vittori Antisari L. 2018. Thermal separation coupled with elemental and isotopic analysis: A method for soil carbon characterisation. Catena 164, 150-157.

The exploitation of soils due to farming has produced a progressive loss of soil organic matter (SOM) over the years. At the same time, the degradation of SOM has led to a decline of several ecosystem services provided by soil, especially in mountain. Against this background, the partnership between Department of Physics and Earth Sciences of University of Ferrara and Department of Agricultural and Food Sciences of University of Bologna led to the creation of the SaveSOC2 project (Save Soil Organic Carbon), funded by Rural Development Programme of Emilia-Romagna Region. This project primarily seeks to investigate and promote carbon storage processes in agricultural soils of Emilia-Romagna Region (NE Italy). The present study outlines an overview about the SOM dynamics of “I Rodi” organic farm, located in the Modena Apennine. “I Rodi” produces and processes small organic fruits, especially raspberries. Three different sites (grassland -G, very low productive raspberries -LR, and good productive raspberries -GR) have been selected and the topsoils (0-15 cm and 15-30 cm) have been investigated. Elemental and isotopic analyses of soil C were performed using an EA-IRMS. In particular, the application of the Thermally Based Separation protocol [1] allowed the determination of both inorganic (IC) and organic (OC) carbon contents in each soil sample. OC accounted for 93.50% of the total carbon (1.72-4.84 wt.%). The negative δ13C values of the total carbon (from -27.8 to -19.7 ‰) confirmed the predominance of OC over IC in the investigated soils. The average values of OC isotopic C signature showed a decreasing trend among the three sites (-28.2, -27.2 and -25.8‰ for GR, G and LR, respectively), with the low productivity site having the highest δ13C value. The isotopic C signature of separated organic C fractions (0-15 cm topsoils) showed that humin (832-879 g/kg), which is the SOM fraction mostly interacting with the soil mineral phase and the largest pool, confirmed the observed trend (-27.5, -27.0, -26.4‰, GR, G and LR). The humic acids (6-17 g/kg) showed similar trend but lower δ13C values in all sites (-28.5, -28.0, -26.8 ‰, GR, G and LR). Finally, fulvic acids (5-10 g/kg) differed, having dissimilar trend and values of δ13C (-27.1, -26.8, -26.0 ‰ for G, GR and LR). Comparing to G, the GR data suggested that organic management i) did not decrease quantity and quality of organic matter, and ii) it was more efficient in OC stabilisation, increasing the amount of less transformed OC in both humin and humic acids (more negative δ13C values). In the LR site, instead, the observed trend can be due to low suitability of this soil to raspberries production, negatively affecting both crop yields and organic C dynamics. In our opinion, in order to combine agricultural productivity and its sustainability, more attention should be paid both to soil management and suitability in the area.[1] Natali C., Bianchini G., Vittori Antisari L. 2018. Thermal separation coupled with elemental and isotopic analysis: A method for soil carbon characterisation. Catena 164, 150-157.

The water composition of the river Adige displays a Ca&ndash, HCO3 hydrochemical facies, mainly due to rock weathering. Nitrate is the only component that has increased in relation to growing anthropogenic inputs. The aim of this paper was to identify the origin of the dissolved components in this river and to establish the relationship between these components and critical zone processes within an evolving framework where climatic and human impacts are influencing the riverine system. In particular, emphasis is given to a wide spectrum of isotope data (&delta, 18O, &delta, 2H, &delta, 13C, &delta, 15N, &delta, 34S, 87Sr/86Sr, &delta, 11B), which is considered useful for determining water origin as well as natural and anthropogenic impacts on riverine geochemistry. Together with oxygen and hydrogen isotopes, which are strictly related to the climatic conditions (precipitation, temperature, humidity), the carbon, sulphur, strontium and boron signatures can describe the magnitude of rock weathering, which is in turn linked to the climatic parameters. &delta, 13CDIC varies regularly along the riverine profile between &minus, 4.5&permil, and &minus, 9.5&permil, and &delta, 34SSO4 varies regularly between +4.4&permil, and +11.4&permil, On the other hand, &delta, 15NNO3 shows a more scattered distribution between +3.9&permil, and +10.5&permil, with sharp variations along the riverine profile. 87Sr/86Sr varies between 0.72797 in the upper part of the catchment and 0.71068 in the lower part. &delta, 11B also shows a rough trend, with values approaching 7.6&permil, in the upper part and 8.5&permil, in the lower part. In our view, the comparatively low &delta, 34S, &delta, 11B, and high 87Sr/86Sr values, could be a proxy for increasing silicate weathering, which is a process that is sensitive to increases in temperature.

In the Main Ethiopian Rift (MER) area, rural populations often use water that exceeds the World Health Organization thresholds for fluoride (F&ndash, ) and arsenic (As), two elements that are hazardous for human health. In this study, twenty-nine water samples were collected from lakes and hot and cold springs in southern MER to investigate source(s) and health-risk of the F&ndash, and As contamination. According to major ion and trace element analyses, only cold spring water is safe for consumption, whereas hot spring water is the most contaminated. Leaching tests performed with the MER rhyolitic volcanic rocks and their weathered products (fluvio-lacustrine sediments) demonstrate that the main cause of the F&ndash, and As release is geogenic, i.e., not related to anthropogenic activities. The weathering of volcanic glass and minerals (apatites, clays, hydro-oxides) by CO2-bearing alkaline water induces the mobilisation of F&ndash, and As from solid to liquid phase. This process is particularly fast, when fluvio-lacustrine sediments are involved, and can be further enhanced by hot groundwater leaching. This study, investigating the distribution, sources, and mechanisms of F&ndash, and As release in MER water, could be of interest also for other sectors of the East African Rift and other similar volcano-tectonic settings.

Sustainable agricultural management is needed to promote carbon (C) sequestration in soil, prevent loss of soil fertility, and reduce the release of greenhouse gases. However, the influence of agronomic practices on soil C sequestration depends on the existing pedoclimatic features. We characterized the soils of three farms far away each other in the Emilia-Romagna region (Northern Italy): an organic farm in the Northern Apennines, a biodynamic farm, and a conventional farm on the Po Plain. The total, inorganic, and organic carbon in soil, as well as the distinct humic fractions were investigated, analyzing both the elemental and isotopic (13C/12C) composition. In soils, organic matter appears to be variously affected by mineralization processes induced by microorganisms that consume organic carbon. In particular, organic carbon declined in farms located in the plain (e.g., organic carbon down to 0.75 wt%, carbon stock0-30 cm down to 33 Mg/ha), because of the warmer climate and moderately alkaline environment that enhance soil microbial activity. On the other hand, at the mountain farm, the minimum soil disturbance, the cold climate, and the neutral conditions favored soil C sequestration (organic carbon up to 4.42 wt%, carbon stock0-30 cm up to 160 Mg/ha) in humified organic compounds with long turnover, which can limit greenhouse gas emissions into the atmosphere. This work shows the need for thorough soil investigations, to propose tailored best-practices that can reconcile productivity and soil sustainability.

Construction materials affected by black crusts (BCs) can be subjected to restoration, demolition, recycling or even to their management as waste products. Therefore, the determination of their chemical features should be considered a crucial step before undertaking any action. In this work, we present the development of an analytical methodology useful to be implemented as a routine screening tool to detect recent and past atmospheric emissions of heavy metals, nowadays superficially deposited or even encapsulated in BCs. For its development, BCs together with the underneath original substrate/construction material were sampled from the historical construction Punta Begona Galleries (Getxo, Basque Country, North of Spain). In order to detect quickly and in a cost-effective way the stratification of the metallic deposits in the BCs over time (surface or external/recent and internal/past), thin sections were analyzed by elemental spectroscopic imaging techniques (SEM-EDS and mu-ED-XRF). In the external part of the BCs, iron particles were mainly identified, whereas in the inner areas (past deposition events) of the most exposed BCs to the atmosphere, lead accumulations together with zinc and copper were identified. Additional Raman imaging studies allowed to perform the molecular speciation study of lead, identifying mainly laurionite (PbClOH) together with hydrocerussite (Pb-3(CO3)(2)(OH)(2)). The presence of the mentioned lead chloride hydroxide confirms the role of the marine aerosol (chloride input) in the formation of the metallic compounds. These experimental evidences were used to assist the chemical equilibrium models developed to explain the reactivity pathway, which lead to the formation of the identified compounds. Through ICP-MS and lead isotopic ratio analysis, more than 3000 mg kg(-1) of lead were quantified in the BCs, probably coming from the old emissions conducted by the old power station close to the construction,. That lead content can be high enough to consider those crusts as a source of metallic contamination and a possible risk to the environment and human health. (C) 2019 Elsevier Ltd. All rights reserved.

The quantification of soil carbon pools is a pressing topic both for the agriculture productivity and to evaluate the Greenhouse Gases (GHG) sequestration potential, therefore a rapid and precise analytical protocol for carbon speciation is needed. Temperature-dependent differentiation of soil carbon in compliance with the DIN (German Institute for Standardization) 19539 standard has been applied for the first time on 24 agricultural soil samples from the Po River Plain (Italy), with the aim of investigate their thermal behavior in the 50−900 °C interval. The results invariably show the existence of three soil carbon pools having different thermal stabilities, namely, thermally labile organic carbon (TOC400), residual oxidizable carbon (ROC) and total inorganic carbon (TIC900), in the intervals of 300−400 °C, 510−600 °C and 700−900 °C, respectively. Significant relationships have been observed between the above mentioned organic and inorganic carbon pools and the associated isotopic composition: 1) inverse correlation between TOC400/ROC and δ13C links thermal stability and soil organic matter (SOM) composition; 2) direct correlation between carbonate breakdown temperature and δ13C denotes the mineralogical association of the inorganic pool. The results give clues regarding the nature and evolution of soil carbon pools.

The Ordinary Least Squares (OLS) regression is the most common method for fitting the δ2H-δ18O relationship. Recently, various studies compared the OLS regression with the Reduced Major Axis (RMA) and Major Axis (MA) regression for precipitation data. However, no studies have investigated so far the differences among the OLS, RMA, and MA regressions for water types prone to evaporation, mixing, and redistribution processes. In this work, we quantified the differences in terms of slopes and intercepts computed by the OLS, RMA, and MA methods for rainfall, snow and ice, stream, spring, groundwater, and soil water, and investigated whether the magnitude of such differences is significant and dependent on the water type, the datasets statistics, geographical or climatic characteristics of the study catchments. Our results show that the differences between the regression methods were largest for the isotopic data of some springs and some stream waters. Conversely, for rainfall, snow, ice, and melt waters datasets, all the differences were small and, particularly, smaller than their standard deviation. Slopes and intercepts computed using the different regression methods were statistically different for stream water (up to 70.4%, n = 54), followed by groundwater, springs, and soil water. The results of this study indicate that a thorough analysis of the δ2H-δ18O relationship in isotope hydrology studies is recommended, as well as considering the measurement errors for both δ2H and δ18O, and the presence of outliers. In case of small measurement errors and no significant differences between the slopes computed through the three methods, we suggest the application of the widely used OLS regression. Conversely, if the computed slopes are significantly different, we recommend investigating the possible reasons for such discrepancies and prefer the RMA over the MA approach, as the latter tends to be more sensitive to data with high leverage (i.e., data points with extreme δ18O values).

The presented research highlights relationships between the climatic anomalies that occurred in northern Italy in 2015 and the water system of Po river. We investigated the effect of anomalous high temperature and paucity of meteoric precipitation on the Po river discharge and water geochemistry. The new geochemical data, carried out on river water sampled at Pontelagoscuro (close to the city of Ferrara) and in the delta, have been compared with an extended dataset collected since 2009. The comparison emphasizes that water samples of 2015 were characterized by a high electrical conductivity due to high concentrations of conservative ionic species (e.g. Na, Cl, SO4) and nutrients such as nitrate. Oxygen and hydrogen isotopes, particularly sensitive to the observed climatic changes, reveal in a δ18O-δD diagram evaporative trends (highlighted by displacement from the Meteoric Water Lines) with a magnitude that was not recorded in the last years. The monitoring is currently in progress to develop functions that relate geochemical parameters to the evolving meteo-hydrological conditions.

The carbon elemental concentration (C wt%) and isotopic (δ13C ‰) composition of mantle xenoliths from the Tallante and Calatrava volcanic occurrences (in South-East and Central Spain, respectively) have been investigated to identify carbon sources and processes occurring in distinct geodynamic settings of the Iberian Peninsula. The peridotitic mantle xenoliths from Calatrava show elemental C ranging from 0.11 to 2.87 wt% which is coupled with a continuous isotopic variation from very negative values (δ13C − 26.1‰) to typical mantle values (δ13C − 5.9‰). On the other hand, the Tallante mantle xenolith suite displays lower C contents (0.06–0.15 wt%) showing a tighter variation with 13C-depleted values ranging between − 20.1 and − 23.7‰; higher elemental C up to 0.41 wt% displaying distinctly less negative isotopic values (δ13C between − 13.8 and − 11.9‰) have been recorded in veins crosscutting Tallante peridotites, plausibly representing the product of metasomatic reactions. The data from the two investigated xenolith suites invariably display a good correlation between elemental and isotopic composition, suggesting a mantle origin for carbon and Rayleigh-type fractionation as the process responsible for the observed C-δ13C variation. However, the correlation between the carbon isotopic data with other isotopic tracers (e.g. 87Sr/86Sr, 3He/4He) used to identify distinct mantle components and metasomatic reactions, indicates systematic differences between the two xenolith suites suggesting that beneath the Betic Cordillera (where Tallante is located) the deep C-cycle involves recycling, via subduction preceding/accompanying continental collision, of crustal components back in the mantle. Coherently, geochemical trends observed in the Tallante xenoliths seem to be influenced by metasomatic agents generated by melting of crustal lithologies that according to the analysis of a metasedimentary xenolith can contain C up to 1.2 wt% having δ13C of ca. − 18.0‰.

A comprehensive petrological and geochemical dataset is reported in order to define the thermo-compositional characteristics of Ti (Fe)-enriched picrite–basalt lavas (HT2, TiO 2 3–7 wt%), erupted close to the axial zone of the inferred Afar mantle plume, at the centre of the originally continuous Ethiopian–Yemeni CFB plateau (ca. 30 Ma) which is zonally arranged with progressively lower Ti basalts (HT1, TiO 2 2–4 wt%; LT, TiO 2 1–3 wt%) toward the periphery. Integrated petrogenetic modelling based on major and trace element analyses of bulk rocks, minerals, and melt inclusions in olivines, as well as Sr–Nd–Pb–He–O isotope compositional variations enables us to make several conclusions. 1) The phase equilibria constraints indicate that HT2 primary picrites were generated at ca. 1570 °C mantle potential temperatures ( T p ) in the pressure range 4–5 GPa whereas the HT1 and LT primary melts formed at shallower level ( T p 1530 °C for HT1 and 1430 °C for LT). Thus, the Afar plume head was a thermally and compositionally zoned melting region with maximum excess temperatures of 300–350 °C with respect to the ambient mantle. 2) The HT2 primary melts upwelled nearly adiabatically to the base of the continental crust (ca. 1 GPa) where fractionation of olivine, followed by clinopyroxene, led to variably differentiated picritic and basaltic magmas. 3) Trace element modelling requires that the primary HT2 melts were generated—either by fractional or batch melting (F 9–10%)—from a mixed garnet peridotite source (85%) with 15% eclogite (derived from transitional MORB protoliths included in Panafrican terranes) that has to be considered a specific Ti–Fe and incompatible element enriched component entrained by the Afar plume. 4) The LT, HT1, and HT2 lavas have 143 Nd/ 144 Nd = 0.5131–0.5128, whereas Sr–Pb isotopes are positively correlated with TiO 2 , varying from 87 Sr/ 86 Sr 0.7032 and 206 Pb/ 204 Pb 18.2 in LT basalts to 87 Sr/ 86 Sr 0.7044 and 206 Pb/ 204 Pb 19.4 in HT2 picrite–basalts. High 3 He/ 4 He (15–20 R A ) ratios are exclusively observed in HT2 lavas, confirming earlier evidence that these magmas require a component of deep mantle in addition to eclogite, while the LT basalts may more effectively reflect the signature of the pre-existing mantle domains. The comparison between high-MgO (13–22%) lavas from several Phanerozoic CFB provinces (Karoo, Parana–Etendeka, Emeishan, Siberia, Deccan, North Atlantic Province) shows that they share extremely high mantle potential temperatures ( T p 1550–1700 °C) supporting the view that hot mantle plumes are favoured candidates for triggering many LIPs. However, the high incompatible element and isotopic variability of these high-MgO lavas (and associated CFB) suggest that plume thermal anomalies are not necessarily accompanied by significant and specific chemical effects, which depend on the nature of mantle materials recycled during the plume rise, as well as by the extent of related mantle enrichments (if any) on the pre-existing lithospheric section.

A critical review of the available multidisciplinary data on the Parana-Etendeka Province allows for the reconciliation of the controversial aspects of its origin in a coherent tectonomagmatic scenario, in which continental flood basalt (CFB) magmatism evolved from the Parana plateau s.s. (Stage 1) to progressive continental rifting in Etendeka (Stage 2), and then opened to the South Atlantic at the same latitude; the CFB magmatism is triggered by the prolonged impingement of the proto Tristan plume on the western Gondwana lithosphere. The provinciality of the CFB is evidenced by the incompatible element distribution and Sr-Nd-Pb isotopic data, where the Parana and Etendeka magmas are more akin to lithospheric and asthenospheric (plume-related) components, respectively. Stage 1 consisted of the rapid outpouring of the Parana Plateau s.s. CFB (135–134 Ma, ~ 800,000 km3, and eruption rate ~0.8 km3/a) that was zonally arranged with prevailing high-TiO2 (HT) basalts in the central-northern part and low-TiO2 (LT) suites at the southern periphery. The differentiated nature (MgO = 8–4%) of these plateau magmas suggests the variable extent of fractional crystallisation during rise through a relatively thick lithosphere. Petrological modelling, isotopic signatures (87Sr/86Sr 0.70483–0.70620, and eNd(t) from −1.27 to −5.78), and incompatible element distributions approaching the EM1 mantle component suggest that the HT and LT Parana basalts may be derived from mantle sources located in the lower lithosphere at P 3–4 GPa and a potential temperature (Tp) of 1500–1550 °C. The high Tp recorded (and the relative Texcess 250–300 °C thermal anomaly) can be attained after several million years of lithospheric heating, beginning from the first plume impact, which is represented by precursor alkaline events (145–138 Ma) at the westernmost border of the Parana plateau. The subsequent rifting (Stage 2, mostly 134–128 Ma) developed SE of the Parana plateau in relation to the NW drifting of the Gondwana plate over the rising plume and was accompanied by progressive lithospheric arching, thinning, and rifting, which culminated in continental breakup close to the Etendeka border. The concomitant and exclusive appearance, in both the HT and LT suites of this region, of the hottest and deepest (Tp up to ~1590 °C and P up to ~5 GPa) high-MgO sub-lithospheric magmas (87Sr/86Sr 0.70319–0.70533 and eNd(t) from 9.08 to 0.53) is consistent with their generation from the axial zone of the upwelling plume. The basic–acidic bimodal character of CFB magmatism, since the beginning of this stage, must be related to the intensive block faulting of the rifted margins that favoured magma trapping and crystal fractionation to trachydacite and dacite-rhyolite differentiates from the respective HT and LT basalts. Owing to the higher SiO2 and viscosity, the prevailing dacite-rhyolite magmas were more prone to pond in crustal magma chambers, where they experienced assimilation fractional crystallisation (87Sr/86Sr 0.71466–0.72558 and eNd(t) from −5.50 to −9.31) before erupting as extensive rheo-ignimbrites. During the final rifting stage, CFB activity continued until 128 Ma (with sporadic episodes until 122 Ma), and the plume dynamic support gradually vanished beneath the two conjugate South American/South African continental margins, up to the opening of the South Atlantic and hot-spot volcanism of the Rio Grande and Walvis Ridges.

Sulfide mineralization in the province of Trento (northeastern Italy) includes various mineral assemblages that are often silver-rich and have been exploited in different phases from the Middle Ages until the 20th century. This study investigates mineralized rocks from three historically important sites (Calisio mount, Erdemolo lake, and the locality of Cinque Valli), providing new analytical data (Inductively Coupled Plasma-Mass Spectrometry on bulk rocks, and Scanning Electron Microscopy on thin sections) that demonstrate that parageneses do not only include galena, chalcopyrite, and sphalerite but also accessory minerals, such as tetrahedrite, tennantite, acanthite, and sulfosalts (matildite/polybasite). This explains the high content of As (up to 278 ppm), Bi (up to 176 ppm), and Sb (up to 691 ppm) that are associated with Pb–Cu–Zn mineralization. Notably, trace-element ratios indicate that, although closely associated from a geographical point of view, the studied sites are not genetically related and have to be referred to in distinct mineralization events, possibly induced by three diverse magmatic and hydrothermal phases that occurred in the Variscan post-orogenic setting. Besides geological and petrogenetic reconstruction, the new data outline potential geochemical risks, as they reveal a high concentration of elements characterized by marked toxicity that can be transferred into the local soil and water. Therefore, future studies should be devoted to better investigating the metal distribution in the surroundings of ancient mining sites and their geochemical behavior during the weathering processes.

Manuella et al. (2015) emphasize that the Hyblean xenolith suite includes only ultramafic (peridotites and pyroxenites) and mafic (gabbros s.l.) lithotypes, whereas felsic rocks are not observed. On this ground, they attest that rocks having a “continental” affinity are totally absent within the Hyblean basement. This statement can be criticized for various reasons because the representativeness of the crust provided by the xenoliths is often biased, as xenolith populations worldwide are often monotonous, i.e., mainly represented by a limited number of lithologies (see also Rudnick and Fountain 1995; Coltorti et al. 2011). The observation suggests that: host magmas entrained xenoliths at a specific depth, and not all along the path toward the surface. The restricted type of lithologies is generally ascribed to the mechanism of xenolith uptake, which is related to the fluid (mainly CO2) release and bubble nucleation, which trigger discrete event of crack formation and breaking of the surrounding host rocks; in other words, fluid nucleation leads to “explosion,” fracturing the wall rocks and forming the xenoliths (Lensky et al. 2006); the specific depth of xenolith formation is distinctive of each magma type, and usually Cenozoic alkaline basalts of the Mediterranean region entrain xenoliths from either the uppermost lithospheric mantle or the lower crust (at ca 30–50 km depth), whereas sampling of shallower depths is rarer (Beccaluva et al. 2005); basic magmas easily resorb and assimilate felsic rocks as indicated by experimental and numerical modeling (Sachs Introduction

article i nfo Article history: Detailed petrological and geochemical investigations of an extensive sampling of mantle xenoliths from the Neogene-Quaternary Bir Ali diatreme (southern Yemen) indicate that the underlying lithospheric mantle consists predominantly of medium- to fine-grained (often foliated) spinel-peridotites (85-90%) and spinel-pyroxenites (10-15%) showing thermobarometric estimates in the P- Tr ange of 0.9-2.0 GPa and 900-1150 °C. Peridotites, including lherzolites, harzburgites and dunites delineate continuous chemical, modal and mineralogical variations compatible with large extractions of basic melts occurring since the late Proterozoic (~2 Ga, according to Lu-Hf model ages). Pyroxenites may represent intrusions of subalkaline basic melts interacting and equilibrated with the host peridotite. Subsequent metasomatism has led to modal changes, with evidence of reaction patches and clinopyroxene and spinel destabilization, as well as formation of new phases (glass, amphibole and feldspar). These changes are accompanied by enrichment of the most incompatible elements and isotopic compositions. 143 Nd/ 144 Nd ranges from 0.51419 to 0.51209 (eNd from +30.3 to �10.5), 176 Hf/ 177 Hf from 0.28459 to 0.28239 (eHf from +64.4 to

The deep seated xenolith association exhumed in the Pliocenic volcano of Tallante (Betic Cordillera, Spain) includes protogranular mantle peridotites, felsic (metasedimentary) crustal rocks, as well as cumulus igneous rocks such as norites and amphibole (+/- phlogopite)-clinopyroxenites. The whole xenolith suite equilibrated at the same pressure (0.7-0.9 GPa) representing the local crust-mantle boundary (MOHO) characterized by extreme lithological heterogeneity. This heterogeneity resulted from orogenic processes that induced the juxtaposition of crustal rocks (variably depleted in fusible components) within mantle domains including metasomes, as it is commonly observed in orogenic mantle massifs of the Mediterranean area. In this contribution, we report new mineral compositions of igneous parageneses recorded in these xenoliths, and we present Sr-Nd isotope data on both igneous and metasedimentary xenoliths that integrate those from the literature. Sr-Nd isotopes coherently indicate a restitic character of the metasedimentary xenoliths, which according to model ages were affected by partial melting in Paleozoic times. Sr-Nd isotopic errorchrons on the igneous xenoliths, on the other hand, qualitatively indicate Tertiary ages, which are corroborated by U-Pb zircon datings of one norite xenolith and two composite xenoliths having zircon-bearing norite veinlets. The new data are discussed proposing that MOHO lithologies of Tallante could provide significant source compositions for the genesis of the Neogene volcanics of the Betic area, which included calcalkaline lavas as well as more potassic products such as lamproites. (C) 2015 Elsevier B.V. All rights reserved.

A careful review of petrological and geochemical data on the Parana-Etendeka igneous province is reported, with particular attention being devoted to the relationships between high-MgO CFB (tholeiitic basalts-picrites) and nearly coeval alkaline-carbonatite complexes linked to the same extensional tectonics on a regional scale. At 135–130 Ma, the tectonomagmatic activity was focused in Etendeka, the centre of the restored province, and characterised by an exclusive occurrence of the hottest and deepest high-MgO CFB (potential temperature T p up to 1590 °C and pressure up to 5 GPa) possessing the same Sr-Nd-Pb isotopic composition of the “Gough” geochemical component, a marker of the initial Tristan plume activity. Etendeka high-MgO CFB thus represent the most genuine proxies of sublithospheric melts generated at the plume axis and are relatively unaffected by lithospheric contamination. Nearly coeval (133–128 Ma) alkaline‑carbonatite complexes cluster around the extensional structures of the Ponta Grossa Arch (e.g., Jacupiranga and Juquia in Brazil) and the Damara Belt (e.g., Erongo, Okurusu, Okenyenya and Paresis in Namibia), both of which intersect the early track of the south Atlantic opening. Compared to high-MgO CFB, alkaline magmas display distinctive isotopic signatures and an incompatible element distribution consistent with their generation from lithospheric mantle sources, which were variably metasomatised (veined?) by amphibole and phlogopite. Metasomes of alkaline mantle sources have a HIMU affinity and are dominated by amphibole in Namibia, whereas they display EM1 tendency and a more relevant role of phlogopite in Brazil, which implies important lithospheric differences at a regional scale. The tectonomagmatic features of Parana-Etendeka –also shared by other Gondwana LIPs, such as Deccan and Karoo– can be reconciled by a generalized model where a hot plume impinging on a relatively thick lithosphere caused, in the axial zone, the contemporaneous generation and rise of high-MgO CFB and alkaline magmas from distinct asthenospheric and lithospheric mantle sources, respectively. In the asthenosphere, the volatile-poor solidus was crossed under an adiabatic thermal regime, mostly in the range of 4 to 5 GPa and T p 1500 to 1600 °C with the development of high-MgO CFB. In the overlying metasomatised lithosphere, the plume effects caused a perturbation of the conductive thermal regime and a crossing of volatile-rich solidus (mostly P 2–3 GPa, T p 1300–1400 °C) with the generation of alkaline melts from the most fusible (hydrated and carbonated) mantle domains.

Air pollution constantly threatens the conservation of stone used in historic built heritage of urban areas. Previous studies on pollution impact focused mainly on marble and limestone, due to their low porosity and chemical homogeneity, by analysing samples collected from historic buildings or performing tests in simulation chamber and/or in field. However, gaps still exist in measuring deposition fluxes on materials and developing proper solutions for long-term management of cultural heritage. Furthermore, the possible repercussions on built heritage of the current atmosphere, poorer than in the past of SO2 but richer of NOx and organic compounds, merit consideration. Two years-long field exposure tests with model samples are currently under execution in Italian cities (Bologna, Ferrara, Florence) characterized by different environmental conditions as a non-invasive methodological approach for studying the impact of urban pollution on carbonate stones. The selected methodological approach as well as first available results on exposed samples after the first year of exposure will be discussed. Marble (Carrara Marble) and limestone (Red Verona Marble) were selected as model samples as they were widely used as construction and ornamental elements in historic Italian architecture. Galvanized metallic racks were prepared to host samples with different exposure orientations (i.e. horizontal, oblique and vertical) in order to identify how positioning may reflect on deposition and removal of pollutants. Stone samples were exposed outdoor, partially sheltered from the rain wash-out, in areas strongly affected by pollution due to vehicular traffic. At predefined time intervals, the exposed soiled specimens undergo mineralogical, petrographic and geochemical analyses (Optical Microscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Analysis, Inductively Coupled Plasma Mass Spectrometry, Ion Chromatography analysis and Thermal-chemical methodology using a CHNSO combustion analyzer (Ghedini et al., 2006)) to characterise the damage products (typology, origin) due to the impact on stones by gaseous pollutants and carbon/soluble fractions of aerosol. Moreover, a connection between the deposited soluble and carbon fractions and changes of colorimetric parameters will be assessed for setting up damage functions, by performing colorimetric analysis. Simultaneously passive sampling of aerosol has been designed by the exposure of filters while seasonal environmental monitoring campaigns of particulate matter will allow to compare soluble ions and carbon fractions present into atmosphere with that actually accumulated on samples surface. References Ghedini N., Sabbioni C., Bonazza A. and Gobbi G., Chemical-Thermal quantitative methodology for carbon speciation in damage layers on building surfaces, Environmental Science and Technology, 40 (2006), 939-944.

Strontium isotopic composition (Sr-87/Sr-86) of river water provides insight on the nature of rocks involved in the weathering processes and important constraints for reconstructing silicate versus carbonate weathering in large scale basins. New data, presented in the context of a geochemical map of the Po river basin, highlight that the Po river water evolves from the upper part of the catchment, where Sr-87/Sr-86 approaching 0.7097 relates to the weathering of igneous and metamorphic silicate rocks, to the middle part, where less radiogenic compositions (Sr-87/Sr-86 similar to 0.7089) are driven by the confluence of the tributaries draining Mesozoic carbonate rocks of the South Alpine domain and from inflow of Apennine streams characterized by less radiogenic Sr signatures due to weathering of marly sediments and mafic magmatic rocks. Down flow, the Sr isotopic compositions of Po river water rises at 0.7091 either by the confluence of the last Apennine tributary (Panaro, Sr-87/Sr-86 similar to 0.7095) and/or by the possible contribution from hyporheic exchanges. Po river isotopic signatures reveal slightly more radiogenic Sr-87/Sr-86 in comparison to other important Alpine river systems (e.g. Danube, Rhine and Rhone), likely suggesting that silicate rocks are comparatively contributing more weathering byproducts in the Po basin.

In the Republic of Macedonia, construction and demolition (C&D) waste is often dumped, underestimating the potential recycling and re-use as raw materials for civil engineering works and/or cement/ceramic industries. SAMCODE (Sustainable Approach to Managing Construction and Demolition Waste) is a know-how exchange program, the focus of which is chemical characterisation in terms of major and trace elements in order to evaluate the possible Macedonian C&D waste recycling. Thirty-nine C&D waste samples were collected from different dumps in Skopje and surroundings. X-ray fluorescence analyses, carried out on powdered samples, show i) highly variable concentrations, indicative of the heterogenous nature of C&D waste, and ii) high concentration in Cr, Ni, and Zn with respect to Italian, Chinese, and Dutch tolerance limits, probably due to the presence of these elements in ophiolitic rocks and sulphide-bearing deposits, used as raw material in building activity. Inductively coupled plasma mass spectrometry analyses of leachates, performed to assess the mobility of heavy metals, show significant concentrations of Cr, and to a lesser extent, Ni. Results suggest that homogenisation processes of the recycled materials should be implemented and preliminary screening of C&D waste should be performed to eliminate heavy metals-bearing components.

Calcium oxalate patinas have been sampled on architectural elements of two ancient churches located on Torcello Island (Venetian Lagoon) and subsequently analyzed. The site had been selected presenting patinas of exceptional amount and thickness, elsewhere generally found as thin alteration layers covering stone surfaces or within black crusts on monuments in urban environments. Optical and mineralogical analyses suggest that these patinas are not the result of a simple deposition process, but originate as surface “transformations” of the substrate, and are mainly composed of dihydrate calcium oxalate (weddellite) and gypsum. Among the experimental techniques, isotope analyses (C and S) have been specifically carried out aiming at achieving a better understanding of their origin and possible causes of formation. The observed carbon isotopic fingerprint reveals in fact a strong biological fractionation recorded in the oxalate patina (δ13C ranging from −22.3‰ to −28.0‰), almost exclusively attributable to C...

A comprehensive study including new field, petrological and geochemical data is reported on the Jacupiranga alkaline-carbonatite complex (133–131 Ma) which, together with other alkaline complexes, occurs in southern Brazil and is coeval with the Parana CFB province. It consists of a shallow intrusion (ca. 65 km2) in the Precambrian crystalline basement, and can be subdivided in two main diachronous plutonic bodies: an older dunite-gabbro-syenite in the NW and a younger clinopyroxenite-ijolite (s.l.) in the SE, later injected by a carbonatitic core (ca. 1 km2). An integrated petrogenetic model, based on bulk rock major and trace element analyses, mineral chemistry and Sr-Nd-Pb-C isotopic data, suggests that the two silicate intrusions generated from different mantle-derived magmas that evolved at shallow level (2–3 km depth) in two zoned cup-shaped plutonic bodies growing incrementally from independent feeding systems. The first intrusion was generated by OIB-like alkaline to mildly alkaline parental basalts that initially led to the formation of a dunitic adcumulate core, discontinuously surrounded by gabbroic cumulates, in turn injected by subanular syenite intrusive and phonolite dykes. Nephelinitic (± melilite) melts – likely generated deep in the lithosphere at ≥ 3 GPa – were the parental magmas of the second intrusion and gave rise to large coarse-grained clinopyroxenite ad- to meso-cumulates, in turn surrounded, and partially cut, by semi-annular fine-layered melteigite-ijolite-urtite ortho-cumulates. The available isotopic data do not evidence genetic links between carbonatites and the associated silicate intrusions, thus favouring an independent source from the mantle. Moreover, it may be suggested that, unlike gabbro-syenites and carbonatites, mostly generated from lithospheric mantle sources, the parental magmas of the ijolite-clinopyroxenite intrusion also record the influence of sublithospheric (plume-related?) geochemical components.

This paper demonstrates that geochemistry is useful for the identification of sediment origin and provenance in alluvial plains characterised by a complex hydrographic evolution. The study is focused on the northeastern Padanian plain (Italy), an area primarily characterised by sedimentary contributions from the two largest Italian river systems (Po and Adige), which intimately interacted during the last millennia. X-ray fluorescence analyses of 120 soils and alluvial sediments define three diverse geochemical affinities that have distinctive siderophile/chalcophile elemental ratios. The sample group characterised by high Ni/Zn and Cr/Pb values conforms to modern Po River sediments, whereas a second group showing low Ni/Zn and Cr/Pb values conforms to the geochemical signature of modern Adige River sediments. A third sample group defines a “transitional” affinity that represents a geochemical mixture of Po (70%) and Adige (30%) sedimentary end-members. Based on these geochemical features, it is possible to distinguish alluvial sediments of the Po River basin (Ni/Zn > 1.0 and Cr/Pb > 4.2) from those of the Adige River basin (Ni/Zn

The Betic Ophiolites consist of numerous tectonic slices, metric to kilometric in size, of eclogitized mafic and ultramafic rocks associated to oceanic metasediments, deriving from the Betic oceanic domain. The outcrop of these ophiolites is aligned along 250 km in the Mulhacén Complex of the Nevado-Filábride Domain, located at the center-eastern zone of the Betic Cordillera (SE Spain). According to petrological/geochemical inferences and SHRIMP (Sensitive High Resolution Ion Micro-Probe) dating of igneous zircons, the Betic oceanic lithosphere originated along an ultra-slow mid-ocean ridge, after rifting, thinning and breakup of the preexisting continental crust. The Betic oceanic sector, located at the westernmost end of the Tethys Ocean, developed from the Lower to Middle Jurassic (185–170 Ma), just at the beginning of the Pangaea break-up between the Iberia-European and the Africa-Adrian plates. Subsequently, the oceanic spreading migrated northeastward to form the Ligurian and Alpine Tethys oceans, from 165 to 140 Ma. Breakup and oceanization isolated continental remnants, known as the Mesomediterranean Terrane, which were deformed and affected by the Upper Cretaceous-Paleocene Eo-Alpine high-pressure metamorphic event, due to the intra-oceanic subduction of the Jurassic oceanic lithosphere and the related continental margins. This process was followed by the partial exhumation of the subducted oceanic rocks onto their continental margins, forming the Betic and Alpine Ophiolites. Subsequently, along the Upper Oligocene and Miocene, the deformed and metamorphosed Mesomediterranean Terrane was dismembered into different continental blocks collectively known as AlKaPeCa microplate (Alboran, Kabylian, Peloritan and Calabrian). In particular, the Alboran block was displaced toward the SW to occupy its current setting between the Iberian and African plates, due to the Neogene opening of the Algero-Provençal Basin. During this translation, the different domains of the Alboran microplate, forming the Internal Zones of the Betic and Rifean Cordilleras, collided with the External Zones representing the Iberian and African margins and, together with them, underwent the later alpine deformation and metamorphism, characterized by local differences of P-T (Pressure-Temperature) conditions. These Neogene metamorphic processes, known as Meso-Alpine and Neo-Alpine events, developed in the Nevado-Filábride Domain under Ab-Ep amphibolite and greenschists facies conditions, respectively, causing retrogradation and intensive deformation of the Eo-Alpine eclogites., This research was funded by Project CGL2009-12369 of the Spanish Ministry of Science and Innovation, co-financed with FEDER funds, and by Research Group RNM 333 of Junta de Andalucía (Spain)

Mantle xenoliths from Pliocene-Quaternary volcanic diatremes in the Azrou area (Middle Atlas, Morocco) include protogranular to porphyroclastic spinel lherzolites with superimposed metasomatic textures involving pyroxenes and spinel as the main reacting phases. Thermobarometric estimates on these xenoliths show pressure ( P )–temperature ( T ) equilibrium conditions in the range 1.1–1.4 GPa and 900–1090 °C. Bulk rocks have flat heavy rare earth element (HREE) patterns (0.6–2.2 times chondrite) and are variably enriched in light REE (LREE; La N /Yb N between 1.1 and 15.6). The constituent clinopyroxenes are characterized by flat HREE distributions (5.1–11.9 times chondrite) and variable LREE enrichment with La N /Yb N from 0.4 to 25, which generally conform to the bulk rock chemistry. Trace elements characteristics of the metasomatised clinopyroxenes suggest that the metasomatasing agents were highly alkaline carbonate-rich melts such as nephelinites/melilitites or, as extreme, silico-carbonatites. Sr–Nd isotopic composition analyses carried out on clinopyroxene separates yield 87 Sr/ 86 Sr = 0.70243–0.70335, 143 Nd/ 144 Nd = 0.51273–0.51325. The helium isotope composition of olivines ranges from 6.2 to 6.8 R a . These values, coupled with the radiogenic lead isotopic composition available in the literature, suggest that the Middle-Atlas lithospheric mantle interacted with HIMU-like metasomatic components. These are in turn related to local mantle upwellings along pre-existing tectonic lineaments – located at the northern border of the West African Craton – that were reactivated as far-field foreland reaction of the Africa-Europe collisional system.

Purpose This contribution investigates agricultural soils and sedimentary deposits in the province of Ferrara (Padanian alluvial plain, Northern Italy) in order to: examine their genesis; to define the geochemical background of the area; and to evaluate the existence of anthropogenic contamination. Moreover, environmental risk related to the presence of potentially toxic heavy metals that can be transferred into agricultural products (and consequently bio-accumulated in the food chain) was also assessed.

The year 2017 was anomalously warm and dry across the whole Italian Peninsula, and the paucity of precipitation was emphasized during the extreme summer drought of the main Italian river, i.e., the Po river, which was characterized by a discharge persistently below 600 m3/s (in spite of the average discharge of 1500 m3/s). During these extreme conditions, the Po river oxygen and hydrogen stable isotopes (&delta, D, &delta, 18O) displayed a relation (&delta, D = 6.1*&delta, 18O &minus, 6.6) significantly different from that recorded in the previous investigation of the years 2012&ndash, 2014 (&delta, D = 7.5*&delta, 18O + 6.5). The lowering of the slope and the negative intercept clearly reflect the transition toward arid conditions that characterized the investigated period. The difference is expressed by the derivative parameter Line-Conditioned excess (LC-exc), which better describes the compositional difference of Po river water in the year 2017 with respect to that of the period 2012&ndash, 2014, when the system was less affected by warm or dry conditions and the river discharge was more similar to the historical trends. The isotopic anomaly observed in 2017 throughout the river is even greater in the terminal part of the river, where in the meanders of the deltaic branches, the river flow progressively slows down, suffering significant evaporation. The isotopic signature of the water appears, therefore, an appropriate tool to monitor the watershed response to evolving environmental conditions. These sensitive isotopic parameters could be interpreted as &ldquo, essential climate variables&rdquo, (ECV) that are physical, chemical, or biological geo-referenced parameters that critically contribute to the characterization of Earth&rsquo, s climate. Future research needs to find relationships between ECV (including the water stable isotopes) and the evolution of ecosystems, which especially in the Mediterranean area, appear to be fragile and severely affected by natural and anthropogenic processes.