United States

It’s now recognized that a global climate change is taking place, leading to an increase in temperatures and a variation in precipitation regime, also affecting groundwater (GW) (Taylor et al., 2013).  In this study we want to evaluate how climate change affects GW temperature in the Piedmont Po plain (NW Italy). The Piedmont Po plain covers the 27% of the whole region and it’s the most important GW reservoir of the Piedmont region (De Luca et al., 2020). It consists, from top to bottom, by Alluvial deposit complex (lower Pleistocene-Holocene), that hosts a shallow unconfined aquifer, the “Villafranchiano” transitional complex (late Pliocene-early Pleistocene), that hosts a multilayered aquifer, and a Marine complex (Pliocene) hosting a confined aquifer (De Luca et al., 2020). For this research, 41 wells in the shallow aquifer and 20 weather stations were selected throughout the Piedmont Po plain area, and GW and air temperature parameters were analysed for the period 2010-2019. The GW temperature data were firstly studied with basic statistical analysis (mean, maxima, minima) and then with the Mann-Kendall and Theil-Sen methods to evaluate the trend of the monthly mean GW temperatures. GW temperatures show a general increase in all the plain, up to a maximum of 2.18 °C/10 years. The same analyses were carried out for the air temperature data and it was observed that the increases vary between 1.52 and 2.11 °C/10 years. Then to compare water and air temperature, the Voronoi polygons method was used on QGis by centring the polygons on the weather stations. From this comparison, it was possible to highlight that in most cases (37 on 41, thus 90% of the analysed couples of temperature data) there is a greater increase in the monthly mean air temperatures than in the monthly mean GW temperatures. The same behaviour was observed for the monthly minima and maxima GW and air temperature. These results testify a greater resilience of GW temperature to climate variability. Future insights will be a detailed analysis of the factors influencing the more or less evident increase in GW temperatures in relation to air temperatures (e.g. depth of the water table, position of the monitoring well, position of the probe inside the well...).

SGI 2021

The impact of climate change on groundwater temperature of the Piedmont Po plain (NW Italy): preliminary results

**Attenzione, gli orari riportati nel PROGRAMMA (icona calendario) si riferiscono al fuso orario locale dell’utente. Il fuso orario ufficiale del Congresso è Central European Time (CET).**

L'Istituto Nazionale di Oceanografia e Geofisica Sperimentale - OGS e il Dipartimento di Matematica e Geoscienze dell'Università di Trieste sono orgogliosi di ospitare il 90° Congresso della Società Geologica Italiana a Trieste dal 14 al 16 settembre 2021. La modalità del congresso è interamente online.

Con il motto "Geologia senza frontiere" questo evento mira a promuovere le Scienze della Terra come disciplina scientifica proiettata nel futuro, oltre i confini geografici, politici e disciplinari, per comprendere meglio l'interno del Pianeta Terra e la struttura del sottosuolo, difendere la società da pericolosi eventi geologici, comprendere meglio la variabilità climatica, pianificare l'utilizzo delle georisorse in modo etico e nel rispetto dell'ambiente.


**Please note, times listed in the SCHEDULE tab (calendar icon) reflect YOUR LOCAL TIME ZONE. The main timezone for this conference will be Central European Summer Time.**

The National Institute of Oceanography and Experimental Geophysics - OGS and the Department of Mathematics and Geosciences of the University of Trieste are proud to host the 90th Congress of the Italian Geological Society in Trieste on 14-16 September 2021.  The Congress will be held entirely online.

With the motto "Geology Without Borders" this event aims to promote Earth Sciences as a scientific discipline projected into the future, beyond geographical, political and disciplinary boundaries, to better understand the interior of Planet Earth and the structure of the subsurface, defend society from dangerous geological events, better understand climatic variability, plan the use of geo-resources in an ethical way and respecting the environment.


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Earth Sciences should be understood not only as necessary for a better understanding of the interior of the planet Earth, but also as a defense of society from dangerous geological events, for the understanding of climatic variations, for the planning and use of georesources in a ethical and respecting and protecting the environment.

technical paper

Investigating the texture and chemistry of mantle xenoliths allow us to constrain the nature of the upper mantle, the mechanism that generate melts and the evolution of the lithosphere beneath regions where no samples were exposed by tectonic activity. Texture, as well as chemical composition and mineralogical paragenesis, reflects the temperature, pressure, stress conditions, melting and/or contamination events undergone before and during the entrapment in the host magma (Pearson et al., 2003). In particular, the distribution of glass pockets (blebs) and veins inside xenoliths, as well as the texture of silicate, oxide and sulphide phases seem to be important in understanding some aspects of mantle metasomatism (Coltorti et al., 2000; Hughes et al., 2016; Lenaz et al., 2017). Classic 2D thin section observation might overlook some textural and mineralogical features, like oriented distribution of some mineral phases, possible interconnection of glass pockets and veins, distribution and morphological features of accessory minerals like sulphides. Extending the textural analysis of mantle xenolith to three-dimensional scale is therefore a potentially powerful tool in petrography and petrology. By using a multi-scale 3D textural analysis through X-ray computed microtomography (micro-CT), we characterized three mantle xenoliths from different geodynamic settings (i.e. mobile belt zone, pericraton, oceanic hotspot). We used an approach structured in increasing steps of resolution, starting with conventional X-ray micro-CT imaging (voxel size: 30 mm) and moving on to phase-contrast synchrotron-based X-ray micro-CT to reach a voxel size of 0.9 mm. We performed several exercises to test the effectiveness of micro-CT imaging on textural characterization of mantle xenoliths, comparing the results with the observation of conventional optical microscopy. One of these exercises involve a model to simulate the random sectioning of several thin sections and estimate the probability of accurate modal classification. Furthermore, 3D models obtained allow us to collect several textural information that were impossible to determine in a 2D classification. For example, we identified: spinel layering in one sample (MG10x), presence of gas vesicles in glass of xenolith Bi4, and silicic glass scattered through sample FN38. Moreover, high-density volumes were detected in nodules MG10x and Bi4, showing no relation with the spinel layering in the first one and a preferential concentration along fractures in the latter one.

A comparative study between X-ray computed microtomography and thin sections observation of mantle xenoliths

The Mediterranean is one of the most complex convergent margins on Earth. Its recent tectonic history was characterized by the coexistence of different compressional and extensional phases associated with episodes of orogenesis, slab rollback, slab tearing and oceanic spreading. Since  the  late  1990s, numerous seismological studies have been carried out in the region aiming at imagining the isotropic and anisotropic structures of the upper mantle. Among the various imaging techniques, isotropic P-wave travel-time tomography was largely used. However, seismic anistropy is widespread throughout the Mediterranean area and neglecting its effects could introduce significant artefacts in the inversions that could bias our understanding of the Earth’s interior structure and dynamics. Here we discard the isotropic approximation and invert for both P-wave isotropic velocity anomalies and seismic anisotropic by using the method proposed by VanderBeek & Faccenda (2021). We find that the magnitude of the isotropic P-wave velocity anomalies are substantially reduced when inverting for seismic anisotropy. This suggests that lateral variations in temperature and/or composition are smaller that what can be inferred from isotropic tomographies. P-wave fast azimuths orient mostly parallel to the trend of the Balcanic and the Alpine orogens in Eastern and Central Europe, respectively. In the Central Mediterranean the P-wave fast azimuths are sub-parallel to the Oligocene/Miocene-to-present retreating direction of the Ionian trench which led to the opening of the Liguro-Provençal and Thyrrenian basins and rotation of the Corsica-Sardinia block. In synthesis, the pattern of the P-wave fast azimuths is largely consistent with the S-wave fast azimuths determined from the splitting of SKS waves and from Rayleigh waves. This poses further constraints on the interpretation of the regional geodynamic evolution and on the accuracy of the employed inverse method.

Teleseismic Anisotropic P-wave tomography of the Central Mediterranean

The Central Mediterranean region in the Tertiary was characterized by intermittent phases of subduction and collision, the opening of back-arc extensional basins (i.e., Liguro-Provençal, Alboran, and Tyrrhenian basins) and episodes of slab lateral tearing, segmentation and break-off that led to the currently complex geological setting. Although the shallow tectonic evolution of the region has been relatively well constrained by abundant geological data, several uncertainties persist about the mechanisms that generated the present-day surface morphology and deep slab geometry. In this study, we reproduce the recent large-scale evolution of the Central Mediterranean and the associated strain-induced upper mantle fabrics and seismic anisotropy combining geodynamic and seismological numerical modelling techniques. 3D petrological-thermo-mechanical numerical models have been carried out using the viscoplastic code I3MG (Gerya, 2019), to compute the LPO and the synthetic SKS splitting we use a modified version of D-REX (Kaminski et al., 2004) and the softwares package FSTRACK (Becker, 2006), respectively. The subduction models were designed and calibrated according to paleogeographic-tectonic reconstructions of 30 Ma and seismological observations from the Mediterranean region available in the literature. We test different initial configurations in order to optimize the fit between predicted and observed slabs position and obtain a final model configuration resembling the present-day surface and deeper structures. It is found that the opening of back-arc extensional basins in response to the south-eastward retreat of the Ionian slab is a common feature in all models and slab lateral tearing or break-off occurs when Adria continental margin enters the trench. More importantly, we show that structural heterogeneities within the Adria plate and/or the geometry of its Tyrrhenian passive margin have a profound impact on (i) the development of a slab window below the Central Apennines, (ii) the retreat of the Northern Apenninic trench till the Adriatic Sea, and (iii) the retreat of the Ionian slab till the present-day position. In general, this study highlights the importance of coupling macro-scale geodynamic modelling with micro-scale simulations of strain-induced upper mantle fabrics and seismological synthetics in order to better constrain the tectonic evolution of complex convergent margins such as the Central Mediterranean. 

Geodynamic and seismological modelling of the recent dynamics of the Central Mediterranean region

The use of renewables is of paramount importance for sustainable development and economic growth. In this context, shallow ground-sourced heat exchangers (GSHEs) coupled with geothermal heat pumps represent a valuable opportunity for heating and cooling systems both in urban and rural areas. The regions of the Central Italy affected by the 2016 seismic sequence (Mmax 6.5), while involved in the post-earthquake reconstruction, could greatly benefit from the installation of GSHEs, which are environmental-friendly and with two peculiarities among the renewables: (i) continuous source of thermal energy and (ii) landscape protection (GSHEs are not visible). Here the focus is set on the evaluation of the shallow geothermal potential for the southern sectors of the Marche Region, with the aim of producing maps favouring the knowledge of the heat that could be extracted through GSHEs from different rocks of the subsoil. As a first pilot area we selected the upper-middle portion of the Potenza river fluvial plain to quantitatively estimate the values of key parameters such as the thermal conductivity, the volumetric heat capacity of the subsoil and the specific heat extraction. We followed the methods described in Taussi et al. (2021), thus averaging the geothermal parameters values over the first 100 meters, i.e. the most common depth of GSHEs. In order to assign the representative values for the shallow heat exchange parameters, the local stratigraphy was reconstructed on the basis of the surveys and data (mainly geognostic drillings) made available by the Civil Protection, thanks to the completion of the third level of the seismic microzonation studies. This freely accessible database might represent a valuable tool and source of information for such shallow geothermal studies in many different areas, and thus we recommend its use, given the relatively easy availability. In addition, the possibility (and the reliability) to use geophysical surveys (such as MASW or HVSR analyses) data, typically available in such databases, will be tested in order to independently estimate and compare the values of the most relevant shallow geothermal parameters. Preliminary results indicate that higher values for thermal conductivity (> 1.9 W∙m-1∙K-1) and volumetric heat capacity (> 2.35 MJ∙m-3∙K-1) characterize the uppermost sector of the fluvial plain of the study area, especially those areas around San Severino Marche and the ridges corresponding to Treia and Pollenza, where the, respectively, carbonate and siliciclastic bedrocks occur at relatively shallow depths. The development of GSHEs for heating and cooling systems should be really regarded as an opportunity for the reconstruction of these areas hit by the 2016 earthquake.

Defining the shallow geothermal potential by using the seismic microzonation data: a case study from the Southern Marche Region to encourage a sustainable post 2016-earthquake reconstruction

In Ecuador, the Paute river basin is one of the most monitored due to its importance for the generation of hydroelectric energy (Amay & López, 2015). However, in recent years there have been problems related to dry seasons that limit the distribution of electrical energy for industrial and domestic purposes (Galárraga, 2000). The ETAPA company indicates a decrease in water quality in urban areas, since measurements were made in the upstream sections and in sections of rivers that cross the city of Cuenca (occupying 41.22% of the province) obtaining data that showed that the quality indices fall from an excellent-good classification for the high sections, to a good-average classification in the low sections (Amay & López, 2015). For this, it is essential to use hydrological simulation models in order to know the water dynamics that develops within a basin both in current and future conditions, one of them being the hydrological model known as SWAT, which was developed by the United States Department of Agriculture in conjunction with the University of Texas, whose objective is to quantify and predict the environmental impact that land use practices generate on the production of water (and its quality), sediments, nutrients and substances chemicals within a basin influenced by various factors such as the type and use of land and meteorological conditions (Ríos & Faustino, 2017). The aim of this study is to evaluate the efficiency of the SWAT model with respect to simulations of nitrates, organic phosphorus, dissolved oxygen, sediments and evapotranspiration using as reference data observed in continuous monitoring stations. The results showed that the correlation between the simulated and the observed data is practically null if a linear relationship were established between them (Pearson's correlation coefficient). On the other hand, the simulations overestimated the evapotranspiration, dissolved oxygen and sediment values; and underestimated the values ​​of nitrates and organic phosphorus, based on PBIAS%. The RSR statistical criterion indicates that the modeling performance is unsatisfactory for nitrates, evapotranspiration and dissolved oxygen; and it is very good for organic phosphorus and the sediments of the “Llaviuco” station, which was verified with the application of the NSE statistical criteria. It is worth mentioning that the modeling in SWAT for this case study in general can be classified as poor because an initial calibration or correction of the model was not performed.

Evaluation of the SWAT model with respect to different variables within the Tomebamba River sub-basin belonging to the Paute River Basin-Ecuador

Italy is the world's second-largest feldspar producer (3 million tons/year, 22% of total) and the world biggest importer (22% of global world trades) (European Commission). Since the strong demand is rapidly depleting the proven reserves in EU Member States, the EU ceramics sector is increasingly dependent on feldspar imports from Turkey. In the future, it will be necessary to find additional sources of feldspar or to further increase inter-continental transport. The ever-increasing demand for feldspar, for ceramics, glass and other industrial uses, therefore, requires the extraction of granite and considerable international trade flows. At present, Buddussò-Alà dei Sardi (Sardinia Region-Italy) is the most important granite production area in Italy, with 66 authorised quarries (12 active), 70% of regional granite production and more than 50% of total Italian production. However, granite mining activities cause serious environmental problems. In Italy, every year 350.000-400.000 m3 of raw granite are extracted (Lucarini et al, 2020) generating the same quantity of waste. Feldspar production and trade generate large amounts of pollutant and greenhouse gas emissions, due either to the energy consumption of mining activities or from the transport of the finished product from the exporting countries (mainly Turkey and China). The areas where quarries are active suffer from landscape degradation, due to incomplete compliance or non-compliance with quarry recovery plans, considering that opening new quarries is cheaper than moving large amounts of waste. Finally, granite mining accounts for huge amounts of soil consumption, as it requires large areas in which the quarry waste accumulates.

Recycling of granite scraps in Sardinia by innovative and economically-viable extraction technology in a context of circular economy

The realization of tunnels, boreholes or quarry drifts in evaporite terrains often brings to face issues related to the geological and physical peculiarities of these rocks. In particular, typical problems are caused by the swelling behaviour of anhydrite, the high solubility in water and the high heterogeneity of gypsum facies. All these problems are particularly evident in the framework of quarry exploitation: the stability of rock pillars in underground quarries requires dedicated investigations. This study proposes an analysis of the main parameters that may affect the stability of underground gypsum pillars, considering in particular the effect of material heterogeneity and relative humidity. With this aim, the study proposes an investigation of a strongly heterogeneous facies of gypsum from the Messinian Salinity Crisis (i.e. branching selenite facies from Monferrato area, NW Italy). The textural and microstructural heterogeneity of the material is described with different techniques (MIP and SEM analyses). The study then includes a series of ad hoc designed mechanical tests to quantify strength and creep in function of the relative humidity. Results show the clear influence of material heterogeneity on the mechanical response. To this intrinsic mechanical variability, the influence of an external parameter as the humidity is observed to generate an additional reduction of material strength and to increase the creep strain rate in the long term tests. The effect of all these elements in the framework of a real underground quarry site is eventually discussed.

Effect of material heterogeneity and environmental humidity on the stability of gypsum in underground quarries

Monitoring and analysis of groundwater levels in space and in time is one of the tools to evaluate the quantitative status of groundwater resources and identify the groundwater response to climate variability, possible alterations and critical cases (IAH, 2016). In this study daily groundwater levels (GWL) in 36 piezometers of the shallow unconfined aquifer, and rainfall (R) data of 26 rain gauges located in  the Piedmont plain (western Po Plain, NW Italy) were collected in 2002-2017 interval and analyzed. Monthly and yearly aggregated data were then elaborated. Four methods for the analysis of groundwater resources status were applied to GWL: trends identification with the application of the non-parametric Mann-Kendall test, change-points research with the application of Pettitt test, percentiles method proposed by ISPRA (ISPRA, 2017) and non-standardized anomalies analysis. The same analysis were applied to R time series. For GWL and R time series, correlations with monthly lags and coefficient of variation of the maximum annual fluctuations, were also evaluated. The application of different methods to the GWL series permitted to clarify the GWL evolution in time and the spatialization of results allowed us to identify four areas with a similar hydrodynamic behaviour and resource status: south-eastern sector (Alessandria plain), north-northeast sector (Vercelli-Novara plain - rice fields), western sector (Turin plain) and south-west sector (Cuneo plain). Furthermore, the most critical areas were identified and some potential factors (anthropic, geological and hydrogeological) conditioning the hydrodynamic behaviour of the water table levels were highlighted. All the methods identified a critical situation in the Alessandria plain. In addition, the comparison between R and GWL results provided information on the timing and pattern of aquifer recharge, the hydrodynamic behaviour of GWL and their link with R variability. At last, this multi-criteria approach allowed to highlight advantages and limits of the applied methods. Finally, the application of different methodologies made it possible to evaluate not only the state of the resource by highlighting possible trends and critical situations, but also the real impact of rainfall variations on GWL variations and to assess how and with what delay GWLs respond to rainfall. Future insights will analyse the effects of other natural factors (air temperature, evapotranspiration, snowmelt) and anthropogenic variables (extent of withdrawals), with an in-depth analysis of the local hydrogeological and geological characteristics of aquifers.

Application of different statistical methods for analysis of groundwater levels in time:  spatio-temporal analysis in Piedmont plain (NW Italy) and comparisons with rainfall time series

This study proposes a survey methodology for identifying areas for combined Sustainable Drainage Systems (SUDS) and Aquifer Storage and Recovery (ASR) (Dearden et al. 2013, Sharp Jr., 1997); these techniques exploit the hydrogeological and geomorphological characteristics of an area, to increase the natural infiltration capacity of water into the ground. The target area is the city of Rome and the aim of such techniques is to solve the problems related to rainwater which, in case of extreme events, struggles to infiltrate the ground, overloads the undersized hydraulic systems and floods the urban space. The proposed method involves GIS geospatial analysis of various data: the permeability of outcropping lithology, the piezometric level of the aquifer, hydrogeological units, geomorphology and land use. To identify the suitable areas, areas characterised by high permeability and a piezometric level that would confer a volumetric capacity to possibly store even large quantities of water, without triggering possible problems associated with fluctuations in the water table, were identified. The data were divided into classes and indexed in order to compare and overlap them. Finally, hydrogeological units were also taken into account (by analysing their depth trend) in order to identify areas with similar characteristics of permeability with respect to depth. The latter will also be compared with the previous data to identify the areas suitable for SUDS and ASR. The final product of the suitable areas from a hydrogeological point of view will be compared with the land use map in order to exclude those areas that, for administrative and other legislative reasons, cannot be destined to this kind of activities.

Identifying areas suitable for Sustainable Drainage Systems and Aquifer Storage and Recovery to mitigate stormwater flooding phenomena in Rome (Italy)

In Naturally Occurring Asbestos (NOA) rich areas, weathering and erosion of asbestos-bearing rocks (e.g. meta ophiolites) are likely to cause water asbestos pollution: this may occur as a consequence of superficial and groundwater flow through natural rock formations containing NOA, depending on the characteristics of either the rocks and hence the water. Concerning groundwater management in NOA settings, asbestos pollution has to be considered with regard to water quality assessment: it represents an environmental problem and could even constitute a risk for human health. In fact, waterborne asbestos can come into contact with human beings as airborne fibres after water vaporization, or by ingestion, especially if they are present in drinking water. While a lot is known about diseases caused by airborne asbestos respiration (e.g. IARC, 2012), not enough has been yet understood about potential noxiousness of its ingestion. Consequently, a Maximum Contaminant Level for asbestos in potentially usable water has not been defined yet (WHO, 2020). To investigate possible groundwater pollution by asbestos due to natural environmental causes, a study area was selected in Piedmont, nearby NW Alps which are rich in NOA (and naturally occurring asbestiform minerals non-asbestos classified) (Belluso et al., 2019). In this area, two sampling and analysis campaigns regarding surface waters and groundwater were settled to investigate if, how and which type of mineral fibres could occur in water, trying to correlate them to the geolithological and hydrogeological characteristics of the area. The results of the two campaigns will be presented aiming to investigate asbestos and asbestiform fibres occurrence in water in relation to hydrochemical parameters, which are expression of the local hydrology and geolithology, and to evaluate seasonal variability. In addition, asbestos (and asbestiform) fibres transportation due to water flowing in NOA settings will be tested with a physical model, since a recent study highlighted possible asbestos mobility through soil (Mohanty et al., 2021): guidelines to create a flow model which describes mineral fibres mobility in porous aquifers will be presented following laboratory tests based on contaminated water circulation through packed columns.

Groundwater asbestos contamination in Naturally Occurring Asbestos (NOA) rich areas: a study on fibres characteristics, concentration and their possible mobility in aquifers

The impact of climate change on groundwater temperature of the Piedmont Po plain (NW Italy): preliminary results

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