No abstract

No abstract

; +3909123861639; +393479662844 A bstract Venere Lake, in the Pantelleria Island thermal system (Central Mediterranean Sea) consists of a mix of seawater and hydrothermal volcanic fluids containing high levels of dissolved SiO 2. Close to the lake's thermal springs, siliceous stromatolites are deposed under high bacterial activity conditions whereas roughly interlaminated Ca-carbonates and microbial mats are widely scattered in the lake. The dissolved REE speciation in lake waters is dominated by [REE(CO 3) 2 ]-, [REE(CO 3)] + and [REE(H 3 SiO 4)] 2+ complexes. On the contrary the most abundant Zr and Hf species are hydroxyl-and fluoride-complexes. The behavior of REE Zr and Hf in the Venere lake waters is controlled by precipitation of amorphous silica, carbonates and bacterial activity.

Groundwater from karst circulation systems of Central Italy were sampled and analyzed, in 2018, for delineating a preliminary, general geochemical framework of their relationship with neotectonics, in an area characterized by a frequent and often destructive seismicity. We determined field physical-chemical parameters, concentrations of main dissolved ions and gases and isotopic composition of water (δ18O, δD) and total dissolved inorganic carbon (δ13C TDIC). We discriminated between “normal” hydro-karst systems and multi-component aquifers, composed of meteoric groundwater that have also interacted with rocks of different lithological nature and/or deep fluids. These multicomponent aquifers are of potential interest in the monitoring of neotectonics activity, because changes in the stress field associated with the preparatory phase of an earthquake may affect the permeability of rocks, in turn causing variation of their chemical-isotopic character. The geographical distribution of these aquifers seems to be controlled by tectonics. In fact, the Olevano–Antrodoco–Sibillini thrust separates the more anomalous sites, located westwards of it, from the groundwater bodies at its eastern side, showing a more typical karst character.

No abstract

No abstract

No abstract

Abstract. On 11 August 2008 a paroxysmal eruption occurred at Santa Barbara mud volcano (MV), located close to Caltanissetta, one of the most densely populated cities of Sicily (Italy). An associated minor event took place on August 2009. Both the events caused severe damage to civil infrastructures located within a range of about 2 km from the eruptive vent. Geomorphological, geochemical, and seismological investigations were carried out for framing the events in the appropriate geodynamic context. Geomorphological surveys recognized, in the immediate surrounding of the main emission point, two different families of processes and landforms: (i) ground deformations and (ii) changes in morphology and number of the fluid emitting vents. These processes were associated to a wider network of fractures, seemingly generated by the shock wave produced by the gas blast that occurred at the main paroxysm. Geochemical characterization allowed an estimation of the source of the fluids, or at least their last standing, at about 3 km depth. Finally, the close time relationships observed between anomalous increments of seismic activity and the two main paroxysmal events accounted for a possible common trigger for both the phenomena, even with different timing due to the very different initial conditions and characteristics of the two processes, i.e. seismogenesis and gas overloading.