87Sr/86Sr isotopes in grapes of different cultivars: A geochemical tool for geographic traceability of agriculture products

87Sr/86Sr was determined on fresh red and white grapes, soils and rocks from three selected vineyards to verify the isotopic relationships between the fruit of the vine and geologic substrata of vineyards.87Sr/86Sr were determined on sampled grapes of four different harvest years and different grape varieties, on bioavailable fraction of soils, on whole soils, and on bedrocks from the geo-pedological substratum of the vineyards. The vineyards chosen for the experimental works belong to an organic farming winery and thus cultivation procedures were strictly controlled. Grapes were sampled during the harvests of four different but consecutive years with87Sr/86Sr that does not change reflecting the values of the soil bioavailable fraction. No variations among grapes from different vine cultivars were observed. A strict isotope relationship with soil bio-available fraction was observed. These findings demonstrate the reliability of87Sr/86Sr, even at a very small scale, for food products geographic origin assessment

A comparative 87Sr/86Sr study in Red and White wines to validate its use as geochemical tracer for the geographical origin of wine

Recently high precision 87Sr/86Sr analyses have shown that Red wines keep the isotopic values of the vineyard substratum. Indeed, neither biological nor winemaking and aging processes are able to change the 87Sr/86Sr values through the oenological food chain from grapes to Red wine. In addition, 87Sr/86Sr of Red wines and those of rocks from the geological substratum of their vineyards correlate directly. The same holds not true for White wines, apparently. To investigate this discrepancy, 87Sr/86Sr has been determined for the entire production chain, from terroir to final product, of Red and White wines from the same vineyard. Sr-isotope data have been also determined for the young pyroclastic rocks of the geological substratum, and the soil of the vineyard to disambiguate the original contribution to the 87Sr/86Sr values of wines. Further Sr-isotope data have been determined on additives used for fining the White wine. The analytical results do not show significant differences between oenological food chains of Red and White wines. Preliminary data indicate that 87Sr/86Sr does not change passing from grape juices to wine in all cases under consideration. As a corollary neither yeast nor bentonite added during vinification of both Red and White wines do affect their Sr-isotopic values. On the other hand, 87Sr/86Sr of Red and White wines appears to be significantly lower than values observed in rocks of their substrata. Further experiments performed on this pilot winery would be useful to shed some lights on this issue

The bolsena-torre alfina geothermal field (Italy): a case of caldera-related blind geothermal resource

The Torre Alfina geothermal field is located about 10 km north of the Quaternary Bolsena caldera. The reservoir is a buried structural high made of Mesozoic-Cenozoic carbonatic sequences characterised by discontinuous secondary permeability and sealed by clay-rich alloctonous syn-orogenic flysch successions and Pliocene neo-authoctonous marine clays. The reservoir is locally highly productive, water-dominated and CO2-rich, with T at its top of 120 degrees C. The origin of the heat source was not investigated in detail but generally attributed to some unidentified deep magmatic body. Our field structural data document fracturing and faulting that affect both the reservoir and the seal units with dominant NE-SW and a subordinate E-W as maximum extension directions. The surface pattern and kinematics indicate that fault systems are part of the Pliocene-Quaternary tectonic episode in Central Italy, where strike-slip kinematics transfers deformation between main extensional shear zones. The fault network controls intense hydrothermal manifestations and travertine deposition north of the Torre Alfina area. 230Th/234U dating allows distinguishing three different stages of hydrothermal pulses bracketed between 200 and 90 ka. To improve the current understanding of the geometry and density of subsurface fracture system we applied the Shear Wave Splitting (SWS) technique studying the waveforms from local microearthquakes recorded in the area from 2008 to 2011. The analysis of SWS provides parameters directly related to the strike of the subsurface fluid-filled fractures and their density. According to the extensive-dilatancy anisotropy hypothesis (Crampin, 1984) SWS is generated by propagation through distributions of fluid-filled cracks, microcracks, and preferentially oriented pore space aligned according to the active stress field in the area. The analysis was made using the software ANISOMAT and gives a major direction NW-SE. The results agree both with structural data and with the focal mechanism of the earthquakes collected in the area between years 1977 and 1992. From the analysis on the crack density our data gives as result a good index of fracture for the reservoir’s rocks. Based on the updated conceptual model we performed numerical simulations in TOUGH2 code. Results indicate that deep circulation is forced by the geometry of the reservoir and by T and P gradients. We interpret the Torre Alfina field as a "blind" system, formed dominantly by lateral advection of heat and mass from the Bolsena caldera deep system driven both by high T and by the greater depth at which reservoir rocks are downthrown by the volcano-tectonic collapse. Preferential fracture fabric in the deep carbonates allows the lateral heat transfer. The cap-rocks have excellent sealing characteristics allowing the preservation of heat in correspondence with positive structural traps.PublishedKagoshima, Japan2T. Tettonica attiva5A. Energia e georisorse6A. Monitoraggio ambientale, sicurezza e territorioope

The bolsena-torre alfina geothermal field (Italy): a case of caldera-related blind geothermal resource

The Torre Alfina geothermal field is located about 10 km north of the Quaternary Bolsena caldera. The reservoir is a buried structural high made of Mesozoic-Cenozoic carbonatic sequences characterised by discontinuous secondary permeability and sealed by clay-rich alloctonous syn-orogenic flysch successions and Pliocene neo-authoctonous marine clays. The reservoir is locally highly productive, water-dominated and CO2-rich, with T at its top of 120 degrees C. The origin of the heat source was not investigated in detail but generally attributed to some unidentified deep magmatic body. Our field structural data document fracturing and faulting that affect both the reservoir and the seal units with dominant NE-SW and a subordinate E-W as maximum extension directions. The surface pattern and kinematics indicate that fault systems are part of the Pliocene-Quaternary tectonic episode in Central Italy, where strike-slip kinematics transfers deformation between main extensional shear zones. The fault network controls intense hydrothermal manifestations and travertine deposition north of the Torre Alfina area. 230Th/234U dating allows distinguishing three different stages of hydrothermal pulses bracketed between 200 and 90 ka. To improve the current understanding of the geometry and density of subsurface fracture system we applied the Shear Wave Splitting (SWS) technique studying the waveforms from local microearthquakes recorded in the area from 2008 to 2011. The analysis of SWS provides parameters directly related to the strike of the subsurface fluid-filled fractures and their density. According to the extensive-dilatancy anisotropy hypothesis (Crampin, 1984) SWS is generated by propagation through distributions of fluid-filled cracks, microcracks, and preferentially oriented pore space aligned according to the active stress field in the area. The analysis was made using the software ANISOMAT and gives a major direction NW-SE. The results agree both with structural data and with the focal mechanism of the earthquakes collected in the area between years 1977 and 1992. From the analysis on the crack density our data gives as result a good index of fracture for the reservoir’s rocks. Based on the updated conceptual model we performed numerical simulations in TOUGH2 code. Results indicate that deep circulation is forced by the geometry of the reservoir and by T and P gradients. We interpret the Torre Alfina field as a "blind" system, formed dominantly by lateral advection of heat and mass from the Bolsena caldera deep system driven both by high T and by the greater depth at which reservoir rocks are downthrown by the volcano-tectonic collapse. Preferential fracture fabric in the deep carbonates allows the lateral heat transfer. The cap-rocks have excellent sealing characteristics allowing the preservation of heat in correspondence with positive structural traps