GNGTS 2013 - Atti del 32° Convegno Nazionale

Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano, with a high speed PIXcel detector, Ni-filtered, CuKα radiation, at 40 kV and 40 mA in a 3-70 º2θ range, with 0.02º steps at 8 s/step. The samples were powdered in an agate mill immediately before analysis. Diffraction patterns were interpreted using the X’Pert HIGH Score Plus computer program. Feldspars and glass shards were leached with cold and warm 2.5 N HCl for 10 minutes, then rinsed several times in pure sub-boiling distilled water, and finally dissolved with high-purity HF–HNO 3 –HCl mixtures. Sr and Nd were separated by standard cation-exchange methods. Their isotope ratios were measured statically by Thermal Ionization Mass-Spectrometer (TIMS, ThermoFinnigan TM Triton TI) at the Istituto Nazionale di Geofisica e Vulcanologia, Sezione Osservatorio Vesuviano di Napoli and were corrected for mass fractionation using 86 Sr/ 88 Sr = 0.1194. Replicate analysis of NIST NBS 987 Reference Standard gave average values of 0.710192 ± 0.000017 (2 σ , n = 25); Sr blank was of the order of 0.1ng during the period of chemistry processing. The measurement of 143 Nd/ 144 Nd ratios is in progress. Very pure feldspar crystals from cores and from selected drilled strata were also prepared for 40 Ar/ 39 Ar dating for the results of which we are waiting. Drilling mud gas monitoring was carried out to gain new insights into the structure of the fluid regime at depth and to understand migration processes of deep circulating fluids. Gas was extracted mechanically from the circulating drilling mud in a separator tank equipped with a motor which drives an inside propeller. The separator was placed at the so-called “Possum Fig. 2 – Back-scattered electron images (core at 500 m): a) widespread hydrothermal alteration in argillitic phases; b) Illite/montimorillonite and glauconite plats grown in pumice pipes; c) dolomite in isolated cuspate grains; d) within rocks fractures. 266 GNGTS 2013 S essione 1.3