GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 1.1 141 Fig. 1 – Examples of investigated and fingerprinted-correlated tephra occurring in alluvial-fluvial-lacustrine successions of central-southern Italy. robust and effective tephra correlation comprise: i) trace element data acquired by Laser Ablation Inductively Couple Plasma Mass Spectrometry, ii) Sr-Nd isotope analyses of glass and/or mineral phases and iii) major and trace elemental analyses of mineral phases. However, all these analyses provide indications for an indirect dating of tephra, as we assign to each tephra the age of an eruptive unit dated elsewhere (e.g. in proximal volcanic or distal setting) via geochemical correlation. In turn, the recent development of the sensitivity of last generations mass spectrometers allows the direct dating of tephra by 40 Ar/ 39 Ar single crystal fusion method. This dating method can be successfully applied on very fine-grained K-rich crystals, with a high accuracy, precision and reproducibility. As matter of fact, its application on distal setting, combined with geochemical and isotope analyses, is becoming a routine and indispensable procedure (e.g. Giaccio et al. , 2012, 2013, 2014, 2015; Iorio et al. , 2014;