Comment on “40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy): toward a new chronostratigraphic reconstruction of the Holocene volcanic activity” by Fedele et al. [Bull Volcanol; 73:1323–1336]

Reply to the comment on the article “40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy): toward a new chronostratigraphic reconstruction of the Holocene volcanic activity” by Isaia et al.

“…Epistemology of an untenable proposition and some stratigraphic remarks Isaia et al (2011) warn against contradicting "the(ir) actual stratigraphic framework" essentially based on data presented by Di Vito et al (1999). The commenting authors seem persuaded that an "actual stratigraphic framework" truly exists, corresponding with that reported in their previously published papers, and argue that the new age data of Fedele et al (2011) are "inconsistent" with this framework.…”

“…We thus did not consider data coming from distal sequences like those of Passariello et al (2010a, b), which report the occurrence of some Phlegrean deposits but do not offer proximal evidence supporting the proposed correlations. Similarly, clearly stated that stratigraphic relationships reported in the Isaia et al (2009) paper contain inconsistencies suggesting that there must have been problems with their 14 C or 40 Ar/ 39 Ar dating, as now Isaia et al (2011) implicitly admit suggesting for the Agnano-Monte Spina eruption an age of 4.482-4.625 ka, instead of the~4.1 ka reported in Isaia et al (2009).…”

“…We begin addressing the criticisms of Isaia et al (2011) regarding our age determinations and then we clarify our ideas about previous stratigraphic studies.…”

“…Demonstration of homogeneity can be by single-crystal work and/or by incremental heating [note that Fedele et al (2011) and Insinga et al (2006) employed incremental heating in a resistance furnace, not with a laser]. However, simply choosing the younger age determination does not guarantee reliable results, as implied by Isaia et al (2011). Excess argon, not xenocrystic contamination, yielded old apparent ages for the AD 79 eruption of Vesuvius in samples collected from the Villa of Poppea (Renne et al 1997), but not from the Casti Amanti site (Lanphere et al 2007).…”

“…Moreover, in a context in which all our new Ar/Ar data are rapidly discarded, it is revelatory that there are no comments on the rejuvenation of the Nisida volcano from the I to the III epoch. The stratigraphic consequences of this are left out by Isaia et al (2011) that, following their reference paper, should shift also the overlying deposits to the III epoch (Pignatiello 1, Concola, Fondo Riccio and Pisani 3) or simply accept that their stratigraphic framework contains inconsistencies.…”