Paleozoic metasomatism at the origin of Mediterranean ultrapotassic magmas: Constraints from time-dependent geochemistry of Colli Albani volcanic products (Central Italy)

Assessing the volcanic hazard for Rome: 40Ar/39Ar and In‐SAR constraints on the most recent eruptive activity and present‐day uplift at Colli Albani Volcanic District

“…Indeed, part of the hydromagmatic centers previously attributed to the recent activity phase has been shown to be instead part of the older TA and MdF phases [Gaeta et al, 2016]. Indeed, part of the hydromagmatic centers previously attributed to the recent activity phase has been shown to be instead part of the older TA and MdF phases [Gaeta et al, 2016].…”

“…Assessing the eruption ages for several of ephemeral centers can be problematic, since xenocrystic contamination in hydromagmatic products, in which the juvenile fraction may be reduced or even lacking, is a common occurrence. Prata Porci (previously assessed age ≤279 ± 6 ka [Gaeta et al, 2016]); Pantano Secco (previously assessed age 364 ± 2 ka [Marra et al, 2003]); Valle Marciana (previously assessed age 365 ± 2 ka [Marra et al, 2003]); Giuturna (previously assessed age ≤72 ± 2 ka [Marra et al, 2003]); and Monte Savello (previously undated). Bearing in mind these potential problems, we have conducted new sampling of the volcanic centers yielding stratigraphically inconsistent or doubtful age results in previous studies.…”

“…In addition, in order to obtain indirect chronological constrains, based on the time-dependent trends of 87 Sr/ 86 Sr and 143 Nd/ 144 Nd analysis [e.g., Gaeta et al, 2006;Giaccio et al, 2013], we also present previously unpublished Sr and Nd isotope ratios performed by Gaeta et al [2016; see methods in this paper], for the Santa Fumia lava flow (AH37; Figure 1a), cropping out on the western flanks of the Giuturna crater rim, whose temporal relationship with the hydromagmatic activity of this maar was previously not firmly established.…”

“…The southeastern suburbs of the City of Rome extend onto the gentle slopes of the Colli Albani Volcanic District (CAVD), the eruptive history of which spans between 608 ka and 36 ka [Karner and Renne, 1998;Karner et al, 2001a;Marra et al, 2003;Freda et al, 2006;Giaccio et al, 2009;Marra et al, 2009;Gaeta et al, 2011Gaeta et al, , 2016. This relies on the knowledge of a number of volcanological processes and physical parameters including the eruptive history (e.g., styles of eruptive events and their time recurrence) and the current surface deformations, all of which are of paramount importance.…”

“…This relies on the knowledge of a number of volcanological processes and physical parameters including the eruptive history (e.g., styles of eruptive events and their time recurrence) and the current surface deformations, all of which are of paramount importance. More recently, based on an updated geochronological data set [Gaeta et al, 2016], the weighted average recurrence period for these eruptive cycles has been better constrained to 44.6 ± 1.5 kyr, along with the weighted average dormancy of 38.8 ± 1.5 kyr, defined as the time elapsed between the end of an eruptive cycle and the start of the successive one. The almost regular temporal recurrence of~45 kyr (periodicity coefficient Cv = 0.38) for the 11 eruptive periods during the whole CAVD history allowed in the past to asses a quasi-cyclical eruptive behavior [Marra et al, 2004a].…”