Large mafic eruptions at Alban Hills Volcanic District (Central Italy): Chronostratigraphy, petrography and eruptive behavior

CO2-driven large mafic explosive eruptions: the Pozzolane Rosse case study from the Colli Albani Volcanic District (Italy)

“…Despite the rather uniform magma composition, volcanic activity (~608-36 ka, Marra et al 2003Marra et al , 2009, and references therein) encompassed a wide spectrum of eruption styles, intensities and magnitudes, ranging from effusive to mildly explosive (strombolian and hydromagmatic) to large pyroclastic-flow-and caldera-forming events. Colli Albani volcanism was traditionally subdivided into three main periods of activity (e.g.…”

“…Two eruptive periods, characterised by different eruptive behaviours, have been recognised (Marra et al 2009), with two pyroclastic current deposit end-members associated; these are volumetrically dominant over co-eruptive scoria fallout from sustained column phases (de Rita et al 1995;Trigila et al 1995;Freda et al 1997;Palladino et al 2001;Watkins et al 2002): (1) well-stratified, accretionary-lapilli-bearing ash deposits, driven by explosive magma-water interaction (early Tuscolano-Artemisio eruptive phase; 561-527 ka; Marra et al 2009); (2) massive, coarse deposits bearing scoria lapilli and blocks (instead of true pumices), which show no evidence of hydromagmatic fragmentation (late Tuscolano-Artemisio eruptive phase; 456-366 ka; Marra et al 2009), including those known locally as "pozzolane", e. g. Pozzolane Nere, Villa Senni upper flow unit and the Pozzolane Rosse, which we deal with in this paper.…”

“…On the other hand, the local decompression along NE-striking fractures associated with this stress field, as well as that induced by crustal blockrotation along the N-S strike-slip faults, capable of tapping magma chambers at depth, may have triggered voluminous lava effusions from peripheral vent systems (e.g. the Vallerano lava flow, Marra et al 2009, at the onset of the PR eruption, see below).…”

“…3. According to the most recent 40 Ar/ 39 Ar ages (Marra et al 2009), the PR eruptive event (II Tuscolano-Artemisio pyroclastic-flow unit, de Rita et al 1988aRita et al , 1995Giordano and Dobran 1994;Corcolle Eruption Unit, Trigila et al 1995) occurred at 456±3 ka. The emplacement of the PR pyroclastic units was preceded by the effusion of a lava plateau (2-3 km 3 in volume) from a peripheral vent system (Vallerano lava flow; 457±5 ka, Marra et al 2009), which, based on the lack of intervening stratigraphic discontinuities in the deposits and comparable radiometric ages, is regarded as part of the PR eruptive cycle.…”

Analysis of the Seismic Site Effects along the Ancient Via Laurentina (Rome)

“…The aggradational successions near Rome therefore represent a discontinuous stratigraphic record that is composed of a succession of ten major aggradational units that were deposited during MIS 22-21 thorough MIS 2-1 and several minor successions that correspond to the more pronounced sub-stages and represent the physical remnants of the glacio-eustatic sea-level cycles during this time period. These successions fill the fluvial valleys and the coastal plain incisions that were excavated during the sea-level lowstands and interfinger with the pyroclastic products of the Colli Albani and Monti Sabatini Volcanic Districts, whose activity spanned 600-20 ka [Marra et al 2009[Marra et al , 2014; [Gaeta et al 2016 and references therein]. A thick succession of pyroclastic flow deposits and subordinate air-fall deposits interfingers with the continental sediments that were deposited within palaeovalleys during periods of sea-level rise, which caused significant lateral and vertical facies variability.…”