Publication Date:
2017-04-04
Description:
Despite its ultra-potassic, basic geochemistry (40≤SiO2≤50 wt.%), the Alban Hills Volcanic District was
characterized by a highly explosive phase of activity, the Tuscolano–Artemisio phase, which emplaced very
large volumes (several tens of km3 each cycle) of pyroclastic-flow deposits, mafic in composition
(SiO2≤45 wt.%) in the time span 600–350 ka. In contrast to the abundance of pyroclastic-flow deposits,
very scarce basal Plinian deposits and, more in general, fallout deposits are associated to these products.
While some of the pyroclastic-flow deposits have been described in previous literature, no specific work on
the Tuscolano–Artemisio phase of activity has been published so far. In particular, very little is known on the
products of the early stages, as well as of the final, post-caldera activity of each eruptive cycle. Here we
present a comprehensive stratigraphic and geochronologic study of the Tuscolano–Artemisio phase of
activity, along with new textural and petrographic data. We describe the detailed stratigraphy and
petrography of five reference sections, where the most complete suites of products of the eruptive cycles,
comprising the initial through the final stages, are exposed.We assess the geochronology of these sections by
means of 18 new 40Ar/39Ar age determinations, integrating them with 16 previously performed, aimed to
describe the eruptive behavior of the Alban Hills Volcanic District during this phase of activity, and to assess
the recurrence time and the duration of the dormancies.
The overall explosive activity appears to be strictly clustered in five eruptive cycles, fairly regularly spaced in
time and separated by very long dormancies, in the order of several ten of kyr, during which no volumetrically
appreciable eruption occurred, as the lack of deposits dated to this time-interval testify.We propose a volcanotectonic
model that explains this peculiar eruptive behavior, unparalleled in the other coeval volcanic districts
of the Tyrrhenian margin of Italy, as related to the local transpressive tectonic regime.
Description:
Published
Description:
217-232
Description:
3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
Description:
JCR Journal
Description:
reserved
Keywords:
Alban Hills 40Ar/39Ar geochronology explosive eruptions K-alkaline magmas pyroclastic-flow deposits volcanotectonics
;
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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