Publication Date:
2017-04-04
Description:
A continuous-coring borehole recently drilled at Camaldoli dellaTorre
on the southern slopes of Somma^Vesuvius provides constraints on the
volcanic and magmatic history of the Vesuvian volcanic area since
c. 126 ka BP. The cored sequence includes volcanic units, defined on
stratigraphical, sedimentological, petrological and geochemical
grounds, emitted from both local and distal vents. Some of these units
are of known age, such as one Phlegraean pre-Campanian Ignimbrite,
Campanian Ignimbrite (39 ka), Neapolitan Yellow Tuff (14 9ka) and Vesuvian Plinian deposits, which helps to constrain the relative
age of the other units.The main rock types encountered are shoshonite,
phonotephrite, latite, trachyte and phonolite. The sequence includes,
from the base upwards: a thick succession of pyroclastic units emplaced
between 126 and 39 ka, most of them attributed to eruptions that
occurred in the Phlegraean area; the Campanian Ignimbrite; the
products of a local tuff cone formed between 39 ka and the deposition
of the products of the earliest activity of the Mt. Somma volcano; the
products of the Somma^Vesuvius volcano, which include from the base
upwards a thick sequence of lavas, pyroclastic rocks and the products of
a local spattercone dated between 3 7ka and AD 79.The data obtained from the study of the borehole show that, before the Campanian
Ignimbrite eruption, low-energy explosive volcanism took place in
the Vesuvian area, whereas mostly high-energy explosive eruptions
characterized the Campi Flegrei activity. In the Vesuvian area,
Campanian Ignimbrite deposition was followed by the eruption of
a local tuff cone and a long repose time, which predated the formation
of the Mt. Somma edifice. Since 18 3 ka (Pomici di Base eruption) the activity of Somma^Vesuvius became mostly explosive with rare
lava effusions.The shallowest cored deposits belong to the Camaldoli
dellaTorre cone, formed between the Pomici di Avellino and Pomici di
Pompei eruptions (3 7 ka^AD 79). Newgeochemical and Sr^Nd^Pb^ B-isotopic data on samples from the drilled core, together with those
available from the literature, allow us to further distinguish the
volcanic rocks as a function of both their provenance (i.e. Phlegraean
or Vesuvian areas) and age, and to identify different magmatic
processes acting through time in the Vesuvian mantle source(s) and
during magma ascent towards the surface. Isotopically distinct
magmas, rising from a mantle source variably contaminated by slab-
derived components, stagnated at mid-crustal depths (8^10 km
below sea level) where magmas differentiated and were probably
contaminated. Contamination occurred either with Hercynian
continental crust, mostly during the oldest stages of Vesuvian activity
(from 39 to 16 ka), or with Mesozoic limestone, mostly during recent
Vesuvian activity. Energy constrained assimilation and fractional
crystallization (EC-AFC) modelling results show that contamina-
tion with Hercynian crust probably occurred during differentiation
from shoshonite to latite. Contamination with limestone, which is not
well constrained with the available data, might have occurred only
during the transition from shoshonite to tephrite. From the ‘deep’
reservoir, magmas rose towards a series of shallow reservoirs, in which
they differentiated further, mixed, and fed volcanic activity.
Description:
Published
Description:
753-784
Description:
2.3. TTC - Laboratori di chimica e fisica delle rocce
Description:
3.5. Geologia e storia dei sistemi vulcanici
Description:
JCR Journal
Description:
reserved
Keywords:
Somma^Vesuvius
;
crustal contamination
;
source heterogeneity
;
radiogenic and stable isotopes
;
04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
;
04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
;
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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