Publication Date:
2017-04-04
Description:
We report on the newly discovered lava flow that erupted in the Colli Albani Volcanic District, which is the
most recent and, geochemically the most peculiar effusive event recognised in the entire ultrapotassic
Roman Province (Central Italy).
This lava flow is associated with the Monte Due Torri scoria cone, located approximately 5 km south of the
Albano hydromagmatic centre (69–36 ka). TheMonte Due Torri scoria cone displays well-preserved morphological
characteristics and the 40±7 ka age determined for the associated lava flow indicates that its activity was
nearly contemporaneous to the most recent, explosive activity that occurred at the Albano centre from 41 to
36 ka.
By comparing chemical and petrological features of the Monte Due Torri lava flow, Albano products, and older
products (N69 ka), we show that the youngest Colli Albani eruptions were fed by two new batches of parental
magmas that originated in a phlogopite-bearing metasomatised mantle, each one feeding one of the two youngest
eruptive cycles (at 69 ka and 41–36 ka). The trace element signature, e.g., very low Pb content, of primitive
(MgON3 wt.%) magmas feeding the initiation of the hydromagmatic activity at Albano (69 ka) and the subsequent
effusive activity at Monte Due Torri (40 ka) indicates that a magma chamber located in the deep
anhydrite-bearing dolomite formation was tapped. However, the polygenic activity, the changes in magma
composition, and the variable thermometamorphic clasts occurring in the hydromagmatic deposits (recording
variable substrata) suggest, particularly for the Albano eruptive centre, a more complex plumbing system consisting
of at least two more magma chambers at a shallower depth, i.e., in the Mesozoic limestone and Pliocene
pelite formations.
The large amount of stratigraphic, volcanological, and geochemical data collected for the Colli Albani Volcanic
District, one of the main districts in the ultrapotassic Roman Province, enable us to contribute insights into the
still open debate regarding the temporal variation of the metasomatised mantle source of the Italian potassic
magmas. Based on our data, i.e., variation of radiogenic and trace elements over time, we suggest that the observed
variation in the mantle source of the ultrapotassic magmas can be related to progressive consumption
of the phlogopite component in the metasomatised source rather than the transition from lithosphere- to
asthenosphere-derived magmatism and/or the transition from orogenic to anorogenic magmatism.
Description:
Published
Description:
298-308
Description:
2.3. TTC - Laboratori di chimica e fisica delle rocce
Description:
JCR Journal
Description:
reserved
Keywords:
ultrapotassic magmas
;
metasomatised mantle
;
Roman Province
;
Colli Albani
;
04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Permalink
