Options
Gozzi, Fernando
Loading...
3 results
Now showing 1 - 3 of 3
- PublicationRestrictedPetrology of the most recent ultrapotassic magmas from the Roman Province (Central Italy)(2011)
; ; ; ; ; ; ; ; ;Gaeta, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Freda, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Marra, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Rocco, T.; Sapienza Università Roma ;Gozzi, F.; Sapienza Università Roma ;Arienzo, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Giaccio, B.; IGG-CNR ;Scarlato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; 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.328 22 - PublicationRestrictedPrimary magmatic calcite reveals origin from crustal carbonate(2014)
; ; ; ; ; ; ; ; ;Gozzi, F.; Università Sapienza ;Gaeta, M.; Università Sapienza ;Freda, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Mollo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Rocco, T.; Georg August Universität ;Marra, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Dallai, L.; CNR ;Pack, A.; Georg August Universität; ; ; ; ; ; ; Wehave investigated lava flows representative of thewhole eruptive history of the Colli Albani ultrapotassic volcanic district (Central Italy). One of the most intriguing features concerning some of these lava flows is the occurrence of primary, magmatic calcite in the groundmass. The primary, magmatic nature of calcite has been inferred by microtextural investigations showing that it typically occurs i) interstitially, associated with clinopyroxene, nepheline and phlogopite, ii) in spherical ocelli, associated with nepheline, fluorite and tangentially arranged clinopyroxene, and iii) in corona-like reaction zones around K-feldspar xenocrysts. These microtextural features distinctly indicate that calcite crystallized froma carbonate melt in a partially molten groundmass, implying that the temperature of the system was above the solidus of the hosted lava flow (N850 °C). Geochemical features of calcite crystals (i.e., stable isotope values and trace element patterns) corroborate their primary nature and give insights into the origin of the parental carbonate melt. The trace element patterns testify to a high-temperature crystallization process (not hydrothermal) involving a carbonate melt coexisting with a silicate melt. The high δ18O (around 27‰SMOW) andwide δ13C (−18 to+5‰PDB) values measured in the calcites preclude a mantle origin, but are consistent with an origin in the crust. In this framework, the crystallization of calcite can be linked to the interaction between magmas and carbonate-bearing wall rocks and, in particular, to the entrapment of solid and/or molten carbonate in the silicate magma. The stability of carbonate melt at lowpressure and the consequent crystallization of calcite in the lava flow groundmass are ensured by the documented, high activity of fluorine in the studied system and by the limited ability of silicate and carbonate melts to mix at syn-eruptive time scales.300 49 - PublicationRestrictedPaleozoic metasomatism at the origin of Mediterranean ultrapotassic magmas: Constraints from time-dependent geochemistry of Colli Albani volcanic products (Central Italy)(2016)
; ; ; ; ; ; ; ; ; ; ; ; ; The major processes that control the genesis of potassic volcanic rocks, like the timing of multi-stage mantle metasomatism, remain largely unclear. In an attempt to clarify the timing of the metasomatic process, a detailed geochronologic and geochemical study has been conducted on the ultrapotassic rocks of the Colli Albani Volcanic District (Central Italy). New 40Ar/39Ar data coupled with literature and newly performed 87Sr/86Sr, 143Nd/144Nd and chemical data allow us to precisely delineate the time-dependent geochemical variations of the magmas erupted at the Colli Albani Volcanic District and to better define mantle source processes responsible for their genesis. The temporal geochemical variations observed in the Colli Albani magmas indicate that: i) the ultrapotassic magmas originated from a metasomatized mantle source in which phlogopite is the potassium-bearing phase; ii) the partial melting of the mantle source involved mainly phlogopite and clinopyroxene (±olivine), whereas the role of accessory phases was less significant; and iii) the metasomatic process that led to the formation of the phlogopite in the mantle can be reasonably related to events that have occurred during the Paleozoic Era88 1