Search results for "Experimental Petrology"

Experimental and thermodynamic constraints on mineral equilibrium inpantelleritic magmas

2020

Abstract Crystallization experiments on two pantellerites from Pantelleria, Italy, provide new evidence for the relationships between mineral phases in pantelleritic rocks as well as the influence of temperature and redox conditions on mineral assemblages. Experiments were performed at 1 kbar with temperature ranging between 750–900°C, and fluid saturation conditions with XH2O (=H2O/H2O+CO2) between 0 and 1. Redox conditions were fixed at, or slightly below, the FMQ buffer. Results show that at temperature of 900 °C pantelleritic magmas are well above the liquidus regardless their water content; we also observed a decrease in liquidus temperature (800°C) with increasingly reducing condition…

Low-P hydrous phase equilibria of a pantellerite melt: constraints on pre-eruptive conditions of recent felsic explosive volcanism at Pantelleria.

2007

Experimental investigation on peralkaline silicic magmas of Pantelleria Island: inferences on pre-eruptive conditions, magma evolution and water solu…

2017

Recent felsic explosive magmatism at Pantelleria island: an experimental study

2009

Experimental constraints on pre-eruptive conditions of a chemically-zoned peralkaline ignimbrite: the Green Tuff eruption at Pantelleria Island (Ital…

2015

Pantelleria island is the type locality for pantellerite, an iron and alkali-rich rhyolite. The eruptive products outcropping in the island fall in a mafic end member (mildly alkaline basalt) and a felsic end member (metaluminous trachytes and pantellerites). A key event in the volcanological history of the island is the Green Tuff eruption the sole ignimbrite at Pantelleria compositionally zoned from crystal-poor pantellerite at the base to crystal-rich trachyte at the top. We experimentally investigated the phase relations of the pantelleritic end member AI = 1.8 (agpaitic index = molar ratio Na2O+K2O/Al2O3) and trachyte end member AI = 1.05 of the Green Tuff eruption. The intensive varia…

PETROLOGICAL AND EXPERIMENTAL CONSTRAINTS ON THE PRE-ERUPTIVE CONDITIONS OF LA SOMMATA BASALT AND BROWN TUFFS TEPHRA (AEOLIAN ISLANDS)

2011

This work is focused on two key eruptions of Vulcano Island: 1) the most primitive magma of Vulcano erupted by the La Sommata scoria cone, a silica-undersaturated Ca-rich shoshonitic basalt with olivine-hosted primitive melt inclusions having an ultra-calcic character; 2) the most energetic eruptions of the whole Aeolian Archipelago, the Brown Tuffs (BT) eruptions, which produced several pyroclastic deposits, covering an ample age interval, spread out over a large portion of all Aeolian islands up to the northern coast of Sicily (Lucchi et al., 2008). By complementary studies of melt inclusions and experimental petrology, we pursued the following main objectives: (i) to constrain the pressu…

Experimental Constraints on the Deep Magma Feeding System at StromboliVolcano, Italy

2009

International audience; New experiments have been performed on a high-K basalt (PST-9) from Stromboli volcano, Italy, to constrain the physical conditions of golden pumice magmas at their storage level and discuss their petrogenesis. Fluid-present, H2O- and CO2-bearing, near-liquidus experiments were performed at 11508C between 100 and 400MPa and under oxidizing conditions. Glasses were analyzed by Fourier transform IR spectroscopy and their H2O and CO2 concentrations compared with those in glass inclusions.Most glass inclusions cluster near the 200MPa isobar, suggesting entrapment at a depth of ~8 km. Golden pumice magmas have viscosities of 7.9 Pa s and densities of 2.48-2.57 g/cm3. Compo…

Phase equilibria of Pantelleria trachytes (Italy): constraints on pre-eruptive conditions and on the metaluminous to peralkaline transition in silici…

2018

Pantelleria Island is the type locality of pantellerite, an iron and alkali-rich rhyolite (P.I=molar Na2O+K2O/Al2O3 >1.05). Peralkaline rhyolites (i.e pantellerite and comendite) and trachytes usually represent the felsic end-members in continental rift systems (e.g., Pantelleria, Tibesti, Ethiopia, Afar, Kenya, Bain and Range, South Greenland) and in oceanic sland settings (Socorro Is., Easter Is., Iceland and Azores). The origin of peralkaline rhyolites in the different tectonic settings is still a matter of debate and three hypotheses have been suggested: (a) crystal fractionation of alkali-basalt in a shallow reservoir to produce a trachyte which subsequently gives rise to a pantelle…

Pre-Eruptive Conditions of La Sommata Basalt (Vulcano, Aeolian Islands): Constraints from Experimental Petrology.

2011

One of the most primitive magma of Aeolian Arc is the basalt erupted (about 50 ka B.P.) by the La Sommata scoria cone at Vulcano; this is a silica-undersaturated (ne-normative) low-phyric (10-20 wt. %), Ca-rich (CaO = 13 wt. %) shoshonitic basalt (K2O = 2.28 wt.%) in which olivine phenocrysts host melt inclusions more primitive than whole rock composition and with an ultra-calcic character: CaO/Al2O3 > 1.4 [Métrich and Clocchiatti, 1996; Gioncada et al., 1998; Schiano et al., 2000]. Phenocrysts mainly include olivines (Fo92) and clinopyroxenes (Fs5). Plagioclase microlites (from An79 to An67) are the most abundant groundmass phase (45 wt. %), together with clinopyroxene (Fs11) and olivine (…