built a complex sequence of interfingered deposits emitted by closely spaced eruptive vents which are frequently associated with dome-building phases and pantelleritic lavas flows. Field relationships allowed us to recognize eight eruptive units, all lying above the Montagna Grande trachytes. As a whole, petrochemical characteristics of the erupted products indicate an evolutionary trend in which Na-clinopyroxene was the liquidus phase, followed by alkali feldspar. Amphibole and quartz are late-crystallizing, whereas aenigmatite is both early- and late-crystallizing as well. Aenigmatite and Na-clinopyroxene crystallization buffers efficiently the increase of agpaicity, induced by feldspar crystallization, to values of agpaitic index <2.0. Some eruptions are characterized by distinctive mineral assemblages: the couple amphibole + aegirine occurs in the Fastuca tephra, whilst the fayalite + ilmenite + quartz association characterizes the Randazzo tephra. The Fastuca eruption, the most powerful among those studied, tapped a reservoir characterized by lower temperature and highly reducing conditions in comparison with the other eruptions. The frequent coexistence of Na-rich and Na-poor pyroxenes, may result from syn-eruptive mixing among variably evolved pantelleritic magmas. The occurrence of late-precipitated halite witnesses the exsolution of a Cl-rich brine during magma ascent.

ROTOLO SG, LA FELICE S, MANGALAVITI A, LANDI P (2007). Geology and petrochemistry of recent (25 ka) silicic volcanism at Pantelleria Island. BOLLETTINO DELLA SOCIETÀ GEOLOGICA ITALIANA, 126/2(126), 191-208.

Geology and petrochemistry of recent (25 ka) silicic volcanism at Pantelleria Island

ROTOLO, Silvio Giuseppe;LA FELICE, Sonia;
2007-01-01

Abstract

built a complex sequence of interfingered deposits emitted by closely spaced eruptive vents which are frequently associated with dome-building phases and pantelleritic lavas flows. Field relationships allowed us to recognize eight eruptive units, all lying above the Montagna Grande trachytes. As a whole, petrochemical characteristics of the erupted products indicate an evolutionary trend in which Na-clinopyroxene was the liquidus phase, followed by alkali feldspar. Amphibole and quartz are late-crystallizing, whereas aenigmatite is both early- and late-crystallizing as well. Aenigmatite and Na-clinopyroxene crystallization buffers efficiently the increase of agpaicity, induced by feldspar crystallization, to values of agpaitic index <2.0. Some eruptions are characterized by distinctive mineral assemblages: the couple amphibole + aegirine occurs in the Fastuca tephra, whilst the fayalite + ilmenite + quartz association characterizes the Randazzo tephra. The Fastuca eruption, the most powerful among those studied, tapped a reservoir characterized by lower temperature and highly reducing conditions in comparison with the other eruptions. The frequent coexistence of Na-rich and Na-poor pyroxenes, may result from syn-eruptive mixing among variably evolved pantelleritic magmas. The occurrence of late-precipitated halite witnesses the exsolution of a Cl-rich brine during magma ascent.
2007
Settore GEO/07 - Petrologia E Petrografia
ROTOLO SG, LA FELICE S, MANGALAVITI A, LANDI P (2007). Geology and petrochemistry of recent (25 ka) silicic volcanism at Pantelleria Island. BOLLETTINO DELLA SOCIETÀ GEOLOGICA ITALIANA, 126/2(126), 191-208.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/10941
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