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Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/3402

Authors: Rotolo, S. G.*
La Felice, S.*
Mangalaviti, A.*
Landi, P.*
Title: Geology and petrochemistry of the recent (<25 ka) silicic volcanism at Pantelleria Island
Title of journal: Bollettino della Società Geologica Italiana
Series/Report no.: 2 / 126 (2007)
Publisher: Società Geologica Italiana
Issue Date: 2007
Keywords: Pantellerites
Pantelleria
peralkaline magmatism
halite
Abstract: Pantelleritic pumice fall on the northern slopes of M. Grande have 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.
Appears in Collections:04.08.05. Volcanic rocks
Papers Published / Papers in press

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