Publikationsdatum:
2017-10-06
Beschreibung:
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.
Beschreibung:
Published
Beschreibung:
191-208
Beschreibung:
2.3. TTC - Laboratori di chimica e fisica delle rocce
Beschreibung:
JCR Journal
Beschreibung:
reserved
Schlagwort(e):
Pantellerites
;
Pantelleria
;
peralkaline magmatism
;
halite
;
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
Repository-Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Materialart:
article
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