The island of Pantelleria is located in the Pantelleria Rift between Sicily and Africa. This rift is floored by a 20 km thick continental-type crust that is characterized by horsts and grabens formed by NW-SE tensional faults and NE-SW shear faults. Several faults and fractures that intersect the island follow these regional trends. Prominent volcano-tectonic features on the island include two calderas, the younger being related to the eruption of the green ignimbrite and the uplifted Montagna Grande block. Pantelleria mostly consists of peralkaline silicic rocks with minor trachytes and basalts. Volcanism on the island is characterized by both explosive and effusive activity. Reconstruction of the volcanic history of the island since the eruption of the green ignimbrite is based on geological and geochronological data. The eruption of the green ignimbrite (50,000 y.b.p.) was followed by collapse of the Monastero caldera that has been the site of most of the subsequent acid volcanism. The Montagna Grande volcanic complex (35,000 y.b.p.) fills the central part while the lower pantelleritic lava flows (16,000 y.b.p.) erupted along its rim. Very probably the young Mt. Gelfiser and Khaggiar domes are also located on the caldera rim. The Montagna Grande block rose within the caldera at an estimated average rate between 1.0 and 1.5 cm/y for about 20,000 y. Subsequent pumice cones (9,000 y.b.p.), endogenous domes, and lava flows also erupted inside this caldera. Among the main acid volcanic units younger than the green ignimbrite, only the Mt. Gelkhamar endogenous dome is not linked to this caldera. In the last 50,000 years basaltic activity only occurred in the northern part of the island. The basaltic vents are aligned parallel with the main tensional trends of the rift. At least two phases have been recognized; the older is about 29,000 y.b.p. and the younger is a few thousands of years old. A change occurred in the eruptive style after the eruption of the green ignimbrite and collapse of the Monastero caldera. Explosive activity diminished and extrusion of lava became dominant. © 1983.
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|Titolo:||Recent volcanic history of pantelleria: A new interpretation|
|Data di pubblicazione:||1983|
|Appare nelle tipologie:||1.1 Articolo in rivista|