Tuscan Magmatic Province

• Tuscan Magmatic Province
• Gavorrano Granite
• Montecatini Lamproite
• Orciatico Lamproite
• Radicofani Volcano
• Roccastrada Rhyolites
• S.Vincenzo Rhyolites
• Sisco Lamproite

Intra Appennine Province

• Intra Appennine Province
• Cupaello
• San Venanzo
Venanzite
Melilitolite

Roman Magmatic Province

• Roman Magmatic Province
• Alban Hills
• Vulsini

Ernici-Roccamonfina Magmatic Province

• Roccamonfina

Mount Vulture Province

• Mount Vulture
• Alvikites (carbonatite)
• Melilitite
• Haüynophyre
• Tephrite

Sicily Magmatic Province

• Sicily Magmatic Province
• Etna
• Iblei
• Ustica

Aeolian Arc

• The Aeolian Arc
• Alicudi
• Lipari
• Vulcano

other sections will be added soon

Ustica

location of the island of Ustica

The Island of Ustica is located in the southern Tyrrhenian Sea about 60 km north of the Sicily coast. The island represents the summit of a wide submerged complex, which rises more than 2000 m above the sea floor and reaches an altitude of 244 above sea level. Southeast of Ustica, a submarine mugearitic lava field (Prometeo) has been recently discovered, and data indicate a close compositional affinity with Ustica.

The island is strongly affected by tectonism and erosion. Ustica shows evidence of at least five relative sea-level stands, with marine terrces located at elevations from 5 m to 120 m above sea level, and ages ranging from 350 ka to 80 ka.

Structural and stratigraphic studies have shown that the exposed volcanism developed between 750 and 130 ka. The activity occurred below sea level until about 500 ka and consists of pillow lavas and pillow breccias presently exposed along the southern border of the island. Successively, both effusive and explosive activity took place, the latter being mainly related to water-magma interaction during eruption. The best preserved hydrovolcanic tuff cone is the Capo Falconiera centre, sited on the eastern tip of the island, where steep erosion cliffs expose a section of this centre. The magmatism has been predominantly mafic, with a single trachytic eruption and dome emplacement at about 424 ka.

The Ustica rocks range from mildly Na-alkaline basalt to trachyte on the TAS classification diagram, with a gap in intermediate compositions between about 55-60 wt % SiO2. The mafic rocks straddle the boundary between the subalkaline and the alkaline fields, displaying a transitional to mildly alkaline affinity. Textures of mafic rocks are variably porphyritic with phenocrysts of plagioclase and olivine and sporadic clinopyroxene. Fe-Ti oxides are generally found as microphenocrysts in the most differentiated rocks. Plagioclase crystals are generally weakly zoned. Olivine is the most abundant mafic phase. Clinopyroxene ranges from diopside to salite. Trachytic pumices contain a few phenocrysts of alkali feldspar, plagioclase and a few biotite and Fe-Ti oxides set in a vesicular glassy matrix.

Bibliography

• Peccerillo. A. Plio-Quaternary Volcanism in Italy. (2005)

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Basalt

Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)
Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)
Skeletal olivine crystals. XPL image, 10x (Field of view = 2mm)	Skeletal olivine crystals. XPL image, 10x (Field of view = 2mm)	Skeletal olivine crystals. XPL image, 10x (Field of view = 2mm)
Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)
Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)
Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine (partially altered by Iddingsite) and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)
Sieve texture in plagioclase and pyroxene crystals in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Sieve texture in plagioclase and pyroxene crystals in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Embayed (Resorbed) olivine in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)
Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)
Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. PPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)
Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)	Olivine and Plagioclase in a Basalt from Ustica. XPL image, 2x (Field of view = 7mm)

Hyaloclastite

Pale brown glass fragment, rimmbed by yellow palagonite. PPL image, 2x (Field of view = 7mm)	Pale brown glass fragment, rimmbed by yellow palagonite. Volcanic xelolith in balck. PPL image, 2x (Field of view = 7mm)	Pale brown glass fragment, rimmbed by yellow palagonite. Volcanic xelolith in balck. PPL image, 2x (Field of view = 7mm)
Pale brown glass fragment, rimmbed by yellow palagonite. PPL image, 2x (Field of view = 7mm)	Pale brown glass fragment, rimmbed by yellow palagonite. PPL image, 2x (Field of view = 7mm)	Pale brown glass fragment, rimmbed by yellow palagonite. PPL image, 2x (Field of view = 7mm)
Glass fragment altered by yellow palagonite. PPL image, 10x (Field of view = 2mm)	Glass fragment altered by yellow palagonite. PPL image, 10x (Field of view = 2mm)	Pale brown glass fragment, rimmbed by yellow palagonite. PPL image, 10x (Field of view = 2mm)
Glass fragment altered by yellow palagonite. There is also a small xenolith with green spinel. PPL image, 10x (Field of view = 2mm)	Glass fragment altered by yellow palagonite. PPL image, 10x (Field of view = 2mm)	Glass fragment altered by yellow palagonite. PPL image, 10x (Field of view = 2mm)

Trachyte

Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)	Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)	Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)
Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)	Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)	Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)
Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)	Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)	Plagioclase crystals in a Trachyte. XPL image, 2x (Field of view = 7mm)