Different Localities of Potassium-Rich Silica-Undersaturated Igneous Rocks and Their Silica-Rich Variants - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 178

Fig. 4.25 Sketch map of
Ischia complex. The dotted
line is the limit of the
volcanics younger than
10,000 year B.P. Symbol: GT
Grotta di Terra dyke;
V Valeliero; CN Cava
Nocelle; M Molara; RC Rio
Corbore; R Monte Rotaro
(after Girolamo et al. 1995)

Mt.Vico
Lacco Ameno

11 01

N

11 08
12SF
13SF

Ischia

R

Forio

Mt.Epomso

RC

11 06

11 05
11 03
11 02

M

11 04

11 09
GT

CN

S. Angela

0

5km

ISCHIA ISLAND

Arso erupted around 1302 A.D. The rocks are porphyritic with phenocrysts of
sanidine, green clinopyroxene, forsteritic olivine, chromian-rich spinel inclu-
sion, plagioclase, biotite and magnetite in a groundmass of alkali feldspar
displaying a trachytic texture.

Latites are observed at Cava Nocelle. The rocks have similar texture as those
erupted from Arso, but with relatively less amount of olivine and K-feldsar. Latites
of Vateliero are more ma c but contain relatively more plagioclase in the

groundmass.
The ma c inclusions in the rocks of Ischia represent the most primitive products

found so far in the Island, as they contain relatively lowest

87 Sr/ 86 Sr ratios

(0.70504) amongst the rocks of Roman province.

4.8.4.11 Mount Vulture Volcanic Complex

The volcanic complex of Mount Vulture (Lucania, Italy; Fig. 4.26 ) is the eastern most
complex of the Roman magmatic province. This complex is situated close to the
buried front, marking the overthrust of southern Apennine nappes on the Apulian
foreland (De Lorenzo 1980, Melluso et al. 1996). TheMt. Vulture complex is different
from other volcanic complexes of the Roman Province, which are located west of the
Apennine chain, far from the Apulian foreland. Mt. Vulture consists of several vol-
cano-clastic units and subordinate lava flows that together built up a strato volcano.

The volcanic activity started in the Middle Pleistocene (La Volpe et al. 1984) and was
active between 0.8 and 0.42 Ma (De Fino et al. 1986). The rocks of Mt. Vulture are
predominantly basanites to trachyphonolites. It is also the only complex, where
sodalite group of feldspathoids is more important than leucite.
The volcanic rocks, which were erupted yne-bearing trachy-phon-

olites and phono-tephritic products. They occur on the lower and outer

rst, are ha ü

flanks of the