The Valle del Bove is a horse-shoe shaped depression, 8km long and 5km wide, cut into the eastern flanks of Mount Etna, Sicily. In the southern cliff walls there are exposed the lavas and pyroclastics erupted by six ancient centres of activity which existed in the vicinity of the site now occupied by the Valle del Bove. The majority of these volcanics originated at a centre, Trifoglietto II, which occupied a position on the site of the southern Valle del Bove, and which was still erupting lavas at 25,000 ys BP. A reconstruction of the topography which previously existed within the Valle del Bove, is accomplished by extrapolating preserved contours on the northern and southern walls of the depression. Reconstruction of the Trifoglietto II centre shows that its summit was probably between 2500m and 2600m above present sea-level, and that it consisted of a cone constructed predominantly from pyroclastic materials, overlain on its southern and eastern flanks by lavas. A stratigraphy is constructed for the southern wall. The Trifoglietto II lavas rest unconformably upon the eroded remnants of an older centre, and are themselves overlain by the products of younger centres. All the lavas exposed in the southern wall are of alkalic affinity, and comprise a trachybasaltic suite ranging from hawaiite to benmoreite. Variation in the chemistry of most of the lavas can be explained by their differentiation at high levels in the crust, from a more basic magma of alkalibasalt/hawaiite composition. Chemical variation in the Trifoglietto II lavas, however, can best be explained as a result of generation by the partial melting of garnet-peridotite material at upper mantle depths and pressures. A study has been made of the numerous dykes exposed in the walls of the Valle del Bove., the alignments of which parallel trends which are important on Etna at the present time. It is proposed that the Valle del Bove was formed by phreatic or phreato-magmatic eruptions which destroyed the Trifoglietto II centre, some 15-17,000 ys BP, following magmatic extinction at the centre. The eruptions produced lahars which are evident to the east of the depression, and extensive air-fall ashes. Subsequent enlargement of the Valle del Bove was accomplished by fluvial erosion.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:678861 |
| Date | January 1980 |
| Creators | McGuire, William Joseph |
| Publisher | University of Bedfordshire |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10547/593084 |
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