CRYSTAL-CHEMISTRY OF CLINOPYROXENES FROM FILICUDI AND SALINA (AEOLIAN ISLANDS, ITALY) - GEOTHERMOMETRY AND BAROMETRY

Single clinopyroxene crystals from calc-alkaline volcanic rocks of Filicudi and Salina (Aeolian Islands, Italy) have been studied by X-ray diffraction and microprobe techniques to examine the relations between clinopyroxene crystal chemistry and the petrological features of the host rocks. The clinopyroxenes of Filicudi and Salina are chemically quite similar, but two different groups can be distinguished, diopsides and augites, often coexisting in the same rock. The Filicudi clinopyroxenes are generally characterized by a smaller cell volume and a more closely-packed structure; comparison with crystals from different environments suggests a higher pressure of crystallization for the Filicudi rocks. A relationship between SiO2 content of magma and clinopyroxene intracrystalline equilibration temperature is discussed in terms of different cooling history due to the more pronounced explosive character of the more silicic magmas, leading to more rapid quenching of eruption products. For a given rock-type, clinopyroxene equilibration temperature is also a function of sample position in the volcanic sequence, to which different cooling rates can be assigned

COOLING HISTORY OF A DYKE ON ALICUDI (AEOLIAN ISLANDS) FROM INTRACRYSTALLINE FE-2+-MG EXCHANGE-REACTION IN CLINOPYROXENE

Seven rock samples were collected from the cross-section of a 2.8-m-thick andesitic dyke on Alicudi (Aeolian Islands, Sicily). Thin section microprobe analysis of phenocrysts (pyroxenes, olivine and plagioclase) and whole-rock X-ray fluorescence show that samples at the chilled margins are sharply distinct, with the highest Mg, Cr and Ni contents. Seven single crystals of clinopyroxene were analysed by microprobe techniques, while their structures were refined using the X-ray diffraction method; different Mg-Fe2+ ordering in the M2 and M1 sites of clinopyroxene were observed across the dyke section. The equilibration temperature, evaluated by applying the geothermometer proposed by Molin & Zanazzi (1991), gives the highest values at the dyke margins (850-degrees-C) and the lowest values close to the middle (630-degrees-C). By applying the theoretical model of Jaeger (1968) for the cooling of volcanic bodies, as well as the Kudo & Weill (1970) plagioclase-liquid geothermometer (modified by Mathez, 1973), it was possible to calculate the cooling rates across the dyke section: from 8 and 34-degrees-C/h near the boundaries to 1-degrees-C/h in the middle

Rockfall Risk Assessment and Management Along the \u201cVia dell\u2019Amore\u201d (Lovers\u2019 Lane) in the Cinque Terre National Park (Italy)

The Via dell\u2019Amore (Lovers\u2019 Lane) is a 1 km long coastal path linking Manarola with Riomaggiore, the two eastern villages at the \u201cCinque Terre\u201d. Realized at the start of the nineteenth century as a service road for the modernization of the railway, it\u2019s now considered as one of the highlights of the Cinque Terre National Park. The trail has been historically affected by rockfall phenomena: the bedrock is made up of heterogeneous rock masses; blocks diameter ranges from 0.5 to 2 m, determining high speed values during their fall. The probability of a fatal event to occur is high, as recently proved by the four Australian women injured in September 2012: this occurrence caused the closure of the trail up to the present. The actual risk level is not acceptable, taking in consideration also the elevated vulnerability values. The main goal is to decrease both rockfall hazard and vulnerability: in the first place, through passive slope protection methods such as rockfall shelters and protecting wire meshes; in the second instance, through an early warning system connected to the civil protection corp and an environmental education program involving tourists and inhabitants