M. Loddo

Application of gravity and deep dipole geoelectrics in the volcanic area of Mt. Etna (Sicily)

Abstract The structural pattern of the basement of the Mt. Etna volcano is studied by combining results from new gravity and deep dipole geoelectric field data. At first, the Bouguer map was separated into regional and residual contour maps by a 50 km cut-off wavelength. Then, by the geoelectric interpretation, N-S and E-W resistivity cross-sections were elaborated, which were used as guidelines for modelling gravity residuals. After observing a close correspondence between Bouguer anomalies and resistivity classes, by a trial-and-error adjustment to the relationship between resistivity and density, a 3-D block model of the basement was finally constructed, which consistently matched with both gravity and geoelectric information content. Two main conclusions emerged from the combined interpretation. The first is the presence of diffuse inhomogeneities in the upper portion of the basement, down to an average depth of 2 km below sea level, in contrast with the regularity of the explored underlying portion. The second is the absence of geophysical markers suggesting the existence of a large magmatic chamber, down to about 3 km below sea level.

The tyrrhenian and pannonian basins: A comparison of two mediterranean interarc basins

Abstract A comparison of the geological and geophysical features of the Tyrrhenian and Pannonian basins shows that both are interarc basins; the former ensimatic and the latter ensialic. They are characterized by postorogenic, tectonically unaffected sediments, strong volcanic activity, anomalous upper mantle and heat flow. Taking into consideration the similarities and dissimilarities, the authors suggest that the tectogenetic evolution schemes proposed by Scholz et al. (1971), Karig (1971), Boccaletti and Guazzone (1972) and Stegena et al. (1975) for interarc basins are applicable for both basins. The Pannonian basin has finished its evolution in a less mature stage while the Tyrrhenian basin has been developing into an ensimatic interarc basin.

Thermal conductivity, diffusivity and specific heat variation of some Travale field (Tuscany) rocks versus temperature

Abstract Thermal parameters of eight rock samples (limestone, calcareous dolomite, quartzite, micaceous quartzite, phyllite, micaceous schistose quartzite, plagioclasic micaschists, gneiss) have been measured by the transient state cut-core method at temperatures ranging from 20° to 250°C. An average 22% decrease for the conductivity, 34% decrease for the diffusivity, and 19% increase for the specific heat have been observed. From a geothermal point of view (heat extraction from hot dry rocks) the most promising rocks are micaschists whose specific heat varies between 1.48 · 103 J kg−1 K−1 at 20°C and 1.62·103J kg−1 K−1 at 220° C.

Heat-flow measurements on the Northern Apennine arc

Abstract Temperature and thermal-conductivity measurements have been carried out for six boreholes along a profile crossing the Northern Apennine chain. The heat flow varies from 95 mWm −2 in Tuscany to 23 mWm −2 in Romagna. In the light of global tectonics these values support the hypothesis that the Northern Apennine chain is a continental arc with high heat flow in the retroarc basin (Tuscany) and low heat flow in the trough (Romagna).