Structural Pattern And Co2-Ch4 Degassing Of Ustica Island, Southern Tyrrhenian Basin
Journal Article: Structural Pattern And Co2-Ch4 Degassing Of Ustica Island, Southern Tyrrhenian Basin
AbstractBrittle tectonics and ground degassing, including fracture-field, soil-gas and exhalation flux analyses of CO2 and CH4, were studied at Ustica Island, a Pleistocene volcanic complex in the Southern Tyrrhenian Sea. The mesoscopic fracture pattern perfectly fits an E-W-trending left-lateral strike-slip master fault, in agreement with the main morpho-structural submarine alignment including Ustica Island and Anchise Seamount. Along the SW-NE high-angle normal Arso Fault, geological evidence of reactivation with different kinematics (left- to right-lateral displacements) was recognised. Major CO2 and CH4 degassing (with fluxes up to 93,750 and 20 t km-2 a-1, respectively, and soil-gas concentrations of 11.3% and 5.7 ppm) occur over the Arso Fault. Although this fault is mapped just in the SW sector of the island, soil-gas CO2 anomalies point out its clear continuation up to the NE margin of the island. These data, together with those of previous geophysical and geochemical results from off-shore Ustica, suggest that the Arso Fault is the local evidence of a more important active, gas-bearing structure. This tectonic feature is interpreted as a reactivation of a preexistent SW-NE trend, inherited as a second-order structure of the E-W deep shear zone. The reactivation is related to the interplay among different structures of the Southern Tyrrhenian basin.
- G. Etiope, P. Beneduce, M. Calcara, P. Favali, F. Frugoni, M. Schiattarella and G. Smriglio
- Published Journal
- Journal of Volcanology and Geothermal Research, 1999
- Not Provided
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G. Etiope,P. Beneduce,M. Calcara,P. Favali,F. Frugoni,M. Schiattarella,G. Smriglio. 1999. Structural Pattern And Co2-Ch4 Degassing Of Ustica Island, Southern Tyrrhenian Basin. Journal of Volcanology and Geothermal Research. (!) .