Magnetic signature of the Sicily Channel volcanism |
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| Authors: | E Lodolo D Civile C Zanolla R Geletti |
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| Institution: | (1) Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Trieste, Italy |
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| Abstract: | Widespread Late Miocene to Quaternary volcanic activity is know to have occurred in the Sicily Channel continuing up to historical
time. New magnetic anomaly data acquired in the Pantelleria Graben, one of the three main tectonic depressions forming the
WNW-trending Sicily Channel rift system, integrated with available profiles, are used to identify and map volcanic bodies
in this sector of the northern African margin. Some of these manifestations, both outcropping at the sea-floor or buried beneath
a variable thickness of Plio-Quaternary sedimentary cover, have been imaged by seismic reflection profiles. Three main positive
magnetic anomalies have been found: to the S–E of the Pantelleria Island, the largest emerged caldera of the Sicily Channel,
along the eastern margin of the Nameless Bank, and at the north–western termination of the Linosa Graben. Only the anomaly
located off the south–eastern coast of the Pantelleria Island, associated with a large outcropping body gradually buried beneath
a substantially undisturbed Upper Pliocene-Quaternary sediments, aligns with the trend of the tectonic depression. 2-D geophysical
models produced along seismic transects perpendicularly crossing the Pantelleria Graben have allowed to derive its deep crustal
structure, and detect the presence of buried magmatic bodies which generate the anomalies. Marginal faults seem to have played
a major role in focussing magma emplacement in this sector of the Sicily Channel. The other anomalies represent off-axis volcanic
episodes and generally do not show evident magmatic manifestations at the sea-floor. These magnetic maxima seem to follow
a NNE-SSW-trending belt extending from Linosa Island to the Nameless Bank, where pre-existing crustal anisotropies may have
conditioned magma emplacement both at deep and shallow crustal levels. In general, data analysis has shown that there is a
structural control on magma emplacement, with the major magmatic features located in specific locations like boundary faults
and transfer zones, in a manner similar to that found along several segments of the East African Rift system. |
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