predominant, and in many volcanic areas, as on the island of Linosa and in the submarine volcanoes of Adventure plateau and Graham and Nameless Banks, are the only products found. The general petrologic features of the volcanism of the Sicily Channel point to an anorogenic magmatism similar to that found in continental rift areas (Corti et al. 2006). The trace element distribution is comparable with that observed in intraplate basalts or ocean island basalts. Petrological evidence suggests that the ascent of magmas to the surface was relatively rapid, probably through channels superim- posed over the major tectonic discontinuities of the rift. Major and trace element data indicate an ocean island basalt affinity for Graham and Nameless Banks alkaline lavas and a depleted tholeiitic signature for one Pantelleria seamount, which had a shallower mantle source (Rotolo et al. 2006).
On a regional scale, the distribution of the positive magnetic anomalies appear to follow two main trends: one (where the largest magnetic anomaly was found) follows the axis of the Pantelleria Graben, slightly shifted to the south; the other situated along a broad NNE-SSW-oriented belt extending from Linosa Island to the eastern margin of the Nameless Bank. This belt partly coincides with that proposed by Argnani (1990) on the basis of bathymetric, volcanic, and seismic considerations, and was interpreted as a strike-slip transfer fault zone separating the rift system in two independent areas, the Pantelleria Graben to the west and the Malta and Linosa grabens to the east. The factors playing a major role in the distribution and affinity of the Sicily Channel volcanic rocks appear to be: (a) the petrological characteristics of the mantle source; (b) the geodynamic processes responsible of the crustal rifting, which in turn depends of the grade of intensity of the extensional stresses; (c) the presence of pre-existing crustal tectonic structures which favoured the rising of the mag- matic manifestations.
The main magnetic anomaly is closely related to a large magmatic body in correspondence to a boundary fault of the south–western Pantelleria Graben. Boundary faults seem to have played a crucial role in the distribution of volcanic manifestations, probably because they channeled the magmatic material along the principal fault planes. The other two anomalies seem to be either related to: (a) a sort of off-axis volcanism, because they are located relatively close to the boundary faults, but in an external position on the shoulders of the rift, as occurring in other divergent systems, like a segment of the East African Rift, where Bosworth (1987) described paired zones of volcanism and lithospheric thinning off-axis from the rift proper; or (b) to a focussing of magma emplacement in correspondence with a structurally complex area (where pre-existing structures are present) representing a transfer zone between the Pantelleria and Linosa/Malta grabens. Geophysical data show that the rifting in this sector of the African platform is a passive response to a regional stress field, allowing hot mantle rocks to penetrate locally the lithosphere. Ascend- ing magmas within the Pantelleria Graben floor seem to migrate from the S to E sector of the depression toward the N–W sector, which is almost entirely floored by igneous material, and where the volcanic edifice of the Pantelleria Island, elongated in the same direction as the rift itself, is emerged (Civile et al. 2010).
There are some analogies between the Sicily Channel volcanism and the main Ethiopian rift volcanism, where the structural control (both inherited and/or rift-related) on magma emplacement played a major role, with major magmatic features located in specific structural locations like boundary faults and transfer zones (Corti 2008). The sequence of events in this segment of the East African Rift system includes a first episode of volcanism (possibly with coeval doming), later followed by lithospheric rifting connected to the Afar plume, that in turn may be a superficial expression of a deeper (lower mantle) superp- lume (Corti 2009).
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