Submarine magmatism in the Sicily Channel Rift began in the early Pliocene and lasted until almost 200 yr ago. Wepresent here petrological and geochemical data on volcanic rocks dredged from Graham and Nameless banks andPantelleria seamounts in the Pelagian sector of the Sicily Channel Rift. Petrological evidence suggests that the ascentof magmas to the surface was relatively rapid, probably through channels superimposed over the major tectonicdiscontinuities of the Rift. Major and trace element data indicate an ocean island basalt affinity for Graham andNameless bank alkaline lavas and a depleted tholeiitic signature for one Pantelleria seamount, which had a shallowermantle source. Sr-Nd-Pb isotopic compositions suggest a heterogeneous mantle source involving both focus zone(FOZO) and high-m (HIMU) components. Lead isotopic compositions are slightly less radiogenic in the tholeiitic basaltand more radiogenic (closer to HIMU) in the alkaline lavas.We hypothesize that a decompressional meltingmechanismaffected the mantle beneath the Sicily Channel at different levels. Our data fit in a regional scenario characterizedby the presence of HIMU or FOZO components in alkaline and calc-alkaline volcanics all around Sicily. The explanationfor the common isotopic composition could lie in a (fossil) plume head that variably contributed to magmatogenesisin response to variable lithospheric stretching.
|Numero di pagine||11|
|Rivista||THE JOURNAL OF GEOLOGY|
|Stato di pubblicazione||Published - 2006|
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