Is the Vourinos Complex an island arc ophiolite?

A geochemical study has been undertaken on the Vourinos ophiolites, northern Greece, a complex long known for its unusual characteristics such as an environment of acidic rocks and a calc-alkaline chemical affinity. The Nd-Sr isotopic ratios and the Hf/Th and Ta/Th ratios are indicative of an island arc origin for Vourinos as opposed to the mid-oceanic ridge origin inferred for other ophiolites such as Inzecca, Corsica. Other data on trace elements confirm that the cumulative suite and the lavas originated from the same magma through a simple fractional crystallization process and show that this magma would have formed through partial melting of an already highly-depleted material. It is thus possible to distinguish ophiolites with MORB characteristics from island arc ophiolites such as the Vourinos Complex, the existence of the latter type imposing new constraints on the possible tectonic processes for emplacement.