Geochemistry at DSDP Hole 66-487

It is widely accepted that the calc-alkaline magmatism of active continental margins is caused by the melting of ocean crust in subduction zones, which in turn is due to the interaction of lithospheric plates (Dickinson, 1970; Fitton, 1971; Green, 1972). In particular, the Neogene-Quaternary magmatism of Central America is considered to be the result of the subduction of the Cocos Plate under the continent of North America in the zone of the Middle America Trench (Pichler and Weyl, 1973; Stoiber and Carr, 1974).
Recent investigations (Magaritz et al., 1978; Stern, 1974) show that the direct melting of ocean crust basalts does not result in the formation of calc-alkaline magmas, and the models of the generation of these melts would not be complete without taking into account both the processes of magmatic differentiation and their interaction with the sialic material of ocean and continental crust.