Slab control over HFSE depletions in central Nicaragua

Mafic lavas from the central Nicaraguan portion of the Central American vol canic front exhibit considerable variability in the magnitude of high-field -strength element (HFSE) depletions. This variability cannot be attributed to variable magmatic differentiation, or more significantly, to variable de pletion originating in the mantle wedge. Instead the HFSE depletions are th ought to be the product of variable contributions from the subducting Cocos plate, Both subducted hemipelagic sediment and subducted oceanic crust are identifiable contributors to the overall signal. The latter could exert im portant control over HFSE depletions, but only if the dehydrating crust is rutile-saturated. Slab control over HFSE depletions is possible throughout the Central American subduction zone, even where slab contributions to magm a generation are thought to be minimal, as in central Costa Rica. In some o ther subduction zones, slab control over HFSE depletions is apparent, but i n others, such as the Marianas and the Aleutians. HFSE depletions are proba bly wedge-based. (C) 2001 Elsevier Science B.V. All rights reserved.