A Late Cretaceous Adakitic intrusion from Northern Haiti: additional evidence for slab melting and implications for migration of ridge-trench-trench triple junction during the Cretaceous in the Greater Antilles

Description

We present a new U-Pb zircon age and geochemical data from an intermediate calc-alkaline pluton with adakitic affinity from NW Hispaniola (Haiti). The data provide important constraints and offer new insight on the Late Cretaceous (~90 Ma) development and geological evolution of the Greater Antilles Arc (GAA). The pluton intrudes Cretaceous basalts and mafic basic tuffs of the volcanic arc domain in the Massif du Nord (northern Haiti), equivalent to the Tireo Fm (Cordillera Central) in the Dominican Republic. The calc-alkaline, low-K tonalite shows LREE enrichment, and HREE depletion and have geochemical features similar to adakites, including 67.11 wt.% SiO2, high Na2O contents (3.69 wt.%), and high Sr/Y (38.6). U-Pb SHRIMP zircon dating yielded a concordant 206Pb/238U emplacement age of 88.9 ± 1.1 Ma, similar to other calc-alkaline intrusions in Hispaniola and Cuba related to the Cretaceous GAA. We link the presence of rocks with adakitic affinities in Eastern Cuba (La Corea and Sierra del Convento Mélanges), Haiti (Massif du Nord; present study), and Dominican Republic (Cordillera Central) with subduction of the Proto-Caribbean ridge and eastward (present coordinates) migration of the corresponding ridge-trench-trench triple junction since at least ~120 Ma in eastern Cuba to the mid-Cretaceous (~90 Ma) in Hispaniola. Here we show that this migration is not consistent with left-lateral oblique subduction and propose that it was not characterized by steady motion but by sudden jumps resulting from the segmentation of the proto-Caribbean ridge by transform faults. Ridge subduction and jumping triple point migration should have been active during the Late Cretaceous to early Tertiary, when the activity of the Proto-Caribbean ridge vanished.

Abstract

International audience

Additional details