Late Jurassic oceanic crust and Upper Cretaceous Caribbean plateau picritic basalts exposed in the Duarte igneous complex, Hispaniola

Four distinct rock units have been recognized near El Aguacate, in the Jani co-Juncalito-La Vega area of the Duarte complex (Dominican Republic): (1) s erpentinites crosscut by numerous diabasic dikes, (2) basalts interbedded w ith Late Jurassic ribbon cherts, (3) picrites and ankaramites relatively en riched in incompatible trace elements, and (4) amphibolites and gneissic am phibolites chemically similar to Oceanic Plateau Basalts. Similar Ar-Ar age s of late magmatic amphibole from a picrite, and hornblende from an amphibo lite (86.1 +/- 1.3 Ma and 86.7 +/- 1.6 Ma, respectively), suggest that the Duarte picrites are contemporaneous with the Deep Sea Drilling Program Leg 15 and Ocean Drilling Program Leg 126 basalts drilled from the Caribbean oc eanic plateau. These basalts are associated with sediments containing Late Cretaceous faunas. Sr, Nd, and Pb data show that enriched picrites and amph ibolites are isotopically similar to mafic lavas from previously described Caribbean plateau and Galapagos hotspot basalts. Major element, trace eleme nt, and lead isotopic features of Late Jurassic basalts and diabases are co nsistent with those of normal oceanic crust basalt. However, these basalts differ from typical N-MORB because they have lower epsilon Nd ratios that p lot within the range of Ocean Island Basalts. These rocks appear to represe nt remnants of the Caribbean Jurassic oceanic crust formed from an oceanic ridge possibly close to a hotspot. Later, they were tectonically juxtaposed with Late Cretaceous slices of the Caribbean-Colombian plateau.