Geochemical Fingerprinting of Ancient Oceanic Basalts: Classification of the Cuban Ophiolites

Mesozoic ophiolites are an important feature of Cuban geology. Although Cuban ophiolites have been studied over the past 40 years, there is still need for systematic studies regarding their internal structure, geochemical characteristics, and emplacement mechanisms. The ophiolites are distributed along the so-called “Northern” and “Eastern” Cuban ophiolite belts, and are strongly dismembered and intermingled mainly with Cretaceous volcanic arc rocks. Ophiolite-associated basalts along the northern Cuban orogenic belt record magmatic history of the ophiolite formation from the Protocaribbean seafloor spreading to subduction initiation stage. We have compiled geochemical data of 15 oceanic basalt samples from previous works, together with data of an analyzed sample during this study. We discuss geochemical criteria based on immobile element proxies for fractionation indices, alkalinity, mantle flow and subduction addition, and field relationships, providing a comprehensive ophiolite classification according to the tectonic setting at which these ophiolites formed. The lavas exhibit three magmatic types. One type has subduction-related fingerprint with dominance of boninite and IAT affinities, likely related to a forearc setting. The second type has a MOR-type (N-MORB and E-MORB) signature, most of them carrying a subtle influence of subduction component, overlapping a border of the backarc field. Subordinately, a transitional type occurs with MOR-type-OIB fingerprint that is considered most likely plume-type ophiolite. The results show then that the studied lavas correspond mostly to subduction-related ophiolite and some of them have incorporated subduction component probably during the time when the Protocaribbean oceanic lithosphere downgoing beneath the Caribbean plate. Some rare remnants of plume-MORB-type ophiolite have also occurred.