First description of a metamorphic sole related to ophiolite obduction in the northern Caribbean: Geochemistry and petrology of the Güira de Jauco Amphibolite complex (eastern Cuba) and tectonic implications

• The Güira de Jauco Amphibolite Complex is interpreted as a sub-ophiolitic metamorphic sole.
• It constitutes the first description of a metamorphic sole in the Caribbean realm.
• Amphibolite basaltic/gabbroic protoliths formed part of the upper oceanic crust of a back-arc basin.
• P–T estimates indicate peak conditions ~ 655 °C and 8.6 kbar.

The Güira de Jauco Amphibolite Complex underlies the Mayarí–Baracoa Ophiolitic Belt (eastern Cuba) and is composed of highly foliated amphibolite, locally with blocks of sheared serpentinitie that enclose concordant layers of amphibolite. These amphibolites are interpreted as remnants of a sub-ophiolitic metamorphic sole likely formed during late Cretaceous times before the initiation of the collision between the Caribbean and the North American plates. The complex includes common amphibolites (Hbl + Pl ± Ep ± Ttn ± Rt ± Qtz ± Ap), garnet amphibolites (Hbl + Grt + Pl + Ep ± Ttn ± Qtz ± Ap) and clinopyroxene amphibolites (Hbl + Pl + Cpx ± Ep ± Ttn ± Qtz ± Ap). Geochemical data indicates that the protoliths are igneous mafic rocks of basaltic composition that likely formed part of the upper and lower(?)crust of an oceanic lithosphere. Rare Earth element contents suggest a Mid-Ocean Ridge Basalt (MORB) origin. However, the enrichment in Large-Ion Lithophile elements and the depletion in NbTaTi as compared to Normal-MORB, suggests a suprasubduction scenario, either a back-arc or a fore-arc setting. The pressure–temperature estimates of metamorphism indicate that the entire amphibolite body underwent similar peak metamorphic conditions at 650–665 °C and 8.5–8.7 kbar (ca. 30 km depth), corresponding to a relatively high apparent geothermal gradient of 23 °C/km.This data, together with field observations and available age data (KAr ages and the apparent stratigraphy of the metamorphosed (high P) volcanic-arc terrane of eastern Cuba) suggest that the development of the ophiolite and the initial stages of obduction occurred shortly after subduction initiation in a back-arc environment in Late Cretaceous times. Subsequent subduction/collision/accretion of platform- and arc-derived high-pressure metamorphic units took place at the leading edge of the Caribbean plate in response to arc–continent collision (from 70 Ma to Eocene).