Geochemical evidence for island-arc origin of the Villa de Cura blueschist belt, Venezuela

Abstract

New geochemical data from the Villa de Cura blueschist belt indicate that it is a subducted (and exhumed) oceanic island-arc terrane. The majority of the metabasalts were oceanic island-arc tholeiites (7-23 wt% MgO), though more evolved tholeiites are also found. Rare earth element (REE) and immobile trace element data from the Villa de Cura belt exhibit island-arc signatures, including (1) fl at to light enriched REE patterns, and (2) enrichment of large ion lithophile elements relative to high fi eld strength elements with a strongly negative Nb anomaly. Thus, the Villa de Cura belt is similar to other Albian-Aptian age oceanic island-arc tholeiites documented throughout the Caribbean in Cuba, Hispaniola, Puerto Rico, Tobago, and Bonaire. It is not related to the Cretaceous Caribbean-Colombian oceanic plateau. From our new geochemical data and previously published metamorphic data, we propose that the Villa de Cura blueschist sequence represents two forearc slivers of the "Great Arc of the Caribbean" that were subsequently subducted and amalgamated during exhumation.

Metamorphic history of riebeckite- and aegirine-augite-bearing high-pressure–low-temperature blocks within the Siuna Serpentinite Mélange, northeastern Nicaragua

“…These HP-LT rocks occur as (1) coherent oceanic and continental metamorphic belts (e.g. Villa de Cura belt and Chuacús complex; Unger et al 2005;Martens et al 2012), (2) blocks, lenses, or knockers within subduction-related mélanges (e.g. North and South Motagua mélanges and Cordillera de la Costa belt; Harlow et al 2004;Sisson et al 2005), and/or (3) exotic blocks within younger conglomerates and olistostromic units (e.g.…”