Metabasites from the northern serpentinite belt (Cuba) and a metamorphic perspective of the plate tectonic models for the Caribbean region
Abstract
The analysis of metamorphosed magmatic rocks along the northern serpentinite belt (Cuba) suggest a variety of tectonic settings of formation and metamorphism. Slightly deformed coherent bodies of metabasites from Cajálbana (western Cuba) and Iguará-Perea (central Cuba) underwent ocean-floor type metamorphism at low-pressure (<3kbar) amphibolite locality amphibolite (locally granulite) facies conditions. 40Ar/39Ar plateau ages on amphiboles have yielded 88.0 +/- 3.2 (Iguará-Perea) and 129.8 +/- 1.9 Ma (Cajálbana). These rocks have tholeiitic (Cajálbana) and calc-alkaline (Iguará-Perea) signatures and evidence of formation in suprasubduction environments (Th, Nb and Sr anomalies). Based on geochemical similarities with the arcrelated metamorphic Mabujina complex (central Cuba), it is hypothesized that the Iguará-Perea complex may represent the roots of an embryonary or abandoned arc. Indeed, arc-related (instead of mid-ocean ridge) thermal focuses for metamorphism are favored because of the consistent relationships between the age of metamorphism and geochemistry of the protholiths and the age and geochemistry of the Lower and Upper Cretaceous volcanic arc suites of Cuba. The Güira de Jauco amphibolites (eastern Cuba) have NMORB and E-MORB basaltic to picritic composition that suggest an Upper Cretaceous plateau basalt origin of the protolith. These rocks were strongly deformed and metamorphosed to intermediate pressure (6-8 kbar) amphibolite facies conditions, indicating collision-related metamorphism. The documented Cretaceous formation of suprasubduction and intraplate oceanic complexes must be added to the inferred event of formation of oceanic lithosphere at Upper Jurassic to Lower Cretaceous times in ocean-ridge environments, and put important constraints to models of plate tectonic evolution of the Caribbean region.
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To Cite this article: García-Casco, A., Perez e Arce, C., Millán, G., Iturralde-Vinent, M.A., Fonseca, E., Torres-Roldán, R.L., Nuñez-Cambra, K., Morata, D. (2003): Metabasites from the Northern Serpentinite Belt (Cuba) and a metamorphic perspective of the plate tectonic models for the Caribbean region. TALLER DEL PROYECTO Nº 433 DEL PICG / UNESCO "TECTÓNICA DE PLACAS EN EL CARIBE" MEMORIAS GEOMIN 2003, LA HABANA, 24-28 DE MARZO. ISBN 959-7117-11-8. TPICG- 29. CD-rom: Centro Nacional de Información Geológica (La Habana), 9 páginas, 2003.
