Modification of an oceanic plateau, Aruba, Dutch Caribbean: Implications for the generation of continental crust

摘要: The generation of the continental crust may be connected to mantle plume activity. However, nature this link, and processes involved, are not well constrained. An obstacle understanding relationships between plume-related mafic material associated silicic rocks is that later tectonic movements liable obscure original relationships, particularly in ancient greenstone belts. Studies younger analogous regions help clarify these relationships. On island Aruba southern Caribbean, a sequence partly deformed volcanic intruded by predominantly tonalitic batholith exposed. lavas show geochemical isotopic affinities with other basaltic, picritic komatiitic crop out elsewhere Caribbean - documented as belonging an 88-91 Ma oceanic plateau, which allochthonous respect Americas, thought have been formed Pacific region. ~85 ~82 share some characteristics (high Sr Ba, low Nb Y) Archaean tonalite-trondhjemite-granodiorite (TTG) suites. Field suggest deformation plateau sequence, possibly related collision subduction zone, was synchronous intrusion batholith. New incremental heating 40Ar/39Ar dates, combined existing palaeontological evidence, cooling occurred shortly after eruption basalt sequence. Sr-Nd data for both rock suites uniform (87Sr/86Sri≈0.7035, eNdi≈+7), whereas Pb isotopes more variable (Plateau sequence: 206Pb/204Pb=18.6-19.1, 207Pb/204Pb=15.54-15.60, 208Pb/204Pb=38.3-38.75; batholith: 206Pb/204Pb=18.4-18.9, 207Pb/204Pb=15.51-15.56, 208Pb/204Pb=38.0-38.5). This suggests there has minor sedimentary input into source region limited time interval basaltic magmatism makes normal subduction-related origin tonalites improbable. Instead, models involving derivation tonalite from partial melting or alternatively, genesis unusual zone environment, investigated.