Beryllium systematics in young volcanic rocks: Implications for 10 Be

摘要: Beryllium is an incompatible trace element that closely parallels neodymium in its geochemical behavior. Be analyses conducted on well-characterized oceanic and arc volcanic rock suites, as well marine sediments, suggest a bulk solid/liquid distribution coefficient of 0.03–0.06 for melting the mantle crystallization basalts. The Be/Nd ratio many rocks from diverse tectonic environments approximately .05, similar to chondrites. Be data samples arcs show there are significant variations 10Be/9Be among different arcs, 10Be not due concentration alone. For at least one volcano (Bogoslof), constant vary by factor three both their concentrations, suggesting inherited magmatic signature simply result contamination near surface. In addition, Be, Nd Pb isotope systems this all consistent with model which small amounts sediment were incorporated into Bogoslof source region—provided wedge has isotopic characteristics depleted MORB. Since exists only uppermost tens meters efficient return flux subduction zones.