マントル上昇流中のマグマの発生と移動 : 海嶺玄武岩の化学組成への影響

概要

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The local variation of mid-ocean ridge basalt compositions show some systematic trends depending on the individual ridges, which are interpreted to result from lateral melt migration in the partially molten mantle rock. The effect of lateral melt migration on the concentrations of minor components in the melt is evaluated by a parameter which represents the gradient of lateral melt flux. Melt generation in near fractional condition is associated with positive values of the parameter, while melt supplement, represented by its negative values plays an important role as well, even though this process has rarely been taken into consideration before. Due to more or less non-uniform lateral melt flux in the melting region, melts derived from the same depth should have different compositions. The chemical characteristics of MORB compositions observed in Red Sea rift, 12°50' NEPR, FAMOUS area and Galapagos spreading center are explained by a common chemical effect of the lateral melt migrations that are caused by different driving forces in different scales.
1997-04-25