Mantle Melting and Basalt Extraction by Equilibrium Porous Flow

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Science  22 Dec 1995:
Vol. 270, Issue 5244, pp. 1958-1961
DOI: 10.1126/science.270.5244.1958


The chemical composition of mid-ocean ridge basalt, the most prevalent magma type on the planet, reflects the melt's continuous reequilibration with the surrounding mantle during porous flow. Models of basalt extraction that account for the observed uranium-series disequilibria on the Juan de Fuca ridge constrain both the abundance of melt beneath ridges (0.1 to 0.2 percent) and the style of mantle melting. Unlike models that incorporate near-fractional melts (dynamic melting), mixing of equilibrium porous flow melts derived from heterogeneous source materials quantitatively explains the uranium-series observations.