We present a new model for anhydrous melting in the spinel and plagioclase stability fields that provides enhanced predictive capabilities for the major element compositional variability found in mid-ocean ridge basalts (MORBs)….We show that to explain the global data set of crustal thickness, Na8, Fe8, Si8, Ca8/Al8, and K8/Ti8 (oxides normalized to 8 wt % MgO) require a relatively narrow zone over which melts are pooled to the ridge axis. In all cases, our preferred model involves melt transport to the ridge axis over relatively short horizontal length scales (~25km). This implies that although melting occurs over a wide region beneath the ridge axis, up to 20–40% of the total melt volume is not extracted and will eventually refreeze and refertilize the lithosphere.
Link to MATLAB® routines for BG15 MORBmelting model and example scripts for Figure 4 & Figure 7.