Part 3 - Interpret the data

Question 5. Do MORB's display global geochemical variations beyond what should be expected from fractionation? What are the magnitude of those variations? Are they in excess of the analytical uncertainties (~0.5 wt.%)?

Question 6. Are the axial traces of the world's mid-ocean ridges all at the same depth below sea level?

Question 7. Formulate a hypothesis relating the elevation of a mid-ocean ridge segment and rates of melting in the underlying mantle source.

Question 8. If Na is largely an incompatible element during partial melting of the mantle, does your plot of Na_8.0 vs. elevation support your hypothesis in #7 above?

Question 9. If Fe is largely a compatible element during partial melting of the mantle, does your plot of Fe_8.0 vs. elevation support your hypothesis in #7 above?

Question 10. CaO/Al₂O₃ increases (in the melt) with increasing amounts of melting as long as clinopyroxene is retained in the source rock. Does this observation support your hypothesis in #7 above?