Teaching with the EarthChem Geochemical Database
Integrating Research and Education > EarthChem > Mid-Ocean Ridge Basalts > Part 3 - Interpret the data

Part 3 - Interpret the data


Question 7. 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 8. Are the axial traces of the world's mid-ocean ridges all at the same depth below sealevel?

Question 9. What does your answer to #8 imply about rates of eruption along the mid-ocean ridge system?

Question 10. What does your answer to #9 suggest about rates of melting, or amounts of melt in the mantle source regions below the ridges?

Question 11. Formulate a hypothesis relating the elevation of a mid-ocean ridge segment and the amount of melting in the underlying mantle source.

Question 12. If Na is largely an incompatible element during partial melting of the mantle, does your plot of Na8.0 vs. elevation support your hypothesis in #11 above?

Question 13. If Fe is largely a compatible element during partial melting of the mantle, does your plot of Fe8.0 vs. elevation support your hypothesis in #11 above?

Question 14. 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 #11 above?


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