Magma chambers on a slow burner

摘要

The worlds ocean basins are constantly being regenerated by an 80,000-kilometre-long volcanic system of mid-ocean ridges, where Earth's mantle melts to form magma that eventually produces the basaltic floor of the oceans. The composition of ocean-floor basalts is one of the main sources of information about Earth's deeper interior. On page 698 of this issue, O'Neill and Jenner re-examine the chemical compositions of basaltic lavas from this global mag-matic system. They find new, and remarkably systematic, chemical relationships between the concentrations of 'incompatible' trace elements (so named because they are largely excluded from magmatic crystals) and that of magnesium oxide (MgO).