1 - The Nature of Magmatism

Summary

The integrated aspects of volcanic and plutonic magmatic systems are rarely exposed, yet this connection is fundamentally important to understand the evolution of magma, which is important, in and of itself, to understanding planetary evolution itself. Magmatic systems beneath major volcanic centers, including the ocean ridges, are an interconnected plexus of sills and conduits. Beneath Hawaii the underlying mush column extends through the entire lithosphere, whereas beneath ocean ridges the mush column is much less vertically extensive, yet they function in very similar ways in spawning a steady flux of basaltic magma. The Ferrar magmatic system exposed in the McMurdo Dry Valleys reveals critical connections at a high level in the crust, demonstrating the operation of a magmatic mush column.