Figure 6. Layering in gabbro. This image shows alternating layers rich in dark green pyroxene and white feldspar. These layers indicate that successive pulses of magma entered the magma chamber from below with intervening quiet periods in which the newly forming crystals could separate by density, with the denser pyroxene settling first. Careful mapping of such layering may reveal much about the structure of the magma chamber.
Last updated on May 13, 2010