GEOSC 020 Study Guide - Midterm Guide: Mid-Ocean Ridge, Magma Chamber, Subduction
Document Summary
5. 6 what processes influence the composition of a magma: crystallization: Mafic crystals sink to bottom: mixing: when two different magmas come in contact with one another. Creates intermediate rock: assimilation: when a magma chamber is hotter than the melting temp of the felsic rock separating two chambers and melts through the wall and melts the rock into the next magma chamber. Host rock is dislodged, melts and is incorporated into magma body. 5. 5 what causes a rock to melt: decompression: pressure is released; causing the (at least slightly hot) rock/magma to uplift so quickly that it does cool. Ex: ocean ridge/ divergent boundary: by water: adding water lowers melting temperature of rocks. Will see partial melting in subduction zone with water (ocean-ocean convergent boundary: heating: raise the temperature and some rocks will melt. Raise the temperature and raising the pressure will cause the rock to stay solid because: pressure acts to keep rocks solid.
