ESC 1000 Lecture Notes - Lecture 32: Extrusive Rock, Seafloor Spreading, Partial Melting
Document Summary
Heat-transfer melting caused by rising magma carrying heat. Variable amounts of dissolved gas occur in a melt. Chemical composition of molten rocks is described in terms of the proportion of sio2 it contains. Four major melt types based on % silica (sio2): felsic. Four major melt types based on % silica (sio2): intermediate. Four major melt types based on % silica (sio2): mafic. Four major melt types based on % silica (sio2): ultramafic. Crustal source= felsic magmas with some magic, intermediate magmas. Partial melting of wall rock produces new magma that mixes with magma from below. Blocks of rock fall into magma and dissolve; this process is assimilation. Different magmas may blend in a magma chamber. The result combines the characteristics of the two. As a melt cools, minerals solidify in a specific order (series) Earlycrystals settled out, removing fe, mg, and calcium. Remaining melt progressively enriched in si, al, and na.
