Relate silica content to crystallization from a magma. What ...

[RODY.ELKHALIL]

Relate silica content to crystallization from a magma.
 
  What will be an ideal response?

Question 2

Most of the batholithic-sized plutons found in the continents are composed of
 
  A) obsidian.
  B) basalt.
  C) granite.
  D) sandstone.

[amandalm]

Answer to Question 1

Answer: First of all crystallization allows a single magma to generate several different igneous rocks. Minerals with high melting points, have a low silica content, so will crystallize first, followed by minerals with lower melting points (those containing larger amounts of silica). As crystallization proceeds, the composition of the liquid in which the crystals form changes. It becomes depleted in the constituents of minerals that have already crystallized and enriched in the constituents of minerals yet to crystallize, which acts to increase the silica content of the remaining liquid.

Answer to Question 2

Answer: C

[RODY.ELKHALIL]

Thank you!

[amandalm]

Always glad to help...