Answers to questions on igneous rocks, physical geology lecture.
what different ways can the crystallization process be studied
- experimentally (melt, cool and quench in
lab to arrest process at different stages).
- theoretically (physical chemistry).
- use of rock textures/associations.
controls the grain size of an igneous rock?
- rate of cooling: faster = finer, slower =
- temperature contrast between igneous melt
and surrounding rock or air or water determines how fast heat flows out of the melt, and hence the speed of cooling.
Convection in water and air contributes to faster cooling.
- fluid content: wet = coarser, dry = finer.