ZONING

Question 1

compositionally zoned crystals

Answer 1

concentric compositional variations within indiviual crystals.

indicate disequilibrium crystallisation with a solid solution minerals series (e.g plagioclase)

Question 2

normal zoning

Answer 2

high-temp, Ca-richs cores to low-temp, Na-rich rims

Question 3

reverse zoning

Answer 3

opposite to normal

Question 4

oscillatory zoning

Answer 4

composition of plagioclase fluctuates back n forth