Layered Mafic Intrusions

Question 1

Name the different types of layerings in mafic intrusions

Answer 1

Modal layering: Variation in modal proportions

Phase layering: Var. in primary (Cumulus) minerals (Appearance/ disappearance)

Cryptic layering: Var. in mineral composition (Cannot be seen by the eye, but measured)

Question 2

What does SH mean?

Answer 2

SH:Sandwich Horizon, de sidste dråber af magma er i denne horisont. efter at ting er blevet
krystaliseret fra toppen og bunden.

Question 3

What is the size of a layered mafic intrusion?

Answer 3

Kan være 6-8 km tykke og være udbredt over flere km^2.
Alderen på lagdelte intrusioner: Fra Arkæiske til Eocene, så markant forskellige.

Bushveld og Skaergård er de vigtigste at kende til

Question 4

Why are layered mafic intrusions important?

Answer 4

Include many economic minerals

Question 5

Uniform modal layering

Answer 5

Where two distinct layers are seen and created. Fx. in Bushveld South Africa, where the layering is between
Black layers: Oxide with chrome White layers: Mottled Anorthosite