Island Arc Magmatism Flashcards
1
Q
What type of volcanic rocks can be found at island arcs? Why?
A
Basaltic Andesite - Andesite
Increase in silica content, decrease in Fe and low amounts of heat flow
2
Q
What is calc-alkaline magma in terms of island arc magnetism?
A
Early crystallization of Fe/Ti oxides
3
Q
Why is there early crystallization of Fe-Ti oxides in calc-alkaline magmas?
A
Related to amount of water content
4
Q
Why do REE graph slopes vary in height with FX?
A
Removal of olivine, plagioclase and pyroxene
5
Q
What are the 2 processes that occur in a subdued slab environment?
A
Dehydration - release water in mature arcs with no slab melting
Slab melting - dehydration of chlorite and amphiboles that release water above wet solidus
6
Q
What are the 5 source components of island arc magmas
A
- Crust part of subduction slab
- Mantle wedge
- Arc crust
- Lithospheric mantle of subduction plate
- Asthenosphere beneath slab
