1. How do mantle rocks melt ?
Adding water to the system: flux melting
Decompress the rocks- decompression melting
Heating
Path 2
Path 3
Path 1

2. Magmatic activity and plate tectonic setting

4. Liquid line of descent

5. How do igneous rocks evolve?
Fractional crystallization

6. How do igneous rocks evolve?
Fractional crystallization

7. How do igneous rocks evolve?
Fractional crystallization

8. Phaneritic Aphanitic Porhpyritic Glassy Vesicular Pyroclastic
Igneous Textures
Phaneritic
Aphanitic
Porhpyritic
Glassy
Vesicular
Pyroclastic

9. Phaneritic
Phaneritic – individual grains in an igneous rock are large enough to be identified without the aid of a microscope

10. Aphanitic – individual minerals are present in the igneous rock
but in particles so small that they cannot be identified without a microscope

11. Porhpyritic
Porphyritic-igneous texture referring to relatively large isolated crystals in a mass of fine texture (aphanitic) groundmass

12. Glassy textured igneous rocks are non-crystalline.
Generally indicate very rapid cooling.

13. Vesicular –Texture characterized by
Vesicles (holes, pores, or cavities) within
the igneous rock. Vesicles are
the result of gas expansion
(bubbles). Bubbles can by filled by
secondary minerals due to fluid infiltration
(Amygdule).

14. Pyroclastic – composed chiefly of (variable) rock fragments.

15. Gabbro

16. Granite

17. Andesite

18. Classifying igneous rocks

19. Streckeisen diagram (1974)

20. How to classify a igneous rock
Estimate plutonic or volcanic based on texture
modal abundance of mafic vs felsic minerals (dark vs light colored)
If M (%mafic minerals) is <90% use Streckeisen diagram
Determine modal abundances K-feldspar, Plagioclase , Quartz,
renormalize to 100%, plot in QAPF diagram.