1. (the best!)
Igneous Rocks

2. Igneous textures: Magma Lava Pyroclastics
Molten rock solidifies below surface
Coarse grained
Lava
Molten rock solidifies at/near surface
Fine grained
Pyroclastics
Chunks/pieces of molten rock blown into air
Clasts welded together

3. Chemistry Composition: what minerals make up the rock Affected by:
Tectonics
Melt source
Country rock
Temperature
Water content

4. Bowen’s Reaction Series

5. Composition (Mode) 3 general categories of igneous rock: Mafic
Rich in Ca, Mg, Fe
Si poor (45-52%)
High T, low H2O content
Less viscous
Intermediate
Felsic
Si (>69%), K, Al rich
Lower T, high H2O
More viscous

6. Texture Phaneritic Aphanitic Porphyritic
Crystals are large enough to see
Aphanitic
Microscopic crystals
Porphyritic
Two different crystal sizes (due to change in temp as cooling)
Phenocrysts
Matrix

7. Porphyritic texture
Large white crystals are phenocryts
Aphanitic basalt (mafic composition) constitutes the groundmass

9. Granite and Rhyolite: Felsic
What are the textures in these two rocks ?
Phaneritic
Aphanitic

10. Andesite & Diorite: Intermediate
Aphanitic
Phaneritic
What are the textures in these two rocks ?

11. Basalt & Gabbro: Mafic
Aphanitic
Phaneritic

12. Peridotite- the abundance (more than 40%) of Olivine crystals makes the rock take on a green appearance

13. Volcanic Glass Obsidian- conchoidal fracture
And association with volcanic rocks
Volcanic
Glass

14. Tuffs & Breccias- look like sedimentary rock Tuffs & Breccias
But they are not….it is volcanic ash that is lithified

15. Pyroclastics
Lava flow
Volcanic neck
Igneous dike
Igneous Sill
Batholith

16. Sierra Nevada Batholith- Home to Yosemite National Park and a lot of Granites and Grano-diorites

17. Sierra Nevada Batholith

18. Intrusions Igneous rock pushes between or through pre-existing rock
Dike
Rock cuts through
Sill
Rock is parallel to pre-existing
Neck
Cooled core of extrusion
Laccolith
Makes bulge shape between rock layers

19. An igneous dike-
Discordant with surrounding rock
It cuts across other rocks
An igneous sill-
Concordant with surrounding rock
It runs parallel to other rocks

20. Volcanic Necks & Igneous Dikes
igneous sill
Igneous sill