Created by the solidification crystallization of magma or
Created by the solidification (crystallization) of magma or lava
1. EXTRUSIVE (volcanic) Formed on surface of earth from crystallization of lava
2. INTRUSIVE (Plutonic) Formed underground from crystallization of magma
Extrusive Rocks Intrusive Rocks Cooled Quickly Cooled Slowly Small/No Crystals Medium/Large Crystals
The chemical composition of a magma/lava determines which minerals will form 8 most common elements in crust % of Crust by weight Oxygen Silicon Aluminum Iron Calcium Sodium Potassium Magnesium All Others 46. 6 27. 7 8. 1 5. 0 3. 6 2. 8 2. 6 2. 1 1. 5
Types of Magma/Lava Type Chemical Composition Rocks from this type E=Extrusive; I=Intrusive Mafic Fe, Mg, Ca E = Basalt I = Gabbro Felsic Si, O, Al, Na E = Rhyolite I = Granite Intermediate In between mafic and felsic -- some of everything E = Andesite I = Diorite
*4
FELSIC ROCK Light Colors High in Al & Si. O 2 LESS DENSE MAFIC ROCK Dark Colors High in Fe & Mg MORE DENSE
Since every mineral has a unique freezing temperature, minerals crystallize out of a magma in a very specific order.
Temperature Discontinuous Series 1200 C 1050 C Olivine Ca-rich Amphibole Biotite Na-rich 800 C Orthoclase Feldspar + Muscovite Mica + 600 C Rock Type (E/I) Ultramafic Peridotite Pyroxene Pla g Fel ioclas dsp e ar 1400 C Continuous Series Quartz Mafic Basalt/Gabbro Intermediate Andesite/ Diorite Felsic Rhyolite/ Granite
Ocean crust, mantle rock, MAFIC more dense and will sink Continental Crust, less FELSIC dense so will float INTERWhere mafic MEDIATE and felsic rock mixes • Divergent Plate Boundaries • Hot Spots • Collision Zones • Sliding Plate Boundaries • Subduction Zones
- Slides: 14