Post on 12-Jan-2016
transcript
What do rocks tell us about the Earth?
Formed from the cooling and crystallization of magma
Magma – Molten rock beneath the Earth’s surface (800 -1200°C to melt rock)
Lava – Magma that flows out onto Earth’s surface
Very similar to elements found in Earth’s crust
O, Si, Al, Fe, Mg, Ca, K and Na
Silica - Most abundant
What is wrong with this picture?
Extrusive Igneous Rocks• Fine grained
igneous rocks that cool quickly on Earth’s surface
ObsidianExtrusive
Small CrystalsCooled Fast
GraniteIntrusive
Large CrystalsCooled Slow
• Intrusive Igneous Rocks
– Coarse grained igneous rocks that cool slowly beneath Earth’s surface
Felsic (Granitic)• Light colored, High silica content, contain
quartz and feldspars
Felsic Igneous Rock
Mafic Igneous Rock
•Mafic (Basaltic)
–Dark colored, rich in iron and magnesium
•Ultra Mafic
–Low silica content, very high levels of Fe and Mg
Porphyritic Rocks• Rocks characterized by large well-formed crystals
surrounded by fine grained crystals of the same mineral
Vesicular Rocks • Spongy looking rock whose gas bubbles have broken
Partial Melting• Process where some minerals melt at low
temperatures while other minerals remain solid (Melting Points)
• Example: Ice Cube and Wax Candle
Fractional Crystallization• Process where different minerals form at
different temperatures
Bowen’s Reaction Series• Predictable, dual branched pattern in which
minerals crystallize from cooling magma
Veins• Igneous rock intrusions that contain ores (Au and Quartz)
Pegmatites• Vein deposits of extremely large grained minerals (Li and
Be)
Kimberlites• Rare, ultramafic rock that can contain diamonds and other
minerals formed only under very high pressures
Compare and Contrast magma and lava.
What two types of igneous rocks are formed as each cools?
Describe the three major mineral groups of igneous rocks. What minerals are found in each?