Flashcards
Igneous Rocks
Cards in this deck (13)
- 12 types of igneous rockExtrusive and Intrusive
- 2What is the texture of igneous rocks normally like?Latter has a coarser texture.
Intrusive - more time for individual atoms to find their place in the crystal lattice, so the crystals are larger. - 3How was the distinction between intrusive and extrusive rocks determined by?Observations of lavas and granites. Observed coarse grain granite and alteration of sedimentary rock in contact- must have been underground intrusion.
- 4What two categories are extrusive rocks in?Lavas and pyroclastic flows.
- 5How are igneous rocks charactrised by mineralogy?How much SIO4 is present, igneous rocks with lots of silicate are termed felsic.
- 6How are igneous rocks formed at mid ocean ridges?-Convection cells cause rising magma material
-moves to surface, pressure is reduced
-top of mountains, boiling point of water lowered same way melting point of rock is lowered
-melts to form magma via decompressional melting
-the mafic mantle material melts to form magma
-formed rocks are mafic: basaltic - 7How are igneous rocks formed at subduction zones?-water driven off subducted slab changes composition of overlying mantle
-reduces melting point - causes melting
-overlying melted rock is mix of mafic mantle and felsic crust so felsic magma made
-these then intruded/extruded and form rhyolites and andesites - 8How are igneous rocks formed at mantle plumes-Causes melting of mantle thru plume to erupt mafic rocks in hotspot locations
- 9What is metamorphismA way of bringing a rock formed in one environment into equilibrium with a new one
- 10What is sea floor metamorphism?Seawater percolates through fractured basalts and reacts to form altered basalts
- 11What is contact metamorphismLocalised heating of surrounding rocks by igneous intrusions
- 12What is regional metamorphism?Over large areas where plates collide due to rocks being exposed to high temperatures
- 13—
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- Flashcards on Igneous Rocks, created by Laura G on 07/02/2018.
- Created by
- Laura G · Feb 2018
- Updated
- Feb 7, 2018
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