Geob 103, Lecture 2 01/14/2014
The formation of Magma & igneous rocks
Rock ▯ Liquid > Rock
Igneous processes involve melting rocks to form magma and solidification of this magma to form a new
Igneous products form more magma, crystallizes below surfaces or erupts as lava and other materials.
Igneous rocks can be formed
Surfaces: called extrusion (synonym to volcanic rock)
Pyroclastic deposits (Philippines)
Composition of rocks
Cooling of molten material
Each mineral in magma crystalizes at a particular temperature > crystallization temp.
Magma: High content of Silica: a compost of silicon and oxygen.
Magma also has gas which is why some rocks are full of holes.
Lava has no gas
Based on the content of silica we have 2 types of rocks Ultramafic: More iron less silicon
Mafic: stands for magnesium and iron.
Between these two types are intermediate rocks
Felsic: Feldspar and silicon.
Not a fixed amount of silicon. A gradual transition betwee