igneous rocks properties and identification. igneous rocks mt. baker is a volcano made of igneous...
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Igneous RocksIgneous Rocks
Properties Properties andand
IdentificationIdentification
Igneous rocks
Mt. Baker is a volcano made of igneous rocks
Igneous - formed by crystallization from
molten magma.
Sedimentary – I like this picture
Rocks of the Vancouver Region
C & T p. 20
Intrusive (Plutonic) Rocks –
•Formed by slow crystallization deepbeneath the Earth’s surface.•Large visible crystals – phaneritic•Identified by mineral content.
Igneous Rocks
Extrusive (Volcanic) Rocks -
Formed by rapid crystallization on
the Earth’s surface
Crystals only visible under a
microscope - aphanitic
Identified by mineral content and
structure
Golden Ears, Maple Ridge.
Mt. Garibaldi, Squamish.
Colour Index 10% 20% 25% 50% 95%
Quartz
Fine grained (extrusive)
Coarse grained (intrusive)
Rhyolite
Granite
Dacite Andesite Basalt
Quartz diorite
Diorite Gabbro PeridotitePegmatite
Sialic/Felsic (acidic)
Intermediate Mafic Ultramafic (basic)
High Ca, Fe, Mg
High SiO , Na, K
2
Pe
rce
nta
ge
of
Min
era
ls b
y V
olu
me
100
80
60
40
20
0
Orthoclase (K) Feldspar
(Microcline)
Na - rich Plagioclase
(Albite)
Plagioclase Feldspars
Ca - rich plagioclase
Pyroxene (Augite)
Amphibole (Hornblende)
Olivine
MuscoviteBiotite
Igneous Rocks Mineral Content
Plutonic Rocks - Structure of Granite
Polished granite section illustrating the mixture of large crystals of different minerals (q = quartz, af = albite feldspar, b = biotite mica
Plutonic Rocks
Granite - quartz, orthoclase, hornblende Granite - quartz, orthoclase, plagioclase, hornblende
Diorite - orthoclase (Na & Ca), hornblende Gabbro - orthoclase (Ca), hornblende, pyroxene
Bowen’s Reaction Series
Correlation of Bowen’s Reaction Series with silicon content, viscosity of lava and relative resistance to chemical weathering
Rock Type
Discontinuous Reaction Series
Continuous Reaction Series
Peridotite (Ultramafic)
Gabro & Basalt (Mafic)
Diorite & Andesite (Intermediate)
Granite & Rhyolite (Sialic/Felsic)
Olivine
Pyroxene
Biotite
Am
phibole
Pla
gioc
lase
Fel
dspa
r
Calcium rich
Sodium rich
Orthoclase (K) Feldspar
Muscovite
Quartz
Ord
er
of
Cry
sta
lliz
ati
on
Tem
pe
ratu
re
Sil
ico
n C
on
ten
t
Vis
co
sit
y
Re
sis
tan
ce
to
Ch
em
ica
l W
ea
the
rin
g
H
L H H H
L L L
Volcanic Rocks - Lavas
Rhyolite (high Si) Andesite
Basalt (high Fe) Basalt - vesicular
More Volcanic Rocks
Sodium Feldspar Basalt (Porphyry) Calcium Feldspar basalt (Porphyry)
Obsidian Volcanic Breccia
Volcanic Breccia - Kelowna
Successive eruptions – Coal seams in between!
Volcanic Rocks - Pyroclasts
Pumice Scoria
Welded Tuff Volcanic bomb - olivine core surrounded by basalt
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