Soils - Igneous Parent Material

Soils - Igneous Parent Material - ROCK
CYCLE
...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ROCK
CYCLE
 IGNEOUS
ROCK
 Granite
 
 h*p://web.uct.ac.za/depts/geolsci/dlr/rocks/gran9.jpg •  VIOOLSDRIF
BATHOLITH
SA
‐
A
1900
Ma
 •  ADAMELLITE
(Two
Feldspar
Granite):
Orthoclase
(phenocrysHc)
‐
 Plagioclase
‐
Quartz
‐
BioHte
‐
MagneHte
 ROCK
 •  a
solid
aggregate
of
 one
or
more
 minerals
or
 mineral‐like
 substances.
 –  Miracle
Rock
 Colorado
 IGNEOUS
ROCKS
 •  rocks
which
are
formed
 from
molten
rock.
 •  LaHn

 –  "ignis"


fire
 IGNEOUS
ROCKS
 •  Of
the
topmost
30
miles
of
the
crust
(50km)
 95%
are
igneous
rocks.
 Magma
 •  melt
+
VolaHles
+
solid
components
 MAGMA
 •  Melt
+
VolaHles
+
Solid
component
 LAVA
 •  Magma
at
the
surface
 Lava
 •  Up
to
60
mph
 •  Slows
as
it
 cools
 •  Will
burn
 anything
in
 its
path
 Lava
 •  Red
hot
‐
molten
 •  Black
‐
cooler
 –  SHll
hot!
 –  600
cenHgrade
 Lava
 •  Days
to
months
to
solidify
 •  igneous
rocks
make
up
all
the
oceanic
crust

 •  much
of
the
conHnental
crust

 "freezes”
‐
at
over
650
degrees
cenHgrade

 INTRUSIVE
or
PLUTONIC
rocks
 •  Igneous
rocks
that
 cool
in
pre‐exisHng
 rocks

 •  PLUTO
‐
Greek
 God
of
the
 Underworld
 EXTRUSIVE
or
VOLCANIC
rocks
 •  Igneous
rocks
that
 cool
on
the
surface
 of
the
Earth

 •  VULCAN,
Roman
 God
of
Fire
 Extrusive
rock
 PyroclasLc

 





























“pyro”
‐
fire
 

































pyromania
 
 
 
 
 
clast
‐
fragment
 Volcanic
ash
 •  Moves
downslope
due
to
gravity
 •  water
can
make
 this
a
mud
flow
‐
 can
be
very
 dangerous
 IGNEOUS
ROCKS
CLASSIFIED
BY
COMPOSITION
 •  4
main
types
of
magma
 •  based
on
the
amount
of
Silica

 –  Si
(silicon)
and
O
(oxygen)
 –  
weight
%
SiO2

 –  +
iron
oxides
and
magnesium
oxifes
 –  FeO
and
MgO

 Felsic
 •  66
‐
77%
silica
 •  Light
colored
minerals
are
oien
rich
in
potassium
(K),
 Sodium
(Na)
and
(Ca)
and
richer
in
silicon
(Si).

 •  Usually
has
abundant
potassium
feldspar
 •  FELSIC
‐
"fel"dspar
and
"si"li"c"a
 FELSIC
 •  minerals

 –  
 quartz

 –  feldspar

 –  muscovite

 –  bioHte
(small
amount)
 Granite
‐
conHnents
 MAFIC
 •  45‐52%
Silica

 •  Dark
colored
minerals
are
oien
rich
in
iron
 (Fe)
and
magnesium
(Mg)
 •  MAFIC
‐
"Ma"gnesium
and
"F"e
‐
iron
and
 sil"ic"a"
 Dark
colored
minerals
 •  olivine
 •  Pyroxene
 –  augite
 •  amphibole
 –  hornblende
 •  BioHte
 MAFIC
rocks
 typical
of
oceans
 •  BASALT
is
a
fine
grained,
black
igneous
rock.
 •  GABBRO
coarse
grained
 INTERMEDIATE
 •  
52‐66%
Silica

 •  light
and
dark
minerals
"salt
and
pepper”

 •  between
felsic
and
mafic

 INTERMEDIATE
 •  Minerals

 –  Na
plagioclase
 –  Mica

 –  Pyroxene
–
augite

 –  amphibole
‐
hornblende
 –  maybe
a
li*le
quartz
 INTERMEDIATE
 •  Dominantly
on
the
conHnents
 ULTRAMAFIC
 •  less
than
38%
silica

 •  mainly
dark
minerals

 •  more
Fe
and
Mg
rich
than
mafic

 ULTRAMAFIC
 •  Minerals

 –  olivine

 –  Pyroxene
 –  NO
QUARTZ
 ULTRAMAFIC
 •  PERIDOTITE
coarse
grained

 –  70‐90%
olivine
 •  Mainly
in
the
mantle
 ...
View Full Document

This note was uploaded on 01/23/2012 for the course GEOL 306 taught by Professor Staff during the Spring '08 term at George Mason.

Ask a homework question - tutors are online