Outline:

1
ERTH 2002 LABORATORY COMPONENT
Outline Weeks 1-3 LABS IR-1 to IR-3, Igneous
Rocks Weeks 4-6 LABS MR-1 to MR-3, Metamorphic
Rocks Weeks 7-9 LABS SR-1 to SR-3, Sedimentary
Rocks Weeks 10-11 LABS OM-1 to OM-2, Ore
Microscopy Final weeks Lab project completion
2
ERTH 2002 LABORATORY COMPONENT
What to bring to labs Lab Manual - available in
department office (5.50) - you should also
consider bringing your ERTH 2001 manual for
the first few weeks, until you are fully
comfortable with optical property tests Nesse -
you will need this for mineral ID Hand lens -
hand samples as well as thin sections are
included for most samples Appendix
1 of lab manual includes lists of common mineral
associations with room to write in key optical
properties - you are advised to fill this
in at your earliest opportunity
3
ERTH 2002 LABORATORY COMPONENT
Petrography Description and classification of
rocks based on observations in hand sample and
thin section. Involves - mineralogy - texture
- classification
4
ERTH 2002 LABORATORY COMPONENT
Petrography Description and classification of
rocks based on observations in hand sample and
thin section. Involves - mineralogy - you
already know how to identify minerals
now you need lots of
practice!!!
5
ERTH 2002 LABORATORY COMPONENT
Petrography Description and classification of
rocks based on observations in hand sample and
thin section. Involves - mineralogy - you
already know how to identify minerals
now you need lots of
practice!!! - texture - relationships between
minerals (new to you) fundamentally important
to rock identification and interpretation
6
ERTH 2002 LABORATORY COMPONENT
Petrography Description and classification of
rocks based on observations in hand sample and
thin section. Involves - mineralogy - you
already know how to identify minerals
now you need lots of
practice!!! - texture - relationships between
minerals (new to you) fundamentally important
to rock identification and interpretation -
classification - assigning an appropriate name to
a rock (mainly) new to you involves aspects of
both mineralogy and texture
7
ERTH 2002 LABORATORY COMPONENT
Introduction to Petrography of Igneous Rocks
(Lab Manual, p.4-29) Igneous Minerals (p.
5-6) Igneous Textures (p. 7-14) Igneous
Classification (p. 15-21) LAB IR-1 Ultramafic
and Mafic Rocks (p. 24-25) LAB IR-2 Intermediate
and Felsic Rocks (p. 26-27) LAB IR-3 Fragmental
Igneous Rocks (p. 28-29)
8

ERTH 2002 LABORATORY COMPONENT
1. Getting started .... review broad categories
of igneous rocks (p. 4)
look up definitions and fill in the table
9
ERTH 2002 LABORATORY COMPONENT
2. Igneous Minerals .... systematic variation in
mineralogy with rock type main basis for
classification
felsic intermediate
mafic ultramafic
10

ERTH 2002 LAB IR-2
2. Igneous Minerals .... systematic variation in
mineralogy with rock
type main basis for classification
11

ERTH 2002 LAB IR-2
2. Igneous Minerals .... systematic variation in
mineralogy with rock
type main basis for classification
Lab IR-1
Lab IR-2
felsic intermediate
mafic ultramafic
light coloured dark
coloured
12

ERTH 2002 LAB IR-2
2. Igneous Minerals .... systematic variation in
mineralogy with rock
type main basis for classification
felsic intermediate
mafic ultramafic
light coloured dark
coloured
13

ERTH 2002 LAB IR-2
2. Igneous Minerals .... systematic variation in
mineralogy with rock
type main basis for classification
Lab IR-1
Lab IR-2
felsic intermediate
mafic ultramafic
light coloured dark
coloured
14

ERTH 2002 LAB IR-2
2. Igneous Minerals .... systematic variation in
mineralogy with rock
type main basis for classification
why 2 names?
felsic intermediate
mafic ultramafic
light coloured dark
coloured
15

ERTH 2002 LABORATORY COMPONENT
Rocks with same mineralogy may be given different
names depending on whether they are intrusive or
extrusive, and which type of each......
How can you tell which is which? TEXTURES!!!
16

ERTH 2002 LABORATORY COMPONENT
systematic petrographic descriptions (any
rock) always work from larger scale to smaller
scale..... outcrop hand sample thin section
(low power to high power)
17

ERTH 2002 LAB IR-1
For igneous rocks..... outcrop intrusive vs
extrusive? hand sample crystallinity? grain
size? phenocrysts? banding? fragments? thin
section minerals? groundmass? relationships
between crystals?
18

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks relatively dark coloured main minerals
olivine, pyroxene, calcic plagioclase both
intrusive and extrusive varieties
included textures to observe (increasing
detail) crystallinity granularity crystal
shapes relationships between crystals

19

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Crystallinity glass vs
crystals Granularity relative and absolute
grain size Crystal shapes quality of crystal
face development 3-D shape (habit) specific
terms may apply Relationships between
crystals lots of possibilities details covered
in lab
20

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Crystallinity glass vs crystals
IR-6 holohyaline
IR-1holocrystalline
IR-5 hypocrystalline / hypohyaline
21

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Granularity relative and absolute grain
size
1 mm
1 mm
IR-1 phaneritic coarse-grained equigranular
IR-5 aphanitic fine-grained inequigranular porphy
ritic
22

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Crystal shapes quality of crystal face
development 3-D shape (habit) specific terms
may apply
1 mm
1 mm
IR-1 subhedral to anhedral equant
IR-5 euhedral to subhedral equant, tabular
23

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Crystallinity glass vs
crystals Granularity relative and absolute
grain size Crystal shapes quality of crystal
face development 3-D shape (habit) specific
terms may apply Relationships between
crystals lots of possibilities details covered
in lab
24

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Classification IUGS system relative
abundance (modal ) of specific minerals includes
QAP diagram introduced last term different
diagrams for different mineral combinations differ
ent diagrams for intrusive vs extrusive rocks 1.
intrusive vs extrusive? (pyroclastic?) 2. quartz
- alkali feldspar - plagioclase (QAP) or
feldspathoid - alkali feldspar - plagioclase
(FAP)? 3. "crowded corner"? (not much Q, A, or
F) 4. pyroclastic? (LAB IR-3)
25

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Classification IUGS system details
in manual p. 15-21
QAP (you saw this last term)
FAP (same idea but with feldspathoid instead of
quartz)
felsic to intermediate plutonic rocks
26

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Classification IUGS system details
in manual p. 15-21
the "crowded corner"
most (ultra)mafic rocks contain little or no
quartz, alkali feldspar, or feldspathoid in
terms of QAP-FAP, P 100!
felsic to intermediate plutonic rocks
27

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous
Rocks Classification IUGS system
mafic rocks plagioclase-pyroxene- olivine
manual, p. 19 note - these are conventional
triangular diagrams!!! names given are
for plutonic rocks consult manual for names of
volcanic equivalents
ultramafic rocks (lt10 plag) orthopyroxene- clino
pyroxene- olivine
28

ERTH 2002 LAB IR-1
LAB IR-1 Ultramafic and Mafic Igneous Rocks Lab
format Labs IR-1-3, MR-1-3 1. checklist (5
samples, 5 minerals, 5 textures) - info for 1-2
samples will be filled out at the
beginning of each lab 2. description sheet (1 or
2 samples) - systematic description and
classification Checklist must be completed and
checked before you leave the lab both checklist
and description sheet(s) are handed in at the
beginning of the following lab
29

30

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Lab IR-1
Lab IR-2
felsic intermediate
mafic ultramafic
light coloured dark
coloured
31

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
relatively light coloured (lt 50 dark
minerals) main minerals Na-Ca plagioclase,
K-feldspar, quartz hornblende, bitoite,
muscovite both intrusive and extrusive varieties
included textures to observe (increasing
detail) crystallinity granularity crystal
shapes relationships between crystals

32

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Crystallinity glass vs crystals Granularity
relative and absolute grain size Crystal shapes
quality of crystal face development 3-D shape
(habit) specific terms may apply Relationships
between crystals lots of possibilities details
covered in lab
33

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Crystallinity glass vs crystals
IR-6 (f.o.v. 6.25 mm) essentially holohyaline
34

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Crystallinity glass vs crystals
IR-10 (f.o.v. 6.25 mm) holocrystalline
35

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Granularity relative / absolute grain size
IR-6 (f.o.v. 6.25 mm) aphanitic a few
fine-grained phenocrysts inequigranular, sparsely
porphyritic
IR-10 (f.o.v. 6.25 mm) phaneritic very
coarse-grained inequigranular
36

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Crystal Shape
IR-6 (f.o.v. 2.5 mm) radiating
spherulites euhedral phenocrysts
IR-10 (f.o.v. 6.25 mm) most crystals subhedral,
tabular some euhedral, some anhedral
37

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks
Relationships between crystals
IR-10 (6.25 mm)
perthitic texture plagioclase exsolution
lamellae in K-feldspar host
IR-6 (f.o.v. 6.25 mm) xenolith aggregate of
crystals foreign to rock
myrmekitic texture irregular intergrowth of
quartz and feldspar
IR-10 (2.5 mm)
38

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous
Rocks Classification
QAP
quartz-bearing very common
IUGS system plutonic rocks - p. 18 volcanic
rocks - p. 20
overlap
feldspathoid- bearing relatively rare
FAP
39

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous
Rocks Classification
QAP
quartz-bearing very common
IUGS system plutonic rocks - p. 18 volcanic
rocks - p. 20
feldspathoid- bearing relatively rare
FAP
40

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous
Rocks Classification
QAP
quartz-bearing very common
IUGS system plutonic rocks - p. 18 volcanic
rocks - p. 20
FAP
41

ERTH 2002 LAB IR-2
Felsic and Intermediate Igneous Rocks Lab format
Labs IR-1-3, MR-1-3 1. checklist (5 samples, 5
minerals, 5 textures) - info for 1-2 samples
will be filled out at the beginning
of each lab 2. description sheet (1 or 2
samples) - systematic description and
classification - checklist must be completed and
checked before you leave lab - both checklist
and description sheet(s) are handed in at
the beginning of the following lab
42

43

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
contain fragments of "foreign" rocks or crystals
incorporated into magma during ascent and/or
emplacement (xenoliths, xenocrysts) ......or....
.. consist partly or entirely of fragments
formed during explosive eruptions and/or their
reworked equivalents (pyroclastic rocks) highly
heterogeneous contain pieces that "don't belong"
44

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks span compositional range
Lab IR-3
felsic intermediate
mafic ultramafic
light coloured dark
coloured
45

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
span compositional/ colour range
intermediate-felsic rocks more likely to be
associated with explosive volcanism (high
viscosity magmas) both intrusive and extrusive
varieties possible distinguish between
xenoliths, xenocrysts (mainly in intrusive rocks)
and pyroclastic fragments (extrusive rocks)
46

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
distinguish between xenoliths, xenocrysts (mainly
in intrusive rocks) and pyroclastic fragments
(extrusive rocks) xenoliths/xenocrysts -
host rock has magmatic texture (volcanic/plutonic)
(e.g., interlocking grains, homogeneous
groundmass) - rock/crystal fragments show
evidence of reaction with host magma (e.g.,
reaction rims, embayed crystals)
47

incorporation of xenoliths and xenocrysts into
plutonic and hypabyssal rocks
kimberlite pipe (diatreme)
48

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
distinguish between xenoliths, xenocrysts (mainly
in intrusive rocks) and pyroclastic fragments
(extrusive rocks) xenoliths/xenocrysts
IR-6 (Lab 2) xenolith in glassy matrix (PPL fov
2.5 mm)
IR-11 (Lab 3) xenocryst in porphyritic
matrix (PPL fov 2.5 mm)
49

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
distinguish between xenoliths, xenocrysts (mainly
in intrusive rocks) and pyroclastic fragments
(extrusive rocks) pyroclastic fragments -
rock consists largely of fragments (rock, glass,
crystal fractured,
non-interlocking, irregular outlines) -
heterogeneous with respect to size, shape,
composition of fragments -
substantial proportion of volcanic fragments
(typically highly vesicular, glassy)
- may show evidence of welding (flattening
following deposition while rock
still hot)
50

Fragmental Volcanic Rocks range of eruption
styles and magma compositions possible
ash flow eruption, Mt. St. Helen's 1980
aa flow, Hawaii
scoria (cinder) cone, Iceland
51

styles of explosive eruptions producing
pyroclastic rocks
ignimbrite (welded ash flow deposit) Chiricahua
Mtns, Arizona
52

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
distinguish between xenoliths, xenocrysts (mainly
in intrusive rocks) and pyroclastic fragments
(extrusive rocks) pyroclastic fragments
IR-14 pumice fragments flattened around rock
and crystal fragments (PPL fov 6.25 mm)
IR-15 heterogeneous assemblage of rock and
crystal fragments (PPL fov 6.25 mm)
53

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks
Crystallinity fragments can consist of glass
(vitric), single crystals (crystal), or crystal
aggregates (lithic) Granularity variable
relative/absolute size of fragments
(pyroclastic rocks) Crystal shapes euhedral
crystals less common - xenocrysts - react with
magma - pyroclastic crystals -
broken Relationships between crystals lots of
possibilities details covered in lab
54

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks Classification
if fragments are xenoliths/xenocrysts in
otherwise homogeneous volcanic or plutonic rock,
classify host rock as usual (Labs 1-2), ignoring
fragments
IUGS system pyroclastic rocks - p. 20
1. grain size of fragments bombs - lapilli
- ash 2. types of fragments lithic - vitric
- crystal (not specified in Manual - attempt to
estimate relative of each)
55

ERTH 2002 LAB IR-3
Fragmental Igneous Rocks Classification
Lab format Labs IR-1-3, MR-1-3 1. checklist (5
samples, 5 minerals, 5 textures) - info for 1-2
samples will be filled out at the
beginning of each lab 2. description sheet (1 or
2 samples) - systematic description and
classification 2 worksheets this week 1 of them
with a written description (paragraph form) -
checklist must be completed and checked before
you leave lab - both checklist and description
sheet(s) are handed in at the beginning of the
following lab