gy 402: sedimentary petrology - university of south alabama(from collinson, j.d. and thompson, d.b....
TRANSCRIPT
GY 402: Sedimentary Petrology
Lecture 4: Sedimentary Rock Classification
Instructor: Dr. Douglas W. Haywick
UNIVERSITY OF SOUTH ALABAMA
Last Time (in class)
1. Six modes of sediment movement 2. Real simple fluid dynamics (ideal conditions)
3. Initiation of sediment movement 4. Nasty mathematical relationships (Shield’s Diagram)
5. Useful empirical relationships (Hjulstrom’s Diagram)
Sediment Motion
• Rest (no movement) • Roll • Slide • Saltation (“bouncing”) • Suspension • Mass flow (viscous flow)
Modes of Viscous Flow
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Ideal Fluid Flow
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Ideal Fluid Flow (f
rom
Col
linso
n, J
.D. a
nd T
hom
pson
, D.B
. 198
2. S
edim
enta
ry S
truct
ures
. Geo
rge
Alle
n an
d U
nwin
194
p)
This cartoon is critical and is the basis for grain size analysis!
Stoke’s Law
Vg = gd2(-)
18
g = gravitational constant (9.8 m/s2)
d = particle size diameter (mm)
= grain density (g/cm3)
= fluid density
= dynamic fluid viscosity
Vg = settling velocity
Stoke’s Law
Vg kd2
Vg is proportional to grain size
Composite curves (Stoke’s + Impact)
10-4 10-3 10-2 10-1 100 101 102 103
103
102
101
100
10-1
10-2
log d (mm)
log
Vg
(cm
/s)
Laminar flow
Turbulent flow
Grain Size Analysis
Sand and gravel are determined via sieving
sand fractions: vc, c, m, f, vf,
gravel fractions: not routinely done
Analysis done using simple excel spread sheet (will be available on departmental computers and/or e-mailed to you)
Grain Size Analysis
Fluid Flow & “entrainment”
(from Blatt, H, Middleton, G. and Murray, R., 1980. Origin of Sedimentary Rocks. Prentice Hill, 782 p)
Entrainment is synonomous with: “initiation of grain movement”
Sediment Entrainment
(from Blatt, H, Middleton, G. and Murray, R., 1980. Origin of Sedimentary Rocks. Prentice Hill, 782 p)
Shear Velocity
Sediment Entrainment (Shield’s Diagram)
(from Blatt, H, Middleton, G. and Murray, R., 1980. Origin of Sedimentary Rocks. Prentice Hill, 782 p)
Sediment Entrainment (Hjulstom’s Diagram)
(from Blatt, H, Middleton, G. and Murray, R., 1980. Origin of Sedimentary Rocks. Prentice Hill, 782 p)
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Today’s Agenda 1. Why bother with sedimentary classification? 2. Siliciclastic sedimentary rock schemes 3. Volcaniclastic sedimentary rock schemes 4. Carbonate rock schemes
1.5 mm FOV, PPL
Siliciclastic Rock Classification
1.5 mm FOV, PPL
Particle size classification = energy of deposition
Siliciclastic Rock Classification
1.5 mm FOV, PPL
Particle size classification = energy of deposition
Grain type classification
= origin of sediment
Orthoclase
Porosity
Lithic
Quartz
Siliciclastic Rock Classification
1.5 mm FOV, PPL
Particle size classification = energy of deposition
Grain type classification
= origin of sediment
The Problem: Sedimentary rocks come in more “flavors” than any other type of rock.
How do you classify all of them?
Siliciclastic Rock Classification
Sedimentary Rock Classification
Grain size specific and/or…
Sedimentary Rock Classification
Grain size specific and/or… Particle type specific (e.g. need specific schemes for major
sedimentary rocks classes)
Sedimentary Rock Classification
Particle type specific 1. Siliciclastic sedimentary rocks (Quartz, Feldspars, Clays,
Lithic Fragments, Micas, etc.)
2. Shales and Mudstones (grain to “matrix” content)
3. Volcaniclastic sedimentary rocks (vitric fragments and ash, phenocrysts, lithics )
4. Carbonate sedimentary rocks (skeletal grains, non-skeletal grains and matrix)
5. Organic sedimentary rocks (kerogen content, coal grade etc.)
Siliciclastic Sedimentary Rocks
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
(Arenites)
Siliciclastic Sedimentary Rocks
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
(Arenites)
Siliciclastic Sedimentary Rocks
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
(Arenites)
GY 402 seal of approval
Siliciclastic Sedimentary Rocks
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
Siliciclastic Sedimentary Rocks
>75% mud matrix
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
Mudstone
Siliciclastic Sedimentary Rocks
15 to 75% mud matrix
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
Wackes
Siliciclastic Sedimentary Rocks
<15% mud matrix
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
Arenites
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Siliciclastic Sedimentary Rocks
Q = Quartz + chert (sometimes)
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments + chert (usually)
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
Sediment apron
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
2 cm
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
2 cm
an “F” grain
(microcline)
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
2 cm
an “F” grain (albite)
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
2 cm
a “Q” grain
Siliciclastic Sedimentary Rocks
Q = Quartz
F = Feldspars (orthoclase + plagioclase)
R/L = Lithic Fragments
Granite mountain
2 cm
an “R” grain
Volcaniclastic Sedimentary Rocks
Carbonate Sedimentary Rocks
Source: Blatt, H., Middleton, G and Murray, R., 1980: Origin of Sedimentary Rocks. Prentice Hill, 782 p.
Folk Classification Scheme
Carbonate Sedimentary Rocks
GY 402 seal of approval
Source: Prothero, D.R. and Schwab, F., 1996. Sedimentary Geology. W.H. Freeman, 575 p.
Carbonate Sedimentary Rocks
Equivalent to sandstone/mudstone in siliciclastic rock schemes
Source: Prothero, D.R. and Schwab, F., 1996. Sedimentary Geology. W.H. Freeman, 575 p.
Carbonate Sedimentary Rocks
Equivalent to conglomerates in siliciclastic rock schemes
Source: Prothero, D.R. and Schwab, F., 1996. Sedimentary Geology. W.H. Freeman, 575 p.
Carbonate Sedimentary Rocks
No equivalents in siliciclastic rock schemes
Source: Prothero, D.R. and Schwab, F., 1996. Sedimentary Geology. W.H. Freeman, 575 p.
Upcoming Stuff
Homework 1) Write 2 Ass. (Hypothesis write up) Due Thursday
2) Write 1 Assignment redo (Paper Structure) Due Thursday 3) Peer 1 Assignment Due Tomorrow
Today’s Lab
Grain Size Analysis (First column run starts at 12:30: BE THERE!)
Next Lecture: Bed form Development (5)
Writing Assignment 2 Part 1: Hypothesis and Test
Writing Assignment 2 Part 2: Methods
GY 402: Sedimentary Petrology
Lecture 4: Classification of Sedimentary Rocks
Instructor: Dr. Doug Haywick
This is a free open access lecture, but not for commercial purposed. For personal use only.