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GY 402: Sedimentary Petrology Lecture 3: Fluid Flow and Sediment Entrainment Instructor: Dr. Douglas W. Haywick UNIVERSITY OF SOUTH ALABAMA
GY 402: Sedimentary Petrology
Lecture 3: Fluid Flow and Sediment Entrainment
Instructor: Dr. Douglas W. Haywick
UNIVERSITY OF SOUTH ALABAMA
Last Tuesday
A) Basic sediment grain size B) Ternary plots (grain size classification) C) Interpreting grain size data (case studies)
D) Grain size parameters (statistics)
Udden-Wentworth grain size (Wentworth, 1922)
Gravel: (>2.00 mm)
Sand: (0.063 mm – 2.00 mm)
Silt: (0.004 mm – 0.063mm)
Clay: (< 0.004mm)
From
: Lew
is, D
.W.,
1984
. Pra
ctic
al S
edim
ento
logy
.van
Nos
trand
Rei
nhol
d, N
ew Y
ork,
229
p.
Sand-Silt-Clay Scheme 1 Folk (1954)
Symbol Index
C-clay; Z-silt; M-mud; S-sand;
sC-sandy clay; sM-sandy mud; sZ- sandy silt;
cS-clayey sand; mS-muddy sand;
zS-silty sand
Symbol Index
C-clay; Z-silt; S-sand;
sC-sandy clay; zS-silty sand; sZ- sandy silt; zC- silty clay
cS-clayey sand; szc-sand-silt-clay;
cZ-clayey silt
Sand-Silt-Clay Scheme 2
Sheppard (1954)
Symbol Index M-mud; G-gravel; S-sand;
sM –sandy mud; mS-muddy sand;
(g)M-slightly gravelly mud; (g)S-slightly gravelly sand;
(g)sM-slightly gravelly sandy mud; (g)mS-slightly gravelly
muddy sand;
gM-gravelly mud; gms-gravelly muddy sand; gS-gravelly sand;
mG-muddy gravel; MsG-muddy sandy gravel; sG sandy gravel
Gravel-Silt-Fines Scheme
Folk (1954)
Descriptive parameters
Source: Blatt, Middleton and Murray (1980)
Roundness (comparison of determination
techniques)
Qua
litat
ive (
Pow
ers,
1953
)
Today’s Agenda
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
Sediment Motion
• Rest (no movement) • Roll • Slide • Saltation (“bouncing”) • Suspension • Mass flow (viscous flow)
What is Viscosity?
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
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
(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!
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!
Enter Stoke’s Law
Stoke’s Law
Vg = gd2(-)
18
Stoke’s Law
Vg = gd2(-)
18
g = gravitational constant (9.8 m/s2)
Stoke’s Law
Vg = gd2(-)
18
g = gravitational constant (9.8 m/s2)
d = particle size diameter (mm)
Stoke’s Law
Vg = gd2(-)
18
g = gravitational constant (9.8 m/s2)
d = particle size diameter (mm)
(sigma) = grain density (g/cm3)
Stoke’s Law
Vg = gd2(-)
18
g = gravitational constant (9.8 m/s2)
d = particle size diameter (mm)
= grain density (g/cm3)
(rho) = fluid density
Stoke’s Law
Vg = gd2(-)
18
g = gravitational constant (9.8 m/s2)
d = particle size diameter (mm)
= grain density (g/cm3)
= fluid density
(mu) = dynamic fluid viscosity
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 = gd2(-)
18
Stoke’s Law
Vg = gd2(-)
18 g is a constant
Stoke’s Law
Vg = gd2(-)
18 g is a constant
= grain density (not a true constant, but…)
Stoke’s Law
Vg = gd2(-)
18 g is a constant
= grain density (not a true constant, but…)
= fluid density (not a true constant, but…)
Stoke’s Law
Vg = gd2(-)
18 g is a constant
= grain density (not a true constant, but…)
= fluid density (not a true constant, but…)
= dynamic fluid viscosity (not a true constant, but…)
Stoke’s Law
Vg kd2
Vg is proportional to grain size
Stoke’s Law
Vg kd2
Vg is proportional to grain size
or, alternatively, grain size is proportional to settling velocity
Stoke’s Law (Graphic Representation)
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)
Actual settling characteristics
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)
Impact Law (Graphic Representation)
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)
Vg = 1.33-
Impact Law (Graphic Representation)
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)
Vg = 1.33-
The result of turbulence and grain interaction as large grains fall through a fluid
Impact Law (Graphic Representation)
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)
Vg = 1.33-
Impact Law (Graphic Representation)
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)
Vg = 1.33-
Impact Law (Graphic Representation)
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)
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)
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
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)
Settling Curve (Graphic Representation)
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)
Settling Curve
(AKA Rubey’s Curve)
Grain Size Analysis
Grain Size Analysis
At 23 oC, all sand and gravel will fall at least 10 cm in 4 minutes, 28 seconds
At 23 oC, all silt, sand and gravel will fall at least 7.5 cm in 5 hours, 43 minutes
Grain Size Analysis
Grain Size Analysis
Sand and gravel are determined via sieving
sand fractions: vc, c, m, f, vf,
gravel fractions: not routinely done
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
Grain Size Analysis
Grain Size Analysis
Grain Size Analysis
Grain Size Analysis
Grain Size Analysis
0.005.00
10.0015.0020.0025.0030.0035.0040.00
grav
el
vc s
and
c sa
nd
m s
and
f san
d
vf s
and
coar
se s
ilt
fine
silt
clay
grain size
wt%
reta
ined
per
sie
ve
Real Fluid Flow & “Entrainment”
Sorry, but we have to talk a bit about physics (and about how airplanes fly)
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)
Entrainment
Deposition
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Traction
Deposition
Suspension
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Grain size = a
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Grain size = a
Entrainment = ae
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Grain size = a
Entrainment = ae
Entrainment velocity = Vae
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Grain size = a
Suspension = as
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Grain size = a
Suspension = as
Suspension velocity = Vas
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Grain size = a
Settling = ad
Settling velocity = Vad
Sediment Entrainment (Hjulstom-Sundborg Diagram)
(from Collinson, J.D. and Thompson, D.B. 1982. Sedimentary Structures. George Allen and Unwin 194p)
Upcoming Stuff
Homework 1) Write 2 Ass. (Hypothesis write up) Due Thursday 11 AM
2) Write 1 Assignment redo (Paper Structure) Due Thursday 11 AM 3) Peer 1 Assignment Due Friday 5 PM
Today’s Lab
Grain Size Analysis
Online Lecture (watch Wednesday): Bed form Development (5)
Thursday Activity
Activity 2: Hand specimens (bring your hand lens)
More!
Writing Assignment 2
Hypothesis
More!
Writing Assignment 2
Methods
Done!
GY 402: Sedimentary Petrology
Lecture 3: Fluid Dynamics
Instructor: Dr. Doug Haywick [email protected]
This is a free open access lecture, but not for commercial purposed. For personal use only.
