A Watery Grave for the Urey Ratio Paradox?
CIDER group: J. Crowley, M. Gérault, T. Höink, A. Schaeffer, P. Barry, M. Hirschmann, T.
Becker, S. Hier-Majumder, R. O’Connell, J. Frost, J. Girard, M. Nunez-Valdez
Volatiles
Melting
Warm Mantle
Cold Plate
Hydrated Layer
Dehydrated Lithosphere
Mantle
Heat Flow
Volatiles
Water and Plate Tectonics
Water may affect plate mantle dynamics by
1 - Lubricating subduction zone faults
2 - Creating strong plates through
dehydration of the lithosphere
3 - Modifying mantle viscosity
Consider the cooling and thermal evolution of a
simple ‘Earth-like’ planet with plate tectonics and a
water dependent rheology
Heat and Water Transport by Plate Tectonics
Degassing
Heat Flow
Regassing
Internal
Heating
Melting
Mantle Temperature
Water Concentration
Viscosity
Heat and Water Transport by Plate Tectonics
Feedbacks
Degassing
Heat Flow
Regassing
Internal
Heating
Melting
Mantle Temperature
Water Concentration
Viscosity
Heat and Water Transport by Plate Tectonics
Feedbacks
Degassing
Heat Flow
Regassing
Internal
Heating
Melting
Mantle Temperature
Water Concentration
Viscosity
Effect of water dependence
Effect of temperature dependence
J. Crowley, M. Gérault, and R. O’Connell, EPSL (2011)
Relative Effect of Water and Thermal Cycles
Time Scale Analysis:
Feedbacks and relative rates of change
require system to evolve such that
(Theory)
(In agreement with Observation
for present day Earth)
J. Crowley, M. Gérault, and R. O’Connell, EPSL (2011)
Relative Effect of Water and Thermal Cycles
Time Scale Analysis:
Feedbacks and relative rates of change
require system to evolve such that
(Theory)
Implications:
Cooling + Regassing
(In agreement with Observation
for present day Earth)
Regassing-Degassing
Rheology
Cooling + Degassing
Warming + Degassing
Heat and water transport are
coupled
Feedback needs to be
included in thermal evolutions
Warming + Regassing
Surface Heat Flow
A net regassing of the mantle forces
the thermal cycle to release heat faster
Regassing reduces the Urey ratio
J. Crowley, M. Gérault, and R. O’Connell, EPSL (2011)
Now Apply to the Earth
J. Crowley, M. Gérault, T. Höink, A. Schaeffer, P. Barry,
T. Becker, M. Hirschmann, S. Hier-Majumder, and R. O’Connell
Temperature and water dependent rheology
More accurate parameterization of degassing and
regassing fluxes
New dynamic model for thermal evolution that
includes effects of strong plates and depth
dependent viscosity
Modeling of multiple reservoirs (surface, upper and
lower mantle, and transition zone)
Link Between Past and Present Earth
2200
200
Classic Thermal
Evolutions
180
2000
160
140
Heat Flow (TW)
Temperature (C)
1800
1600
1400
120
100
80
60
40
1200
Inte
r
nal H
20
1000
0
1
2
3
Time (Gy)
4
0
0
1
2
3
Time (Gy)
eatin
g
4
Link Between Past and Present Earth
2200
200
No Water Dependence
Water Dependent Viscosity 180
2000
160
Thermal Evolutions
with Water
140
Heat Flow (TW)
1800
Temperature (C)
Classic Thermal
Evolutions
1600
1400
120
100
80
60
40
1200
Inte
r
nal H
20
1000
0
1
2
3
Time (Gy)
4
0
0
1
2
3
Time (Gy)
eatin
g
4
Link Between Past and Present Earth
2200
200
No Water Dependence
Water Dependent Viscosity 180
2000
160
Thermal Evolutions
with Water
140
Heat Flow (TW)
1800
Temperature (C)
Classic Thermal
Evolutions
1600
1400
120
100
80
60
40
1200
Inte
r
nal H
20
1000
0
1
2
3
Time (Gy)
4
0
0
1
2
3
Time (Gy)
eatin
g
4
New mechanism allowing for a large range of possible Urey ratios
Dynamics of present day Earth tell us about the past - possibly ‘deep time’
Feedback on CIDER
• smaller groups...
• have all groups meet throughout the year
89723(7*+CD:E2?F*+G23*+,HF;./
&!
&!
&!
&!
&"
!
&B
A
"
#
'()*+,-./
#
'()*+,-./
$
$
%
,Q/
SMS5
&&
&!
%
=2N3
5997(?F
!
!IJ
!
!
"
"
"
#
'()*+,-./
#
'()*+,-./
61*N*?3
O2.
$
$
%
,*/
&IJ
&
%
&!
&!
&!
&!
&
&
!
O*F2NN(?F
G*F2NN(?F
61*N*?3
O2.
<*23+=79>+;+-*?*123(9?+,'@/
O*F2NN(?F
G*F2NN(?F
&
!
61*N*?3
O2.
"
&!
&!
O*F2NN(?F
G*F2NN(?F
L79>
5997(?F
6723*+8*79:(3.+,:);.*21/
&$!!
"
K2?37*+@23*1+59?:*?3123(9?+,00)/
!
&!
61*N*?3
O2.
&#!!
KL;KL,3M#I$-./
&%!!
61*N*?3
O2.
"!!!
O*F2NN(?F
G*F2NN(?F
&!
61*N*?3
O2.
&!!!
O*F2NN(?F
G*F2NN(?F
&"!!
O*F2NN(?F
G*F2NN(?F
'*)0*12341*+,5/
,2/
,P/
,:/
"
"
B
"
#
'()*+,-./
,R/
"
#
'()*+,-./
$
%
$
%
J. Crowley, M. Gérault, and R. O’Connell, EPSL (2011)
New Work:
- Sensitivity to rheology 350
7.8
7.75
7.7
7.65
7.6
0.6
0.8
r
1
10
5
0
0
200
400
Activation Energy E (kJ/kg mol)
250
30
25
0.8
r
1
20
0.6
1.2
340
Mantle Water Concentration (ppm)
Plate Velocity (cm/year)
20
15
300
200
0.6
1.2
0.69
35
Urey Ratio
7.85
Surface Heat Flow
Internal Heating
320
300
280
260
240
220
200
0
200
400
Activation Energy E (kJ/kg mol)
0.68
0.67
0.66
0.8
r
1
1.2
0.65
0.6
50
0.8
r
1
1.2
0.8
Surface Heat Flow
Internal Heating
0.7
40
30
20
10
0.6
Urey Ratio
7.9
Heat Flow (TW)
Plate Velocity (cm/year)
7.95
40
Heat Flow and Internal Heating (TW)
Mantle Water Concentration (ppm)
8
0.5
0.4
0.3
0.2
0.1
0
0
200
400
Activation Energy E (kJ/kg mol)
0
0
200
400
Activation Energy E (kJ/kg mol)
Relative Effect of Water and Heat Transport on Viscosity
E, r
Ur
Rnet
0.5
0.5
0.5
0.5
0.5
0.5
0.25
0.75
0.5
0.5
r
χm
#
kJ
mol
300
300
300
500
300
500
300
300
300
300
$
300
600
900
300
300
300
300
300
300
300
re
n
St
SW T
(ppm)
0.68
0.68
0.68
0.68
1
1
0.68
0.68
0.68
0.68
gt
h
tr
at
io
E
Re
lat
ive
rC
W
at
e
rE
on
c
on
xp
n
at
io
en
en
rg
χm
±9
±9
±9
±9
±9
±9
±9
±9
±6
±3
Ur
W
at
e
!R − D"
1011 kg
yr
tiv
Relative Effect for
Present Day Earth
(Observation)
Ac
Re
ga
ss
D ing
eg
as
sin
g
U
re
y
Ra
tio
En
e
Effect of temperature dependence
J.W. Crowley, M. Gérault, and
R.J. O’Connell, EPSL (2011)
t
y
n
Effect of water dependence
1.3
0.57
0.34
0.80
2.0
1.2
0.89
2.7
0.89
0.44