1
[
Geophysical Research Letters
]
Supporting Information for
A Giant Impact Origin for the First Subduction on Earth
Qian Yuan
1,2
*, Michael Gurnis
2
, Paul D. Asimow
1
, Yida Li
2
1
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California CA 91125,
USA.
2
Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125, USA
Corresponding author: Qian Yuan (qyuan@caltech.e
du)
Contents of this file
Figures S1 to
S
7
Tables S1
to S2
2
Fig
ure
S1.
Additional model results with influence of various model parameters compared
to the 2D reference case. Panel
(a)
represents the viscosity of the piles is decreased by a
factor of 10. In panel (b) a 5 times higher reference viscosity was used. Panel (c)
incorporates a higher temperature
-
dependent viscosity. Panel
(
d
)
illustrates a scenario with
relatively less dense L
LSVP materials, while Panel
(
e
)
represents a case with even denser
LLSVP materials. In panel
(
f
)
, the LLSVP materials has a stronger depth
-
dependent
density
.
3
Fig
ure
S
2
.
Additional models showing the effect of different ages of the initial
lithosphere
and weakening rates
. From panel
(a)
to
(
c
)
, the lithosphere age is initially 25 Myr, 75 Myr
and 100 Myr, respectively.
The
reference plastic strain
in panels (d) and (e) are 0.5 and 1,
respectively, resulting in faster yielding and more extens
ive plastic failure
. Panel (f) use
s
a
periodic boundary and doubled resolution compared to the 2D reference case.
4
Fig
ure
S
3
.
Viscosity and temperature field of an
a
dditional model with aspect ratio of
model
of 5
compared to the 2D reference case
.
5
Fig
ure
S
4
.
Temporal evolution for the viscosity
(first row), compositional (second row)
and temperature (third row)
field of the 3D case
with a higher yield strength (
80
MPa) of
the lithosphere showing a segment of the lithosphere was broken and subduc
ted.
6
Fig
ure
S
5
.
Temporal evolution for the
viscosity (first row), compositional (second row)
and temperature (third row)
field of the 3D case
with a higher yield strength (100 MPa) of
the lithosphere showing
plume failing to induce subduction.
7
Fig
ure
S
6
.
Temporal evolution for the
temperature
(first row)
and
viscosity
(second row)
field of the 3D case
with
out LLSVP materials
showing
plume can induce subduction
with
a higher yield strength (100 MPa) of the lithosphere.
8
Fig
ure
S
7
.
Temporal evolution for the
viscosity (first row), compositional (second row)
and temperature (third row)
field
of the 3D case with a CMB
temperature of
3
,
773 K
showing plume failing to induce subduction.
9
Table S1.
Model parameters
used in the numerical
experiments
.
Symbol
Definition
Value
퐷
Mantle thickness
2,890 km
훼
Thermal expansivity
3
́
10
–
5
K
–
1
푘
Thermal diffusivity
2
́
10
–
6
m
2
·
s
–
1
푛
Non
-
Newtonian exponent
3
퐸
Activation energy
540 k
J
mol
–
1
휂
()*
Maximum viscosity
10
25
Pa s
휂
(+,
Minimum viscosity
10
18
Pa s
휇
Shear modulus
3
́
10
10
Pa s
휀
/
̇
Reference strain rate
10
–
15
s
–
1
푇
/
Surface temperature
273 K
푇
2
Mantle temperature
1
,
673 K
푇
345
Core
-
mantle boundary temperature
3
,
2
73K
to
5
,
273 K
퐻
Internal
heating rate
for LLSVPs
8
.
3
×
10
−
7
W
·
m
−
3
휏
8
/
Maximum yield stress
6
0
to
1
8
0
M
P
a
휏
89
Minimum yield stress
3 M
P
a
휀
:
/
Reference plastic strain
0.5
to
2
ℎ
Mafic crust thickness
30 km
퐶
/
Initial cohesion
44 M
P
a
휇
8
/
Initial friction coefficient
0.6
휌
>>?@:
Density anomaly of LLSVPs at CMB
1
%
,
3
%
휌
Reference density
3,300 kg/m
3
10
Table S2.
Comparison of the heat
-
producing elements models between the bulk silicate Mars and
Earth.
K (ppm)
U(ppm)
Th (ppm)
References
Mars
360
0.018
0.068
Yoshizaki and McDonough
(
2020
)
Mars
305
0.016
0.056
Wänke and Dreibus (1994)
Mars
309
0.016
0.058
Taylor (2013)
Mars
76.5
0.035
0.125
Morgan and Anders (1979)
Mars
920
0.016
0.055
Lodders and Fegley (1997)
Mars_average
394.1
0.0202
0.0724
Earth
180
0.018
0.064
Taylor and McClennan (1985)
Earth
258
0.0203
0.0813
Hofmann (1988)
Earth
240
0.0203
0.0795
McDonough and Sun (1995)
Earth
235
0.0202
0.0764
Van Schmus (1995)
Earth_average
228.25
0.0197
0.0753
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