Nan Zhang
Dept. of Physics
University of Colorado at Boulder
E-mail: nan.zhang@colorado.edu
Heat flux results:
HeatFluxes and HeatFlux_bounds
HeatFlux_peaks
Geoid for case14_7 and case14_8
1. For case14_7, I get similar surface velocity to that from the velocity
boundary condition when I reduce the lithospheric viscosity from 1 to 0.15.
The sign of the geoid above subduction does not change much. Movies: case14_7 and case14_7(weak margin)
2. For case14_8, when I reduce the lithospheric viscosity from 1 to 0.21,
the surface velocity becomes similar to that from the velocity boundary condition.
But, the geoid at S. America is not high enogh. Movies: case14_8 and case14_8(weak margin)
SuperC_TC:
Figure4
Figure6
Figure7
SuperC_Pangea:
1. The change of the plate motions at oceanic plates does not change the
evolution of mantle thermal structures under Africa hemisphere, though the
change does add a moderate downwelling at the southwest of the continental
region (case7_thermal_structures).
2. The moderate downwelling does not appear in standard case (case1) because
the oceanic plate configuration in the standard case put a ridge at the southwest
of the continental region (case1_thermal_structures).
The moderate downwelling may come from the geometry of the continental plates
(case7_downwelling).
3. The spectrum at three stages (458Ma, 390Ma, and 330Ma) for both standard
case (case1) and case7:
case1: step3000 step4400 step6500 The time series of spectrum with
the strongest degree one structure in case1
case7: step3300 step4500 step6700 The time series of spectrum with the
strongest degree one structure in case7
4. A new case will start with 4 oceanic plates from Lithgow-Bertelloni's
120 Ma reconstruction.
Yield_Stress_Cases: case1 has 1000 depth-dependent prefactor for top 150 km.
All the cases are in nappo:CitcomS-3.0.1/DATA or cappo:CitcomS-3.0.1/DATA_Yield.
1.Yield_case1 is on nappo erd37-48. Yield sress is 5e5. The (3,2) initial
perturbation can not break the lithosphere to generate the downwellings. It
is in stagnant lid regime.
2.Yield_case1_s has smallest yield stress 5e4 and is on cappo nodes13-24.
The thermal structure and viscosity on lithosphere at step
8000 (nondimensional time 0.25e-3): temp8000 visc8000
22000 (nondimensional time 1.02e-3): temp22000 visc22000
The horizontal velocity has decreased from step 8000 to 22000 probably because
the downwellings become more diffusive and the strain rate at the downwellings
are small.
3.Yield_case1_m(cappo nodes13-24), Yield_case1_m2(cappo nodes01-12),
and Yield_case1_m3(cappo nodes01-12) are serial cases with yield stresses
through 1e5, 9e4, and 8e4. Yield_case1_m3
(step 8000) has shown the strongest linear subductions compared withYield_case1_m (step 8000) and Yield_case1_m2 (step 8000).
4. The evolution of Yield_case1_m3: The expending range of breaking
faults stongly depends on how strong the downwellings are. After the tetrahedral-shape
downwellings form from the (3,2) perturbation (temp1000 and visc1000), the breaking faults expand
to largest (temp8000 and visc8000 at nondimensional time 0.248e-3).
Then, the expending range of the breaking faults decreases due to the diffusion
of the strong downwellings (temp16000
and visc16000 nondimensional time
0.48e-3). From the global average heat fluxandrms velocity, I have to wait to nondimensional
time 1~2e-3 to see the future of the case (if I can get degree-1). The horizontal velocityis decreasing
from step 8000 to 16000.
5. Yield_case1_m_init2(cappo nodes13-24) starts from the 10000 step
of case3 of our 2007 paper with yield stress 1e5. It shows similar evolution
as Yield_case1_m3. I want to run to 2e-3. Its thermal structures and viscosity
on the lithosphere are:
temp8000 and visc8000(1 and 2) at nondimensional time 0.23e-3.
temp12000 and visc12000 at nondimensional time
0.31e-3.
The horizontal velocityis
decreasing from step 8000 to 12000. The global average heat flux and rms velocity.
6. The viscosity profiles from
case3, s, m3, init2. The black one is for case3; red one is for Yield_case1_s;
green one is for Yield_case1_m3; and blue one is for Yield_case1_m_init2.
The horizontal velocity from case3, s, m3,
init2. The black and red ones are for case3 at 10000 step and 42000
step; the green one is for Yield_case1_s at step 22000; the blue one is for Yield_case1_m3
at 16000 step; and the purple one is for Yield_case1_m_init2 at 12000 step.
For the results of Yield_case1_m3 and Yield_case1_m_init2, I can see some
similarity from the figures 3 and 7 of Paul Tackley's 2000 paper, though he
did not use low viscosity zone for upper mantle.
The main question is: what sort of variable can be the indicator to
see the trend to degree-1 convection, still horizontal velosity?