Philippines Pacific North

60 70 80 90 100 110 120 130 140 150 160

-10 0 10 20 30 40 50 60

10 mm/yr

Indian plate

Phil. Sea plate

Pacific plate

Australian plate Eurasian plate

Figure 2. GPS velocities with respect to Eurasia. Only sites with velocity uncertainty less than 1.5 mm/yr (95%

confidence) are used and shown here. Solid arrows show GPS site velocities withing Asia, open arrows show ve- locity of neighboring plates.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 25

Eurasia

Arabia

Australia

Philippines Pacific North

America

India

70 80 90 100 110 120 130

10 20 30 170 180 -170

40-10010203050

-1001020305040

65 55

71 90

59 96 79 1

15

25 30

38 35

101

45°

28°

65°

90°

Subduction

Null vel. in any direction Free vel. in E-W direction Null vel. in N-S direction

Tectonic Plate Velocities (mm/yr) (Sella et al., 2002)

India

35

Fault dip angle

}

Boundary conditions:

Figure 3. Finite element grid, boundary conditions, and faults used in the models.

70 80 90 100 110 120 130 140 150 mW/m

60

Heat-flow

70 80 90 100 110 120 130

10 20 30 170 180 -170

40 -1 0 0 10 20 30 50

-1 0 0 10 20 30 50 40

Figure 4. Map of surface heat flow used in the mod- els. Heat flow data comes from the worldwide database compiled byPollack et al.[1993] and fromLysak [1992]

for the Mongolia-Baikal area, resampled and interpolated on a 5^◦x5^◦grid for most of the study area, except in the Mongolia-Baikal area, where we used a 12’x12’ grid.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 27

0 100 200 300 400 500 600 0

10 20 30 40 50 60 70 80 90 100

Shear stress (MPa )

Depth(km)

Rheology 1 σs= 1.46x10 Pa¹²

0 100 200 300 400 500 600 0

10 20 30 40 50 60 70 80 90 100

Shear stress (MPa )

Rheology 2 σ_s = 3.41x10 Pa¹²

Figure 5. Examples of rheological profiles for a 45 km thick crust and a 0.059 W m²surface heat flow obtained using the thermal thermal parameters listed in Table 1, withµ = 0.85, and ˙ε = 3×10⁻¹⁶/s. Black lines shows frictional sliding, grey line is for non-Newtonian ther- mally activated dislocation creep.

70 80 90 100 110 120 130

-1001020305040

D

60 80 100 120 140 160 180 km

40

70 80 90 100 110 120 130

-1001020305040

C

70 80 90 100 110 120 130

-1001020305040

B

14 21 28 35 42 49 56 63 70 km

7

70 80 90 100 110 120 130

-1001020305040

A

Crustal thickness

Lithospheric thickness

Figure 6. Crustal and lithospheric thicknesses derived from the two sets of thermal parameters tested here (A

& C from the weaker rheology, B & D from the stronger rheology).

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 29

0.6 0.8

0.04 0.08 0.12 0.16

5.6 6

15MPa

0.6 0.8

0.04 0.08 0.12 0.16 5.4

6

Internal friction coefficient20MPa

0.6 0.8

0.04 0.08 0.12 0.16 5.4

25MPa 6

A 2MPa

0.6 0.8

0.04 0.08 0.12 0.16 5.2 5.4 5.6 5.8 0.6

0.8

0.04 0.08 0.12 0.16 4.4

4.8

5.2 0.6

0.8

0.04 0.08 0.12 0.16 4.4

4.8

5.2

4MPa

Maximum shear stress on oceanic subduction (To)

0.6 0.8

0.04 0.08 0.12 0.16 7 0.6

0.8

0.04 0.08 0.12 0.16 6 0.6

0.8

0.04 0.08 0.12 0.16 6

6MPa

0.6 0.8

0.04 0.08 0.12 0.16 8 9

15MPa 11 0.6 0.8

0.04 0.08 0.12 0.16 8

9 11

Internal friction coefficient20MPa

0.6 0.8

0.04 0.08 0.12 0.16 8

25MPa 10

B

Maximum shear stress on continental subduction (Tc)

0.6 0.8

0.04 0.08 0.12 0.16

5.4 6

7

Fault friction coefficient

0.6 0.8

0.04 0.08 0.12 0.16 5.4 6

7 0.6 0.8

0.04 0.08 0.12 0.16 5.4 6

7

0.6 0.8

0.04 0.08 0.12 0.16

5.6 6

0.6 0.8

0.04 0.08 0.12 0.16 5.4

6 0.6 0.8

0.04 0.08 0.12 0.16 5.4

6

4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0

R M S (mm/yr)

Figure 7. Result of the model parameter grid search for the weaker (A) and stronger (B) lithospheres tested here. Countour lines show the RM S of the fit of GPS (Figure 2) to model velocities.

Figure 8. Reference model. A (top) - Model (black ar- rows) and observed (white arrows) horizontal velocities.

B (bottom) - Residuals (observed minus model) veloci- ties. Note the difference in velocity scale between the two figures. Choice of model parameters is explained in text (section 4.2) and summarized in Table 3.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 31

Figure 9. Model 1: Horizontal surface velocities pre- dicted by a model involving only gravitational potential energy gradients. See Table 3 and text (section 5) for a full explanation of the model parameters.

Figure 10. Model 2: Horizontal surface velocities predicted by a model involving gravitational potential energy gradients, a 20 MPa maximum shear traction at continental subductions, and zero velocity along the continental-Eurasia plate boundaries. See Table 3 and text (section 5) for a full explanation of the model pa- rameters.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 33

Figure 11. Model 3: Horizontal surface velocities pre- dicted by a model involving gravitational potential en- ergy gradients, a 20 MPa maximum shear traction at con- tinental subductions, and REVEL velocities [Sella et al., 2002] along the continental-Eurasia plate boundaries. See Table 3 and text (section 5) for a full explanation of the model parameters.

Figure 12. Model 4: Horizontal surface velocities pre- dicted by a model involving gravitational potential en- ergy gradients, a 20 MPa maximum shear traction at continental subductions, a 4 MPa maximum shear trac- tion at the oceanic subduction, and the REVEL veloci- ties [Sella et al., 2002] along the continental-Eurasia plate boundaries. See Table 3 and text (section 5) for a full ex- planation of the model parameters.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 35

Figure 13. Model 5: Horizontal surface velocities pre- dicted by a model involving boundary and buoyancy forces as in the reference model except that the buoy- ancy forces result only from gravitational potential en- ergy gradients in the continents. See Table 3 and text (section 6.1) for a full explanation of the model parame- ters.

Figure 14. Model 6: Horizontal surface velocities pre- dicted by a model involving no gravitational potential energy gradients, and simulating free motion at oceanic subductions and the India-Eurasia relative plate veloci- ties at the India-Eurasia plate boundary. See text (sec- tion 6.2) for a full explanation of the model parameters.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 37

Figure 15. Color background shows the second invari- ant of the strain rate tensor from the best-fit model (see section 4.2 and Table 3 for full explanation of the model parameters, and Figure 8 for the representation of the best-fit horizontal velocity field). The 3 ppb/yr value is contoured for reference. Black crosses show principal strain rate directions. Convergent arrows indicate com- pression, divergent arrows indicate extension.

60˚ 80˚ 100˚ 120˚ 140˚ 160˚

0˚

20˚

40˚

60˚

21.0 22.0 23.0 24.0 25.0

60˚ 80˚ 100˚ 120˚ 140˚ 160˚

0˚

20˚

40˚

60˚

60˚ 80˚ 100˚ 120˚ 140˚ 160˚

0˚

20˚

40˚

60˚

Log10[effective viscosity] (Pa s) 23

23 23

22 22

Figure 16. Color background shows the vertically aver- aged effective viscosity (in Pa s) in the reference model.

The amplitude is presented on a logarithmic scale. The 10²²and 10²³Pa s values are contoured for reference with white dashed lines.

VERGNOLLE ET AL.: DYNAMICS OF CONTINENTAL DEFORMATION IN ASIA X - 39

Karakorum

Altyn Tagh (87-94E)

Xianshuihe Jiali

Haiyuan Kunlun

Tien Shan Baikal

Gobi-Altay

10 20 30

slip rate (mm/yr)

Quaternary rates Geodetic rates

Best-fit model slip rates Model slip rates, low friction Edge-driven model slip rates

Figure 17. Comparison between Quaternary, geodetic, and model slip rates for major active faults in Asia. Best- fit models (section 4.2) uses a fault friction coefficient of 0.06, low friction model (section 6.4) and edge-driven model (section 6.2) use a fault friction coefficient of 0.01.

References for Quaternary and geodetic rates are given in the text.