Page 259 - Global Tectonics

Koons and modified from Koons et al., 2003, with permission from the Geological Society of America). (a) Initial model where crust is dragged along its base at
convergent components are accommodated on two separate structures. (g–k) Results with velocity profiles and strain rate analysis for a model that includes
Figure 8.24 Mechanical model of oblique compression between two plates involving a two-layered crust above mantle lithosphere (images provided by P.
velocities of 40 mm a −1 parallel to the y-axis (V y ) and 10 mm a −1 parallel to the x-axis (V x ). Crustal rheology is horizontal and not yet perturbed by advection.
rates. (d) Vertical profile parallel to the xz plane showing distribution of vertical motion and (e) plot of convergent strain rates. (f) In this model lateral and
(b) Vertical profile constructed parallel to x-axis showing the component of motion parallel to the y-axis (velocities in mm a −1 ) and (c) plot of lateral strain
thermal weakening associated with exhumation and concentrated erosion. At this stage both lateral and convergent components of motion are
thermal anomaly developed
Vy
Shortening component
Evolved stage:
Lateral component
(km)
Distance
Single oblique structure

(g)
(l)
Vy
10 mm a -1 N 10 mm a -1 Australia Pacific elevation km km Plate Elastic 500 500 40 mm a -1 Vx Constant 10 350°C 8 6 2 4 30 Mantle Pacific km 400 50 km 400 120 80 200 160 40 0 Lateral strain rates Lateral strain rates (i) (h) 10 + ) Vy (mma -1 30 V 30 20 y + 10 50 40 Depth (km) 160 120 80 40 40 0 200 0 (km) Distance Convergent strain rates (k) (j) Convergent strain rates 6 10 4 2 30 V z -2 50 Depth (km) 40 120 80 40 40 0 200 160 0 CONTINENTAL TRANSFOR
40 mm a -1 200 (c) + 0 200 (e) 200 0 Initial stage: no thermal anomaly
)
Pacific Plate 350°C Mantle 120 160 V Vy (mma -1 y 120 160 (km) V z 120 160 (km) accommodated along a single dipping structure in the upper crust (l) and may separate in the lower crust.
elevation Main divide Vx 8 Pacific 80 80 Distance 80 Distance
Australia Constant 6 40 30 40 -1 -2 40

Elastic 4 2 20 3 2 1
N 10
(a) 0 (b) 0 (d) 0
x 30 50
y 10 30 50 10 (f)

Depth (km)
Depth (km)

z