Page 337 - Global Tectonics

320 CHAPTER 10

(a) (d) (g) 70 E 80 E100 E120 E 140 E 150 E 60 N 50 N 40 N

Strike-slip fault Motions with respect to Siberia
Normal fault Direction of extension
Thrust fault Oceanic crust in SE Asia
F 1 Subuduction zone
60 N
F SIBERIA
20 mm Baikal 150 E
30 N
JAPAN
(b) (e) 50 N
MONGOLIA
F 2 Shansi 140 E
40 N Altyn Tagh Fault 20 N
F 1 1 CHINA
Herat
Fault Fault
F F TIBET Yunnan 2
Karakorum
1 Kangting Fault
30 N Chaman Fault Himalayan frontal thrust
China 10 N
Red River Fault
(c) (f) Sea 130 E
F 2 20 N INDIA INDO-CHINA
2
2 1 0
F F F 1
1 10 N BORNEO
1 Burman Arc 10 S
1 2 0 120 E
80 E 100 E
Figure 10.22 (a–f) Indentation experiments on Plasticine and (g) schematic map illustrating extrusion tectonics in
eastern Asia (redrawn from Tapponnier et al., 1982, with permission from the Geological Society of America). F, major
fault. Numbers associated with arrows in (g) are extrusion phases: 1 ∼ 50–20 Ma; 2 ∼ 20–0 Ma.

case generates an asymmetric pattern where extensional regimes in Shansi, Mongolia, and
faults that allow displacement towards the Baikal. The Altyn Tagh Fault may correlate
free edge predominate, such as F 1 . The block with the major dislocation F 2 , and the Red
translated sideways rotates about 25° River Fault with F 1 . The comparison also
clockwise and is followed by the extrusion of suggests that indentation causes the
a second block along another sinistral fault, curvature of fault systems located east of
F 2, which allows a continued rotation of the Tibet. Finally, lateral extrusion between and
first block by up to about 40°. Pull-apart to the southeast of the Altyn Tagh and Red

basins (Section 8.2) develop along the sinistral River faults results in extension that
faults because of their irregular geometry. As resembles patterns observed in the South
these movements progress, a gap grows China Sea and the Gulf of Thailand (Fig.
between the indenter and extruded plasticine. 10.22g).
Tapponnier et al. (1982) suggested that these Since its development in the late 1970s and
results explain the dominance of sinistral early 1980s, the indentation model of
offsets in China (Fig. 10.22g). The pull-apart continental collision has evolved considerably.
structures may be analogous to the Although the model of Tapponnier et al.