Page 309 - Global Tectonics

OROGENIC BELTS 293

km
0 5 10
km
0 5 10
S km km
50 10 10
SE 0 5 50 0 5
C - Mz u. C - O - -- pC-C 010 km km
Subandean Zone Villamontes 50 T S - D Sta. Bárbara System 10 0

km
NW
10
E
0 Sa. de Zapla

Interandean Zone Shortening: 150 km (approx. 42%) Shortening: 30 km (approx. 20%) 0 10 20 (a) Sketch map showing the transitions from thick to thin lithosphere under the Central Andes as determined from seismic wave attenuation

Eastern Cordillera Tanjia Eastern Cordillera W 0 10 20 T κ u. C-D - km - pC-m. C data. Zone of thick lithosphere correlates with areas of strongest shortening gradient. Santa Bárbara system (SBS) is characterized by thick-skinned deformation. Thin-skinned thrust belt (b) and restored section (c) of the sub-Andean ranges, Bolivia using data from Baby et al. (1992), Dunn et al. (1995), and Kley (1996). Thick-skinned thrust belt (d) and restored section (e) of the Santa Bárbara system (all images

W (d) km (e) -
0 10 20
(b) km (c)
15 S 20 S 25 S 30 S
60 W Strong shortening gradient Fig. 10.5d

Strong shortening gradient Foreland Fig. 10.5b

65 W Subandean Ranges

W Elsevier). Location of profiles (b) and (d) also shown on Fig. 10.4.
70
NAZCA PLATE

W Low Q/ thin lithosphere
75
Figure 10.5
(a)