Page 181 - Global Tectonics

CONTINENTAL RIFTS AND RIFTED MARGINS 167

(a)

SHEEP RANGE BLOCK BLOCK mp ts ts 37 N
SHEEP RANGE
mp

SIERRA NEVADA SIERRA NEVADA kr kr SPRING MOUNTAINS BLOCK COLORADO PLATEAU COLORADO PLATEAU 36 N

eb
SPRING MOUNTAINS BLOCK
MOJAVE DESERT eb
MOJAVE DESERT
BLOCK
BLOCK
118 W 117 W 116 W 115 W 114 W
Alluvial cover ( 2.5 Ma) Rocks 2.5 Ma Relatively minor Neogene tectonism
(b)
38 N
0 25 50
km

37 N

36 N

35 N
118 W 117 W 116 W 115 W 114 W
15 km 15–10 km 10–5 km 5–2.5 km 2.5 km
Figure 7.13 Maps showing (a) major Cenozoic faults (heavy black lines) in the central Basin and Range Province and
(b) the distribution of upper crustal thinning estimated by reconstructing Cenozoic extension using pre-extensional

markers (images provided by B. Wernicke and modified from Snow & Wernicke, 2000. Copyright 2000 by American
Journal of Science. Reproduced with permission of American Journal of Science in the format Textbook via Copyright
Clearance Center). Symbols in (a) indicate strike-slip faults (arrows), high-angle normal faults (ball and bar symbols),
low-angle normal faults (tick marks), and thrust faults (teeth). Large-magnitude detachment faults in metamorphic
core complexes include the Eldorado-Black Mountains (eb), the Mormon Peak (mp), Tule Springs (ts), and the Kingston
Range (kr) detachments. Contours in (b) represent the remaining thickness of a 15-km-thick pre-extensional Cenozoic
upper crust, such that the lightly shaded areas represent the areas of greatest thinning. Black dots are points used in
the reconstruction.