Page 354 - Global Tectonics

OROGENIC BELTS 337

Kv
Sp R Principal terranes
En NS Alaska and Western Canada
R
NS North Slope
G NF I Kv Kagvik
Cl PM ALASKA En Endicott
YT YUKO N R Ruby
P PM Sp Seaward Peninsula
Innoko
I
Cg NF Nixon Fork
TA PM Pingston and McKinley
T YT Yukon – Tanana
YT Cl Chuiitna
P Peninsular
W Wrangellia
W
E Cg Chugach and Prince William
Ax Ch TA Tracy Arm
TA T Taku
Ax Alexander
St G Goodnews
Ch Cache Creek
Ch St Stikine
BR Bridge River
E
BR E Eastern assemblages
Washington, Oregon and California
SJ
O Ca Northern Cascades
CANADA
Ca SJ San Juan
S USA O Olympic
Fh W S Siletzia
Trp
BL BL Blue Mountains
Trp Western Triassic and Paleozoic of Klamath Mountains
KL KL Klamath Mountains
F Si S Fh Foothills Belt
San Francisco
GL F Franciscan and Great Valley
Fh C RM C Calaveras
Sa Si Northern Sierra
SG San Gabriel
Mo Mohave
Mo Sa Salinia
Or Orocopia
SG
Or Nevada
B
USA S Sonomia
0 600
MÉXICO RM Roberts Mountains
km GL Golconda
V
Mexico
B Baja
V Vizcaino
Figure 10.32 Generalized map of suspect terranes in western North America. Stippled ornament, North American
cratonic basement; barbed line, eastern limit of Cordilleran Mesozoic–Cenozoic deformation; solid ornament,
Wrangellia; diagonal ornament, Cache Creek terrane (redrawn from Coney et al., 1980, with permission from Nature
288, 329–33. Copyright © 1980 Macmillan Publishers Ltd).
rifting events between 1.74 Ga and the Middle Devonian terrane, called the Intermontane Superterrane, began
created thick passive margin sequences that were depos- to accrete onto the continental margin. The collision
ited on top of Proterozoic crust of the North American shortened the passive margin sequences and translated
craton (Thorkelson et al., 2001). These sequences them eastward, resulting in a major foreland fold and
occupy the central part of SNORCLE Line 2B/21 (Fig. thrust belt that now forms most of the eastern Cordil-
10.33a,b). During the Middle Jurassic, a composite lera. West of the foreland, the Omineca belt consists of