Geoscience Reference
In-Depth Information
Table 10.2
The area of continental basement
Area (10
6
km
2
)
Age (Ma)
Percentage of total area
0-450
38.2
29.5
450-900
41.1
31.8
900-1350
14.6
11.3
1350-1800
8.7
6.7
1800-2250
19.4
15.0
2250-2700
6.2
4.8
2700-3150
1.1
0.9
Total
129.3
Source
: Hurley and Rand (1969).
0-250 Ma
250-800 Ma
800-1700 Ma
>1700 Ma
Figure 10.5.
The age of the continents. (After Sclater
et al
.(1981).)
cratons are the Grenville and Appalachian rocks, which accreted much later
as a result of continental collision. In the west, the Cordilleran rocks (western
mountains) comprise a series of
accreted terranes
,which have been added, or
accreted, to the continent during the last 200 Ma. These terranes, which comprise
material of continental, oceanic and island-arc origin, have been added to the
