Print this pageMesozoic Subsidence Rates and Lithospheric Loading in Western Canada Basin
Valerie E. Chamberlain, W. Stuart McKerrow, Richard S. Lambert
The Mesozoic stratigraphy of the Foothills area of the Western Canada basin
has been used to estimate sedimentation rates, and, hence, relative crustal
subsidence rates, in this region throughout the Mesozoic. Average rates of
subsidence range from 0 
m
/Ma to 120 m/Ma, with prominent maximums occurring
three times during the Mesozoic--first during the Tithonian, when rates rose to
100 m/Ma, second, during the Albian to early Santonian, when rates rose to 120
m/Ma in the north and to 70 m/Ma in the south, with subsidence occurring earlier
in the north than in the south. The third period of subsidence occurred during
the Campanian and Maastrichtian with rates rising to 120 m/Ma in the southern
part of the basin. Tectonic loading of the lithosphere is the probable cause of
th se peak crustal subsidence rates, the three separate episodes being due to
the arrival of accreted terranes, first in northeast Oregon and central west
Idaho during the Late Jurassic, secondly in the central Yukon during the Early
Cretaceous, and thirdly in southeast British Columbia during the Late
Cretaceous. During non-peak periods, average rates of subsidence ranged from 3.5
m/Ma to 35 m/Ma in the Triassic, from 0 m/Ma to 20 m/Ma in the Jurassic, and
from 0 m/Ma to 30 m
/Ma in the Cretaceous.
AAPG Search and Discovery Article #91040©1987 AAPG Rocky Mountain Section Meeting, Boise, Idaho, September 13-16, 1987.