Influence of Precambrian rift trends on pre-Devonian deposition in southern Northwest Territories, Canada
A study incorporating all available outcrop, well, and geophysical data shows that pre-Devonian deposition in the southern part of the Northwest Territories of Canada was strongly influenced by a weakened basement framework of Precambrian horsts and grabens which developed in response to continental breakup and sea-floor spreading in the proto-Pacific. Major horsts continuously rose to form arches that shed clastics into the downdropping basins. As the highs were worn down, the deposits changed from dominantly clastic to largely carbonate and the highs were ultimately transgressed. Within the area the pre-Hadrynian basement consists of granite on the east, metamorphics and minor sediments throughout the central part, and unaltered sediments on the west. The three trends are believed to define a westerly transition from the old craton through an ancient rift zone to the proto-Pacific. To define the history, the pre-Devonian section was broken into major time-rock sequences which represent separate transgressive-regressive cycles of deposition terminated either by local or regional uplift and erosion or by renewed transgression. Within each sequence most lateral changes from thinner intertidal deposits to thicker deeper water ones were seen to occur in narrow transition zones, indicating that the cycles were dominated by differential vertical subsidence along major hinge lines. This Precambrian framework runs the length of western North America and controlled much of the early Paleozoic sedimentation along it. It also greatly influenced later Laramide thin-skin thrusting wherein the horst-cored arches acted as buttresses to the eastward-moving blocks.
- Research Organization:
- Texaco Canada Resources Ltd., Calgary, Alberta
- OSTI ID:
- 6221200
- Report Number(s):
- CONF-870606-
- Journal Information:
- AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States), Vol. 71:5; Conference: American Association of Petroleum Geologists annual meeting, Los Angeles, CA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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