Relationships between pore pressure, stresses, and present-day geodynamics in the Scotian Shelf, offshore eastern Canada
- Univ. of Waterloo, Ontario (Canada)
- Geological Survey of Canada, Calgary, Alberta (Canada)
A geomechanical study of the Mesozoic and Tertiary sediments beneath the Scotian Shelf shows that two major weak layers exist at depth: the over-pressured unit at 4000 m and the basal Argo salt, which is ductile and diapiric. A consistent relationships is observed between the overpressures and the stress state in the basin. First, the smaller horizontal principal stress increases dramatically just above the onset of overpressuring, and secondly, borehole breakouts, indicators of stress anisotropy-decrease in abundance within the overpressure zone. Neither tectonic shear nor rapid burial can explain these observations; however, overpressuring by fluid generation will result in horizontal stress increase and eventually lead to an isotropic stress state. Compelling evidence is found for hydrocarbon generation being a key cause of overpressuring in the Scotian Shelf.
- OSTI ID:
- 44950
- Journal Information:
- AAPG Bulletin, Vol. 78, Issue 12; Other Information: PBD: Dec 1994
- Country of Publication:
- United States
- Language:
- English
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