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The AAPG/Datapages Combined Publications Database
CSPG Bulletin
Abstract
C.S.P.G. 1990 Convention, "Basin Perspectives"
Mass Accumulation Rates of Foreland Basin Sediments, Peace River Arch Area [Abstract]
ABSTRACT
Volumetric sedimentation rates have been used previously to quantify the dynamics of sedimentary processes. Their calculation is usually done on one- or two-dimensional local scales, and requires decompaction of strata, which introduces approximations in the results. The use of mass accumulation rates avoids the need for decompaction and provides the same information (except for lithospheric loading) on a three-dimensional regional scale. Moreover, by avoiding the need for decompaction, the uncertainty inherent in sedimentation rates is reduced. The regional distribution of mass accumulation rates for a specific unit pinpoints the source areas and gives a general indication of the depositional environment. The magnitude
of the mass accumulation rates can be related to the tectonic conditions in the adjacent deformed belt.
Mass accumulation rates in the Peace River Arch area were calculated for foreland basin units based on porosity and grain density data from core analyses at approximately 22,000 wells. They show that tectonism can result in either the deposition of a sand or shale, depending on the rock type being exposed to erosion. During the Albian, Cordilleran deformation lead to the rapid accumulation of the Bluesky and Upper Spirit River sands. Deformation from late Cenomanian to late Coniacian time resulted in the rapid accumulation of the Puskwaskau and Muskiki shales. The results show that deposition of a shale does not necessarily imply slow accumulation during a period of quiescence. Conversely, the deposition of a sand does not always imply rapid sedimentation and associated tectonism. The source rock controls the sediment lithology, and the state of tectonism controls the accumulation rate.
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ACKNOWLEDGMENTS AND ASSOCIATED FOOTNOTES
1 Alberta Geological Survey, Edmonton T6H 5X2
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