ABSTRACT

Compaction of sedimentary units depends on at least three variables: lithology, initial thickness of the sediments, and maximum effective stress applied to the beds, where the last is a function of the rate of loading. Where a unit changes laterally in thickness and/or compactability its response to overburden loading is distinctly nonuniform. This commonly produces structural deformation (drape) in the overlying beds. It has been shown that measurements of the amount of drape at various levels can be used to recover the compaction history of the sequence, usually shown as the compaction curve. The technique has been developed by Labute and Gretener in 1969 and applied to the Upper Devonian Leduc reefs and Ireton shales of central Alberta. In this paper we show that the 'compaction curve' can also be used to detect such features as reef collapse, rebound, and undercompaction. In certain cases quantitative estimates of the amount of collapse or erosion may be made.