ABSTRACT

The basic approach used to interpret sedimentary sequences in the context of sequence stratigraphy is the recognition of changes in coastal onlap patterns. On passive continental margins, this approach is the most useful since the basin margin which sediments onlap (i.e. the landward margin) is frequently preserved and available for study. In a foreland basin, coastal onlap patterns are often not preserved.

The portion of a foreland basin most easily studied is the distal end, which often comprises marine lithofacies. The analytical approach most easily applied in clastic wedges is the determination of the position of relative basinal downlap based on the distal progradational limits of sandstone into the basin (i.e. seaward) and the parasequence stacking patterns. Regional unconformities and systems tract boundaries may be recognized by the truncation of log markers, by changes in parasequence stacking patterns, and by paleontological data. Using an example from the Upper Cretaceous Dunvegan Formation, this data is used to construct Wheeler diagrams from which the basin history is inferred.

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