Examples from other Foreland Areas
S.E. Hoover Field (Fig. Ill) on the north flank of the Arbuckle Anticline has well control that displays the fact that bedding plane slippage changes into reverse faulting upward in the direction of tectonic transport. The section has been arbitrarily flattened on the Basal Oil Creek sand to emphasize the development of closure above that level. The middle log is from a crestal well, and we see the change into reverse faulting at the point where it becomes a "cross-crestal" feature. A true-scale structural sketch of S.E. Hoover section is illustrated in Figure 112. Electric logs from the Springer shale of the Anadarko Basin show progressive repetition of the Springer shale up the flank of the basin (Fig.113). The recognition of the rule that thrusts cut up section in the direction of tectonic transport allows us to arrange these wells in a projected cross section that indicates that the thrust repetition of the logs on the right passes into bedding plane slippage in the well to the left. A cross section using all available well control shows that this development of the shallow structure at Carter-Knox is of the "cross-crestal" style and the result of movement in the Springer shale out-of-the-syncline(Fig. 114). Note that the fold closure and fault offset is passed downward to the left into bedding plane slip. If the well on the far left were deepened through this zone, no expression of the detachment would be recognized. Figure 115, which shows the Joiner City field in southern
Figures & Tables
This publication begins with the basics of definition and description of a foreland, and in particular North American foreland areas. It then goes into detail on Rocky Mountain foreland areas, covering general information, age of basement complexes, basement rock types, angles of basement faulting, contrast of structural concepts, predominant structural styles, and drape versus dynamic folding of sediments.