Twentieth Percentile Modelled Base of the Paskapoo Formation, Alberta (Gridded data, ASCII format)

The base of the Paskapoo Formation is unconformable with the underlying Scollard Formation. Alberta Geological Survey differentiates the Paskapoo Formation from the underlying Scollard Formation by the first thick sandstone above the uppermost coal seam of the Ardley coal zone. We defined 'thick sandstone' to be 5 m or more thick. This dataset contains the gridded results of the structural surface of the base of the Paskapoo Formation modelled from stratigraphic picks of the >5 m sand above the Scollard Formation coal from oil and gas industry gamma-ray logs. We modelled only the undeformed part of the Paskapoo Formation, which lies east of the Rocky Mountains deformation belt. Because of uncertainty in defining the Paskapoo-Scollard contact, we selected the P20 (20th percentile or low estimate) modelled surface of those data, which is about 5 m deeper than the P50 or median estimated surface. Subsequent boundaries of slices were constructed parallel to this surface, recognizing that, locally, the base of the Paskapoo Formation has an undulating to incised erosional contact with the underlying Scollard Formation. The model illustrates an elongated, concave surface with a central region plunging westwards towards the Alberta syncline and elevated limbs to the northwest and southeast.