This dataset is part of the 3D hydrostratigraphic model of the Calgary-Lethbridge Corridor (CLC), southwestern Alberta. It represents the structure top of the Horseshoe Canyon / St. Mary River hydrostratigraphic unit (HSU) in the CLC. Bedrock units included in the CLC model are derived from the Geological Framework of Alberta, a regional geological model of the province. The top of the Horseshoe Canyon / St. Mary River HSU, provided by the Geological Framework of Alberta, was clipped to the CLC model domain for integration into a multi-layer hydrostratigraphic model.
Alberta Geological Survey (AGS) Report 91 includes a full description of the process used to produce this structure grid.
The methodology to create this grid dataset is fully documented in AGS Report 91.
Modelling software used to create grid: Petrel and ArcMap (grid interpolation) and RockWorks16 (deterministic alterations)
The picks detailed below were created and compiled by other authors and reported in this metadata record for user convenience.
Number of data points used: 9162
This includes all Horseshoe Canyon / St. Mary River HSU subsurface stratigraphic picks needed to reproduce the lateral extent of the Horseshoe Canyon / St. Mary River HSU in Alberta, including points that extend outside the CLC model domain.
Data type: Stratigraphic picks from published and unpublished AGS sources and the Alberta Energy Regulator corporate database.
Grid Interpolation Information:
The Geostatistical Analyst ArcMap extension was used to interpolate the elevation value for the top of the Horseshoe Canyon / St. Mary River HSU in Alberta. The following Method Report and Prediction Errors are reproduced in this metadata record for convenience to provide information about the parameters used to create the source grid, as well as the errors associated with the gridding process.
Method Report:
Method: Kriging
Type: Ordinary
Output type: Prediction
Variogram
Number of lags: 18
Lag size: 1100
Nugget: 0
Measurement error percentage: 100
Model type: Sperical
Range: 12000
Anisotropy: yes
Minor range: 9000
Direction: 283
Partial sill: 249
Prediction Errors
Total points: 9162
Mean: 0.0019
Root mean square error: 5.30
Mean standardized: -0.0014
Root mean square error, standardized: 1.94
Average standard error: 5.69
Deterministic Grid Alteration Information:
The grid of the top of the Horseshoe Canyon / St. Mary River HSU in Alberta (500 m cell-size) was exported from Petrel as geographic coordinates (X, Y) as well as elevation data (Z) sampled at each evenly-spaced grid node. The data was then imported into ArcMap and clipped to the CLC model domain. The X,Y,Z data were re-interpolated using closest-point in ArcMap at a 400 m cell-size node spacing, where grid nodes are set equal to the value of the nearest point.
The grid of the top of the Horseshoe Canyon / St. Mary River HSU in the CLC was exported to ESRI ascii format and imported into RockWorks16 for integration into the full hydrostratigraphic model.
Modelling constraints applied: The grid of the top of the Horseshoe Canyon / St. Mary River HSU was constrained to the CLC bedrock topography where the two grids intersected.