Quaternary Modelling

Quaternary Modelling

The AGS produces maps, cross sections, and three-dimensional (3D) models of the shallow Neogene-Quaternary sediments of Alberta, which form the sedimentary succession between the bedrock topography and the ground surface (Figure 1). These sediments include Paleogene to Neogene stratified sediments, particularly preglacial sand and gravel, lacustrine and eolian deposits, and glacial sediments deposited by the Laurentide and Cordilleran Ice Sheets. The 3D models provide the geological framework for shallow (<300 metres deep) groundwater resource modelling, and modelled stratigraphic units are integrated into the provincial Geological Framework.

Figure 1. Example of sediment thickness in the Sylvan Lake sub-basin study area in central Alberta, projected onto the bedrock topography along with the location of the Red Deer paleovalley (Sylvan Lake sub-basin study).

The Quaternary modelling team also creates stratigraphic, lithostratigraphic, and hydrostratigraphic cross sections of nonglacial and glacial sedimentary successions in Alberta. For example, cross sections (Figure 2a) in the Sylvan Lake sub-basin study contain multiple stratigraphic units, with complex stratigraphic relationships that infill the Red Deer paleovalley. Modelling the geometry of these sands and gravels (Figure 2b) provides insights into the distribution of coarse-grained units that potentially host significant aquifers. These 3D models can then be used to inform regional groundwater resource management.

Figure 2. a) Cross section from the Sylvan Lake sub-basin groundwater modelling project showing the major lithostratigraphic units across the Red Deer paleovalley and

b) the 3D framework model (Sylvan Lake sub-basin study).

In addition to providing the geological framework for groundwater studies, products derived from the models (i.e., the plan view maps showing the extent and thickness of units, as well as cross sections and 3D gridded frameworks) can provide a regional context for land-use applications and sand and gravel resource assessments, and advance our understanding of the depositional history of Alberta during the Neogene-Quaternary.