| Title | Sandstone composition and diagenesis of the Paskapoo Formation and their significance for shallow groundwater aquifer in the Fox Creek area, west-central Alberta |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Lavoie, D ;
Tremblay, V; Rivard, C |
| Source | Geological Survey of Canada, Open File 8982, 2023, 92 pages, https://doi.org/10.4095/331923  Open Access |
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| Year | 2023 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | digital; on-line |
| File format | pdf |
| Province | Alberta |
| NTS | 83K |
| Area | Fox Creek |
| Lat/Long WENS | -118.0000 -116.0000 55.0000 54.0000 |
| Subjects | hydrogeology; stratigraphy; sandstones; diagenesis; groundwater; aquifers; hydrostratigraphic units; petrography; calcite; isotopes; oxygen isotopes; stable isotope studies; Paskapoo Formation; Haynes
Member; Lacombe Member; Dalehurst Member |
| Illustrations | location maps; stratigraphic columns; tables; lithologic logs; diagrams; plots |
| Program | Groundwater Geoscience Fox Creek Regional Aquifer System |
| Released | 2023 06 06 |
| Abstract | The shallow aquifer in the Fox Creek area is hosted by the Paleocene Paskapoo Formation. The formation consists of fluvial deposits with channel-filled high-energy sandstone cutting through
fine-grained, low energy overbank sediments. Three internal members are recognized, these members define three hydrostratigraphic units (two aquifers versus one aquitard). In fall 2022, three boreholes were drilled and cored. The succession is
slightly dominated by sandstone with subordinate fine-grained sediments and thin coal intervals. The calcareous to non-calcareous sandstone is either tight and well compacted or porous, friable to unconsolidated. The litharenite is composed of
quartz, various types of rock fragments, chert, and feldspars. Detrital carbonates can be abundant. The post-sedimentation history of the sandstone recorded cementation and dissolution events from near surface, through shallow burial and late
tectonic exhumation. The events include early clay coatings on grains, dissolution of metastable minerals, cementation from calcite, kaolinite and minor chlorite and late near surface fault-controlled freshwater circulation and dissolution. The late
event resulted in friable to unconsolidated sandstone intervals. |
| Summary | (Plain Language Summary, not published)
The fluvial deposits of the Paleocene Paskapoo Formation form the shallow aquifer in the Fox Creek area. The cores of three boreholes drilled in 2022
contain, at various depths, intervals of unconsolidated sands present between well compacted sandstones. These enigmatic intervals were rarely described previously and the cause for these was never addressed. Understanding the reason for these is
important as they constitute preferential intervals for aquifer high transmissivity. The petrography of 20 sandstone samples has shown that they are dominated by quartz and rock fragments, the coarse-grained sandstone commonly displays high porosity.
Particles are locally surrounded by thin clay rims and small volume of cements were precipitated in the pore space before the exhumation of the formation in Eocene. Evidence of dissolution of feldspars, carbonate and volcanic rock fragments are
visible, all of which increased the total porosity of the sandstone. Late freshwater infiltration along faults and fractures was responsible for a final major dissolution event in some highly porous beds leading to the creation of the unconsolidated
sandstone intervals. |
| GEOSCAN ID | 331923 |
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