Chandler Noyes, Jennifer C McIntosh , Nicholas Dutka, Rebecca Tyne, Matthew Lindsay, Grant Ferguson

Continental glaciations during the Pleistocene Epoch created complex systems of aquifers and aquitards across many northern regions of the Earth. Past measurements of δD and δ18O measurements show that tills have retained subglacial meltwater but the behaviour of intertill and buried valley aquifers in these regions is less clear. Here, we characterize groundwater ages in these aquifers in Saskatchewan, Canada. Groundwater ages in intertill aquifers are predominantly younger than ~10.3 ka, indicating that they primarily contain water recharged after the retreat of the Laurentide Ice Sheet. Buried valley aquifers contained waters with ages >38 ka in some locations, indicating that recharge occurred prior to the Last Glacial Maximum (LGM). These ages suggest the presence of flow systems with recharge taking place both before and after the LGM, deemphasizing the importance of that event in emplacing groundwater resources in intertill and buried valley aquifers.