Tunnel-channel complexes in the Zephyr area, Ontario: potential high-yield aquifers

In south-central Ontario, tunnel channels are primary targets for groundwater exploration due to their potential to contain confined, water-bearing, coarse-grained sediment fills. Despite extensive hydrogeologic and geologic exploration within these features, a comprehensive depositional model that illustrates the spatial distribution of coarse- and fine- grained sediment in tunnel-channel complexes is absent. Work in the Zephr area, north of ORM, presents new subsurface data to improve understanding of this geologic setting and to add to geologic models of these channel systems. Findings result from combined geology, sedimentology, geophysics (seismic profiling) and sediment drilling (mud rotary and continuous core) to better our understanding the shallow channel setting north of ORM, including: 1) spatial distribution of coarse- and fine-grained sediments in tunnel-channels; 2) the architecture of tunnel-channel sequences in confluence zones. Preferred aquifer targets aquifer units in the Zephyr area are identified in areas of channel confluence and channel bends. Channel aquifers are confined by 3.9 to 28.5 m thick deposits of rhythmically bedded silt and clay.