NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region

Tags: physical sciences, geology, ground ice, mineral deposit, acid rock drainage

Objective(s): To examine the geological characteristics of Cretaceous (~78-88 Ma) metal-rich Smoking Hills Formation mudstones (black shale) and understand the mechanisms by which these metal-rich deposits formed, their extents and stratigraphic variability, and the release of dissolved metals into surface waters through natural acid rock drainage and land-sliding. To understand the timing and significance of several sediment deposits exposed in natural sections that are potentially derived from both the last glaciation and from previous glaciations.

Project Description: This licence has been issued for the scientific research application No.5547. This research project proposes to examine the geological characteristics of Cretaceous (~78-88 Ma) metal-rich Smoking Hills Formation mudstones (black shale) and understand the mechanisms by which these metal-rich deposits formed, their extents and stratigraphic variability, and the release of dissolved metals into surface waters through natural acid rock drainage and land-sliding. Studies of acidified waters and rare mineral types found in areas of spontaneously combusting mudstone will help understand the environmental dynamics of natural geological processes operating in the Smoking Hills. Research is also proposed to understand the timing and significance of several sediment deposits exposed in natural sections that are potentially derived from both the last glaciation and from previous glaciations. A unique site of exposed buried glacial ice that was discovered in 2018, may preserve ice dating prior to the last glaciation would also be examined. Aspects of its age, chemistry and sediment content would be assessed to better understand the timing of past glaciations, and the degree to which the most recent glaciation altered the landscape and regional permafrost record. Studies of bedrock geology require us to visit naturally occurring exposures (small cliffs, river cut sections, and headwalls of landslides), to measure and record aspects of the stratigraphy (sediment types, thickness and dip (inclination) of different beds). Based on results from the 2018 field work, proposed focus is on sites of recent land-sliding, sampling along the edge of the landslide headwall, to recover the least weathered (oxidized) material. Because the Smoking Hills Formation bedrock is so poorly consolidated, hand shovels, trowels and rock hammers can be used to clear off small areas and remove small (1 kg) samples of rock for laboratory analysis (in the case of a few age dating samples, up to 5 kg may be required). Sample analyses will vary depending on the types of rock and the questions being asked, but may include palynology (environmental reconstruction), macro-fossils (e.g., foraminifera), geochemistry, and geochronology (dating of materials). Collecting these small hand-sized samples in recent landslide-exposed sections of Smoking Hills Formation bedrock throughout the study area will help in the regional characterization and correlation of the bedrock units. It is estimated that up to 100 samples may be collected throughout the field area. Surface water samples (ponds, streams and rivers) would be collected throughout the extents of exposed Smoking Hills Formation bedrock. Small samples of water (<1 litre) would be collected from the edges of small streams and ponds and filtered on site, using hand pump filter systems. Non-motorized inflatable kayaks would be used to sample waters at various depths and locations in the Horton and Anderson rivers, and in larger ponds. Water samples would be preserved in the field and shipped south for analyses. Natural exposures of glacial sediments will be assessed in the field, and samples for geochemistry, sedimentology, paleobotany, and age dating (OSL and cosmogenic nuclide) will be collected for analysis. Two sites will be focused on, but others may be included as new areas that were not investigated in 2018 are explored. The first site appears to preserve glacially rafted oxbow lake/floodplain deposits, containing several layers of trees rooted in place, and marl and leaf litter deposits. The second preserves a stratigraphy of 3 remnant ice wedge pseudomorphs in a 10 m section of glaciolacustrine sediments. Natural exposures of buried glacial and other ice deposits (e.g. ice wedges) will be accessed using climbing ropes and specialized climbing equipment. Samples will be collected using a gas-powered drill with a 2-inch diameter concrete drill bit, a chainsaw (for areas of “clean” sediment-free ice wedges), and by chipping small samples (<1 litre) using an ice axe. Samples will be thawed and filtered in the field, and then shipped south for analyses. Attempts to date ice wedges using the CO2 trapped in air bubbles will require collection of larger intact ice samples. These 30 x 30 x 30 cm chunks of ice will be cut from ice wedges using a chainsaw, and then preserved frozen in the field using a portable electric-powered freezer. Larger samples are required to ensure that any material lost to melt during sampling, storage and transport will ensure sufficient material remains for analysis. Using the gas-powered drill, we are also hoping to collect 5 samples of frozen soil above and below the active layer, to assess the relative concentrations of dissolved metals and acidity in areas draining off Smoking Hills Formation bedrock. These samples will be collected to assess the potential of increased solute release, brought on by climate change-induced thickening of seasonal active layer depths. These soil samples will be kept frozen and shipped south for analysis. With respect to the proposed project at hand, the GEM GeoNorth Engagement team initiated meetings with the Inuvialuit Regional Corporation in 2022, and then provided letters broadly outlining the proposed scientific research in the affected communities of Paulatuk and Tuktoyaktuk in early February 2023. Follow-up is planned, including community visits and engagement meetings for late February 2023, where proposed activities will be presented to seek the guidance and participation (e.g. hiring of wildlife monitors) of community members. If the project moves forward, contact and sharing information and results of our work will be maintained with the communities and the IRC throughout the life of the project and beyond as publications continue to arise from this research. Further in-person community engagement and information-sharing meetings will be scheduled in 2024 to discuss analytical results to-date, and the timeline for completion of other analyses and products. The fieldwork for this study will be conducted from: July 11 - July 27, 2023