THE SMOKING HILLS FORMATION OF ARCTIC CANADA

The Smoking Hills Formation of Arctic Canada represents a Cretaceous organic-rich and metalliferous black shale named after auto-combusting exposures in Ingniryuat, Northwest Territories, Canada. This area was also named The Smoking Hills by the Franklin Expedition after the ever-present clouds of sulphuric acid smoke produced. New age determinations suggest correlation with similar burning Cretaceous mudstones in Yukon, northern Alberta, as well as western Greenland (as recorded in the Viking Sagas). These burning shales reflect deposition during OAE 2 and 3 events across the Arctic region. Metals in the Smoking Hills Formation are enriched on average >1000x average shale values and have been identified as potential economic REE deposits in some regions. The metal concentrations strongly correlate with heulandite content, an alteration product of volcanic glass, suggesting enrichment is related to volcanic loading, as supported by abundant bentonite beds in the Smoking Hills Formation. This is consistent with the eruption history of the High Arctic Large Igneous Province to the north, and Cretaceous arc related volcanics to the west. REE patterns are more consistent with an arc volcanic source. Volcanic fertilisation (nutrient loading) likely drove bioblooms accounting for the high organic content of these shales which supported drawdown and sequestration of metals. supporting potential for broad regional metal enrichment across northern Canada. The highly combustible nature of these black shale deposits will cause development challenges, however. As well, metals are now being recycled into the otherwise modern pristine Arctic environment, generating hyper acidic waters (recording negative pH values) with metal concentrations orders of magnitude greater than safe drinking levels. Any potential development would face significant challenges.