Exploration and Discovery of the Chidliak Kimberlite Province, Baffin Island, Nunavut: Canada’s Newest Diamond District

Abstract

Sixty-two kimberlites discovered on Hall Peninsula, southern Baffin Island, Nunavut between 2008 and September 2011 comprise Chidliak, the most recently discovered kimberlite province in Canada. These discoveries were the result of traditional kimberlite exploration techniques used in glaciated terrains, including kimberlite indicator mineral (KIM) sampling and analysis, ground and airborne magnetic and electromagnetic geophysical surveys, and ground prospecting and drilling. Capacitively coupled resistivity ground surveys and comprehensive KIM classification and interpretation techniques also played a significant role. Both sheet-like and larger pipe-like bodies have been discovered. The sheet-like bodies are mainly steeply dipping hypabyssal kimberlites, which may contain basement xenoliths. The majority of the pipe-like bodies have pyroclastic or apparently coherent kimberlite infill containing sedimentary xenoliths derived from now-eroded Paleozoic strata in addition to basement xenoliths. The presence of these sedimentary xenoliths, along with other textural features, suggests that at least some of the apparently coherent kimberlites are not intrusive but are extrusive, either effusive or clastogenic in origin. Many of the kimberlites manifest as strong remanently magnetized 0.5–2.0 ha bodies that are expressed as magnetic high and low anomalies with associated weak and shallow conductivity responses. Bodies dominated by pyroclastic kimberlite infill can have neutral to weak magnetic signatures, appear to be more conductive, and can be much larger (up to 4–5 ha) than those with dominantly coherent kimberlite infill. Perovskite U–Pb dating of 25 of the kimberlites indicates magmatism spanned a period of approximately 18 million years, from 156 to 138 Ma (Late Jurassic to Early Cretaceous).