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TitleKimberlite and base metal indicator minerals in glacial sediments of northern Alberta, Canada
AuthorPaulen, R C; Plouffe, A; Smith, I R
SourceExplore no. 138, 2008 p. 1-7
Alt SeriesEarth Sciences Sector, Contribution Series 20070588
NTS84E; 84F; 84K; 84L; 84M; 84N
AreaZama Lake; Peace River; Hay River; Cameron Hills; Clear Hills; Buffalo Head Hills; Caribou Mountains; Bistcho Lake
Lat/Long WENS-120.0000 -116.0000 60.0000 57.0000
Subjectssurficial geology/geomorphology; economic geology; indicator elements; kimberlites; diamond; exploration; exploration methods; mineral exploration; base metals; heavy minerals; heavy mineral analyses; glacial deposits; tills; till analyses; dispersal patterns; sediment dispersal; ice flow; indicator minerals; Cenozoic; Quaternary
Illustrationsphotomicrographs; location maps
The source of the KIMs is unknown. Plouffe et al. (2007) suggested that samples with 1 or 2 KIMs within the Zama Lake-Zama City region may represent background concentrations for a region located 100's of kilometres from known kimberlites in the Northwest Territories, in the general up-ice direction. On the other hand, samples containing 6 to 9 KIMs are considered anomalous and might reflect the presence of an unknown kimberlitic source closer to this region.

The source of the sphalerite and galena grains in till remain unknown. Mineral colour, composition, surficial mapping and ice-flow studies in the region indicate that it is unlikely that the sphalerite-bearing till is the product of long-distance glacial transport from the Pine Point Mississippi Valley Type Zn-Pb deposits on the southern shore of Great Slave Lake, Northwest Territories. Aside from the regional ice-flow history, there are several factors that argue against the sphalerite anomalies being the product of long-distance glacial transport, comminution, and deposition of erratic material from the Pine Point area, and instead favour a proximal bedrock source. First, the nine sample sites with high sphalerite grain counts (and eleven with lesser concentrations) are situated within a geographically restricted area north of Zama Lake. Second, geochemical analyses of the silt and clay-sized fraction of the tills does not reveal proportionally elevated concentrations of lead and zinc, suggesting that glacial comminution of sand-sized sphalerite and galena has been limited. Third, close examination of the mineral grains shows that some grains have strong primary crystal structure and subangular to angular morphologies which would not have likely survived extensive glacial erosion and transport. Lastly, the sphalerite grains have dissimilar optical and chemical properties than the ore studied at Pine Point by Kyle (1981).

Conjecture that the sphalerite grains found in the glacial sediment survey do not represent long-distance transport of erratic material and instead were eroded from an unknown proximal bedrock source suggest that we have identified a potential for zinc mineralization in the Cretaceous shale bedrock. The anomaly is situated in close proximity to the Great Slave Lake Shear Zone (Burwash et al., 1994; see also Figure 6). Recent research on lead and zinc in northern Alberta formation waters (Hitchon, 2006) concluded that exploration should focus on these shear zones and faults, up which geothermal fluids might have migrated. Future Pb and S isotopic analyses of the galena and sphalerite grains may resolve their provenance, and shed further light on mineral potential in the study area. These indicator mineral results highlight the potential for the discovery of one or more zinc-rich base metal deposits hosted within Cretaceous shale of northwestern Alberta.