Information Series 133

Author(s) Date 2005-12-14

Poster submission to the 2004 Calgary Mining Forum. The Clear Hills oolitic ironstone was initially discovered during the 1920s, re-discovered in the early 1950s, and extensive exploration and government geoscience work was conducted locally in the southern and eastern Clear Hills region from the late 1950s into the early 1970s. Since then, only sporadic exploration and little government geoscience work has been done. As a result of the 1950s to 1970s work, a resource of at least 1.1 billion tonnes grading 32% to 36% iron was identified (Bertram and Mellon, 1975). The oolitic ironstones are in the Bad Heart Formation which, based on biostratigraphic work done by Dr. C. Collom (2000) along the Smoky River, is of late Coniacian age (~86.5 to 85.5 Ma). Hamilton (1980) reported the ironstone comprises a dark brown to green-black, ferruginous oolitic zone in a bed that is up to about 10 m thick at Rambling River on the eastern margins of the Clear Hills. Prior work has indicated the oolitic horizon is thickest in the northeast near Rambling River, but thins to the west to a zero edge as the oolitic ironstone passes laterally into equivalent Bad Heart Formation siltstone-sandstone. It has been suggested that the Clear Hills deposit is Minette-type oolitic ironstone; it consists of densely packed ooliths with the matrix comprised of illite and nontronite imbedded in a ferruginous opaline and sideritic cement.

During summer 2004, the AGS re-visited and precisely located many of the reported Bad Heart and oolitic ironstone exposures that were identified by Kidd (1959). At selected sites, geological examinations and systematic rock chip sampling were performed. In total, 151 rock samples (including 7 duplicates and 7 standards) were collected and submitted for geochemical analyses. These samples were collected from 5 sites in the southern Clear Hills, 4 sites near the hamlets of Spirit River and Wanham, and 15 sites along the Smoky River. The primary intent of this sampling is to provide a preliminary lithogeochemical characterization of the oolitic ironstones (based on oxidized surface material) to supplement previous lithogeochemical work reported by Olson et al. (1999) and some other workers. It is anticipated that this new lithogeochemical information will be released sometime during 2005.

During the latter half of 2004, the AGS collaboratively compiled (with some financial support from Clear Hills Iron Ltd.) digital information about ironstone and coal in the Clear Hills-Smoky River region from publicly available sources. The sources included selected assessment reports; oil, gas and water wells; exploratory coal holes and some other documents. These data will be publicly released during the first half of 2005 as AGS Geo-Note 2005-01. The digital data and information in this Geonote are being released as two CDs that will include an ArcExplorer project to facilitate viewing selected data without the need for purchase of any software.

With respect to potential coal resources in the Clear Hills region, Alberta Energy and Utilities Board (Dec. 1993 Reserves of Coal Report) identified an initial in-place resource estimate of about 240 million tonnes of lignitic A coal in two seams in late Late Cretaceous Wapiti Formation. During winter 2004-2005, Sneddon has been working up the coal resources in the Clear Hills Region. This work has indicated there are several potential coal targets and these exist in sub-basins that are possibly separated by several known and inferred faults. The coal is believed to occur as stacked, discontinuous seams of varying quality. As a result, exploration will be needed to (a) identify those coal resources that are both of highest quality and largest size and (b) identify those locales in the Clear Hills region where there is spatial overlap of mineable resources of ironstone as well as potentially mineable resources of coal.

NTS Keywords

Weiss, J.A., Olson, R.A. and Sneddon, D.T. (2005): Clear Hills ironstone and coal resources - 2004 digital compilation and some geochemical and geological highlights from 2004 fieldwork; Alberta Energy and Utilities Board, EUB/AGS Information Series 133, 5 p.