Project Leader: Beth McClenaghan

GSC field work in 2002 consisted of several activities, including till sampling for kimberlite indicator mineral studies, groundwater sampling, and soil sampling for selective leach analysis. Backhoe trenches were excavated into the recently discovered BBB kimberlite (Photo 1) in Firstbrook Township. The BBB kimberlite is overlain by only 0.3 to 1.5 m of brown silty sand till containing abundant Paleozoic limestone clasts. Kimberlite and till up- and down-ice were sampled to determine the mineralogical and geochemical signature of the kimberlite and to document the nature of glacial dispersal.

Kimberlite boulders from gravel pits on eskers near Sharp Lake and Lac Baby (Quebec) were collected to determine the source of the kimberlite boulders in these eskers. In addition, 34 sand samples were collected from glaciofluvial eskerine and moraine deposits down ice of known kimberlites. Many of the sampled sites had previously yielded kimberlite material in the pebble to cobble size range. In the Sharp Lake esker, six samples were collected to study changes in heavy mineral concentrations based on sediment facies, stratigraphic position, and distance along the esker. In the Lac Baby area, 29 samples were collected at numerous sites to assess changes in heavy mineral content by sediment facies, stratigraphic position, location in the landscape, and spatially. The sample distribution should also help in answering some questions with respect to the nature of the Lac Baby esker-moraine feature. For more information about these activities, contact: Hazen Russell at GSC-Ottawa.

In July, 2002, groundwater in holes drilled by exploration companies in the 1980's and 1990's was sampled at five kimberlites near Kirkland Lake and Lake Timiskaming: B30, C14, A4, Diamond Lake and 95-2 (Photo 2). These samples were collected to learn about the hydrogeology and geochemistry of groundwater in kimberlites and to develop its use as an exploration tool. Sampling was done using three methods: straddle-packer, double valve pump and Grundfos pump. The waters were measured in the field for pH, oxidation-reduction potential (Eh), dissolved oxygen, electrical conductivity and temperature. Preliminary field results indicate that many pH values are unusually high for natural waters, with pH levels in B30, C14 and A4 as high as 12.45. Field analysis and pump-recovery tests reveal that there may be a link between the hydration of olivine and the production of CH4 (methane), H2 (hydrogen) and groundwater flow. Stable isotopic analyses (H, O, C, and S), alkalinity and major and trace element analyses are currently underway and will assist in determining the geochemical processes at work in kimberlites. This study is being conducted by Jamil Sader and Matt Leybourne, University of Texas at Dallas in collaboration with Stew Hamilton, Ontario Geological Survey. For more information about these activities, download the poster display PDF file or contact: Matt Leybourne, University of Texas at Dallas (mleybo@utdallas.edu).

Soil sampling and SP surveys were conducted over the B30, A4 and 95-2 kimberlites to document the surface geochemical signatures of these kimberlites and the effectiveness of different selective leaches (MMI, Enzyme Leach, ammonimum acetate) in detecting these deeply buried (> 30 m) kimberlites (Photo 3). This study is being conducted in collaboration with Stew Hamilton, Ontario Geological Survey.

Publications in 2002

(available through GSC Bookstore)

McClenaghan, M.B., Kjarsgaard B.A., Kjarsgaard I.M. and Paulen, R.C. 2002: Indicator mineral content and geochemistry of till around the Peddie kimberlite, Lake Timiskaming, Ontario; Geological Survey of Canada, Open File 4262.

McClenaghan, M.B., Kjarsgaard I.M., Kjarsgaard B.A. and Heaman, L.M. 2002: Mineralogy of kimberlite boulders from eskers in the Lake Timiskaming and Kirkland Lake areas, northeastern Ontario; Geological Survey of Canada, Open File 4361.

	Photo 1. Looking south along a backhoe trench excavated north to south across the recently discovered BBB kimberlite, Lake Timiskaming kimberlite field. The green colour at the base of the trench is weathered kimberlite.
	Photo 2. Collecting groundwater samples from a diamond drill hole in the B30 kimberlite, Kirkland Lake kimberlite field.
	Photo 3. Collecting B horizon material from sandy podzolic soils overlying the 95-2 kimberlite, Lake Timiskaming kimberlite field, for selective leach analysis.