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TitleIndicator mineralogy of kimberlite boulders and sand samples from the Lac Baby and Sharp Lake eskers, Lake Timiskaming kimberlite field, western Quebec and northeastern Ontario
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorMcClenaghan, M BORCID logo; Kjarsgaard, I M; Kjarsgaard, B AORCID logo; Russell, H A JORCID logo
SourceGeological Survey of Canada, Open File 5050, 2006, 21 pages; 1 CD-ROM, Open Access logo Open Access
LinksCanadian Database of Geochemical Surveys, downloadable files
LinksBanque de données de levés géochimiques du Canada, fichiers téléchargeables
PublisherNatural Resources Canada
Documentopen file
MediaCD-ROM; digital; on-line
RelatedThis publication is related to Mineral chemistry database for kimberlite, surficial sediments and kimberlite boulders from the Lake Timiskaming and Kirkland Lake kimberlite fields, Ontario and Quebec
File formatreadme
File formatdoc (Microsoft Word); pdf (Adobe Acrobat Reader v.5.0 or later); xls (Microsoft Excel 2000)
ProvinceOntario; Quebec
NTS31M/05; 31M/06; 31M/11; 31M/12
AreaNew Liskeard; Haileybury; Cobalt; Lake Timiskaming; Sharp Lake; lac Baby; Montreal River; Ottawa River; lac des Quinze; Notre-Dame-du-Nord; Ville-Marie
Lat/Long WENS-80.0000 -79.1667 47.6667 47.2500
Subjectsgeochemistry; surficial geology/geomorphology; economic geology; esker geochemistry; eskers; kimberlites; pipes; plutonic rocks; igneous rocks; glaciofluvial deposits; sands; boulders; pebble lithology; heavy minerals; heavy mineral analyses; ilmenite; chromite; garnet; clinopyroxene; olivine; perovskite; diopside; lherzolites; websterites; pyroxenites; eclogites; diamond; paragenesis; peridotites; harzburgites; tills; ice transport directions; fluvial transport; mineral exploration; source areas; Archean; carbonates; petrography; pyrope; orthopyroxene; Lake Timiskaming kimberlite field; Guigues kimberlite; SC118 kimberlite; Notre-Dame-du-Nord kimberlites; Sharp Lake pit; Gowganda Formation; Lorrain Formation; Phanerozoic; Cenozoic; Quaternary; Paleozoic; Precambrian
Illustrationssketch maps; photographs; tables; plots; pie charts; ternary diagrams
ProgramTargeted Geoscience Initiative (TGI-1), 2000-2003
Released2006 01 01
AbstractSix kimberlite boulders and 20 sand samples were collected from the Sharp Lake and Lac Baby eskers in the Lake Timiskaming kimberlite field of northeastern Ontario and northwestern Quebec. The boulders were processed to recover heavy mineral concentrates from which grains of Mg-ilmenite, chromite, garnet, clinopyroxene, olivine, and perovskite were picked, counted, and analyzed by electron microprobe. Of the three boulders from the Sharp Lake esker, two boulders (SD-029, SD-030) were heavily altered and did not contain many kimberlite indicator mineral grains. A third boulder from this locality (SD-040) yielded abundant indicator minerals dominated by Mg-ilmenite, Cr-diopside, and garnet. The SD-040 boulder contains diverse garnet and diopside populations, e.g. from lherzolite, sheared lherzolitic, wehrlite, websterite/pyroxenite, eclogite, and megacryst parageneses. Of particular interest are 22 grains of orange garnet recovered from this small boulder (0.6 kg sample weight), which are of potentially diamondiferous Group I eclogite paragenesis. Based on Mg-ilmenite compositions of this boulder, its source is not among the known kimberlites in the Lake Timiskaming field.
Three boulders from the Lac Baby esker contain abundant fresh olivine. Two of the three boulders (SD-041 and SD-043) have very similar indicator mineral abundance and composition, which closely resemble garnet and Mg-ilmenite compositions from the Guigues kimberlite 10 km upstream. They contain high proportions of Mg-ilmenite and garnet, but very little Cr-diopside and chromite. Eclogite garnet grains occur in these two boulders, several of which show the compositional characteristics of potentially diamondiferous Group I eclogite garnets. A third boulder (SD-042) contains only peridotite (wehrlite, lherzolite, and harzburgite) garnets, as well as chromite, Cr-diopside, and comparatively little Mg-ilmenite. Although the garnet compositions show similarities to those of the Notre-Dame-du Nord kimberlites, the Mg-ilmenite compositions are not similar. Its indicator mineral compositions are also different from those of the other two boulders and those of the recently discovered SC118 kimberlite northeast of Lake Timiskaming, suggesting this boulder is derived from an unknown kimberlite.
The sand samples were processed to recover indicator minerals for visual counting only. Samples from the Sharp Lake pit contain <300 indicator mineral grains/10 kg, while samples from five sites along the Lac Baby esker contain >10,000 grains/10 kg. The high indicator mineral abundance combined with the presence of numerous kimberlite fragments in the Lac Baby esker suggests that subglacial meltwater that deposited the Lac Baby esker directly eroded a kimberlite. The much lower indicator mineral grain contents at Sharp Lake suggest that the kimberlite boulders found in this pit are eroded from till, and thus have undergone at least two phases of transport, glacial transport to the southeast or south followed by glaciofluvial transport southward.

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