| Title | Indicator mineralogy of kimberlite boulders and sand samples from the Lac Baby and Sharp Lake eskers, Lake Timiskaming kimberlite field, western Quebec and northeastern Ontario |
| Download | Downloads |
| |
| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | McClenaghan, M B ;
Kjarsgaard, I M; Kjarsgaard, B A; Russell, H A J |
| Source | Geological Survey of Canada, Open File 5050, 2006, 21 pages; 1 CD-ROM, https://doi.org/10.4095/221567  Open Access |
| Links | Canadian Database of Geochemical Surveys, downloadable
files
|
| Links | Banque de données de levés géochimiques du Canada,
fichiers téléchargeables
|
| Year | 2006 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | CD-ROM; digital; on-line |
| Related | This 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 format | readme
|
| File format | doc (Microsoft Word); pdf (Adobe Acrobat Reader v.5.0 or later); xls (Microsoft Excel 2000) |
| Province | Ontario; Quebec |
| NTS | 31M/05; 31M/06; 31M/11; 31M/12 |
| Area | New 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 |
| Subjects | geochemistry; 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 |
| Illustrations | sketch maps; photographs; tables; plots; pie charts; ternary diagrams |
| Program | Targeted Geoscience Initiative (TGI-1), 2000-2003 |
| Released | 2006 01 01 |
| Abstract | Six 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. |
| GEOSCAN ID | 221567 |
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