Diamond Exploration: Kirkland Lake Kimberlites |
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Mineralogical and geochemical signatures of kimberlites in glacial sediments, Kirkland Lake, Ontario B30 Kimberlite Pipe
The B30 pipe, also known as the Nickila Lake pipe, intruded Archean mafic and intermediate volcanic and Paleozoic carbonate rocks approximately 156 Ma ago. The subcropping surface of the pipe consists of kimberlite breccia and is approximately 250 m by 400 m. The upper 10 m of the pipe has been weathered to a friable and soft, bluish-green clay. The pipe is covered by a thick sequence of glacial sediments consisting of 10 to 20 m of till overlain by 40 m of fine-grained glaciolacustrine and glaciofluvial sediments. Glacial sediments are thickest directly over the pipe where the kimberlite has been eroded 24 m below the surrounding bedrock. The relative abundance of indicator minerals in the B30 kimberlite in decreasing order is: pyrope > Mg-ilmenite > chromite > Cr-diopside. Indicator minerals from the B30 pipe can be traced a minimum distance of 800 m southwest and 200 m south of the pipe in till. Till overlying kimberlite is geochemically anomalous, but till immediately down-ice is not. Results for the B30 pipe have been published in GSC Open File 3295 (McClenaghan et al., 1996)
Location map
Cross-section
B30 kimberlite breccia
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