Spencer Killins HBSc thesis abstract

A kimberlite indicator minerals suite from above the DO18 kimberlite has been analyzed both texturally and chemically resulting in identified kimberlitic olivine, garnet, clinopyroxene, spinel, and ilmenite. Through a detailed glacial analysis of the Lac de Gras region containing DO18, the indicator suite is not limited to an origin from DO18. Northern kimberlite pipes have indications of kimberlite indicator trains following a southward ice flow direction, towards DO18. Textural evidence from the grains supports kimberlitic material that underwent minimal transport, as the grains are dominantly euhedral. Through major element chemical analysis, all minerals indicate an origin from a diamondiferous kimberlitic grains source. This suite is likely derived from a single kimberlite as the total chemical variation is limited for each mineral phase and along compositional trends. All indicators are a reflection of source from within the subcontinental lithospheric mantle beneath the Lac de Gras region, defined by both peridotitic and eclogitic compositions. Of the suite, garnet and olivine strongly indicate metasomatism to the subcontinental lithospheric mantle through increased titanium content and average forsterite value of 92, this corresponds to the rapid low angle Farallon plate subduction, dehydration, and partial melting.