Geo-Note 2005-06

Evidence for kimberlite-sourced bentonite in Late Cretaceous strata of north-central Alberta: A bedrock characterization tool to aid diamond exploration

Executive Summary

As part of an initiative to study kimberlite-host rock relationships in northern Alberta, seven separate bentonite horizons were collected for study from sedimentary cores obtained by past testing of kimberlite targets in the Buffalo Head Hills kimberlite field of north-central Alberta. Physical and geochemical evidence has been presented to conclude that two bentonite samples collected during the investigation of sedimentary cores in the vicinity of the Buffalo Head Hills kimberlite field have been sourced from kimberlite. The presence of micaceous flakes and carbonate-enrichment in the form of calcite and dolomite help to characterize kimberlitic bentonite in hand sample. Geochemical data, particularly immobile elements, provide strong evidence for the source magma and clearly separate the kimberlitic bentonite from intermediate to felsic volcanic parental material typical of bentonite in the Alberta basin. Alternatively, the two bentonites have similar geochemical compositions to whole rock kimberlite from the northern Alberta kimberlite province.

Place Keywords: 84b; buffalo head hills; northern alberta

Theme Keywords: bentonite; geochemistry; kimberlite