Diamonds and their formation: Characterization of diamonds from the Buffalo Head Hills, Alberta, and, Metasomatism recorded by garnet inclusions from the De Beers Pool, South Africa.

摘要

This thesis encompasses the study of two principally different types of diamond source regions. The Buffalo Hills represent an unconventional diamond deposit located within the Proterozoic Buffalo Head Terrane. Diamonds from kimberlite pipes K11, K91 and K252 are predominantly of eclogitic paragenesis. Diamond formation occurred in multiple phases under both lithospheric---supported by the presence of Type IaA to IaAB diamonds and sublithospheric conditions---indicated by the presence of majorite and abundance of Type II and Type IaB diamonds. The De Beers Pool mines, located on the Archean Kaapvaal Craton, are the world's classical primary diamond deposit. Garnet inclusions in De Beers Pool diamonds represent the oldest, most depleted mantle samples available and constrain mantle compositions in the Archean. Combined with xenolith studies they indicate increasing fertility of the lithospheric mantle over time. Their re-enriched trace element signatures indicate an intimate association between metasomatism and diamond formation.