The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcements called the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The SDLRC Blog is a guest commentary by an industry expert about articles, themes and trends in recent issues of the SDLRC.
Comments by Brooke Clements
Brooke Clements is President and CEO of Craton Minerals Ltd., a Vancouver-based private diamond exploration company focused on discovering North America's next diamond district. He is also President of JBC Ventures Ltd., a consulting company specializing in mineral exploration and community and government relations. From 2007 to 2015 he was President of Peregrine Diamonds Ltd. where he led the team that discovered the Chidliak diamond district on Baffin Island in the Canadian Arctic. Before that, Brooke was Vice President, Exploration for Ashton Mining of Canada Inc. Under his leadership, Ashton and their partner SOQUEM discovered the Renard diamond district in Quebec where the Renard Diamond Mine commenced production in 2016. From 1982 to 1997, Brooke was an Exploration Geologist and Regional Manager for Exmin Corporation where he conducted diamond exploration programs throughout the United States. He holds a BSc in Geology from Indiana University and an MSc in Economic Geology from the University of Arizona.
Brooke Clements has volunteered to highlight the scientific articles that caught his attention in the monthly reference compilations. The opinions expressed are solely his and he can be reached at .
This is an interesting study of the basement around the Mid-Continent rift in Canada and the USA. Seismic data is used to make high-resolution Rayleigh wave
phase-velocity maps. Strong isotropic features are noted related to the Trans-Hudson Orogen, the Superior craton and the Mid-Continent Rift. They conclude that the oldest cratonic lithosphere may have been formed under a different or pre-plate tectonic regime which was later modified by orogenesis around the edges, hotspot passage, rifting and magmatism. The authors ask an interesting question that diamond explorers have pondered. Loosely quoted, "Do accreted terranes and blocks bring their own lithosphere with them, which is also accreted, or is the lithosphere of these smaller terranes destroyed, and must re-form?" Figure 1 is a nice tectonic map of north-central North America.
Artisanal and small scale mining activity is increasing in sub-Saharan Africa and South America and approximately 20 million people are involved globally. The authors studied satellite data from the Prieska region of the northern Cape Province of South Africa where the semi-precious stone Tiger's Eye is mined by artisanal miners. Decreases in vegetation and increases in areas with bare soil tracked the growth of mined areas.
Summary of the Bunder lamproite cluster in northern India where Rio Tinto came close to developing a diamond mine. The authors find that the Archean mantle lithospheric setting of Bunder is similar to a few prolific diamond producing areas.
The lithospheric mantle beneath Archean cratons is refractory and thick compared to younger continental lithosphere. Geochemical data from Archean igneous suites suggests that mantle convection drove crustal thickening in the late Archean during continent formation.
Xenoliths and xenocrysts from 1.15 billion year old kimberlite dykes in the Certac gold mine in Desmaraisville region of Quebec are studied in detail. The first kimberlites were found in this region in the 1950s. No diamonds have been recovered from these dykes, there are no indicator minerals from the diamond inclusion field and the deepest equilibration depth of a mantle xenolith was 131 km, above the diamond stability field.