Enigmatic diamonds in Archean calc-alkaline lamprophyres of Wawa, southern Ontario, Canada

Hydrogen isotope compositions in carbonado diamond: constraints on terrestrial formation

“…7). Green, orange and red cathodoluminescence colours unusual for mantle-derived diamonds but characteristic for carbonados have also been detected in calc-alkaline lamprophyre-related diamond populations (De Stefano et al 2006) and orogenic microdiamonds (Yoshioka and Odasawara 2005), both…”

“…Additionally, the carbonado grains have a smooth, glossy surface that has been interpreted as "fusion crust" formed during a bolide impact (Shelkov et al 1997;Kletetschka et al 2000). The arguments for extraterrestrial origin have been weakened by recent observations published in the last several years: osbornite (TiN) has been shown to form in deep subduction environment (Dobrzhinetskaya et al 2007), deformation lamellae have been produced experimentally at mantle P-T conditions in carbonado diamond ), green and yellow CL colours have been encountered in terrestrial diamonds (De Stefano et al 2006), native metals have been described in kimberlite-hosted diamonds (Jacob et al 2004 and references therein), diamonds with very low carbon isotope compositions (down to -41‰ relative to V-PDB, Cartigny et al 2004;Cartigny 2007Cartigny , 2008De Stefano et al 2009), low aggregation states (Cartigny 2007(Cartigny , 2008Kagi and Fukura 2008) and elevated hydrogen contents (Hayman et al 2005) have been reported from various types of mantle-derived diamonds. The latter observation is important as the hydrogen content of the carbonado diamond can provide new means to investigate its origin.…”

Dynamic cause of marginal lithospheric thinning and implications for craton destruction: a comparison of the North China, Superior, and Yilgarn cratons

“…The thick lithosphere extended to the diamond stability field beneath the Wawa area ( Fig.5B; the southern Superior craton) prior to ~2.7 Ga, as inferred from studies of diamonds in Neoarchean lamprophyres and related volcaniclastic breccias (Stachel et al 2006;De Stefano et al 2006).…”

“…However, they did not have a clear explanation for the specific dynamic reason for the lithospheric thinning. The thick lithosphere extending to the diamond stability field existed beneath this area (the Wawa area; Fig.5B) prior to ~2.7 Ga, which was inferred from studies of diamonds in the Neoarchean lamprophyres and related volcaniclastic breccias (Stachel et al 2006;De Stefano et al 2006). However, detailed geophysical data presented in section 4.2 shows that the southern Superior craton does not have high seismic velocities indicative of lithosphere thicker than 150 km (Frederiksen et al 2007;Faure et al 2011).…”

C and N isotope compositions of diamonds from the calc-alkaline lamprophyres of Wawa (Superior craton)

“…Diamonds from the calc-alkaline lamprophyres of Wawa are unique in several aspects and have been object of detailed studies in the recent years (e.g. De Stefano et al, 2006;Stachel et al, 2006). The peculiarities of this diamond suite include the ancient age of the host rocks (2.7 Ga, Wyman and Kerrich, 1993), the occurrence in an orogenic setting, the predominance of red-orange and yellow cathodoluminescence colours, the presence of peridotitic and eclogitic syngenetic mineral inclusions within the same diamond, and a disequilibrium between mineral inclusions and its diamond host (De Stefano et al, 2006).…”