Sulphide survival and diamond genesis during formation and evolution of Archaean subcontinental lithosphere: A comparison between the Slave and Kaapvaal cratons

Sulphide inclusions from 35 eclogitic and 7 peridotitic diamonds from the Diavik kimberlites in the central Slave craton have been characterized to address questions of diamond age and craton formation. Eclogitic sulphide inclusions occur in diamonds with mantle-like delta C-13 (-4.94 +/- 0.72 1 sigma) and low N aggregation states (%N as B=8.2 +/- 10.0, average N contents of 720 ppm) indicative of relatively low mantle residence temperatures. A 1.86 +/- 0.19 Ga Re-Os age array for eclogitic sulphides with suprachondritic initial Os-187/Os-188 of 0.13 (+/- 0.10) indicates a close temporal link between eclogitic diamond formation, eclogite emplacement and collisional events affecting the Slave craton. Sulphides in peridotitic diamonds plot on older. previously established 3.3 and 3.5 Ga isochrons, consistent with higher average N aggregation states (similar to 20%) despite lower N contents (similar to 230 ppm) for their host diamonds compared to eclogitic diamonds.