ReaOs dating of sulphide inclusions zonally distributed in single Yakutian diamonds: Evidence for multiple episodes of Proterozoic formation and protracted timescales of diamond growth

• Published in: Geochimica et cosmochimica acta 2013-11, Vol.120, p.363-394
• Main Authors: Vries, D F, Pearson, D G, Bulanova, G P, Smelov, A P, Pavlushin, AD, Davies, G R
• Format: Article
• Language: English
• Subjects: Agglomeration; Carbon isotopes; Concentration (composition); Dating; Diamonds; Inclusions; Mantle; Sulfides
• ISSN: 0016-7037
• DOI: 10.1016/j.gca.2013.06.035

The timing of diamond formation in the Siberian lithospheric mantle was investigated by ReaOs isotope dating of sulphide inclusions from eclogitic and lherzolitic diamonds from the Mir, 23rd Party Congress and Udachnaya kimberlite pipes in Yakutia. The diamonds contained multiple sulphide inclusions distributed over their core-to-rim zones. Cathodoluminescence, carbon isotope and nitrogen aggregation studies demonstrate that the diamonds are zoned and that the distinct zones are associated with different diamond growth episodes. There are coherent relationships between carbon isotope composition, nitrogen concentration and aggregation state of the diamond hosts, and major and trace element compositions, ReaOs compositions and initial Os isotope ratios of the included sulphides. This suggests that the different diamond and sulphide populations formed at different times from fluids/melts with different chemical compositions. Based on the ReaOs isochron ages and the nitrogen aggregation states we conclude that the sulphides are co-genetic with their diamond hosts.