Re-Os dating of micrometric Os-rich alloys and sulfides in mantle xenoliths from the Slave Craton: implication for craton formation processes and the Early Earth evolution

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Archean cratons, the oldest pieces of continents preserved at the Earth’s surface, recorded the geological processes that shaped our planet early during its evolution. Their survival is partly due to their chemically buoyant and mechanically strong mantle roots. While mantle roots of the Kaapvaal, Siberia and Greenland cratons were suggested to have formed by lithospheric stacking via subduction, the formation process of the mantle root of the Slave Craton (SC) is still debated. This project aims to obtain firm age constraints on the SC mantle root, determine its P-T-t picture in order to constrain its formation process(es) and understand the early Earth dynamics and thermal history. These objectives will be achieved by coupling “state of the art” Re-Os dating and highly siderophile element (HSE) analyses in Os-host minerals (i.e. alloys, sulfides) in 4 mantle xenolith suites from the SC. In-situ Re-Os and HSE data will be acquired by ultra-sensitive inductively coupled plasma mass spectrometry (ICP-MS) after micro-drilling, chemical digestion using a high-performance HP digestion device (Anton Paar HPA-S) for efficient attacks of refractory alloys and HT sulfides and ultra-low blank chemistry; and by ultra-sensitive laser-ablation ICP-MS.