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

太古代克拉通是保存在地球表面最古老的大陆板块，记录了在地球早期演化过程中塑造地球的地质过程。它们的生存部分是由于它们的化学浮力和机械强度强的地幔根。虽然Kaapvaal、西伯利亚和格陵兰克拉通的地幔根被认为是由岩石圈通过俯冲堆积形成的，但奴隶克拉通（SC）的地幔根的形成过程仍然存在争议。该项目旨在获得SC地幔根的确切年龄约束，确定其P-T-t图像，以约束其形成过程，了解早期地球动力学和热历史。这些目标将通过将“最先进的”Re-Os定年技术与SC 4套地幔捕体岩中os宿主矿物（即合金、硫化物）的高亲铁元素（HSE）分析相结合来实现。微钻孔后，超灵敏电感耦合等离子体质谱（ICP-MS）将获得现场Re-Os和HSE数据。化学消解：采用高性能高压消解装置（安东帕HPA-S）高效消解难熔合金和高温硫化物，超低空白化学；超灵敏激光烧蚀ICP-MS。

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.