Re-Os geochronology for sulfides and organic-rich sediments

Rhenium and osmium are both siderophilic and chalcophilic, exhibiting a strong affinity for organic-rich materials. This makes the Re-Os chronometer a valuable complement to geochronometers based on lithophile elements. In this review, we begin by discussing how the elemental abundances and isotopic compositions impact sample selection, analytical strategy, and data interpretation. We then provide an overview of how ¹⁸⁷Os/¹⁸⁸Os ratios can be used to trace geological processes, followed by a summary of the analytical protocols commonly used in Re-Os geochemistry. We also examine key challenges in isochron dating, including the identification and avoidance of pitfalls such as mixing lines, and inherited initial slopes. We further demonstrate that petrographic and geochemical studies can be very helpful for accurately dating sulfides with contrasting initial ¹⁸⁷Os/¹⁸⁸Os values and/or ages. With state-of-the-art Re-Os dating technique reaching precisions up to 0.05% for molybdenites and 1% for organic-rich sedimentary rocks, it is now possible to resolve the rapid and episodic nature of ore formation, and to investigate the dynamics of environment-life coevolution with unprecedented detail. We conclude this review by outlining future directions for Re-Os geochronology, including developing imaging-guided Re-Os dating techniques for organic-rich sediments, sharpening the in situ Re-Os dating method, and fully integrating the Re-Os geochronometer into the EarthTime initiative.