Metal fertilization in the crust-mantle transition zone for a fast-spreading ridge environment

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The OmanDP boreholes CM1A and CM2B have cored the harzburgite-dunite-gabbro section in the Wadi Tayin ophiolite massif. Hitherto inaccessible, unexposed crust-mantle transition zone (MTZ) rocks for a fast-spreading paleo-ridge are now available. We study in situ trace element, and osmium isotope compositions of sulfides from those MTZ rocks. Sulfides are especially suitable to study the metal fertilization process because the behavior of siderophile and chalcophile elements is mostly controlled by sulfide phases in sulfur-saturated environments while fluxed from the mantle into the crust. The data will be combined with trace element signatures of olivine and chromite to derive records of multiple recharge episodes and melt evolution events in the MTZ section. Mineral-scale elemental data will add fundamental information to newly determined but also to already published whole rock geochemical and isotope data and thus help to understand magmatic and metasomatic processes within the MTZ. Combination of in situ osmium isotopes and in situ HSE data of identical MTZ sulfides promotes a noble metal fractionation-based framework for a new level of understanding of MTZ dunite formation, nature of the percolating melt and refertilization reactions. Understanding the metal fertilization in the crust-mantle transition zone adds to our knowledge of dynamic magmatic-hydrothermal interactions at fast-spreading ridges and related minerals deposits.