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

在瓦迪塔因蛇绿岩地块的方辉橄榄岩-纯橄榄岩-辉长岩剖面中，由OmanDP钻孔CM1a和CM2b取芯。到目前为止，无法接触到的、未暴露的壳幔过渡带(MTZ)岩石现在可以用于快速扩张的古山脊。我们对这些岩石中硫化物的微量元素和Os同位素组成进行了研究。硫化物特别适合于研究金属成矿过程，因为在硫饱和环境中，亲铁元素和亲硫元素的行为主要受硫化物相控制，并从地幔流入地壳。这些数据将与橄榄石和铬铁矿的微量元素特征相结合，得出MTZ剖面中多个补给幕和熔体演化事件的记录。矿物尺度的元素数据将为新确定的以及已经公布的全岩地球化学和同位素数据增加基本信息，从而有助于了解MTZ内的岩浆和交代过程。同一MTZ硫化物的原位Os同位素和原位HSE数据相结合，促进了一个基于贵金属分馏的框架，以更高水平地理解MTZ纯陨石的形成、渗流熔体的性质和参考反应。了解壳幔过渡带中的金属成矿作用有助于我们了解快速扩张的海脊和相关矿藏中的岩浆-热液动态相互作用。

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.