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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Coupled ~(186)Os–~(187)Os enrichments in the Earth's mantle – core–mantle interaction or recycling of ferromanganese crusts and nodules?
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Coupled ~(186)Os–~(187)Os enrichments in the Earth's mantle – core–mantle interaction or recycling of ferromanganese crusts and nodules?

机译：地球地幔中的〜（186）Os ~~（187）Os富集耦合-铁锰结壳和结核的核-幔相互作用或循环利用？

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~(186)Os enrichments in volcanic rocks and peridotite-derived iridosmine grains have been attributed to contributions from Earth's outer core to the mantle, and apparently constrain the scale of mantle convection and an early timing for inner–outer core segregation more than 3.5 Gyr ago. Here, we highlight that marine ferromanganese crusts and nodules are characterised by high Pt/Os ratios and Pt–Os contents that develop much larger ~(186)Os excesses over geological time (≥0.2%/Gyr) than those hypothesised for Earth's outer core (<0.005–0.01%/Gyr). ~(187)Os/~(188)Os ratios in ferromanganese crusts are radiogenic due to sequestering of continental Os from seawater. Similarly, ancient ferromanganese materials may have had ~(186)Os excesses (>0.1%) as a result of high Pt/Os ratios in continental crust, even prior to in-growth of ~(186)Os after formation due to their high Pt/Os ratios. Past recycling of small amounts of these materials into the Earth's mantle will produce coupled ~(187)Os–~(186)Os excesses and little change in Re and platinum-group-element concentrations, as observed in Hawaiian picrites, and in contrast to the predicted result of outer core addition to the mantle. ~(187)Os and ~(186)Os enrichments in the Hawaiian mantle source are potentially consistent with it comprising recycled oceanic lithosphere, pelagic sediments and ferromanganese materials, and questions the notion that Os isotopes can be used to uniquely identify core–mantle interactions and the depth at which mantle sources for volcanism originate.
机译：〜（186）Os富集在火山岩和橄榄岩中的iridosmine颗粒归因于地球外核对地幔的贡献，并且显然限制了地幔对流的规模和内外核偏析的早期时间超过3.5 Gyr前。在这里，我们强调指出，海洋铁锰结壳和结核的特征在于高的Pt / Os比和Pt-Os含量，在地质时期内（〜0.2％/ Gyr）产生的〜（186）Os过量比假设的地球外核大（<0.005-0.01％/ Gyr）。锰铁结壳中〜（187）Os /〜（188）Os的比率是放射源的，这是由于海水中螯合了大陆中的Os。同样，由于大陆壳中高的Pt / Os比，古老的锰铁材料可能存在〜（186）Os过量（> 0.1％），甚至由于形成原因而在〜（186）Os内生长之前Pt / Os比。过去在夏威夷地幔中观察到，将少量这些物质再循环到地球地幔中会产生耦合的〜（187）Os ~~（186）Os过量，Re和铂族元素浓度几乎没有变化。地幔外核的预测结果。夏威夷地幔源中〜（187）Os和〜（186）Os的富集可能与包括再循环海洋岩石圈，浮游沉积物和铁锰材料的富集一致，并质疑Os同位素可用于唯一识别核心-地幔相互作用的概念以及火山活动地幔起源的深度。

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