Abstract Nitrogen is a major and essential component of Earth's atmosphere, yet relative to other volatile elements, there are relatively few experimental constraints on the pathways by which nitrogen cycles between Earth's interior and exterior. We report mineral-melt and mineral-fluid partitioning experiments to constrain the behavior of nitrogen during slab dehydration and sediment melting processes. Experiments reacted rhyolitic melts with silicate and oxide minerals, in the presence of excess aqueous fluid, over temperatures between 725-925 °C and pressures between 0.2 and 2.3 GPa. Oxygen fugacity ranged between iron metal saturation (∼NNO-5) to that in excess of primitive arc basalts (∼NNO+2). Our experiments demonstrate that hydrous fluid is the preferred phase for nitrogen over minerals (biotite, K-feldspar, and amphibole) and rhyolitic melts across all conditions explored. Relatively large effects of pressure (Δlog( D m e l t − f l u i d N )/Δ(GPa/K) = 761 ± 68 (1σ), Δlog( D b i o t i t e − f l u i d N )/Δ(GPa/K) = 462 ± 169) and moderate effects of oxygen fugacity ( Δ l o g ( D m e l t − f l u i d N ) / Δ NNO = -0.20 ± 0.04, Δlog ( D b i o t i t e − f l u i d N ) / Δ NNO = -0.10 ± 0.04) modulate partitioning of nitrogen. We further document negligible partitioning effects related to mineral composition or Cl content of hydrous fluid. Of the minerals investigated, biotite has the largest affinity for N and should control the retention of N in slabs where present. Application of partitioning data to slab dehydration PT paths highlights the potential for highly incompatible behavior ( D b i o t i t e − f l u i d N D b i o t i t e − f l u i d N > 0.1). We find that slab melting is less effective at extracting N from slabs than fluid loss, at least under oxidized conditions (NNO+1). Ultimately, the conditions under which slabs lose fluid strongly affect the distribution of nitrogen between Earth's interior and exterior.

中文翻译：

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温暖和氧化的板块限制了氮向地幔的注入效率

摘要 氮是地球大气的主要和必不可少的组成部分，但相对于其他挥发性元素，氮在地球内部和外部之间循环的路径的实验限制相对较少。我们报告了矿物熔体和矿物流体分配实验，以限制板坯脱水和沉积物熔化过程中氮的行为。实验使流纹岩熔体与硅酸盐和氧化物矿物在过量含水流体存在下在 725-925°C 之间的温度和 0.2 和 2.3 GPa 之间的压力下反应。氧逸度介于铁金属饱和度 (~NNO-5) 到超过原始弧玄武岩 (~NNO+2) 之间。我们的实验表明，与矿物（黑云母、钾长石、和闪石）和流纹岩在探索的所有条件下熔化。相对较大的压力影响（Δlog（D 熔体 - 流体 N ）/Δ（GPa/K）= 761 ± 68（1σ），Δlog（ D 黑云母 - 流体 N ）/Δ（GPa/K）= 462 ± 169）和氧逸度的中等影响（Δ log（D 熔体 - 流体 N ）/Δ NNO = -0.20 ± 0.04，Δlog（ D 黑云母 - 流体 N ）/Δ NNO = -0.10 ± 0.04）调节氮的分配。我们进一步记录了与含水流体的矿物成分或 Cl 含量相关的可忽略的分配效应。在所研究的矿物中，黑云母对 N 的亲和力最大，应控制 N 在板坯中的保留。将分区数据应用于平板脱水 PT 路径突出了高度不相容行为的可能性（D 黑云母 - 流体 ND 黑云母 - 流体 N > 0。1）。我们发现，至少在氧化条件 (NNO+1) 下，板坯熔化在从板坯中提取 N 的效率低于流体损失。最终，板块失去流体的条件强烈影响地球内部和外部之间氮的分布。