An olivine-melt thermometer based on the partitioning of Ni (⁠DNiOl/liq⁠) was hypothesized by Pu et al. (2017) to have a negligible dependence on dissolved water in the melt (and pressure variations from 0–1 GPa), in marked contrast to thermometers based on DMgOl/liq⁠. In this study, 15 olivine-melt equilibrium experiments were conducted on a basaltic glass starting material (9.6 wt% MgO; 353 ppm Ni) to test this hypothesis by comparing the effect of dissolved H2O in the melt on DMgOl/liq and DNiOl/liq on the same set of experiments. Results are presented for six anhydrous experiments at 1 bar, two anhydrous experiments at 0.5 GPa, and seven hydrous experiments at 0.5 GPa. Analyzed olivine and glass compositions in the quenched run products were used to calculate DMgOl/liq and DNiOl/liq values for each experiment, which in turn permit temperature to be calculated with the Mg- and Ni-thermometers calibrated in Pu et al. (2017) on anhydrous, 1-bar experiments from the literature. The Ni-thermometer recovers the temperatures of all 15 experiments from this study with an average deviation of –3 °C, including those with up to 4.3 wt% H2O dissolved in the melt. In contrast, the Mg-thermometer recovers the anhydrous, 1-bar experimental temperatures within +14 °C on average, but overestimates the hydrous experimental temperatures by +49 to +127 °C, with an average of +83 °C. When the Mg-thermometer of Putirka et al. (2007) is applied, which includes a correction for analyzed H2O (≤4.3 wt%) in the quenched melts of the run products, all experimental temperatures are recovered with an average (±1σ) deviation of +7 °C. The combined results show that DNiOl/liq has a negligible dependence on dissolved water in the melt (≤4.3 wt% H2O), which is in marked contrast to the strong dependence of DMgOl/liq on water in the melt. An understanding of why DNiOl/liq is insensitive to dissolved water, unlike DMgOl/liq⁠, is obtained from spectroscopic evidence in the literature, which shows that Ni2+ (transition metal) and Mg2+ (alkaline earth metal) have distinctly different average coordination numbers (predominantly fourfold and sixfold, respectively) in silicate melts and that fourfold-coordinated Ni2+ is unaffected by the presence of dissolved water in the melt. This difference in coordination number explains why DNiOl/liq and DMgOl/liq each have a different dependence on pressure, anhydrous melt composition, and melt water content. Application of the Ni-thermometer of Pu et al. (2017) to five natural samples from the Mexican arc, for which H2O contents (3.6–6.7 wt%) in olivine-hosted melt inclusions are reported in the literature, leads to temperatures that match those obtained from the Putirka et al. (2007) Mg-thermometer that corrects for analyzed H2O contents. This study demonstrates that a thermometer based on DNiOl/liq can be applied to hydrous basalts at crustal depths without the need to correct for dissolved water content or pressure.

中文翻译：

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基于地壳压力下橄榄石熔融镍分配的新型独立于H2O的温度计的实验评估

Pu等人假设了一种基于Ni（DNiOl /liq⁠）划分的橄榄石熔体温度计。（2017年）对熔体中溶解的水（以及压力变化范围从0–1 GPa）的依赖性可以忽略不计，这与基于DMgOl / liq？的温度计形成鲜明对比。在这项研究中，对玄武岩玻璃原料（9.6 wt％MgO； 353 ppm Ni）进行了15个橄榄熔体平衡实验，通过比较熔体中溶解的H2O对DMgOl / liq和DNiOl / liq的影响来验证这一假设。在同一组实验上。给出了在1 bar下进行的六个无水实验，在0.5 GPa下的两个无水实验和在0.5 GPa下的七个无水实验的结果。淬火运行产物中分析的橄榄石和玻璃成分用于计算每个实验的DMgOl / liq和DNiOl / liq值，进而允许使用Pu等人中校准的Mg和Ni温度计计算温度。（2017）关于文献中的无水1-bar实验。镍温度计恢复了这项研究中所有15个实验的温度，平均偏差为–3°C，其中包括溶解在熔体中的H2O含量最高为4.3 wt％的那些。相比之下，Mg温度计恢复的平均无水1巴实验温度在+14°C以内，但高估了含水实验温度+49至+127°C，平均为+83°C。当Putirka等人的Mg温度计。（2007年）应用，其中包括对运行产品的淬火熔体中分析的H2O（≤4.3wt％）的校正，所有实验温度的平均偏差为（±1σ）+7°C。综合结果表明，DNiOl / liq对熔体中溶解的水（≤4.3wt％H2O）的依赖性可忽略不计，这与DMgOl / liq对熔体中水的强烈依赖性形成鲜明对比。不同于DMgOl /liq⁠，为什么DNiOl / liq对溶解的水不敏感，这是从文献中的光谱学证据得出的，该证据表明Ni2 +（过渡金属）和Mg2 +（碱土金属）具有明显不同的平均配位数（在硅酸盐熔体中分别占主要的四倍和六倍，并且在熔体中存在溶解的水不会影响四重配位的Ni2 +。配位数的不同解释了为什么DNiOl / liq和DMgOl / liq各自对压力，无水熔体成分和熔体水含量具有不同的依赖性。Pu等人的镍温度计的应用。（2017年）从墨西哥弧提取的五个天然样品，文献中报道了橄榄石中的熔体包裹体中H2O含量（3.6-6.7 wt％），其温度与从Putirka等人获得的温度相匹配。（2007）修正所分析H2O含量的Mg温度计。这项研究表明，基于DNiOl / liq的温度计可以应用于地壳深度的含水玄武岩，而无需校正溶解的水含量或压力。