The effect of liquid composition on the partitioning of Ni between olivine and silicate melt.
The effect of liquid composition on the partitioning of Ni between olivine and silicate melt.
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DOI：
10.1007/s00410-016-1319-8
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Stolper EM
中科院分区：
文献类型：
--
作者：
Matzen AK;Baker MB;Beckett JR;Wood BJ;Stolper EM
我们报道了旨在分离温度和压力与液体组成对镍在橄榄石和液体之间分配的影响的实验结果。实验在1300至1600℃和1℃至3.0 Gpa的条件下进行，使用高压石墨-铂双胶囊中的大洋中脊玄武岩(MORB)玻璃和一个大气压下由圣卡洛斯橄榄石单晶制成的坩埚中的粉末MORB。在这些实验中，通过改变压力和温度，我们产生了一系列液体，每种液体的组成大约是恒定的(~12、~15和~21wt%的氧化镁)。之前，我们使用了类似的方法来证明，对于~18wt%的液体，氧化镁是温度的强烈函数。结合这里给出的新数据和我们以前的结果，我们可以将温度的影响与组成分开。我们基于Ni-Mg交换反应对我们的数据进行了拟合，该反应产生了每个恒定组成的子集实验显示了与先前报道的含有~18wt%MgO的液体大致相同的温度依赖关系。将这里提供的新数据(15个实验)与我们之前发表的13个实验(硅酸盐液体中含有~18wt%氧化镁的实验)与上述表达式进行拟合，得到−=1.597±0.229。将文献中的数据相加，得到−=2.075×106(K)和×4505×10196(K)，这是一组系数，得出了适用于广泛熔体组成的预测方程。我们利用我们的工作结果模拟了不同厚度的岩石圈下橄榄岩的熔融过程，结果表明：(1)镁橄榄石斑晶中的NiO与岩石圈厚度之间存在正相关，且存在温度依赖性；(2)天然样品的斜率大小与我们实验确定的温度依赖性一致。产生镁橄榄石中NiO与岩石圈厚度正相关的替代过程是可能的，例如熔融不含橄榄石的辉石岩，但它们不需要解释观察到的初始结晶橄榄石中NiO浓度与岩石圈厚度的相关性。本文的在线版本(doi：10.1007/s00410-016-1319-8)包含补充材料，授权用户可以使用。
We report the results of experiments designed to separate the effects of temperature and pressure from liquid composition on the partitioning of Ni between olivine and liquid, . Experiments were performed from 1300 to 1600 °C and 1 atm to 3.0 GPa, using mid-ocean ridge basalt (MORB) glass surrounded by powdered olivine in graphite–Pt double capsules at high pressure and powdered MORB in crucibles fabricated from single crystals of San Carlos olivine at one atmosphere. In these experiments, pressure and temperature were varied in such a way that we produced a series of liquids, each with an approximately constant composition (~12, ~15, and ~21 wt% MgO). Previously, we used a similar approach to show that for a liquid with ~18 wt% MgO is a strong function of temperature. Combining the new data presented here with our previous results allows us to separate the effects of temperature from composition. We fit our data based on a Ni–Mg exchange reaction, which yields Each subset of constant composition experiments displays roughly the same temperature dependence of (i.e.,) as previously reported for liquids with ~18 wt% MgO. Fitting new data presented here (15 experiments) in conjunction with our 13 previously published experiments (those with ~18 wt% MgO in the silicate liquid) to the above expression gives = 3641 ± 396 (K) and = − 1.597 ± 0.229. Adding data from the literature yields = 4505 ± 196 (K) and = − 2.075 ± 0.120, a set of coefficients that leads to a predictive equation for applicable to a wide range of melt compositions. We use the results of our work to model the melting of peridotite beneath lithosphere of varying thickness and show that: (1) a positive correlation between NiO in magnesian olivine phenocrysts and lithospheric thickness is expected given a temperature-dependent and (2) the magnitude of the slope for natural samples is consistent with our experimentally determined temperature dependence. Alternative processes to generate the positive correlation between NiO in magnesian olivines and lithospheric thickness, such as the melting of olivine-free pyroxenite, are possible, but they are not required to explain the observed correlation of NiO concentration in initially crystallizing olivine with lithospheric thickness. The online version of this article (doi:10.1007/s00410-016-1319-8) contains supplementary material, which is available to authorized users.
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影响因子：
64.8
作者：
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