The Melting Column as a Filter of Mantle Trace-Element Heterogeneity.
The Melting Column as a Filter of Mantle Trace-Element Heterogeneity.
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熔柱作为地幔微量元素异质性的过滤器。
DOI：
10.1029/2018gc007880
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Bo T
中科院分区：
文献类型：
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作者：
Bo T
在玄武质熔岩和熔融包裹体中观察到的微量元素浓度的变化携带了地幔不均匀性的信息。困难在于解开源异质性的贡献（即，熔融前地幔成分的空间变异性）和过程不均匀性（即，熔体输送的空间和时间变化）。在这里，我们研究了端元假设，即变异性仅由源异质性引起。我们对引入一维稳态熔融柱底部的微量元素变异性的衰减进行建模。我们的研究结果表明，熔融柱可以被认为是一个过滤器，衰减的变异性，根据波长的异质性，微量元素的分配系数，熔体生产率，熔体偏析的效率。我们进一步表明，虽然该模型可以适合的观测，这需要假设不一致的约束岩浆组装的时间尺度。因此，我们推翻了端元假设，相反，我们得出结论，观察到的变异性需要熔体输送的异质性。这可能采取通道或波的形式，并且几乎肯定会与源的异质性相互作用。
The observed variability of trace‐element concentration in basaltic lavas and melt inclusions carries information about heterogeneity in the mantle. The difficulty is to disentangle the contributions of source heterogeneity (i.e., spatial variability of mantle composition before melting) and process heterogeneity (i.e., spatial and temporal variability in melt transport). Here we investigate the end‐member hypothesis that variability arises due to source heterogeneity alone. We model the attenuation of trace‐element variability introduced into the bottom of a one‐dimensional, steady‐state melting column. Our results show that the melting column can be considered to be a filter that attenuates variability according to the wavelength of heterogeneity, the partition coefficient of the trace element, melt productivity, and the efficiency of melt segregation. We further show that while the model can be fit to the observations, this requires assumptions inconsistent with constraints on the timescales of magma assembly. Hence, we falsify the end‐member hypothesis and, instead, conclude that observed variability requires heterogeneity of melt transport. This might take the form of channels or waves and would almost certainly interact with source heterogeneity.