The Melting Column as a Filter of Mantle Trace-Element Heterogeneity

Bo, Tong and Katz, Richard F. and Shorttle, Oliver and Rudge, John F. (2018) The Melting Column as a Filter of Mantle Trace-Element Heterogeneity. Geochemistry, Geophysics, Geosystems, 19 (12). pp. 4694-4721. ISSN 15252027 DOI https://doi.org/10.1029/2018GC007880

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Abstract

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.

Item Type:	Article
Uncontrolled Keywords:	2028AREP; IA74
Subjects:	02 - Geodynamics, Geophysics and Tectonics
Divisions:	02 - Geodynamics, Geophysics and Tectonics 08 - Green Open Access
Journal or Publication Title:	Geochemistry, Geophysics, Geosystems
Volume:	19
Page Range:	pp. 4694-4721
Identification Number:	https://doi.org/10.1029/2018GC007880
Depositing User:	Sarah Humbert
Date Deposited:	12 Apr 2019 09:30
Last Modified:	12 Apr 2019 09:30
URI:	http://eprints.esc.cam.ac.uk/id/eprint/4470

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