Experimental evidence for melt partitioning between olivine and orthopyroxene in partially molten harzburgite
Miller, Kevin J.
Montesi, Laurent G. J.
Gaetani, Glenn A.
Le Roux, Véronique
MetadataShow full item record
KeywordMelt transport; Rock physics; Fluid-rock interaction; Mid-ocean ridge; Digital rock physics; Partial melt
Observations of dunite channels in ophiolites and uranium series disequilibria in mid-ocean ridge basalt suggest that melt transport in the upper mantle beneath mid-ocean ridges is strongly channelized. We present experimental evidence that spatial variations in mineralogy can also focus melt on the grain scale. This lithologic melt partitioning, which results from differences in the interfacial energies associated with olivine-melt and orthopyroxene-melt boundaries, may complement other melt focusing mechanisms in the upper mantle such as mechanical shear and pyroxene dissolution. We document here lithologic melt partitioning in olivine-/orthopyroxene-basaltic melt samples containing nominal olivine to orthopyroxene ratio of 3 to 2 and melt fractions of 0.02 to 0.20. Experimental samples were imaged using synchrotron-based X-ray microcomputed tomography at a resolution of 700 nm per voxel. By analyzing the local melt fraction distributions associated with olivine and orthopyroxene grains in each sample, we found that the melt partitioning coefficient, i.e., the ratio of melt fraction around olivine to that around orthopyroxene grains, varies between 1.1 and 1.6. The permeability and electrical conductivity of our digital samples were estimated using numerical models and compared to those of samples containing only olivine and basaltic melt. Our results suggest that lithologic melt partitioning and preferential localization of melt around olivine grains might play a role in melt focusing, potentially enhancing average melt ascent velocities.
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 121 (2016): 5776–5793, doi:10.1002/2016JB013122.
Suggested CitationJournal of Geophysical Research: Solid Earth 121 (2016): 5776–5793
Showing items related by title, author, creator and subject.
Ocean climate variability in the eastern North Atlantic during interglacial marine isotope stage 11 : a partial analogue to the Holocene? de Abreu, Lucia; Abrantes, Fatima G.; Shackleton, Nicholas J.; Tzedakis, Polychronis C.; McManus, Jerry F.; Oppo, Delia W.; Hall, Michael A. (American Geophysical Union, 2005-08-30)Similar orbital geometry and greenhouse gas concentrations during marine isotope stage 11 (MIS 11) and the Holocene make stage 11 perhaps the best geological analogue period for the natural development of the present ...
Merging multiple-partial-depth data time series using objective empirical orthogonal function fitting Lin, Ying-Tsong; Newhall, Arthur E.; Duda, Timothy F.; Lermusiaux, Pierre F. J.; Haley, Patrick J. (IEEE, 2010-10-18)In this paper, a method for merging partial overlapping time series of ocean profiles into a single time series of profiles using empirical orthogonal function (EOF) decomposition with the objective analysis is presented. ...
The importance of tidal and lateral asymmetries in stratification to residual circulation in partially mixed estuaries Scully, Malcolm E.; Friedrichs, Carl T. (American Meteorological Society, 2007-06)Measurements collected in the York River estuary, Virginia, demonstrate the important impact that tidal and lateral asymmetries in turbulent mixing have on the tidally averaged residual circulation. A reduction in turbulent ...