Yu, ChunquanDay, Elizabeth A.de Hoop, Maarten V.Campillo, MichelGoes, SaskiaBlythe, Rachel A.van der Hilst, Robert D.2018-07-162018-07-162018Yu, Chunquan, Day, Elizabeth A., de Hoop, Maarten V., et al.. "Compositional heterogeneity near the base of the mantle transition zone beneath Hawaii." <i>Nature Communications,</i> 9, (2018) Springer Nature: https://doi.org/10.1038/s41467-018-03654-6.https://hdl.handle.net/1911/102447Global seismic discontinuities near 410 and 660 km depth in Earth’s mantle are expressions of solid-state phase transitions. These transitions modulate thermal and material fluxes across the mantle and variations in their depth are often attributed to temperature anomalies. Here we use novel seismic array analysis of SSwaves reflecting off the 410 and 660 below the Hawaiian hotspot. We find amplitude–distance trends in reflectivity that imply lateral variations in wavespeed and density contrasts across 660 for which thermodynamic modeling precludes a thermal origin. No such variations are found along the 410. The inferred 660 contrasts can be explained by mantle composition varying from average (pyrolitic) mantle beneath Hawaii to a mixture with more melt-depleted harzburgite southeast of the hotspot. Such compositional segregation was predicted, from petrological and numerical convection studies, to occur near hot deep mantle upwellings like the one often invoked to cause volcanic activity on Hawaii.engThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. Journal articlehttps://doi.org/10.1038/s41467-018-03654-6