@article{175bb30d2f484ecb9bee19d60db68d9d,
title = "Constraints on the Depth, Thickness, and Strength of the G Discontinuity in the Central Pacific From S Receiver Functions",
abstract = "The relative motion of the lithosphere with respect to the asthenosphere implies the existence of a boundary zone that accommodates shear between the rigid plates and flowing mantle. This shear zone is typically referred to as the lithosphere-asthenosphere boundary (LAB). The width of this zone and the mechanisms accommodating shear across it have important implications for coupling between mantle convection and surface plate motion. Seismic observations have provided evidence for several physical mechanisms that might help enable relative plate motion, but how these mechanisms each contribute to the overall accommodation of shear remains unclear. Here we present receiver function constraints on the discontinuity structure of the oceanic upper mantle at the NoMelt site in the central Pacific, where local constraints on shear velocity, anisotropy, conductivity, and attenuation down to ∼300 km depth provide a comprehensive picture of upper mantle structure. We image a seismic discontinuity with a Vsv decrease of 4.5% or more over a 0–20 km thick gradient layer centered at a depth of ∼65 km. We associate this feature with the Gutenberg discontinuity (G), and interpret our observation of G as resulting from strain localization across a dehydration boundary based on the good agreement between the discontinuity depth and that of the dry solidus. Transitions in Vsv, azimuthal anisotropy, conductivity, and attenuation observed at roughly similar depths suggest that the G discontinuity represents a region of localized strain within a broader zone accommodating shear between the lithosphere and asthenosphere.",
author = "Mark, {H. F.} and Collins, {J. A.} and D. Lizarralde and G. Hirth and Gaherty, {J. B.} and Evans, {R. L.} and Behn, {M. D.}",
note = "Funding Information: The authors thank the Captains and crews of the R/V Marcus G. Langseth and the R/V Melville, and the OBS engineers and technicians from the Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution. The professionalism and expertise of these individuals were key to the success of the NoMelt experiment. The authors also thank Emily Hopper for her helpful advice on receiver functions. Three anonymous reviewers provided helpful comments and suggestions that greatly improved this manuscript. The data used in this research were recorded by instruments from the Ocean Bottom Seismograph Instrument Pool ( www.obsip.org ), which is funded by the National Science Foundation. This work was supported by NSF grant OCE‐0928663 to D. Lizarralde, J. Collins, and R. Evans, NSF grant OCE‐0927172 to G. Hirth, NSF grant OCE‐0928270 to J. Gaherty, NSF grant EAR‐1624109 to M. Behn, and an NSF Graduate Research Fellowship to H. Mark. Funding Information: The authors thank the Captains and crews of the R/V Marcus G. Langseth and the R/V Melville, and the OBS engineers and technicians from the Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution. The professionalism and expertise of these individuals were key to the success of the NoMelt experiment. The authors also thank Emily Hopper for her helpful advice on receiver functions. Three anonymous reviewers provided helpful comments and suggestions that greatly improved this manuscript. The data used in this research were recorded by instruments from the Ocean Bottom Seismograph Instrument Pool (www.obsip.org), which is funded by the National Science Foundation. This work was supported by NSF grant OCE-0928663 to D. Lizarralde, J. Collins, and R. Evans, NSF grant OCE-0927172 to G. Hirth, NSF grant OCE-0928270 to J. Gaherty, NSF grant EAR-1624109 to M. Behn, and an NSF Graduate Research Fellowship to H. Mark. Publisher Copyright: {\textcopyright} 2021. American Geophysical Union. All Rights Reserved.",
year = "2021",
month = apr,
doi = "10.1029/2019JB019256",
language = "English (US)",
volume = "126",
journal = "Journal of Geophysical Research: Solid Earth",
issn = "2169-9313",
publisher = "Wiley-Blackwell",
number = "4",
}