A Magnetotelluric Study of Mantle Heterogeneities Beneath the Northeastern United States
Name
Geochem Geophys Geosyst - 2025 - Kim - A Magnetotelluric Study of Mantle Heterogeneities Beneath the Northeastern United.pdf
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3.18 MB
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9325eaf7f7343c273c8757ff5903ca8a
Author(s)
Kim, Jae Deok
Evans, Rob. L.
Date Issued
October 25, 2025
Journal
Geochemistry, Geophysics, Geosystems
Publisher
Wiley
Citation
Kim, J. D., & Evans, R. L. (2025). A magnetotelluric study of mantle heterogeneities beneath the Northeastern United States. Geochemistry, Geophysics, Geosystems, 26, e2025GC012586.
Version
Final published version
Abstract
Analysis of magnetotelluric (MT) data across the northern Appalachian region reveals significantmantle heterogeneity. By inverting a subset of long‐period EarthScope USArray MT data, we constructed athree‐dimensional electrical resistivity model that provides new insights into the seismic low‐velocity NorthernAppalachian Anomaly (NAA). Comparison with empirical conductivity models indicates that the low‐resistivity anomalies along the northern and western edges of the NAA cannot be explained by temperaturealone and likely require the presence of volatiles, such as CO2‐rich or hydrous melts, or other volatile‐bearingphases, to reduce mantle resistivity to the observed levels. In addition, our modeling suggests that certainalternative lithologies, particularly hydrous clinopyroxenites, may also contribute to the observed conductivity,implying that compositional heterogeneity plays a role alongside fluids or melt. These conductive features mayreflect partial melting or metasomatic enrichment of carbonated and hydrated mantle domains introduced duringpast subduction or plume interactions, potentially mobilized by edge‐driven convection at lithosphericboundaries. We also resolve a deep resistive feature in western New England, interpreted as a dry and depletedlithospheric block, though its nature remains uncertain due to limited seismic expression and the relatively lowsensitivity of MT to resistive structures. Our results suggest that the upper mantle beneath New England is bothcompositionally and thermally heterogeneous, shaped by a complex tectonic history involving subduction,metasomatism, lithospheric thinning, and ongoing asthenospheric processes.
MIT Department
Joint Program in Oceanography/Applied Ocean Science and Engineering
Woods Hole Oceanographic Institution
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DOI of Published Version
https://doi.org/10.1029/2025GC012586
