New Constraints on the Lunar Crust and Upper Mantle From Multiple Geophysical Data Sets

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Abstract
Determining the crust–mantle boundary of the Moon has been an important topic in lunar interior studies. However, strong seismic scattering in the lunar subsurface has made it challenging to identify clear crustal reflections or converted seismic phases. In addition, the limited epicentral distances of recorded moonquakes restrict direct constraints on the lunar crust from first‐arriving seismic waves. Consequently, the Moon's crustal structure remains poorly constrained due to the limited availability of seismological evidence. Through joint analysis of seismic, topographic, and gravity data, while accounting for seismic velocity variations predicted by thermal modeling, we obtain new ray tracing results and present new insights on the lunar crust and upper mantle structure. Our results constrain the average global Moho depth to 35.1 2.6 km. Additionally, our results indicate slightly lower seismic velocities in the uppermost mantle than previously estimated, at approximately 7.5 km/s. Introducing the thermal model into the inversion further allows us to constrain the Moon's surface heat flow, with an average value of 10.7 0.8 , which is consistent with the heat flow measurements obtained during the Apollo mission. The refined crustal thickness provides a structural basis for estimating the Moon's bulk Al and Th abundances. The model also better constrains the porosity, density, and radiogenic heat production of the lunar crust, and provide new implications for a pyroxene‐rich upper mantle composition.
Funding Information
  • China Scholarship Council (202104910134)

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