Seismic evidence for a highly heterogeneous martian mantle.
basic_science · Level V
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- Record sourced from PubMed, PMID 40875851.
- Also identified by DOI 10.1126/science.adk4292.
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Abstract
A planet's interior is a time capsule, preserving clues to its early history. We report the discovery of kilometer-scale heterogeneities throughout Mars' mantle, detected seismically through pronounced wavefront distortion of energy arriving from deeply probing marsquakes. These heterogeneities, likely remnants of the planet's formation, imply a mantle that has undergone limited mixing driven by sluggish convection. Their size and survival constrain Mars' poorly known mantle rheology, indicating a high viscosity of 10<sup>21.3</sup> to 10<sup>21.9</sup> pascal-seconds and low temperature dependence, with an effective activation energy of 70 to 90 kilojoules per mole, suggesting a mantle deforming by dislocation creep. The limited mixing, coupled with ubiquitous, scale-invariant heterogeneities, reflects a highly disordered mantle, characteristic of the more primitive interior evolution of a single-plate planet, contrasting sharply with the tectonically active Earth.