Timing of the martian dynamo: New constraints for a core field 4.5 and 3.7 Ga ago.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32494687.
- Also identified by DOI 10.1126/sciadv.aba0513 and PMC identifier 7195189.
- Licence recorded as CC BY-NC.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
The absence of crustal magnetic fields above the martian basins Hellas, Argyre, and Isidis is often interpreted as proof of an early, before 4.1 billion years (Ga) ago, or late, after 3.9 Ga ago, dynamo. We revisit these interpretations using new MAVEN magnetic field data. Weak fields are present over the 4.5-Ga old Borealis basin, with the transition to strong fields correlated with the basin edge. Magnetic fields, confined to a near-surface layer, are also detected above the 3.7-Ga old Lucus Planum. We conclude that a dynamo was present both before and after the formation of the basins Hellas, Utopia, Argyre, and Isidis. A long-lived, Earth-like dynamo is consistent with the absence of magnetization within large basins if the impacts excavated large portions of strongly magnetic crust and exposed deeper material with lower concentrations of magnetic minerals.