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Creators/Authors contains: "Feinberg, J M"

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  1. null (Ed.)
    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. 
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  2. Archaeomagnetic dating is a firmly established dating technique applicable to a wide variety of heat-treated anthropological materials and is advantageous for sites that lack materials suitable for radiocarbon dating. To correct recent misinterpretations of the method, we provide examples of how archaeomagnetic dating curves are calibrated and show how, in some instances, the technique can provide superior results. We emphasize that no single dating technique is capable of resolving the challenging chronology controversies in the Levant, and instead argue that multiple dating methods must be integrated in order to achieve the highest possible temporal resolution. 
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