Magnetic anomalies in the Imbrium and Schrödinger impact basins: Orbital evidence for persistence of the lunar core dynamo into the Imbrian epoch
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Magnetic anomalies in the Imbrium and Schrödinger impact basins: Orbital evidence for persistence of the lunar core dynamo into the Imbrian epoch 2016, 121 (11):2268 Journal of Geophysical Research: PlanetsRights
© 2016. American Geophysical Union. All Rights Reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Approximate maps of the lunar crustal magnetic field at low altitudes in the vicinities of the three Imbrian-aged impact basins, Orientale, Schrdinger, and Imbrium, have been constructed using Lunar Prospector and Kaguya orbital magnetometer data. Detectable anomalies are confirmed to be present well within the rims of Imbrium and Schrdinger. Anomalies in Schrdinger are asymmetrically distributed about the basin center, while a single isolated anomaly is most clearly detected within Imbrium northwest of Timocharis crater. The subsurface within these basins was heated to high temperatures at the time of impact and required long time periods (up to 1 Myr) to cool below the Curie temperature for metallic iron remanence carriers (1043 K). Therefore, consistent with laboratory analyses of returned samples, a steady, long-lived magnetizing field, i.e., a former core dynamo, is inferred to have existed when these basins formed. The asymmetrical distribution within Schrdinger suggests partial demagnetization by later volcanic activity when the dynamo field was much weaker or nonexistent. However, it remains true that anomalies within Imbrian-aged basins are much weaker than those within most Nectarian-aged basins. The virtual absence of anomalies within Orientale where impact melt rocks (the Maunder Formation) are exposed at the surface is difficult to explain unless the dynamo field was much weaker during the Imbrian period.Note
6 month embargo; First published: 15 November 2016ISSN
21699097Version
Final published versionAdditional Links
http://doi.wiley.com/10.1002/2016JE005166ae974a485f413a2113503eed53cd6c53
10.1002/2016JE005166