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Could Giant Basin-Forming Impacts Have Killed Martian Dynamo?The observed strong remanent crustal magnetization at the surface of Mars suggests an active dynamo in the past and ceased to exist around early to middle Noachian era, estimated by examining remagnetization strengths in extant and buried impact basins. We investigate whether the Martian dynamo could have been killed by these large basin-forming impacts, via numerical simulation of subcritical dynamos with impact-induced thermal heterogeneity across the core-mantle boundary. We find that subcritical dynamos are prone to the impacts centered on locations within 30 deg of the equator but can easily survive those at higher latitudes. Our results further suggest that magnetic timing places a strong constraint on postimpact polar reorientation, e.g., a minimum 16 deg polar reorientation is needed if Utopia is the dynamo killer.
Document ID
20160005758
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kuang, W.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Jiang, W.
(Science Systems and Applications, Inc. Lanham, MD, United States)
Roberts, J.
(Johns Hopkins Univ. Laurel, MD, United States)
Frey, H. V.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
May 3, 2016
Publication Date
November 22, 2014
Publication Information
Publication: Geophysical Research Letters
Publisher: AGU Publications
Volume: 41
Issue: 22
ISSN: 0094-8276
Subject Category
Geosciences (General)
Report/Patent Number
GSFC-E-DAA-TN31859
Funding Number(s)
CONTRACT_GRANT: NNG12HP06C
Distribution Limits
Public
Copyright
Other
Keywords
Martian Dynamo
Paleopolar reorientation
Magnetic Fields

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