Magnetic mineralogy of the Mercurian lithosphere. Issue 11 (11th November 2016)

• Record Type: Journal Article
• Authors: Strauss, B. E.; Feinberg, J. M.; Johnson, C. L.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 11(2016:Nov.)
• Page Start: 2225
• Page End: 2238
• Publication Date: 2016-11-11
• Subjects: Mercury -- magnetism -- rock magnetism -- MESSENGER; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1002/2016JE005054
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: Mercury and Earth are the only inner solar system planets with active, internally generated dynamo magnetic fields. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission recently detected magnetic fields on Mercury that are consistent with lithospheric magnetization. We investigate the physical and chemical environment of Mercury's lithosphere, past and present, to establish the conditions under which magnetization may have been acquired and modified. Three factors are particularly crucial to the determination of crustal composition and iron mineralogy: redox conditions in the planet's crust and mantle, the iron content of the lithosphere, and, for any remanent magnetization, the temperature profile of the lithosphere and its evolution over time. We explore potential mechanisms for remanence acquisition and alteration on Mercury, whose surface environment is both hot and highly reducing. The long‐term thermal history of Mercury's crust plays an important role in the longevity of any remanent crustal magnetization, which may be subject to remagnetization through thermal, viscous, and shock mechanisms. This thermal and compositional framework is used both to constrain plausible candidate minerals that could carry magnetic remanence on Mercury and to evaluate their capacity to acquire and retain sufficient magnetization to be detectable from satellite orbit. We propose that iron metal and its alloys are likely to be the dominant contributors to induced and remanent magnetization in Mercury's lithosphere, with additional contributions from iron silicides, sulfides, and carbides. Key Points: Conditions for magnetization at Mercury are unique among terrestrial planets Temperature, chemistry, and field strength limit possible remanence carriers Further characterization of candidate minerals is needed to understand Mercury's crustal fields