DOI: 10.1016/j.epsl.2018.03.031
Scopus记录号: 2-s2.0-85044438827
论文题名: A hybrid origin of the Martian crustal dichotomy: Degree-1 convection antipodal to a giant impact
作者: Citron R.I. ; Manga M. ; Tan E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 491 起始页码: 58
结束页码: 66
语种: 英语
英文关键词: geodynamics
; mantle convection
; Mars
; planetary evolution
Scopus关键词: Geodynamics
; Tectonics
; Dichotomy boundary
; Geophysical observations
; Magnetic signatures
; Mantle convection
; Mars
; Northern Hemispheres
; Planetary evolutions
; Southern Hemisphere
; Structural geology
; crustal thickness
; geodynamics
; mantle convection
; Mars
; planetary evolution
英文摘要: The Martian crustal dichotomy is the stark ∼5 km difference in surface elevation and ∼26 km difference in crustal thickness between the northern lowlands and southern highlands that originated within 100s of Myr of Mars’ formation. The origin of the dichotomy has broad implications for the geodynamic history of Mars, but purely exogenic or endogenic theories so far cannot explain all of the large scale geophysical observations associated with dichotomy formation. A giant impact can produce the shape and slope of the dichotomy boundary, but struggles to explain Mars’ remanent crustal magnetic signatures and the ultimate formation of Tharsis. Degree-1 mantle convection can relate the crustal dichotomy to the formation of Tharsis, but does not explain the elliptical dichotomy shape and must be initiated by a large pre-existing viscosity jump in the mantle. We propose a hybrid model of dichotomy formation in which a giant impact induces degree-1 convection with an upwelling antipodal to the impact site. In this scenario, a giant impact in the northern hemisphere excavates crust, creating an initial difference in crustal thickness and possibly composition between the two hemispheres. Over 10s to 100s of Myr, the dominant upwelling(s) would migrate to be under the thicker, insulating crust in the southern hemisphere, generating melt that further thickens the southern crust. We examine this process using 3-D mantle convection simulations, and find that a hemispherical difference in crustal thickness and composition caused by a giant impact can induce degree-1 convection with the upwelling(s) antipodal to the impact site in <100 Myr. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109910
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Department of Earth and Planetary Science, University of California Berkeley, Berkeley, CA, United States; Center for Integrative Planetary Science, University of California Berkeley, Berkeley, CA, United States; Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
Recommended Citation:
Citron R.I.,Manga M.,Tan E.. A hybrid origin of the Martian crustal dichotomy: Degree-1 convection antipodal to a giant impact[J]. Earth and Planetary Science Letters,2018-01-01,491