DOI: 10.1016/j.epsl.2017.12.028
Scopus记录号: 2-s2.0-85040546955
论文题名: Constraints on dynamic topography from asymmetric subsidence of the mid-ocean ridges
作者: Watkins C.E. ; Conrad C.P.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 484 起始页码: 264
结束页码: 275
语种: 英语
英文关键词: bathymetry
; dynamic topography
; mantle flow
; mid-ocean ridges
; seafloor subsidence
Scopus关键词: Bathymetry
; Sea level
; Structural geology
; Submarine geology
; Subsidence
; Tectonics
; Direct observations
; Dynamic subsidences
; Dynamic topography
; Mantle flow
; Mid-ocean ridges
; Sea floor
; Seafloor bathymetry
; Viscosity variations
; Topography
; bathymetry
; mantle structure
; mid-ocean ridge
; seafloor
; subsidence
; topography
; viscosity
; Atlantic Ocean
; East Pacific Rise
; Mid-Atlantic Ridge
; Pacific Ocean
英文摘要: Stresses from mantle convection deflect Earth's surface vertically, producing dynamic topography that is important for continental dynamics and sea-level change but difficult to observe due to overprinting by isostatic topography. For long wavelengths (∼104 km), the amplitude of dynamic topography is particularly uncertain, with mantle flow models typically suggesting larger amplitudes (>1000 m) than direct observations. Here we develop a new constraint on the amplitude of long-wavelength dynamic topography by examining asymmetries in seafloor bathymetry across mid-ocean ridges. We compare bathymetric profiles across the Mid-Atlantic Ridge (MAR) and the East Pacific Rise (EPR) and we find that the South American flank of both ridges subsides faster than its opposing flank. This pattern is consistent with dynamic subsidence across South America, supported by downwelling in the lower mantle. To constrain the amplitude of dynamic topography, we compare bathymetric profiles across both ridges after correcting bathymetry for several different models of dynamic topography with varying amplitudes and spatial patterns. We find that long-wavelength dynamic topography with an amplitude of only ∼500 m explains the observed asymmetry of the MAR. A similar model can explain EPR asymmetry but is complicated by additional asymmetrical topography associated with tectonic, crustal thickness, and/or asthenospheric temperature asymmetries across the EPR. After removing 500 m of dynamic topography, both the MAR and EPR exhibit a slower seafloor subsidence rate (∼280–290 m/Myr1/2) than previously reported. Our finding of only ∼500 m of long-wavelength dynamic topography may indicate the importance of thermochemical convection and/or large viscosity variations for lower mantle dynamics. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110064
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 Sciences, Rutgers University, Piscataway, NJ, United States; Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Oslo, Norway; Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI, United States
Recommended Citation:
Watkins C.E.,Conrad C.P.. Constraints on dynamic topography from asymmetric subsidence of the mid-ocean ridges[J]. Earth and Planetary Science Letters,2018-01-01,484