气候变化领域集成服务门户(CCPortal): Quantifying the Relationship Between Short-Wavelength Dynamic Topography and Thermomechanical Structure of the Upper Mantle Using Calibrated Parameterization of Anelasticity

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DOI	10.1029/2019JB019062
	Quantifying the Relationship Between Short-Wavelength Dynamic Topography and Thermomechanical Structure of the Upper Mantle Using Calibrated Parameterization of Anelasticity
	Richards F.D.; Hoggard M.J.; White N.; Ghelichkhan S.
发表日期	2020
ISSN	21699313
卷号	125 期号:9
英文摘要	Oceanic residual depth varies on (Formula presented.) 5,000 km wavelengths with amplitudes of ±1 km. A component of this short-wavelength signal is dynamic topography caused by convective flow in the upper ∼300 km of the mantle. It exerts a significant influence on landscape evolution and sea level change, but its contribution is often excluded in geodynamic models of whole-mantle flow. Using seismic tomography to resolve buoyancy anomalies in the oceanic upper mantle is complicated by the dominant influence of lithospheric cooling on velocity structure. Here, we remove this cooling signal from global surface wave tomographic models, revealing a correlation between positive residual depth and slow residual velocity anomalies at depths <300 km. To investigate whether these anomalies are of sufficient amplitude to account for short-wavelength residual depth variations, we calibrate an experimentally derived parameterization of anelastic deformation at seismic frequencies to convert shear wave velocity into temperature, density, and diffusion creep viscosity. Asthenospheric temperature anomalies reach +150°C in the vicinity of major magmatic hot spots and correlate with geochemical and geophysical proxies for potential temperature along mid-ocean ridges. Locally, we find evidence for a ∼150 km-thick, low-viscosity asthenospheric channel. Incorporating our revised density structure into models of whole-mantle flow yields reasonable agreement with residual depth observations and suggests that ±30 km deviations in local lithospheric thickness account for a quarter of total amplitudes. These predictions remain compatible with geoid constraints and substantially improve the fit between power spectra of observed and predicted dynamic topography. This improvement should enable more accurate reconstruction of the spatiotemporal evolution of Cenozoic dynamic topography. ©2020. The Authors.
英文关键词	anelasticity; dynamic topography; Earth rheology; lithosphere-asthenosphere system; mantle dynamics; mantle thermomechanical structure
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187605
作者单位	Department of Earth Science and Engineering, Imperial College London, London, United Kingdom; Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, United States; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States; Bullard Laboratories, Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom; Research School of Earth Sciences, Australian National University, Acton, ACT, Australia
推荐引用方式 GB/T 7714	Richards F.D.,Hoggard M.J.,White N.,et al. Quantifying the Relationship Between Short-Wavelength Dynamic Topography and Thermomechanical Structure of the Upper Mantle Using Calibrated Parameterization of Anelasticity[J],2020,125(9).
APA	Richards F.D.,Hoggard M.J.,White N.,&Ghelichkhan S..(2020).Quantifying the Relationship Between Short-Wavelength Dynamic Topography and Thermomechanical Structure of the Upper Mantle Using Calibrated Parameterization of Anelasticity.Journal of Geophysical Research: Solid Earth,125(9).
MLA	Richards F.D.,et al."Quantifying the Relationship Between Short-Wavelength Dynamic Topography and Thermomechanical Structure of the Upper Mantle Using Calibrated Parameterization of Anelasticity".Journal of Geophysical Research: Solid Earth 125.9(2020).