Fast magma ascent, revised estimates from the deglaciation of Iceland

Rees Jones, David W. and Rudge, John F. (2020) Fast magma ascent, revised estimates from the deglaciation of Iceland. Earth and Planetary Science Letters, 542. p. 116324. ISSN 0012821X DOI

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Partial melting of asthenospheric mantle generates magma that supplies volcanic systems. The timescale of melt extraction from the mantle has been hotly debated. Microstructural measurements of permeability typically suggest relatively slow melt extraction (1 m/yr) whereas geochemical (Uranium-decay series) and geophysical observations suggest much faster melt extraction (100 m/yr). The deglaciation of Iceland triggered additional mantle melting and magma flux at the surface. The rapid response has been used to argue for relatively rapid melt extraction. However, this episode must, at least to some extent, be unrepresentative, because the rates of magma eruption at the surface increased about thirty-fold relative to the steady state. Our goal is to quantify this unrepresentativeness. We develop a one-dimensional, time-dependent and nonlinear (far from steady-state), model forced by the most recent, and best mapped, Icelandic deglaciation. We find that 30 m/yr is the best estimate of the steady-state maximum melt velocity. This is a factor of about 3 smaller than previously claimed, but still relatively fast. We translate these estimates to other mid-ocean ridges accounting for differences in passive and active upwelling and degree of melting. We find that fast melt extraction greater than about 10 m/yr prevails globally.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
08 - Green Open Access
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 542
Page Range: p. 116324
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 23 Oct 2020 18:22
Last Modified: 19 May 2021 00:01

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