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Variations in mid-ocean ridge CO2 emissions driven by glacial cycles.

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Title: Variations in mid-ocean ridge CO2 emissions driven by glacial cycles.
Authors: Burley, Jonathan M.A.1 jonathan.burley@earth.ox.ac.uk, Katz, Richard F.1
Source: Earth & Planetary Science Letters. Sep2015, Vol. 426, p246-258. 13p.
Subjects: Mid-ocean ridges, Carbon dioxide, Glaciation, Earth's mantle, Geochemistry, Volcanism
Abstract: The geological record documents links between glacial cycles and volcanic productivity, both subaerially and, tentatively, at mid-ocean ridges. Sea-level-driven pressure changes could also affect chemical properties of mid-ocean ridge volcanism. We consider how changing sea-level could alter the CO 2 emissions rate from mid-ocean ridges on both the segment and global scale. We develop a simplified transport model for a highly incompatible trace element moving through a homogeneous mantle; variations in the concentration and the emission rate of the element are the result of changes in the depth of first silicate melting. The model predicts an average global mid-ocean ridge CO 2 emissions rate of 53 Mt/yr or 91 Mt/yr for an average source mantle CO 2 concentration of 125 or 215 ppm by weight, in line with other estimates. We show that falling sea level would cause an increase in ridge CO 2 emissions about 100 kyrs after the causative sea level change. The lag and amplitude of the response are sensitive to mantle permeability and plate spreading rate. For a reconstructed sea-level time series of the past million years, we predict variations of up to 12 % in global mid-ocean ridge CO 2 emissions. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:The geological record documents links between glacial cycles and volcanic productivity, both subaerially and, tentatively, at mid-ocean ridges. Sea-level-driven pressure changes could also affect chemical properties of mid-ocean ridge volcanism. We consider how changing sea-level could alter the CO 2 emissions rate from mid-ocean ridges on both the segment and global scale. We develop a simplified transport model for a highly incompatible trace element moving through a homogeneous mantle; variations in the concentration and the emission rate of the element are the result of changes in the depth of first silicate melting. The model predicts an average global mid-ocean ridge CO 2 emissions rate of 53 Mt/yr or 91 Mt/yr for an average source mantle CO 2 concentration of 125 or 215 ppm by weight, in line with other estimates. We show that falling sea level would cause an increase in ridge CO 2 emissions about 100 kyrs after the causative sea level change. The lag and amplitude of the response are sensitive to mantle permeability and plate spreading rate. For a reconstructed sea-level time series of the past million years, we predict variations of up to 12 % in global mid-ocean ridge CO 2 emissions. [ABSTRACT FROM AUTHOR]
ISSN:0012821X
DOI:10.1016/j.epsl.2015.06.031