Wehrlites from continental mantle monitor the passage and degassing of carbonated melts
Date
2020
Authors
Aulbach, S.
Lin, A.-B.
Weiss, Y.
Yaxley, Gregory
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Publisher
European Association of Geochemistry
Abstract
Continental rifting has been linked to the thinning and destruction of cratonic lithosphere and to the release of enough CO2 to impact the global climate. This fundamental plate tectonic process facilitates the infiltration and mobilisation of smallvolume carbonated melts, which may interact with mantle peridotite to form wehrlite through the reaction: enstatite thorn dolomite (melt) = forsterite thorn diopside thorn CO2 (vapour). Application to mantle xenolith suites from various rifts and basins shows that 2.9 to 10.2 kg CO2 are released per 100 kg of wehrlite formed. For the Eastern Rift (Africa), this results in estimated CO2 fluxes of 6.5 +/- 4.1 Mt yr(-1), similar to estimates of mantle contributions based on surficial CO2 surveys. Thus, wehrlite-bearing xenolith suites can be used to monitor present and past CO2 mobility through the continental lithosphere, ultimately with diffuse degassing to the atmosphere. They may also reveal the CO2 flux in lithospheric provinces where carbonated melts or continent-scale rifts are not observed at the surface.
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Keywords
continental rifts, carbonated melts, extension, metasomatism, CO2 flux, tectonic degassing
Citation
Aulbach, S., Lin, A.-B., Weiss, Y., Yaxley, G.M. (2020) Wehrlites from continental mantle monitor the passage and degassing of carbonated melts. Geochem. Persp. Let. 15, 30–34.
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Geochemical Perspectives Letters
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Journal article
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Open Access
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Creative Commons License CC BY-NC-ND 4.0
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