Reconciling extensive mantle hydration at subduction trenches and limited deep H2O fluxes
Authors: Arcay Diane , Cerpa Nestor , Padrón-Navarta José Alberto 
Published: March 2022

&lt;p&gt;&lt;span&gt;The long-term global sea level depends on the balance of H&lt;sub&gt;2&lt;/sub&gt;O exchanges between the Earth's mantle and the surface through both volcanism (mantle degassing) and subduction of hydrous minerals (mantle regassing). The estimates of H&lt;sub&gt;2&lt;/sub&gt;O fluxes by the current thermopetrological subduction models predict that regassing exceeds degassing by 60%, which may lead to a sea-level drop of at least a hundred meters in the last 540 Ma [Parai &amp; Mukhopadhyay, 2012, Earth Planet. Sc. Lett., 317, 396-406. https://doi.org/10.1016/j.epsl.2011.11.024. These models further imply a moderate (&lt;/span&gt;&lt;span&gt;&lt;img src=&quot;data:image/jpeg;base64,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&quot; width=&quot;56&quot; height=&quot;17&quot; /&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;Tg/Myr) global input of H&lt;sub&gt;2&lt;/sub&gt;O at the subduction trenches. In contrast, geological constraints suggest a near-steady state of long-term sea level while geophysical observations advocate for a larger global H&lt;sub&gt;2&lt;/sub&gt;O input, especially given the large amounts of hydrated lithospheric mantle that are inferred at present-day subduction trenches. To address this paradox, we revise the subduction-H&lt;sub&gt;2&lt;/sub&gt;O flux calculations using recently published experimental data on natural hydrated peridotites at high-pressure conditions, which suggest that all hydrated phases destabilize below 800&amp;#730;C for pressures higher than 8 GPa [Maurice et al., 2018, Contrib. Mineral. Petrol, 173(10), 86. https://doi.org/10.1007/s00410-018-1507-9 ]. Our reassessed thermopetrological models show that a prominent global H&lt;sub&gt;2&lt;/sub&gt;O input (&lt;/span&gt;&lt;span&gt;&lt;img src=&quot;data:image/jpeg;base64,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&quot; width=&quot;72&quot; height=&quot;18&quot; /&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;Tg/Myr), mainly conveyed by the layer of subducted serpentinized mantle, is compatible with a limited global H&lt;sub&gt;2&lt;/sub&gt;O retention in subducted slabs at mid-upper mantle depths (&lt;/span&gt;&lt;span&gt;&lt;img src=&quot;data:image/jpeg;base64,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&quot; width=&quot;74&quot; height=&quot;18&quot; /&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;Tg/Myr), including in models that consider some worldwide variability of the input serpentine. We also show that the global H&lt;sub&gt;2&lt;/sub&gt;O retention at mid-upper mantle depths is only driven by the hydrated mantle of coldest subducting plates. Overall, our models show that the present-day global water retention in subducting plates beyond mid-upper mantle depths barely exceeds the estimations of mantle degassing, and thus quantitatively support the stable-sea level scenario over geological times.&lt;/span&gt;&lt;/p&gt;