65 research outputs found
Impact of green clay authigenesis on element sequestration in marine settings
Retrograde clay mineral reactions (reverse weathering), including glauconite formation, are
first-order controls on element sequestration in marine sediments. Here, we report sub-
stantial element sequestration by glauconite formation in shallow marine settings from the
Triassic to the Holocene, averaging 3 ± 2 mmol·cm−²·kyr−1 for K, Mg and Al, 16 ± 9 mmol·cm
−²·kyr−1 for Si and 6 ± 3 mmol·cm−²·kyr−1 for Fe, which is ~2 orders of magnitude higher than
estimates for deep-sea settings. Upscaling of glauconite abundances in shallow-water
(0–200 m) environments predicts a present-day global uptake of ~≤ 0.1 Tmol·yr−1 of K, Mg
and Al, and ~0.1–0.4 Tmol·yr−1 of Fe and Si, which is ~half of the estimated Mesozoic
elemental flux. Clay mineral authigenesis had a large impact on the global marine element
cycles throughout Earth’s history, in particular during ‘greenhouse’ periods with sea level
highstand, and is key for better understanding past and present geochemical cycling in
marine sediments
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