Reverse weathering in marine sediments and the geochemical cycle of potassium in seawater: Insights from the K isotopic composition (41K/39K) of deep-sea pore-fluids

Ramos, D. P. Santiago; Morgan, Leah E.; Lloyd, Nicholas S.; Higgins, John A.

doi:10.1016/j.gca.2018.02.035

Cited by 77 publications

(38 citation statements)

References 69 publications

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“…Our results indicate that there are natural variations in the 41 2) The δ 41 K value of seawater is ~0.6‰ enriched in K compared to bulk silicate Earth, again in agreement with Wang and Jacobsen 2 . This offset could be a result of K isotope fractionation during secondary clay formation associated with (a) continental silicate weathering, (b) alteration of oceanic crust, and/or (c) diagenesis of marine sediments 31,32 .…”

Section: Discussionmentioning

confidence: 99%

“…Given that the K isotope composition of K-rich minerals shows a range of >1‰, the δ K composition of mineral-sourced potassium available to plants is potentially variable though it is generally expected to have a δ 41 K value close to bulk silicate Earth (-0.54‰). A complicating factor in determining the δ 41 K of this K source is that weathering can be accompanied by secondary clay formation, which has been suggested to fractionate K isotopes in marine sediments 31,32 . In contrast, the bioavailable K in cultures treated with fertilizers is likely homogenous (e.g.…”

Section: Sources Of Potassium Isotope Variability In Biological Systemsmentioning

confidence: 99%

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High-precision ⁴¹K/³⁹K measurements by MC-ICP-MS indicate terrestrial variability of δ⁴¹K

Morgan

Ramos

Davidheiser‐Kroll

et al. 2018

J. Anal. At. Spectrom.

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116

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Section: Discussionmentioning

confidence: 99%

Section: Sources Of Potassium Isotope Variability In Biological Systemsmentioning

confidence: 99%

High-precision ⁴¹K/³⁹K measurements by MC-ICP-MS indicate terrestrial variability of δ⁴¹K

Morgan

Ramos

Davidheiser‐Kroll

et al. 2018

J. Anal. At. Spectrom.

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116

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“…This large depletion in 41 K is hard to explain by any known processes. The largest variation of K isotopes seen among terrestrial natural samples is only ~1‰, and this is due to low-temperature processes such as hydrothermal alteration and clay formation (Parendo et al, 2017;Morgan et al, 2018;Santiago Ramos et al, 2018). Such a large K isotopic fractionations has not yet been observed among carbonaceous and ordinary chondrites or differentiated lunar, martian and eucrite meteorites (Bloom et al, 2018;Tian et al, 2018;Ku and Jacobsen, 2019).…”

Section: The Origin Of the K Isotopic Fractionation In Aubritesmentioning

confidence: 99%

Potassium isotopic compositions of enstatite meteorites

Zhao

Lodders

Bloom

et al. 2019

Meteorit & Planetary Scien

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Enstatite chondrites and aubrites are meteorites that show the closest similarities to the Earth in many isotope systems that undergo mass-independent and mass-dependent isotopic fractionations. Due to the analytical challenges to obtain high-precision K isotopic compositions in the past, potential differences in K isotopic compositions between enstatite meteorites and the Earth remained uncertain. We report the first high-precision K isotopic compositions of eight enstatite chondrites and four aubrites and find that there is a significant variation of K isotopic compositions among enstatite meteorites (from −2.34‰ to −0.18‰). However, K isotopic compositions of nearly all enstatite meteorites scatter around the Bulk Silicate Earth (BSE) value. The average K isotopic composition of the eight enstatite chondrites (−0.47 ±0.57‰) is indistinguishable from the BSE value (−0.48 ±0.03‰), thus further corroborating the isotopic similarity between Earth' building blocks and enstatite meteorite precursors. We found no correlation of K isotopic compositions with the chemical groups, petrological types, shock degrees, and terrestrial weathering conditions; however, the variation of K isotopes among enstatite meteorite can be attributed to the parent-body processing. Our sample of the main-group aubrite MIL 13004 is exceptional and has an extremely light K isotopic composition (δ 41 K=−2.34 ±0.12‰). We attribute this unique K isotopic feature to the presence of abundant djerfisherite inclusions in our sample because this K-bearing sulfide mineral is predicted to be enriched in 39 K during equilibrium exchange with silicates.

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“…Recent studies have shown that reverse weathering reactions majorly affect the clay composition of sediments along continental margins (Baldermann et al, ; Dunlea et al, ; Ehlert et al, ; Rahman et al, ; Santiago Ramos et al, ; Wallmann et al, ). Moreover, Tosca et al () demonstrated that authigenic clays can form from dissolved constituents, not requiring Al or precursor phases.…”

Section: Discussionmentioning

confidence: 99%

¹⁰Be/⁹Be Ratios Reveal Marine Authigenic Clay Formation

Bernhardt

Oelze

Bouchez

et al. 2020

Geophysical Research Letters

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As reverse weathering has been shown to impact long‐term changes in atmospheric CO2 levels, it is crucial to develop quantitative tools to reconstruct marine authigenic clay formation. We explored the potential of the beryllium (Be) isotope ratio (10Be/9Be) recorded in marine clay‐sized sediment to track neoformation of authigenic clays. The power of such proxy relies on the orders‐of‐magnitude difference in 10Be/9Be ratios between continental Be and Be dissolved in seawater. On marine sediments collected along a Chilean margin transect we chemically extracted reactive phases and separated the clay‐sized fraction to compare the riverine and marine 10Be/9Be ratio of this fraction. 10Be/9Be ratios increase fourfold from riverine to marine sediment. We attribute this increase to the incorporation of Be high in 10Be/9Be from dissolved biogenic opal, which also serves as a Si‐source for the precipitation of marine authigenic clays. 10Be/9Be ratios thus sensitively track reverse‐weathering reactions forming marine authigenic clays.

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Reverse weathering in marine sediments and the geochemical cycle of potassium in seawater: Insights from the K isotopic composition (41K/39K) of deep-sea pore-fluids

Cited by 77 publications

References 69 publications

High-precision ⁴¹K/³⁹K measurements by MC-ICP-MS indicate terrestrial variability of δ⁴¹K

High-precision ⁴¹K/³⁹K measurements by MC-ICP-MS indicate terrestrial variability of δ⁴¹K

Potassium isotopic compositions of enstatite meteorites

¹⁰Be/⁹Be Ratios Reveal Marine Authigenic Clay Formation

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Reverse weathering in marine sediments and the geochemical cycle of potassium in seawater: Insights from the K isotopic composition (41K/39K) of deep-sea pore-fluids

Cited by 77 publications

References 69 publications

High-precision 41K/39K measurements by MC-ICP-MS indicate terrestrial variability of δ41K

High-precision 41K/39K measurements by MC-ICP-MS indicate terrestrial variability of δ41K

Potassium isotopic compositions of enstatite meteorites

10Be/9Be Ratios Reveal Marine Authigenic Clay Formation

Contact Info

Product

Resources

About

High-precision ⁴¹K/³⁹K measurements by MC-ICP-MS indicate terrestrial variability of δ⁴¹K

High-precision ⁴¹K/³⁹K measurements by MC-ICP-MS indicate terrestrial variability of δ⁴¹K

¹⁰Be/⁹Be Ratios Reveal Marine Authigenic Clay Formation