Iodate in calcite, aragonite and vaterite CaCO3: Insights from first-principles calculations and implications for the I/Ca geochemical proxy

Feng, Xiaolei; Redfern, Simon A. T.

doi:10.1016/j.gca.2018.02.017

Cited by 55 publications

(27 citation statements)

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“…The residence time of iodine in modern ocean is ~300 kyr, leading to a generally global uniform total iodine concentration of ~0.45 μmol (Broecker & Peng, ; Campos et al, ). Experimental and computational work has demonstrated that IO 3 − is the dominant ion incorporated into calcite through replacing carbonate ion (e.g., Feng & Redfern, ; Lu et al, ; Podder et al, ). Therefore, stratigraphic I/Ca trends are mostly controlled by changes in IO 3 − concentrations in the local water column (e.g., Hardisty et al, ; Lu et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…). Experimental and computational work has demonstrated that IO 3 − is the dominant ion incorporated into calcite through replacing carbonate ion (e.g.,Feng & Redfern, 2018 ;Lu et al, 2010;Podder et al, 2017). Therefore, stratigraphic I/Ca trends are mostly controlled by changes in IO 3 − concentrations in the local water column (e.g.,Hardisty et al, 2017;Lu et al, 2010).…”

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confidence: 99%

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Intensified Ocean Deoxygenation During the end Devonian Mass Extinction

Liu

Luo

et al. 2019

Geochem Geophys Geosyst

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The end-Devonian mass extinction (~359 Ma) substantially impacted marine ecosystems and shaped the roots of modern vertebrate biodiversity. Although multiple hypotheses have been proposed, no consensus has been reached about the mechanism inducing this extinction event. In this study, I/Ca ratio of carbonate was used to unravel the changes in local oxygen content of the upper water column during this critical interval. The Devonian-Carboniferous boundary was recorded in two shallow water carbonate sections in south China. I/Ca values at both locations show a clear decline in the Middle and Upper Siphonodella praesulcata conodont zones, which coincides with a positive shift in carbonate carbon isotope composition and a negative shift in nitrogen isotope composition. These results suggest that deoxygenation was intensified during this critical interval, which likely influenced shallow water habitats, lending support to the notion that oxygen deficiency likely was a direct mechanism impacting the end-Devonian mass extinction.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Intensified Ocean Deoxygenation During the end Devonian Mass Extinction

Liu

Luo

et al. 2019

Geochem Geophys Geosyst

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“…The carbon atoms accept electrons from yttrium as they populate sp 2− orbitals. We have carried out a Bader charge analysis (Supplementary Figure 5) of our structures as a function of pressure 20 . At ambient pressure, each C atom accepts 0.9 electrons from Y, with an electron loss of 1.8 electrons from each Y.…”

Section: Discussionmentioning

confidence: 99%

Carbon network evolution from dimers to sheets in superconducting ytrrium dicarbide under pressure

Feng

Pickard

et al. 2018

Commun Chem

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Carbon-bearing compounds display intriguing structural diversity, due to variations in hybrid bonding of carbon. Here, first-principles calculations and unbiased structure searches on yttrium dicarbide at pressure reveal four new structures with varying carbon polymerisation, in addition to the experimentally observed high-temperature low-pressure I4/mmm dimer phase. At low pressures, a metallic C2/m phase (four-member single-chain carbide) is stable, which transforms into a Pnma phase (single-chain carbide) upon increasing pressure, with further transformation to an Immm structure (double-chain carbide) at 54 GPa and then to a P6/mmm phase (sheet carbide) at 267 GPa. Yttrium dicarbide is structurally diverse, with carbon bonded as dimers (at lowest pressure), four-member single chains, infinite single chains, double chains and eventually sheet structures on compression. Electron-phonon coupling calculations indicate that the high-pressure phases are superconducting. Our results aid the understanding and design of new superconductors and illuminate pressure-induced carbon polymerisation in carbides.

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“…Iodate is completely reduced to iodide in anoxic waters, and re-oxidized under well-oxygenated conditions (Rue et al, 1997). Only IO 3 is incorporated into the calcite structure (Lu et al, 2010) by substituting for the CO 3 2ion (Feng and Redfern, 2018;Podder et al, 2017). Higher foraminiferal I/Ca values thus generally record higher IO 3 concentrations in seawater, and therefore indicate better-oxygenated water conditions.…”

Section: Introductionmentioning

confidence: 99%

Refining the planktic foraminiferal I/Ca proxy: Results from the Southeast Atlantic Ocean

Dickson

Thomas

et al. 2020

Geochimica et Cosmochimica Acta

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Profound changes in upper ocean oxygenation have taken place in recent decades and are expected to continue in the future, but the complexity of the processes driving these changes has yet to be fully unraveled. Planktic foraminiferal I/Ca is a promising tool to reconstruct the extent of past upper ocean oxygenation, but a thorough assessment is necessary to evaluate both its potential and its limitations. We used foraminifers from Holocene core-tops (Southeast Atlantic Ocean) to document planktic I/Ca across a range of oceanographic conditions. Subsurface O 2 concentrations may be the dominant control on planktic foraminiferal I/Ca and planktic I/Ca decreases rapidly at low O 2 conditions (O 2 < ~70-100 µmol/kg). We thus document that low planktic I/Ca can be used empirically to indicate hypoxia in the upper water column, but questions remain as to the mechanistic understanding of the relation between seawater iodine speciation change, its O 2 threshold and foraminiferal I/Ca. Planktic I/Ca records from core *Manuscript 2 GeoB1720-2 (Benguela Upwelling System, SE Atlantic) suggest that hypoxic waters were present near the site persistently during the last 240 ka, without clear glacial-interglacial variability.

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Iodate in calcite, aragonite and vaterite CaCO3: Insights from first-principles calculations and implications for the I/Ca geochemical proxy

Cited by 55 publications

References 50 publications

Intensified Ocean Deoxygenation During the end Devonian Mass Extinction

Intensified Ocean Deoxygenation During the end Devonian Mass Extinction

Carbon network evolution from dimers to sheets in superconducting ytrrium dicarbide under pressure

Refining the planktic foraminiferal I/Ca proxy: Results from the Southeast Atlantic Ocean

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