Low temperature stable mineral recrystallization of foraminiferal tests and implications for the fidelity of geochemical proxies

Chanda, Piyali; Gorski, Christopher A.; Oakes, Rosie L.; Fantle, Matthew S.

doi:10.1016/j.epsl.2018.11.011

Cited by 38 publications

(32 citation statements)

References 46 publications

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“…Even if the porewater surrounding the foraminifera tests maintain a constant chemical and isotopic composition, increased temperatures during the burial will lead to isotopic disequilibrium between the test calcite and the porewater, which drives isotopic exchange 27 . Therefore, consistent with the results of Bernard et al 27 and Chanda et al 28 , our results make the case that partial isotopic exchange of foraminifera tests is unavoidable under natural conditions during diagenesis. We furthermore demonstrate that susceptibility to isotopic exchange is species-specific.…”

Section: Discussionsupporting

confidence: 93%

“…Magnesium can substitute for Ca in the calcite lattice 54 , but is also concentrated within the organic linings 41 . Chanda et al 28 argued that stable mineral recrystallization of foraminifera tests proceeds through the preferential dissolution of Mg- and Sr-rich calcite by a dissolution-precipitation mechanism. However, our NanoSIMS images indicate that Mg- and S-rich bands are broader and more numerous than the 18 O-enrichment bands, and the tests do not show evidence of any significant dissolution or precipitation (Supplementary Figs.…”

Section: Discussionmentioning

confidence: 99%

“…The banded distributions of these elements reflect, to different degrees, the presence and distribution of organic matter within the test wall 22 , 24 – 26 . This ultrastructure creates a very large internal surface on which elemental and isotopic exchange with sediment porewater can take place, provided that this water can penetrate deep enough into the structure, which seems to be the case according to several recent studies 27 , 28 .…”

Section: Introductionmentioning

confidence: 92%

“…The rapid isotopic exchange between carbonate and an aqueous phase has subsequently been experimentally confirmed for a series of carbonate minerals at much lower temperatures (down to room temperature), on time scales never exceeding a few months. Chanda et al 28 used 45 Ca as a radiotracer to investigate the recrystallization of planktonic foraminifera tests in seawater analogues in equilibrium with calcite at 25 °C. The radiotracer was incorporated into the biocalcite within days with minimal structural change and it was concluded that intra-test chemical heterogeneities played a key role in the recrystallization of these tests.…”

Section: Introductionmentioning

confidence: 99%

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Fast and pervasive diagenetic isotope exchange in foraminifera tests is species-dependent

et al. 2022

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Oxygen isotope compositions of fossil foraminifera tests are commonly used proxies for ocean paleotemperatures, with reconstructions spanning the last 112 million years. However, the isotopic composition of these calcitic tests can be substantially altered during diagenesis without discernible textural changes. Here, we investigate fluid-mediated isotopic exchange in pristine tests of three modern benthic foraminifera species (Ammonia sp., Haynesina germanica, and Amphistegina lessonii) following immersion into an 18O-enriched artificial seawater at 90 °C for hours to days. Reacted tests remain texturally pristine but their bulk oxygen isotope compositions reveal rapid and species-dependent isotopic exchange with the water. NanoSIMS imaging reveals the 3-dimensional intra-test distributions of 18O-enrichment that correlates with test ultra-structure and associated organic matter. Image analysis is used to quantify species level differences in test ultrastructure, which explains the observed species-dependent rates of isotopic exchange. Consequently, even tests considered texturally pristine for paleo-climatic reconstruction purposes may have experienced substantial isotopic exchange; critical paleo-temperature record re-examination is warranted.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Fast and pervasive diagenetic isotope exchange in foraminifera tests is species-dependent

et al. 2022

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“…Oelkers et al (2019) reported the rapid resetting of the Ca isotope compositions of calcite in aqueous solutions that were in chemical equilibrium, but isotope disequilibrium with the mineral. The rapid alteration of the calcium isotope compositions of foraminiferal test at ambient temperatures at near to bulk equilibrium conditions, but in the presence of isotopically distinct fluids, was reported by Chanda et al (2019). The change in isotope composition of minerals at bulk chemical equilibrium is also the basis for determining experimentally equilibrium isotope fractionation factors using the three-isotope method (e.g., Beard et al, 2010;Li et al, 2011;Frierdich et al, 2014;Stamm et al, 2019Stamm et al, , 2020.…”

Section: Introductionmentioning

confidence: 92%

The temporal evolution of the carbon isotope composition of calcite in the presence of cyanobacteria

Grimm

Mavromatis

Leis³

et al. 2021

Chemical Geology

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Quantifying the link between cyanobacterial activity and the carbon isotope signature of precipitated carbonate minerals is crucial for reconstructing the environmental conditions present at the time of carbonate mineral formation. In this study, calcite was precipitated in the presence and absence of Synechococcus sp. cyanobacteria in batch reactors. The temporal evolution of the carbon isotope composition of calcite ( 13 CCalcite) and dissolved inorganic carbon ( 13 CDIC) was monitored to evaluate the rate and degree to which the carbon isotope compositions in calcite are modified during and after its precipitation. The presence of cyanobacteria promoted calcium carbonate formation by increasing fluid pH and the CaCO3 saturation state. It also changed significantly the carbon isotope composition of dissolved inorganic carbon due to the preferential incorporation of 12 C into the biomass. This generated an isotope disequilibrium between the calcite and the aqueous fluid phase over time after the calcite precipitated. The carbon isotope composition of the calcite evolved continuously towards mineral-fluid isotope equilibrium after its precipitation, at geometric surface area normalized rates ranging from 1.75×10 -14 to 1.71×10 -13 mol 13 C/m 2 /s. These rates are sufficiently fast such that the  13 CDIC value of aqueous fluids in calcite-rich rocks would be buffered by the  13 CCalcite value of the co-existing calcite. Mass balance calculations suggest that the carbon isotope composition of calcite could change noticeably when the calcite is in isotope disequilibrium with its co-existing fluid, for example through the presence of a local 12 C sink such as photosynthetic microorganisms or 12 C source such as decomposition of organic material. KeywordsCarbon isotopes, calcite, cyanobacteria, isotope re-equilibration 13 ) as summarized in Fig. 1. The δ C DIC 13values in these experiments are initially controlled by the carbon isotope composition of the carbonate and bicarbonate powder added to water to produce the initial reactive fluids. This value is subsequently influenced by 1) carbon exchange with the atmospheric CO 2 that was continuously bubbled in the reactors, 2) photosynthetic uptake of DIC by growing cyanobacteria, 3) live cell respiration and dead cell lysis together with the subsequent heterotrophic degradation of organic compounds to dissolved carbon species, and 4) DIC removal from the fluid by calcite precipitation. These processes are described in detail in the following section. Equilibrium fractionation between atmosphericCO2 and DIC An estimate of δ C DIC 13 values in equilibrium with the atmosphere can be made by taking account of the distinct equilibrium fractionation factors of each major carbon species present in the aqueous fluids using (Myrttinen et al., 2012): δ 13 C DIC = ∑ (𝑥 𝑖 • (δ 13 C CO 2 + 10 3 ln α 13 C 𝑖−CO 2(g) )) 𝑖 ,where 𝑥 𝑖 designates the mole fraction of the ith aqueous carbon species and δ 13 C CO 2 designates the carbon isotope composition of atmospheric CO 2 , which wa...

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Demystifying diagenesis: The future of diagenetic inquiry in the geosciences

Fantle,

Lloyd

2025

Treatise on Geochemistry

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Low temperature stable mineral recrystallization of foraminiferal tests and implications for the fidelity of geochemical proxies

Cited by 38 publications

References 46 publications

Fast and pervasive diagenetic isotope exchange in foraminifera tests is species-dependent

Fast and pervasive diagenetic isotope exchange in foraminifera tests is species-dependent

The temporal evolution of the carbon isotope composition of calcite in the presence of cyanobacteria

Demystifying diagenesis: The future of diagenetic inquiry in the geosciences

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