Boron isotopes and B/Ca in benthic foraminifera: Proxies for the deep ocean carbonate system

Rae, James; Foster, Gavin L.; Schmidt, Daniela N.; Elliott, Tim

doi:10.1016/j.epsl.2010.12.034

Cited by 252 publications

(307 citation statements)

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“…Such ratios, equivalent to ~30 ppm of boron for the most calcite-rich samples (~30%) are clearly lower than values observed for modern Porites (Douville et al, 2010;Gaillardet and Allegre, 1995;Hemming and Hanson, 1992) but are similar to concentrations measured in some calcite benthic foraminifera (Rae et al, 2011;Yu et al, 2007;Yu et al, 2010) and in inorganic calcite (Gabitov et al, 2014).…”

Section: Impact On δ 11 B B/ca and Reconstructed Phmentioning

confidence: 74%

“…(Douville et al, 2010;Hemming et al, 1998;Krief et al, 2010;Pelejero et al, 2005;Shinjo et al, 2013b;Wei et al, 2009) (Lécuyer et al, 2002;Penman et al, 2013).Benthic foraminifera calcite presentlower δ 11 B (14-17‰), except for the high-magnesium calcite of large foraminifera (26‰),whilehigher values (21-25‰) were measured on planktonic species (Holcomb et al, 2015;Hönisch et al, 2008;Rae et al, 2011;Sanyal et al, 1996). For gorgonian calcite corals, recent studies of the genus Keratoisis (bamboo coral) revealed low values of δ 11 B, between 14 and 17‰ (Farmer et al, 2015).…”

Section: Impact On δ 11 B B/ca and Reconstructed Phmentioning

confidence: 99%

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Intra-skeletal calcite in a live-collected Porites sp.: Impact on environmental proxies and potential formation process

Lazareth

Soares-Pereira

Douville

et al. 2016

Geochimica et Cosmochimica Acta

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Geochemical proxies measured in the carbonate skeleton of tropical coral Porites sp. have commonly been used to reconstruct sea surface temperature (SST) and more recently seawater pH. Nevertheless, both reconstructed SST and pH depend on the preservation state of the skeleton, here made of aragonite; i.e., diagenetic processes and its related effects should be limited. In this study, we report on the impact of the presence of intra-skeletal calcite on the skeleton geochemistry of a live-collected Porites sp..The Porites skeleton preservation state was analyzed using X-ray diffraction and scanning electron microscopy. Sr/Ca, Mg/Ca, U/Ca, Ba/Ca, Li/Mg, and B/Ca ratios were measured at a monthly and yearly resolution using solution ICP-MS and multi-collector ICP-MS. Theδ 11 B signatures and the calcite percentages were acquired at a yearly timescale. The coral colony presents two parts, one with less than 3% calcite (referred to as "no-calcite" skeleton), the other one, corresponding to the skeleton formed during the last 4 yrs. of growth,with calcite percentages varying from 13 to 32% (referred to as "with calcite" skeleton). This intra-skeletal calcite replaces partly or completely numerouscenter of calcification (COCs). All geochemical tracers investigated are significantlyimpacted by the presence of calcite. Thereconstructed SSTdecreasesby about0.1°C per calcite-percent as inferred fromthe Sr/Ca ratio. Such impact reaches up to 0.26°C per calcite-percent for temperature deduced from the Li/Mg ratio. So, less than 5% of such intra-skeletal calcite does not prevent SST reconstructions using Sr/Ca ratio, but the percentage and type of calcite have to be determined before fine SST interpretation. Seawater pH reconstruction inferredfrom boron isotopes drop by about -0.011 pH-unit per calcitepercent. Such sensitivity to calcite presence is particularly dramatic for fine paleo-pH reconstructions. Here we suggest that after being brought to shallow waters following a cyclone, the studied coral was seasonally subjected to rainfall-related water freshening that could have mimicked a vadose environment like can be encountered on raised fossil coral reefs. Nevertheless, the process of calcite precipitation remains to be determined.

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Section: Impact On δ 11 B B/ca and Reconstructed Phmentioning

confidence: 74%

Section: Impact On δ 11 B B/ca and Reconstructed Phmentioning

confidence: 99%

Intra-skeletal calcite in a live-collected Porites sp.: Impact on environmental proxies and potential formation process

Lazareth

Soares-Pereira

Douville

et al. 2016

Geochimica et Cosmochimica Acta

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“…CO 2 uncertainty into our estimates of atmospheric CO 2 using δ 11 B. Splits for elemental and δ 11 B analyses were cleaned following established methods [38][39][40] . Trace-element ratios were determined as in ref.…”

Section: Site Informationmentioning

confidence: 99%

Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

Anagnostou

John

Edgar

et al. 2016

Nature

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363

377

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The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago) 1 , was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period 2-4 . Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO 2 ) levels during the Eocene at 500-3,000 parts per million [5][6][7] , and in the absence of tighter constraints carbon-climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments 8-11 to generate a new high-fidelity record of CO 2 concentrations using the boron isotope (δ 11 Β) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates 6 . Although species-level uncertainties make absolute values difficult to constrain, CO 2 concentrations during the EECO were around 1,400 parts per million. The relative decline in DOI: 10.1038/nature17423 Page 2 of 38 CO 2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene 12 . Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period 13 , this CO 2 decline was sufficient to drive the well documented high-and low-latitude cooling that occurred through the Eocene 14 . Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed 2-4 , both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO 2 doubling (66 per cent confidence), which is similar to the canonical range (1.5 to 4.5 degrees Celsius 15 ), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO 2 concentrations, and that climate sensitivity was relatively constant throughout this period.Over the past 540 million years, Earth's climate has oscillated between a globally warm 'greenhouse state' and an 'icehouse state' with substantial continental glaciation 16 . The most recent of these transitions occurred between the warmest time interval of the last 65 million years-the EECO (about 14 ± 3 °C warmer than preindustrial times 2 )-and the rapid growth of ice on Antarctica in the earliest icehouse state of the Oligocene (~33.6 Myr ago 1 ). It has been suggested that variations in the concentration of the greenhouse gas CO 2 were responsible for both the overall warmth of the Eocene and the subsequent cooling 17 . Recent studies have documented the importance of CO 2 decline for the final step into the icehous...

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“…Table 1 Pressure dependent coefficients for the dissociation constants of acids in seawater, after Millero (1995). For boric acid, a 2 × 10 3 has been changed from 2.608 to −2.608 (m 3°C−2 mol −1 ) (Rae et al, 2011 The scenarios considered in this study are a control scenario for a generic deep ocean setting, a glacial scenario and a phytodetritus layer environment scenario. The changes in the different model parameters associated with the scenarios are shown in Table 3.…”

Section: Model Input Parametersmentioning

confidence: 99%

Modelling δ13C in benthic foraminifera: Insights from model sensitivity experiments

Hesse

Wolf-Gladrow

Lohmann

et al. 2014

Marine Micropaleontology

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The δ 13 C value measured on benthic foraminiferal tests is widely used by palaeoceanographers to reconstruct the distribution of past water masses. The biogeochemical processes involved in forming the benthic foraminiferal δ 13 C signal (δ 13 C foram ), however, are not fully understood and a sound mechanistic description is still lacking. We use a reaction-diffusion model for calcification developed by Wolf-Gladrow et al. (1999) and Zeebe et al. (1999) in order to quantify the effects of different physical, chemical, and biological processes on δ 13 C foram of an idealised benthic foraminiferal shell. Changes in the δ 13 C value of dissolved inorganic carbon (δ 13 C DIC ) cause equal changes in δ 13 C foram in the model. The results further indicate that temperature, respiration rate, and pH have a significant impact on δ 13 C foram . In contrast, salinity, pressure, the δ 13 C value of particulate organic carbon (δ 13 C POC ), total alkalinity, and calcification rate show only a limited influence. In sensitivity experiments we assess how combining these effects can influence δ 13 C foram . We can potentially explain 33 to 47% of the interglacial-to-glacial decrease in δ 13 C foram by changes in temperature and pH, without invoking changes in δ 13 C DIC . Furthermore, about a quarter of the −0.4‰ change in δ 13 C foram observed in phytodetritus layers can be accounted for by an increase in respiration rate and a reduction in pH.

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Boron isotopes and B/Ca in benthic foraminifera: Proxies for the deep ocean carbonate system

Cited by 252 publications

References 74 publications

Intra-skeletal calcite in a live-collected Porites sp.: Impact on environmental proxies and potential formation process

Intra-skeletal calcite in a live-collected Porites sp.: Impact on environmental proxies and potential formation process

Changing atmospheric CO2 concentration was the primary driver of early Cenozoic climate

Modelling δ13C in benthic foraminifera: Insights from model sensitivity experiments

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