Environmental and biological controls on Mg and Li in deep-sea scleractinian corals

Case, David H.; Robinson, Laura F.; Auro, Maureen E.; Gagnon, Alex

doi:10.1016/j.epsl.2010.09.029

Cited by 85 publications

(111 citation statements)

References 52 publications

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“…Consequently, the lower overall values of the bomb  14 C peak observed in WMS surface water can be attributed to vertical mixing and equilibration with the depleted subsurface and intermediate waters. Synchronous with the change of the  14 C slope of WMS, a significantly lower temperature is observed in 1963 based on the Li/Mg ratio, which is used here as a reliable temperature proxy (Montagna et al 2009;Case et al 2010) (Figure 3). This temperature decrease is also observed in the surface western Mediterranean during the same period (Sahsamanoglou and Makrogiannis 1992).…”

Section: Uptake Of Bomb Radiocarbon In Mediterranean Seamentioning

confidence: 83%

A High-Resolution Coral-Based Δ14C Record of Surface Water Processes in the Western Mediterranean Sea

Tisnérat‐Laborde

Montagna

McCulloch³

et al. 2013

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ABSTRACT. The first high-resolution time series of pre-and post-bomb radiocarbon measurements is reported for surface waters in the western Mediterranean Sea. The  14 C record was obtained from the aragonite skeleton of Cladocora caespitosa using a 50-yr-old corallite collected in the Ligurian Sea in 1998. Laser-ablation ICP measurements of trace elements (Li/Mg and Sr/Ca) show a strong seasonal variability, enabling the chronology of the  14 C record to be determined at annual timescales. The mean  14 C of pre-bomb surface water is -56 ± 3‰, corresponding to a reservoir age of 262 ± 29 yr. The postbomb maximum occurs in 1972 with a  14 C value of 90‰, significantly lower than the peak of 150‰ observed in the North Atlantic. The dilution of the peak-amplitude of  14 C in western Mediterranean surface waters is attributed to mixing of North Atlantic Central Water inflow with relatively depleted underlying Intermediate Mediterranean and Levantine Intermediate waters. Intensification of this mixing is observed in 1963-1964, consistent with the change in atmospheric circulation from a positive to negative NAO phase (1960)(1961)(1962)(1963)(1964)(1965)(1966)(1967). The post-peak  14 C variability is relatively limited, reflecting mainly local vertical mixing forced by wind stress.

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Section: Uptake Of Bomb Radiocarbon In Mediterranean Seamentioning

confidence: 83%

A High-Resolution Coral-Based Δ14C Record of Surface Water Processes in the Western Mediterranean Sea

Tisnérat‐Laborde

Montagna

McCulloch³

et al. 2013

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“…Variation of the Sr/Ca-SST dependency limits the proxy accuracy and therewith its utility, particularly in regions where seasonal temperature changes are limited. Recently, the Li/Mg ratio in aragoniticscleractinian coral skeletonshas been shown to be a species independent SST proxy that could complement previous temperature proxy (Case et al, 2010;Hathorne et al, 2013a;Montagna et al, 2014).To reconstruct the pH of the seawater, the U/Ca ratio in tropical corals was proposed (Inoue et al, 2011) but its strong sensitivity to temperature clearly limitspaleopH applications. Contrarily, boron isotopes in Porites sp.…”

Section: Introductionmentioning

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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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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“…Instead, culture experiments and core top studies have shown that the Li/Ca ratio of foraminifera is influenced by the solution Li/Ca ratio, DIC concentration, and possibly the growth rate (Delaney et al, 1985;Hall and Chan, 2004;Hathorne and James, 2006;Lear and Rosenthal, 2006;Vigier et al, 2015). In contrast, the Li/Mg ratio of corals and foraminifera is more strongly related to temperature than Li/Ca and has been recently proposed as being a reliable proxy for ocean temperature (Bryan and Marchitto, 2008;Case et al, 2010;Montagna et al, 2014;Rollion-Bard and Blamart, 2015;Fowell et al, 2016). The Li/Ca ratio of mollusks might be controlled by a combination of vital effects, growth rate, changes in ocean productivity, and/or dissolution of riverine fine sediments within the ocean (Füllenbach et al, 2015;Thébault et al, 2009;Thébault and Chauvaud, 2013).…”

Section: Introductionmentioning

confidence: 99%

The Li isotope composition of marine biogenic carbonates: Patterns and mechanisms

Dellinger

West

Paris

et al. 2018

Geochimica et Cosmochimica Acta

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Little is known about the fractionation of Li isotopes during formation of biogenic carbonates, which form the most promising geological archives of past seawater composition.Here we investigated the Li isotope composition (δ 7 Li) and Li/Ca ratios of organisms that are abundant in the Phanerozoic record, mollusks (mostly bivalves), echinoderms, and brachiopods. The measured samples include (i) modern calcite and aragonite shells from variable species and natural environments (13 mollusk samples, 5 brachiopods and 3 echinoderms), and (ii) shells from organisms grown under controlled conditions at various temperatures. When possible, the mollusk shell ultrastructure was micro-sampled in order to assess intra-shell heterogeneity. In this paper, we systematically characterize the respective influence of mineralogy, temperature, and biological processes on the δ 7 Li and Li/Ca of these shells and compare with published data for other taxa (foraminifera and corals).Aragonitic mollusks have the lowest δ 7 Li, ranging from +16 to +22‰, echinoderms have constant δ 7 Li of about +24‰, brachiopods have δ 7 Li of +25 to +28‰, and finally calcitic mollusks have the largest range and highest δ 7 Li values, ranging from +25‰ to +40‰. Measured brachiopods have similar δ 7 Li compared to inorganic calcite precipitated from seawater (δ 7 Li of +27 to +29‰), indicating minimum influence of vital effects, as also observed for other isotope systems and making them a potentially viable proxy of past seawater composition. Calcitic mollusks, on the contrary, are not a good archive for seawater paleo-δ 7 Li because many samples have significantly higher δ 7 Li values than inorganic calcite and display large inter-species variability, which suggest large vital effects. In addition, we observe very large intra-shell variability, in particular for mixed calcitearagonite shells (over 20‰ variability), but also in mono-mineralic shells (up to 12‰ variability). Aragonitic bivalves have less variable δ 7 Li (7‰ variability) compared to calcitic mollusks, but with significantly lower δ 7 Li compared to inorganic aragonite, indicating the existence of vital effects. Bivalves grown at various temperatures show that temperature has only a minor influence on fractionation of Li isotopes during shell precipitation. Interestingly, we observe a strong correlation (R 2 =0.83) between the Li/Mg ratio in bivalve Mytilus edulis and temperature with potential implications for paleo-temperature reconstructions.Finally, we observe a negative correlation between the δ 7 Li and both the Li/Ca and Mg/Ca ratio of calcite mollusks, which we relate to biomineralization processes.

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Environmental and biological controls on Mg and Li in deep-sea scleractinian corals

Cited by 85 publications

References 52 publications

A High-Resolution Coral-Based Δ14C Record of Surface Water Processes in the Western Mediterranean Sea

A High-Resolution Coral-Based Δ14C Record of Surface Water Processes in the Western Mediterranean Sea

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

The Li isotope composition of marine biogenic carbonates: Patterns and mechanisms

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