High precision U-series dating of scleractinian cold-water corals using an automated chromatographic U and Th extraction

Wefing, Anne-Marie; Arps, Jennifer; Blaser, Patrick; Wienberg, Claudia; Hebbeln, Dierk; Frank, Norbert

doi:10.1016/j.chemgeo.2017.10.036

Cited by 53 publications

(50 citation statements)

References 33 publications

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“…epibionts, borings, ferro-manganese crusts and coatings) and were then cleaned chemically using weak acid leaching and water rinsing according to the procedure described in Frank et al (2004), recently updated by Wefing et al (2017). The measurements were taken at the Institute for Environmental Physics at Heidelberg University (IUP, Germany) on a multi-collector inductively coupled plasma mass spectrometer (ThermoFisher Neptune plus; Wefing et al 2017). The reproducibility of mass-spectrometric measurements was assessed using the reference material HU-1 (Cheng et al 2000).…”

Section: Th/u Age Determinationsmentioning

confidence: 99%

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Solenosmilia variabilis-bearing cold-water coral mounds off Brazil

et al. 2019

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Cold-water corals (CWC), dominantly Desmophyllum pertusum (previously Lophelia pertusa), and their mounds have been in the focus of marine research during the last two decades; however, little is known about the mound-forming capacity of other CWC species. Here, we present new 230 Th/U age constraints of the relatively rarely studied framework-building CWC Solenosmilia variabilis from a mound structure off the Brazilian margin combined with computed tomography (CT) acquisition. Our results show that S. variabilis can also contribute to mound formation, but reveal coral-free intervals of hemipelagic sediment deposits, which is in contrast to most of the previously studied CWC mound structures. We demonstrate that S. variabilis only occurs in short episodes of \ 4 kyr characterized by a coral content of up to 31 vol%. In particular, it is possible to identify distinct clusters of enhanced aggradation rates (AR) between 54 and 80 cm ka-1. The determined AR are close to the maximal growth rates of individual S. variabilis specimens, but are still up to one order of magnitude smaller than the AR of D. pertusum mounds. Periods of enhanced S. variabilis AR predominantly fall into glacial periods and glacial terminations that were characterized by a 60-90 m lower sea Electronic supplementary material

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Section: Th/u Age Determinationsmentioning

confidence: 99%

“…Nevertheless, a correction for initial 230 Th was applied prior to age determination using a 230 Th/ 232 Th activity ratio of 8 ± 4 (e.g. Mangini et al 2010;Wefing et al 2017).…”

Section: Th/u Age Determinationsmentioning

confidence: 99%

Solenosmilia variabilis-bearing cold-water coral mounds off Brazil

et al. 2019

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“…This change coincides with a doubling of the growth rate from slightly below 0.10 to more than 0.20 mm yr −1 , suggesting that δ 234 U init is influenced by infiltration changes. It may also be affected by the geochemical composition of the seepage water (Zhou et al, 2005). However, in comparison to the other proxies for this record, it appears most likely that the drip rate in Moomi Cave has increased due to higher net infiltration.…”

Section: Climatic Controls Of Dcf At Moomi Cavementioning

confidence: 87%

Climate-induced speleothem radiocarbon variability on Socotra Island from the Last Glacial Maximum to the Younger Dryas

et al. 2020

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In this study, the dead carbon fraction (DCF) variations in stalagmite M1-5 from Socotra Island in the western Arabian Sea were investigated through a new set of highprecision U-series and radiocarbon ( 14 C) dates. The data reveal an extreme case of very high and also climate-dependent DCF. For M1-5, an average DCF of 56.2 ± 3.4 % is observed between 27 and 18 kyr BP. Such high DCF values indicate a high influence of aged soil organic matter (SOM) and nearly completely closed-system carbonate dissolution conditions. Towards the end of the last glacial period, decreasing Mg/Ca ratios suggest an increase in precipitation which caused a marked change in the soil carbon cycling as indicated by sharply decreasing DCF. This is in contrast to the relation of soil infiltration and DCF as seen in stalagmites from temperate zones.

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“…In total, 15 uranium‐series isotope measurements were done on two reef‐forming scleractinian coral species ( Lophelia pertusa and Madrepora oculata ). Prior to measurements, the CWC skeletal fragments were mechanically cleaned using the sandblasting method and chemically cleaned using weak acid leaching and water rinsing as described by Frank et al () and updated by Wefing et al (). The measurements were conducted at the Institute for Environmental Physics at Heidelberg University.…”

Section: Methodsmentioning

confidence: 99%

“…The measurements were conducted at the Institute for Environmental Physics at Heidelberg University. The U‐series isotope analyses were done by multi‐collector inductively coupled plasma mass spectrometry (Thermo Fisher Neptune Plus; Wefing et al, ). Uranium‐series ages were computed using the half‐lives provided by Cheng et al ().…”

Section: Methodsmentioning

confidence: 99%

Constraining the formation of authigenic carbonates in a seepage‐affected cold‐water coral mound by lipid biomarkers

et al. 2020

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Cold‐water coral (CWC) mounds are build‐ups comprised of coral‐dominated intervals alternating with a mixed carbonate‐siliciclastic matrix. At some locations, CWC mounds are influenced by methane seepage, but the impact of methane on CWC mounds is poorly understood. To constrain the potential impact of methane on CWC mound growth, lipid biomarker investigations were combined with mineralogical and petrographic analyses to investigate the anaerobic oxidation of methane (AOM) and authigenic carbonate formation in sediment from a seep‐affected CWC mound in the Gulf of Cadiz. The occurrence of AOM was confirmed by characteristic lipids found within a semi‐lithified zone (SLZ) consisting of authigenic aragonite, high‐magnesium calcite and calcium‐excess dolomite. The formation of high‐Mg calcite is attributed to AOM, acting as a lithifying agent. Aragonite is only a minor phase. Ca‐excess dolomite in the SLZ and upper parts may be formed by organoclastic sulphate reduction, favouring precipitation by increased alkalinity. The AOM biomarkers in the SLZ include isoprenoid‐based archaeal membrane lipids, such as abundant glycerol dibiphytanyl glycerol tetraethers (GDGTs) dominated by GDGT‐2. The δ13C values of GDGT‐2, measured as ether‐cleaved monocyclic biphytanes, are as low as −100‰ versus V‐PDB. Further, bacterial dialkyl glycerol diethers with two anteiso‐C15 alkyl chains and δ13C values of −81‰ are interpreted as biomarkers of sulphate‐reducing bacteria. The lipid biomarker signatures and mineralogical patterns suggest that anaerobic methane‐oxidizing archaea of the ANME‐1 group thrived in the subsurface at times of slow and diffusive methane seepage. Petrographic analyses revealed that the SLZ was exhumed at some point (e.g. signs of bioerosion of the semi‐lithified sediment), providing a hard substrate for CWC larval settlement. In addition, this work reveals that AOM‐induced semi‐lithification likely played a role in mound stabilization. Lipid biomarker analysis proves to be a powerful tool to disentangle early diagenetic processes induced by microbial metabolisms.

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High precision U-series dating of scleractinian cold-water corals using an automated chromatographic U and Th extraction

Cited by 53 publications

References 33 publications

Solenosmilia variabilis-bearing cold-water coral mounds off Brazil

Solenosmilia variabilis-bearing cold-water coral mounds off Brazil

Climate-induced speleothem radiocarbon variability on Socotra Island from the Last Glacial Maximum to the Younger Dryas

Constraining the formation of authigenic carbonates in a seepage‐affected cold‐water coral mound by lipid biomarkers

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