Atmospheric
            <sup>14</sup>
            C/
            <sup>12</sup>
            C changes during the last glacial period from Hulu Cave

Cheng, Hai; Edwards, R. Lawrence; Southon, John; Matsumoto, Katsumi; Feinberg, Joshua M.; Sinha, Ashish; Zhou, Wei; Li, Hanying; Li, Xianglei; Xu, Yao; Chen, Shitao; Tan, Ming; Wang, Quan; Wang, Yongjin; Ning, Youfeng

doi:10.1126/science.aau0747

Cited by 100 publications

(101 citation statements)

References 51 publications

(36 reference statements)

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“…Different pathways of carbonate dissolution affect the carbon isotope composition of drip water (Hendy, 1971;Fohlmeister et al, 2010;Minami et al, 2015). Carbonate dissolution conditions can be similar in the same cave for the same time period, as deduced by radiocarbon reservoir effects of contemporaneously growing speleothems from the same cave (e.g., Fohlmeister et al, 2012;Lechleitner et al, 2016;Cheng et al, 2018;Riechelmann et al, 2019). Furthermore, modelling studies have shown that slight differences in carbonate dissolution conditions have only a small effect on δ 13 C values (Hendy, 1971;Fohlmeister et al, 2011;Griffiths et al, 2012).…”

Section: Influence Of Carbonate Dissolution Conditionsmentioning

confidence: 99%

Main controls on the stable carbon isotope composition of speleothems

Fohlmeister

Voarintsoa

Lechleitner

et al. 2020

Geochimica et Cosmochimica Acta

125

103

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The climatic controls on the stable carbon isotopic composition (δ 13 C) of speleothem carbonate are less often discussed in the scientific literature in contrast to the frequently used stable oxygen isotopes. Various local processes influence speleothem δ 13 C values and confident and detailed interpretations of this proxy are often complex. A better understanding of speleothem δ 13 C values is critical to improving the amount of information that can be gained from existing and future records.This contribution aims to disentangle the various processes governing speleothem δ 13 C values and assess their relative importance. Using a large data set of previously published records we examine the spatial imprint of climate-related processes in speleothem δ 13 C values deposited post-1900 CE, a period during which global temperature and climate data is readily available. Additionally, we investigate the causes for differences in average δ 13 C values and growth rate under identical climatic conditions by analysing pairs of contemporaneously deposited speleothems from the same caves.This approach allows to focus on carbonate dissolution and fractionation processes during carbonate precipitation, which we evaluate using existing geochemical models. Our analysis of a large global data set of records reveals evidence for a temperature control, likely driven by vegetation and soil processes, on δ 13 C values in recently deposited speleothems. Moreover, datamodel intercomparison shows that calcite precipitation occurring along water flow paths prior to reaching the top of the speleothem can explain the wide δ 13 C range observed for concurrently deposited samples from the same cave. We demonstrate that using the combined information of contemporaneously growing speleothems is a powerful tool to decipher controls on δ 13 C values, which facilitates a more detailed discussion of speleothem δ 13 C values as a proxy for climate conditions and local soil-karst processes.

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Section: Influence Of Carbonate Dissolution Conditionsmentioning

confidence: 99%

Main controls on the stable carbon isotope composition of speleothems

Fohlmeister

Voarintsoa

Lechleitner

et al. 2020

Geochimica et Cosmochimica Acta

125

103

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“…The occurrence of a higher abundance of Neogloboquadrina pachyderma (dextral), e.g., during warmer intervals, such as the Bölling-Alleröd (B/A), has been challenging to explain. On the other hand, paired measurements of 14 C/ 12 C and 230 Th ages from Hulu Cave stalagmites suggest magnetic field changes have greatly contributed to high atmospheric 14 C/ 12 C values at HS4 and the Younger Dryas (YD) (Cheng et al, 2018). Thus a constant reservoir age ( R = 0) assumed when calibrating foraminiferal radiocarbon dates using CALIB 6 software and the Marine 13 calibration dataset (Reimer et al, 2013) for core CSH1 may cause large chronological uncertainties.…”

Section: Chronostratigraphy Of Core Csh1mentioning

confidence: 99%

Millennial-scale variations in sedimentary oxygenation in the western subtropical North Pacific and its links to North Atlantic climate

et al. 2020

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The deep-ocean carbon cycle, especially carbon sequestration and outgassing, is one of the mechanisms to explain variations in atmospheric CO 2 concentrations on millennial and orbital timescales. However, the potential role of subtropical North Pacific subsurface waters in modulating atmospheric CO 2 levels on millennial timescales is poorly constrained. An increase in the respired CO 2 concentration in the glacial deep-ocean due to biological pump generally corresponds to deoxygenation in the ocean interior. This link thus offers a chance to study oceanic ventilation and coeval export productivity based on redox-controlled sedimentary geochemical parameters. Here, we investigate a suite of geochemical proxies in a sediment core from the Okinawa Trough to understand sedimentary oxygenation variations in the subtropical North Pacific over the last 50 000 years (50 ka). Our results suggest that enhanced mid-depth western subtropical North Pacific (WSTNP) sedimentary oxygenation occurred during cold intervals and after 8.5 ka, while oxygenation decreased during the Bölling-Alleröd (B/A) and Preboreal. The enhanced oxygenation during cold spells is linked to the North Pacific Intermediate Water (NPIW), while interglacial increase after 8.5 ka is linked to an intensification of the Kuroshio Current due to strengthened northeast trade winds over the tropics. The enhanced formation of the NPIW during Heinrich Stadial 1 (HS1) was likely driven by the perturbation of sea ice formation and sea surface salinity oscillations in the high-latitude North Pacific. The diminished sedimentary oxygenation during the B/A due to a decreased NPIW formation and enhanced export production, indicates an expansion of the oxygen minimum zone in the North Pacific and enhanced CO 2 sequestration at mid-depth waters, along with the termination of atmospheric CO 2 concentration increase. We attribute the millennial-scale changes to an intensified NPIW and enhanced abyss flushing during deglacial cold and warm intervals, respectively, closely related to variations in North Atlantic Deep Water formation.

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Section: Discussionmentioning

confidence: 99%

“…Cave bear bones from excavation site 2 yielded moderate to low N values suggesting variably low collagen preservation. Radiocarbon data of three samples with relatively high N values indicate that they are probably older than about 50k cal a BP (Cheng et al, 2018). 230 Th/U analyses do not date the bones directly, but allow to narrow down the time interval of cave bear occupation.…”

Section: Assessment Of Age Datamentioning

confidence: 99%

Cave bear occupation in Schwabenreith Cave, Austria, during the early last glacial: constraints from ²³⁰Th/U‐dated speleothems

Spötl

Rabeder

Reimer

2019

J Quaternary Science

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The cave bear was a prominent member of the Upper Pleistocene fauna in Eurasia. While breakthroughs were recently achieved with respect to its phylogeny using ancient DNA techniques, it is still challenging to date cave bear fossils beyond the radiocarbon age range. Without an accurate and precise chronological framework, however, key questions regarding the palaeoecology cannot be addressed, such as the extent to which large climate swings during the last glacial affected the habitat and possibly even conditioned the final extinction of this mammal. Key to constraining the age of cave bear fossils older than the lower limit of radiocarbon dating is to date interlayered speleothems using 230Th/U. Here we report new results from one such site in the Eastern European Alps (Schwabenreith Cave), which yielded the highest density of bones of cave bear (Ursus spelaeus eremus). Although dating of the flowstones overlying this fossiliferous succession was partly compromised by diagenetic alteration, the 230Th/U dates indicate that the bear hibernated in this cave after about 113 ka and before about 109 ka. This time interval coincides with the equivalent of Greenland Stadial 25, suggesting possible climate control on the cave bear's habitat and behaviour. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd

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Atmospheric ¹⁴ C/ ¹² C changes during the last glacial period from Hulu Cave

Cited by 100 publications

References 51 publications

Main controls on the stable carbon isotope composition of speleothems

Main controls on the stable carbon isotope composition of speleothems

Millennial-scale variations in sedimentary oxygenation in the western subtropical North Pacific and its links to North Atlantic climate

Cave bear occupation in Schwabenreith Cave, Austria, during the early last glacial: constraints from ²³⁰Th/U‐dated speleothems

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Atmospheric 14 C/ 12 C changes during the last glacial period from Hulu Cave

Cited by 100 publications

References 51 publications

Main controls on the stable carbon isotope composition of speleothems

Main controls on the stable carbon isotope composition of speleothems

Millennial-scale variations in sedimentary oxygenation in the western subtropical North Pacific and its links to North Atlantic climate

Cave bear occupation in Schwabenreith Cave, Austria, during the early last glacial: constraints from 230Th/U‐dated speleothems

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Product

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Atmospheric ¹⁴ C/ ¹² C changes during the last glacial period from Hulu Cave

Cave bear occupation in Schwabenreith Cave, Austria, during the early last glacial: constraints from ²³⁰Th/U‐dated speleothems