The coupled δ13C-radiocarbon systematics of three Late Glacial/early Holocene speleothems; insights into soil and cave processes at climatic transitions

Rudzka, Dominika; McDermott, Frank; Baldini, Lisa M.; Fleitmann, Dominik; Moreno, Ana; Stoll, Heather

doi:10.1016/j.gca.2011.05.022

Cited by 74 publications

(49 citation statements)

References 57 publications

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“…O'Brien and Stout, 1978) deep in the epikarst might explain the relatively low radiocarbon specific activity in COB caveair CO 2 . The importance of old organic matter oxidation on speleothem carbon isotope compositions has been recently documented (Oster et al, 2010;Rudzka et al, 2011). One scenario that satisfies the observations made in this study is oxidation of $1000 A.D. organic matter below 4 m, at a rate small enough that the weighted mean fmc of CO 2 respired in the entire soil and epikarst column is 1.075 (i.e.…”

Section: Evidence For Ventilationsupporting

confidence: 82%

The sources and sinks of CO2 in caves under mixed woodland and grassland vegetation

Breecker

Payne

Quade

et al. 2012

Geochimica et Cosmochimica Acta

116

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Section: Evidence For Ventilationsupporting

confidence: 82%

The sources and sinks of CO2 in caves under mixed woodland and grassland vegetation

Breecker

Payne

Quade

et al. 2012

Geochimica et Cosmochimica Acta

116

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“…In theory, dissolution can occur under two end member situations (open-or closed-system dissolution) (Hendy, 1971). However, in the real soilkarst environment, carbonate dissolution is likely to occur under an intermediate state between a completely open and a completely closed-system (Rudzka et al, 2011). Under the open-system end member, the DIC maintains isotopic equilibrium with the unlimited reservoir of CO 2,g .…”

Section: Discussionmentioning

confidence: 99%

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Griffiths

Fohlmeister

Drysdale

et al. 2012

Quaternary Geochronology

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a b s t r a c tOver the past decade, a number of speleothem studies have used radiocarbon ( 14 C) to address a range of palaeoclimate problems. These have included the use of the bomb pulse 14 C to anchor chronologies over the last 60 years, the combination of U-Th and 14 C measurements to improve the radiocarbon agecalibration curve, and linking atmospheric 14 C variations with climate change. An issue with a number of these studies is how to constrain, or interpret, variations in the amount of radioactively dead carbon (i.e. the dead carbon fraction, or DCF) that reduces radiocarbon concentrations in speleothems. In this study, we use 14 C, stable-isotopes, and trace-elements in a U-Th dated speleothem from Flores, Indonesia, to examine DCF variations and their relationship with above-cave climate over the late Holocene and modern era. A strong association between the DCF and hydrologically-controlled proxy data suggests that more dead carbon was being delivered to the speleothem during periods of higher cave recharge (i.e. lower d 18 O, d 13 C and Mg/Ca values), and hence stronger summer monsoon. To explore this relationship, we used a geochemical soil-karst model coupled with 14 C measurements through the bomb pulse to disentangle the dominant components governing DCF variability in the speleothem. We find that the DCF is primarily controlled by limestone dissolution associated with changes in open-versus closed-system conditions, rather than kinetic fractionation and/or variations in the age spectrum of soil organic matter above the cave. Therefore, we infer that periods of higher rainfall resulted in a higher DCF because the system was in a more closed state, which inhibited carbon isotope exchange between the karst water dissolved inorganic carbon and soil-gas CO 2 , and ultimately led to a greater contribution of dead carbon from the bedrock.Published by Elsevier B.V.

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“…The Bahamas speleothem GB-89-24-1 is also stable over the Younger Dryas interval, though GB-89-25-3, which has a much higher average DCP, shows large fluctuations in DCP at the YD suggesting that climate did have an effect on DCP in some speleothems in the region during the YD interval. Rudzka et al (2011) N, 3 • 39 W) which also show muted responses to the YD in DCP. There is a decrease of 3.24 ± 2.27% (1σ ) in DCP in the Turkish speleothem, So-1, between the two measurements bracketing the Bølling-Allerød/YD transition (from 9.58 ± 1.87% at 13.1 ka to 6.34 ± 1.29% at 12.8 ka), but DCP rebounds to pre-YD values by the next measurement at 12.4 ka.…”

Section: Climatic Influences On Dcp During the 82 Ka Eventmentioning

confidence: 99%

“…Fohlmeister et al, 2010Fohlmeister et al, , 2011aFohlmeister et al, , 2011bGriffiths et al, 2012, Rudzka et al, 2011Rudzka-Phillips et al, 2013) most often using a simple three-box soil carbon model and the shape of the atmospheric 14 C bomb peak in modern speleothems to estimate the relative size and turnover times of three SOM pools. The models employed in these studies require that the soil CO 2 equilibrating with the soil water DIC have mean ages ranging from ∼40 to 500 years during the twentieth century (Rudzka-Phillips et al, 2013), which appears to be at odds with the observations of soil CO 2 .…”

Section: Climatic Influences On Dcp During the Mid-holocenementioning

confidence: 99%

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

Noronha¹,

Johnson²,

et al. 2014

Earth and Planetary Science Letters

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Recently, it has been shown that U-Th dated speleothems may provide a valuable archive of atmospheric radiocarbon ( 14 C), but the reliability of these records is dependent upon the stability of the dead carbon proportion (DCP) derived from the soil and bedrock. In order to assess climatic influences on speleothem DCP, we have investigated DCP variability over the Holocene interval where atmospheric 14 C is well known based on dendrochronologically dated tree rings by conducting 14 C measurements on a U-Th dated stalagmite (HS4) from Heshang Cave, Hubei Province, China (30 • 27 N, 110 • 25 E; 294 m) spanning 0.5-9.6 ka. We investigated climatic controls on DCP, and found that DCP in HS4 has an average value over the Holocene of 10.3 ± 1.5%, with an average age offset from atmospheric radiocarbon of 875 ± 130 years, and displays a response to both precipitation increases and decreases. HS4 DCP increases during the wetter mid-Holocene interval (∼5.5-7.1 ka), likely reflecting a shift to more closed-system dissolution in response to increased soil moisture. DCP decreases during the 8.2 ka event, a time period of dry conditions at Heshang Cave, though the lower amplitude of this shift indicates that DCP may be less sensitive to dry events. Speleothems are potentially valuable archives of atmospheric radiocarbon, especially in older portions of the 14 C calibration curve where knowledge of atmospheric 14 C is limited, however minor climatic influences on DCP could introduce uncertainties of several hundred years to calibrated ages.

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The coupled δ13C-radiocarbon systematics of three Late Glacial/early Holocene speleothems; insights into soil and cave processes at climatic transitions

Cited by 74 publications

References 57 publications

The sources and sinks of CO2 in caves under mixed woodland and grassland vegetation

The sources and sinks of CO2 in caves under mixed woodland and grassland vegetation

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

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