Palaeoclimatic and geomorphic implications of 230Th/234U dates on speleothems from Britain

Atkinson, T. C.; Harmon, Russell S.; Smart, Peter L.; Waltham, A. C.

doi:10.1038/272024a0

Cited by 84 publications

(35 citation statements)

References 14 publications

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“…Atkinson et al, 1978), and the generation of oxygen isotope time series in an attempt to elucidate palaeotemperatures (Gascoyne, 1992). In the latter case, the attraction was the useful property of cave interiors to be close to the mean annual external temperature.…”

Section: The Progress Of Speleothem Studies and The Future Agendamentioning

confidence: 99%

Modification and preservation of environmental signals in speleothems

Fairchild

Smith

Baker

et al. 2006

Earth-Science Reviews

739

506

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Speleothems are primarily studied in order to generate archives of climatic change and results have led to significant advances in identifying and dating major shifts in the climate system. However, the climatological meaning of many speleothem records cannot be interpreted unequivocally; this is particularly so for more subtle shifts and shorter time periods, but the use of multiple proxies and improving understanding of formation mechanisms offers a clear way forward.An explicit description of speleothem records as time series draws attention to the nature and importance of the signal filtering processes by which the weather, the seasons and longer-term climatic and other environmental fluctuations become encoded in speleothems. We distinguish five sources of variation that influence speleothem geochemistry: atmospheric, vegetation/soil, karstic aquifer, primary speleothem crystal growth and secondary alteration and give specific examples of their influence. The direct role of climate diminishes progressively through these five factors.We identify and review a number of processes identified in recent and current work that bear significantly on the conventional interpretation of speleothem records, for example: 1) speleothem geochemistry can vary seasonally and hence a research need is to establish the proportion of growth attributable to different seasons and whether this varies over time.2) whereas there has traditionally been a focus on monthly mean δ 18 O data of atmospheric moisture, current work emphasizes the importance of understanding the synoptic processes that lead to characteristic isotope signals, since changing relative abundance of different weather types might 1 Corresponding author, fax +44(0)1214145528, E-mail: i.j.fairchild@bham.ac.uk control their variation on the longer-term. 3) the ecosystem and soil zone overlying the cave fundamentally imprint the carbon and trace element signals and can show characteristic variations with time. 4) new modelling on aquifer plumbing allows quantification of the effects of aquifer mixing. 5) recent work has emphasized the importance and seasonal variability of CO 2 -degassing leading to calcite precipitation upflow of a depositional site on carbon isotope and trace element composition of speleothems. 6) Although much is known about the chemical partitioning between water and stalagmites, variability in relation to crystal growth mechanisms and kinetics is a research frontier. 7) Aragonite is susceptible to conversion to calcite with major loss of chemical information, but the controls on the rate of this process are obscure.Analytical factors are critical to generate high-resolution speleothem records. A variety of methods of trace element analysis are available, but standardization is a common problem with the most rapid methods. New stable isotope data on Irish stalagmite CC3 compares rapid laser-ablation techniques with the conventional analysis of micromilled powders and ion microprobe methods. A high degree of comparability between techniques ...

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Section: The Progress Of Speleothem Studies and The Future Agendamentioning

confidence: 99%

Modification and preservation of environmental signals in speleothems

Fairchild

Smith

Baker

et al. 2006

Earth-Science Reviews

739

506

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“…They grow mainly under wet and warm environmental conditions. Oxygen isotopic composition of speleothems together with radiometric dating techniques have been used for the reconstruction of past precipitation and temperature patterns, mainly for glacial periods [93][94][95][96][97][98][99]. One of the important assumptions in using speleothem ␦ 18 O to reconstruct climate is that inside the cave a relative humidity of 100% persisted during precipitation of the carbonate.…”

Section: Reconstruction Of Carbon Isotopic Composition Of Atmosphericmentioning

confidence: 99%

Stable isotope ratio mass spectrometry in global climate change research

Ghosh

Brand

2003

International Journal of Mass Spectrometry

114

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Stable isotope ratios of the life science elements carbon, hydrogen, oxygen and nitrogen vary slightly, but significantly in major compartments of the earth. Owing mainly to antropogenic activities including land use change and fossil fuel burning, the 13 C/ 12 C ratio of CO 2 in the atmosphere has changed over the last 200 years by 1.5 parts per thousand (from about 0.0111073 to 0.0110906). In between interglacial warm periods and glacial maxima, the 18 O/ 16 O ratio of precipitation in Greenland has changed by as much as 5 parts per thousand (0.001935-0.001925). While seeming small, such changes are detectable reliably with specialised mass spectrometric techniques. The small changes reflect natural fractionation processes that have left their signature in natural archives. These enable us to investigate the climate of past times in order to understand how the Earth's climatic system works and how it can react to external forcing. In addition, studying contemporary isotopic change of natural compartments can help to identify sources and sinks for atmospheric trace gases provided the respective isotopic signatures are large enough for measurement and have not been obscured by unknown processes. This information is vital within the framework of the Kyoto process for controlling CO 2 emissions.

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“…The 230TW2MU method has been particularly useful in determining ages of late Quaternary carbonate formations (Ku 1976;Schwarcz 1980;Hennig, Grun and Brunnacker 1983;Mahaney 1984;Latham and Schwarcz 1992;Fontes et al 1992). In the case of relatively pure CaCO3 deposits such as coral reefs and speleothems, results are often definitive (Atkinson and Harmon 1978;Harmon et al 1975;Harmon, Ford and Schwarcz 1977;Harmon, Schwarcz and Ford 1977). Travertines are also suitable subjects for dating, but must be sampled and analyzed carefully, because of their porous structures and occasional impurities (Schwarcz et a1.1979;Harmon, Glazek and Nowak 1980;Hennig, Bangert and Herr 1980;Hennig, Grun and Brunnacker 1983;Blackwell and Schwarcz 1986;Kronfeld et al 1988;Baskaran, Rajagopalan and Somayaj ulu 1989;Schwarcz and Latham 1989;Szabo 1990;Bischoff and Fitzpatrick 1991).…”

Section: Uranium-series Dating Of Plitvice Travertinesmentioning

confidence: 99%

Radiocarbon and Uranium-Series Dating of the Plitvice Lakes Travertines

et al. 1994

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ABSTRACT. Radiocarbon and uranium-series ages of the calcareous deposits of the Plitvice Lakes show that travertines were deposited during three warm, humid, interglacial oxygen isotope stages. According to our measurements, only calcite crystals or crystal aggregates represent reliable material for both 230Th/234U and 234U/'8U dating. Compact old travertine in the form of sandstone is less reliable; it can be dated by both methods provided that its detrital contamination is not significant, demonstrated by very low 14C activity (<1.5-2.0 pMC) and a high 230Th/232Th ratio. Old porous travertine contaminated with recent carbonates and Th-bearing clay (pMC > 5, 23°Th/232Th < 5) gives erroneous results by both methods. Stage 1(Holocene) deposition is shown primarily by 14C dating corroborated by sedimentological and palynologic studies as well as by both 230Th/ 234U and 234U/238U disequilibrium methods. The intensive growth of travertine barriers coincided with significant climate warming in the Holocene. Stage 5 deposition is confirmed by the 23oTh/234U dating of crystalline calcite aggregates embedded in the travertine matrix and by concordant 230Th/ 234U and 234U/ 238U ages, assuming that the 234U/ 238U activity ratio of 1.88 observed in modern streams and in Holocene deposits can be extended to past epochs. The travertine deposition period was very short, peaking Ca. 120 ± 10 ka BP. Stage 11 deposition is indicated by 234U/238U dating only, the period being within the 234U decay range, but not that of 230Th. Stage 11 travertine was deposited ca. 420 ± 50 ka BP. We did not find travertine samples with U-series ages indicating a growth period during relatively warm Stages 7 and 9; due to the scarcity of old travertine outcrops, these and possibly other stages cannot be excluded on the basis of presented data. All of these isotopic dating results concur with the field relation of the travertine complex of the Plitvice Lakes.

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Palaeoclimatic and geomorphic implications of 230Th/234U dates on speleothems from Britain

Cited by 84 publications

References 14 publications

Modification and preservation of environmental signals in speleothems

Modification and preservation of environmental signals in speleothems

Stable isotope ratio mass spectrometry in global climate change research

Radiocarbon and Uranium-Series Dating of the Plitvice Lakes Travertines

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