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Poster De Conférence Année : 2023

A fast, non-destructive and low-cost dating approach of sediment cores over the last century

Résumé

Sediments from lakes and peat bogs are good archives to study changes that have occurred in the Earth system over the last century and older. However, developing such studies requires accurately dating the sediment accumulations. The common techniques are short-lived radionuclides (210Pb, 137Cs, and 241Am) for recent sediments and radiocarbon analyses for older sediments. However, these methods are relatively expensive and not fast to acquired. Consequently, they are not adapted when the aim is to work on a large set of sediment cores. This is particularly the case when the research objectives are to look at the representativity of a proxy based on a modern reference dataset. In palaeosciences, such modern references are frequently used for calibrations. These studies are often based on a collection of surface samples with the same thickness that may not cover the same time period depending on the sites due to various sedimentation rates. These temporal differences may lead to biases in the calibration studies.Here, we propose a fast, non-destructive and relatively cheap approach to provide a chronology that can be used to develop a referential or to help the sampling strategy and/or to improve/validate age-depth models based on classical analyses.Our protocol is based on known lead pollutions providing chronological markers for the last century and the Medieval and Roman periods. These lead pollutions can be observed by X-ray fluorescence core scanner analysis. Three markers can be identified for the last century: the lead peak before the oil crisis in 1973, the postWorld War 2 (1950) and end of Second Industrial Revolution in 1910 increases. Two older and less precisely dated peaks can be recorded, which correspond to the extraction and processing of ores during the Middle Ages and Roman period.In this poster, we present our approach applied to 23 lakes and 14 peat bogs; it has been independently validated on 6 different sites by short-lived radionuclides and radiocarbon dates. Although this approach was successfully applied in most cases, the results should be taken with caution and combined with the other established methods or chronological markers from historical events (earthquakes, floods, avalanches…).
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Dates et versions

hal-04306043 , version 1 (24-11-2023)

Identifiants

  • HAL Id : hal-04306043 , version 1

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Andréa Julien, Charline Giguet-Covex, Erwan Messager, Laurent Marquer, Anne-Lise Develle, et al.. A fast, non-destructive and low-cost dating approach of sediment cores over the last century. INQUA 2023, Jul 2023, Roma, Italy. . ⟨hal-04306043⟩
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