Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating

Regev, Lior; Eckmeier, Eileen; Mintz, Eugenia; Weiner, Steve

doi:10.1017/s0033822200034391

Cited by 24 publications

(14 citation statements)

References 35 publications

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“…Aeolian deposits of soot and dust from forest fires in the upland pine forests is possible, but these deposits were of similar age to the biomass that was conserved as peat. We cannot exclude the formation of calcite from oxalate (Regev et al, 2011), but we could not detect any calcite in our samples.…”

Section: Ash Contentmentioning

confidence: 61%

Carbon dynamics in boreal peatlands of the Yenisey region, western Siberia

et al. 2015

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Here we investigate the vegetation history and peat accumulation at the eastern boarder of the West Siberian plain, near the river Yenisey, south of permafrost. In this region peat started to accumulate 15 000 yr ago as gyttia of shallow lakes in ancient river valleys. This peat is older than previously reported mainly due to separating particulate organic carbon (POC) from dissolved organic carbon (DOC), which was 1900 to 6500 yr younger than POC. The probability to finding peat layers older than 12 000 yr is about 2 %. Peat accumulated as fen-peat at a constant rate of 0.2 mm yr−1 and 0.01 kg C m2 yr−1. The accumulation was higher in ancient river valley environments. Since 2000 yr these bogs changed into Sphagnum mires which accumulate up to about 0.1 kg C m2 yr−1 until present. The long-lasting fen stage, which makes the Yenisey bogs distinct from the West Siberian bogs is discussed as a consequence of the local hydrology. The high accumulation rate of peat in un-frozen mires is taken as an indication that thawing of permafrost peat may change northern peatlands also into long-lasting carbon sinks

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Section: Ash Contentmentioning

confidence: 61%

Carbon dynamics in boreal peatlands of the Yenisey region, western Siberia

et al. 2015

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“…Other fields that largely benefited from this analytical method are cultural heritage preservation and archaeology, and especially the study of anthropogenic carbonates. With grinding curves, it is possible to determine the formation process of unknown calcite crystals in sediments, artifacts and architectures, and to assess their state of preservation based on the degree of atomic order [28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

FTIR-Based Crystallinity Assessment of Aragonite–Calcite Mixtures in Archaeological Lime Binders Altered by Diagenesis

et al. 2019

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Lime plaster and mortar are pyrotechnological materials that have been employed in constructions since prehistoric times. They may nucleate as calcite and/or aragonite under different environmental settings. In nature, aragonite and calcite form through biogenic and geogenic processes that lead to different degrees of atomic order. The latter is a result of defects in the crystal lattice, which affect the properties of crystals, including their interaction with infrared light. Using Fourier transform infrared spectrometry (FTIR) with the KBr pellet method, it is possible to exploit these differences and assess the degree of atomic order of aragonite and calcite crystals and thus their mechanisms of formation. Here we use FTIR to characterize the degree of short-range atomic order of a pyrogenic form of aragonite recently observed in experimental and archaeological lime binders. We show that pyrogenic aragonite has a unique signature that allows its identification in archaeological sediments and lime binders of unknown origin. Based on these results, we developed a new FTIR-based method to assess the integrity and degree of preservation of aragonite and calcite when they occur together in the same material. This method allowed a better assessment of the diagenetic history of an archaeological plaster and finds application in the characterization of present-day conservation materials, such as lime plaster and mortar, where different polymorphs may nucleate and undergo recrystallization processes that can alter the mechanical properties of binders.

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“…However, the accuracy of the method is significantly limited by several carbonate contaminants, such as secondary calcite, to the point that presently a single approach to date any type of mortar is not available (Hajdas et al, 2017). Similar problems affect calcite in wood ash (e.g., Koumouzelis et al, 2001), although promising results have been obtained from well‐preserved crystals (Regev, Eckmeier, Mintz, Weiner, & Boaretto, 2011). Since aragonite is more soluble than calcite and does not precipitate out of bicarbonate, one could safely assume that if the pyrogenic form is found in sediments, then it is likely pristine (Boaretto, 2015; Toffolo & Boaretto, 2014).…”

Section: Archaeological Significancementioning

confidence: 95%

The significance of aragonite in the interpretation of the microscopic archaeological record

Toffolo

2020

Geoarchaeology

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Aragonite is one of the metastable polymorphs of calcium carbonate and is commonly found at archaeological sites in the form of mollusk shells and speleothems. Other occurrences include corals, fish otoliths, seed endocarps, wood ash, and lime plaster. These materials contain microscopic embedded information of fundamental importance for the assessment of the state of preservation of the archaeological record, the reconstruction of paleoenvironments, the identification of pyrotechnological processes, and the establishment of absolute chronologies. However, this information can be used only if the aragonite found at archaeological sites preserves its pristine structure and chemistry. Aragonite is metastable at ambient conditions and tends to dissolve and recrystallize into secondary aragonite or calcite, a process that entails the loss of its original elemental and isotopic signature. Therefore, well‐grounded archaeological interpretations depend on the correct identification of aragonite and the careful characterization of its basic properties. This article reviews the dissolution processes of different types of aragonite, the methods used for their identification, and the archaeological information that can be extracted. Particular emphasis is given to the discussion of key issues regarding absolute dating and postdepositional processes of archaeological sediments, and to a detailed overview of the recently observed pyrogenic aragonite.

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Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating

Cited by 24 publications

References 35 publications

Carbon dynamics in boreal peatlands of the Yenisey region, western Siberia

Carbon dynamics in boreal peatlands of the Yenisey region, western Siberia

FTIR-Based Crystallinity Assessment of Aragonite–Calcite Mixtures in Archaeological Lime Binders Altered by Diagenesis

The significance of aragonite in the interpretation of the microscopic archaeological record

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