Natural Abundance of Carbon Isotopes (14C, 13C) in Lichens and Calcium Oxalate Pruina: Implications for Archaeological and Paleoenvironmental Studies
Issue Date
2002-01-01Keywords
lichensArkansas
sandstone
Marion County Arkansas
Val Verde County Texas
calcium
oxalates
paleoenvironment
accelerator mass spectra
Texas
clastic rocks
statistical analysis
mass spectra
spectra
archaeology
isotope ratios
Holocene
upper Holocene
alkaline earth metals
metals
United States
Cenozoic
Quaternary
C 14
carbon
isotopes
radioactive isotopes
C 13 C 12
stable isotopes
absolute age
sedimentary rocks
carbonate rocks
limestone
Metadata
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Beazley, M. J., Rickman, R. D., Ingram, D. K., Boutton, T. W., & Russ, J. (2002). Natural abundances of carbon isotopes (14C, 13C) in lichens and calcium oxalate pruina: Implications for archaeological and paleoenvironmental studies. Radiocarbon, 44(3), 676-683.Journal
RadiocarbonAdditional Links
http://radiocarbon.webhost.uits.arizona.edu/Abstract
Radiocarbon ages of calcium oxalate that occurs naturally on rock surfaces have been used recently in archaeological and paleoenvironmental studies. Oxalate rock coatings are found globally, with most appearing to be residues from epilithic lichens. To explore the source(s) of carbon used by these organisms for the production of oxalate we measured the natural abundances of 14C and 13C in 5 oxalate-producing lichen species, 3 growing on limestone in southwestern Texas and 2 on sandstone in Arkansas. We also examined the distribution of the isotopes between the calcium oxalate and lichen tissues by separating these components and measuring the 13C/C independently. The results demonstrate that the limestone species were slightly enriched in 14C, by 1.7 per mil, relative to the sandstone species, which suggests that "dead" carbon from the limestone substrate does not constitute a significant source of carbon for the production of oxalate. The calcium oxalate produced by the lichens is also enriched in 13C by 6.5 per mil compared to the lichen tissues, demonstrating that there is a large carbon isotope discrimination during oxalate biosynthesis. These results support the reliability of 14C ages of calcium oxalate rock coatings used for archaeological and paleoclimate studies.Type
Articletext
Language
enISSN
0033-8222ae974a485f413a2113503eed53cd6c53
10.1017/S0033822200032124