Section 71
Chapter 70,705

C-14 Dating of Soil Organic Carbon (Soc) in Loess-Paleosol using Sequential Pyrolysis and Accelerator Mass Spectrometry (Ams)

Cheng, P.; Zhou, W.; Wang, H.; Lu, X.; Du, H.

Radiocarbon 55(2-3): 563-570


ISSN/ISBN: 0033-8222
DOI: 10.1017/s0033822200057696
Accession: 070704370

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The chemical extraction of soil organic carbon (SOC) fractions from soils often does not produce satisfactory results for radiocarbon dating. In this study, a sequential pyrolysis technique was investigated. The soil was pyrolyzed at temperatures of 200, 400, 600, and 800 degrees C to partition organic carbon into pyrolytic volatile (Py-V) and pyrolytic residue (Py-R) fractions. The preliminary results show that the C-14 dates of both fractions become progressively older as the pyrolysis temperature is increased. In addition, the ages of the Py-V fractions are consistently younger than the corresponding Py-R fractions extracted at the same temperature. Experimental results of known-age paleosol samples indicate that the Py-V fractions obtained between 600 and 800 degrees C yield the most reliable ages. This technique provides a new approach to improve the accuracy of C-14 dating of loess-paleosol sequences.

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