Radiocarbon dating of primary aragonite by sequential extraction of CO 2

Abstract

This paper describes the potential of correcting the ¹⁴C age shift resulting from the contamination of primary aragonites by detrital carbonates using online sequential extraction of CO₂. The experiments were carried out on laminated lacustrine aragonites collected from Holocene Dead Sea sediment sections. X-ray diffraction analysis revealed the presence of detrital calcite interpreted to originate from the watershed and transported to the lake with runoff. The contamination could not be separated physically from the sample, potentially contributing decayed ¹⁴C (‘dead carbon’) and increasing the age of the aragonite. Sequential extraction of successive fractions of CO₂ unveiled the effect of detrital material on the ¹⁴C ages, and showed that the first CO₂ extract represents the least contaminated ¹⁴C fraction that provides the best approximation for the true ¹⁴C age (which includes the lake’s reservoir age). We calculated the age offset contributed by the contamination range encountered in this study (1-21%) to be about 900 years per 10% contamination. The sequential extraction procedure is recommended for ¹⁴C dating of Holocene age lacustrine carbonates suspected to be contaminated with extraneous carbon-bearing materials.

Keywords

Radiocarbon dead carbon aragonite lacustrine carbonates Dead Sea

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References

Barkan, E. , Luz, B. and Lazar, B. 2001: Dynamics of the carbon dioxide system in the Dead Sea . Geochimica et Cosmochimica Acta 65, 355-368 .

Bookman (Ken-Tor), R. , Enzel, Y. , Agnon, A. and Stein, M. 2004: Late Holocene lake levels of the Dead Sea . GSA Bulletin 116, 555-571 .

Burr, G. S. , Edwards, R. L. , Donahue, D. J. , Druffel, E. R. M. and Taylor, F. W. 1992: Mass spectrometric 14C and U-Th measurements in coral . Radiocarbon 34, 611-618 .

Deevey, E. S., Jr , Gross, M. S. , Hutchinson, G. E. and Kraybill, H. L. 1954: The natural 14C contents of materials from hard-water lakes . Proceedings of the National Academy of Sciences of the USA, Washington 40, 285-288 .

Geyh, M. A. , Schotterer, U. and Grosjean, M. 1971: Temporal changes of the 14C reservoir effect in lakes . Radiocarbon 40, 921-931 .

Haase-Schramm, A. , Goldstein, S. L. and Stein, M. 2004: U-Th dating of Lake Lisan aragonite (late Pleistocene Dead Sea) and implications for glacial East Mediterranean climate change . Geochimica et Cosmochimica Acta 68, 985-1005 .

Haliva, A. 2004: Mineralogy, petrography and isotopic ratios of fine-grain detrital sediments of the Dead Sea group: Origin and transportation. M.Sc. Thesis, The Hebrew University of Jerusalem.

Heim, C. , Nowaczyk, N. R. , Negendank, F. W. , Leroy, S. A. G. and Ben-Avraham, Z. 1997: Near east desertification: evidence from the Dead Sea . Naturwissenschaften 84, 398-401 .

Heinemeier, J. , Jungner, H. , Lindroos, A. , Ringbom, å. , von Konow, T. and Rud, N. 1997: AMS 14C dating of lime mortar . Nuclear Instruments and Methods in Physics Research B 123, 487-495 .

10.

Katz, A. and Kolodny, N. 1989: Hypersaline brine diagenesis and evolution in the Dead Sea-Lake Lisan system (Israel) . Geochimica et Cosmochimica Acta 53, 59-67 .

11.

Katz, A. , Kolodny, Y. and Nissenbaum, A. 1977: The geochemical evolution of the Pleistocene Lake Lisan-Dead Sea system . Geochimica et Cosmochimica Acta 41, 1609-1626 .

12.

Kitagawa, H. and van der Plicht, J. 1998: Atmospheric radiocarbon calibration to 45000 y BP: Late glacial fluctuations and cosmogenic isotope production . Science 279, 1187-1190 .

13.

Kolodny, Y. , Stein, M. and Machlus, M. 2005: Sea-rain-lake relation in the Last Glacial East Mediterranean revealed by δ18O-d13C in Lake Lisan aragonites . Geochimica et Cosmochimica Acta 69, 4045-4060 .

14.

Olson, I. U. 1979: Radiocarbon dating of material from different reservoirs. In Suess, H. E. and Berger, R. , editors, Radiocarbon dating: proceedings of the ninth international conference, Los Angeles and La Jolla, 1976. University of California Press , 613-618.

15.

Schramm, A. , Stein, M. and Goldstein, S. L. 2000: Calibration of the 14C timescale to 50 kyr by 234U-230Th dating of sediments from Lake Lisan (the paleo-Dead Sea) . Earth and Planetary Science Letters 175, 27-40 .

16.

Slota, P. J., Jr , Jull, A. J. T. , Linick, T. W. and Toolin, L. J. 1987: Preparation of small samples for 14C accelerator targets by catalytic reduction of CO . Radiocarbon 29, 303-306 .

17.

Stein, M. , Migowski, C. , Bookman, R. and Lazar, B. 2004: Temporal changes in radiocarbon reservoir age in the Dead Sea lake Lisan system . Radiocarbon 46, 649-655 .

18.

Stein, M. , Starinsky, A. , Goldstein, S. L. , Katz, A. , Machlus, M. and Schramm, A. 1997: Strontium isotopic, chemical, and sedimentological evidence for the evolution of Lake Lisan and the Dead Sea . Geochimica et Cosmochimica Acta 61, 3975-3992 .

19.

Stiller, M. , Carmi, I. and Kaufman, A. 1988: Organic and inorganic 14C concentrations in the sediments of Lake Kinneret and the Dead Sea (Israel) and the factors which control them . Chemical Geology (Isotope Geoscience Section) 73, 63-78 .

20.

Vogel, J. C and Kronfeld, J. 1997: Calibration of radiocarbon dates for the late Pleistocene using U/Th dates on stalagmites . Radiocarbon 39, 27-32 .