Reservoirs and radiocarbon: ¹⁴C dating problems in Myvatnssveit, Northern Iceland

Ascough, P.L. , Cook, G.T., Church, M.J., Dugmore, A.J., McGovern, T.G., Dunbar, E. , Einarsson, E., Frioriksson, A. and Gestsdottir, H. (2007) Reservoirs and radiocarbon: ¹⁴C dating problems in Myvatnssveit, Northern Iceland. Radiocarbon, 49(2), pp. 947-961.

Abstract

This paper examines 2 potential sources of the radiocarbon offset between human and terrestrial mammal (horse) bones recovered from Norse (~AD 870–1000) pagan graves in Mývatnssveit, north Iceland. These are the marine and freshwater ¹⁴C reservoir effects that may be incorporated into human bones from dietary sources. The size of the marine ¹⁴C reservoir effect (MRE) during the Norse period was investigated by measurement of multiple paired samples (terrestrial mammal and marine mollusk shell) at 2 archaeological sites in Mývatnssveit and 1 site on the north Icelandic coast. These produced 3 new ΔR values for the north coast of Iceland, indicating a ΔR of 106 ± 10 ¹⁴C yr at AD 868–985, and of 144 ± 28 14C yr at AD 1280–1400. These values are statistically comparable and give an overall weighted mean ΔR of 111 ± 10 ¹⁴C yr. The freshwater reservoir effect was similarly quantified using freshwater fish bones from a site in Mývatnssveit. These show an offset of between 1285 and 1830 ¹⁴C yr, where the fish are depleted in ¹⁴C relative to the terrestrial mammals. This is attributed to the input of geothermally derived CO₂ into the groundwater and subsequently into Lake Mývatn. We conclude the following: i) some of the Norse inhabitants of Mývatnssveit incorporated non-terrestrial resources into their diet that may be identified from the stable isotope composition of their bone collagen; ii) the MRE off the north Icelandic coast during the Norse period fits a spatial gradient of wider North Atlantic MRE values with increasing values to the northwest; and iii) it is important to consider the effect that geothermal activity could have on the ¹⁴C activity of samples influenced by groundwater at Icelandic archaeological sites.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ascough, Dr Philippa and Dunbar, Dr Elaine and Cook, Professor Gordon
• Authors: Ascough, P.L., Cook, G.T., Church, M.J., Dugmore, A.J., McGovern, T.G., Dunbar, E., Einarsson, E., Frioriksson, A., and Gestsdottir, H.
• Subjects: Q Science > QE Geology; G Geography. Anthropology. Recreation > GE Environmental Sciences
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Radiocarbon
• ISSN: 0033-8222
• Copyright Holders: Copyright © 2007 University of Arizona Press
• First Published: First published in Radiocarbon 49(2):947-961
• Publisher Policy: Reproduced with the permission of the publisher.