Methodological approaches to determining the marine radiocarbon reservoir effect

Ascough, P.L., Cook, G.T. and Dugmore, A. (2005) Methodological approaches to determining the marine radiocarbon reservoir effect. Progress in Physical Geography, 29(4), pp. 532-547. (doi:10.1191/0309133305pp461ra)

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Publisher's URL: http://dx.doi.org/10.1191/0309133305pp461ra

Abstract

The marine radiocarbon reservoir effect is an offset in 14C age between contemporaneous organisms from the terrestrial environment and organisms that derive their carbon from the marine environment. Quantification of this effect is of crucial importance for correct calibration of the <sup>14</sup>C ages of marine-influenced samples to the calendrical timescale. This is fundamental to the construction of archaeological and palaeoenvironmental chronologies when such samples are employed in <sup>14</sup>C analysis. Quantitative measurements of temporal variations in regional marine reservoir ages also have the potential to be used as a measure of process changes within Earth surface systems, due to their link with climatic and oceanic changes. The various approaches to quantification of the marine radiocarbon reservoir effect are assessed, focusing particularly on the North Atlantic Ocean. Currently, the global average marine reservoir age of surface waters, R(t), is c. 400 radiocarbon years; however, regional values deviate from this as a function of climate and oceanic circulation systems. These local deviations from R(t) are expressed as +R values. Hence, polar waters exhibit greater reservoir ages (δR = c. +400 to +800 <sup>14</sup>C y) than equatorial waters (δR = c. 0 <sup>14</sup>C y). Observed temporal variations in δR appear to reflect climatic and oceanographic changes. We assess three approaches to quantification of marine reservoir effects using known age samples (from museum collections), tephra isochrones (present onshore/offshore) and paired marine/terrestrial samples (from the same context in, for example, archaeological sites). The strengths and limitations of these approaches are evaluated using examples from the North Atlantic region. It is proposed that, with a suitable protocol, accelerator mass spectrometry (AMS) measurements on paired, short-lived, single entity marine and terrestrial samples from archaeological deposits is the most promising approach to constraining changes over at least the last 5 ky BP.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ascough, Dr Philippa and Cook, Professor Gordon
Authors: Ascough, P.L., Cook, G.T., and Dugmore, A.
Subjects:G Geography. Anthropology. Recreation > GB Physical geography
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Progress in Physical Geography
ISSN:0309-1333
Copyright Holders:Copyright © 2005 SAGE Publications
First Published:First published in Progress in Physical Geography 29(4):532-547
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher.

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