Towards radiocarbon dating of ice cores

M Sigl,M Schwikowski,H.W Gäggeler,C Boutron,J Gabrieli,T Kellerhals,H.-A Synal,T.M Jenk,C Barbante,L Wacker,S Szidat

doi:10.3189/002214309790794922

Abstract

AbstractA recently developed dating method for glacier ice, based on the analysis of radiocarbon in carbonaceous aerosol particles, is thoroughly investigated. We discuss the potential of this method to achieve a reliable dating using examples from a mid- and a low-latitude ice core. Two series of samples from Colle Gnifetti (4450 m a.s.l., Swiss Alps) and Nevado Illimani (6300 m a.s.l., Bolivian Andes) demonstrate that the 14C ages deduced from the water-insoluble organic carbon fraction represent the age of the ice. Sample sizes ranged between 7 and 100 μg carbon. For validation we compare our results with those from independent dating. This new method is thought to have major implications for dating non-polar ice cores in the future, as it provides complementary age information for time periods not accessible with common dating techniques.

Highlights

Glaciers and ice sheets around the world contain information about a broad variety of environmental conditions during the Earth’s past
A recently developed new method to date ice cores using radiocarbon has proven to be a reliable tool for non-polar ice cores
For samples with low carbon content, precision and accuracy are strongly controlled by the required blank correction, giving the method low suitability for dating polar ice-core samples

Summary

Introduction

Glaciers and ice sheets around the world contain information about a broad variety of environmental conditions during the Earth’s past. In polar ice cores this can be achieved using a combination of annuallayer counting on seasonally varying parameters (e.g. d18O), matching signals to well-established chronologies and iceflow modelling (Meese and others, 1997; Vinther and others, 2006; Parrenin and others, 2007). Those techniques are, often inapplicable for high-alpine ice cores where glacier flow is dominated by the small-scale geometry of bedrock, resulting in a strongly non-linear depth–age relationship. These difficulties cannot be resolved fully using ice-flow models (Luthi and Funk, 2001). Suitable material included wood fragments or insects (Thompson and others, 1998, 2002, 2006b), it is emphasized that macrofossils in ice cores appear rather rarely

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