A ¹⁰Be production‐rate calibration for the Arctic

Abstract

We present a Baffin Bay 10 Be production-rate calibration derived from glacial deposits in western Greenland and Baffin Island, and test our results against published 10 Be calibration datasets to develop an Arctic 10 Be production rate. Our calibration comprises: (i) 10 Be measurements from moraine boulders linked to a 14 Cdated moraine at Jakobshavn Isfjord in western Greenland, (ii) an independent and previously published 10 Be production rate at Jakobshavn Isfjord and (iii) re-measured 10 Be concentrations from a Baffin Island calibration site that is included in the north-eastern North America dataset. Combined, we calculate a sea-level/high-latitude 10 Be production rate for the Baffin Bay region of 3.96 AE 0.07 atoms g À1 a À1 (Lal/Stone scaling model). After testing the Baffin Bay rate against calibration sites in Norway and north-eastern North America, we calculate a more conservative Arctic production rate of 3.96 AE 0.15 atoms g À1 a À1 . The Baffin Bay and Arctic 10 Be production rates are indistinguishable from the north-eastern North America 10 Be production rate (3.91 AE 0.19 atoms g À1 a À1 ) and yield overall uncertainties of <2-3.7% (1s). These production rates reduce systematic uncertainties in 10 Be-based chronologies of ice-margin change and allow 10 Be-based chronologies to be more confidently compared with high-resolution climate records, such as those from Greenland ice cores.

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…Several recent 10 Be production rate calibration studies have reported 5-15% lower reference 10 Be production rates (e.g. Balco et al, 2009;Young et al, 2013;Heyman, 2014) compared to the original CRONUS production rates (e.g. Balco et al, 2008), implying that many exposure ages are likely to be thousands of years older than previously reported.…”

“…Several recent studies have focussed on constraining the extent and thickness of extant ice sheets in Greenland (Roberts et al, 2008;Briner et al, 2014;Young et al, 2013) and Antarctica (Stone et al, 2003;Bentley et al, 2010;Mackintosh et al, 2011) since the LGM.…”

Rapid last-deglacial thinning and retreat of the marine-terminating southwestern Greenland ice sheet

“…We use the Arctic sea-level 220 high-latitude 10 Be production rate of 3.93 ± 0.15 atoms g -1 yr -1 (Young et al, 2013b). 221…”

Holocene Chronology of the Brattforsheden Delta and Inland Dune Field, Sw Sweden

“…Measured 10 Be concentrations were used to calculate surface exposure ages using the CRONUS-Earth 10 Be-26 Al exposure age calculator version 2.2 (http://hess.ess.washington.edu), assuming no prior exposure and no erosion during exposure. The calculator provides a variety of production rate calibrations, and we used the Arctic calibration (Young et al, 2013) with a spallation-induced production rate of 3.93 ± 0.15 atoms g -1 a -1 (CRONUS-Earth 2013; Alternate calibration data sets, Wrapper script 2.2, Main calculator 2.1, constants 2.2.1, muons 1.1). This production rate was chosen because the calibration data set extends back to ca.…”

“…Lake Falltjärnen has a threshold level at 160-165 m a.s.l. (Chmeleff et al, 2010;Korschinek et al, 2010), and the Arctic calibration data set (Young et al, 2013 …”