An improved north–south synchronization of ice core records around the 41 kyr &amp;lt;sup&amp;gt;10&amp;lt;/sup&amp;gt;Be peak

Grant M Raisbeck,Anders Svensson,Jorgen P Steffensen,Hans-Arno Synal,Françoise Yiou,Alexandre Cauquoin,Amaelle Landais,Vladimir Y Lipenkov,Sigfus J Johnsen,Hans Oerter,Jean Jouzel,Juerg Beer,Jean-Robert Petit

doi:10.5194/cp-13-217-2017

Abstract

Abstract. Using new high-resolution 10Be measurements in the NGRIP, EDML and Vostok ice cores, together with previously published data from EDC, we present an improved synchronization between Greenland and Antarctic ice cores during the Laschamp geomagnetic excursion ∼ 41 kyr ago. We estimate the precision of this synchronization to be ±20 years, an order of magnitude better than previous work. We discuss the implications of this new synchronization for making improved estimates of the depth difference between ice and enclosed gas of the same age (Δdepth), difference between age of ice and enclosed gas at the same depth (Δage) in the EDC and EDML ice cores, spectral properties of the 10Be profiles and phasing between Dansgaard–Oeschger-10 (in NGRIP) and AIM-10 (in EDML and EDC).

Highlights

In a previous study, Raisbeck et al (2007) synchronized the Greenland GRIP and Antarctic EPICA Dome C (EDC) ice cores using the structured peak of cosmogenic 10Be resulting from a combination of the low geomagnetic intensity and variable solar activity during the Laschamp geomagnetic excursion ∼ 41 kyr ago (Lascu et al, 2016, and references therein)
Using new high-resolution 10Be measurements in the NGRIP, EPICA Dronning Maud Land (EDML) and Vostok ice cores, together with previously published data from EDC, we present an improved synchronization between Greenland and Antarctic ice cores during the Laschamp geomagnetic excursion ∼ 41 kyr ago
As previously noted (Yiou et al, 1997; Raisbeck et al, 2007) all cores show a highly structured peak of 10Be centered on Antarctic isotopic maxima (AIM)-10 (EDC, EDML, Vostok) or DO-10 (NGRIP)

Summary

Introduction

In a previous study, Raisbeck et al (2007) synchronized the Greenland GRIP and Antarctic EPICA Dome C (EDC) ice cores using the structured peak of cosmogenic 10Be resulting from a combination of the low geomagnetic intensity and variable solar activity during the Laschamp geomagnetic excursion ∼ 41 kyr ago (Lascu et al, 2016, and references therein). The estimated precision of this synchronization was 200 years, due mainly to uncertainties associated with the GRIP 10Be record (sample time resolution of 25–50 years, corrections for loss of 10Be on 0.4 μm filters for some samples, and several missing samples) We improve this situation significantly here by using a much higher resolution (5–10 years) 10Be profile in the NGRIP ice core. Maps showing the locations and a brief description of drilling operations for the ice cores studied here can be found in Jouzel (2013) With these improvements, we estimate the uncertainty on the synchronization to be ±20 years at our new tie points, and ±35 years over the whole Laschamp event. Raisbeck et al.: An improved north–south synchronization of ice core records

Methods

Results

Spectral properties of the 10Be profiles

Implications for bipolar seesaw and stable isotope interpretation

Conclusion