DOI: 10.1594/pangaea.984828
title: Match points EGRIP-NGRIP1 used for the chronology transfer for the East GReenland Ice-core Project (EGRIP), extended to 108,305 years before 2000 CE

description: This data file provides the chronology (named GICC05-EGRIP-1) for the deep ice core from the East GReenland Ice-core Project (EGRIP) down to 108,305 years before 2000 CE. We rely mainly on volcanic events and common patterns of peaks in dielectric profiling (DEP), electrical conductivity measurements (ECM) and tephra records for the synchronization between the EGRIP, NEEM and NGRIP ice cores in Greenland. We transfer the annual-layer-counted Greenland Ice Core Chronology 2005 (GICC05) timescale from the NGRIP core to the EGRIP ice core by means of these match points. This data file extends earlier chronologies.
description: The part younger than 15 ka b2k was presented in the Mojtabavi et al. (2020) paper. The 15-49.9 ka b2k part was presented in the Gerber et al. (2021) paper. The part older than 49.9 ka b2k is presented in the accompanying paper by Stoll et al. (2025).Please state the full time scale name GICC05-EGRIP-1 at least once in data files and work based on this time scale. Use the short labels GICC05 on graphs etc. only if there is no risk of confusion with other time scales.EGRIP depths have been transferred to NGRIP by linear interpolation between match points, from which GICC05 ages were obtained using the NGRIP (depth, age) relation. Above the most shallow match point (EGRIP depth 21.349 m), we use annual layer counting from the following paper: Sinnl et al. (2022).All ages are given in whole years b2k (years before A.D. 2000).The NGRIP1 core reaches down to a depth of 1372 m. The NGRIP2 core (drilled 20 meters away from the NGRIP1 core) reaches from surface to bedrock, but high-resolution measurements apart from DEP have only been carried out downwards from 1346 m. In the 26 m overlap zone, the cores are offset by 0.43 m on average, probably due to uncertainties in the logging procedure (see Hvidberg et al., 2002). Thus, the same features appear at larger depths in the NGRIP1 than in the NGRIP2 core. Here, we derive the EGRIP time scale from the match points between EGRIP and NGRIP1 until 9810 a b2k and the match points between EGRIP and NGRIP2 below this.The GICC05 chronology extends to 60.2 ka b2k, and has been published in several stages. The relevant references here are:• Main Holocene part: Vinther et al. (2006).• Late glacial / Early Holocene part: Rasmussen et al. (2006).• 16-42 ka part: Andersen et al. (2006).• 42-60 ka part: Svensson et al. (2008).The value "MCE" is the Maximum Counting Error of the GICC05 time scale. See Rasmussen et al. (2006) for a full description.In a standard deviation context, the maximum counting error should be regarded as 2 sigma as discussed in Andersen et al. (2006).Below 60.2 ka b2k, the GICC05modelext time scale has been used. This part of the time scale is based on ice-flow modelling: Wolff et al. (2010).There is no MCE estimate for the modelled part of the time scale.The counting error does not include uncertainty contributions from the time scale transfer. Most match points are accurate to 10 cm or better (i.e. a few years except in the deeper parts).The time scale transfer involves interpolation over relatively long sections resulting in significant relative uncertainty.Synchronization above 15 ka b2k carried out by S. Mojtabavi, G. Sinnl, M.S. Jensen and S.O. Rasmussen. Synchronization in the 15-49.9 ka b2k interval carried out by G. Sinnl, T.A. Gerber and S.O. Rasmussen. Synchronization below 49.9 ka b2k carried out by G. Sinnl and S.O. Rasmussen.