An optimized multi-proxy, multi-site Antarctic ice and gas orbital chronology (AICC2012): 120–800 ka

Abstract

Abstract. An accurate and coherent chronological framework is essential for the interpretation of climatic and environmental records obtained from deep polar ice cores. Until now, one common ice core age scale had been developed based on an inverse dating method (Datice), combining glaciological modelling with absolute and stratigraphic markers between 4 ice cores covering the last 50 ka (thousands of years before present) (Lemieux-Dudon et al., 2010). In this paper, together with the companion paper of Veres et al. (2013), we present an extension of this work back to 800 ka for the NGRIP, TALDICE, EDML, Vostok and EDC ice cores using an improved version of the Datice tool. The AICC2012 (Antarctic Ice Core Chronology 2012) chronology includes numerous new gas and ice stratigraphic links as well as improved evaluation of background and associated variance scenarios. This paper concentrates on the long timescales between 120–800 ka. In this framework, new measurements of δ18Oatm over Marine Isotope Stage (MIS) 11–12 on EDC and a complete δ18Oatm record of the TALDICE ice cores permit us to derive additional orbital gas age constraints. The coherency of the different orbitally deduced ages (from δ18Oatm, δO2/N2 and air content) has been verified before implementation in AICC2012. The new chronology is now independent of other archives and shows only small differences, most of the time within the original uncertainty range calculated by Datice, when compared with the previous ice core reference age scale EDC3, the Dome F chronology, or using a comparison between speleothems and methane. For instance, the largest deviation between AICC2012 and EDC3 (5.4 ka) is obtained around MIS 12. Despite significant modifications of the chronological constraints around MIS 5, now independent of speleothem records in AICC2012, the date of Termination II is very close to the EDC3 one.

Annual proxy data from Lago Grande di Monticchio (southern Italy) between 76 and 112 ka: new chronological constraints and insights on abrupt climatic oscillations

“…The new annual sedimentological data in combination with the previously published pollen record and the independently established chronology allows detailed high-resolutioncomparison of the MON (40 • N) sediment record along a NW-SE transect across western Europe including the high-resolution δ 18 O calcite NALPS stalagmite (Boch et al, 2011) from the Austrian Alps (47 • N) and δ 18 O ice NorthGRIP ice core (75 • N) in order to investigate similarities and differences between these key climate archives (Fig. 7).…”

“…Therefore, the abrupt climate changes during the early last glacial period (MIS 5d-a) have been less understood than the rapid events within the full glacial conditions (MIS 3). Besides the δ 18 O ice NorthGRIP ice core record, the U/Th-dated δ 18 O calcite speleothem record in the Northern Alps (NALPS) (Boch et al, 2011) provides a temperature-sensitive proxy record with resolution higher than 20 years and comparable to the NorthGRIP ice core. These two high-resolution archives show similar climate variability and reveal rapid temperature changes superimposed onto the millennial-scale variability (Capron et al, 2010;Boch et al, 2011).…”

“…Besides the δ 18 O ice NorthGRIP ice core record, the U/Th-dated δ 18 O calcite speleothem record in the Northern Alps (NALPS) (Boch et al, 2011) provides a temperature-sensitive proxy record with resolution higher than 20 years and comparable to the NorthGRIP ice core. These two high-resolution archives show similar climate variability and reveal rapid temperature changes superimposed onto the millennial-scale variability (Capron et al, 2010;Boch et al, 2011). However, a detailed discussion about regional synchronicity is still hampered by the large dating uncertainty due to limitations in the chronologies.…”

Iron Fertilization of the Subantarctic Ocean During the Last Ice Age

“…The high-resolution XRF Fe concentration records from ODP Site 1090 and TN57-06 were used to align the two cores using the software Analyseries (46). The good correlation of the two records after the alignment allows us to directly compare the measurements performed in the two cores with minimal stratigraphic uncertainty ( The age model of our record was generated by graphic correlation of the highresolution 230 Th-normalized Fe flux from ODP Site 1090 to the most recent ice core dust reconstruction from EPICA Dome C (44), using ice core chronology (AICC2012) (47,48) (Fig. S2).…”

“…S1a). This indicates that the 230 Th measurements performed in can be used to reconstruct sedimentary fluxes of different elements and/or organic compounds in both records.For example, in Figure S1c, the high-resolution 230 Th-normalized mass flux (Fig.S1b) was used to calculate iron fluxes both in ODP Site 1090 and TN057-6 ( The age model of our record was generated by graphic correlation of the highresolution 230 Th-normalized Fe flux from ODP Site 1090 to the most recent ice core dust reconstruction from EPICA Dome C (44), using ice core chronology (AICC2012) (47,48) (Fig. S2).…”