HR: 11:20h
AN: PP22B-05 INVITED     [Abstracts]
TI: The Greenland Ice Core Chronology 2005 (GICC05)
AU: * Svensson, A
EM: as@gfy.ku.dk
AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AU: Andersen, K K
EM: kka@gfy.ku.dk
AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AU: Clausen, H B
PP22B-05 AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AU: Johnsen, S J
EM: sigfus@gfy.ku.dk
AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AU: Rasmussen, S O
EM: olander@gfy.ku.dk
AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AU: Steffensen, J P
EM: jps@gfy.ku.dk
AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AU: Vinther, B
PP22B-05 AF: University of Copenhagen, Niels Bohr Institute, Juliane Maries Vej 30, Copenhagen, 2100 Denmark
AB: A new Greenland Ice Core Chronology (GICC05) covering the last 41 kyr has been constructed from annual layer counting of high-resolution records from three Greenland ice cores. At any depth, the dating is based on the ice core with the best available high-resolution data, and the ice cores are tied together using unambiguous reference horizons, such as volcanic ash layers or major acidity spikes. Dating of the Holocene period back to 10 kyr b2k (before AD 2000) is based on new and published stable isotope measurements of the Dye-3 (GISP1) ice core, and on Electrical Conductivity Measurements (ECM) and Continuous Flow Analysis (CFA) of three chemical species in the GRIP ice core. Beyond 10 kyr b2k the time scale is based on records from the NorthGRIP ice core: CFA of 5 chemical species, dust and electrolytical conductivity, ECM, and the light intensity curve of the Visual Stratigraphy (VS). During cold glacial periods, where annual layers are thin, the counting is mostly based on VS, ECM and electrolytical conductivity, which have the highest resolution. A conservative uncertainty estimate of the time scale is obtained from identification of 'uncertain' annual layers, which are counted as 0.5±0.5 years. On average the uncertainty is <1% during the Holocene and ~5% in the glacial. The maximum counting error at 41 kyr b2k is 1600 years. The new time scale places the Holocene/Pleistocene transition at 11.7±0.1 kyr b2k, the onset of Greenland Interstadial 3 (GIS3) at 27.8±0.8 kyr b2k, and the onset of GIS8 at 38.3±1.4 kyr b2k. In the glacial period, GICC05 is generally in good agreement with both the GISP2 counted time scale of Meese and Sowers and with the NorthGRIP modelled time scale 'ss09sea'. On shorter time scales, however, there are significant discrepancies. In particular, we determine a strong correspondence between annual layer thickness and climate across the Greenland Interstadials, which is generally not found for the GISP2 time scale.
DE: 0724 Ice cores (4932)
DE: 1165 Sedimentary geochronology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005