HR: 1330h
AN: PP32A-0276    [PDF]
TI: New gas Measurements in the GRIP ice Core: Rapid Interglacial Climate Variability Ruled out and Proposal for a Reconstruction of the Last Interglacial in Greenland.
AU: Caillon, N
EM: caillon@lsce.saclay.cea.fr
AF: IPSL/LSCE, Orme des merisiers, Gif s Yvette, 91191 France
AU: * landais, a
EM: landais@lsce.saclay.cea.fr
AF: IPSL/LSCE, Orme des merisiers, Gif s Yvette, 91191 France
AU: chappellaz, j
EM: jerome@lgge.obs.ujf-grenoble.fr
AF: LGGE, 54 rue moliere, st martin d'heres, 83402 France
AU: Steffensen, J
EM: jps@gfy.ku.dk
AF: Dpt of Geophysics, Julianes Maries Vej 30, Copenhagen, 2100 Denmark
AU: delmotte, m
EM: delmotte@ipgp.jussieu.fr
AF: IPSL/LSCE, Orme des merisiers, Gif s Yvette, 91191 France
AU: jouzel, j
EM: jouzel@lsce.saclay.cea.fr
AF: IPSL/LSCE, Orme des merisiers, Gif s Yvette, 91191 France
AU: Masson-Delmotte, V
EM: masson@lsce.saclay.cea.fr
AF: IPSL/LSCE, Orme des merisiers, Gif s Yvette, 91191 France
AU: raynaud, d
EM: raynaud@lgge.obs.ujf-grenoble.fr
AF: LGGE, 54 rue moliere, st martin d'heres, 83402 France
AB: The disturbed stratigraphy of the ice in the lowest part (before 110 kyr BP) of the Greenland GRIP ice core has been demonstrated using gas measurements on a large depth scale. This is especially regretful since this period covers the previous interglacial corresponding to MIS 5e (130-120 kyr BP). Rapid isotopic variations on the scale of 20 cm are however experienced in the bottom of the GRIP ice-core with complicated chemical signatures that make them difficult to reconcile with disturbed stratigraphy of the ice. The d15N measurements associated with a simple modelling study lead to the solid conclusion that the most problematic of those rapid events (5e1) is not a climatic event. d18O of O2 is in agreement with a disturbed ice stratigraphy but recalls surprising features observed also on chemical data. Processes of diffusions after the mixing or even post-coring have to be involved to explain this profile; consequently we must place limits to the interpretation of some classical paleoclimatic proxies in small scale mixed ice. Despite these stratigraphy problems, we managed to propose a reconstruction of the disturbed GRIP chronology based on the succession of globally well mixed gas parameters. The GRIP d18Oice chronological sequence is obtained by comparing a new set of d18O of O2 and CH4 measurements from the bottom section of the GRIP core with their counterpart in the Vostok Antarctic profiles. This comparison clearly identifies ice from the penultimate glacial maximum (MIS 6: 190-130 kyr BP) in the GRIP core. Further it allows rough reconstruction of the last interglacial period and of the last glacial inception in Greenland.
DE: 1000 GEOCHEMISTRY (New field, replaces Rock Chemistry)
DE: 1040 Isotopic composition/chemistry
DE: 1827 Glaciology (1863)
DE: 3344 Paleoclimatology
DE: 3349 Polar meteorology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting