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EPICA-DOME C ICE CORE: EXTENDING THE DUST RECORD OVER THE LAST 7 CLIMATIC CYCLES (740 kyr B.P.)

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Citation:
Petit, J. .. R. , Delmonte, B. , Lambert, F. , Ruth, U. , Bigler, M. , Maggi, V. and Stefensen, J. P. (2004): EPICA-DOME C ICE CORE: EXTENDING THE DUST RECORD OVER THE LAST 7 CLIMATIC CYCLES (740 kyr B.P.) , SCAR Open Science Conference, 25-31.07.2004, Bremen, Germany. .
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Abstract:

Objectives:The European Project of Ice Coring in Antarctica (EPICA) gathers 10 nations and aims to reconstruct pastclimate and environment from deep ice cores in Antarctica to document the last part of the Quaternaryperiod. Two deep ice cores are planned in two different regions : one in the Dome C area (75°06' S, 123°21'E, 3233m a.s.l.) in central area, the second in Droning Maud area (75°00'S; 00°04'E, 2892 m.a.s.l)closer to Southern Atlantic ocean. The first drilling from Dome C reached 3200 m depth by January 2003and the dust record over 3130m is presented here.Material and Methods:Insoluble dust in Antarctic ice mainly originates from southern South America and results from eoliandeflation of the continent, transported by the atmospheric circulation.Dust measurements have been performed using two independent techniques. A laser system was deployedon the field for continuous measurements and set on the continuous flow line sampler along with thechemistry analysis. The signal was recorded continuously from 769 m depth down to 3137m and could belinked to the total dust concentration. On a other hand, from 1000 levels of discrete ice core samples, thedust concentrations and size distributions have been performed in laboratory using a Coulter Coulter#(mutisizerII).Results:During glacial periods, a large change of dust concentration is commonly observed on ice core fromAntarctica and Greenland and interpreted as the consequence of the glacial climate with a great extensionof the ice caps, periglacial area, a bigger continental aridity and reduced hydrological cycle and vegetationcover, change in the atmospheric circulation # At the first order, the dust concentration in Antarctic ice corescould be linked to the global ice volume.Over the last 4 climate cycles, the EPICA Dome C dust record mimics the Vostok dust record and the highdust inputs (up to a factor 50 with respect to present time) are linked to the glacial periods and to MarineIsotopic Stage (i.e. MIS 2, 4, 6, 10). For glacial and interglacial periods, dust flux appear very similar on thetwo sites and may be representative for a large geographic area. Several dust events provide confidentstratigraphic markers for linking the two ice cores.EPICA Dome C dust record extends the climatic record beyond the 4 Vostok climatic cycles and 3 morecycles can be recognized. Assigning the high (low) concentration to glacial (interglacial) period, EPICAreveals a record extending back to the end the Marine Isotopic Stage 18 (740 ka BP) at 3130 m depth.Conclusions:The EPICA dust record is compared to the record of the ice volume (Bassinot et al. 1994) and to themagnetic record of the Chinese loess record (Kukla et al, 1990) and it reveals several common patternsand the succession of global glaciations during the end of Quaternary. Completion of the ice core studiesalong with information from stable isotopes, ice chemistry, green house gases# will offer a climate record ofnearly one million years.

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