Investigation of a deep ice core from the Elbrus western plateau, the Caucasus, Russia

• Main Authors: Mikhalenko, V., Sokratov, S., Kutuzov, S., /Ginot, Patrick, Legrand, M., Preunkert, S., Lavrentiev, I., Kozachek, A., Ekaykin, A., Fain, X., Lim, S., Schotterer, U., Lipenkov, V., Toropov, P.
• Format: Text
• Language: English
• Published: 2015
• Subjects: ice core
• Online Access: https://www.documentation.ird.fr/hor/fdi:010066077

A 182m ice core was recovered from a borehole drilled into bedrock on the western plateau of Mt. Elbrus (43 degrees 20' 53.9 ' N, 42 degrees 25'36.0 ' E; 5115ma.s.l.) in the Caucasus, Russia, in 2009. This is the first ice core in the region that represents a paleoclimate record that is practically undisturbed by seasonal melting. Relatively high snow accumulation rates at the drilling site enabled the analysis of the intraseasonal variability in climate proxies. Borehole temperatures ranged from -17 degrees C at 10m depth to -2.4 degrees C at 182 m. A detailed radio-echo sounding survey showed that the glacier thickness ranged from 45m near the marginal zone of the plateau up to 255m at the glacier center. The ice core has been analyzed for stable isotopes (delta O-18 and delta D), major ions (K+, Na+, Ca2+, Mg2+, NH4+, SO42-, NO3-, Cl-, F-), succinic acid (HOOCCH2COOH), and tritium content. The mean annual net accumulation rate of 1455mmw : e : for the last 140 years was estimated from distinct annual oscillations of delta O-18, delta D, succinic acid, and NH4+. Annual layer counting also helped date the ice core, agreeing with the absolute markers of the tritium 1963 bomb horizon located at the core depth of 50.7mw : e : and the sulfate peak of the Katmai eruption (1912) at 87.7mw : e : According to mathematical modeling results, the ice age at the maximum glacier depth is predicted to be similar to 660 years BP. The 2009 borehole is located downstream from this point, resulting in an estimated basal ice age of less than 350-400 years BP at the drilling site. The glaciological and initial chemical analyses from the Elbrus ice core help reconstruct the atmospheric history of the European region.