NEW CHEMICAL STRATIGRAPHY OVER THE LAST MILLENNIUM FOR BYRD-STATION, ANTARCTICA

A 164 m-deep, 10 cm diameter, ice core was obtained at Byrd Station su rface camp (NBY89), West Antarctica in November 1989. In addition, two 10-m shallow cores were recovered at 14 km and 29 km distances upstre am from the main core; 2 m-deep pits were dug at each drilling locatio n. Over 2300 individual samples were analyzed for ionic concentration levels in continuous but selected depth-intervals. Results of study pr ovided a continuous 1360-year chronology for the 164-m core based on m ultiple cross-correlations of deltaO-18. ECM and ionic chemistry data combined with megascopic stratigraphy and physical properties. Average ionic concentration values over the entire core profile are CH3SO3-, 0.08; Cl-, 1.52; NO3-, 0.76; SO42-, 1.10; Na+, 1.13 and Mg2+, 0.30 in mueq kg-1. Between 60 m to 164 m, the average HCOO- concentration leve l is 0.04 mueq kg-1. Measurements of NH4-, K- and Ca2+ were mostly bel ow instrument detection levels. Except for CH3SO3-, the chemistry curv es show no significant trends with time. Excess SO42- reveals distinct seasonal cyclicity over the entire 164 m core but CH3SO3- and NO3- co ncentrations also show seasonal variations, most clearly over the top 2 to 4 m. 25 excess SO42- peaks greater than 5 kg km-2 are identified as volcanic in origin. 5 prominent excess SO42- volcanic peaks below 9 0 m are laterally traced to the same time-unit events near the top of the Byrd Station deep core recovered in 1968, thereby establishing a r eliable chronological connection between the new NBY89 core data with the older ice core records which extends back to Early Wisconsin age.