New chemical stratigraphy over the last millennium for Byrd Station, AntarcticaTellus, Vol. 46B, p. 40-51, 1994
C.C. Langway, Jr. and K. Osada
Ice Core Laboratory, Department of Geology, State University of New York at Buffalo, 4240 Ridge Lea Road, Buffalo, NY 14260, USA.
H.B. Clausen and C.U. Hammer
Geofysisk Afdeling, Niels Bohr Instituttet for Astronomi, Fysik og Geofysik, Københavns Universitet
H. Shoji and A. Mitani
Department of Earth Science, Toyama University, Gofuku-cho, Toyama 930, Japan.
A 164 m-deep, 10 cm diameter, ice core was obtained at Byrd Station surface camp (NBY89), West Antarctica in November 1989. In addition, two 10-m shallow cores were recovered at 14 km and 29 km distances upstream from the main core; 2 m-deep pits were dug at each drilling location. Over 2300 individual samples were analyzed for ionic concentration levels in continuous but selected depth-intervals. Results of study provided a continuous 1360-year chronology for the 164-m core based on multiple cross-correlations of δ18O, 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 μeq kg-1. Between 60 m to 164 m, the average HCOO- concentration level is 0.04 μeq kg-1. Measurements of NH4+, K+ and Ca2+ were mostly below instrument detection levels. Except for CH3SO3-, the chemistry curves show no significant trends with time. Excess SO42- reveals distinct seasonal cyclicity over the entire 164 m core but CH3SO3- and NO3- concentrations 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 90 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 reliable chronological connection between the new NBY89 core data with the older ice core records which extends back to Early Wisconsin age.