Climate-related changes in lead isotopes over the past 800,000 years in the EPICA Dome C Antarctic ice core

초록

record of the Pb isotopic compositions from the 3,260 m deep Antarctic ice, drilled at Dome C on the East Antarctica as part of the European Program for Ice Coring in Antarctica (EPICA), covering the past 800 kyr, is presented. Pb isotopic compositions were determined using a thermal ionization mass spectrometry (TRITON, Thermo Scientific). All sample handling and analytical operations were performed under a class 10 laminar airflow bench or booth in class 1000 clean laboratories. Lower 206Pb/207Pb ratios are found during glacial periods when Pb concentrations are high, while higher values are found during warm periods when Pb concentrations are low. The characteristics of Pb isotopes vary with climatic conditions, which is likely associated with the relative strength of dust and volcanic contributions to Pb deposition in central East Antarctica. Using Pb, Sr and Nd isotopes in Antarctic deep ice cores, previous studies suggested that Southern South America (SSA) was an important source of dust in Antarctic ice during both glacial and interglacial periods. They also demonstrated that Australia was not a major component of Antarctic dust, whatever the period. Here we present the first Pb isotopic evidence that dust from Eastern Australia could be an important source of Antarctic dust between 300 kyr BP and 600 kry BP.