Summary
The Dome Summit South ice core from Law Dome, East Antarctica is 1200 m long and reveals an unusually high accumulation rate for Late Holocene precipitation (640 kg m2/a), dating to 90,000 years before present (BP) at its base. The site shows evidence of large accumulation changes during the last deglaciation period which are explored here through variations in the inferred microparticle flux. This record is investigated using a Coulter Multisizer to provide concentration and size distribution of the insoluble fraction of ice core samples during this period. The observation is an abrupt decline in concentration from 36, 700 to 2, 000 particles per ml (or from 100 to 6 ppb) between 17 and 18, 000 years BP. There is also a significant shift in average grainsize through this period from approximately 1.6 to 2.1 µm. These changes are synchronous with the abrupt warming period identified through the oxygen isotope record from the same ice core. The timing of this decline agrees with records from Vostok and Dome C ice cores, as does the grainsize shift, however the flux ratios are significantly different. The abrupt changes common to all sites are considered to be in response to altered trajectory pathway characteristics and provenance during the period of rapid climatic warming. The flux variation between sites is linked to the relatively high accumulation and low coastal position of the Law Dome ice core compared with the low accumulation, high inland sites of the other deeper and older cores.