Crystal-size and microparticle record in the ice core from Dome Summit South, Law Dome, East Antarctica

Abstract

An investigation of crystal-size and microparticle variations has been carried out for the 1196 m ice core retrieved from Dome Summit South (DSS) near the summit of Law Dome, East Antarctica. Results show that for ice deposited during the Holocene (depth <1103 m), microparticle concentrations are low. Variations of crystal size within the Holocene ice are due to growth with time at a temperature-dependent rate, and recrystallisation as a consequence of the ice flow. In the DSS ice core the highest microparticle concentration occurs close to the depth (1133 m) at which oxygen isotope ratios exhibit the greatest negative values, i.e. the Last Glacial Maximum (LGM). Also at this depth, crystal size reduces sharply from a general crystal growth trend above to near minimum core values below. For ice originating during the LGM, the concentration of particles is an order of magnitude greater than the mean Holocene concentration. Laboratory annealing tests at -1°C confirm the retarded crystal growth in the high-microparticle-concentration ice.