Holocene DIATOMS Recovered from Shaldril I Cores, Maxwell

High-resolution Holocene sediment cores from the continental shelf of Antarctica are integral to the study of recent climate transitions, but such records are rare. The inaugural SHALDRIL I cruise to Maxwell Bay along the Northern Antarctica Peninsula, however, recovered the most expanded record to date at Site NBP05-02-1B. More than twice as long as any other such Antarctic sequence, the 108.2 m section dates back 13,480 yr B.P. Presented here is a record of climate variation interpreted from analyses of the diatom content.

Diatoms have proven to be a useful tool in the study of paleoclimate. Analyses completed here include species diversity, total diatom abundance (valves per gram of sediment), Eucampia antarctica var. antarctica to E. antarctica var. recta ratio, Eucampia index, Chaetoceros resting-spore percent, Chaetoceros hyalochaete to C. vegetative ratio, and Thalassiosira antarctica T2 percentage. The analyses show a continuous sea-ice assemblage with minor fluctuations in response to changing sea-ice conditions. Other than the Thalassiosira antarctica T2 percentage, all analyses show a prominent warming period identified as the Mid-Holocene Climatic Optimum. Thalassiosira antarctica T2 percentage marks a period of deglaciation at approximately 11 ka. This episode of deglaciation has been documented in other studies and is believed to mark the onset of present-day ice conditions.