THE EFFECT OF A WESTERN ANTARCTIC ICE SHEET COLLAPSE ON NUTRIENT RECYCLING RATES DURING MARINE ISOTOPE STAGE 31: INITIAL FINDINGS

Expedition 177 of the International Ocean Discovery Program yielded valuable cores from the Southern Ocean. Site 1094, taken southwest of the tip of Africa in the circum-Antarctic opal belt, contains a span of time in the Early Pleistocene (roughly 1 million years ago) that covers the marine oxygen-isotope stage 31, a hypothesized period of West Antarctic Ice Sheet collapse. This study evaluates the taphonomic condition of Fragilariopsis kerguelensis, the most common diatom in Southern Ocean sediment, recovered from this site as a proxy for nutrient recycling in the upper water column. The core depth (~118m-123m below the seafloor) includes a time interval before, during, and after the collapse. By cataloging morphological dissolution of this prevalent diatom, links between the collapse and subsequent release of nutrient rich sediments and upper water column nutrient cycling can be evaluated. Additionally, the effects of a dissolved silica influx to the tropics, known as silica leakage, will be addressed.