Improving Antarctic Sediment 14C Dating Using Ramped Pyrolysis: An Example from the Hugo Island Trough

Abstract

To improve the chronology of sediments containing information about Holocene ice shelf and oceanic dynamics in the vicinity of the Antarctic Peninsula, we compare bulk acid-insoluble radiocarbon dating to ramped pyrolysis14C dating in a sediment core containing ample organic material. This core spans the last 12,000 yr of open-shelf sedimentation in the Bellingshausen Sea, western Antarctic Peninsula. By estimating the spectrum of14C ages within a given core horizon, the ramped pyrolysis14C method separates organic carbon relative to thermal stability, isolating younger parts of the mixture from older ones and providing an estimate of the geological uncertainty inherent in a bulk14C age. Employing the ramped pyrolysis14C method to this core demonstrates variable bulk14C age bias and increasing age spectrum downcore, neither of which can be associated with major changes in lithology of the core. The chronology of the sediment core using the youngest ages from the ramped pyrolysis technique allows for correlation between nearby Palmer Deep sediments and these sediments from the Hugo Island Trough.