Novel rock luminescence dating of snow petrel stomach-oil deposits from East Antarctica

Abstract

The discovery of long-term accumulations of snow petrel stomach-oil deposits in Antarctica have provided an excellent opportunity to reconstruct changes in climate, ice-sheet thickness and sea ice. However, providing age constraints on the deposition of these biological accumulations can be challenging, particularly when they extend beyond the radiocarbon age limit (ca. 55 ka). Luminescence dating is successfully used here to provide accurate ages for rocks underlying and incorporated into snow petrel stomach-oil deposits in East Antarctica. The agreement between the different luminescence signals measured from K-feldspars, in addition to the independent age control (radiocarbon dating) gives confidence in the results. We show the potential for reconstructing ice-sheet histories from multiple burial events with prior exposure durations recorded in the luminescence depth profiles of the rocks. Our study extends beyond the traditional sedimentary contexts usually used for luminescence dating, and into biological accumulations, which has not previously been done. We show that rock luminescence dating can overcome some challenges of using radiocarbon dating for biological accumulations (e.g. young carbon contamination, marine reservoir uncertainty) and can potentially extend the dateable age range to at least Marine Isotope Stage 5 according to the saturation limit of the luminescence signal measured for these samples. This is key for using these stomach-oil deposits to quantify the contribution to sea-level rise provided by Antarctic Ice Sheet retreat, and changes in sea ice during the last warm interglacial period experienced on Earth.