Lots of research has been conducted on Australia’s late glacial (30,000-20,000 years ago), deglacial (20,000-10,000 years ago), and Holocene (the last 10,000 years) climate; however, few climate reconstructions exist for northwestern Australia due to a lack of data. Drivers of climate variability over these time periods are important to understand because local climate adjusts to climate forcing with different identities and scales.
We analyzed stalagmites from Cape Range (21.2°S, 113.7°E), Western Australia, in order to reconstruct the climate of Cape Range during these periods. Isotopic ratios of oxygen (18O/16O) and carbon (13C/12C) change as local or regional environment changes and therefore their values in stalagmite calcite (CaCO3) can be an indicator of climate change. By analyzing the stable isotopic ratio in two stalagmites, AUS-117 and AUS-118, we were able to gather more information during the last glacial.
U-series dating was conducted to construct stalagmite chronologies and age models were developed to link isotopic ratio data with the dates obtained. A thorough isotopic ratio analysis has been done to (1) evaluate factors that control stable isotopic ratio; (2) compare variations in isotopic trends with climate records; (3) retrace changes in rainfall, temperature and vegetation of Cape Range from late glacial to Holocene.
We found that the 18O/16O ratio remains stable during the late glacial when the Westerlies was closest to Australia and gets lighter during deglacial as the Westerlies migrated southward. The ratio becomes lighter during early Holocene, and heavier in middle Holocene, possibly due to variations in the summer monsoon.
Ni An, ’14
Majors: Geology, Environmental Studies
Sponsor: Rhawn Denniston