DEGLACIAL AND HOLOCENE ENVIRONMENTAL CHANGE RECORDED IN LAKE SEDIMENTS FROM THE SNOWY MOUNTAINS, KOSCIUSZKO NATIONAL PARK, SOUTHEASTERN AUSTRALIA

Glacial tarns in the Snowy Mountains, the only glaciated portion of mainland Australia during the Last Glacial Maximum (LGM; ~20 ka), provide a unique opportunity to analyze continuously accumulating sediments since that time. An 8.2 m core extracted in 2016 from Blue Lk, the largest of the tarns, indicated that the area experienced several dramatic climatic shifts (cold/dry vs warm/wet) between 18 - 11 ka, two of which may correspond to the Antarctic Cold Reversal and Younger Dryas events, respectively. Overall warmer/wetter conditions during most of the Holocene were punctuated by two possible cooler/dryer events ca.10.8 - 9.7 ka and 2.2-1.2 ka.

To test whether these events represent local vs regional environmental and climatic fluctuations, we recently collected an additional suite of sediment cores from two other tarns in the Snowies, Lk Albina and Club Lk. Preliminary stratigraphic analyses (MS, XRF, visual, organics, grain size) suggest that the cores from Lk Albina (~5 m) preserve high-resolution records equivalent to the Blue Lk core; 14C dating indicates the cores extend through the deglaciation and perhaps into the LGM. The Club Lk cores (~2 m) preserve shorter, less variable records that extend through most of the Holocene but not into the Pleistocene.

Preliminary assessment of the Lk Albina stratigraphy suggests relatively fast sedimentation rates during deglaciation dominated by cold/dry conditions punctuated by brief warmer/wetter periods. Holocene sediments in both lakes indicate slower sedimentation rates with consistent warmer/wetter conditions. Ongoing analyses and improvements to our age-depth models will allow us to refine these interpretations and test possible correlations to known hemispheric climate fluctuations (e.g., ACR, YD). We will present these updated results at the conference.