HOLOCENE PALEOCLIMATIC EVIDENCE FROM A CORE IN THE EASTERN BASIN OF LAKE ERIE: A MULTIPROXY APPROACH

Lake Erie is the shallowest and volumetrically the smallest of the Great Lakes and therefore, it is most sensitive and vulnerable to environmental and hydrologic changes, including perturbations by humans. Understanding long term variability of Northern Hemisphere climate is crucial for make educated future predictions. Although the major climatic shift of the last glacial period have been a considerable topic, less attention has received the Holocene climate variation. Therefore, this study was carried out to understand the regional climate variability during the Holocene using multiple proxies on a high-resolution sediment core from the eastern basin during the last 12.0 kyr.

A 1664 cm long piston core (from Case Western Reserve University) was used to identify climatic signals and this site mainly receives sediment from Detroit River fed by precipitation and then transport through western and central basins. Diffuse Spectral Reflectance (DSR), Particle Size Analysis, Magnetic Susceptibility (MS) were measured about 10 cm resolution. Varimax rotated Principal Component Analysis (VPCA) was performed for color reflectance data (DSR-VPCA) to extract principal components that represent climate variability. Previously published (Clotts et al., 2005) radiocarbon data based on microfossils was used to develop the age model.

The core represents climatic signals from 11.7 cal. kyr BP to 3.4 cal. kyr BP. Downcore variability data clearly indicates the cold, dry climatic event from last glacial to 11.0 cal. kyr BP and warm, wet period, began at about 11.0 cal. kyr BP, culminated at 9.5 cal. kyr BP and came to its end at about 8.5 cal. kyr BP. After that, the climate gradually become colder and drier until about 8.0 cal. kyr BP and again the wet-warm climate become dominant which represents the Holocene maximum period around 5.5 cal. kyr BP. Also, our records indicate that another short term climatic oscillation occurred at 4.2 cal. kyr BP which was a cold and drier event. However, our data fit other proxy records of regional climate change such as 8.2 cold event from early Holocene climate oscillations in Greenland ice cores. The main driving force for the climatic evolution in the Great Lakes region during the Holocene period is likely the solar insolation change and major atmospheric circulation changes.