High stands and overflow history of glacial Lake Chicago and downstream impacts on Gulf of Mexico δ18O values
Dr. B. Brandon Curry, Illinois State Geological Survey
Linked and complex relationships between runoff from deglacial sedimentary systems to ocean basins likely contribute to the murky global signals of Heinrich Stadial 1 (also known as the “Mystery Interval”) from ca. 17.5 – 14.5 cal ka. However, precise chronologies linking meltwater sources, transport, and oceanic sinks are lacking for this period. A probability density function of new and published radiocarbon dates shows Lake Chicago, a large, glacial meltwater lake adjacent to the Lake Michigan Lobe of the Laurentide Ice Sheet, had two high stands, the Glenwood and Calumet Phases, which occurred from ca. 17.0 – 15.0 and 14.2 – 12.4 cal ka, respectively. Ages of the highest stands of Lake Chicago and high sediment accumulation rates at 16.5, 16.0, 15.1, 14.1, and 13.4 cal ka temporally correspond to large pulses of meltwater recorded in the δ18O values of G. ruber (pink and white foraminifera) in sediment cores from the Orca Basin (Gulf of Mexico). Thus, we conclude overflow of meltwater via the Chicago Outlet during high stands produced several large downstream events and coeval stable oxygen isotope decreases in the Gulf of Mexico.
About the speaker
Dr. Curry is a Principal Research Scientist and head of the Quaternary and Engineering Geology section of the Illinois State Geological Survey, Prairie Research Institute. All of his degrees have been in geology, including a Bachelor of Arts degree from the University of California at Santa Barbara, a Masters from Purdue University, and a PhD from the University of Illinois at Urbana-Champaign. He has been with the ISGS almost his entire professional career, about 34 years. He specializes in Illinois’ Quaternary geology, focusing on its history, stratigraphy, paleopedology, environmental geology, surficial mapping, and paleolimnology.