LATE PLEISTOCENE TO EARLY HOLOCENE CLIMATE VARIABILITY FROM A HIGH-RESOLUTION SPELEOTHEM RECORD IN THE SOUTHEASTERN APPALACHIAN REGION

Abrupt climate changes including Heinrich events, Dansgaard-Oeschger (D/O), the Last Glacial Maximum (LGM), Younger Dryas, and Bond events have been documented in many terrestrial records since the late Pleistocene. A high-resolution speleothem record from Morril's Cave (aka Worley's Cave) in the southeastern Appalachian region demonstrates millennial-scale climate variability associated with these abrupt events. This is a slow-growth stalagmite with an average growth rate at approximately 4 μm/year spanning between 42 to 9 ka B.P. The chronology of the stalagmite was determined by more than 20 precise U-Th dates. Stable isotope analysis was done with a sampling interval of 0.5 mm and trace metal analysis (Sr concentration) was conducted using a Bruker Artax μ-XRF spectrometer at 0.33 mm interval. The timing of Heinrich events 1, 3, and 4 are well-constrained by abrupt increases in δ¹⁸O and δ¹³C values along with Sr concentrations. Extremely slow growth (less than1 μm/year) occurred during the LGM and the second Heinrich event (H2) with elevated δ¹⁸O and δ¹³C values as well as Sr concentrations. Most D/O events occurred before the LGM are recorded with positive shift of δ¹⁸O values. Younger Dryas event is clearly demonstrated by significant increases of δ¹⁸O and δ¹³C values along with Sr concentrations. Three Bond events in the early Holocene are characterized by abrupt increases of δ¹⁸O and Sr concentrations of the speleothem record.