Paper No. 5
Presentation Time: 8:00 AM-12:05 PM
SEDIMENTOLOGICAL ANALYSIS OF HOLOCENE AND GLACIAL EVENTS IN BAFFIN BAY, LABRADOR SEA
We evaluated the sedimentological expression of paleoclimate events from a marine sediment core off the west coast of Greenland, an environment sensitive to climate change. The 155 cm long trigger core 16TWC and its associated piston core were taken during CCGS Hudson Expedition 2008-029 in Baffin Bay (70.46°N; 64.66°W; 2063 m water depth). Sedimentological measurements on the trigger core were made at 1 centimeter resolution using several instruments. Proxies measured include diffuse spectral reflectance (DSR) using a Minolta CM2600D UV/VIS Spectrophotometer, grain-size spectra using a Mastersizer 2000, and elemental analysis using an Innov-X Alpha series handheld XRF scanner. An age-depth model was created by correlating a*, a reflectance color measurement, with the GISP2 δ18O record which is in close proximity to our core. Our preliminary age model implies 16TWC extends to 30,000 calendar years B.P. By applying Varimax-rotated, Principal Components Analysis to our grain-size spectra, five grain-size factors were extracted that explain the relative variance of the processes affecting sedimentation. The driving processes behind each factor can be inferred by comparing the shapes of these grain-size factors to previously identified grain-size factors from Darby et al., (2009). Grain-size factor 1 represents anchor ice and reaches a local maximum during the Last Glacial Maximum and minima during the Bolling-Allerod, Younger Dryas, and the 8.2 ka events. Grain size factor 2, linked to nepheloid processes, was maximal at the time associated with Heinrich event 2 (~24 ka), and exhibited a saw-toothed shape declining to the Younger Dryas. These saw-toothed oscillations may represent the Bond Cycle from 24 ka to 12 ka. The elemental calcium record, signifying detrital carbonate from the Laurentide Ice Sheet, correlated well with grain size factor 2. The three remaining grain size factors likely represent random ice rafted debris events. The results show the local expression of the deglaciation following the last glacial maximum.