RECONSTRUCTING EARLY HOLOCENE DECADAL-RESOLUTION TEMPERATURE USING BRGDGTS FROM LAKE SEDIMENTS, WESTERN GREENLAND

The western margin of the Greenland Ice Sheet advanced and retreated rapidly during the early Holocene, likely in response to the 9.3 and 8.2 ka abrupt cooling events. These cooling events are documented in records from Greenland ice cores, however we know little about early Holocene decadal-scale temperature change near the margins of the Greenland Ice Sheet. This study located on Nuussuaq on the western coast of Greenland investigates early Holocene abrupt temperature change using the MBT-CBT proxy based on branched glycerol dialkyl glycerol tetraethers (brGDGTs). We derive an age depth model for our sediment core from Sikuiui Lake using 12 radiocarbon-dated terrestrial macrofossils. Multiple sedimentological and inorganic geochemical records have also been generated from this core. We analyze GDGTs at decadal-resolution, using high performance liquid chromatography-mass spectrometry, to determine GDGT concentrations and ratios. Our findings indicate that most of the samples do not contain isoprenoid GDGTs. However, brGDGTs are present in most of the samples, with particularly abundant signals of the major ions, similar to other small lakes on western Greenland. We will present our decadal-scale br-GDGT-inferred temperature record in combination with the multi-proxy records already generated from this lake.