The Antarctic Peninsula is one of the fastest warming regions on earth, yet the region’s Holocene paleoclimate is poorly constrained. Lapeyrère Bay is a fjord on the eastern side of Anvers Island, located off the Western Antarctic Peninsula. Anvers island has a maximum elevation of 2400m, and experiences colder temperatures and more precipitation than the South Shetlands which are ~230km to the north. Two glaciers enter Lapeyrère bay, one large and vulnerable to avalanching, the Iliad Glacier, and one smaller glacier confined to a northern unnamed cove. Though a large amount of data has been gathered by cruises in Lapeyrère Bay, very little has been published on the fjord’s glacial retreat history or sediment flux. The primary purpose of this study is to reconstruct the glacial retreat and sediment flux histories of Lapeyrère Bay using cores for chronology and facies analysis, and multibeam swath bathymetry data for identifying seafloor morphological features.

Preliminary core data from the proximal northern flank of Lapeyrère Bay shows a greenish grey sandy mud with scattered pebble and sand lens lithology. A kasten core and a jumbo piston core taken coincidently in the distal-most part of the fjord are largely diatomaceous sediment grading into grey silty mud with thin sandy turbidites. Multibeam data has exposed seafloor features including a grounding zone wedge at the entrance of the unnamed cove of northern Lapeyrère bay, drumlins, glacial lineations, and a glacial outwash fan near the ocean-termination of the Iliad glacier.

Additionally, this study seeks to assess the effectiveness of a novel radiocarbon (14C) chronological method of dating Antarctic Peninsula cores lacking sufficient calcareous material for carbonate 14C dating. The method being tested is ramped pyrolysis, which dates individual fractions of organic material. It is hypothesized that ramped pyrolysis will improve upon bulk Acid Insoluble Organic Material (AIOM) dating, as AIOM consistently dates samples as erroneously old. Performing ramped pyrolysis 14C dating and carbonate 14C dating on the same cores and comparing the resulting ages will address this hypothesis.

Carbonate radiocarbon dating has been completed for cores taken in the proximal fjord. Four dates from a 20.3m drill core yield an average sedimentation rate of 2.2mm/yr. Four dates from the nearby 293cm gravity core yield a sedimentation rate of 1.4mm/yr. Ramped pyrolysis has been performed on a total of nine samples, six taken from the proximal drill core and three taken from the distal-most gravity core of the fjord. In order to know the amount of sample necessary for pyrolysis TOC percentages were found for each sample. The average proximal sample TOC is 0.22%, and the average distal sample TOC is 0.55%. These values show a trend of increasing TOC values with increasing oceanic influence in the distal fjord. Pyrolyzed samples were dated at the Woods Hole Oceaceanographic Institution, and results are discordant with previous ramped pyrolysis studies. Dates from each sample are less dispersed than expected, though two show clear temperature plateaus indicating the true age of the sample. These true ages are neither consistently older nor younger than the carbonate 14C dates taken from foraminifera in the same samples.