PALEOCLIMATIC CHARACTERISTICS OF LATE PLEISTOCENE/ HOLOCENE CARBONATES IN THE ARCTIC OCEAN BASED ON A PCA AND ELEMENT CORRELATION STUDY OF DOWNCORE XRF DATA

Due to its sensitivity to global climatic variations, Arctic Ocean sediment deserves study as key evidence of past paleoclimatic events and to aid predicting future change. Terrigenous carbonate sedimentation in the Arctic Ocean is of particular paleoclimatic interest as it can be traced back to output from the Laurentide Ice Sheet. This material is primarily delivered by melt water fluxes and IRD and distributed by ocean/wind circulation. In the current study, 13 sediment cores recovered during the 2005 HOTRAX expedition across the Arctic Ocean provide coverage from the two main wind-driven circulation patterns: the Beaufort Gyre and Transpolar Drift. Varimax-rotated Principle Component Analysis of the downcore XRF analyses for 26 major/trace elements yields seven factors. The PCA results were compared with published late Pleistocene/Holocene core data of the region. The study identified factors presumably related to terrestrial sources (F1, enhanced Ti-K-Rb-Fe-Ba-Cr), changes in Laurentide Ice Sheet (F3, enhanced Ca-P-I), and Interglacial-interstadial environments (F6, enhanced Mn-Ni-Cu). Factors, F2 (enhanced Sn-Sb-Cd-Se-Ag), F4 (enhanced Fe-Mo-As-Co-Zn), F5 (enhanced P-Cl-S) and F7 (enhanced Sr-Zr) relate to various glaciomarine processes that will be discussed elsewhere. Downcore variations of the factors help to identify glacial-interglacial cycles and associated carbonate pulses. Enhanced Ca influx occurred during glacial/stadial periods as IRD and meltwater suspension, similar to Heinrich events in the North Atlantic. The detrital carbonate clast and clastic IRD records from JPC8 (Polyak et. al., 2009) are well correlated with corresponding F3 peaks measured in the same core. Mn-rich layers (F6 peaks) indicate interglacial/ interstadial periods and are generally anticorrelated with Ca pulses. As compared to the Beaufort Gyre, the Transpolar Drift Pleistocene sedimentation is characterized with only a few shallow carbonate spikes, which indicate low amounts of the Laurentide material in the Transpolar Drift.