Geochemical and ε Nd Results from Larsen-B Ice Shelf and Marie Byrd Land Sediments: Implications for Provenance Tracing

We present new sediment provenance data from the Larsen-B (LIS-B) embayment on the northeast Antarctic Peninsula, and Marie Byrd Land (MBL). The bedrock in these areas have characteristic lithologic and geochemical signatures that are preserved in glacially transported and deposited sediment. These signatures may allow us to identify ice rafted debris and fine-grained sediment that originate from these two areas, which have undergone recent ice shelf retreat and collapse. This study involves the determination of characteristic features of near-shore glacial-marine sediment from each source area that are representative of the sub-ice bedrock, which is largely inaccessible. Bulk sediment elemental abundances including major, minor, and trace elements including heavy metals and rare earth elements (REEs) were measured from the < 63 micron fraction. Preliminary geochemical data from the Larsen Ice Shelf Embayment yields Al/Ti values of 21-30, suggesting an upper continental crust source. ε_Nd values range from -1.9 to -4.9, which are distinctly different from both the high negative values observed from the central Weddell Sea to the east, and from the low positive values from the northwestern Antarctic Peninsula (Roy et al., 2007). Samples from Marie Byrd Land yield Al/Ti values of 15-21 suggesting an average continental crust source or possibly a mixture of upper continental crust and mafic intrusions. ε_Nd values from samples off the Pine Island Ice Shelf and Thwaites Ice Tongue range from -2.3 to -8.3, which bracket the offshore ε_Nd values reported by Roy et al., 2007.