| Summary: | During the summer 2011 Research Experience for Undergraduates (REU) program, six students led by two research scientists traveled to the island of Spitsbergen, Svalbard and collected six sediment cores across the face of a tidewater glacial system. Ice-proximal (<500 m from the ice face) sedimentation at the Kronebreen-Kongsvegen ice face has been well studied through the REU program, but never before has geochemical data been considered. Voluminous sediment originates from two sources at this site: a subglacial river at mid-ice face and an ice marginal stream at its southern terminus . This study uses both sedimentological and geochemical methods to better characterize sediment sourcing and depositional trends across the ice face. Core analyses included manual descriptions, granulometry, and comparison of GRAPE density measurements, magnetic susceptibility profiles and x-radiographs. Additionally, x-ray fluorescence (XRF) detection scans provide high-resolution down-core relative element abundances for the sediment cores. Down-core ratios of major and minor elements provide information on sediment organic matter content, turbidite deposits, and grain size trends. Quantitative analyses were made possible using principal component analysis (PCA), a statistical analysis tool that isolates dominant factors in a data matrix into ‘factor loadings’. PCA was used on XRF datasets to isolate dominant elements and geochemical signatures of sediments from each source. In all cores, Fe, K, Mn, and Rb or Ti comprise a factor loadingthat represents the sediment clay-size fraction. Ti is highly correlated (76.6%) in mid-ice face clays, and Rb is highly correlated (82.3%) in delta-proximal clays. Si, Ca and Ti comprise a second factor loading representative of a larger grain-size fraction by the delta deposited by the ice-marginal stream. Ca is highly correlated with Si and Ti (97.9%) in grey silty-sands, but on its own comprises a third factor loading in red muds (17% total variance), perhaps representing erosive activity rather than a particular grain size. This evidence suggests that alternating red muds and grey silty sands deposited ahead of the delta represent two different sediment sources rather than distinct depositional processes. This research lays the groundwork for further statistically rigorous testing of XRF geochemical datasets, useful for understanding sedimentation in the tidewater periglacial environment.
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