XRF scanning of discrete samples - A chemostratigraphic approach exemplified for loess-paleosol sequences from the Island of Susak, Croatia

摘要

X-ray fluorescence (XRF) scanning of discrete samples provides a time-and cost-efficient alternative to conventional geochemical analyses of discretely sampled paleoenvironmental archives. Loess-paleosol sequences (LPS) as complex terrestrial archives are thus predestinated for bench marking this new application of the well-established XRF scanning technology. Stratigraphically incomplete outcrops, like those on the Island of Susak (Croatia), are unique paleoenvironmental archives at least for the penultimate and last interglacial/glacial cycles and provide ideal test sites. Available proxy data from previous investigations on Susak ensure validation of conclusions drawn from XRF scanning-derived data.Three representative profiles were studied to examine the potential of XRF scanning-derived element ratios as proxy for environmental processes: (1) Ca/Sr for the strength of ubiquitously present secondary calcification; (2) Rb/K for the intensity of weathering; (3) Ti/Al and Ti/Zr for changes in wind speed with Zr being additionally indicative for sediment recycling; (4) Si/Al for changes in grain-size; and (5) Br and Cl as proxies for sea spray. Furthermore, we established a multivariate statistics-based chemostratigraphy to facilitate profile correlation and to improve lithostratigraphic characterization. In conclusion, this study demonstrates that XRF scanning of discrete samples from LPS is a valuable tool for paleoenvironmental reconstruction.