Annual resolution µXRF analysis
The quantification of the dust fraction at Auel is currently taken to annual resolution by the use of continuous µXRF for the cores of ELSA-20. Semi-quantitative element analysis was performed on the cores HM4 and AU4 with an Avaatech X-ray fluorescence core scanner at Max Planck Institute for Chemistry in Mainz. The measurements were obtained with a down-core resolution of 0.5 mm and a cross-core slit size of 12 mm. Element data are given in counts per second, which have been used to calculate elemental intensity ratios, thereby reducing noise.
The data are used to approximate the diatom content of the sediment with a Si/Al ratio (Sirocko et al. 2021), because most of the silicium is from diatoms. This ratio, however, contains also Si proportions from quartz, which is abundant in the eolian dust quartz particles. For quantification of the eolian proportion, we normalized Si/Al by Corg(chlorins) and applied a principle component analysis (Sirocko et al, in prep.). The resultant curves separate the silicium fraction from diatom relative to the silicium from the quartz fraction. The resultant curve is most similar to the older ELSA-Dust-Stack-2009 (see above), but presents the abundance of eolian grains now on the ELSA-20 time scale.