X-ray Fluorescence (XRF) scans of vibracores from Searsville Lake, Jasper Ridge Biological Preserve, Stanford, California

Cores were collected on October 29, 2018. A handheld global satellite navigation system (GNSS) receiver was used to determine the locations of sediment samples. Cores were segmented into 150 cm (or shorter) sections in the field and split into "working" and "archive" halves in the lab. Sediment surfaces were cleaned and smoothed on the "archive" halves of split cores. A four micron-thick ultralene film that is transparent to x-rays was applied to the sediment surface in order to protect the XRF window. Cores were loaded onto the track of a Geotek Multi Sensor Core Logger (MSCL) with an Olympus Delta Professional XRF gun mounted to an arm that moves the XRF sensor vertically on and off the core surface. The XRF sensor was calibrated before each scan using a 316-alloy reference coin. The XRF window is 1x1 cm square and measurements were collected every 1 cm downcore, automated by the motors on the MSCL. The XRF was run in "geochem" mode with two beams at 20 seconds each (with a 16-19 second XRF-live time). Data were processed with Geotek MSCL software and elemental abundances are reported in parts per million(ppm). Geochem mode processes the data as a closed sum compositional dataset, assuming that all components add up to 100%. Elements lighter than Mg are grouped into the "Light Elements" (LE) category in order to maintain a closed compositional dataset. Geochem XRF data from each core segment were merged into two datasets, one for each of the two vibracores. XRF data are provided in two comma-delimited files (.csv) corresponding to each of the two vibracores.