X-ray fluorescence (XRF) scans of push cores from Loki's Castle and Favne vent fields, Mohns Ridge, geochem mode

Samples are push cores and were pushed into sediment by the ROV’s manipulator arm. Once recovered shipboard cores were frozen (2018-691-DD) or refrigerated (2019-624-FA) until return to shore. Samples were donated from Field Activity 2018-691-DD, and no USGS attendees were present. Amy Gartman attended 2019-624-FA.

Cores 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 between 0.5 and 1 cm downcore, automated by the motors on the MSCL. The XRF was run in "geochem" mode with two beams at 20 seconds each. 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 percent. Elements lighter than Mg are grouped into the "Light Elements" (LE) category in order to maintain a closed compositional dataset. XRF data are provided a two comma-delimited file for push cores ROV12PC02, ROV17PC01, ROV17PC02, ROV17PC03. ROV22PC01, ROV22PC02, ROV22PC03, ROV22PC04, ROV22PC05, ROV22PC07, ROV22PC08, ROV26PC01, ROV26PC03, and ROV28PC02.