Portable X-ray Fluorescence (PXRF)

Energy-Dispersive X-Ray Fluorescence (ED-XRF) is a rapid, non-destructive technique for determining qualitative and quantitative changes in chemical composition. Aboard the JOIDES Resolution, pXRF is used for measuring points on section halves, rock pieces, and sometimes powders. Spots are typically irradiated at multiple conditions to excite and measure a wide range of elements. The peak intensity changes (we do not provide concentrations) are then be used to help recognize and define major chemo-stratigraphic units without the need for destructive sampling.

The data shown in the element columns are not given a unit to indicate that they are uncalibrated data on a pure element basis (not element oxide). Energy-Dispersive X-Ray Fluorescence (ED-XRF) techniques on section halves or whole rock samples must be further reduced in order to produce concentration data because of irregularities in composition, density, and water content in such samples. JRSO, therefore, presents these data as “intensities,” rather than concentration to ensure the user is aware of this fact.
The raw data files include a unit designation, but the user should disregard this and use the values as raw intensity data. 
One data column included in each data group is titled “LE” instead of an elemental symbol. This is the difference between the sum of the elemental data and 1,000,000 (1 million) presuming that the columns are in fact parts-per-million. This parameter, therefore, should only be used with a high amount of caution given that the values in the elemental columns are not calibrated.

Data File format

    Exp: expedition number
    Site: site number
    Hole: hole number
    Core: core number
    Type: type indicates the coring tool used to recover the core (typical types are F, H, R, X).
    Sect: section number.
    A/W: archive (A) or working (W) section half.
    Offset on section (cm): position of the observation made, measured relative to the top of a section half.
    Depth CSF-A (m): location of the observation expressed relative to the top of a hole.
    Depth [other] (m): location of the observation expressed relative to the top of a hole. The location is presented in a scale selected by the science party or the report user.
    Timestamp (UTC): time file was uploaded, which is typically a few minutes to hours after data were acquired.
    Run Main filename: name of the raw measurement file. Contains both samples and standards.
    Run SPM filename: name of the raw spectral file. Contains measurement spectrums and shot settings.
    [Element symbol]: alphabetically-sorted element symbols (e.g., Al, Fe) for each element’s raw data (unitless).
    Text ID: automatically generated unique database identifier for a sample, visible on printed labels.
    Test No: unique number associated with the instrument measurement steps that produced these data.
    Sample comments: observations recorded about the sample itself.
    Test comments: observations about a measurement or the measurement process; some measurement observations may be under Result comments.
    Result comments: observations about a measurement or the measurement process; some measurement observations may be under Test comments.