Data report: calibration of XRF-estimated CaCO3 along the Site U1338 splice: Expedition 320/321

Abstract

We combined X-ray fluorescence (XRF) scan data from Integrated Ocean Drilling Program Expedition 321 Site U1338 and a set of 1060 discrete CaCO3measurements to calibrate a high-resolution XRF-estimated CaCO3 profile for Site U1338. In this data report, we describe the method of calibration, using normalized median-scaled XRF data and discrete CaCO3 measurements. A subset of ~¾ of the discrete measurements was used to calibrate the XRF scan, and the quality of the calibration was checked with the remainder of the discrete data. Based upon the check data, the calibrated XRF CaCO3 estimate is within ±5% of the independent discrete measurements (1 standard deviation). The calibrated XRF CaCO3 estimate provides, for the first time, a carbonate profile for the middle Miocene–Holocene with a resolution of ~2 k.y. for the uppermost 60 compressed meters composite depth below seafloor and ≤1 k.y. resolution in the rest of the sediment section.