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We used XRF measurement of Ca peak area and discrete CaCO3 analyses from Site U1338 to calibrate a high-resolution CaCO3 profile along the Site U1338 splice. Data spacing of 2.5 cm results in analyses at ~2 k.y. age spacing from 0 to 58 cmcd (0 to 4.65 Ma) and ~ 1 k.y. spacing or less below, from 4.65 to >16 Ma. By comparing discrete data, XRF data, and the GRA bulk density profile, we find that the high-resolution XRF profile represents changes in sedimentary CaCO3 content and not measurement variability. We find that the XRF CaCO3 estimate is typically within 5% of the discrete measurements, but that there is a minor depth-related bias to the XRF CaCO3 estimate. This new high-resolution CaCO3 profile will allow further work to probe the changes in the Neogene carbon cycle.