Data report: X-ray fluorescence studies of Site U1457 sediments, Laxmi Basin, Arabian Sea

Abstract

Bulk sediment chemistry was measured at 2 cm resolution along cores from International Ocean Discovery Program (IODP) Site U1457 using the X-ray fluorescence (XRF) core scanner at the IODP Gulf Coast Repository. The Pleistocene splice section assembled from Holes U1457A and U1457B was scanned in its entirety, and nearly continuous sediment bulk chemistry profiles were constructed to a depth of 125 m core composite depth below seafloor (CCSF). Some sections of Hole U1457C were also scanned: (1) an upper Miocene hemipelagic section and (2) a 30 m lower Paleocene section directly overlying basalt. In the Pleistocene spliced sections, 2 cm spacing represents a sampling resolution of 150–300 y, whereas in the upper Miocene section this spacing represents about 500 y between samples. We report data and acquisition conditions for major and many minor elements. We find large variability in CaCO3 content in the Pleistocene section, from around 14 to 89 wt%. We used discrete shipboard CaCO3 measurements to calibrate the XRF Ca data. CaCO3 has cyclic variability and correlates with light sediment colors. Variation in aluminosilicate elements is largely caused by changes in dilution by CaCO3. The lower part of the spliced section, presumably representing distal Indus Fan deposits, has a distinctive but more uniform composition than the upper part.