Data report: sediment major element, minor element, and reactive iron and manganese data from the Okinawa Trough: IODP Expedition 331 Sites C0014 and C0017

Abstract

We present sediment solid-phase chemical data from Integrated Ocean Drilling Program Expedition 331 Sites C0014 and C0017, two sites with contrasting sediment chemistries. Results presented here include a suite of major and trace elements from whole-sediment digestions and sediments extracted using a selective leaching procedure for Fe and Mn. The sediment package at Site C0014 is chemically variable, displaying a wide range of concentrations for a number of major and trace elements. This sediment package has intervals rich in solid-phase Mg, with values as high as 10-15 wt% between ∼30 and 38 meters below seafloor (mbsf) and lower values at shallower depths and deeper than ∼40 mbsf. This pattern is consistent with other expedition data, suggesting a sedimentary zone of active high-temperature alteration centered roughly between 30 and 40 mbsf. The upper sedimentary package is also rich in dithionate extractable iron, which decreases to low values by ∼30 mbsf. Unlike iron, dithionate extractable Mn is relatively low in the upper 20-30 m of sediment, with some enrichment in the uppermost sediment package for Holes C0014G and C0014B. Below this region, however, a zone of enriched reactive and total Mn is centered just above ∼40 mbsf. In contrast to Site C0014, Site C0017 generally lacks the more pronounced chemical signatures apparent within the sediments, and many of the chemical signatures likely reflect the regional background hemipelagic sediment cover. There are, however, elevated levels of reactive Mn both in the upper ∼30 m and the bottom ∼50-75 m of sediment.