Carbonate-free basis chemical composition of sediments from the Bauer Deep

Sediment cores of the Bauer Deep were obtained by standard piston-coring techniques on cruises of the R/V Atlantis II (no. 54) and R/V Chain (no. 100) of the Woods Hole Oceanographic Institution. The sediment samples we analyzed were obtained by taking 1- to 10-cm sections from the center of the split cores. All samples were rinsed to remove sea salt, ground under acetone, and sieved through a nylon screen (200 mesh). The sieved samples were split into separate portions for bulk chemical analysis, CaCO3 determination, and x-ray diffraction where this was deemed useful. CaCO3 was determined by 0.2 M acetic acid leach at 50°C for 2 hrs. Residual Ca was determined by atomic absorption as well as Mg, Na, K, Fe and Mn. The data suggest tha a small but detectable amount of Fe is leached in excess of that occuring in the ferromanganese compounds. This may originate either in an iron oxyhydroxlde phase containing no Mn or through leaching of the Fe montmorillonite.