CONCENTRATION OF HEAVY GRAINS IN THE CORE CATCHER SAMPLES OF MID EOCENE TO LATE PLEISTOCENE SEDIMENTS FROM THE LOMONOSOV RIDGE, ARCTIC OCEAN

Sediments recovered by Integrated Ocean Drilling Program (IODP) expedition 302 from the Lomonosov Ridge in the Arctic Ocean appear to contain concentrations of heavy grains in the core catchers portions. Unpublished results by members of the scientific party suggested that metallic microspheres and fish teeth are more abundant in the core catcher samples through out the core. These initial observations have prompted our further examination of the core catcher samples to determine if heavy grains occur in abundance in both the >250 um and 150 um to 250 um size fractions of core catcher samples. These heavy grains refer to mafic minerals, weathered and non weathered metallic fragments, siderite, rhodochrosite, and cosmic spheroids. Whether or not there are increased concentrations of heavy grains in the core catcher samples is significant because it has direct implications for any study using downcore comparison of sediment grain size and composition, such as the reconstruction of ice rafted debris abundance histories. To date, our visual observations indicate that such heavier grains are consistently more abundant in the core catcher samples then in other samples of the drill core. Ongoing SEM and elemental analyses are used to help characterize the texture and composition of these grains. The mechanism which caused the abundance of the heavy grains in the core catcher portions of samples is likely related to the drilling operations.