IRON-RICH AMORPHOUS SEDIMENT FROM LOIHI SEAMOUNT

Red x-ray amorphous sediment was collected fran a dredge haul across the top of Loihi seamount, a recently active volcano southeast of the island of Hawaii.The sediment was examined using neutron activation analysis, x-ray diffraction and x-ray fluorescence.The sample contained 36.7%Fe, 19% H 2 0, 1.4% Ca, 1.0% P.0.07%Ti, and 0.1% AI.Minor element and rare earth element concentrations were low compared to typical marine sediments.The analyses were compared with those of sediments from the Galapagos Rise,East Pacific Rise, Red Sea brine pools, crystalline sediment fran Loihi, sediments fran the submerged parts of Fanu Wuhu and Thera volcanoes and typical pelagic clays.This Loihi sediment showed closest affinity to those sediments from active deep-sea hydrothermal vents.The FelP ratio and low rare earth element content suggest recent (possibly less than 40 yrs) deposi tion and contact with sea water.This is a rare example of such material at the site of active volcanism not associated with hydrothermal vents on ridge systems.