RARE EARTH ELEMENTS IN THE OFFSHORE SURFACE SEDIMENTS OF THE NORTHEASTERN ANTARCTIC PENINSULA AND THEIR IMPLICATIONS FOR PROVENANCE

Chemical analyses for rare earth elements have been carried out for a total of 36 samples taken from the surface sediments off the northeastern Antarctic Peninsula in order to study the the sources of sedimens. Data show that the REE concentrations of surface sediments, which ranges within 45.47~183.60×10^-6 and is 91.36×10^-6 on average, increase with fine-grained materials dominated by clay and decrease with biogenic silica. In the areas to the west of the line from the Joinville Island to the Elephant Island, including the Bransfield Strait and the shelf/slope of the South Shetland Islands, surface sediments are characterized by low REE concentrations, HREE enrichments, positive europium anomalies (δEu) relative to global shale average, and larger Sm/Nd molecular ratios, indicating that they were mainly derived from the South Shetland Islands where the Mesozoic/Cenozoic, in particular the Holocene volcanisms were active. In the eastern area, including the Powell Basin, the South Orkney Islands shelf and the South Scotia Ridge, the sediments have similar flat shale-normalized REE patterns, elevated LREE, weak positive europium anomalies (δEu) and smaller Sm/Nd molecular ratios while REE concentrations are controlled by clay and biogenic silica as well. It is inferred that the terrigenous components are derived mainly from the western and southern Weddell Sea, and secondarily from the South Orkney Islands, the South Scotia Ridge and the South Shetland Islands by ice-rafting and current transport.