HR: 1340h
AN: PP23A-1393    [Abstracts]
TI: Detrital Sediment Supply And Late Quaternary Environmental Changes Off Taiwan, ODP Site 1202
AU: Hofmann, J
EM: hofmann-jana@web.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AU: * Diekmann, B
EM: bdiekmann@awi-potsdam.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 600149, Potsdam, 14473 Germany
AU: Henrich, R
EM: henrich@uni-bremen.de
AF: Bremen University, Geoscience Department, P.O.Box 330440, Bremen, 28334 Germany
AU: Roehl, U
EM: uroehl@allgeo.uni-bremen.de
AF: Bremen University, Geoscience Department, P.O.Box 330440, Bremen, 28334 Germany
AU: Fuetterer, D K
EM: dfuetterer@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, P.O.Box 120161, Bremerhaven, 27515 Germany
AB: During Leg 195 of the Ocean Drilling Program, Site 1202 was drilled in the subtropical northwestern Pacific Ocean beneath the Kuroshio ("Black Current") between northern Taiwan and the Ryukyu Island Arc on the northern flank of the Ilan Ridge at 1275 m water depth. The ridge separates the southwestern end of the Okinawa Trough from the basins of the Philippine Sea. The upper 120 m of the Site 1202 section, composed of dark grey calcareous silty clay, provide a high-resolution record of the last 30 kyr, deposited at high sedimentation rates between 3.0 and 5.0 m/kyr and peak values of 9,0 m /kyr between 15.5 and 11 ka. Variations in the modes and sources of detrital sediment input, as inferred from sediment granulometry, mineralogy, and element-scanner data, reflect complex changes in environmental boundary conditions related to postglacial sea-level rise, monsoon climate, tectonics, and Kuroshio variability. Between 30 and 11 ka, low portions of sortable silt show that the Kuroshio did not enter the Okinawa Trough because of low sea level. Clay-mineral tracers point to increased sediment supply from mainland China by the discharge of Yangtze sediments directly across the East China Shelf edge into the Okinawa Trough. Consistent with maximum sedimentaion rates, Yangtze discharge reached a maximum between 15.5 and 11.0 ka. High fluvial sediment supply apparently was triggered by both postglacial sea-level rise and strengthened summer monsoon in response to precessional forcing of insolation. The Holocene was dominated by sediment supply from Taiwan since 11 ka, as indicated by clay-mineral tracers and geochemistry. High proportions of sortable silt point to strong bottom currents, mediated by sea-level rise and enhanced Kuroshio activity at Site 1202. Element-scanner data reveal the presence of 200-yr cycles, possibly related to short-term climate perturbations.
DE: 9355 Pacific Ocean
DE: 9604 Cenozoic
DE: 4267 Paleoceanography
DE: 3022 Marine sediments--processes and transport
DE: 3309 Climatology (1620)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting