Aquatic Sciences Meeting, Albuquerque 2001

PC03 Undergraduate Education

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Wallace, K, , Brown University, Providence, USA, Kali_Wallace@brown.edu

Lin, J, , Woods Hole Oceanographic Institution, Woods Hole, USA, jlin@whoi.edu

EVIDENCE FOR RAPID CHANGES IN SEDIMENTATION RATES ON THE SOUTH CHINA SEA MARGIN: CONNECTIONS TO SEAFLOOR SPREADING AND PALEO-ENVIRONMENTAL CHANGES

The sediments in the South China Sea (SCS) margins contain a valuable record of the history of rifting, seafloor spreading, and the East Asian monsoons. We have analyzed logging data and seismic reflection profiles near Sites 1146 and 1148 of the 1999 ODP Leg 184 cruise to: (1) identify and date prominent seismic reflectors; (2) trace the lateral extent of each reflector; (3) calculate the sedimentation rate between successive reflectors; and (4) determine the regional variability of sedimentation rates. Analysis of Site 1148 showed rapid rates (150-200 m/My) during the onset of seafloor spreading at 30-31 Ma, followed by a period of slower rates beginning at 23 Ma (>50 m/My). At ~ 2-3 Ma, the sedimentation rates increase to as much as 200-250 m/My. Comparison with Site 1146 and independent data from the Pearl River basin suggests that rapid sedimentation was widespread over the northern SCS margin during 28-30 Ma and since 2-3 Ma. Because there are no obvious tectonic causes for the second period of rapid sedimentation, the East Asian monsoon and other environmental factors are being investigated.

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Aquatic Sciences Meeting, Albuquerque 2001

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