Reconstructing the oceanic circulation and sediment source-to-sink patterns in the East China Sea during the past 30ka
Abstract
In the present study we try to reconstruct the oceanic circulation and sediment source-to-sink patterns during the past 30 ka in the East China Sea and adjoining delta area, based on organic, elemental and Sr-Nd isotopic geochemical compositions in the sediments from Core DGKS9604 from the middle Okinawa Trough and Core CM from the Changjiang Delta. The data show that the Changjiang-derived sediments played an important role in the formation of sedimentary strata in the marginal sea, albeit with variable influences during the Marine Isotope Stage 3, Last Glacial Maximum and early Holocene. The Taiwan Island-derived terrestrial sediments transported by the Kuroshio Current might dominate the middle Okinawa Trough during the mid-late Holocene. Organic matters accumulated in the Changjiang Delta are primarily derived from terrestrial C3 plant, whereas marine organic matter dominated in the middle Okinawa Trough. Geochemical compositions also revealed the rapid climate changes over the past 30ka, which is comparable with other sedimentary and palaeoceanographic records elsewhere. In particular, the combined influences of natural climatic variability, sea-level changes and anthropogenic activities on the production, transport, deposition and preservation of terrestrial sediment and organic matter in the Changjiang Delta and adjoining East China Sea were recognized. The changes of the Kuroshio Current mainstream over the past 30 ka greatly regulated the dispersal patterns of terrestrial sediments sourced from the surrounding landmasses, producing unique sedimentary architecture in the delta area and marginal sea. It should be cautious to make a comprehensive comparison of paleoenvironmental records in the delta and East China Sea due to the intense land-sea interaction and widespread discontinuity in the late Quaternary sedimentary strata of the Changjiang Delta. The present study shed new light on the paleoenvironmental reconstruction of East Asian marginal seas, especially in relation to the land-sea interactions during the late Quaternary.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMPP33C1568Y
- Keywords:
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- 4825 Geochemistry;
- 4835 Marine inorganic chemistry (1050);
- 4860 Radioactivity and radioisotopes;
- 4863 Sedimentation (1861);
- 4924 Geochemical tracers