西カロリン海盆における過去30万年の有機炭素および無機炭素沈積流量の変遷

概要

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Sediment cores from the Caroline Basin were studied to reconstruct continuous 300, 000-year (300-kyr) records of inorganic and organic carbon accumulation rates. The pattern of variation in the accumulation rates shows that minimum values were observed at present and 100kyr, 200kyr and 280kyr ago. The fluctuations of inorganic carbon MAR (mass accumulation rate) were much larger than those of organic carbon MAR. The maxima of organic carbon MAR occurred in glacial Stages 8, 6, and the relative cold periods around Stage 2, while minima generally appeared in the interglacial periods. The fluctuation of organic carbon MAR was considered to result from the fluctuation of primary productivity and degree of preservation. The difference in MAR between the sedimentary inorganic and organic carbons (MARINORG-ORG) would provide a net carbon transfer between the ocean and the atmosphere during the formation of sedimentary particles. Comparison of MARINORG-ORG with the Vostok CO2 data showed that an increase of the CO2 concentration in the atmosphere was accompanied by high values of MARINORG-ORG in late Stages 6 and 1, whlie a gradual decrease occurred with small values of MARINORG-ORG in Stages 5 and 4. The only exception was the carbonate blume in early Stage 3. These results suggest that the formation of sedimentary inorganic and/or organic particles has involved the fluctuation of the CO2 concentration in the atmosphere.
日本第四紀学会の論文