Quantitative analytic results of the biogenic components in Core B2-9 fromthe northern Bering Sea slope indicate that the coarse fraction and opal content, serving as proxiesof surface productivity, have increased ste...Quantitative analytic results of the biogenic components in Core B2-9 fromthe northern Bering Sea slope indicate that the coarse fraction and opal content, serving as proxiesof surface productivity, have increased stepwise since the marine isotope stageCMISJS.S, reflectingperiodic enhancement in surface productivity.The surface productivity attained its highest levelduring the Holocene, followed by MIS 3.2 to 2 and then MIS 5.3 to 3.3 with a lowest level. Hightotal organic carbon(TOC) contents, together with high C/N ratios, which stand mostly between 7 and20, show that the TOC was deposited from mixing sources. Therefore,one has to be cautious to use TOCas a proxy of surface productivity.The high TOC and C/N ratio during MIS 5.1, 3.3 to 3.2 and theHolocene reflect that the terrigenous organic matter input increased during interglacialperiods.Increases in the fine- and silt-grained terrigenous components from MIS 5.3 to the middleHolocene imply that with the cooling climate, sea ice on the Bering Sea slope extended continuously.Ice-rafted and charcoal detritus increased during glacial, interstadial and the last deglaciationperiods and decreased during interglacial periods, suggesting that sea ice on the slope increasedand melted, respectively, during glacial and interglacial periods. The extension of sea ice duringglacial periods.which was linked with the climate over the North American Continent, responded toglobal climate change during late Quaternary glacial and interglacial cycles.展开更多
基金supported by the National Key Basic Research Special Foundation Pro-gram of China under contract No.G2000078500the National Natural Science Foundation of China under contract Nos 40321603,40276020 and 40176015the Foundation for the Author of National Excellent Doctoral Dissertation of China under contract No.200126.
文摘Quantitative analytic results of the biogenic components in Core B2-9 fromthe northern Bering Sea slope indicate that the coarse fraction and opal content, serving as proxiesof surface productivity, have increased stepwise since the marine isotope stageCMISJS.S, reflectingperiodic enhancement in surface productivity.The surface productivity attained its highest levelduring the Holocene, followed by MIS 3.2 to 2 and then MIS 5.3 to 3.3 with a lowest level. Hightotal organic carbon(TOC) contents, together with high C/N ratios, which stand mostly between 7 and20, show that the TOC was deposited from mixing sources. Therefore,one has to be cautious to use TOCas a proxy of surface productivity.The high TOC and C/N ratio during MIS 5.1, 3.3 to 3.2 and theHolocene reflect that the terrigenous organic matter input increased during interglacialperiods.Increases in the fine- and silt-grained terrigenous components from MIS 5.3 to the middleHolocene imply that with the cooling climate, sea ice on the Bering Sea slope extended continuously.Ice-rafted and charcoal detritus increased during glacial, interstadial and the last deglaciationperiods and decreased during interglacial periods, suggesting that sea ice on the slope increasedand melted, respectively, during glacial and interglacial periods. The extension of sea ice duringglacial periods.which was linked with the climate over the North American Continent, responded toglobal climate change during late Quaternary glacial and interglacial cycles.
