LATE QUATERNARY PALEOCEANOGRAPHIC RECORDS IN THE SOUTHERN OKHOTSK SEA

鄂霍次克海是太平洋第二大边缘海,在西北太平洋水文环境中扮演重要角色。综合分析了鄂霍次克海南部T00孔沉积物的多种替代性指标,揭示了鄂霍次克海晚第四纪以来的环境变化受季节性海冰变化、大气循环模式、陆源物质通量和表层生产力的共同影响。对比放射虫CyClAdOPHOrA dAVISIAnA的含量曲线与lr04氧同位素记录,该孔沉积物可划分为氧同位素1-7期,底部年龄约为250kA。C.dAVISIAnA在间冰期的高含量表明鄂霍次克海中层水是北太平洋中层水的主要源区。蛋白石和有机碳的分析显示鄂霍次克海表层生产力在冰消期突然增大,随后在间冰期逐渐下降,冰期普遍较低。C/n比值曲线的分析说明鄂霍次克海的有机质沉积物主要来源于海洋。沉积物粒度的分析揭示鄂霍次克海冰期时陆源粗颗粒含量较低,至冰消期粗颗粒含量突然增加,而在间冰期陆源粗颗粒含量较高。The Sea of Okhotsk is the second largest marginal sea of the Pacific,and plays a significant role in the hydrology of the northwestern Pacific.We processed and analyzed multi-proxies of the sediment of core T00 from the southern Sea of Okhotsk.The results show that the environmental changes in the Sea of Okhotsk are characterized by a coupled interplay between seasonal sea ice dynamics,atmospheric circulation patterns,terrigenous flux,and surface productivity during late Quaternary.The stratigraphic MIS1 to MIS7 since--250 ka of core T00 has been recognized by comparing the percentage curve of Cycladophora davisiana with the LR04 benthic δ18O stack.The higher percentage of C.davisiana during interglacial intervals indicates that the Sea of Okhotsk is the source region of the North Pacific Intermediate Water Mass.The primary productivity in the southern Sea of Okhotsk,indexed by contents of opal and total organic carbon,is relatively higher during interglacials than during glacials,and increases rapidly during deglacials.The oceanic origin of the organic matters in core T00 is figured out by the C/N ratio analysis.The content of terrigenous coarse grain in the Sea of Okhotsk is lower in glacials than in interglacials and increases rapidly in deglacials.国家重点基础研究发展规划项目(G2007CB815903);国家自然科学基金项目(40321603;40676030;40576029);高等学校博士学科点专项科研基金(20040247028

Biogenic and terrigenous coarse fractions in surface sediments of the western Arctic Ocean and their sedimentary environments

通过中国第1至第3次北极科学考察在北冰洋西部所采集的99个表层沉积物中生源与陆源粗组分的分析,研究了该海域表层生产力的变化,有机质来源以及陆源粗颗粒物质的输入方式和影响因素。研究区域生源组分所反映的表层生产力变化与通过白令海峡进入楚科奇海的3股太平洋洋流密切相关。楚科奇海西侧高盐高营养盐的阿纳德尔流流经区域,表层生产力普遍较高;东侧低盐低营养盐阿拉斯加沿岸流流经区域,浮游硅质生物生产力低,并且受陆源有机质输入影响显著。阿尔法脊和楚科奇海台较高的浮游钙质生物生产力与北大西洋水的注入密切相关。楚科奇海陆架区低的浮游钙质生物生产力与陆源物质的稀释作用和浮游钙质生物生活水深有关;加拿大海盆区低的浮游钙质生物生产力主要受到碳酸钙溶解作用的影响。研究区域表层沉积物中的陆源粗组分-冰筏碎屑(ICE-rAfTEd dETrITuS,Ird)的分布主要受海冰和冰山的搬运,陆缘冰输入,河流输入以及太平洋入流水的影响。白令海峡入口处的陆源粗颗粒沉积主要受太平洋入流水影响;阿拉斯加近岸海域的陆源粗颗粒沉积来自于陆缘冰以及河流的输入;而北风脊高的Ird含量主要是由海冰和冰山所携带,被波弗特环流搬运至此,伴随着海冰和冰山的融化并卸载进入沉积物中。Biogenic and terrigenous coarse fractions in the surface sediments from the western Arctic Ocean,which were collected in the First,the Second and the Third Chinese National Arctic Expeditions,were measured by different means in this paper,revealing the surface productivity changes,source of organic matter and input patterns of terrigenous coarse matters in the study area.The surface productivity indicated by the biogenic sediments in the area is closely related to the three Pacific Ocean currents entering into the Chukchi Sea through Bering Strait.High surface productivity in the western Chukchi Sea is resulted from the hyperhaline and hypertrophic Anadyr Stream,whereas low planktonic siliceous productivity in its eastern part is caused by the hypohaline and hypotrophic Alaska Coastal Stream.High planktonic calcareous productivity in the Chukchi Sea Plateau and Alpha Ridge is ascribed to the impact of the northern Atlantic water mass.Low planktonic calcareous productivity in the Chukchi Sea shelf is attributed to the terrigenous matter dilution and life depth of calcareous microorganism.Low calcareous planktonic productivity in the Canada Basin is responded to the strong CaCO3 dissolution.Distribution of terrigenous coarse fraction(ice-rafted detritus-IRD) in the western Arctic Ocean is influenced mainly by sea ice and iceberg transport,terrestrial ice input,river and Pacific currents.The terrigenous coarse fraction in the Bering Strait is impacted by the Pacific currents entering into the Chukchi Sea through Bering Strait.The terrigenous coarse fraction near Alaska coastal area is transported by the terrestrial ice and river.The high IRD in the Northwind Ridge is contributed by the massive sea ice and icebergs conveyed by the Beaufort Circulation,and deposited at the seafloor when the sea ice and icebergs melt.国家重点基础研究发展规划项目(G2007CB815903);国家自然科学基金重点项目(41030859);中国第3次北极科学考察以及国际极地年中国行动计划资助项目;中国地质调查局项目(水[2010]矿评03-06-04