白令海北部陆坡晚第四纪的古海洋与古气候学记录

白令海北部陆坡B2 9柱状样中放射虫Cycladophoradavisiana含量曲线和深海SPECMAP氧同位素记录的对比 ,为该柱状样建立了晚第四纪约 1 0万年以来的地层年代框架。该柱状样中微体化石、碳屑颗粒、筏冰碎屑 (石英和岩屑颗粒 )的定量分析结果表明 ,作为表层生产力指标的粗组份自氧同位素 5 .3期以来呈阶梯状增加 ,反映表层生产力阶段式的增长 ;碳屑颗粒丰度自氧同位素 5 .3期至末次冰消期的增加说明白令海末次冰消期以前气候较全新世干冷 ,天然火灾发生的概率较全新世大大增加 ;冰期和早、中全新世较高的筏冰碎屑反映了冰期和早、中全新世白令海陆架海冰的扩大以及气候转暖所导致的海冰消融的过程 ,揭示了白令海对过去全球气候变化的响应。

LATE QUATERNARY PALEOCEANOGRAPHIC AND PALEOCLIMATOLOGIC RECORDS ON THE SLOPE OF THE NORTHERN BERING SEA

A Late Quaternary stratigraphic and chronologic (over the last 100ka) framework is established for Core B2-9 on the slope of the northern Bering Sea, based on correlation of Cycladophora davisiana (radiolarian) content in this core with SPECMAP oxygen isotopic records from deep-sea sediments. Quantitative analytic results of microfossil, charcoal debris and ice-rafted detritus (quartz and lithic grains) in this core indicate that coarse fraction, served as a proxy of surface productivity, increased step by step during the MIS 5.3, reflecting phasic enhanced surface productivity. High abundance of charcoal debris from the MIS 5.3 to deglaciation reveals that the climate in the Bering Sea before deglaciation was drier and colder than that during the Holocene and the occurred natural fire probability heightened much more than that during the Holocene. Ice-rafted detritus (>0.154 mm quartz and lithic grains) increased during the glacial periods and early to middle Holocene indicates that sea ice volume on the shelf of the northern Bering Sea during the periods extended and melted, induced by later warm climate, opening out the Bering Sea responses to past global climate change.