赤道西太平洋晚第四纪古生产力变化: ODP 807A孔的记录

通过研究翁通-爪哇海台ODP807A孔顶部岩心微体古生物和有孔虫同位素的变化, 探讨冰期旋回中赤道西太平洋晚第四纪古生产力的变化.多种古生产力替代指标揭示出赤道西太平洋古生产力自深海氧同位素13期以来总体呈升高趋势, 具有冰期高、间冰期低的特征.温跃层替代指标显示该海域温跃层变化不具有简单的冰期-间冰期变化模式, 而是分为2个阶段: 280ka以前温跃层平均深度较浅, 呈现高幅低频波动; 280ka以后温跃层平均深度变深, 呈现低幅高频波动.古生产力和温跃层变化模式的明显差异说明温跃层变化不是赤道西太平洋表层生产力波动的主要原因.807A孔古生产力变化与西北太平洋风尘通量变化基本一致, 所以提出来自亚洲中东部的风尘对于提高赤道西太平洋生物生产力可能具有重要意义. 

Late Quaternary Variations of Productivity in the Western Equatorial Pacific Ocean: Records from ODP Hole 807A

Microfossil assemblages and foraminifer isotopes from the upper part of ODP Hole 807A on the Ontong Java plateau were studied to provide evidence for discussing Late Quaternary productivity variations with glacial cycles in the western equatorial Pacific. Multi-proxy results reveal that productivity gradually increased in general since marine isotope stage (MIS) 13, and was higher in glacial times than in interglacial times. The thermocline proxies do not completely fit into glacial-interglacial cycles, but present two stages of thermocline changes: shallower before 280 ka with higher amplitude and lower frequency abundance fluctuations; deeper after 280 ka with higher frequency and lower amplitude fluctuations. The distinct modes of variations between productivity and thermocline suggest that thermocline change is not a primary controlling factor of biological productivity in the western equatorial Pacific. As the fluctuations of paleoproductivity from Hole 807A match with dust flux records from the northwest Pacific, we propose that dust carried from east central Asian is likely to be more significant in enhancing biological productivity in the western equatorial Pacific.