北太平洋中部赫斯海隆(Hess Rise)晚第四纪以来生源组分与粉尘输入的关系及其变化机制

Correlations Between Biogenic Components and Dust Input and Their Change Mechanism on Hess Rise,Central North Pacific,During the Late Quaternary

对海洋生产力的研究有助于理解大洋碳库的变化,粉尘输入则是影响海洋生产力的重要因子。对德国SO202-INOPEX航次在北太平洋中部赫斯海隆(Hess Rise)钻取的SO202-37-2孔0～251 cm沉积物样品进行了XRF元素扫描,碳酸钙、生物硅、有机碳、浮游有孔虫Globigerina bulloides和Globorotalia inflata氧碳同位素的综合分析,以期探讨该区域的生源组分特征及粉尘输入的变化历史。该孔的地层年代框架基于其浮游有孔虫G. inflata-δ^(18)O、G. bulloides-δ^(18)O与H3571孔G. inflata-δ^(18)O和深海氧同位素曲线LR04-δ^(18)O的对比。结果显示,该孔XRF-Ti/Ca值所代表的陆源粉尘输入强度变化与生物硅含量显著相关,指示粉尘输入刺激了海洋生产力的提高,并呈现出间冰期增强、冰期减弱的特点。究其原因,可能是由于冰期时西风带南移远离物源区,导致粉尘输出减少,西风急流的经向移动控制了该区域海洋生产力的变化。尽管冰期时全球粉尘输出是增多的,但是西风急流的位置变化使得该区域的粉尘沉积记录与其他地区不完全相同。

The study of marine export production is helpful to trace the changes of oceanic and global carbon reservoirs. Dust input is an important factor inspiring marine export production. Measurements of carbonate, Opal, TOC and Corg/N were performed on Core SO202-37-2, which was retrieved from Hess Rise, central North Pacific during the German SO202-INOPEX Expedition, for reconstructing variations of the local export production and dust input. The core age model is constructed via morphologically correlating its foraminifer oxygen isotope record with those of Core H3571 and the LR04 stack. XRF-Ti/Ca can be used as a proxy for dust input and its distribution pattern is consistent with that of Opal content, possibly indicating that dust input may have affected the local export production, i.e. the local export production increased (decreased) with enhancing (declining) dust input during interglacial (glacial) periods. Fluctuations in dust input might be due to southward/northward migration of the Westerly Jet over the dust source regions during interglacial and glacial periods. Although global dust output increased during glacial periods, meridional migration of the Westerly Jet in this area made the distribution pattern of the dust deposition in the study area different from that of other areas.