中全新世以来东西伯利亚陆架沉积物来源的演化:元素地球化学记录

Provenance evolution since Middle Holocene of the sediments on the East Siberian shelf: Evidence from elemental geochemistry

北极地区对全球气候变化非常敏感,是研究古环境和古气候变化的关键区域。东西伯利亚海作为北极重要的边缘海之一,对东西伯利亚陆架和陆坡沉积物来源的研究将有助于加深对北极沉积环境和气候变化的认识。本文通过对东西伯利亚海西部LV77-36岩心沉积物中碎屑组分的主微量、稀土元素进行分析,阐述了各指标随年代的变化特征,并探讨了中全新世以来东西伯利亚海西部碎屑沉积来源的变化及其对古环境演变的响应。结果表明中全新世以来LV77-36岩心沉积物主要来源于勒拿河、因迪吉尔卡河、亚纳河和马更些河的河流输入,以及西伯利亚地台和新西伯利亚群岛的海岸侵蚀物质。与其他古气候参数对比发现,海冰和洋流的变化对源区物质在东西伯利亚陆架的分散和沉积有着重要的影响。全新世晚期由于楚科奇海海冰的增加、西伯利亚沿岸流的减弱和波弗特环流的增强,导致北美端元的物质贡献相较全新世中期有小幅度增加。

The Arctic region is very sensitive to global climate change.It is a key area in the world to the study of paleoenvironmental and paleoclimatic changes.The East Siberian Sea(ESS)is one of the important marginal seas in the Arctic region.Study of the sediment provenance of the ESS shelf is essential to the overall understanding of the Arctic environmental and climatic changes.Based on the analyzing results of the major,trace and rare earth elements from the core of LV77-36,this paper described the change patterns of concerned indices with time,discussed the variation of detrital components in the ESS sediments since Middle Holocene,and finally,revealed the response of provenance evolution to paleoenvironment changes.The results show that since Middle Holocene,the sediments of the core LV77-36 are mainly coming from the suspended materials carried by the Lena,Indigirka,Yana and Mackenzie rivers,in addition to the coastal erosive materials from the Siberian platform and New Siberian Islands.According to the Comparison with other paleoclimatic parameters,it is found that the changes of sea ice and ocean currents have important effects on the dispersion and deposition of sediments on the East Siberia shelf.In Late Holocene,due to the increase in sea ice in the Chukchi Sea,the weakening of the Siberian coastal current and the strengthening of the Beaufort circulation,the material contributed by the North American end member increased slightly compared to the Middle Holocene sediments.