| 摘要: |
| 对鲍威尔海盆D3-5柱样的156个沉积硅藻样品进行分析，鉴定出硅藻54个种和变种，以海水种和冷水种为主。通过硅藻分析，将晚更新世以来鲍威尔海盆的海洋环境变化划分为以下几个期间：58.6-72.5 ka BP期间，硅藻以冷水种和海冰种为主，并出现沿岸种，推测因南极冰盖增长，鲍威尔海盆受极地冷水团控制，气候出现明显冷-暖交替，而且海平面较低，站位水深较浅。40.7-58.6 ka BP期间，出现明显气候冷-暖转变，海洋环境受气候变化影响较大，变得不稳定，由于海冰融化、温盐循环加强和冰筏碎屑事件的频发导致硅藻种类、丰度骤减。26.2-40.7 ka BP期间，硅藻种类明显增加，出现海冰种，冷水种增加，推测处于末次冰盛期的冰盖增长前期，中纬度暖水团在南极海区的影响范围向南扩大，冷、暖水团强烈混合，驱动温盐循环。26.2 ka BP至今，硅藻丰度增加，极地冷、暖水团混合的指示种Fragilariopsis oceanica，指示研究区的表层与底层水体混合增强，海冰覆盖面积持续增大，威德尔环流势力增强，中纬度暖水势力减弱。总体来说，自晚更新世以来鲍威尔海盆经历了冷期（南极冰盖发育）—暖期—冷期（末次冰盛期）的阶段转变，而在MIS 3阶段中存在一段较长时间的冰筏碎屑事件时期。 |
| 关键词: 硅藻 鲍威尔海盆 沉积柱样 海洋环境 |
| DOI： |
| 分类号: |
| 基金项目:福建省自然科学基金计划项目，2023J011378号；南极重点海域对气候变化的响应和影响项目，IRASCC2020-2023-01-03-02号，IRASCC2020-2023-01-02-03号 |
|
| Characteristics and environmental implications of fossilized diatom assemblages of the D3-5 column sample in the Powell Basin since the late Pleistocene |
|
Chen Min,Lin Yanting,Wang Feng,Li Yunhai,Liu Xuan,Li Jiayu,Huang Qing
|
|
1.College of Marine Living Resource Sciences and Management, Shanghai Ocean University;2.Third Institute of Oceanography, Ministry of Natural Resources
|
| Abstract: |
| 54 species and variants of diatoms dominated by seawater and cold-water species were identified during the analysis of 156 sedimentary diatom samples from the Powell Basin D3-5 column sample. The following stages of the changes of the Powell Basin marine environment since the Late Pleistocene were established based on diatom analysis. During the 58.6-72.5 ka BP period, diatoms were dominated by cold-water and sea-ice species, and coastal species appeared. It was speculated that due to the growth of the Antarctic ice-sheet, the Powell Basin was under the control of polar cold-water mass, and the climate had a significant cold-warm transition. Besides, the sea level was low and the water depth is shallow. During the 40.7-58.6 ka BP period, there was an obvious climate cold-warm change. The marine environment was greatly affected by climate change and becomes unstable. It was inferred that the melting of sea ice, the strengthening of thermohaline circulation and the frequent occurrence of Ice-rafted detritus events, the species and abundance of diatoms decreased sharply. In the 26.2-40.7 ka BP period, the diatom species increased significantly, and the sea-ice appeared and cold-water species increased. It was speculated that in the early stage of ice-sheet growth of the Last Glacial Period, the influence range of the mid-latitude warm water mass in the Antarctic Sea area expanded southwards, and the cold and warm water masses were strongly mixed to drive the thermohaline circulation. From 26.2 ka BP to the present, the abundance of diatoms has increased, and the occurrence of diatom species Fragilariopsis oceanica indicating mixed with polar cold and warm water, suggesting that the mix of surface and bottom water in the study area enhanced. Besides, the sea-ice coverage area has continued expanding, the power of Weddell Circulation enhanced, while the power of mid-latitude warm water decreased. On the whole, the Powell Basin had undergone a stage transition from the Cold Period (development of the Antarctic Ice Sheet) to the Warm Period then to the Cold Period (the Last Glacial Period) since the Late Pleistocene, and there was an extended period of Ice-rafted detritus events in the MIS 3 stage. |
| Key words: diatom Powell Basin sedimentary column marine environment |