初探6700年来格陵兰西部海域硅藻组合与环境变迁

发布时间：2019-06-25 15:06

【摘要】：不同尺度的气候研究日益成为古气候、古环境恢复的热点,地处中高纬、靠近格陵兰冰盖的北大西洋海域一直是近几年来研究的重点。本文根据西格陵兰海域连续沉积钻孔GA306-GC3(后面简称为GC3孔),发现该孔中的硅藻能直观反映中晚全新世以来西格陵兰海域古海洋环境变化及其主要影响因子。对GC3孔中的硅藻进行前期处理、制片和鉴定,通过对89个玻片鉴定发现沉积物中硅藻含量十分丰富,总计鉴定出107种硅藻,其中常见硅藻主要包括：Bacterosira bathyomphala、Fragilariopsis cylindrus、Fragilariopsis oceanica、 Thalassionema nitzschioides、Thalassiosira antarctica var. boreal休眠孢子、 Thalassiosira nordenskioeldii、Thalassiosira oestrupii、Rhizosolenia hebetata f. semispina、Rhizosolenia borealis和Thalassiosira hyalina等。运用古环境分析专业软件Tilia和C2对硅藻数据进行聚类分析和主成分分析,发现两者结果间存在很好的一致性,自上而下还将硅藻划分出相同的组合带,共同反映了该地区6700年以来气候逐渐变冷的过程,具体变化过程主要包含以下3个阶段： 6650—3950cal. a BP期间暖水硅藻含量丰富且活跃,表层海水温度较高,为全新世大暖期,后期大西洋暖水对该区域的影响有所减弱,气候逐渐转冷,暖水种含量呈小幅减小,冷水种含量随之波动上升,标志着暖期结束。 3950—1650cal.a BP期间硅藻含量变化强度明显高于上一阶段,尤其以3000a.BP为界,前期由于印明格暖流影响增加,暖水种硅藻含量波动增加。3000—1650a.BP期间因受寒流影响,而极地、海冰种含量大幅增加。 1650—130cal. a BP期间因寒流影响继续加强,暖水硅藻含量降至极小值,海冰和极地硅藻始终高值震荡,但在1000cal. a BP前后极地种和海冰种含量突然降至低值,可能与中世纪暖期有关。 GC3孔化石硅藻记录不仅与邻近格陵兰岛上的冰芯记录(GSIP2)温度曲线间存在良好的对应关系,同时还与相邻区域其他资料对比也有很好的一致性,这些资料共同记录了该北半球中高纬地区中晚全新世以来的降温趋势,同时还反映出几次典型气候变化事件(如全新世大暖期、黑暗时代冷期、中世纪暖期、小冰期等)。
[Abstract]:The climate research of different scales has become the hot spot of the ancient climate and the restoration of the ancient environment, and the North Atlantic sea area close to the Greenland ice cover has been the focus of the research in recent years. According to the continuous deposition of G306-GC3 (hereinafter referred to as the GC3 hole) in the West Greenland sea area, it is found that the diatoms in this hole can directly reflect the changes of the ancient marine environment and its main influencing factors in the West Greenland sea area since the Holocene. The diatoms in the GC3 wells were pre-treated, tabletted and identified, and a total of 107 diatoms were identified by the identification of 89 slides, including: Bacterosira baathyomphala, Fragilariopsis cylindus, Fragilariopsis ocellica, Thalassiona nitzschioides, Thalassirosira antarctica va. r. Boreal dormant spores, Thalassiosira nodenskoeldii, Thalassiosira oesupii, Rizzosolenia heteata f. semispinina, Rizzosolenia borneis and Thalassiosira hyalina Based on the analysis of the cluster analysis and the principal component of the diatom data by the ancient environment analysis professional software, Tilia and C2, it is found that there is a good agreement between the two results, and the diatom is divided into the same combination zone from top to bottom, which reflects the gradual cooling of the climate since 6700 years in the region. the process of the specific change mainly comprises the following three steps: Stage:6650-39 During the period of 50 cal. a BP, the content of the warm water is rich and active, the temperature of the surface sea water is high, the influence of the warm water in the late Atlantic on the region is weakened, the climate is gradually cooled, the content of the warm water is small, and the content of the cold water is increased and the mark At the end of the warm-up period, the change of diatom content during the period of 3950 to 1650 cal. a BP is obviously higher than that of the previous stage, especially at the boundary of 3000a. BP, and the fluctuation of the content of the diatom in the warm water is increased due to the influence of the warm-flow of the Inmin.3000-1650a. BP, which is affected by the cold flow during the BP, and the polar and sea-ice. A significant increase in the content of species. During the period of 50 to 130 cal. a BP, due to the influence of the cold flow, the content of the warm water diatom is reduced to the minimum value, and the sea ice and the polar diatoms always oscillate at high value. however, that content of the polar species and the sea ice before and after 1000 cal. a BP is suddenly reduced to a low value, The GC3-hole fossil diatom record not only has a good correspondence with the ice core record (GSIP2) temperature curve on the adjacent Greenland island, but also the other resources of the adjacent area The comparison of materials also has good consistency, which together record the cooling trend of the middle and high-latitude regions in the Northern Hemisphere since the Holocene, and also reflects several typical climate change events, such as the new world of the world and the cold period of the dark times.
【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P532;P736.22

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