论文部分内容阅读
通过对福建仙山泥炭钻孔中正构烷烃的分析,探讨了研究区近千年以来的气候特征。分析显示:正构烷烃分布范围主要为C_(16)~C_(35),且以奇碳链为主,奇偶优势明显。正构烷烃与有机质含量(TOC)密切相关,在典型的泥炭层,TOC含量高,长碳链的C_(27),C_(29)和C_(31)正构烷烃占优势,揭示有机质主要来源于草本或木本等高等植物,盆地处于相对干的沉积环境;在非泥炭层,TOC含量低,钻孔中多含粗砂或粉砂,中碳链的C_(21)或C_(23)正构烷烃占优势,揭示有机质主要来源于水生植物或苔藓植物,表明相对较湿的沉积环境。钻孔中正构烷烃C_(23)/C_(27)比值与前人提出的C_(23)/C_(29)和P_(aq.)等参数呈同向变化,可以作为区域干-湿变化的代用指标。结合地层的年代序列,利用正构烷烃重建了区域距今1400年以来的植被演化和气候变化历史。结果显示,福建仙山地区气候存在3次相对湿润和4次相对较干的时段。在钻孔358~280cm(约公元600~910年),气候相对较干,在280~40cm(约公元910~1640年),降水较多,气候湿润,但中间存在两次变干的阶段;在40~0cm(约公元1640年至今),降水相对较少,气候转干。TOC含量和正构烷烃C_(23)/C_(27)序列与南方旱涝频率序列、石笋和硅藻记录对比显示,研究区在中世纪暖期气候相对较干,而小冰期则相对湿润,揭示出仙山泥炭沉积记录的气候信息具有区域一致性,为认识季风在短时间尺度的变化特征提供了依据。
Based on the analysis of n-alkanes in Peat Drilling Hole in Fujian Province, the climatic characteristics of the study area in the past 1,000 years have been discussed. The analysis shows that the distribution range of n-paraffins is mainly C_ (16) ~ C_ (35), odd odd carbon chain is dominant, and the odd and even advantages are obvious. The n-alkanes are closely related to the organic matter content (TOC). In typical peat layers, the TOC content is high, and the C_ (27), C_ (29) and C_ (31) In herbaceous or woody plants, the basin is in a relatively dry sedimentary environment; in the non-peat layer, the TOC content is low and the boreholes contain coarse sand or silt. The C_ (21) or C_ (23) The n-alkanes predominate, revealing that the organic matter is mainly from aquatic plants or bryophytes, indicating a relatively wet depositional environment. The ratio of C_ (23) / C_ (27) n-alkanes in the borehole is in the same direction as C_ (23) / C_ (29) and P_ Alternative indicators. According to the chronostratigraphic sequence, we use n-alkanes to reconstruct the history of vegetation evolution and climate change in the region since 1400. The results show that there are 3 times relative humidities and 4 relatively dry periods in the climate of the area of Fujian Province. In the borehole 358 ~ 280cm (about 600 ~ 910 AD), the climate is relatively dry, in 280 ~ 40cm (about AD 910 ~ 1640), more precipitation, humid climate, but there are two intermediate drying stage; In 40 ~ 0cm (about AD 1640 so far), precipitation is relatively small, the climate turns dry. Comparison of TOC content, C_ (23) / C_ (27) sequence of n-paraffins with the frequency series of droughts and floods in the south, stalagmite and diatoms shows that the climate in the study area was relatively dry during the Middle Ages and relatively humid during the Little Ice Age The climate information recorded in the sediments of Xian Shan has regional consistency and provides the basis for understanding the changing characteristics of monsoon on a short time scale.