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冰岛北部陆架MD992271孔沉积硅藻中喜暖硅藻数量持续减少以及喜冷藻类数量不断增加,反映了该区近3000年来气候变冷的趋势,而硅藻组合中这两类硅藻数量呈周期性的此消彼长,指示在趋冷的背景下,气候的冷暖交替过程.转换函数计算结果表明,该孔夏季表层海水温度变化大致可分3个阶段,在1400cal.aBP以前,温度基本高于平均值;在1400~700cal.aBP之间,温度在平均值上下起伏,而在700cal.aBP后,温度均处于平均值之下.在这3000多年间,还存在着4次明显的降温事件,降温事件的中心分别位于约2600,1900,1300和600cal.aBP.上述夏季表层海水温度变化和冰岛北部陆架HM107-03和MD992275孔资料相对比,明显具有一致性,同时也可与GISP2冰芯氧同位素及北大西洋深海沉积记录对比,说明冰岛北部陆架晚全新世夏季表层海水温度变化,受区域性气候变化的控制.直接导致上述海水温度变化,是影响该区暖流和寒流作用此消彼长的结果,而冰岛周边海域3000年来海流分布的基本格局未有明显改变.
The continuous decrease of diatoms and the increase of the number of hi-cold algae in pore-deposited diatoms in northern Iceland shelf MD992271 reflect the tendency of this region to cool down in the past 3000 years. However, the diatoms in these diatom assemblages are periodic The shift of sexuality indicates the alternation of warm and cold climate in the cooling background.The results of transfer function show that the temperature of surface seawater in summer can be roughly divided into three stages and the temperature is basically high before 1400cal.aBP At 1400-700 cal.aBP, the temperature fluctuated around the mean value, and after 700 cal.aBP, the temperature was below the average value. In the past 3,000 years, there were also four significant cooling events And the centers of the cooling events are located at about 2600, 1900, 1300 and 600 cal. ABP, respectively. The above-mentioned summer surface sea temperature changes are obviously consistent with the data of the boreholes HM107-03 and MD992275 in the northern shelf of Iceland and are also consistent with GISP2 ice core Oxygen isotopes and deep-sea sedimentary records of the North Atlantic, indicating that changes in the temperature of the surface seawater in the late Holocene during the Holocene in the northern shelf of Iceland are controlled by regional climate changes, which directly affect the above seawater temperature changes, However, the basic pattern of ocean current distribution in the waters around Iceland has not changed significantly in the past 3,000 years.